The proliferation of cellular antennas and other radiofrequency radiation (RFR) generating devices of the last decades has led to more and more concerns about the potential health effects from RFR exposure. Since the 2011 classification as a possible carcinogen by the International Agency for Research on Cancer (IARC), more experimental studies have been published that support a causal association between RFR exposure and health hazards. As regard cancer risk, two long-term experimental studies have been recently published by the US National Toxicology Program (NTP) and the Italian Ramazzini Institute (RI). Despite important experimental differences, both studies found statistically significant increases in the development of the same type of very rare glial malignant tumors. In addition to carcinogenicity, reproductive organs might be particularly exposed, as well as sensitive to RFR. In this work, we reviewed the currently available evidence from in vivo studies on carcinogenicity and reproductive toxicity studies in order to summarize the contribution of experimental research to the prevention of the adverse effects of RFR on human health. Since mobile phone usage has become an integral part of everyday life for the vast majority of the population, unprecedented human exposure to radiofrequency radiation (RFR) from conception until death has been occurring in the last two decades. Consequently, there is an increasing public interest in the possible health risks derived from mobile phone use and base station-related exposure.RFR, which includes radio waves and microwaves, correspond to 30 kHz–300 GHz the electromagnetic spectrum. RFR has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to ionize (to detach electrons from atoms or molecules), which is, therefore, known as non-ionizing radiation. The important properties of non-ionizing radiation include the frequency at which it is generated, measured in megahertz (MHz) or gigahertz (GHz), and the intensity of the waves, or the specific absorption rate (SAR), which is the rate of energy absorption per unit mass of biological tissue . RFR canAmong the effects induced by RFR, tissue heating is a well-established and biologically plausible mechanism: When the RFR exposure occur at levels high enough, the absorption of energy by a biological system could overcome its capability to regulate the body temperature. Assuming the phones are not emitting more than permitted, typical human exposures to RFR occur at intensities that are not capable of inducing significant tissue heating if devices are used according to the manufacturers’ recommendations for use.Those biological changes occurring when body temperature increase is below 1 °C are referred to as nonthermal RFR effects. Temperature variations within the range of 1 °C are considered as thermal noise . There iIn 2011 the International Agency for Research on Cancer (IARC), part of the WHO, declared RFR to be “possibly carcinogenic to humans”, group 2B , basing One of the biggest concerns is that RFR might have reproductive and developmental adverse effects, in particular, disturbing testicular function and altering sperm parameters. It is indeed probable that the penetration of RFR into the testis may be more pronounced than other tissues, given the lower protection of this organ by tissue, in comparison to others. It is well known that the temperature of the testicles is 2 °C to 3 °C lower than the rectal one, and the right temperature for spermatogenesis is considered to be 35 °C . The habThis review aims to address the current knowledge of both the carcinogenic and the reproductive/developmental hazards of RFR emerged from in vivo experimental studies. Firstly, cancer bioassays have been reviewed. Based on the animal model, reviewed articles were separated by paragraphs in studies on rats, mice and other models (including trans-genic models). Those experimental studies in which wild type or transgenic/tumor-prone strains of rats and mice were subjected to RFR long-term exposure of at least one year were taken into consideration. Those experiments with an exposure duration beneath the 12 months were deliberately excluded, since they can not be considered reliable carcinogenicity studies . Secondly, apical endpoints investigated in reproductive and developmental toxicity peer-reviewed studies were used for PubMed selection of relevant in vivo animal studies. Hence, those experiments in which the authors evaluated the effect of RFR exposure towards reproductive system health were reviewed. Based on the animal model, reviewed articles were separated by paragraphs in studies on rats, mice and other mammalian models.Since billions of people are exposed to the potential carcinogenic risks of RFR, studies in laboratory animals must be as sensitive as possible for really being informative. The Organization for Economic Co-operation and Development (OECD) and the NTP have drawn up specific guidelines for the conduction of carcinogenicity studies ,12. AmonAmong rat studies, La Regina et al. (2003), using a carousel system, tube-exposed Fischer 344 (F344) rats for 4 h/day, 5 days/week, for 24 months. Two different types of RFR  at one brain SAR level of 1.3 ± 0.5 W/kg each were applied to the animals. Each group (2 RFR and 1 sham) consisted of 160 rats (80/80). No significant differences between treated and sham-exposed animals were found in the incidence of any spontaneous tumors .Anderson et al. in 2004 exposed F344 rats to 1.6 GHz RFR. Animals were divided into three groups of treatment: One group was sham exposed, and two groups were subjected to a far-field RFR Iridium signal. Exposures started prenatally at levels resulting in fetal brain SAR of 0.16 W/kg. After parturition, 90 restrained animals per sex and per group underwent 2 h/day, head-first, near-field exposures for 5 days/week until the rats were two years old, with calculated levels of brain SAR corresponding to 0.16 W/kg and 1.6 W/kg and near-field sham controls. It was not observed any statistically significant difference among the three experimental groups as for the incidence of neoplastic lesions . In 2007, Smith et al. divided 1170 Han Wistar rats among 65 male and 65 female per group, exposing the animals for 2 h/day, 5 days/week for up to 24 months at three nominal SARs of 0.44, 1.33, and 4.0 W/kg to Global System for Mobile Communications (GSM) or Digital Cellular System (DCS) wireless communication signals. No adverse reaction was observed following exposure to different levels of both the signals. Particularly, except for those results that the authors reputed as isolated, trivial observations not related to the treatment, this study did not report any statistically significant finding in the incidence, multiplicity, latency, or type of any primary cancers that can be attributable to RFR neither in male nor in female rats . Also, five two-years promotional cancer studies involved promotion of N-Ethylnitrosourea (ENU)-induced cancer, four in F344 rats and one in SD rats ,18,19,20n = 200) of sham-exposed rats. Among those neoplasms found in the exposed rats were thyroid cancer and malignant lymphoma. The importance of these results is given by the fact that the thyroid gland is one of the most RFR-exposed organs during mobile phone usage, especially during a call [Among the studies conducted in Sprague-Dawley (SD) rats, in 1992 Chou et al. exposed 200 SD rats for 25 months, 21.5 h per day, to pulse modulated 2450-MHz RFR at 0.144–0.4 W/kg of whole body SARs. Exposed animals showed a statistically significant increase in the incidence of primary malignant tumors, compared to the same number  was the largest rodent bioassay carried out by this U.S. government Institution. SD rats were exposed to RFR in special chambers for up to two years, with exposure began in the womb. The RFR exposure was intermittent, 10 min on and 10 min off, for a total of about 9 h a day, with exposure levels of 1.5, 3, and 6 W/Kg/bw. Rats were exposed at a frequency of 1900 MHz to total body RFR from two technologies, CDMA and GSM . The Ramazzini Institute (RI) study was the largest long-term bioassay ever performed exploring the health effects of RFR, comprising 2448 rats. The whole-body exposure for 19 h/day of male and female SD rats to a 1.8 GHz GSM far field of 0, 5, 25, 50 V/m, started prenatally and lasted until natural death .NTP doses were established to mimic the localized exposure on body tissues from a cell phone placed near the body—and were, therefore, particularly higher than those used by the RI, which were, instead, similar to those found in our living and working environment to mimic the full-body human exposure generated by mobile telephony base antennas. Despite these differences, recently, both the studies found statistically significant increases in the development of the same type of very rare glial malignant tumors ,23.During the use of cordless and handheld mobile phones, the brain is the main target of RFR. An increase in gliomas of the brain, the same tumor found in people after long-term cell phone use, was observed in both NTP and RI studies, although a statistically significant increase was observed only by NTP. The results published by the RI highlighted a statistically significant increased incidence of a very rare glial tumor of the heart, the Schwannoma, in male rats treated at the highest dose (50 V/m). This is the same type of tumors found to be increased by NTP using far higher exposure levels, tumor involving the same hystotype of the acustic nerve (vestibular) neurinoma observed in humans after intensive mobile phone use in epidemiological studies . Both inIn the NTP study, an increased number of male rats bearing adrenal gland tumors was also considered to be related to exposure. The RI publication only documents brain and heart findings. Data from the other organs are about to be published.The studies discussed in this section are summarized in In addition to the study conducted in SD rats, NTP also conducted a carcinogenesis study in B6C3F1/N mice. Animals were located in special chambers and treated with RFR for up to two years, with exposure began at 5–6 weeks of age. The RFR exposure was intermittent, 10 min on and 10 min off, for a total of about 9 h a day, with exposure levels of 2.5, 5 m and 10 W/Kg. The whole body of the mice were exposed to RFR at a frequency of 1900 MHz, from two technologies, CDMA and GSM. In male or female mice, exposure to cell phone RFR did not significantly increase the incidence of any neoplastic lesions .Using B6C3F1 mice, Tillmann et al. (2007) experimentally evaluated the possible carcinogenic effects of RFR at 902 and 1747 MHz, respectively of the GSM and of the DCS standards. Mice were restrained and exposed over a period of 2 years for 2 h/day, 5 days/week to three different whole-body averaged SAR levels of 0.4, 1.3, 4.0 W/Kg body weight, or were sham exposed. No statistically significant increase in the incidence of any particular tumor type was observed in the RF exposed groups as compared to the sham exposed group . 2. The low-dose group (4.8 W/m2) was subjected to additional prenatal ethylnitrosourea (ENU) treatment of 40 mg/kg body weight, and showed an increase in the rate of lung tumor and in the incidence of lung carcinomas in comparison with the control group treated only with ENU [RFR cocarcinogenic effect was explored in the 2010 tumor promotion study by the same authors. Mice were exposed for two years to Universal Mobile Telecommunications System (UMTS) fields at intensities of 0 (sham), 4.8, and 48 W/mwith ENU .Similar results were obtained from a follow-up study in which mice were treated with RFR at SAR levels of 0 (sham), 0.04, 0.4, and 2 W/kg . The incThe studies discussed in this section are summarized in Among the studies conducted on transgenic/tumor-prone animal strains, in 1997, Repacholi et al. observed an increase in β-cell lymphoma in transgenic mice exposed to pulsed digital RFR. Such increase was observed for female pim1 (carrying a lymphomagenic oncogene) mice after 18 months of exposure to a modulated 900 MHz GSM signal of two 30-min periods per day, at SAR exposure levels ranging from 0.008 to 4.2 W/kg, averaging 0.13–1.4 W/kg . This ren = 120 per group) in a “ferris-wheel” system. Tube-restrained animals were RFR-radiated for 1 h/day and 5 days/week within two years at 0, 0.25, 1.0, 2.0, and 4.0 W/kg as whole body SAR levels. In addition, the study included a non-restrained cage control group, and a positive control, treated only with 50 mg/kg ENU. All in all, contrary to what observed by Repacholi, no lymphoma increase was observed in the RFR exposed groups [In particular, in 2002 Utteridge and collaborators used a modulated 898.4 MHz GSM signal for exposing female heterozygous pim1 transgenic (lymphoma-prone) mice (d groups .n = 50/group/sex) were tube-restrained and treated for 1 h/day, 7 days/week, up to 18 months, at whole body SAR levels of 0, 0.5, 1.4, 4.0 W/kg. The results of this bioassay do not suggest any effect due to pulsed 900 MHz RFR exposure on the onset of tumors, thus, disproving once again, the results by Repacholi et al., under the conditions used [In the study by Oberto et al. (2007) that the authors defined as “an extension of a previously published study conducted by Repacholi et al.”, female Pim1 transgenic mice  or concurrently to the treatment with benzopyrene (over five months). RFR at the frequency of 2450 MHz showed to induce cancer promotion at both 50 and 150 W/ms tumors .The studies discussed in this section are summarized in Both OECD and NTP recently updated their study guidelines for reproductive and developmental toxicity adding various functional endpoints for assessing how an agent can affect the reproductive and endocrine status of animals ,33. HereOne of the first studies investigating cellphone RFR was conducted in SD rats and examined just the effects, due to exposure on testicular and sperm function. Rats were restrained in cages built ad hoc in Plexiglas, and mobile phones were placed 0.5 cm under the cages. Cellular phones with frequencies between 890 and 915 MHz were activated at a SAR level of 0.52 W/kg for 20 min/day for up to one month. No statistically significant difference between treated and control animals was reported in this study for any of the analyzed parameters . Testicular histological changes in rats exposed to 848.5 MHz RFR for 12 weeks were explored by Lee et al. (2010). Male SD rats underwent two daily exposure periods of 45-min, with an interval period of 15 min. The authors investigated the concentrations of MDA in the testis and epididymis, the sperm count in the cauda epididymis, the frequency of the stages of spermatogenesis, the germ cell count, and the appearance of apoptotic cells in the testis. According to the results of this study, rat spermatogenesis was not influenced by any detectable adverse effect .Two years later, the same researchers examined the effects of combined exposure to 848.5 MHz CDMA and 1950 MHz WCDMA RFR on most of the same parameters analyzed in their previous study. SD rats underwent RFR exposure for 45 min a day, 5 days a week for a total of 3 months, at an average whole-body SAR of 4.0 W/kg for both the frequencies. Based on the findings, they concluded that not even such simultaneous exposure resulted in any observable adverse effect on rat testicular function .In 2011, Imai et al. performed a study on adolescent SD rats, exposing the animals to 1.95 GHz RFR at a whole-body SAR level of 0.4 W/kg for 5 h/day, 7 days/week, for a total of 5 weeks. The exposure period corresponded with the reproductive maturation of the rats. No difference in weights of the epididymis, seminal vesicles, testis or prostate was observed between exposed and control rats. Sperm count in the epididymis and testis was not influenced by the treatment, and no alterations in the sperm motility, morphology, or in the histological appearance of seminiferous tubules, including the spermatogenic cycle stage, was observed between treated and untreated animals .Among “non-influential” studies conducted in Wistar rats, in 2007 Ribeiro et al. investigated the effects of subchronic RFR exposure emitted by GSM cellular phone (1.835–1.850 GHz) for 1 h/day for 11 weeks on the testicular function. Epididymal sperm count, epididymal and testicular weight, total testosterone in the serum and lipid peroxidation levels in these organs, such as various qualitative testicular histopathological end points were analyzed. No statistically significant difference was found between treated and control animals for all the considered endpoints .A study by Trošić et al. was aimed to establish the possible negative impact of RFR exposure on Wistar rat male reproductive health. The research group evaluated the count, motility and form of spermatozoa from the cauda epididymis, as well as the histology of the testis. Animals were total body irradiated for 1 h/day over two weeks to 915 MHz RFR, at the average SAR value of 0.6 W/kg. An haemocytometer was used for microscopically determining the quality, quantity and structure of free sperm cells taken from the epididymis. This study revealed no statistically significant changes in any of the evaluated endpoints .In 2007, the study by Yan et al. reported a statistically significant decreased motility of the epididymal sperm of SD rats treated with 1.9 GHz RFR, in comparison to controls. Furthermore, treated rats, unlike the unexposed, showed abnormal clumping of spermatozoa. Compared to the previous study by Dasdag et al., the apparent opposition in the results obtained by Yan et al. may be likely due to the longer treatment period to which rats from the same strain were subjected in this experiment. In fact, the experimental rats, restrained in special plastic holding tubes, were daily exposed to cell phone RFR for three hours, followed by 30 min of non-exposure outside the tubes, and, to follow, by another exposure period of 3 h more .In 2014, Qin et al. used adult male SD rats to explore the circadian effects of the exposure to RFR on reproductive functional markers. Animals in circadian rhythm (based on melatonin measurements) underwent RFR exposure at 1.8 GHz, at a SAR level of 0.0405 W/kg, for 2 hours a day, for 32 days in total. Circadian rhythms were found disrupted in animals exposed to RFR, as well as testosterone levels, daily sperm production and sperm motility were found decreased, the activity of γ-GT and ACP down-regulated, and the mRNA expression of cytochrome P450 and steroidogenic acute regulatory protein were altered in comparison to sham exposed rats. These results show that RFR exposure can negatively impact male reproductive functional markers, both in terms of total daily levels and in terms of circadian rhythmicity .Finally, in 2019, Guo et al. explored the effects of 30 days exposure to pulsed modulated RFR at 220 MHz on the sperm quality in male adult SD rats. Calculated average whole body and testis SAR values were 0.030 W/kg and 0.014 W/kg, respectively. Compared to controls, the sperm quality in the treated group decreased significantly. Sperm cells quality was assessed by measuring the survival rate, the number and the abnormalities of spermatozoa. After the treatment, the level of Leydig cells secreting factor assessed by ELISA decreased significantly, whereas the Western blotting-assessed levels of caspase 3, cleaved caspase 3, and the BAX/BCL2 ratio in the testis markedly increased. Moreover, the levels of secreted factors of Sertoli cells assessed by ELISA and the testis morphology by HE staining, showed an evident change following RFR treatment . Different outcomes emerged from most of the studies conducted in Wistar rats, for example when rats of the same strain were exposed to RFR emitted by an active cell phone at the GSM frequencies of 0.9 and 1.8 GHz for 1 h a day for 1 month, in comparison to a group of animals exposed for the same period to a no battery cell phone. Total sperm count was not affected, but sperm motility of experimental rats was significantly reduced by the exposure. The average percent of motile sperm reduced of about 40%, being 72.0% ± 8.7% in control rats and 43.1% ± 10.0% in RFR-exposed rats. Moreover, epididymis and testis of RFR exposed animals showed a marked increase in lipid peroxidation and a significant decrease in GSH content [Kesari et al. (2010) exposed adult rats for 2 h/day up to 5 weeks to 900 MHz RFR with a level of SAR estimated to be 0.9 W/kg. Treated animals showed a significantly decreased total sperm count and level of protein kinase C (PKC), as well as an increase in apoptosis of spermatozoa. The enzyme PKC is commonly located in head, neck, and tail of human sperm, and plays an important role in the acrosomal reaction and sperm motility. The authors associated the reduction in PKC activity to the RFR-dependent possible overproduction of ROS in the sperm of exposed animals .To investigate the hypothesis of an increased production of free radicals and other effects on fertility, the same researchers exposed the same strain of male rats to the same type and duration of RFR exposure. They found the antioxidant enzymes glutathione peroxidase and superoxide dismutase significantly lowered, and the catalase and malondialdehyde significantly increased in the exposed group, compared to the unexposed. Moreover, testicular sperm of exposed rats showed an increased content in micronuclei and a significantly changed cell cycle of G(0)–G(1) and G(2)/M. Generation of free radicals (ROS) was significantly increased in sperm .In the same year, Meo and collaborators exposed male Wistar albino rats to GSM cell phone RFR for half an hour a day or for 1 h a day, for a 3 months period in total. In comparison to control rats, 18.75% of longer exposed rats showed the arrest of sperm maturation and hypospermatogenesis. The exposure to cell phone RFR for half an hour a day did not result in any abnormal findings in the animals . In a study of 2012, Kesari and Behari exposed Wistar rats to cell phone RFR for 2 h a day for 45 days. Exposed rats showed a significant decrease in testosterone levels and an increased activity of caspase-3 protein, compared to controls. Transmission Electron Microscope observations also revealed sperm head and midpiece of sperm mitochondrial sheath distortions. Furthermore, this study revealed a reduction in litter size and weight of the progeny deriving from RFR-exposed male rats mated with unexposed females, compared to controls. The authors attributed these observations to ROS overproduction in rats exposed to cell phone RFR .A long-term study analyzed the effects of exposure to cell phone emitting at 900 MHz on the reproductive organs of male rats. Specific levels of SAR for testis and prostate ranged from 0.0373 to 0.0623 W/kg. Exposed rats underwent RFR 3 h daily for one year. Once the experiment ended, the authors claimed that, under the condition used, RFR alter some reproductive parameters. In particular, the morphologically abnormal spermatozoa rates of treated rats were found significantly higher, in comparison to control rats. Moreover, at the histological examination of the seminiferous tubules, the Johnsen testicular biopsy score and the tunica albuginea thickness were found significantly decreased in the exposed animals .In the same year, a study by Meena et al. aimed to evaluate the protective effect of the well-known antioxidant melatonin (MEL) in male Wistar rats, demonstrated that the prolonged RFR exposure could generate oxidative stress-mediated damage of the testes. The animals were divided into four groups: Controls (sham exposure); 2 mg/kg MEL treated; 2.45 GHz RFR exposed; and co-treated with RFR + MEL. Exposure was of 2 h a day for 45 days, and SAR was estimated at 0.14 W/Kg. Experimental observations showed that RFR biochemically induced oxidative damage by significantly decreasing testicular LDH levels and by increasing testicular MDA and ROS levels. Furthermore, RFR significantly affected the sperm count, the levels of testosterone, the fragmentation of DNA in testicular cells, the content of xanthine oxidase and carbonylated proteins .Exposure effects on testes were also evaluated in another long-term study, in which rats underwent Wi-Fi-emitted 2.4 GHz RFR for 24 h a day during 12 months. Among the different parameters analyzed, the weight of the seminal vesicles and epididymis, the diameter of the seminiferous tubules and the thickness of tunica albuginea were found significantly lowered, compared to controls, while head defects and mitochondrial distribution alterations in the mid-piece of sperms significantly increased in the exposure group .Adult male Wistar-Albino rats were long-term treated with 2.4 GHz RFR reproducing Wi-Fi exposure to evaluate the potential DNA damage on a series of different tissues. The detection of possible DNA damage was realized through the method of the single cell gel electrophoresis assay (comet). In exposed rats, the % tail DNA values of the liver, brain, kidney, and skin tissues were higher than that of the controls, but the increase resulted statistically significant only in testes tissue .In a study conducted in 2018, Narayanan et al. investigated the possible adverse effects on blood biochemical and reproductive parameters of adolescent male albino Wistar rats exposed to 1h/day 900 MHz RFR from a mobile phone for 28 days. The treatment caused a slight reduction in sperm motility and a statistically significant increase in abnormal sperm percentage, in comparison to unexposed rats. Moreover, the testes of 900 MHz-exposed animals showed a loss of germ cells, in particular, spermatids and spermatocytes. Furthermore, the activity of testes caspase-3 was slightly increased, and MDA concentration was found increased in exposed rats .The most recent study performed in Wistar rats for evaluating the effects of RFR on the male reproductive system was that of Gautam et al. in 2019. Rats underwent cell phone RFR exposure from 3G technology for 2 h/day for 45 days in specially designed exposure structures. A spermatogenic cells decrease was detected through histopathological examination, as well as sperm membrane and sperm tail morphology alterations. Among the various biochemical and physiological parameters analyzed, significant increases in lipid peroxidation and ROS levels with concomitant sperm count decrease and alteration in the mitochondrial activity of spermatozoa were observed .The studies discussed in this section are summarized in In the first study reported on mice, the animals were subjected to 0.09 W/kg RFR exposure, at 900 MHz. Polycarbonate cages were accommodated within an ad hoc built waveguide where mice were irradiated for 12 h/day for a week. The mitochondrial genome and the nuclear β-globin locus resulted significantly damaged when the DNA integrity was detailed analyzed through qPCR. Apart from this genotoxic effect in epididymal spermatozoa, this study did not document any other detrimental effect by RFR exposure on the development of male germ cell . NonetheA 2010 study by Otitoloju et al. exposed male mice at residential quarters and a workplace complex to RFR from radio base antenna at 900 to 1800 MHz for six months, and compared to unexposed animals observed a statistically significant increase  in the occurrence of sperm head defects. Such abnormalities were found to be dose-dependent, and mainly consisted of pin-head, banana-shaped and knobbed hook sperm head .The study conducted by Pandey et al. in 2017 using Swiss albino mice investigated the effects of RFR exposure on male germ cell transformation kinetics, and evaluated the possible recovery. Animals were exposed to 900 MHz RFR for 4 or 8 h a day for a total of 35 days. Some animals were sacrificed after those 35 days of exposure, while others were given the opportunity to recover from exposure for further 35 days. The damage index of germ cells and the sperm head abnormalities were significantly increased in exposed mice. Flow cytometric estimation of germ cell subtypes in mice testis revealed 2.5-fold increases in spermatogonial populations with significant decreases in spermatids. A reduction of almost three times in primary spermatocyte to spermatid turnover, and a fourfold reduction in spermatogonia to spermatid turnover were found, to indicate a spermatogenesis arrest in the premeiotic stage. As a consequence, post-meiotic germ cells markedly decreased at the histological observation of the testes, as well as the sperm count lowered in mice exposed to RFR. Furthermore, histological alterations, such as epithelium depletion, maturation arrest and loss of immature germ cells into the seminiferous tubule lumen were also observed. Nevertheless, all the observed effects showed varying degrees of recovery when animals underwent to a post-treatment recovery period . In a very recent experimental study, the same authors investigated the impact of GSM RFR at 900 MHz on germ cells development during spermatogenesis of Swiss albino mice. Animals were divided into four groups, one of which underwent RFR exposure 3 h a day twice, for 35 days, another received the same exposure with 5 mg/kg bw/day MEL supplementation, a third group received only MEL, and the last one remained unexposed. As consistent with the previous experiment, RFR exposure caused extensive DNA damage in germ cells, arrest in pre-meiotic stages of spermatogenesis, eventually leading to sperm head defects and low sperm count. Moreover, excess free radical generation was revealed through biochemical assays, thus, leading to histological and morphological changes, respectively in testis and germ cells morphology. These effects were either diminished or absent in RFR-exposed animals supplemented with MEL . This reThe studies discussed in this section are summarized in Two studies were performed by the same research group using adult male rabbits to evaluate the effect of mobile phone-emitted RFR on weekly collected semen samples. The two lagomorph studies were conducted with the identical experimental design and protocol of exposure and differed only in the frequencies used, which were of 900 MHz  and 800 Lary et al. exposed pregnant SD rats to 100 MHz RFR at a SAR level of 0.4 W/kg, for 6 h and 40 min/day. The exposure period was from gestation day 6 to 11, for a total of 40 h. The SAR value used corresponded to the maximum permissible level as indicated by the 1982 American National Standards Institute (ANSI) standard for RFR exposure. Irradiated rats did not differ in the percentage number of malformed fetuses, implantations per litter, percentage of implantations dead or resorbed, fetal weight, fetal crown-rump length, or fetal sex ratio, compared to untreated (sham-exposed) rats. The results showed a lack of embryotoxic or teratogenic effect in rats at the maximum permissible RFR exposure level following the 1982 ANSI recommendations .A 2009 study by Ogawa et al. investigated the effect of 90 min/day 1.95 GHz CDMA emission on SD rats embryogenesis, exposing the dams from gestation day 7 to 17. All the animals were killed at gestational day 20, and the fetuses were extracted by cesarean section. The authors compared treated and untreated rats for placental weights, number of live, dead or resorbed embryos, sex ratios, weights, or visceral, external, or skeletal abnormalities of live fetuses Neither differences in maternal body weight gain, nor adverse effects of RFR exposure on any considered embryotoxic and reproductive parameters analyzed were observed .In a study of 2010, Takahashi et al. evaluated the effects of 2.14 GHz RFR reproducing the emission of radio base antennas of mobile telephony. Pregnant SD rats were long-term whole-body exposed at two different exposure levels and compared to untreated animals. The calculated average SAR at the high exposure level ranged from 0.066 to 0.093 W/kg for the dams, and from 0.068 to 0.146 W/kg for the fetuses and the F(1) progeny. At the low exposure level, the SARs were estimated to be around 43% of those calculated for the high level. Treated rats underwent 20 h/day RFR exposure during gestation and lactation period. Parameters evaluated in dams were gestational conditions, organ weights and growth, while the F(1) generation was evaluated at 10 weeks of age for growth, development, survival rates, hormonal status, physical and functional development, memory function and reproductive ability. The F(2) offspring were analyzed for possible effects of teratogenicity and embryotoxicity. Both the RFR exposed dams and F(1) progeny showed no treatment-related effect for any of the parameters evaluated. The same was observed for the F(2) generation. The RFR exposure conditions used in this study did not determine any adverse effect on rat pregnancy or development .Among the “non-influential” studies conducted in Wistar rats, two were conducted by Poulletier de Gannes and collaborators. Animals were exposed over two generations to a 2450 MHz Wi-Fi emission signal during gestation and lactation periods. In 2012, these researchers evaluated the possible adverse effects on pregnant rats and their F(1) generation of a Wi-Fi signal prenatal exposure of 2 h a day, 6 days a week, for a total of 18 days. The whole-body SARs used corresponded to 0.08, 0.4, and 4 W/kg. No statistically significant effects were noted at each dose tested in both dams and their pups, respectively in terms of observed abnormalities and pre- and postnatal development signs of toxicity .The following year, another similar study from the same authors was conducted in rats of the same strain for investigating the exposure effects to a Wi-Fi signal with the same frequency on the male and female reproductive system. Adolescent animals were exposed for 1 h a day and 6 days a week to RFR, for three weeks in the case of males and for two weeks in the case of females. Afterwards, the rats were mated, and the couples treated for three more weeks. The day before parturition, clinical signs, abnormalities and mortality were evaluated in the fetuses. Under the condition used, the exposure to the Wi-Fi RFR signal did not determine any detrimental effect on fertility and reproductive organs either in male or in female rats. Likewise, the fetuses did not show any macroscopic abnormality .Aït-Aïssa assessed immunological biomarkers in the sera of young Wistar rats RFR-exposed in utero and postnatally. Pregnant rats were located in a reverberation chamber and exposed to a Wi-Fi signal at the frequency of 2.45 GHz for 2 h a day and 5 days a week. Dams were whole-body exposed at average SAR values of 0, 0.08, 0.4, and 4 W/kg from gestation day 6 to 21. Furthermore, three newborns per litter were exposed for an additional 35 days. Antibodies directed against 15 different antigens related to damage and/or pathological markers were analyzed using the biochemical assay ELISA performed on sera of the experimental rats. The humoral response of the newborns showed no changes among different groups, for all the SAR levels used and the biomarker types considered. Some data on gestational outcome following in utero exposure to Wi-Fi signals were also provided by the present study; in particular, mass evaluation of dams and pups and the number of pups per litter were monitored, as well as the genital tracts of young rats were analyzed for abnormalities by measuring anogenital distance. Under the conditions used, the author’s findings indicate the absence of adverse effects, due to Wi-Fi signal exposure on general conditions and delivery in of Wistar rats .One of the first evidence of teratogenicity, due to RFR in SD rats was that showed by Lary et al. in the early 1980s using low, non-thermal exposure level, with results in contrast with other findings from the same authors . For invA series of experimental studies conducted by Nelson and his research group investigated in depth the combinatory developmental toxicity effects of RFR at 10MHz and the organic compound 2-methoxyethanol (2ME). For this purpose, SD rats were exposed to the two agents individually or concurrently, in comparison to sham-exposed animals. The authors used highly diverse doses and timing of exposure of pregnant rats; after the sacrifice of the animals on gestation day 20, external malformations were evaluated in the examined progeny. Results showed that the adverse effects produced by both the treatments administered alone were enhanced when the agents were co-administered. In addition to a significant, dose-related, increased frequency of malformations, the combination treatment enhanced the severity of malformations too. This extended project demonstrated that the co-administration of RFR and 2ME synergistically induced teratogenic effects, but only at hyperthermic levels of RFR ,69,70,71The same research group administered with methanol SD rat dams concomitantly exposed to RFR, in order to evaluate whether the interactive effects observed for RFR and 2ME were limited to this agent, or if similar synergies could be observed with other chemicals. After the sacrifice of the animals on gestation day 20, external malformations were evaluated in the examined progeny. When RFR or methanol was administered alone, the authors observed a statistically significant increase in the number of resorbed fetuses. The same was not observed when the agents were co-administered to experimental rats . FurtherTo evaluate the impact of the prenatal exposure to 1800 MHz RFR on bone development, pregnant SD rats were exposed for 6, 12, and 24 h/daily for a total of 20 days. The rats were inspected at the end of the day 60 after birth, and compared to the progeny of untreated dams. The increase in prenatal RFR exposure time caused a significant decrease in the levels of cartilage at rest and a significantly increased number of apoptotic myocytes and chondrocytes. Importantly, Erkut et al. demonstrated that an exposure of 24 h per day to RFR impaired tibia, ulna and femur development. Furthermore, a calcineurin activity decrease was observed in both muscle and bone tissues. This study indicated that the development of muscle and bone tissues was negatively impaired by prenatal exposure to 1800 MHz RFR .The study by Oral et al., in 2006, investigated the potential adverse effects of RFR on the endometrial tissue of Wistar rat, with particular reference to RFR-induced oxidative stress and apoptosis. Animals were exposed to 900 MHz cell phone RFR for 30 min a day, for one month in total. In their study, the authors evaluated lipid peroxidation trough MDA as a marker of endometrial impairment induced by oxidative stress, and Bax, Bcl-2, caspase-3, and caspase-8 to assess apoptosis immunohistochemically. Based on the findings from this study, the electromagnetic fields emitted from cell phones may cause oxidative stress and endometrial apoptosis .The studies discussed in this section are summarized in Two studies regarding the potential RFR impact on mating were conducted in mice. In 2009, a large study performed in both female and male C57BL mice living over four generations under constant  exposure to three doses of UMTS RFR at 1966 MHz investigated histological, physiological, behavioral and also reproductive parameters. Adult mice underwent whole-body RFR exposure at the average SARs of 0.08, 0.4, and 1.3 W/kg , and were compared to control (sham-exposed) animals. This study did not report any RFR-induced significant effect on both male and female reproductive system, particularly for what concerns the offspring development, the appearance of reproductive organs, and the fertility potential .In the study by Zhu et al. (2015), mice were treated for 15 days with continuous 900 MHz RFR for 4 h/day at average SAR of 0.731 W/kg. Ended the treatment, all the exposed mice were individually mated with three mature virgin females. After 7 days, each male mouse was moved to a new cage for mating with three other female mice. This process was repeated for four consecutive weeks in total. At gestation day 18, all female mice were sacrificed for examining uterine content and evaluating the putative mating. All the observations conducted during the one month-long mating period showed no statistically significant differences in untreated female mice mated with treated male mice as regards total and live/dead uterine implants and percentage of pregnancies, in comparison to females mated with control male mice. As consistent with the previous study, this study showed no RFR mutagenic potential on male germ line .In three different works, Finnie and collaborators explored the impact of cell phone RFR exposure on fetal mouse brain development, investigating different outcomes. The common design contemplated the use of a specifically built 900 MHz exposure system, through which pregnant mice received for 1 h/day a far-field, whole body exposure at a SAR level of 4 W/kg from gestation day 1 to 19. In the first experiment, the authors explored the effect of cell phone exposure on blood-brain barrier (BBB) permeability in the immature mouse brain. On the 19th day of gestation, just before delivery, heads were collected from fetuses. The integrity of BBB was evaluated by immunohistochemistry using endogenous albumin as a vascular tracer in the cerebral cortex, thalamus, hippocampus, midbrain, cerebellum, medulla and basal ganglia. No albumin extravasation was found in brains from control or exposed mice, indicating no increase in vascular permeability of the considered regions of the fetal brain .To study the expression of immediate early gene c-fos as a marker of neural stress, the authors collected fetal heads on gestational day 19 as in the previous experiment. No statistically significant change in the expression of c-fos was immunohistochemically observed in the same brain regions evaluated in the previous experiment. The lack of difference in c-fos immunoreactivity between control and exposed brains indicated no stress response in the brain of the fetuses following cell phone RFR exposure during gestation period .In their third study, the same authors collected from each animal three coronal sections of the brain, including various anatomical regions to investigate a possible stress response given by heat shock proteins (HSPs) induction. The immunostaining of HSP25, 32 and 70 revealed no stress response. Exposure of mouse fetal brains to cell phone RFR during the gestation period did not cause any stress response by immunohistochemically evaluating HSPs .Magras et al. in 1997 studied the possible adverse effects of RFR exposure on the prenatal development of mice. Mice were located in sites of different power densities around an “antenna park” and were mated five times in a row, until 118 pups were generated. Thus, newborns were weighed, measured, and macro- and microscopically examined. Authors observed a progressive decrease in the number of generated newborns per dam, leading to irreversible infertility . The evaluation of RFR-induced possible toxic effect on mouse ovaries was the aim of the 2009 study by Gul et al. using 21 days old mouse female pups. Pregnant mice underwent cell phone RFR by placing mobile devices under the cages for the entire pregnancy period. Cell phones in standby position were turned on to speech position for 15 min every 12 h. Female newborns were sacrificed on day 21 after delivery, and the right ovaries were collected for determining the number of follicles. Findings from this study indicated a significantly decreased number of follicles in exposed pups compared to controls, indicating a toxic intrauterine effect of RFR on pup ovaries .The studies discussed in this section are summarized in Some long-term studies published up to the 2011 RFR IARC evaluation failed to demonstrate the carcinogenicity of RFR in experimental animals. RFR exposure has not been considerably linked to an increased incidence of tumors at any site both in rats or mice exposed for 24 months at different RFR intensities ,14,15,25As reported in the present review, more in vivo bioassays on RFR have been conducted since the 2011 IARC review, most of which adopted improved exposure systems and more accurate measures of RFR dosimetry. In particular, the two long-term experimental studies by NTP and RI were performed for evaluating the effects of everyday human exposure to RFR electromagnetic fields. NTP doses have been established to mimic the localized exposure on body tissues from a cell phone placed near the body, and, are therefore, particularly higher than those used by the RI, that is instead similar to those found in our living and working environment to mimic the full-body human exposure generated by mobile telephony base antennas. Despite the differences, recently, both studies reported a statistically significant increased incidence of the same type of very rare glial malignant tumors of heart (schwannoma) and brain (glioma). These tumors involve the same cells of the acoustic nerve vestibular neurinoma observed in humans in certain epidemiological studies. Another fact supporting this consistency is that the Schwann cells are glial cells of the peripheral nervous system whose role is to form myelin, and are analogous to oligodendrocytes of the central nervous system. The NTP defined as clear evidence the carcinogenic activity of GSM-modulated 900 MHz RFR of mobile phones, particularly based on this statistically significant increase in the development of malignant heart Schwannoma in male SD rats . NonetheAs indicated by animal studies focusing on female reproductive system outcomes, the main targets of the potential adverse effect, due to RFR exposure are endometrial tissue, ovarian follicle numbers, granulosa cells, quality of oocytes and embryos during pregnancy. However, to date studies conducted in mammals regarding both female reproductive system and other reproductive/developmental endpoints are highly diverse, very inconsistently conducted and, most of all, report different specific outcomes, making it difficult to come to a conclusion about the different specific subjects. On the other side, the evidence from studies on male reproductive system suggest that RFR exposure might negatively affect male fertility. The increased sperm cell death rate accompanied by reduced sperm quality and motility seems to be the more recurring effects, due to RFR exposure in SD rats ,39,40. GSeminiferous tubules, spermatozoa and Leydig cells are the main targets of this damage, and sperm count, motility and morphology represent the more frequently affected parameters. The abnormalities highlighted in many studies are likely related in a direct manner to the duration of mobile phone use and/or to the proximity to the RFR source. Several studies support the hypothesis that RFR exposure causes an increase in oxidative stress, leading to DNA and sperm membrane lipid damage which eventually cause the aforementioned effects. Therefore, it is essential to conduct mechanistic studies for elucidating the manner in which RFR impairs biological function, thus, providing a solid rational cause. Moreover, more studies are needed to supply stronger evidence that RFR emitted from mobile telephony base antennas and the use of the cell phone alter sperm and gonads functions given the many limitations characterizing the existing literature. Nevertheless, based on the in vivo animal studies conducted so far, it is likely that RFR could negatively impact sperm damaging male human fertility, especially when the mobile phone is kept in active mode in an area close to testicles. In conclusion, according to NTP, there is now clear evidence that RFR causes cancer in experimental animals. RFR re-evaluation has also been listed as a priority by IARC . There i


I2 (I–squared) = 88.5), propionate , and butyrate  than nonobese controls. The subgroup analyses showed no evidence of heterogeneity among obese individuals with a BMI >30 kg/m2 (2I = 0.0%). At the phylum level, the abundance of fecal microbiota was reduced in obese compared to nonobese individuals, but the difference was not statistically significant . The currently available human case-control studies show that obesity is associated with high levels of SCFA but not gut microbiota richness at the phylum level. Additional well-designed studies with a considerable sample size are needed to clarify whether this association is causal, but it is also necessary to identify additional contributors to SCFA production, absorption, and excretion in humans.There have been mixed results regarding the relationship among short chain fatty acids (SCFAs), microbiota, and obesity in human studies. We selected studies that provided data on SCFA levels or fecal microbiota abundance in obese and nonobese individuals and then combined the published estimates using a random-effects meta-analysis. Obese individuals had significantly higher fecal concentrations of acetate (SMD (standardized mean differences) = 0.87, 95% CI (confidence interva) = 0.24–1.50,  Obesity is a state in which excess fat accumulates in the body due to an imbalance between energy intake and energy consumption . As the Short chain fatty acids (SCFAs) are organic fatty acids with one to six carbon atoms and are the major anions produced by microbial fermentation of undigested carbohydrates, but the amount of SCFAs depends on various host, environmental, dietary, and gut microbiota factors . ButyratEmerging evidence based on numerous animal studies has shown that the gut microbiota and its metabolites, particularly SCFAs, play an important role in obesity ,6,7. TheMeanwhile, several studies have shown that gut microbiota compositions associated with the production of SCFAs are also associated with obesity. However, this relationship has not yet been clarified in humans. For example, Furet JP et al. reported an increase in phylum Firmicutes and a decrease in Bacteroidetes associated with obesity ; howeverTherefore, the main objective of the current meta-analysis based on previous human studies was to investigate whether SCFA levels in obese individuals differ from those in nonobese individuals. The secondary objective of this study was to determine whether the fecal microbiota abundance in obese and nonobese individuals reported in the literature on the relationship between SCFAs and obesity is different.We planned, conducted, and reported this systematic review according to widely accepted quality standards for reporting meta-analyses of observational studies in epidemiology and preferred reporting items for systematic reviews and meta-analyses guidelines ,17. A medical librarian with experience in systematic reviews participated in designing the search strategy. We searched the PubMed, Cochrane Library, and EMBASE databases via Elsevier for reports published between March 1953 and May 2018, and an updated search was performed in May 2019. A PubMed search for studies on SCFAs and obesity was conducted without restrictions by combining search terms that were synonymous with or related to SCFAs and obesity. The keywords used in the PubMed search were converted into search tags for the Cochrane Library and EMBASE databases . FurtherPublished articles were included in this meta-analysis if they met the following criteria: (1) Case-control studies that were conducted in humans rather than animals; (2) studies that provided data on SCFA levels in individuals both with and without obesity; and (3) studies that were written in English and published in their entirety. The exclusion criteria in this meta-analysis were the following: (1) Articles that did not satisfy the inclusion criteria; (2) publication types, such as animal studies, reviews, case reports, and systematic reviews; and (3) studies that did not provide sufficient data on SCFA levels, including means, medians, standard deviations (SDs), and/or standard errors for individuals with and without obesity.Two investigators (Sang Yhun Ju and Kyu Nam Kim), the coauthors of the present study, independently extracted the data from the original reports. The following information was extracted: First author’s last name, year of publication, country, age, sex, sample size, SCFA levels, SCFA assessment methods, fecal microbiota abundance, and definitions of obesity used. Disagreements between the two reviewers were resolved by consensus. The methodological quality of the included studies was evaluated using the Newcastle–Ottawa scale (NOS) criteria for case-control studies, which contained nine items that were grouped into three major categories. The maximum scores were 4 for selection, 2 for comparability, and 3 for exposure. A final score of 7 or more was indicative of a high-quality study.The quality of evidence was evaluated by means of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria . Two inv2I statistics [2I values greater than 50% indicated high heterogeneity. Heterogeneity was also assessed by comparing the results from studies grouped according to mean age using meta-regression. To evaluate the potential sources of heterogeneity in the analyses, we also conducted subgroup and sensitivity analyses. Publication bias was evaluated visually using Begg’s funnel plot and Egger’s test [p-values for Egger’s test were less than 0.1. All statistical analyses were performed using Stata software, version 15.0 .The data of interest, presented as continuous values (means and SDs), were used to perform the meta-analysis to obtain the standardized mean differences (SMDs) and 95% confidence intervals (CIs) of the SCFA levels of participants with obesity and controls. The SMDs were calculated by subtracting the means of SCFAs levels between the two groups and dividing by the standard deviations. Thus, studies for which the difference in means is the same proportion of the standard deviation will have the same SMD, regardless of the actual scales used to make the SCFAs measurements. An SMD below 0.5 was considered small, 0.5–0.8 was considered moderate, and over 0.8 was considered large . Our proatistics . I2 valur’s test . In the κ = 0.19). After we further examined the 29 identified articles, 22 articles were excluded  and obese (BMI >30 kg/m2) [The characteristics of the seven included studies and the SCFA datasets are summarized in 0 kg/m2) . One art0 kg/m2) . In addi0 kg/m2) ,9,10,13.I2 = 94.3%), acetate (I2 = 88.5), propionate (I2 = 82.3%), and butyrate (I2 = 81.7%) concentrations but not in iso-butyrate (I2 = 18.5%), valerate (I2 = 0.0%), or iso-valerate (I2 = 0.0%) concentrations.According to the random-effect meta-analysis results shown in p = 0.580), acetate (p = 0.621), propionate (p = 0.580), butyrate (p = 0.587), iso-butyrate (p = 0.380), valerate (p = 0.495), and iso-valerate (p = 0.783).2 (2I = 94.8%), propionate , and butyrate  in obese individuals compared to the fecal concentrations in nonobese individuals. The levels of total SCFAs , valerate , iso-valerate , and iso-butyrate  did not differ between the fecal samples of obese individuals and nonobese individuals. In the 17 datasets of obese individuals with a BMI >30 kg/m2 (2I = 0.0%), acetate , propionate , and butyrate  in obese individuals compared to the fecal concentration in nonobese individuals. These subgroup analyses showed no evidence of heterogeneity among obese individuals with a BMI >30 kg/m2.We excluded four datasets with BMI-Z scores of 2.14 to 5 and one dataset with a SCFA blood sample from our subgroup analyses . In the 2 a, there 30 kg/m2 b, there In the sensitivity analyses, we recalculated the combined SMD of SCFAs by omitting each study individually . The stu2I = 72.1%) and Firmicutes (2I = 58.7%). p = 0.833; Firmicutes, p = 0.636).As The fecal microbiota meta-regression analyses indicated that age influenced fecal phylum microbial abundance in individuals with and without obesity . For oldThe estimated SMDs of the Bacteroidetes phylum was increased from −1.116 to −0.115 for participants aged 11 to 47 years. Furthermore, the Firmicutes phylum concentration in feces increased less in obese individuals than in nonobese individuals for older-aged participants b. For paThe estimated SMD of phylum Firmicutes decreased from 0.779 to 0.221 for participants aged 11 to 37 years. The estimated SMD of Firumicutes decreased −0.007 to −0.269 for participants aged 38 to 47 years. The meta-regression analyses of the studies suggested that age was a possible source of heterogeneity. The summary of findings for the outcomes of interest and the levels of evidence using GRADE assessment are provided . The qua2 than in those with a BMI >25 kg/m2. The systematic review included seven human clinical studies with a total of 246 obese cases and 198 normal controls and found differences in the levels of SCFAs in feces between the obese cases and nonobese controls. The findings show that individuals with obesity had higher fecal levels of acetate, propionate, and butyrate SCFAs, a finding that was more consistent in obese cases with a BMI >30 kg/mThe relationship between obesity and SCFAs produced by intestinal bacteria is not yet fully understood but can be explained by the following hypotheses. Intestinal anaerobic bacteria produce SCFAs, including acetate, propionate, and butyrate, as major end-products by fermenting indigestible polysaccharides . These SWe also compared the gut bacterial richness in obese and nonobese individuals of Firmicutes and Bacteroidetes phyla, and found that obese individuals had low bacterial abundance in feces, but the differences were not statistically significant. Our finding was consistent with a previous study showing no correlation between human obesity and the proportions of Bacteroides and Firmicutes among fecal bacteria . However2 had a higher level of total SCFAs, acetate, propionate, and butyrate without heterogeneity. The meta-regression showed that the differences in fecal microbial richness between the two groups were influenced by age. Thus, the degree of obesity and age partly account for the significant heterogeneity. We included only seven studies, some of which had a relatively small sample size. Most of the study participants were from Europe and the United States while one study was from Ghana, so our results might not be applicable to other Asian or African populations. It would be interesting to determine whether the levels of acetate, propionate, butyrate, and valerate are different between obese and nonobese individuals by sex, age, race, and diet, but the lack of data in the included studies prevented further analysis. We conducted searches based on three major electronic databases and considered only studies published in English. Some studies published in non-English languages may have been missed. Therefore, it was inevitably difficult to avoid selection and language biases in this meta-analysis. However, despite these limitations, our study has the strength of being the first meta-analysis to evaluate the relationship between SCFAs and obesity in humans, and the results of higher fecal SCFAs in obese individuals with respect to nonobese individuals are valuable. This study had several strengths and limitations. Heterogeneity was found between studies when data were pooled. The potential sources of heterogeneity might be age, measurement of specimens, diet, degree of obesity, and differences in sample size. The subgroup, sensitivity, and meta-regression analyses were used to explore the potential sources of high levels of heterogeneity. The subgroup analyses showed that individuals with a BMI >30 kg/mOur results indicate that obesity is associated with high levels of SCFAs but not gut microbiota richness at the phylum level. However, these results do not clearly explain the relationship due to the substantial heterogeneity and the limitations of the study designs. Additional randomized controlled studies are needed to clarify whether the role of SCFAs in energy metabolism or weight control is different between obese and nonobese individuals, but it is also necessary to identify additional contributors to SCFA production, absorption, and excretion in humans.


Overweight and obesity are important risk factors for type 2 diabetes (T2D). Moving towards healthier diets, namely, diets rich in bioactive compounds, could decrease the odds of suffering T2D. However, those individuals with high body mass index (BMI) may have altered absorption or metabolism of some nutrients and dietary components, including polyphenols. Therefore, we aimed to assess whether high intakes of some classes of polyphenols are associated with T2D in a population with metabolic syndrome and how these associations depend on BMI and sex. This baseline cross-sectional analysis includes 6633 participants from the PREDIMED-Plus trial. Polyphenol intakes were calculated from food frequency questionnaires (FFQ). Cox regression models with constant time at risk and robust variance estimators were used to estimate the prevalence ratios (PRs) for polyphenol intake and T2D prevalence using the lowest quartile as the reference group. Analyses were stratified by sex and BMI groups (overweight and obese) to evaluate potential effect modification. Catechins, proanthocyanidins, hydroxybenzoic acids, and lignans were inversely associated with T2D. Hydroxycinnamic acids were directly related in men. These associations were different depending on sex and BMI, that is, women and overweight obtained stronger inverse associations. The number of people with diabetes has been increasing over the past few decades and the estimations for the near future are not encouraging. Currently, 8.5% of adults have diabetes worldwide, type 2 diabetes (T2D) being the most prevalent type. People with T2D have increased odds of premature death and are more likely to have myocardial infarction or angina, stroke, kidney failure, peripheral artery disease, vision loss, and neuropathy. Therefore, T2D may be considered a global public health problem with vast economic consequences .Unlike type 1 diabetes, T2D can be prevented through different approaches, namely, exercising regularly, avoiding smoking, keeping weight under control, and adhering to a healthy diet. There is compelling evidence from prospective observational studies and clinical trials that individual nutrients, foods, and dietary patterns are crucial in the prevention and management of T2D. It is well known that plant-based diets including whole grains, fruits, vegetables, legumes, and nuts as well as moderate alcohol consumption have been associated with lowering the risk of T2D, whereas diets rich in refined grains, red or processed meats, and sugar-sweetened beverages increase the risk , and betOverweight and obese individuals are at higher risk of T2D than lean ones, therefore it seems that they would particularly benefit from polyphenol intake. However, some literature suggest that those with higher body mass index (BMI) may have altered absorption or metabolism of some nutrients and dietary components, including polyphenols ,6.Due to the heterogeneity of polyphenols, and to understand their antidiabetic properties, it is necessary to study them considering the different groups separately, because they have different absorption and metabolism . Epidemi2 who met, at least, three components of the metabolic syndrome .The present study was designed as a baseline cross-sectional analysis in the PREDIMED-Plus trial, a six-year parallel-group, multicenter, randomized, lifestyle intervention study for the primary prevention of cardiovascular disease involving 6874 participants recruited in 23 Spanish recruiting centers from October 2013 to December 2016. Eligible participants were men (aged 55–75 years) and women (aged 60–75 years) with a BMI between 27 and 40 kg/mhttp://predimedplus.com. The selection and the description of the studied sample have been previously reported [Details on the PREDIMED-Plus protocol can be found at reported . The PREAfter the exclusion of 53 participants with missing baseline dietary data and 188 with extreme energy intakes (<500 or >3500 for women and <800 and >4000 for men) , 6633 paAt baseline, participants filled out a validated 143-item semi-quantitative food frequency questionnaire (FFQ)  under thwww.phenol-explorer.eu). The validity of this particular FFQ to assess total polyphenol intake was tested in both clinical and cross-sectional studies [2) and obese (BMI ≥ 30 kg/m2), polyphenol intakes were divided in quartiles.The 143-item FFQ was also used to calculate polyphenol intake together with the Phenol-Explorer database  ≥ 6.5%, or use of antidiabetic medication at baseline, or fasting plasma glucose > 126 mg/dl in both the screening visit and baseline visit.Participants filled out a general questionnaire to provide data on lifestyle habits, education, concurrent diseases, and medication use. Physical activity was measured by a short Minnesota Leisure Time Physical Activity Questionnaire validated for the Spanish population . Height Baseline characteristics according to quartiles of total polyphenol intake are presented as means (±SD) for quantitative variables and frequencies for categorical variables. One-factor ANOVA tests were used to assess the differences between quartiles of polyphenol consumption and chi-squared tests for categorical variables.We used Cox regression models with constant time at risk and robust variance estimators to obtain the prevalence ratios (PRs) for polyphenol intake and T2D prevalence using the lowest quartile as the reference group . We ran In multivariate models, we adjusted for age (continuous), smoking status , physical activity (quintiles), and education  in model 1. In the fully adjusted model, we additionally adjusted for energy intake (continuous) as well as consumption of refined cereals and animal products (derived from the 17-point questionnaire) and of distilled beverages and liquors, sugar, soft drinks, cookies, and pastries (in g/day derived from the FFQ). All models were stratified by the recruiting center.t-tests were two-sided and p-values below 0.05 were considered significant.Interaction effect was calculated comparing the models, with and without the interaction term, with likelihood-ratio tests after estimation. We tested for linear trends across categories of polyphenol intake by assigning each participant the median value for each category and modelling this value as a continuous variable. Statistical analyses were conducted using STATA software . All The present study was conducted on 6633 participants from the PREDIMED-Plus cohort, 51.6% men, with a mean age of 65.0 ± 4.9 years. Of these, 2042 had T2D at baseline (30.8%). Mean total polyphenol intake was 846 ± 275 mg/day. Approximately 58% corresponded to flavonoids, 33% were phenolic acids, and the rest were stilbenes, lignans, and other polyphenols. The flavonoid group was mainly composed of proanthocyanidins (205 ± 175 mg/day), flavanones (86 ± 75 mg/day), flavones (72 ± 45 mg/day), flavonols (54 ± 22 mg/day), anthocyanidins (44 ± 36 mg/day), and catechins (28 ± 22 mg/day). Other flavonoid subclasses, namely, chalcones, dihydrochalcones and dihydroflavonols, theaflavins, and isoflavonoids, contributed less than 1% and were not considered in the analyses. Within phenolic acids, hydroxycinnamic acids were the main subclass (>90%) and hydroxybenzoic acids followed them with 6%. Other minor phenolic acids were also not considered. Intake of energy-adjusted polyphenols by sex and BMI group is shown in In We performed Cox proportional models with constant time to study the association between T2D prevalence and quartiles of the following main polyphenol groups: flavonoids , phenolic acids (hydroxycinnamic and hydroxybenzoic acids), stilbenes, and lignans. The results of the fully adjusted model comparing the fourth versus the first quartiles for men and women are shown in 2), and obese (BMI ≥ 30 kg/m2). In our cohort, three out of four participants were obese. The prevalence of T2D in the groups with obesity compared to the overweight groups was higher in both men (34% vs. 32%) and women (29% vs. 24%).Because weight is an important risk factor for T2D, we also performed the same analysis but dividing the population in two groups according to the BMI—overweight , proanthocyanidins and catechins showed the same association with new-onset T2D when baseline glucose levels were taken out of the model but not in the fully adjusted model. In a large, prospective, case-cohort study, Zamora-Ros et al. concluded that all flavan-3-ol monomers, including catechins, as well as proanthocyanidins of low polymerization degree were associated with a lower risk of developing T2D. As in our case, they did not find associations for flavonols, except for myricetin intake .Many studies have focused on other monomers of flavan-3-ols, especially epigallocatechin gallate, usually found in tea, grapes, and some seeds, and chocolate catechins. The antidiabetic effects of flavan-3-ols have been reported in animal and cell-culture studies, as well as several clinical studies ,19,20. DAnthocyanidins are the blue, red, and purple pigments of most fruits and vegetables, such as berries and wine. Although we only found an inverse linear trend with T2D in overweight men, results from in vitro, animal, epidemiological, and human studies have suggested that anthocyanidins might play an important role modulating T2D , even thHydroxybenzoic acids followed the same pattern as that of proanthocyanidins and catechins, showing inverse associations in overweight men and women but not in obese men. Red wine, olives, and walnuts were their principal sources in this cohort. Perhaps because they are the minor components of the phenolic acid group, they have not received much attention in previous studies. Hydroxycinnamic acids, on the other hand, accounted for more than 90% of the phenolic acid group, coffee being the main food source. In our cohort, hydroxycinnamic acid intake was associated with higher prevalence of T2D in men and almost in women. This result contradicts other studies regarding coffee and their polyphenols, such as caffeic acid, or chlorogenic acid. Large observational studies have pointed towards a significant inverse association between coffee consumption and T2D, especially with decaffeinated coffee ,26. In aStilbenes are non-flavonoid polyphenols, usually known due to its main representative—resveratrol. Red wine is by far the main source of this group of compounds, accounting for more than 90% of the intake. Stilbenes were strongly associated with lower odds of developing T2D in the PREDIMED study ; howeverLignans are phytoestrogens usually found in fiber-rich foods since they are constituents of plant cell walls. In western populations, the consumption of lignans are usually greater than isoflavones. The urinary excretion of lignan metabolites produced by the microbiota (mainly enterodiol and enterolactone) is a marker for fiber intake and whole-grain products . In our We did not find significant associations with T2D prevalence for any of the following groups: flavanones, flavones, and flavonols, although in a similar population, flavanones were inversely associated with T2D incidence . In a prWe noticed that, in our population, prevalence ratios in overweight participants were generally lower than in obese ones. These results agree with the fact that obesity is associated with lower nutrient bioavailability. Novotny et al. conducted a pilot study to investigate the pharmacokinetic response of grape polyphenols in overweight and obese vs. lean volunteers. They found higher concentrations for catechin, epicatechin, quercetin, and resveratrol in individuals with normal BMI, suggesting that obesity could compromise polyphenol absorption . A previThe exact mechanisms by which polyphenols affect T2D are still unknown. Several in vitro and animal studies have pointed out that polyphenols decrease glucose absorption in the small intestine due to the inhibition of α-glucosidase, α-amylase, and sucrase in the gut mucosa, and they also limit their reabsorption in the kidney. Other mechanisms of action are related to peripheral tissues. That includes inhibition of gluconeogenesis, adrenergic stimulation of glucose uptake, and stimulation of insulin release by pancreatic β-cells .The main limitation of the present study is the cross-sectional design, which does not allow us to assess causality, but also the estimation of polyphenol intake through FFQs, so bioavailability could not be considered. Furthermore, as in all epidemiological studies, residual confounding cannot be excluded. Finally, these results might not be generalizable to other populations. Our study has also several strengths, including the big sample size, the blinded assessment of the endpoint, the multicenter design, and the comprehensive data on dietary intake and risk factors of T2D and other potential confounders.Many research studies endorse the role of polyphenols in modulating the risk of diseases. However, there are many issues to deal with when assessing these effects such as their wide variability of structures, the difficulty of analyzing polyphenol content in foods, the interactions between them, other food components and food matrices, and the complexity of the human body .Authors should discuss the results and how they can be interpreted in the perspective of previous studies and of the working hypotheses. The findings and their implications should be discussed in the broadest context possible. Future research directions may also be highlighted.We can conclude that high intakes of some polyphenols are inversely associated with the prevalence of T2D in older adults with metabolic syndrome, these relationships being more especially observed in overweight subjects than in obese ones. However, hydroxycinnamic acids are directly associated with T2D. In that sense, randomized controlled trials would be useful to confirm the promising benefits of polyphenols for the prevention and management of T2D.


P = 0.000]. After classification into four different groups based on the time of screening for thyroid function, the increased likelihood of HDP persisted in those diagnosed with SCH in the first and second trimesters . The diagnosis of SCH in the preconception period and the third trimester was not significantly associated with HDP and other adverse perinatal outcomes. Five out of 120 (5/120) treated women (4.17%) vs. 4/45 untreated women (8.89%) developed HDP, 4/5 were treated after conception. The results indicate that during pregnancy, SCH conferred an increased risk of HDP, particularly in women diagnosed with the disorder in the first and second trimesters.Subclinical hypothyroidism (SCH) is a mild form of hypothyroidism that is common among women of childbearing age. The impact of SCH on adverse perinatal outcomes is unclear and universal screening for thyroid function before or during pregnancy is also much debated. In the present retrospective cohort study on 7,587 women from Shanghai, we assessed whether SCH was associated with adverse perinatal outcomes. The relationship between the risks of adverse outcomes and the time of screening and LT4 treatment status for SCH were also evaluated. SCH was associated with hypertensive disorders of pregnancy (HDP) [odds ratio (OR): 4.04; 95% confidence interval (CI): 1.85–8.84;  Despite the well-known deleterious effects of overt thyroid dysfunction in women of reproductive age, the impact of subclinical hypothyroidism (SCH), a mild form of hypothyroidism defined as elevated thyroid stimulating hormone (TSH) greater than the upper limit of the reference range with normal free thyroxine (FT4) levels, on perinatal outcomes remains unclear , 2. On aTo date, universal screening for thyroid dysfunction, both before and during pregnancy, is debated. The updated American Thyroid Association (ATA) guidelines published in 2017 concluded that there was insufficient evidence to make recommendations on the universal screening of thyroid dysfunction in the preconception phase or during early pregnancy . This maIn the present retrospective cohort study, we included 7,587 pregnant women to determine whether SCH is related to adverse perinatal outcomes. We also investigated the relationship between adverse perinatal outcomes and the timing of the first thyroid function test.in-vitro fertilization (IVF), multiple births, and both IVF and multiple births, were excluded. Finally, 6,157 cases were eligible for analysis . Among the remaining 6,670 cases, 348, 290, and 125 cases of analysis .According to the earliest time of thyroid function testing, the subjects were categorized into 4 different groups, namely preconception (within 2 years before pregnancy), first trimester (<13 weeks), second trimester ≥13 and <28 weeks), and third trimester (≥28 weeks).The present study established trimester-specific reference intervals of thyroid function according to the recommendations of the National Academy of Clinical Biochemistry  and the 4 above the trimester-specific reference interval (97.5th percentile), excluding gestational hyperthyroidism; (2) subclinical hyperthyroidism: serum TSH concentration below the statistically defined lower limit of the trimester-specific reference range with serum FT4 concentrations within trimester-specific reference ranges; (3) overt hypothyroidism: TSH concentration above the trimester-specific reference interval (97.5th percentile), with a decreased FT4  or TSH concentration above 10.0 mIU/L irrespective of the level of FT4; (4) hypothyroxinemia: normal TSH concentration (between the 2.5th and 97.5th percentiles) in conjunction with FT4 concentrations in the lower 10th percentile of the reference range; (5) SCH: TSH higher than the 97.5th percentile and FT4 between the 2.5th and 97.5th percentiles; (6) euthyroidism with thyroid peroxidase antibody positivity (TPOAb+): both serum TSH and FT4 within the reference range (2.5th−97.5th) and anti-TPOAb levels higher than the upper limit of the reference value provided by the test kit (60 IU/mL in this study); and (7) euthyroidism with thyroid peroxidase antibody negativity (TPOAb–): both serum TSH and FT4 within the reference range (2.5th−97.5th) and anti-TPOAb levels lower than the upper limit of the reference value provided by the test kit. In current study, we focused on SCH; euthyroid and TPOAb– women were considered as the reference group  overt hyperthyroidism: serum TSH <0.1 mIU/L and FTThe adverse perinatal outcomes were based on the diagnoses at discharge as per the medical records. We acquired data with a focus on the following adverse maternal and neonatal outcomes: gestational diabetes, hypertensive disorders of pregnancy (HDP), intrahepatic cholestasis of pregnancy (ICP), preterm labor, placenta previa, preterm premature rupture of membranes (PROM), fetal growth restriction (FGR), fetal distress, fetal death, low Apgar score (<7) at 5 min, low birth weight , and macrosomia . Factors that potentially impact the relationship between SCH and perinatal outcomes were chosen as potential confounders. We defined maternal age, gestational age, race, gravidity, parity, and delivery modality as possible confounding factors based on data from both, previous studies and our cohort.t- and chi-squared tests were used to compare continuous and categorical variables, respectively. The risks of adverse outcomes in patients with SCH were determined by the chi-squared test and were presented as odds ratios (ORs) with 95% confidence intervals (CIs). After adjusting for confounders, multivariable logistic regression analysis was used to assess the associations between maternal SCH and obstetric outcomes. Statistical analysis was performed using the SPSS 19.0 software  package. P < 0.05 was considered to be statistically significant.All data were expressed as means ± standard deviations or numbers and percentages. The Student's Among 6,157 eligible cases, the overall incidence of SCH was 2.68%; the highest and lowest incidences of SCH were observed in the second  and first  trimesters, respectively . Notablyn = 165) and CON  groups. Prior to grouping by different prenatal stages, race (P = 0.03) was found to be statistically different between the two groups (P = 0.04) and parity (P = 0.03) in the preconception period. In the first trimester, gravidity (P = 0.001) was significantly different between the two groups. No differences were found in the general characteristics between the SCH and CON groups in both, the preconception and third trimester periods.The general demographic characteristics of the participants are shown in o groups . After gP = 0.001) and PROM  were significantly higher in the SCH group. However, after controlling for confounding factors, statistical difference between the two groups was noted only for HDP .The adverse perinatal outcomes in the SCH and CON groups are demonstrated in P = 0.01, and OR: 3.66; 95% CI: 1.07–12.57; P = 0.03, respectively)  , 4. ThisIn the present study, the overall incidence of SCH was 2.68%. In total, 5/120 treated women (4.17%) vs. 4/45 untreated women (8.89%) developed HDP, and from the treated women 4/5 were actually started on treatment late in pregnancy. Except for race, the demographic indices were similar between the SCH and CON groups. SCH in pregnancy was associated with a significantly increased risk of HDP, particularly in those who were diagnosed with SCH in the first and second trimester. Conversely, in women who were tested for thyroid function before conception and the third trimester, a detrimental effect of SCH on the risk of maternal and neonatal outcomes was not observed.The diagnostic criteria for SCH in pregnancy have changed over the years and vary between countries. Since the daily intakes of iodine, prevalence of thyroid autoimmunity, genetic backgrounds, and environmental factors vary between different populations, and the gestational age affects TSH levels, it is crucial to use a laboratory- or population-based trimester-specific TSH reference range for the diagnosis of SCH in pregnancy . AdvanceReports suggest that SCH during pregnancy is associated with adverse perinatal outcomes, including miscarriage, preterm delivery, gestational diabetes, eclampsia, PROM, intrauterine growth restriction, and low birth weight , 14. DatHDP, including preeclampsia, gestational hypertension, chronic hypertension, and superimposed preeclampsia, has been shown to be a leading cause of maternal and perinatal morbidity and mortality in a multitude of large epidemiological studies worldwide –23. In oIn addition to the short-term impact on the mother and fetus, HDP also leads to an increase in the risk of other diseases later in life, including anxiety disorders in adolescent offspring and maternal cardiovascular diseases after pregnancy , 28. So Compared to the adverse consequences in later life, screening for SCH in pregnancy is expected to be a cost-effective strategy. In the USA, analysis for cost-effectiveness has demonstrated that for every 100,000 pregnant women screened for SCH, $8,356,383 is saved, and 589.3 QALYs  are gained . AnotherThe large sample size and the inclusion of women in the preconception period are some of the strengths of the present study. However, it also has some limitations. First, it was a retrospective study; therefore, the data analyzed were from women who had already delivered. Consequently, pregnancy loss caused by various factors (including SCH) before delivery was not considered during analysis. Second, the study focused on two time points, namely, that of the earliest thyroid function test and the time of delivery. Although we were able to identify the women who received LT4 treatment, detailed information (drug dosage and effect) on the specific interventions for SCH were not available, since at our center, most women with abnormal thyroid function are referred to endocrinology clinics for optimal treatment. Third, after grouping, the number of HDP cases in each SCH sub-group during pregnancy was very small; this may have reduced the power of the test. Further prospective trials with larger samples are needed to elucidate the relationship between SCH in the preconception period and perinatal outcomes in the Chinese population. The role of LT4 supplements also needs further evaluation.SCH during pregnancy, particularly when detected in the first and the second trimester, is associated with an increased risk of HDP, compared to euthyroid TPOAb- controls. Our findings suggest that routine thyroid function screening is necessary during pregnancy, particularly during the first and second trimesters.The datasets generated for this study are available on request to the corresponding author.This study complies with the guidelines of the Declaration of Helsinki. All data were processed anonymously.M-QW, JL, Y-QW, YY, C-HY, and JH contributed to study design and acquisition of research data. M-QW and JL conducted the data analysis. M-QW drafted the manuscript. All authors contributed to improvements of the manuscript for important intellectual content and approved the final version for publication.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


We investigated the association between occupational noise exposure and the risk of elevated blood pressure and hypertension by stage in young adults.high (75 dBA noise exposure for more than 4 hours per day) or low, and measured blood pressure (mmHg) and categorized participants by hypertension stage . We applied adjusted logistic regression models to identify associations with hypertension risk, and we further examined the noise-BMI, noise-gender, and noise-residence interactions on hypertension risk in separate models.We utilized 124,286 young adults (18–40 years) from the Project ELEFANT study. We categorized occupational noise exposure as p = 0.0009), in Stage 1 hypertension , and in Stage 2 hypertension . Likewise, noise exposure-BMI interaction was consistently positively associated with increases in blood pressure in participants with elevated blood pressure , in Stage 1 hypertension , and in Stage 2 hypertension . The noise exposure-male interaction showed higher risk for hypertension compared to the noise exposure-female interaction in participants with elevated blood pressure , Stage 1  and Stage 2 hypertension . Finally, we found that noise exposure-urban interaction was consistently associated with an increase in blood pressure in elevated blood pressure  and in Stage 2 hypertension .High occupational noise exposure was associated with increases in blood pressure among participants with elevated blood pressure (Estimate = 0.23, 95% CI: 1.09, 1.46,  Noise is a highly prevalent environmental exposure in the United States , in EuroAccording to the WHO, ischemic heart disease, stroke and hypertensive heart diseases were the leading causes of death in 2015 . In thisIn this study, we investigated the effect of chronic occupational noise exposure upon the development of hypertension in young adults. We utilized 124,286 individuals (18–40 years) from within Project Environmental and LifEstyle Factors iN metabolic health throughout life-course Trajectories (ELEFANT) to estimate risk of hypertension by stage  with noise exposure, and examined the interaction of noise-BMI, noise-gender, and noise-residence on hypertension risk in separate models. We report that noise exposure is associated with increased blood pressure in elevated blood pressure, Stage 1 and Stage 2, and displayed interaction with BMI, gender and residence.n = 48,762); Young ELEFANT ; and Elderly ELEFANT  [n = 124,286). The protocol of this study was approved by the Institutional Review Board of the Tianjin Medical University, and participants gave written informed consent prior to participation in the study.Project ELEFANT is a newly developed population study based in Tianjin, China that comprises three population studies: Baby ELEFANT  . CompletSystolic blood pressure  and diastolic blood pressure  were measured according to criterion of the JNC 7  . Blood pTo assess the occupational noise exposure of the participants, we constructed questionnaires to independently capture the occupation of the individual and their level of noise exposure (high/low). High noise exposure was defined as exposure to levels higher than 75 dBA for more than four hours per day. The participants reported more than 100 different types of occupation, which were categorized into three groups based upon The International Standard Classification of Occupations (ISCO) . In our We followed Chinese guidelines to define BMI categories, with BMI below 24 defined as normal weight, between 24 and 28 as overweight, and higher than 28 as obese .p is the probability of having one of the stages of the hypertension. All analyses were performed using SAS 9.4 .The relationship between noise exposure and blood pressure as continuous variables was investigated using multivariate regression analysis. The relationships between each blood pressure classification  with noise exposure were evaluated using logistic regression analysis. In both the logistic and regression models, we adjusted the model with the following covariates: age (continuous); BMI (continuous); gender ; occupation (3 categories); residence ; education (basic/higher); smoking (yes/no); number of cigarettes per day; drinking (yes/no); and noise exposure (high/low). We fitted a logistic regression model to investigate all interaction and all the models were adjusted with the same variables.We analyzed 118,143 participants who were aged between 18 and 40, and who had complete data for all covariates of the adjusted model. The basic characteristics of participants are shown in p<0.0001, t-test). The mean DBP of participants with high noise exposure levels (77.07 mmHg) was significantly higher than those with low levels of exposure (74.91 mmHg) . SBP and DBP were both significantly associated with noise exposure in the adjusted model . In the multivariate linear regression model, SBP  and DBP  were increased with high exposure , in Stage 1 hypertension , and in Stage 2 hypertension  (The odds ratio (OR) of elevated blood pressure with high occupational noise exposure was 1.77 , 1.45  for Stage 1 hypertension, and 2.72  for Stage 2 hypertension . In this1, 1.73) . The ORs1, 1.73) .p<0.0001), Stage 1 hypertension , and Stage 2 hypertension  (p<0.0001), Stage 1  and Stage 2 hypertension  (p<0.0001) and Stage 2 hypertension , with odds ratios of 1.38 and 1.55 respectively  or overweight/obese (BMI≥24). The noise exposure-BMI interaction was consistently positively associated with an increase in blood pressure in participants with elevated blood pressure  . Thus, t<0.0001) . Analysi6, 7.77) . The noi6, 7.77) . Finallyectively .In this study, we investigated the association between occupational noise exposure and hypertension by stage in young adults from the Project ELEFANT study. Additionally, we analyzed the interaction of BMI, gender and residence with noise exposure on blood pressure. Our results revealed a consistent pattern of increased risk of hypertension by stage  and higher blood pressure among individuals with high levels of occupational noise exposure, with greater effect in overweight/obese individuals and men.While the relationship between noise exposure and hypertension and/or blood pressure has been extensively investigated, the results to date have been inconsistent. A meta-analysis of 43 studies reported that 5 dB(A) of occupational and traffic noise exposure were associated with a relative risk of hypertension of 1.14 and 1.26, respectively . Recent While occupational noise has been reported to be associated with hypertension, and other forms of heart disease, the mechanisms underpinning these associations have not yet been elucidated. However, evidence from the study of noise exposure upon blood pressure may provide insight into these processes. Acute noise exposure has effects on the endocrine and sympathetic nervous systems that result in physiological changes such as increased heart rate, blood pressure, vasoconstriction, production of stress hormones . Noise mNR3C1 has been reported in response to different forms of stress [Bdnf, Comt, Mc2r) DNA methylation changes in the brain response to both short-term and long-term noise exposure [Epigenetic mechanisms frequently mediate the effects of environmental exposures in relation to health and disease. Alterations in DNA methylation have been implicated with many diseases including cancer and CVD. Importantly, several studies have demonstrated that epigenetic changes in response to different stresses including disruption of circadian system, chronic social stress, and famine stress from the Dutch Hunger . In partf stress , 30. In exposure . These eexposure .There are several limitations in our study. Firstly, more precise measurement of noise exposure would potentially increase the power and accuracy of analysis, but this would have been prohibitively expensive in a large cross-sectional study such as our own. It is also known that noise exposures are correlated with air pollution exposure, such as via traffic. In this study, we were unable to account for ambient and traffic air pollution, although we were able to adjust for residential area and occupation. Finally, due to the lack of standard and insightful measures of noise exposure , our study has suffered from the same inherent difficulty as others in describing exposure levels. However, it should also be noted that our study has several key strengths. Most notably, we have been able to leverage a very large cohort of young adults who are otherwise healthy and provide sufficient statistical power to accurately analyse the impact of exposure upon blood pressure and risk of hypertension. Furthermore, due to the well-characterized nature of the cohort, we were able to adjust for a large number of potential confounders to more precisely study the effect of occupational noise exposure.In summary, our study has revealed that occupational noise exposure is associated with higher risk of elevated blood pressure and hypertension in young adults, and we have demonstrated an interaction of noise with gender and BMI. Further work is required to investigate the biological mechanisms that may explain these associations.