Attaran argues that five years into the Millenium Development Goals project, problems with measurement mean that often we cannot know if true progress towards these goals is occurring. In September 2000, 147 heads of state met at the United Nations (UN) headquarters—the largest such gathering ever—to resolve action on the most pressing problems of humanity and nature ). Details of the targets subsumed by goal eight and the various indicators for all the goals or targets can be found in .Goal 1: Eradicate extreme poverty and hunger • Reduce by half the proportion of people living on less than a dollar a day• Reduce by half the proportion of people who suffer from hungerGoal 2: Achieve universal primary education • Ensure that all boys and girls complete a full course of primary schoolingGoal 3: Promote gender equality and empower women • Eliminate gender disparity in primary and secondary education preferably by 2005, and at all levels by 2015Goal 4: Reduce child mortality • Reduce by two thirds the mortality rate among children under fiveGoal 5: Improve maternal health • Reduce by three quarters the maternal mortality ratioGoal 6: Combat HIV/AIDS, malaria, and other diseases • Halt and begin to reverse the spread of HIV/AIDS• Halt and begin to reverse the incidence of malaria and other major diseasesGoal 7: Ensure environmental sustainability • Integrate the principles of sustainable development into country policies and programmes; reverse loss of environmental resources• Reduce by half the proportion of people without sustainable access to safe drinking water• Achieve significant improvement in lives of at least 100 million slum dwellers, by 2020Goal 8: Develop a global partnership for development This September, the heads of state will gather again for the Millennium +5 Summit to assess the five-year progress of the MDGs. They will find that the MDGs have become all-important, not just within the UN, but also as the zeitgeist of the global development enterprise. As Professor Jeffrey Sachs, Director of the UN's Millennium Project, has declared, “To the extent that there are any international goals, they are the Millennium Development Goals”.But is it wise to elevate the MDGs to the pedestal where they now sit? Could it be, despite an appearance of firm targets, deadlines, and focused urgency, that the MDGs are actually imprecise and possibly ineffective agents for development progress?In this article, I argue that many of the most important MDGs, including those to reduce malaria, maternal mortality, or tuberculosis (TB), suffer from a worrying lack of scientifically valid data. While progress on each of these goals is portrayed in time-limited and measurable terms, often the subject matter is so immeasurable, or the measurements are so inadequate, that one cannot know the baseline condition before the MDGs, or know if the desired trend of improvement is actually occurring. Although UN scientists know about these troubles, the necessary corrective steps are being held up by political interference, including by the organisation's senior leadership, who have ordered delays to amendments that could repair the MDGs . In shorWhat makes the MDGs attractive is their concreteness. For example, the MDG to eradicate extreme poverty subsumes a “target” to “halve, between 1990 and 2015, the proportion of people whose income is less than $1 a day”, which in turn subsumes “indicators”, one of which is to measure income based on purchasing power.Knowing that, worldwide, 28% of people in 1990 had purchasing power below $1 a day gives rise to a benchmark: that in 2015, fewer than 14% of people should be so destitute . Currently, East Asia is on track; sub-Saharan Africa is not . Such deIt is harder to get sufficient and reliable data for the health MDGs. Even the most basic life indicators, such as births and deaths, are not directly registered in the poorest countries. Within this decade, only one African country (Mauritius) registers such events according to UN standards . WithoutAccordingly, most of the available data on the health MDGs come from methods of estimation, censuses, specialised household surveys, or all of these together.There are many—too many—household surveys. In the public-health field, the best known are the Demographic and Health Survey (DHS) and the Multiple Indicator Cluster Survey (MICS), funded mainly by the United States and United Nations Children's Fund (UNICEF), respectively . In addiDonor's [sic] support is not always appropriately coordinated. There are many examples of duplicated or conflicting data collection activities. This lack of coordination does not only causes [sic] a huge waste of funds, it also put [sic] a high burden on national statistics offices. In the past few years, significant progress has been made to identify synergies among different survey programs or to develop common questionnaire modules, and to conduct joint data collection activities. But there is certainly room for much more cooperation. All of this is true, but even within the UN, different agencies jostle counterproductively for data. For example, in 2002, the WHO launched a new World Health Survey in over 70 countries to compete with the longer-running DHS and MICS [10]. Justified as a “sound basis for evaluating progress towards the millennium development goals”, instead the WHO's new survey tied up the few qualified statistical staff in the poorest countries [11]. Three years later (at the time of going to press), the new project has yet to publish a single dataset. Yet household surveys are serviceable but crude tools. Even with a simple question, such as about a child's birth weight, people's answers only roughly approximate the truth, as would be measured by weighing on a scale [13]. Other survey questions are so technical that no layperson can answer them accurately. MICS, for example, asks parents if their child's anti-malaria bed net was “ever treated with a product to kill mosquitoes”: an accurate answer depends on the type, dose, and date of insecticide treatment, and whether the local mosquito species carry insecticide resistance genes [14]. Because household surveys do not announce these or other sources of error, one can easily have false confidence in them. For example, many MICS survey reports present their findings as single-point estimates, without any of the usual qualifiers of data inaccuracy or quality, such as statistical confidence intervals or significance tests .In short, there are many sources of data on the MDGs. When those sources suffice to reveal statistically significant trends in the MDGs, then all is well, and it is possible to make conclusive statements: that the MDGs are being met, or that the MDGs are being missed. But, as the case studies below illustrate, such certainty is highly elusive.MDG 6, Target 8, pledges to “have halted by 2015 and begun to reverse the incidence of malaria”. The malaria MDG overlaps with a somewhat earlier (1998) WHO-led goal known as Roll Back Malaria (RBM), which aims “to halve malaria-associated mortality by 2010 and again by 2015” [16]. Even though the MDG and the RBM goal are only quasi-consistent with one another, the UN allows them to coexist, and UN communications often mention both [16]. Accordingly, both are discussed here.Yet with double attention on malaria, and the head start afforded by RBM, the UN still is unable to make an official pronouncement on the progress of its malaria goals. The WHO and UNICEF write that it is “too soon to determine whether the global burden of malaria”, meaning both incidence and mortality, “has increased or decreased since 2000” [16].Too soon? RBM is in its seventh year, and past the halfway mark of its 2010 deadline. The only two possible reasons not to know if malaria has increased or decreased are that the UN either (i) did not encourage timely measurements or (ii) chose indicators—malaria incidence and mortality—that are essentially immeasurable.Actually, both are true. What follows is a cautionary history.In 2002, the British government commissioned an independent evaluation of the UN's malaria efforts. It did so because it was the largest financier of RBM, and because of a perception that there was insufficient alignment between the efforts of the UN agencies and malarious countries. On the subject of measuring progress, the evaluators wrote: The main problem affecting…data collection efforts…has been that an overly complex and insufficiently prescriptive approach has been taken. There has been a failure to clearly define goals and priorities of the [measurement] strategy at the global and regional levels....Too many indicators are proposed. Too many sources of data are suggested. Insufficient guidance is given to countries on data collection and methodology….Some countries are measuring one thing, some countries are measuring another….In some cases, data are being collected without any systematic and scientific sampling methodology, and so are essentially meaningless and impossible to interpret. [17]This unsparing criticism points to two problems, which although they pertain to RBM, often apply with equal force to the malaria and other MDGs. The first problem concerns the lack of a baseline: it is impossible to retrospectively measure worldwide  malaria incidence and mortality existing at the inception of the RBM goal or the MDG, when the data from that era are universally acknowledged to be poor [18]. Without knowing the original condition, it is futile to stipulate either “to halve” malaria mortality by 2010 or “to halt” malaria incidence by 2015. Such words have no meaning where the baseline is mysterious.The second problem concerns the unsuitability of the indicators: both malaria incidence and mortality are so crudely measured by household surveys and most countries' health records that, essentially, they are immeasurable. The UN's malaria monitoring group agrees, writing that “malaria-specific mortality should not be monitored routinely, as this can not be measured easily in malaria-endemic Africa” [19]. Yet the UN often ignores such warnings, even when they are timely, explicit, and the opinions of its own scientists. It was only two months after WHO scientists wrote that “it will not, in general, be possible to measure the overall incidence rate of malaria” that the UN chose the incidence rate as the mainstay of the malaria MDG [20].The legacy of unfortunate decisions now leaves malaria risk mapping as the only feasible way to estimate (not measure) malaria incidence and mortality. The principle is to superimpose a map of a population onto a map of malaria intensity, although, in practice, the limitations include malaria maps from the 1960s and too few demographic surveillance sites to accurately measure and calibrate incidence and mortality risks . The WHO has been slow to use risk mapping, probably because it fears public criticism when, inevitably, the current estimates of malaria severity must be revised upward .Accordingly, years after the withering external evaluation, the UN neither has achieved convincing measurement or estimation of malaria incidence and mortality, nor has it abandoned those as the key indicators of progress. Both the RBM goal and the malaria MDG are today immeasurable.MDG 5, Target 6, pledges to “reduce by three quarters, between 1990 and 2015, the maternal mortality ratio” . Both the number of such deaths and the number of births are used to calculate the maternal mortality ratio . However, it is exactly in the poorest countries where the maternal mortality problem is severest that the data about deaths and births are least satisfactory. Vital registration would help, but few developing countries, accounting for 24% of the world's live births, have complete data . DirectlTherefore MMR must be estimated. The current method is crude, and uses regression modelling based on partial vital registration, censuses, household surveys, and other inputs [27]. The outputs are a point estimate for MMR in each geographic region, surrounded by an educated guess  of the lower and upper range in which the point estimate could lie.Accordingly, the most recent (2000) published estimate for MMR worldwide is 400 maternal deaths per 100,000 births, within an unscientific, best-guess range of perhaps 210 (low) to 620 (high) [28]. Estimates for the MDG baseline year (1990) are similarly vague [29].Without a statistically robust estimate for MMR in the baseline year, or in later years, nobody knows whether worldwide MMR has increased or decreased since 1990, other than in a “handful of countries” [26]. The limitations of current estimation techniques are so profound that UNICEF and WHO scientists warn that “it would be inappropriate to compare the 2000 estimates with those for 1990…and draw conclusions about trends” [28].Thus, 11 years after the Cairo Conference first set an explicit target to reduce MMR by 75%, the UN neither has achieved measurement of MMR, nor has it heeded the warnings of its own scientists that MMR is basically immeasurable. The MDG carries that mistaken goal forward to 2015, and the impossibility of measuring and demonstrating success is certainly preordained.MDG 6, Target 8, pledges to “have halted by 2015 and begun to reverse the incidence of…major diseases”, which the UN has interpreted to include TB .Fortunately, the MDG indicators provide for some simpler alternatives: TB disease prevalence and deaths (Indicator 23), and the proportion of TB disease cases detected and cured using a WHO-recommended treatment called “directly observed therapy—short course” . The TB prevalence and case detection indicators are directly measurable, but, ironically, the WHO does not actually measure them. Instead, it uses a unique, arguably outdated estimation method.Nobody can say with scientific confidence what the actual trends for TB are.In the WHO's method, the only true measurement is the number of new, sputum-positive TB cases that are detected and notified to the authorities for treatment with DOTS. To estimate the case detection rate, the WHO divides that number of notified TB cases (the numerator) by an estimate of at-large case incidence (the denominator) [32]. Further, the WHO obtains case incidence from “an independent estimate of the case detection rate” [33]. In effect, the WHO's two estimates are circular and lack definite meaning, for each estimate draws upon the other estimate. Further, the WHO bases this estimation process on inputs that are not always rigorous, and the inputted data are often obtained from collective opinion rather than measurement [33].Accordingly, it is impossible to state the actual trends in TB disease with any degree of statistical confidence. The WHO's best guess is that its estimates “typically range from −20% to [+]40%” in accuracy [32].Others have criticised the circular estimation technique. The WHO's former director for evidence argues that “essentially no empirical basis exists to assess the trend in case detection in regions where tuberculosis is most prevalent, including sub-Saharan Africa” [34]. He calls the WHO's trend estimates “serial guessing” [34]. Certainly, the WHO's leading assumption (known as the “Styblo rule” [35]) has infrequently been tested in Africa, where TB is accelerated by an unparalleled HIV/AIDS epidemic. The WHO's own scientists concede that it may no longer apply there [32].Nevertheless, the WHO maintains that where access to DOTS treatment is extensive—that is, not in Africa—its estimated case detection rates are an adequate guide to true TB trends. This is debatable: in China, which is the WHO's finest DOTS success, actual measurements (not estimations) of TB prevalence corroborated the WHO's case detections less well than expected [36].The best solution now proposed in the scientific literature would redefine the case detection rate, based on measuring true TB prevalence by widespread radiographic or microscopic surveys [31]. Although similar prevalence measurements have been the cornerstone of East Asia's successful attack on TB, the WHO resists changing from estimation to true measurement [37]. As a result, nobody can say with scientific confidence what the actual trends for TB are or whether the TB MDG is on track.The above case studies could leave the dismal impression that all time-limited development goals are immeasurable, lack baseline data, and imply trends having no scientific meaning. Not quite. There is a happy exception: MDG 4, Target 5, which reads to “reduce by two thirds, between 1990 and 2015, the under-five [child] mortality rate” . Conversely, in Zimbabwe during 1988–1999, the U5M rate deteriorated 44% [38]. Unlike other MDGs where such changes are, to put it bluntly, only guessed at, these trends in the U5M rate are properly measured and, importantly, are scientifically meaningful, with confidence intervals that reveal the accuracy and quality of the underlying data. Just by keeping the current DHS technique, and interviewing about 7,000 women per country every five years, it is possible to reliably detect either a 15% gain or loss in the U5M rate with scientific confidence.There is an invaluable and gratifying lesson to draw from the U5M case study: if the UN sets an MDG target that is practical to measure (most are not), and the measurement technique for that MDG target is suitable (most are not), and measurements are taken at the baseline year and in subsequent years (they rarely are), it is then possible to measure the state of the world's health reliably and accurately, and with excellent scientific confidence regarding the trend. In short, it becomes possible to know, not just to guess, if the MDGs are on track or not—even in Africa.I did not write this paper to doubt the moral necessity of investing more money and political capital in global development; that is unarguable, and it would be reprehensible to use these arguments to seed those doubts.Instead, I hope to open an important debate, unable to be fully answered by this paper, on a hitherto almost unexplored question: is the world better off with or without the MDGs and similar UN-sponsored, time-limited, quantitative development goals? The answer to that question must be sought without pro-UN or anti-UN ideology, but with awareness that there are two prongs to consider: (i) whether such goals are interpreted so as to advance the dignity and well-being of the large number of people who live in extreme poverty , and (ii) whether such goals advance the reputation of the UN and the global development establishment. I believe the MDGs risk trouble on both fronts.Viewed objectively, it must be agreed that the MDGs palter. The health goals for 2015 sound quantitative, but for most of them, their quantification is irretrievably flawed. The trends that the health goals allude to are either immeasurable or were not measured properly from the 1990 baseline year onward. This is not an extraordinarily controversial conclusion: recall that in each of the cautionary examples discussed—malaria, maternal mortality, and TB—the UN's own current or former staff have said that the trends are immeasurable or lack baseline data.Short of abandoning the MDGs, the better option is to amend the goals, targets, or indicators—all three levels of the hierarchy—to be feasibly measurable.Unfortunately, the UN leadership has, to date, delayed this option. In a September 2004 memo, one year ahead of the Millennium +5 Summit, the UN's Deputy Secretary General instructed the organisation's experts in charge of the MDG statistics with the following:The [Millennium +5 Summit]…should not be distracted by arguments over the measurement of the MDGs—or worse, over different numbers being used by different agencies for the same indicator…. [P]roposals for modifications of definitions or new indicators will only be considered formally after the [Millennium +5 Summit]… as any changes at this stage would only distract from the result that we would like to achieve. The Deputy Secretary General's order interferes with and shows a profound disrespect for the scientific process—a process that fundamentally is not “distracted by arguments” nor disturbed by “different numbers”. On the contrary, intellectual arguments between scientists are essential for devising new methods of measurements for the MDGs, so that they in turn yield more accurate numbers about the extent and causes of extreme poverty.By suppressing proposals to amend the MDGs ahead of the Millennium +5 Summit, the UN leadership discarded the only timely opportunity to win high-level political support for truly measurable, scientifically meaningful goals. While the Deputy Secretary General plans “a process that will consider recommendations regarding refinements” to the MDGs, the process will commence only after this September's summit . As a reSome may disagree with my emphasis on measurement and timelines. One anonymous peer reviewer of this paper wrote that while measuring the MDGs is “of concern for epidemiologists and others”, my interpretation “misses the point” because the purpose of the MDGs is merely to be exhortatory. “The MDGs are not a measuring exercise”, wrote the reviewer, but instead are a “common vision of what matters most for improving the lives of people in poor countries”.This sort of thinking, although widespread among development professionals, is neglectful towards people living in extreme poverty. Neglect occurs when one touts the MDGs for the “common vision” of, say, reducing maternal mortality, while being indolent about measurements to prove mortality is genuinely decreasing. That formulation values consensus about helping pregnant women, ahead of certainty about helping pregnant women—an outcome that, if they knew about it, the women could easily find ideological and dehumanising.Further, the notion that the MDGs are merely exhortatory discriminates against the world's poorest people. Imagine if European or American leaders, taking aim at poverty in their own countries, set quantitative goals to reduce unemployment or teen pregnancy—only to declare the unemployment and teen pregnancy rates were “not a measuring exercise”. Most people would abhor the dishonesty, for obvious reasons.But if it is shameful, as I believe, to interpret the MDGs as merely exhortatory, imparting no standards of performance, the converse error also exists: to interpret the MDGs as all-encompassing and imparting too many standards of performance.The latest fashion, exemplified by the UN Millennium Project, is to treat the MDGs as catch-alls or tautologies for development itself. In a list entitled “Interventions by MDG Target”, the UN Millennium Project recommends to build “roads” or “transport infrastructure” for all of the following MDG targets: primary education, hunger, gender equality, water and sanitation, child mortality, and, of course, malaria, maternal mortality, and TB [39]. Electricity, slum upgrading, and education are similar panaceas.Definitely roads or electricity matter to holistic development, but justifying those under the cover of goals expressly for child mortality or malaria, makes goal-setting seem pointless. Worse, such justification sounds dishonest—a camouflage job. It is no wonder that with the MDGs subordinated into empty vessels for tenuously related interventions—subordinated into, as Professor Jeffrey Sachs says, just “any international goals”—there is resistance to measure the progress of the specific goals, targets, and indicators with rigor and precision .The MDGs could turn from opportunity to liability.I believe that without thoroughgoing action to change the current scenario see , the MDG• Convene an external (non-UN) scientific peer review to examine the goals, targets, and indicators to ascertain whether the desired trend of improvement in each is, with current data, measurable or estimable at scientifically accepted levels of accuracy and statistical significance.• For those goals, targets, or indicators measurable by household surveys, choose only a single survey instrument; determine the minimum sample size needed to detect favourable or adverse trends with statistical significance; conduct the survey at regular intervals; and make all the micro-level data fully public, so independent scientists can replicate the UN's conclusions. Eliminate the many superfluous household surveys now in use.• For those goals, targets, or indicators not measurable by household surveys, institute sample surveys (“mini censuses”) by creating a large number of new demographic surveillance sites in various countries. The Canadian-funded Tanzania Essential Health Interventions Project is a superb example .• For those goals, targets, or indicators that are not measurable by any practical means, first consider to amend them, and if that is not possible, abandon them .• Within 18 months, hold a high-level UN-sponsored event at which governments ratify final actions for all the above. Have those actions be developed by external scientists and given to the Deputy Secretary General directly.More thoughtful and timely action for the sake of these institutions, and, needless to say, the millions of people who shall live—or die—with the success or failure of the MDGs, is only wise.


By 2010, chlorofluorocarbons (CFCs) will be banned globally because of their adverse impact on the planet’s protective ozone layer. One industrial activity that has been significantly impacted by this ban is the manufacture of plastic foams—lightweight alternatives to solid plastic that are valued for their flexibility and ability to insulate, as well as their cushioning ability and (in marine applications) enhanced flotation.2] trapped in it, but if you remove the pressure, you get fizz. With plastic, you get foam.” The resulting plastic foam can be exceptionally lightweight, given its size and application.Plastic foams are created by combining two chemicals that would otherwise form a solid plastic, or by melting an existing solid. A third substance, often a CFC, is then added as a “blowing agent.” This agent vaporizes at the reaction temperature, releasing gas bubbles into the molten plastic. “It’s much like soda,” explains Gordon Nelson, a professor of chemistry and dean of the Florida Institute of Technology College of Science and Liberal Arts. “Soda has carbon dioxide .Today, the goal of the plastic foam industry is to make a material that remains lighter than solid plastic but has many of the same qualities of durability and flexible rigidity as the solid version, and to do so without having to rely on ozone-depleting gases. A team led by L. James Lee, a professor of chemical engineering at The Ohio State University, is pursuing one approach that relies on clay nanoparticles for strength and the green chemist’s old friend—supercritical COA number of researchers have been pursuing various types of nanoparticles as strengthening agents for plastic foams, while others have been looking at different substitutes for the banned CFCs; Lee, along with fellow associate chemical engineering professors Kurt W. Koelling and David L. Tomasko, decided to tackle both aspects at once. His ultimate goal—a lightweight, environmentally friendly plastic foam that may one day replace solid plastics in some applications.2 was a logical alternative to ozone-depleting CFCs. “Supercritical CO2 is a pretty benign substance,” he says. “And it’s neither difficult to make and use, nor is it expensive. Additionally, we’re not generating new carbon dioxide, merely using what’s available atmospherically, which lessens the impact still further.”According to Lee, supercritical CO2 is that under conditions necessary to reach supercritical status, the gas becomes a liquid, which mixes more easily with the molten plastic than a solid or gas. Lee says the optimal conditions arrived at in his experiments—temperatures just above 31°C and pressures of about 1,100 pounds per square inch—are easily achievable with current technologies. These results were reported in the 16 October 2003 issue of Advanced Materials.Lee says another advantage to supercritical COAnd while most structural-grade plastic foams contain bubbles close to several hundred micrometers across, Lee’s process generates bubbles as small as 5 micrometers in diameter. According to Nelson, the bubbles must be small and uniform, or foams with less desirable qualities will result. “Smaller equals nicer consistency and better insulating properties,” he says. “Larger bubbles can alter the physical and thermal properties of the foam.”2: “Carbon dioxide is a low-cost blowing agent, but its solubility is low, so if you want it diffused throughout the polymer, you need to keep it under pressure,” he says. “That will obviously raise the cost for industry.” Owens Corning is currently looking for a viable substitute for its blowing agent of choice, the CFC chlorodifluoroethane.There is one obstacle, however, according to Roland Loh, a global applications specialist for plastic foam manufacturer Owens Corning and principal investigator in the company’s search for environmentally benign nanocomposite foam products, and that is one particular property of CO2 in diffusing out of the polymer.Lee admits that’s one of the aspects of the new technology still to be addressed. “The good thing about CFCs is that they dissolve better and diffuse out more slowly. Carbon dioxide is a small molecule, so it diffuses out more quickly, making it difficult to control density,” he explains. That’s one area where he and his colleagues believe the clay nanoparticles will help—by acting as a diffusion barrier, to slow the progress of the supercritical COThe addition of clay nanoparticles—the second aspect of Lee’s process—performs several critical functions in addition to improving the mechanical properties of the polymer. The clay also acts as a flame retardant and helps limit outgassing of potentially dangerous gases in the event the polymer does burn. These particles are added, less than 10% by volume, to the molten plastic.According to Lee, the nanoparticles are derived from montmorillonite, an environmentally friendly, naturally occurring clay found in huge deposits in Europe and the United States. Clay naturally exists in a platelet-like structure, a structure maintained by particles even on the nanoscale, and this platelet-like nature can impart a number of desirable qualities. But the clay structure must first be modified before it can be added to the polymer.Advanced Materials article, Lee explains: “In the natural state, [montmorillonite] platelets are held together by van der Waals forces and electrostatic forces to form crystallites (tactoids). Organic cationic surfactants, e.g., alkyl ammonium salts, are commonly used to modify the negatively charged clay surface through ion exchange, in order to improve wetting and lower the interfacial tension between the polymer and the clay that in turn enhances dispersion. Favorable interaction between the polymer matrix and clay surface and the resulting energy reduction are critical for the formation of exfoliated nanocomposites.”In the 16 October 2003 2, much the way impurities in a liquid or irregularities on the surface of a glass can trigger bubble formation. Reducing the pressure in the process that keeps the CO2 at a supercritical stage means the compound reverts to a gas, forming bubbles throughout the plastic. More nanoparticles within the molten plastic mean more bubbles will be formed throughout the plastic, and the large surface area of the nanoparticles provides much greater contact between the particles, the polymer matrix, and gases.Lee says one appealing aspect of clay as used in his work is that it forms a submicroscopic nucleation agent for the supercritical COClay, says Lee, is also an ideal strengthening agent because of its low cost. “Clay runs around two dollars per pound,” Lee says. “Other materials, like carbon nanofibers, would be even better, but a single-wall carbon nanotube can run five hundred dollars per gram.” Lee’s experiments have resulted in boards as strong as typical plastic foam, yet only two-thirds as thick. He’s experimenting with other strengthening materials, including aluminum and carbon.2 solubility, Lee explains. For example, poly-methyl methacrylate, used for optical fibers and as a shatterproof alternative to glass, has been a very good choice. Other good choices are polystyrene (used for applications including electric lawn and garden equipment and kitchen and bath accessories) and polyvinyl chloride (used for irrigation and other types of pipe). Polyolefins such as polyethylene  and polypropylene (used for flexible food packaging) are more difficult. Additionally, the process will work as well, if not better, with non–petroleum-based plastics. “Clay is hydrophilic,” Lee explains, “so it doesn’t like to mix with oil. A non–petroleum-based plastic would be much easier for us to mix in the clay.”Having thus far produced polystyrene and polymethyl methacrylate nanocomposite foams, Lee says his process can be used with any type of plastic, although certain polymers are more compatible. The process is better with polymers with high CONelson says test results to date may not fully support the flame retardant aspects of clay nanoparticles. The presence of these particles will definitely reduce peak rates of heat release, he says, but in other tests, they haven’t shown they provide much benefit.“Heat release is only one aspect of these industry tests,” Nelson says. “Does the material undergo sustained ignition? If so, then it’s not usable. . . . And the industry tests look at a broad range of things, like ignition, heat release, ease of extinguishment, and smoke and toxic gas formation.”Nelson also notes that tests have shown variable flammability depending on whether the clay-augmented sample is oriented vertically or horizontally. In horizontal tests, clay comes to the surface and creates a barrier, which stops degradation and heat transfer. But in vertical tests, the clay barriers break, exposing new melting plastic—but not before effectively hindering the flow of the plastic just long enough to make it burn faster. “I think, from what I’ve seen,” he says, “that nanoclays may be useful in combination with traditional flame retardants, thus lowering the volume of flame retardant you need to use.”Another concern, says Loh, is the concept of scalability. “The whole process of going from the lab to a commercial setting is always a challenge,” he says. “In the lab, you might be producing fifty grams of this stuff, while our pilot line might produce several hundreds pounds to a batch. The question is, how do you keep the same quality that you have in the lab? Labs use different equipment, and have different quality control aspects. The next stage for us in this project will be a pilot project, which we plan to have operational by year-end.”Scale-up is always a challenge, agrees Lee. “We are successful in one scale-up with one company, and while I don’t have other data points at this time, it should, in theory, work in other materials and processes,” he adds. “The critical issue is to have good mixing and pressure/temperature control.”Nelson thinks the issue comes down to application. He thinks it’s more likely that solid plastics will be replaced by better solids, and foams with better foams. He says, “Along with application comes the question of cost, which will always be the issue for industry. . . . What are the changes, what do they cost, and are they within reason? Also, you have to look at the qualities of the foam. Does it have the same initial properties? How does it age? These are the kinds of factors that industry will have to evaluate before adopting anything new.”2 are the answer for the plastic foam industry—but by 2010, at least, we should have an answer.Despite the questions still outstanding, momentum for that adoption appears to be building. Lee’s team recently received a $2 million award from the Ohio state government’s Wright Capital Project Fund to introduce novel nanocomposites to industrial manufacturers. Besides Owens Corning, his work has also attracted the interest of Procter & Gamble. Only time will tell whether clay nanoparticles and supercritical CO


While effective drug treatments have reduced the global disease burden, there remain important challenges to fighting and controlling the disease. Although leprosy is no longer a health problem in developed countries, it continues to affect millions of people in large parts of Asia, Africa, and Latin America. Effective chemotherapeutic treatments are available that have reduced the global disease burden dramatically, but there remain important challenges to fighting and controlling the disease.Mycobacterium leprae, the “Hansen's Bacillus” —may be affected by bacillary infiltration into the mucosa of the upper respiratory tract, bones, and testes . DiagnosThe social consequences for those affected with leprosy and for their families can be devastating.The disease occurs in a wide spectrum of forms, which stem from the varying host immune response to the pathogen. Individuals with tuberculoid leprosy display a strong cell-based immune response that controls bacterial proliferation and lesions, whereas patients with lepromatous leprosy lack specific cellular immunity, ending up with high mycobacterial loads and severe clinical manifestations. Most patients have borderline forms. After the age of puberty, leprosy has a male to female ratio of 1.5–2.0 to 1. Britton and Lockwood have pointed out that this male preponderance is real—it is not related to underdiagnosis in women, although in some countries it is accentuated by delayed presentation by female patients, which results in higher rates of deformity  than an epidemiological or program quality target,” says Feenstra. “For many, the indicator—the prevalence of patients registered for treatment—has become the goal in itself, and the actual goal—reduction of the leprosy transmission and incidence—has practically got out of sight”. Furthermore, the fixing of numerical targets may put excessive pressure on national leprosy programme managers, discouraging them from actively working to detect new cases, which in turn could jeopardise the country's elimination status.Another cause for serious concern is that the coalition that stands against leprosy is not as solid as it should be. In 1999, the Global Alliance for the Elimination of Leprosy (GAEL) was formed to inject new energy into the elimination campaign, bringing together WHO, the governments of the major endemic countries, the Japanese Nippon Foundation, the Novartis Foundation for Sustainable Development, the Danish Development Cooperation Agency (Danida), and the International Federation of Anti-Leprosy Associations (ILEP). Quite soon, major contrasts emerged between some of the GAEL partners, namely between WHO and ILEP, who always remained critical of the “elimination”-focussed strategy. The clash was so strong that ILEP was expelled from the alliance at the end of 2001.Later on, probably in response to the increasing pressure to achieve leprosy control, WHO invited an independent team of experts led by Richard Skolnik, former Director of the Center for Global Health at George Washington University , to evaluate the GAEL. The evaluation report, published in 2003, recommends that WHO should take leprosy activities beyond 2005, dropping the “elimination” goal in favour of “an explicitly broad-based approach to the control of leprosy, the avoidance of nerve damage, and the rehabilitation of those in need” . The teaThere are signs that this new alliance is emerging. “The process of dialogue and collaboration with WHO headquarters in Geneva has already been reestablished and is improving constantly,” says Sunil Deepak, president of ILEP and medical director of the Italian leprosy NGO Associazione Italiana Amici di Raoul Follerau (AIFO). Deepak adds, “We are very optimistic about further strengthening of this collaboration”. Feenstra confirms that stakeholders are exploring new ways of dialogue. “WHO is currently, in collaboration with its partners, ILEP, The Nippon Foundation and Novartis, developing a new strategy for the period 2006–2010 for sustaining quality leprosy control activities,” he says .John Porter from the London School of Hygiene and Tropical Medicine  recently argued that in order to make sure “the disease does not go underground”, the “elimination” strategy must be swiftly converted to a “post-elimination” strategy . As recoWork to dispel the stigma of leprosy and to introduce patients back into their communities must also be strengthened, experts note, in order to end social discrimination toward people with leprosy . LeprosyMycobacterium bovis with the eventual addition of heat-killed M. leprae, has been proven to offer some immunity to leprosy. Its reported efficacy ranges from 34% to 80% in different countries [Lockwood and Suneetha have also suggested that the routine use of vaccination could benefit the outcome of WHO's anti-leprosy strategy . Althougountries . Despiteountries . Anotherountries .M. leprae—perhaps even in the soil in endemic regions.” Healthy human carriers also do exist, says Donoghue, who points out that by using sensitive molecular methods it is possible to detect the DNA from M. leprae in people who showed non-specific skin lesions and who had not been thought to have leprosy. Even after a ten-year MDT programme, more than 5% of healthy individuals in a leprosy-endemic area were positive for M. leprae DNA in their nasal passages, a recent study found, suggesting a high level of environmental contamination [Finally, important research issues remain to be addressed. They include developing improved diagnostic tests and better ways to monitor and treat nerve damage, and understanding why MDT has not interrupted transmission . “We shamination . “BeforeIt is widely believed that the leprosy elimination campaign has been a positive one. A comparably large consensus must now come together around the post-2005 leprosy agenda, to make sure that we do not lose the gains achieved to date or miss this unique opportunity to reach complete control of leprosy. Political, medical, or scientific disputes may have previously impeded unity among WHO and other stakeholders, but a reinforced partnership is now needed to continue the struggle to control and eradicate the disease.


Critical to our many daily choices between larger delayed rewards, and smaller more immediate rewards, are the shape and the steepness of the function that discounts rewards with time. Although research in artificial intelligence favors exponential discounting in uncertain environments, studies with humans and animals have consistently shown hyperbolic discounting. We investigated how humans perform in a reward decision task with temporal constraints, in which each choice affects the time remaining for later trials, and in which the delays vary at each trial. We demonstrated that most of our subjects adopted exponential discounting in this experiment. Further, we confirmed analytically that exponential discounting, with a decay rate comparable to that used by our subjects, maximized the total reward gain in our task. Our results suggest that the particular shape and steepness of temporal discounting is determined by the task that the subject is facing, and question the notion of hyperbolic reward discounting as a universal principle. When we make a choice between two options, we compare the values of their outcomes and select the option with a larger value. However, what if one option leads to a larger delayed reward and the other leads to a smaller more immediate reward? Naturally, we assign a larger value for a larger reward, but it is “discounted” if the reward is to be delivered later. Thus, the value is a monotonically decreasing function of the delays. Previous behavioral studies have repeatedly demonstrated that humans and animals discount delayed rewards hyperbolically. This has practical importance, as hyperbolic discounting can sometimes lead to “irrational” preference reversal: for instance, an individual may prefer two apples in 51 days to one apple in 50 days, but if the days come closer, he prefers one apple today to two apples tomorrow. On the contrary, exponential discounting is always “rational,” as it predicts constant preference. Here, in a new task that mimics animal foraging, and that uses delayed monetary rewards, Schweighofer and colleagues showed that humans can also discount reward exponentially. Furthermore, it is remarkable that by adopting exponential discounting, their subjects maximized their total gain. Thus, depending on the task at hand, the authors' study suggests that humans can flexibly choose the type of reward discounting, and can exhibit rational behavior that maximizes long-term gains. Because of constant decay rate, exponential discounting is “rational,” as it predicts constant preference.In exponential discounting, the reward value Typical human studies are questionnaire-based: subjects are asked to make a number of choices between small immediate rewards and larger rewards weeks, months, or years in the future, after thinking about the consequences of each alternative  (but see(ITI), if the animal consistently makes a choice that gives the same reward R after the same delay D, the average reward rate is the hyperbolic function of the delay  consists of two terms.α, β, η, and μ are the lower and upper bounds of the LD,SD space. SimilarlyTo find the parameters V with respect to the parameters,a and b:We then computed the partial derivative of a and b that maximized the expected reward rate V. We computed the maximum of V using the Matlab function fminunc, which is similar to the function fmincon, but without any constraints on the parameters.We used an optimization method (1) to verify our analytical results and (2) to perform a sensitivity analysis to examine how variations in experimental parameters affected the values of


In a world whose population exceeds 6.5 billion, declining human fertility might not seem to be a critical problem. After all, overpopulation has been a global concern for decades. Declining fertility rates in more advanced nations largely reflect the changing role of women and their rapidly growing presence in the workplace—fertility declines may stem at least in part from the modern tendency to delay child-bearing until later in life, when fertility naturally declines. But this doesn’t explain the fact that, according to a December 2005 report of the CDC’s National Survey on Family Growth (NSFG), the fastest-growing segment of U.S. women with impaired fecundity (the capacity to conceive and carry a child to term) is those under 25. The rising incidence of fertility-impairing health factors such as obesity also likely plays an important role. Clues from environmental exposure assessments, wildlife studies, and animal and human studies hint at additional factors: exposure to low-level environmental contaminants such as phthalates, polychlorinated biphenyls (PCBs), dioxins, pesticides, and other chemicals may be subtly undermining our ability to reproduce.As recognized by the American Society of Reproductive Medicine, infertility is a biological disease that impairs a couple’s ability to achieve a viable pregnancy. It can be caused by hormonal, ovarian, uterine, urological, and other medical factors. Known risk factors include advanced age, being over-or underweight, lack of exercise, smoking, alcohol and substance abuse, sexually transmitted diseases, and poor nutrition.According to the American Society of Reproductive Medicine, a medical infertility cause can be identified, or perhaps only indefinitely suggested, in approximately 90% of cases and may be multifactorial in 25% of cases. Male factors include low sperm count and sperm abnormalities, such as altered morphology and low motility. Female factors stem from ovulation problems such as premature ovarian failure (early menopause), thyroid irregularities, polycystic ovarian syndrome, and fallopian tube obstruction.Up to 10% of infertility cannot be explained medically. Fertility transcends the reproductive system, notes Louis Guillette, a professor of zoology at the University of Florida in Gainesville. “When you talk about infertility, you literally are talking about probably almost every system in the body—infertility is an integrated signal of all these different systems,” he explains. “Trying to tease out which system, or more than likely what multiple systems have been altered, leading to that phenomenon, is very tough work.”Current Practices and Controversies in Assisted Reproduction, at least 80 million people worldwide are estimated to be affected by infertility. Infertility rates range from less than 5% to greater than 30% depending on location and how infertility is defined, with higher rates associated with lack of medical care access. Based on the 2005 NSFG report, approximately 12% of American couples experienced impaired fecundity in 2002. This is a 20% increase from the 6.1 million couples who reported an inability to have children in 1995.Infertility is generally defined as occurring when a couple cannot become pregnant after trying to conceive for at least one year (or six months if the woman is over age 35). According to the 2001 WHO report Fertility and Sterility, David Guzick and Shanna Swan of the University of Rochester School of Medicine and Dentistry noted that “impaired fecundity” as defined by the NSFG implies a decrease in fertility, but the same study also showed that fertility, defined there as a married woman unable to become pregnant within 12 months, has increased.Determining whether infertility is actually increasing is more complicated than these numbers imply, however. In a paper published in the September 2006 issue of in utero.”The absence of definitive information can frustrate couples experiencing fertility problems as well as experts. “There seems to be more to it than can be explained from traditional understanding about impacts,” says Joseph Isaacs, president and CEO of RESOLVE: The National Infertility Association. “As a patient advocacy group, we believe more research into environmental impacts is needed. We fear that future generations may be at risk because of exposures to toxic substances as early as A person’s reproductive potential begins shortly after his or her own conception. Based on the embryo’s chromosomal inheritance, hormonal signals are created to direct the structure and function of the reproductive tract. Normal development depends upon a correct balance of androgen and estrogen signals being delivered at appropriate times.Fetal development can be altered by external factors as demonstrated by the human experience with the synthetic estrogen diethylstilbestrol (DES), prescribed to prevent miscarriage between 1947 and 1971. The drug didn’t affect mothers, and it didn’t lower miscarriage incidence; in fact, it significantly increased it. It also induced changes in the developing reproductive tract of female offspring.New England Journal of Medicine, it was reported that daughters with prenatal DES exposure had significantly increased incidence of vaginal cancer, which is normally quite rare and was virtually unknown in young women prior to DES. Later research revealed structural abnormalities of these women’s reproductive tracts and effects in their male offspring including increased risk of cryptorchidism (undescended testes) and low sperm counts.In the 15 April 1971 issue of the British Medical Journal indicating significant declines in sperm counts in many countries between 1938 and 1990. The findings were controversial because the reviewed studies used inconsistent designs and methods. In October 1997, however, a review published in EHP by Swan and others confirmed the findings for males in the United States and indicated an even sharper decline among European men. Other studies have found declines for specific areas or no decline at all.The study of endocrine disruptors has raised concerns about the reproductive effects of exposure to certain environmental compounds that affect the endocrine system via estrogenic, androgenic, antiandrogenic, and antithyroid mechanisms. One key report was a 12 September 1992 review in the “I think the evidence across studies is mixed,” says Russ Hauser, an associate professor of environmental and occupational epidemiology at Harvard School of Public Health. “Historical studies were not designed to explore this question. It wasn’t that someone set out forty or fifty years ago to design a study to look at how semen quality is going to change over time.” There are going to be limitations in the data because of that, he explains, so it’s hard to determine whether there is a true temporal trend. “However,” he adds, “the data suggest there are definite geographical differences between countries and regions within countries in semen quality.”International Journal of Andrology, comparisons of sperm quality among populations of European men have revealed that as many as 30% of young Danish men have low sperm count, and an additional 10% may be infertile. Denmark also has an unusually high rate of testicular cancer. Rates have been increasing in many countries over the last 50 years, but the Danish rate is noticeably higher; for example, four to five times higher than the Finnish rate.According to Niels Skakkebæk of Rigshospitalet in Copenhagen and colleagues writing in the February 2006 issue of the Human Reproduction, an overarching disorder, testicular dysgenesis syndrome (TDS), in which perturbation of testis development in fetal life sets the stage for hypospadias, cryptorchidism, testicular cancer, and reduced sperm quality.This difference prompted researchers to also examine incidence of hypospadias  and cryptorchidism. Not only did both disorders occur more frequently in Danish boys compared with Finnish boys, but the Danish rates had risen in recent decades. These findings as a whole inspired Skakkebæk and colleagues to propose, in the May 2001 issue of It’s reasonable to suspect there might be a female corollary to TDS. “We have no really good reasons not to expect that women are as sensitive to environmental chemicals as the males are,” says Jens Peter Bonde, a professor of occupational medicine at Århus University Hospital in Copenhagen. He points out that it’s easier to study male fertility because men can easily provide sperm samples. “That’s one basic reason that there has been so much attention on the males, but from a biological point of view one would definitely expect that the female reproductive system might be vulnerable also,” says Bonde.According to Guillette, another stumbling block is the accepted, but unproven, dogma that an embryo will develop as a normal female barring any hormonal signals to become male. “It hasn’t been an area where there have been substantial amounts of work done. There’s certainly very good work, but not the same kind of huge body of literature that one sees about the developing testis and the male reproductive system,” he says.EHP. Their results suggested a subtle change in boys’ development—a shortening of the anogenital index —associated with prenatal exposure to several phthalates. This finding is not a predictor of future fertility and needs confirmation, but it is noteworthy as the first study to link verified prenatal exposure to a specific outcome.One of the few epidemiologic studies to link low-level human exposure to an environmental contaminant with a specific end point was Swan and colleagues’ investigation of prenatal phthalate exposure, published in the August 2005 issue of Consequences of disrupting the normal hormone milieu have also been observed in wildlife. Examining alligators in polluted lakes in northern Florida, Guillette’s group has observed altered function of the ovaries and testes, smaller penis size, and abnormalities that extend to the thyroid gland, liver, and immune system. A robust body of literature details reproductive effects in fish, amphibians, and reptiles related to their exposure to endocrine disruptors. Evidence of these effects has also been seen in wild mammals such as polar bears and seals. Laboratory animal experiments have confirmed these wildlife findings, demonstrating that effects are not necessarily from steroid receptor disruption, however, but may, for example, be observed in altered synthesis and control of endogenous hormones.The study of fertility also encompasses pregnancy, especially the early weeks following fertilization. Early pregnancy loss is normally quite high in humans, with an estimated 30% of pregnancies ending in miscarriage in the first six weeks. A frequent cause of miscarriage is aneuploidy, an incorrect number of chromosomes in the embryo, and mouse studies have shed some light on potential environmental contributors to this condition.Current Biology, the researchers replicated exposure experimentally and found that BPA derailed proper chromosome segregation during oocyte meiosis.During a 1998 investigation of age-related aneuploidy rate increases, Patricia Hunt, a professor of molecular biosciences and a reproductive biologist at Washington State University, and her colleagues were amazed to see a sudden rate spike in their mouse colony. An investigation revealed correlation between damage to the plastic mouse cages and the chromosomal abnormality. Further scrutiny implicated bisphenol A (BPA), a suspected environmental estrogen used in plastics manufacture, as the potential causal agent. In a study published in the 1 April 2003 issue of An extension of this research has been completed with amazing—but not yet published—results, and Hunt hopes that the line of inquiry can be extended to humans. “One of the things that my new research on BPA has made me wonder is whether or not there could be environmental effects that would change the frequency or in specific populations might cause noticeable differences in aneuploidy,” she says.Hunt says it’s hard to know precise numbers of human aneuploidy cases. “We can’t see the loss that occurs preimplantation, but we make an assumption that there’s quite a bit, based on what we can see and what we think must happen,” she says. But whether there’s been an increase in aneuploidy over time cannot be known. “Human aneuploidy studies were done mostly in the 1970s and early 1980s,” says Hunt. “Is this aneuploidy rate the same across all populations? To the best of our knowledge, it has been, at least in those previous studies. But is the rate the same as it was then? We wouldn’t know. We wouldn’t be able to see a dramatic increase in chromosomally abnormal spontaneous abortions, because those kinds of studies aren’t currently under way.”Extending animal studies to human health is a challenge, though. Genetically, the reproductive system is highly conserved across species, making it likely that responses to inputs would be similar. But species differences in exposure, metabolism, and anatomy preclude making a direct comparison.“Wildlife studies cannot be related to humans one to one,” says Guillette. “If one’s looking at the functioning of the ovary, or the functioning of the brain, and hormones, and even the genes that seem to be involved with the proliferation or the growth of the uterus or the development of an egg, for example, they’re incredibly conserved.” He explains that if problems are seen in these animals at a certain level, and researchers are able to identify mechanisms that are being disturbed leading to those abnormalities, then that raises possible concerns for humans, even if humans are exposed in a slightly different manner.Seminars in Reproductive Medicine. For example, in the first phase of the EPA-funded Study for Future Families, of which Swan is the principal investigator, she and her colleagues saw significant reductions in sperm concentration, motility, and total motile sperm in men from Columbia, Missouri, compared with men in New York City, Minneapolis, and Los Angeles. In an in-depth follow-up study comparing variables between the Columbia and Minneapolis men, the researcher discovered that the Missouri group had had higher exposure to agricultural pesticides. Further, men with low sperm counts were more likely to have higher urine metabolite levels of the pesticides alachlor, atrazine, metolachlor, and diazinon.Geographic differences may suggest environmental exposures that need investigation, wrote Swan in a paper published in the February 2006 issue of Another geographically based study, INUENDO, investigates risks to human fertility from persistent environmental organochlorines. The European Commission project centers on Arctic populations including Swedish fishermen and the Inuit of North America and Greenland, whose exposure to persistent organic pollutants such as PCBs and DDT metabolites are among the highest in the world. “There are many indications from animal studies and from wildlife studies, but very few indications from human studies telling us whether we have a problem or not,” says Bonde, who serves as coordinator of INUENDO.Human Reproduction suggested a longer time to pregnancy related to serum concentrations of PCB and DDE in mothers and fathers. Additional results published in the May 2006 EHP suggested an altered sex ratio of offspring (fewer boys than would otherwise be expected) related to PCB and DDE exposures.“The basic idea [behind INUENDO] was to go to places in the world where we know that people have high level of exposures to substances that are suspected to cause these effects in fertility,” says Bonde. “That’s the reason we went to Greenland and to Sweden, where fishermen are known to have very high exposure levels; we have other populations that have lower levels of exposures, so we have contrasts of exposure.” Results published in March 2006 in EHP, Hauser’s group described evidence suggesting a relationship between PCBs and phthalates and human sperm motility, possibly due to PCBs’ inhibiting a key enzyme in phthalate metabolism.Exploring multicompound exposures is yet another challenge in environmental epidemiology. “Individuals are exposed to many different phthalates, a variety of persistent and nonpersistent pesticides, different patterns of PCB congeners, as well as other chemicals,” says Hauser. “How do we take all that information, based on the chemical assessment in urine or in blood, and use that to assign exposure for that individual to ten, or twelve, or many more different compounds?” he says. In the April 2006 issue of Hox genes that direct uterine development. The researchers initially focused on DES effects and discovered that the compound alters expression of the Hoxa10 gene in mice, affecting the tissue type that grows in the uterus, cervix, and vagina. Effects were triggered only with exposure during development, but not during adulthood, and later experiments revealed that the pesticide methoxychlor had similar effects.Genes themselves offer another platform for investigation. Hugh Taylor, director of the Yale Center for Research in Reproductive Biology, leads a team investigating the role of estrogen-regulated “The important thing is that these agents really seem to imprint the expression pattern, even long after the agent is removed or there’s no longer an exposure,” says Taylor. “When we have a clear-cut animal model and know the genes that are affected, we can start to think about evaluating that exposure by looking for changes in the gene expression earlier and see if it has a significant effect rather than waiting a whole generation.”This is a goal of research in epigenetics, the study of how genetic messages may be edited through methylation or other means without changing the actual DNA sequence. For example, Rebecca Sokol and colleagues at the University of Southern California are currently investigating whether DNA methylation in sperm might serve as a bio-marker of environmental exposure and a means of assessing male fertility. Additionally, preliminary work at Washington State University and at the NIEHS indicates that an epigenetic event in one generation can “reprogram” the germline and affect later generations. In essence, the exposures of one’s great-grandparents could still matter today.Previous generations’ exposures would be useful information to have, according to Hunt. “What we really need is data on generations ago, and we simply don’t have that data,” she says. “We have to wait a generation to see. We have to wait until . . . young exposed males grow up to the point where we can assess sperm counts.”This will require prospective studies to determine early exposures. “If you want to look at fertility—and it’s difficult to do—you ideally would want to do a study in which you start assessing environmental exposures preconception,” says Hauser. “You’d have to identify couples who are thinking of trying to conceive and try to understand their environmental exposures, and then follow them forward in time.”According to Alison Carlson, a senior fellow at The Collaborative on Health and the Environment (CHE) in Bolinas, California, another need is very basic: tracking the incidences of infertility and common known causes. “For us to try to make headway studying environmental influences on fertility, it’s really hard when we don’t have good baseline data,” she says. “We don’t know the real incidence and prevalence rates of premature ovarian failure and polycystic ovarian syndrome and lots of other end points that people study. We don’t know what they are, so how can we study trends and the environmental contributions?” she asks.A thorough exploration of environmental effects on fertility will require the expertise of demographers, epidemiologists, clinicians, biologists, wildlife researchers, geneticists, molecular biologists, exposure assessment specialists, toxicologists, and others—and discussion requires someone “to set the table,” says Carlson. A February 2005 workshop titled “Understanding Environmental Contaminants and Human Fertility Compromise: Science and Strategy” demonstrated multidisciplinary fervor for investigation, and a more in-depth conference, the “Summit on Environmental Challenges to Reproductive Health and Fertility,” cosponsored by CHE and the University of California, San Francisco, is scheduled for 28–30 January 2007. “Reproduction is such a human, deep-seated, deeply psychically coded thing,” says Carlson. “It’s hard not to care about fertility compromise.”


The average Earthbound American, estimates the U.S. Environmental Protection Agency (EPA) uses nearly 24 gallons of water daily for personal uses such as drinking, toilet flushing, hygiene, and cleaning. International Space Station (ISS) crew members, on the other hand, are limited to little more than half a gallon per day. Yet, with that little bit of water weighing about 5 pounds, and the cost of lifting something into low Earth orbit can top $10,000 per pound, it would make far better economic sense to provide astronauts with water on-site.Aerospace engineers are busy working on a modern-day form of alchemy, finding new ways to find water in space without having to lug it along from Earth. And while many of the technologies are being developed with an eye toward the stars, certain aspects may be suitable for use here at home on planet Earth.Every time an astronaut exhales, washes up, or urinates, water is involved. In an effort to minimize the amount of fluid lifted into orbit, the National Aeronautics and Space Administration (NASA) is seeking ways to recapture that water, clean it, and store it for reuse.The ISS currently provides clean water through the use of a water recovery system that reclaims wastewater such as used oral hygiene water, urine, and cabin humidity condensate. But the space environment offers unique challenges to the provision of water. For example, water must contain no dissolved gases, as gas doesn’t separate well at zero gravity, either in tanks or in the body. Therefore, the water must be purified to a level exceeding Environmental Protection Agency standards for Earth drinking water. The WRS consists of a urine processor assembly  and a water processor assembly developed by researchers at NASA’s Marshall Space Flight Center and Hamilton Sundstrand Space Systems International.According to Dave Parker, program manager for Hamilton Sundstrand’s water processor program, the water processor assembly is a multistage system that uses filters to remove particulate matter and salts. The water is then run through a catalytic oxidizer to remove low-molecular-weight organic molecules such as alcohols. This part of the process takes place at a temperature of 275°F, and under pressure so it doesn’t flash to steam, Parker explains. The system then removes any byproducts and remaining dissolved gasses, and next goes through an ion exchange process to remove the oxidation products.This process, according to Parker, can produce about 1.5 gallons of treated water per hour, and uses approximately 700 watts of power. To reduce maintenance times and the volume of consumables that must be delivered from Earth, the system has been designed with an 80- to 90-day change-out schedule for particulate filters, and a 60- to 70-day schedule for chemical filters, with no more than 12 hours of maintenance time required per year.The water processor assembly is designed to provide limited amounts of highly purified water with minimal energy consumption and maintenance, but Parker believes the system could be scaled up for Earth usage. “We’re producing as nearly pure potable water as you’re likely to find anywhere,” he says. “The question you’d have to answer on Earth is whether you need water of that purity.” Parker suggests the system could be used in military applications, to protect crews against chemical or biological attack, or aboard naval vessels. It could also work in hospitals, where high-quality water is important. “We’re also working with the Army to design a system to create potable water from diesel exhaust,” he says.There are also substances often encountered in terrestrial water that you’ll never find aboard the space station, such as arsenic, mercury, and heavy metals, but Parker says the water processor assembly could be adjusted to deal with these substances in a limited-application water stream. “While you could plug this system into a municipal water system, I suspect that the economics wouldn’t work. The system operates to higher standards, and avoids things that municipalities traditionally employ, such as the addition of chlorine to sterilize water. NASA doesn’t allow any chlorine aboard the ISS, so we use heat instead. That wouldn’t be economical in a multimillion-gallon-throughput municipal system.”With NASA looking in more detail at a manned Mars mission—which would involve 40 million miles and 3–5 years—work has begun on a fully regenerative water recycling system, one that can provide a crew with adequate water for drinking and hygienic needs for up to three years without recharging. Enter the Vapor Phase Catalytic Ammonia Removal (VPCAR) system.Michael Flynn, the project’s principal investigator at NASA’s Ames Research Center, says VPCAR has been designed to mimic the natural hydrologic cycle. “On Earth, you open the tap, drink water, produce waste, treat the waste, and discharge it back into the ocean,” he explains. “The sun heats the water, which evaporates and forms clouds. Those clouds are exposed to ultraviolet radiation, which destroys organic contaminants, and then rain falls to begin the cycle again. We’ve integrated all of these processes into a single small machine. We take in waste water, vaporize it, oxidize organic contaminants, re-condense it, and the water is ready for use.”In general, says Flynn, nonregenerative technologies (like the water processor assembly), are dominated by adsorptive technologies such as activated carbon, which boast low power consumption. “You make the trade-off of having a shuttle fly up every ninety days to resupply expendables like filters because the system uses relatively little power,” he says. On the other hand, there will be no resupply opportunity on a manned Mars mission, so it’s desirable to spend more on power than on resupply. For example, Flynn says, the nonregenerative systems aboard the ISS only use an estimated 123 watt hours/kg, compared to what he says is around 300 watt hours/kg for the fully regenerative VPCAR.VPCAR works by sending the waste stream across a wiped-film rotating disk evaporator, which removes inorganic salts and nonvolatile large-molecular-weight organic contaminants. Lightweight organic molecules and ammonia, which are volatilized in the evaporator, are oxidized by a high-temperature catalytic oxidation reactor, converting these organics into carbon dioxide, water, and nitrous oxide. This high-temperature process also helps destroy any biologically active organisms in the waste stream.Full characterization studies of VPCAR have been completed, and the system, Flynn says, meets all NASA specifications. The next step will be a test aboard training aircraft, followed by full-scale flight-testing during a proposed lunar mission.VPCAR, Flynn admits, would have limited applications on Earth, although some aspects of it are being considered, including the evaporative portion of the system, which has been examined by the U.S. South Pole research station, which wants to purify its sewage such that it could be used to make an ice layer for the research station’s runway. “We also have some rural Alaskan tanneries looking at using the system to recycle their waste, and some oil companies are looking at it as a technology to separate oil and water,” Flynn says. “VPCAR is also being looked at as an alternative method of distilling salt water into fresh.”While some researchers are trying to make sure there are no bacteria in the water, others are going out of their way to welcome them. Tony Rector is a bioprocess engineer with Dynamac Corporation at Kennedy Space Center, where he and colleagues are working on a project called ARMS—the Aerobic Rotational Membrane System.ARMS consists of a clear Plexiglas reactor vessel, filled with 115 tubes (dubbed “membranes”) that are home to a community of bacteria. Oxygen moves from the inside of each membrane to its outside surface, where bacteria are present in colonies called biofilms. Contaminated water flows past these biofilms, where the bacteria can use the oxygen to transform undesirable compounds found in the wastewater to less harmful compounds. Biological treatment reactors using membranes aren’t new technology, but this system is innovative in that the membranes rotate, exposing more of the bacteria to more of the infused oxygen and the contaminants that provide their nourishment.“Biological systems like these can achieve high treatment efficiencies with low mass and energy requirements,” says Rector. “By rotating the membranes, we can enhance mass transfer, making the system as efficient as possible.”As living organisms, bacteria are subject to many of the same stresses that will impact human astronauts, and if the bio-community goes down due to some shock  it can be days before the community can be resuscitated. “Part of our long-term plan is to subject these organisms to a variety of shocks, and see how they react and recover from such events,” says Rector. “We’d also like more information on their ideal living conditions, what bacterial species are most tolerant and resilient, and other information of that sort.” Rector’s research group will also be examining different biochemical processes in a variety of bacterial species, including nitrification bacteria and hydrogen-oxidizing bacteria. Potential candidate bacteria will have to be evaluated for their tolerance for pharmaceuticals, hormones, antibiotics, and other substances that may be excreted by the astronauts using the system.Because of the potential sensitivity of the living organisms, and because bacteria are unable to process all of the materials in a typical waste stream, Rector envisions using ARMS as a first phase in an overall water treatment process in space, followed by a chemical/mechanical process. “Our goal is to reduce the contaminant loading on these processes and therefore reduce the size and energy requirements for larger-scale physical and chemical systems,” Rector says.“Bioregenerative research, focusing on water recovery, has been conducted at NASA research centers for many years. While we are in the initial stages of the ARMS project, we are very encouraged by its current performance,” says Rector. “Depending on mission scenarios and timelines, it could be five or six years before we can complete our investigation of the biological and mechanical component aspects of this system. I think there’s a lot of potential, but there’s still a lot of research to be done.”ARMS, he says, could well find maritime applications, perhaps aboard cruise ships, which must thoroughly treat their waste before discharge. “This system will find its best use in a small environment,” he says.“Best use in a small environment” seems to be a key descriptor of all of these processes. None of the individuals involved in research on the three systems envisions them as replacements for large-scale municipal water treatment facilities, but all agree they should work—and work well—in a confined environment, where it’s necessary to have very clean water, and all that’s available as feedstock is what Flynn describes as “the nastiest stuff imaginable.” The military, medical facilities, any place with a need for high-quality water supplies where conventional sources are unreliable—all are potential down-to-Earth targets for NASA’s spaceborne water systems.