A general population from Thailand: incidence of common allergens with emphasis on XXXX .

@entity1 @entity566 @entity7227 @entity484 @entity10155
BACKGROUND: Most studies on the prevalence of @entity566 to the permanent hair dye chemical @entity7227 ( @entity10155 ) are reported from populations of @entity484 @entity1 attending patch-test clinics, and are assumed to be much higher than in the normal population. No data exist on incidence of senitization to PPD resulting from the use of commercial hair dye preparations over a defined time period. METHOD: A total of 2545 healthy adult volunteers (Bangkok) were screened for @entity566 through standard patch testing. Volunteers not allergic to PPD were then recruited into two groups: one group applying a commercial hair dye brand as instructed on a monthly basis for 6 months (n=548) and the other group (controls) (n=516) was instructed not to dye their hair for 6 months. Sensitization to PPD resulting from the use of hair dye over this period was then detected by repeat patch testing. RESULTS: The prevalence of @entity566 in a normal adult population was 2.7% (m=2.4%, f=3.2%). Projected to the adult Thai population, at least 1,000,000 Thai individuals could be allergic to PPD. The incidence of sensitization through the monthly application of standard commercial hair dye preparations over a 6-month period was 1.3%, substantially higher than in controls (0.4%), although numbers were small and not statistically significant. INTERPRETATION: There is a higher prevalence of hair dye @entity566 among the normal population than previously thought. The incidence of new cases of @entity566 would indicate that current regulations and practice of hair dye exposure lead to PPD sensitization and @entity566 , which is a public health problem.
