Behavioral Sexual Dimorphism in School-Age Children and Early Developmental Exposure to Dioxins and PCBs: A Follow-Up Study of the Duisburg Cohort.
Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), also referred to as dioxins, and polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs). Because of their accumulation in the food chain and their possible toxicity at even environmental background concentrations, they are still of environmental concern, although exposures have markedly decreased in the general population (Wittsiepe et al. 2000). Dioxins and PCBs are mixtures of congeners that differ in the number and the position of chlorine atoms on the two ring systems. Depending on the degree of chlorination, their biological half-life varies from days to years (Ogura 2004). PCDD/Fs are by-products of combustion processes. PCBs were synthesized and used as synthetic oils in many diverse industrial applications from 1929 until their production and further use was discontinued in the late 1970s.