Time Trends in Human Milk Derived from WHO- and UNEP-Coordinated Exposure Studies, Chapter 1: Polychlorinated Biphenyls, Polychlorinated Dibenzo-p-Dioxins and Polychlorinated Dibenzofurans

Abstract

AbstractTemporal trends of polychlorinated biphenyls (PCB), polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in human milk were assessed by consideration only of countries with repeated participation in WHO/UNEP-coordinated exposure studies performed between 1987 and 2019. In contrast to a general estimation of time trends from all participating countries, this is a more precise approach because levels among countries are often highly variable. Studies on time trends for contaminants in human milk are important components of the effectiveness evaluation of the Stockholm Convention on Persistent Organic Pollutants (POPs). There is no stipulation of a quantitative goal for the rate of reduction/decrease in POPs levels, however, as a quantitative objective for studies, these should have the ability to detect a 50% decrease in the levels of POPs within a 10-year period.For non-dioxin-like PCB (calculated as the sum of six indicator PCB), a decrease of about 50% to 60% over 10 years was achieved in most of the five UN Regional Groups. Considerable decreases in concentrations with reductions of up to 95% over three decades were observed in European countries with high concentrations at the end of the 1980s, compared to slower decreases in less polluted ones. For the toxic equivalents (TEQ) of PCDD/PCDF and the total TEQ of PCDD/PCDF and dioxin-like PCB, a decrease of about 50% over 10 years was found mainly in Western European and some other countries with initially relatively high concentrations. TEQ concentrations of PCDD/PCDF decreased by up to 90% over three decades. Lower decreases observed in many countries have to be seen in the context of the quite low levels in these countries in comparison with other countries.