Human Exposure To Halogenated Aromatic Compounds

Environmental Health Sciences

Investigators

Linked publications & trials

Abstract

Aims: PCBs and similar compounds are a worldwide pollution problem, and appear with high prevalence in human tissue. For many years we have been studying the consequences for child development of exposure to these compounds, at obviously toxic levels in a food poisoning incident in Taiwan, at relatively high agricultural exposures in rural Mexico, and at background levels in the US. This year, only the Yucheng, or oil disease, study of poisoned persons from Taiwan produced new analyses, although we have used the data from the Mexico study to inform the new, worldwide debate on the use of DDT to combat the resurgence of malaria. Procedures and techniques: In a separate study, we examined and then followed children who were born to mothers poisoned by PCBs and the highly toxic polychlorinated dibenzofurans in the 1979 "Yucheng" incident. We have also followed the adults. We hypothesized that, in 1995, the children would continue to be affected by their prenatal exposure to PCBs/PCDFs as they were in 1991-1992. We hypothesized that the adults would report higher rates of problems known to be associated with PCBs, like acne, but we also hypothesized that the women would report increased menstrual flow and perhaps dyspareunia, because of the primate model of dioxin toxicity showing endometriosis from long term, low level exposure. Accomplishments: In Taiwan, we have been following about 117 children who had transplacental exposure to high doses of PCBs and related compounds. Beginning in 1985, we have documented that the children who were born between 1979 when the poisoning occurred and 1985 have ectodermal defects, developmental delay, and a behavior disorder. This year, for the first time, we were able to show that, by 1995, the reported behavioral abnormalities in the children were diminishing, although their developmental delay remained fixed. This has implications for the study of how PCBs affect the brain, since in previous data the cognitive and behavioral abnormalities occurred together, making it difficult to tell whether they occurred through the same or different mechanisms. A paper describing this work is submitted. We did a survey of the general health of the adults who were poisoned in Taiwan, some of whom were the mothers of the children we have been studying. Since these compounds are very toxic to the female reproductive system when studied in monkeys, we were very interested to find the mild disturbance of menstrual function seen among the older women, with only minor differences in menstrual flow reported, and no change in reported dysmennorhea, fertility, family size, or libido. Those who advocate the use of DDT for malaria control claim that little or no morbidity results from its use. We claim that shortened duration of lactation, which we have observed in association with DDE exposure in North Carolina and Mexico, might result in increased infant mortality in the same regions where it would be most logical to spray for malaria, since poverty and infection rates are high there. The question of how best to control malaria and how to study the consequences of the tactics used will be an active area for the next several years, since 25 countries have gotten exemption s from the world wide ban on DDT to use it to kill mosquitoes.