While other studies have shown a relationship, her findings did not. A laboratory working on contract performed chemical analyses on the other half of the egg collection. OCs are pesticides. PCBs are compounds found in electric transformers, some plastics, lubricants and flame retardants. And dioxins most often are associated with pulp and paper mill chlorine bleaching processes and trash burning.
Dioxins are the most toxic of the substances the labs searched for.
Scientists' concern over these compounds goes beyond mere presence to something called biomagnification. Although organochlorines, like the pesticide DDT, a derivative DDE, and PCBs have been banned since the early 1970s, years of use have left residues in river sediments and in the food chain. These toxins are absorbed and stored in the fat tissue of fish and birds and pass the poison along up the food chain. With each link the load gets bigger. What starts out as a trace in a fish can reach dangerous levels in fish-eating birds like herons and eagles at the top of the food chain.