Foodborne Chemicals: Polychlorinated Biphenyls and Dioxins^7,8

PCBs are synthetic organic chemicals that were used in many products before 1977. Over 1.5 billion pounds were produced in the United States. They now represent an environmental contaminant concentrated in fatty fish and other animal products (dairy products, eggs, and meats), and are also detectable in human tissues.

Evidence strongly suggests that PCBs are human carcinogens and adversely affect the immune, reproductive, nervous, and endocrine systems of animals and humans. PCBs can cross the placenta and may contribute to cognitive problems in children.⁹ PCBs also enter breast milk, although the contribution of this route of exposure to health effects in infants is not well established.¹⁰

Dioxins are usually byproducts of industrial processes, including incineration, although they also result from volcanic eruptions. Like PCBs, they are found mostly in animal products near the top of the food chain, and ultimately can affect animal and human immune, reproductive, nervous, and endocrine systems. Although less than 10% of dioxins are considered significantly toxic, their long half–life–about 7 years in the human body–makes them an important public health concern. Destroying dioxins requires incineration at temperatures above 850o to 1000o centigrade.¹¹