Foodborne Chemicals: PCBs, Dioxins, and Pesticides

Polychlorinated Biphenyls (PCBs) and Dioxins

• PCBs are synthetic 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 toxin that can be found 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 carcinogens and can damage the immune system, reproductive organs, the brain, and hormones. PCBs can cross the placenta and may contribute to mental problems in children. PCBs also enter breast milk, although it is not yet established if this contributes to poor health in infants.
• 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 the immune system, reproductive organs, the brain, and hormones. Although less than 10 percent of dioxins are considered significantly toxic, they can remain in the human body for decades–making them an important public health concern.

Pesticides

More than 4 billion pounds of pesticides (including herbicides) are used annually in the United States. The prevention of unnecessary and accidental exposure through direct contact, or through water and food sources, is essential.

Several common classes of pesticides have the potential for dangerous effects on the brain: carbamates (carbaryl), organochlorines (lindane and DDT), organophosphates (malathion), and pyrethroids (permethrin). Lindane and permethrin are available by prescription for the treatment of scabies. DEET is also commonly used to prevent mosquito and tick bites, and can be toxic if not used as directed or if ingested; hand–washing after application is essential.

It is estimated that 50 percent of lifetime pesticide exposure occurs in the first five years of life. Developing fetuses and children are at high risk of pesticide toxicity due to their rapid growth and sensitive organs. Some pesticides have the potential to disrupt hormones. In addition, young children are particularly vulnerable because they spend more time outdoors and often put their hands in their mouths. For some pesticides, breast milk may contain several times the concentrations found in maternal blood samples.