Living Downstream: A Scientist's Personal Investigation of Cancer and the Environment

DDT is an agricultural insecticide banned in the US in 1972. Contamination comes through eating meat, fish, and dairy contaminated with the chemical and can last a long time in the tissues of animals. DDT is stored in the fatty tissues of humans and can be easily passed on to a fetus or nursing infant through breast milk. Low levels of DDT have an unknown effect on human health; however, high exposure can result in significant health issues, including seizures. While DDT has been shown to cause liver and reproduction problems in laboratory animals, its link to incidence of cancer in humans is likely but not yet proven.

PCBs are human-made, oily liquids or solids used in electrical and mechanical equipment such as transformers, hydraulic fluids, heating fluids, lubricants, and fluorescent lights. PCBs are resistant to extreme temperatures and pressure. According to the Illinois Department of Public Health, PCBs were banned in 1979; however, products made before 1979 still contain them. Due to oil spills, leaks, and improper disposal, PCBs end up in the environment, where they bind to soil and can last. Stored in fatty tissue, they can build up in the body because of contaminated food, air, or water and are often found in fish. Minimal exposure may cause skin discoloration or short-term changes in liver activity. High exposure to PCBs has caused cancer in animals, but PCBs have not been conclusively linked to cancer in humans. They are labeled as likely carcinogens. PCBs have led to birth defects and developmental defects when present within breast milk or the fetus.