Although only manufactured for 50 years, between 1929 and 1979, PCBs are considered persistent pollutants because they take a really long time to break down. The pesky chemicals build up in animals, meaning we're exposed if we eat them. The new study, published in the journal Environmental Health Perspectives, studied PCB levels in Native American boys from the Akwesasne Mohawk tribe who eat a lot of locally caught fish, a common PCB-tainted food source.
Studying more than 100 boys ages 10 to 17, scientists discovered that the boys saw a more than 5 percent drop in their testosterone levels, along with a 10-percent increase in PCBs in their bodies.
That's problematic for a number of reasons, as low testosterone has been shown to shorten a man's lifespan and cause difficulties in having children, and is linked to heart disease and other health problems. (Read 11 Surprising Sperm Killers for more information.)
That's not the only problem with PCBs. A recent study found the difference between low and high exposure groups in older women was similar to nine years of aging.
Other reasons to avoid PCBs include:
• Cancer. The Environmental Protection Agency lists PCBs as probable human carcinogens. Even an industry-sponsored, peer-reviewed rat study, characterized as the "gold standard study" by one peer reviewer, demonstrated that every commercial PCB mixture tested caused cancer, the EPA notes.
• Immune System Assault.Animal studies suggest PCBs throw off red blood cells, the thymus gland, which helps regulate the immune system, and the immune system itself, lowering its ability to battle the Epstein-Barr virus and other infections.
• Baby-Making Woes. PCB exposures have been found in animal studies to to reduce babies' birth weight, bring down conception rates, and lower live birth rates.
• Brain Damage. Monkeys exposed to PCBs reliably show damaged neurological development, including a harder time learning and a poorer short-term memory. Studies in humans seem to follow that pattern; PCBs are linked to learning problems.
People can reduce exposure by cutting back on animal products like meat, butter, and other dairy products because the chemicals build up in the food chain. While eating fish brings many health benefits, such as improved brain functioning, it's important to eat fish lower on the food chain, since PCBs often accumulate in larger fish, just as mercury does. If you're a fisherman, make sure to check local fish advisories to avoid PCB overload.
For more information on eating healthier lower on the food chain, check out 9 Super-Healthy, Vegetarian Sources of Protein.