March 18, 2012
Different Toxins For Different Social Classes - In The End We're All Poisoned
New research by scientists from Boston University finds striking associations between chemical body burdens of two different types of chemicals and socioeconomic status. Poor people -- especially young children dependent upon food assistance -- were more likely to have higher levels of bisphenol A (BPA) while wealthier people were more likely to have higher levels of perfluorinated compounds (PFCs).
If confirmed with additional studies, the results may force re-evaluations of the heavy use of canned food in emergency food programs that address food insecurity in families, or, alternatively, developing replacements for BPA-based can liners. Just last week, Campbell's Soup announced they would be shifting away from the use of BPA in their can linings.
In contrast to the food security findings, the scientists found weaker and inconsistent associations between body burden and education or occupation. Mexican Americans had the lowest levels of both chemical types of any racial/ethnic group, and Mexican Americans not born in the United States had much lower levels than those born in the United States.
This is the first study to examine in detail how body burdens of these two chemical types are associated with socioeconomic position, particularly in relation to food security. Food security measures food availability, access and use. The results are consistent with a smaller, earlier study published in Environmental Health Perspectives in 2007.
The current study does not address potential health risks associated with these chemical types. Extensive experimental work with animals, however, has shown that BPA causes an array of adverse effects in exposed animals, including at levels within the range of common exposure that people experience. Effects include behavioral impacts, development changes that increase the risk of mammary and prostate tumors, decreased sperm count and increased risk of type 2 diabetes and obesity. Recent epidemiological studies on BPA with people have reported results consistent with altered neurological development and increased risk of diabetes and heart disease.
Research on the health effects of PFCs is not as extensive as that on BPA. Animal work with PFCs finds development delays in exposed animals and also tumors in certain organs. Research with people reports associations with suppressed immune response, birth weight, cholesterol levels and infertility.
These new results emerged from an analysis of data gathered by the U.S. Centers for Disease Control and Prevention (CDC) in their National Health and Nutrition Examination Survey (NHANES), an ongoing national survey of the health of the American people and of associated risk factors, including body burdens of several hundred chemical contaminants. Participants supplied urine samples and reported socioeconomic information through surveys and interviews.
Dr. Patricia Hunt, a BPA expert at Washington State University who was not involved with this study, says that "common sources of exposure to BPA include canned food, polycarbonate plastic and thermal receipts, such as those issued by ATM machines, gasoline pumps and cashiers in stores."
According to Dr. Glenys Webster, a post-doctoral fellow at Simon Fraser University who studies PFCs and was also not involved in this study, exposure to PFCs can result from their use in "fast food packaging, including microwave popcorn bags, hamburger wrappers and french fry containers as well as their use in stain repellant chemicals applied to carpets and furniture upholstery."
NHANES estimated food security by asking a series of questions. For example: "Were you ever hungry but didn't eat because you couldn't afford enough food?" "Did your child ever skip meals because there wasn't enough money for food?" It also recorded whether the survey participant or a member of their household received emergency food aid.
Overall, body burden of BPA -- as estimated by BPA concentration in the urine -- was higher in children, women and participants with lower incomes. People who received food aid had higher levels of BPA and lower levels of PFCs. The association with low food security and use of emergency food aid was "markedly stronger in 6-11-year-olds."