Exposure to common chemicals may be putting millions at an increased risk for serious health disorders.
by John Gever, Staff Writer, MedPage Today
EXETER, England, Sept. 16 — Exposure to a chemical commonly used in food packaging materials may be putting millions at an increased risk for cardiovascular disorders, diabetes, and liver abnormalities, researchers here said.
Urinary levels of bisphenol A (BPA) were significantly higher in people with diagnoses of angina, coronary heart disease, and diabetes, those who had suffered heart attacks, and those with elevated liver enzymes, reported David Melzer, M.B., Ph.D., of Peninsula Medical School, and colleagues in the Sept. 17 issue of the Journal of the American Medical Association.
BPA is a component of epoxy resins used to line food and beverage containers and in polycarbonate plastics contained in many consumer products. It is also present in drinking water and in household air, in the form of dust. Dr. Melzer and colleagues cited data suggesting BPA is detectable in the urine of 90% of adult Americans.
The compound has been found to be toxic at low levels in some animal studies, but with large variations by species.
Explain to interested patients that the study found strong correlations between levels of bisphenol A in urine and the presence of cardiovascular disease, diabetes, and liver abnormalities.
Explain that bisphenol A is used widely in food packaging and other products in daily use in most homes.
Explain, too, that the FDA has tentatively found that the chemical is safe at exposures it considers typical.
Point out that this study cannot confirm causality.
Last month, however, FDA Commissioner Andrew von Eschenbach, M.D., wrote in his weekly column on the agency’s Web site that “the science FDA has reviewed does not justify recommending that anyone discontinue using these products.”
A draft assessment prepared by FDA staffers found that daily exposure to BPA from food packaging materials is less than 3 mcg/kg in adults and less than 0.2 mcg/kg in infants, whereas they calculated a “no observed adverse effect level” of 5,000 mcg/kg from rodent studies.
The FDA is holding a public hearing today on its draft assessment of bisphenol A safety. The JAMA study and editorial were released early to coincide with the hearing.
Using data from 1,455 participants in the National Health and Nutrition Examination Survey (NHANES) from 2003 to 2004 in whom urine levels of BPA and creatinine were measured, Dr. Melzer and colleagues correlated levels of the chemical with the presence of various common disorders.
The researchers found the following odds ratios for each standard deviation of urinary BPA above the mean, after adjusting for age, sex, urinary creatinine, race and ethnicity, education, income, smoking status, body mass index, and waist circumference:
- Angina: OR 1.28 (95% CI 1.09 to 1.50)
- Coronary heart disease: OR 1.63 (95% CI 1.18 to 2.26)
- Heart attack: OR 1.40 (95% CI 1.11 to 1.78)
- All cardiovascular disease: OR 1.39 (95% CI 1.18 to 1.63)
- Diabetes: OR 1.39 (95% CI 1.21 to 1.60)
Mean urinary BPA levels were approximately 4.5 ng/mL for participants not reporting these diseases, compared with about 6.5 to 8.7 ng/mL for those who had them.
The researchers, who made no regulatory recommendations on restricting BPA use on the basis of their findings, also looked for possible associations with cancer, arthritis, overt liver disease, chronic respiratory diseases, stroke, and thyroid disease, but found none.
Although liver disease did not appear to be linked to BPA, the researchers found significant correlations between levels of the compound and elevations in liver enzymes including alkaline phosphatase (P=0.01), gamma-glutamyltransferase (P=0.001), and lactate dehydrogenase (P=0.04).
Correlations with insulin (P=0.06), insulin resistance (P=0.07) and beta-cell function (P=0.09) fell short of significance.
Non-Hispanic blacks had significantly higher mean levels of the compound than non-Hispanic whites. Participants ages 60 to 74 had lower mean levels than those 18 to 29.
Mean BPA levels also tended to be higher in those with body mass index of 35 or greater than those with BMI below 25 — 6.93 versus 2.01 ng/mL — but the difference did not reach statistical significance.
“Independent replication is now needed to confirm the associations reported and to provide evidence on whether the associations are causal,” wrote Dr. Melzer and colleagues.
They noted that the urinary concentrations on which they based their analysis reflect recent exposure. “Repeat measurements over weeks, months, or even years would improve the assessment of longer-term exposure,” they said.
But in an accompanying editorial, Frederick vom Saal, Ph.D., of the University of Missouri, and John Peterson Myers, Ph.D., of Environmental Health Sciences in Charlottesville, Va., said it was not too soon for regulators to act on the new data.
“The study by [Dr. Melzer and colleagues], while preliminary with regard to these diseases in humans, should spur U.S. regulatory agencies to follow the recent action taken by Canadian regulatory agencies, which have declared BPA a ‘toxic chemical’ requiring aggressive action to limit human and environmental exposures,” they wrote.
They alleged that “an aggressive disinformation campaign,” seeking to undermine the reliability of independent scientific findings on the compound’s dangers, has discouraged the FDA and European regulators from restricting BPA use before now.
Drs. vom Saal and Myers said the animal studies on BPA, even without the new findings in humans, represented “overwhelming evidence of harm.”
They added, however, that banning the chemical may not stop its contributions to disease.
“Eliminating direct exposures from its use in food and beverage containers will prove far easier than finding solutions for the massive worldwide contamination by this chemical due its disposal in landfills and the dumping into aquatic ecosystems of myriad other products containing bisphenol A, which Canada has already declared to be a major environmental contaminant,” they wrote.
The study had no external funding. One study author reported having served as a paid independent expert for the United Kingdom Bisphenol A Ecotoxicology Review Panel. Another author reported membership on the United Kingdom Royal Commission on Environmental Pollution and on the board of Natural England. Dr. vom Saal reported having served as an expert witness in litigation involving bisphenol A and is head of a company that offers services related to bisphenol A measurement. Dr. Myers is CEO and chief scientist of a non-profit organization that distributes news related to the environment and health. Dr. Myer also runs a Web site that summarizes emerging science about endocrine disruption including findings on bisphenol A.
Primary source: Journal of the American Medical Association
Source reference: Lang I, et al., “Association of urinary bisphenol A concentration with medical disorders and laboratory abnormalities in adults” JAMA 2008; 300: 1303-10.
Additional source: Journal of the American Medical Association
Source reference: vom Saal F, et al., “Bisphenol A and risk of metabolic disorders“ JAMA 2008; 300: 1353-55.
Reviewed by Zalman S. Agus, MD; Emeritus Professor, University of Pennsylvania School of Medicine.
Published: September 16, 2008
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