Bisphenol A and Canned Soup
Abstract & Commentary
By Russell H. Greenfield, MD
Synopsis: This brief but important intervention trial was detailed recently in the pages of the Journal of the American Medical Association. The conclusion was that eating canned soup on a regular basis could rapidly increase the body load of BPA, high levels of which have been associated with a variety of illnesses.
Source: Carwile JL, et al. Canned soup consumption and urinary bisphenol A: A randomized crossover trial. JAMA 2011;306:2218.
The researchers behind this randomized, single-blind, 2 X 2 crossover trial set out to quantify the degree of exposure to bisphenol A (BPA) that volunteers (n = 84, median age = 27, 68% female) would experience from the regular ingestion of canned soup. Over a 5-day period, one group ate the contents of a 12-ounce can of vegetarian Progresso soup for lunch, a different type at each sitting, while the other group consumed a 12-ounce serving of fresh soup that had been prepared without canned ingredients. A 2-day washout period followed, and then group assignments were switched, with the five different varieties of soup being offered to participants in the same order. The subjects' diet was otherwise unrestricted. Late afternoon urine samples were collected on days 4 and 5 during each phase of the trial, and urinary BPA concentrations determined.
A total of 75 (89%) subjects completed the trial with median treatment adherence of 100%. BPA was detected in 77% (n = 58) of samples after fresh soup consumption, but 100% (n = 75) of samples after canned soup consumption. The specific gravity-adjusted geometric mean concentration of BPA was 1.1 ug/L (95% confidence interval [CI], 0.9-1.4 ug/L) after fresh soup consumption (unadjusted: 0.9 ug/L; 95% CI, 0.7-1.2 ug/L) and 20.8 ug/L (95% CI, 17.9-24.1 ug/L) after canned soup consumption (unadjusted: 17.5 ug/L; 95% CI, 14.1- 21.8 ug/L). For comparison, the authors reference data showing the 95th percentile level for non-occupational urinary BPA concentration to be 13.0 mcg/L.1 Following canned soup consumption, specific gravity-adjusted urinary BPA concentrations were, on average, 22.5 ug/L higher (95% CI, 19.6-25.5 ug/L) than those measured after a week of fresh soup consumption (P < 0.001), representing a 1221% increase.
The researchers concluded that consumption of 1 can of soup daily over 5 days was associated with significant BPA exposure.
Commentary
Most people are aware of there being health concerns associated with exposure to BPA, if only because so much effort has been expended to remove BPA from infant bottles; however, researchers express concern that adults, too, may be at risk from high levels of BPA. The current paper brings to light a potential BPA source canned goods, where BPA may lurk in the inner coatings that many may not have been aware of previously.
BPA is one of a growing list of chemicals to which the population is exposed that are presumed endocrine disruptors. BPA has been tied to increased rates of diabetes and heart disease, and fears about its potential to promote hormone-sensitive tumors loom large.
With respect to the study at hand, the authors are quick to point out that some may claim "foul" because only a single type of soup product was tested, but the presence of BPA in canned goods already has been well-established, with some of the greatest risks coming from acidic foods present in cans, such as tomatoes. It is unknown how long the elevated levels of BPA may persist after short-term ingestion, but even the short exposure examined in this study caused alarmingly high levels to appear, raising the specter of potential downstream harm.
Until such time that alternative types of can linings are in widespread use, it makes sense to limit exposure to canned food products, especially for acidic foods like tomatoes, and focus primarily on fresh and frozen foods. A great resource for optimizing safety in the age of BPA can be found on the web site of the Environmental Working Group (http://www.ewg.org/bpa/tipstoavoidbpa). n
References
1. Fourth National Report on Human Exposure to Environmental Chemicals. Centers for Disease Control and Prevention, National Center for Environmental Health. Available at: http://www.cdc.gov/exposurereport. Accessed Feb. 14, 2012.
This brief but important intervention trial was detailed recently in the pages of the Journal of the American Medical Association. The conclusion was that eating canned soup on a regular basis could rapidly increase the body load of BPA, high levels of which have been associated with a variety of illnesses.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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