A new study has linked canned soup consumption with huge increases in urinary bisphenol A (BPA) concentrations (Journal of the Medical Association, November 23/30, 2011, Vol. 306:20: 2218-2220).
Researchers at the Harvard School of Public Health (HSPH) found that a group of volunteers who consumed a serving of canned soup each day for five days had a more than 1,000% increase in urinary BPA concentrations compared with when the same individuals consumed fresh soup daily for five days. The study is one of the first to quantify BPA levels in humans after ingestion of canned foods.
The study adds to the growing body of evidence pointing to the negative health effects of BPA, a synthetic chemical with estrogenic properties that is used in various products, including dental sealants. In animal studies, exposure to BPA early in life has been shown to prompt hormonal and reproductive issues, including abnormalities in the early development of the brain, prostate gland, and breast tissues. It has been linked with cardiovascular disease, diabetes, and obesity in humans.
A key goal of the study was to find the sources of BPA exposure. The researchers noted that canned foods, given their wide use, may be of even greater concern than hard plastics containing BPA.
The researchers, led by Jenny Carwile, MPH, a doctoral student in the department of epidemiology at HSPH, and Karin Michels, ScD, PhD, MPH, an associate professor in the department of epidemiology, set out to quantify whether canned soup consumption would increase urinary BPA concentrations relative to eating fresh soup.
They recruited student and staff volunteers from HSPH. One group consumed a 12-ounce serving of vegetarian canned soup each day for five days; another group consumed 12 ounces of vegetarian fresh soup (prepared without canned ingredients) daily for five days.
After a two-day "washout" period, the groups reversed their assignments.
Urine samples of the 75 volunteers taken during the testing showed that consumption of a serving of canned soup daily was associated with a 1,221% increase in BPA compared with levels in urine collected after consumption of fresh soup.
The elevation in urinary BPA concentrations may be temporary, and further research is needed to quantify its duration, the researchers noted.
