PEOPLE who ate canned soup for five days straight saw their urinary levels of the chemical bisphenol A (BPA) spike 1,200 per cent, compared to those who ate fresh soup, US researchers said on Tuesday.
The study was done by Harvard University researchers and appears in the Journal Of The American Medical Association's Nov 23 issue.
"We've known for a while that drinking beverages that have been stored in certain hard plastics can increase the amount of BPA in your body," said lead author Jenny Carwile, a doctoral student in the Department of Epidemiology at Harvard School of Public Health.
"This study suggests that canned foods may be an even- greater concern, especially given their wide use."
Previous studies have linked BPA at lower levels than those found in the Harvard study to cardiovascular disease, diabetes and obesity in humans, Ms Carwile told AFP in an e-mail message.
Said senior author Karin Michels: "The magnitude of the rise in urinary BPA we observed after just one serving of soup was unexpected and may be of concern among individuals who regularly consume foods from cans or drink several canned beverages daily."
The chemical BPA is an endocrine disruptor that has been shown to interfere with reproductive development in animal studies at levels of 50 micrograms per kilogram of body weight and higher, though it remains uncertain if the same effects cross over to humans.
This study did not measure BPA levels by micrograms per kilogram of body weight, but rather by micrograms per litre of urine.
BPA is typically eliminated in the urine and so any spike can usually be considered temporary. The researchers did not measure how long elevated BPA stayed in the body, saying more study would be needed to examine that question.
BPA is found in the lining of canned foods, cash-register receipts, dental fillings, some plastics and polycarbonate bottles marked with the number 7.
Seventy-five people took part in the study, eating a 12-ounce (340g) serving of either fresh or canned soup for five days in a row. They were advised not to otherwise alter their regular eating habits.
After a two-day break, the groups switched and ate the opposite type of canned soup. A urine analysis showed the canned-soup eaters had 1,221 per cent higher levels of BPA than those who ate the fresh soup.