The study, which evaluated the levels of BPA in canned drinks sold in Canada, indicated that while most of the drinks analysed contained BPA, the levels present were such that exposure to the packaging chemical was minimal.
According to the study, BPA is used to produce bisphenol A diglycidyl ether (BADGE), the inside coating of food and beverage cans.
The scientists claim that residual amounts of BPA can be present in BADGE as a result of incomplete reaction and that BPA and BADGE can migrate from can coatings especially at high temperatures.
Studies have found that BPA is a potential endocrine disruptor that mimics the action of estrogens, while recent UK research found that higher concentrations of the chemical in urine were linked with heart disease, type 2 diabetes and liver enzyme abnormalities.
A tolerable daily intake (TDI) for bisphenol A was set at 50μg/kg body weight/day by the European Food Safety Authority (EFSA) and at 25μg/kg body weight/day by Health Canada.
The authors of this study claim the trigger for the project was the fact that while previous surveys of BPA in canned foods have been conducted in various countries, there is little information on levels of BPA in canned soft drinks.
They said that they adapted a previously developed method for the determination for BPA in liquid infant formula products and validated it for assessment of BPA levels in soft drinks.
Seven soft drink products including carbonated, non-carbonated, diet, non-diet, fruit flavoured and energy drinks were used to validate the method, continued the scientists, with average detection limits of 0.045μg/l, for a 10 ml sample, being attained.
The team said that they analysed samples of 72 canned soft drink products covering around 84 per cent market share of soft drink products sold in Canada, and that the products were stored at room temperature for between 11 and 12 months before analysis.
The researchers discovered that BPA was present in all but two tonic waters and one energy product from which the chemical could not be recovered. Of the remaining 69 products, BPA was detected in all samples at levels between 0.032 and 4.5μg/l, added the research team.
They said that the highest levels of BPA found were 4.2 and 4.5μg/l, which were detected in two energy drink products.
The authors calculated that an adult of 60kg consuming one canned soft drink per day would, at the average BPA level found, consume only 0.0034μg/kg body weight per day and only 0.027μg/kg body weight per day at the highest BPA level found
They said that this level of exposure compares favourably with the TDI of 25μg/kg body weight per day set by Health Canada. .
The researchers concluded that their work suggests that BPA levels in soft drinks are low compared to those in other canned foods and they indicated that this could be due to the different coatings used in the two piece easy open cans often used for soft drinks or that the amount of coating applied to soft drink cans maybe less than for other foods.
Source: Journal of Agricultural and Food ChemistryPublished online ahead of print: DOI:10.1021/jf803213gTitle: Levels of Bisphenol A in Canned Soft Drink Products in Canadian MarketsAuthors: X.L. Cao; J. Corriveau; S. Popovic.