Few chemicals have generated the controversy of bisphenol A, a building block for certain plastics and food can liners. The controversy continues in spite of recent studies which show that human exposures to BPA are far below levels that have been shown to cause adverse effects in animals.
Among these studies is a recent one funded by the Environmental Protection Agency and conducted by researchers at the Food and Drug Administration, the Centers for Disease Control and Prevention and the Pacific Northwest National Laboratory.
In this study, blood and urine samples were collected hourly over 24 hours from volunteers who ate only at the laboratory. Their diets were enriched with canned food so they would have relatively high intakes of BPA. The researchers found that the majority of blood samples contained BPA levels below the limit of detection, and virtually all BPA was eliminated from the body in urine.
This EPA-funded study was further supported by another study conducted by a government organization in Europe. Scientists at the European Commission Joint Research Centre’s Institute for Health and Consumer Protection tested how much BPA migrated out of polycarbonate plastic baby bottles into the bottles’ contents.
Following the manufacturer recommendations, the 40 bottles were sterilized in boiling water for five minutes.
Then, a preheated liquid simulating milk was added to the bottle and maintained for two hours at 70 degrees Celsius, representing a “worst-case scenario,” according to the study authors.
This was then repeated twice more, for a total of three migration tests for each bottle.
Using a robust method that was able to detect very low BPA concentrations, down to 0.1 parts per billion, the European researchers found that no BPA was detected migrating from 32 of the bottles. Very little migration occurred from the remaining eight bottles, and most of these didn’t release detectable BPA in the second or third tests.
Only one bottle, with a migration level of 1.08 ppb in the first test, still showed a detectable level of BPA in the last test (0.42 ppb). In all cases, the BPA concentrations were substantially below the European Union migration limit of 600 micrograms per kilogram of food.
The researchers concluded, “This confirms that the likelihood of migration of BPA is very low and remains at very minute amounts.” This means babies could only be exposed to minute levels of BPA from polycarbonate baby bottles and is consistent with low blood and urine levels of BPA measured in adults.
It also shows that BPA exposures from baby bottles are much lower than exposures demonstrated to cause effects in animals, even those reported in “low-dose” studies.
It is notable that studies claiming effects from BPA on infants and toddlers receive considerable media attention.
In contrast, studies which tend to allay concerns over BPA, such as this recent research from Europe, receive significantly less media attention.
Dr. Julie Goodman, a board-certified toxicologist, teaches at the Harvard School of Public Health, is a consultant at Gradient in Cambridge, Mass., and works with companies that manufacture and use BPA.