Does the Plastic Additive Bisphenol Cause Heart Disease and Diabetes?

In an article this week in the Journal of the American Medical Association, investigators report that increased exposure to the commonly-used plastic additive bisphenol may be associated with an increased risk of cardiovascular disease and diabetes. Bisphenol A (BPA) is widely used in plastic liners for food and beverage containers, in hard plastics used in bottles, and in many other consumer products.

Investigators measured BPA in the urine samples of over 1400 randomly selected people, who were also asked whether whether they had ever been told by a doctor that they had diabetes, heart disease, and several other medical conditions. The investigators found that BPA was detectable in the urine of over 90% of these individuals. Those who had higher levels of BPA in their urine were also significantly more likely to have reported a history of diabetes and cardiovascular disease. Higher BPA levels were not associated with an increase in cancer or any other medical condition.

This result has led to much speculation in the press about the safety of this nearly ubiquitous chemical, and whether the FDA ought to take steps to remove it or reduce its usage.

What does this study mean?

This study shows one striking fact, and raises several questions that cannot yet be answered.

The fact: Over 90% of Americans are absorbing BPA into their bodies (and excreting it into their urine). So the question of whether we are being exposed to BPA has been answered.

The remaining questions all have to do with whether the BPA we're absorbing is causing or increasing our risk for disease. This study does not answer those questions.

It shows a statistically significant association between higher levels of BPA and diabetes and cardiovascular disease, but an association does not prove a cause-and-effect relationship. For instance, this study also shows an association between being overweight or obese and having higher BPA levels. So, for instance, it is entirely possible that overweight people, on average, eat more packaged food products, leading to higher BPA levels - but that the excess weight itself, and not the BPA levels, produces the excess risk.

The bottom line is that this study has opened new questions about the safety of BPA that will have to be studied in a more rigorous and targeted manner before they can be answered.

Those who want to reduce their exposure to BPA in the meantime can lower their consumption of canned products (including soda pop in cans), and avoid drinking out of hard plastic containers. Soft plastic containers, such as most bottled water containers, usually have little BPA. Here is a report from the Environmental Working Group on the levels of BPA that are found in various canned foods. Read the data, but keep in mind that the rhetoric from this site can be just a tad alarmist (which is to be expected for a group whose mission is to raise alarms about the environment).

_Source:

Lang IA, Galloway TS, Alan Scarlett A, et al. Association of urinary bisphenol a concentration with medical disorders and laboratory abnormalities in adults. JAMA 2008; DOI:10.1001/jama.300.11.1303. Available at: http://jama.ama-assn.org/cgi/content/full/300/11/1303 (Last accessed: September 17, 2008)