By David Liu, PHD

Tuesday Sept 18, 1012 (foodconsumer.org) -- Exposure to bisphenol A (BPA) may increase risk of obesity and or insulin resistance, according to a new study published in the Journal of Clinical Endocrinology and Metabolism.

Tiange Wang of Key Laboratory for Endocrine and Metabolic Diseases of Ministry of Health in China and colleagues conducted the epidemiological study and found men and women who had the highest amounts of BPA in their urine were 50 percent more likely to have obesity, compared with those whose urine levels of BPA were in the lowest amounts.

Wang et al. reported that BPA can disturb body weight regulation and promote weight gain, obesity, and insulin resistance.   The current study was intended to provide some epidemiological evidence to the association.

In the 3390 men and women aged 40 years or older in Songnan Community, Baishan District in Shanghai, China who participated in the study, those in the highest quartile of BPA in their urine were at 50, 28, and 37 percent increased risk of developing obesity, abdominal obesity and insulin resistance, respectively, compared with those in the lowest quartile.

In men and women with a body mass index lower than 24 kg/m2, compared with the lowest quartile, the highest quartile of BPA was correlated with 94 percent increased risk for insulin resistance.   But this association was not found in those having a BMI of 24 kg/m2 or higher.  

The findings did not mean that BPA did not affect those with a BMI of 24 kg/m2 or higher.  It was possible that these people had more risk factors that overshdow the effect of BPA.

The researchers concluded "BPA was positively associated with generalized obesity, abdominal obesity, and insulin resistance in middle-aged and elderly Chinese adults."

It should be noted that the magnitude of the impact from BPA may vary by country or region.

In addition to obesity, BPA has been linked to a number of other health conditions including breast cancer. But the National Toxicology Program (NTP) only admits or recognizes that "there is some concern for neural and behavioral effects in fetuses, infants, and children at current human exposures. The NTP also has some concern for bisphenol A exposure in these populations based on effects in the prostate gland, mammary gland, and an earlier age for puberty in females."

Bisphenol A is used in polycarbonate plastics and epoxy resins.  Polycarbonate plastics are widely used in food and drink packaging such as water and infant bottles, compact disc, impact-resistant safety equipment, and medical devices.

Bisphenol-A-containing epoxy resins are used as lacquers to coat metal products such as food cans, bottle tops, and water supply pipes. Some dental sealants or composites also contain bisphenol A-derived materials, according to the NTP.