By The Editors
In a previous post, we discussed globesity – the escalating global epidemic of overweight and obesity – and said that controlling globesity requires a variety of approaches, including the understanding of the association between obesity and exposure to environmental pollutants.
There are many widespread environmental pollutants that may be contributing to the development of obesity. One of these pollutants is bisphenol A (BPA). In 2012, a study published in the Journal of the American Medical Association indicated that urine BPA is associated with obesity in children and adolescents. Now, results from a study published in the scientific journal PLOS One show that high levels of exposure to BPA might contribute to obesity in girls 9 – 12 years old. The former study involved a U.S. population, while the latter study involved a Chinese population. Therefore, worldwide exposure to BPA in the human population may be contributing to the worldwide obesity epidemic.
What is BPA? According to the US Food and Drug administration (FDA), BPA is an industrial chemical used to make a hard, clear plastic known as polycarbonate, which has been used in many consumer products, including reusable water bottles. BPA is also found in epoxy resins, which act as a protective lining on the inside of metal-based food and beverage cans.
How does BPA get into the body? The National Institute of Environmental Health Sciences tells us that the primary source of exposure to BPA for most people is through the diet. While air, dust, and water are other possible sources of exposure, BPA in food and beverages accounts for the majority of daily human exposure. Bisphenol A can leach into food from the protective internal epoxy resin coatings of canned foods and from consumer products such as polycarbonate tableware, food storage containers, water bottles, and baby bottles. The degree to which BPA leaches from polycarbonate bottles into liquid may depend more on the temperature of the liquid or bottle, than the age of the container. BPA can also be found in breast milk.
In the U.S., BPA has been detected in more than 92% of urine samples, including samples from children. In addition, BPA has been detected in populations from many other countries. The study published in PLOS One was conducted in Shanghai as part of a larger national study of puberty and adolescent health. “This study provides evidence from a human population that confirms the findings from animal studies — that high BPA exposure levels could increase the risk of overweight or obesity,” said Dr. De-Kun Li, principal investigator of the study and a senior research scientist at the Division of Research, Kaiser Permanente Northern California.
Dr. Li and colleagues studied 1,326 male and female children in grades 4 to 12 at three Shanghai schools (one elementary, one middle and one high school). In addition to urine samples collected with BPA-free materials, they obtained information on other risk factors for childhood obesity, such as dietary patterns, physical activity, mental health and family history.
The researchers found that a high urine BPA level was associated with overweight among female students aged 9 –12 years old (likely in pubertal developmental stages), but not in male students. These results are consistent with results from experimental animal studies, where exposure to high BPA level led to weight gain in females, but not in males.
In conclusion, the study suggests that BPA could be a potential environmental obesogen, a chemical compound able to disrupt the normal development and balance of lipid metabolism, which can lead to obesity,
At this point, because the results obtained by Dr. Li and colleagues are consistent with those from studies performed in animal models and other studies performed in humans, it is reasonable to conclude that there is a genuine underlying association between exposure to BPA and obesity.