The chemicals bisphenol A and phthalates are linked to obesity and insulin resistance in adolescents in two new studies, but the findings cannot yet answer whether the hotly debated hormone-like compounds are causing the negative health effects they are linked with, experts say.
In one study, the researchers measured the levels of DEHP, a phthalate found in processed foods, in the urine of 766 adolescents ages 12 to 19. They found that teens with higher amounts of DEHP in their urine had increased rates of insulin resistance, a condition that can lead to Type 2 diabetes.
The results held when the researchers controlled for some other risk factors for insulin resistance, such as the teens’ calorie intake and weight.
However, the study does not prove a cause-and-effect relationship. It is possible that insulin-resistant teens tended to eat food with higher phthalates content, or that they excreted more DEHP in their urine compared to healthy children, the researchers said in their study, which was published today (Aug. 19) in the journal Pediatrics.
Another study published in the same journal examined the relationship between bisphenol A (BPA) and obesity in more than 10,000 children ages 6 to18. Children with the highest amounts of BPA in their urine had double the risk of being obese, compared with children with the lowest urinary BPA levels.
In this study too, the researchers recommended cautious interpretation of the results. BPA is found in higher concentrations in fat tissue compared to other body tissues, so it is possible that people with more body fat store more BPA from food, and excrete more in urine, said study researcher Dr. Joyce Lee, professor of pediatrics and endocrinology at University of Michigan.
Another possibility is that people who are obese are merely eating more BPA-containing food, Lee said.
Still far from a consensus.
Eating food packaged in soft plastics doesn’t automatically mean you will gain too much weight or develop obesity, but it does raise your risk. Researchers say one possible explanation for the link is that the types of foods packaged in soft plastics are often highly processed and unhealthy, thus those who have unhealthy eating habits may be more exposed to the identified compounds.
The U.S. Food and Drug Administration has maintained that toxicity tests show current levels of adults’ exposure to BPA is low and safe. However, in July 2012, the agency announced a ban on using BPA in baby bottles and cups after the chemical industry requested the ban, and as the industry was phasing out BPA use. BPA is more highly regulated in several countries, including Canada, as precautionary measures, but officials also generally acknowledge the lack of evidence about BPA’s effects.