Chemicals called perfluoroalkyl substances (PFASs), used for more than 60 years to make products more stain-resistant, waterproof or non-stick, have raised plenty of health concerns. Now a new study from Harvard University suggests the chemicals may also make it tougher to keep off weight.
PFASs are used in non-stick cookware. They are incorporated into clothing, like raingear, to help repel stains and water, and used in furniture and carpeting to make them resistant to stains and liquids. PFASs are also used in fast food and other packaging to keep food from sticking. The chemicals have been linked to high cholesterol, effects on the immune system, hormone disruption, low infant birth rates, and even cancer, according to the US Environmental Protection Agency.
The latest study, published in the journal PLOS Medicine, found that higher levels of PFASs in the blood were associated with increased weight gain after dieting, particularly in women. The compounds are referred to as “obesogens” because they may upset normal metabolism and increase the risk for gaining weight the more people are exposed to them. The study found that people with higher concentrations of PFAS in their bodies also had a lower resting metabolic rate, meaning they burn fewer calories during normal daily activities.
Researchers analysed data from 621 overweight and obese people who took part in a two-year clinical trial conducted in the mid-2000s. The participants lost an average of 14lb in the first six months of the trial, but regained about 6lb over the next 18 months. The people who gained the most weight back had the highest concentration of PFASs, and the link was strongest among women.
“The potential endocrine-disrupting effects of PFASs have been demonstrated in animal studies, but whether PFASs may interfere with body weight regulation in humans is largely unknown,” said Gang Liu, lead researcher for the study and research fellow in the department of nutrition at Harvard T H Chan School of Public Health.
Liu and team found that all individual PFASs were significantly associated with more weight regain in women, but not in men, which was in agreement with some previous studies in which the intergenerational effects of PFASs on body weight were observed only in girls but not in boys. Although the reasons for these gender-specific findings are still unclear, accumulating evidence from experimental research suggests that PFASs are able to interfere with estrogen metabolism and functionalities.
Although the researchers say more studies are needed to confirm their findings, one thing seems clear. These findings suggest that environmental chemicals might play a role in the current obesity epidemic. Given the persistence of these PFASs in the environment and the human body, their potential adverse effects remain a public health concern.
The study’s co-author Philippe Grandjean, adjunct professor in the Department of Environmental Health at Harvard T H Chan School of Public Health, pointed out that we are decades behind in the research because these compounds were first used in the 1950s and not much toxicology was done and there was no legislation. So, in short, it is high time that the authorities concerned took action against yet another health hazard.
