The study adds to mounting evidence that bisphenol chemicals are associated with an increased body mass index in children and teens. It will continue to be an issue "given that human exposure to these compounds is likely to continue to increase in the future," said the study's authors.
Bisphenol S (BPS) and bisphenol F (BPF) are chemicals similar to BPA, which has been used for decades in plastic and metal food packaging, receipts, and electronics. While BPA use in products has declined due to increased awareness about its role as an endocrine disrupting chemical, BPS and BPF are increasingly used as replacements but, as structurally similar chemicals to BPA, they seem to have similar health effects — a phenomenon researchers refer to as "regrettable substitutions.".
Bisphenol chemicals mimic the hormone estrogen and can affect the endocrine system. The main way they enter the body is through leaching out of containers that hold food and beverages; however, they can also be absorbed through the skin.
The new study was led by Melanie Jacobson, a research scientist at NYU School of Medicine. It examined data from the US National Health and Nutrition Examination Surveys (NHANES), which measured urinary BPA, BPS, and BPF levels in 1,831 children and adolescents between 2013-2016. Nearly all study subjects, 97.5 percent, had detectable concentrations of BPA in urine, while BPS and BPF were found in 87.8 percent and 55.2 percent of urine samples, respectively.
The researchers found a correlation between BPS concentrations in urine and being overweight in childhood. As BPS concentration in urine increased, the more likely it was for a child to be obese. BPF detection in urine, meanwhile, was not significantly associated with general obesity – but it was significantly associated with being overweight, and with abdominal obesity specifically.
Abdominal obesity, also called central obesity, is the presence of excess fat surrounding the stomach and abdomen. People who have abdominal obesity are more likely to develop insulin resistance, which can lead to type 2 diabetes and cardiovascular disease.
"Although diet and exercise are still understood to the main drivers of obesity, this research suggests that common chemical exposures may also play a role, specifically among children," said Jacobson in a press release.
The study didn't determine bisphenol exposure as the cause of the children's weight gain, but researchers say it's plausible. Previous studies similar to this one have found associations between bisphenols and obesity, and toxicological studies in micehave suggested that these chemicals play a role by making fat cells bigger and decreasing adiponectin, a hormone that helps regulate blood sugar levels.
One thing that complicates the results is that people who eat more are not only more likely to be obese, but also more likely to be exposed to more food packaging that contains bisphenol chemicals. However, when the researchers controlled for caloric intake, they did not have substantial differences in their findings.
Many products are now labeled BPA-free, but not as many are labeled as BPS- or BPF-free, and it can be hard for consumers to tell if a product contains these chemicals. Some researchers recommend precautionary measures such as avoiding touching receipts, but since bisphenol chemicals are in so many everyday products, exposure can be hard to avoid.
Since bisphenol chemicals are so commonly used, their health effects need to continue to be researched and monitored, said the study's authors. "Replacing BPA with similar chemicals does nothing to mitigate the harms chemical exposure has on our health," Jacobson said.
