Children whose mothers are exposed to toxic PFAS “forever chemicals” during pregnancy run an increased risk of low birth weight as well as obesity and high body mass index later in life, an effect similar to prenatal exposure to tobacco, new research finds.
The low birth rate effects of some PFAS have been previously established, but the study tracked 1,400 kids and found higher BMIs and more incidences of obesity in those ages two to five. The “low birth weight-high obesity risk paradox” was previously associated with tobacco smoke exposure during fetal development.
“Something similar is going on with PFAS,” said Joe Braun, a Brown University researcher and study co-author.
PFAS are a class of about 15,000 chemicals often used to make products resistant to water, stains and heat. The compounds are ubiquitous, and linked at low levels of exposure to cancer, thyroid disease, kidney dysfunction, birth defects, autoimmune disease and other serious health problems. They are called “forever chemicals” because they do not naturally degrade in the environment.
A recent review of published research found PFAS in umbilical cord blood in all approximately 30,000 samples collectively checked in the studies.
Though previous research found evidence suggesting the chemicals are linked to obesity early and later in life, including some research from the new study’s authors, the findings were generally inconclusive. The authors say the new research is more definitive because it included a larger sample size, greater geographic coverage, longer timespan and a wider range of exposure levels.
As with tobacco smoke exposure, babies who are born underweight due to PFAS exposure can experience a rapid catch-up in weight, but not height, and the weight gain happens earlier than for children who will be a normal weight, Braun said.
The precise reason PFAS cause these issues is not known for certain, said Jamie Liu, a Brown researcher and study co-author, but she added she suspected the chemicals affect DNA methylation.
The methylation process is related to how the body produces cells, which all have the same DNA. Methylation is part of the mechanism that creates different cells – it determines which cell is an eye cell and which is a kidney cell, for example.
During prenatal development, DNA methylation is one of the “switches that tells the body ‘this is how life is going to be on the outside’”, Braun said.
The authors last year examined markers of DNA methylation in white blood cells and found PFAS exposure seemed to change how the body metabolizes energy from birth up to 12 years of age, which could affect growth.
“PFAS seem to have a programming effect … that lasted for up to 12 years,” Braun said. Overall, the research found about a 12% increase in the likelihood of obesity among PFAS-exposed fetuses.
Those who are exposed can mitigate the effects later in life through regular exercise, Braun said, but it is difficult for mothers to protect themselves and their fetuses because PFAS are so widely used. The US government estimates the chemicals are in 98% of Americans’ blood, and they often have long half-lives, so PFAS from an exposure years before a pregnancy could still harm a fetus.
But, broadly speaking, people can take some steps to reduce PFAS exposure, Braun said. That includes filtering water – the chemicals are thought to be contaminating drinking water for more than 200 million Americans. Indoor dust is another major exposure route, and using a vacuum cleaner that has a Hepa filter can remove contaminants from the indoor environment, Braun said.
Food represents perhaps the most significant exposure route, in part because the chemicals are frequently used in food packaging. Eating fresh foods that are not in packaging and pursuing a balanced diet could be beneficial, Braun added.
“Those are probably the three best things you can do to hedge your bets,” he said.