The impacts of toxic ‘forever chemicals’ are not the same for women and men

This story is part of a series, “Fighting ‘Chemicals Forever’: Women Face Widespread PFAS Risks.”

While “forever chemicals” have been linked to numerous adverse health impacts, from cancers to kidney disease, they can also have disparate impacts on male and female bodies.

“Often you see something in one sex and not the other,” said Linda Birnbaum, former head of the National Institute of Environmental Health Sciences and the National Toxicology Program.

“Forever chemicals,” or PFAS, can be found in many common household products and certain types of firefighting foams. Their use in industry has led to their proliferation in the air, water and soil, and it is estimated that they are in the blood of about 97% of Americans. The federal government recently established the first national limits for some types of these substances in drinking water.

Some of the different ways that penetrating chemicals affect men and women are clearly linked to the reproductive organs.

Exposure to PFAS is associated with an increased risk of testicular cancer, for example: A panel of scientists established in 2012 that there is a “likely link” between exposure to a type of PFAS called PFOA and testicular cancer.

A January 2022 Toxicology Review explored various subjects related to the female reproductive system – such as birth defects, fertility and changes in the menstrual cycle – which may be related to exposure to PFAS. “The effects are many,” the authors found, although they say it is still unclear exactly how the substances reach the female reproductive and endocrine systems due to “a large gap in research.”

A study published in September sought to narrow that gap by focusing on sex-specific relationships between three classes of likely endocrine disruptors – including PFAS – and previous diagnoses of hormone-related cancers. The scientists saw particularly striking indications of these differences when it came to melanoma: Higher levels of PFAS in the blood were associated with earlier diagnoses in women but not in men.

“Sex-specific associations between PFAS chemicals and prior melanoma diagnosis suggest that sex-mediated mechanisms may be at play,” wrote the authors, from the University of Southern California and the University of Michigan.

Although the precise mechanism behind the link to melanoma is still unclear, scientists have surmised that because these tumor cells have estrogen receptors, environmental contaminants that mimic estrogenic activity – such as PFAS, potentially – could be fueling the growth of melanoma. cancer in women.

Similar to melanoma, other health impacts that are not as obviously linked to sex-specific characteristics may still affect men and women differently after exposure to environmental contaminants such as PFAS.

High blood pressure, for example, appears to be more pronounced in women than in men, recent studies have revealed.

Sometimes this manifests itself in pregnancy-induced hypertension, which can lead to a potentially fatal condition called preeclampsia — a potential effect of PFAS exposure that Erin P. Hines, a researcher in the Environmental Protection Agency’s division of reproductive toxicology, says. She said she was looking forward to seeing more research on it.

“Having preeclampsia or pregnancy-induced hypertension during pregnancy can alter a woman’s health outcome for the rest of her life, putting her at greater risk for adverse cardiovascular outcomes such as stroke,” Hines said, noting that this risk is independent of exposure to PFAS.

“But if you have a pregnancy with preeclampsia or one of these hypertensive disorders of pregnancy, throughout your life, there are increased risks of morbidity and mortality associated with [with] cardiovascular events,” she added.

In addition to the pregnancy-induced type, additional research has also largely identified hypertension in the female population exposed to PFAS.

A 2022 Study in American Heart Association found that middle-aged women with higher blood levels of certain types of PFAS had a higher risk of high blood pressure. Analyzing the annual follow-up visits of 1,058 middle-aged women who were initially free of hypertension between 1999 and 2017, scientists found that 470 individuals developed the condition. The authors determined that women ages 45 to 56 who had high concentrations of PFOS in their blood had a 42% greater chance of developing high blood pressure, while those with high concentrations of PFOA had a 47% greater chance. Women who had high concentrations of all seven types of PFAS examined in the study had a 71% greater risk of developing high blood pressure.

Study author Ning Ding said PFAS exposure also appears to put women at especially high risk more broadly.

“Women appear to be particularly vulnerable when exposed to these chemicals,” said Ding, a postdoctoral fellow in the department of epidemiology at the University of Michigan. in a statement. “Exposure may be an underappreciated risk factor for cardiovascular disease risk in women.”

Studies are also emerging that suggest links between PFAS and other health outcomes in girls or women, like ADHD in girls or weight gain in women. Scientists have also linked PFAS exposure to an increased susceptibility to developing diabetes among middle-aged women. Some types of PFAS may disrupt the regulatory behavior of certain protein molecules and, in turn, increase the risk of diabetes in this cohort, according to the April 2022 Study.

Although the researchers emphasized that evidence of sex-dependent links between PFAS and diabetes in humans is lacking, they pointed to another recent study showing that the metabolic responses of female mice to PFOA exposure were greater than those of male mice.

Meanwhile, another impact of PFAS has been shown to primarily affect boys. One 2022 study found that Teenage boys exposed to a mixture of these substances and another type of hormone-disrupting chemicals known as phthalates may have lower bone density – which makes bones weaker and more prone to fractures.

Some vulnerabilities associated with PFAS can take root in the womb. Prenatal exposure to substances has been linked to premature births, changes in birth weight or congenital problems that manifest later in childhood — including ADHD or IQ effects, according to Birnbaum.

“We’re seeing with PFAS — like a lot of chemicals that really disrupt hormonal systems — that you get a difference between a boy and a girl,” she said, noting that some effects are showing up in just one sex.

“If you look at, say, boys and girls together, you might not see any effect. But if we separate the sexes, suddenly we can see an effect on one of them,” added Birnbaum.

But she also acknowledged that not all investigators are open to this kind of separation: “What’s interesting to me is that there are some people who don’t want to believe it. They think, well, if you don’t see it in both, you know, men and women, this can’t be happening.”

Uncovering sex-dependent health impacts often depends on what, exactly, scientists are looking for in their research, according to Birnbaum.

“It’s kind of an old story: if you don’t look, you don’t see. But when you start looking, you start finding.”