Cancer-linked “forever chemicals” and certain compounds used in plastic production may be associated with a heightened risk of adverse pregnancy outcomes, according to a study from researchers at the University of California, San Francisco (UCSF).

Exposure to these substances — which are all widespread in the San Francisco region — could carry an increased threat of gestational diabetes, life-threatening preeclampsia and pregnancy hypertension in Bay Area individuals, according to a study published Wednesday in Environmental Health Perspectives.

“While many chemicals used in plastics and other products are assumed to be safe, our study adds to a growing body of evidence showing that many of these chemicals are leading to subtle changes in health outcomes that are cause for concern,” lead author Jessica Trowbridge, of UCSF’s Program on Reproductive Health and the Environment, said in a statement.  

Describing prenatal exposures to environmental contaminants as “ubiquitous in the United States,” the authors stressed that fewer than 1 percent of the more than 40,000 chemicals that are processed, imported or used in the U.S. are routinely monitored for their presence in the human body.

Even fewer compounds, they explained, are evaluated for adverse health impacts during pregnancy, even though existing research has shown that such exposures “can have lifelong consequences for maternal and child health outcomes.”

To shed light on the impacts of specific compounds, Trowbridge and her colleagues took maternal and umbilical cord samples from 302 participants in the “Chemicals in Our Bodies” group — a pregnancy cohort within the National Institutes of Health Environmental Influences on Child Health Outcomes Program.

The researchers measured for the presence of two types of “forever chemicals,” PFOS and PFHxS, which are part of an umbrella group of thousands of synthetic and long-lasting compounds, called per- and polyfluorinated substances (PFAS).

These substances, which are linked to thyroid disease, testicular cancer, kidney cancer and other illnesses, are found in certain firefighting foams and a variety of household products, such as nonstick pans, cosmetics and waterproof apparel.

In addition to measuring PFAS levels, the scientists also looked for monoethylhexyl phthalate (MEHP), a common plasticizer; 4-nitrophenol, a known endocrine disruptor used in pesticides, dyes and pharmaceuticals; and tetraethylene glycol, a plasticizer and solvent.

They also assessed levels of deoxycholic acid, a bile acid associated with gestational diabetes, as well as those of tridecanedioic and octadecanedioic acids — two types of fatty acids used in plastic synthesis that had previously only been linked to Reye syndrome, a rare disorder characterized by liver failure.

Ultimately, the researchers detected PFOS, PFHxS, octadecanedioic acid and deoxycholic acid in at least 97 percent of the maternal samples.

Meanwhile, they found deoxycholic acid, tridecanedioic acid and PFHxS in at least 87 percent of cord blood samples — meaning, these compounds readily pass through the placenta.

As far as MEHP, 4-nitrophenol and tetraethylene glycol were concerned, the scientists observed these compounds in fewer than 50 percent of the maternal samples. They therefore excluded these substances from further analyses.

The scientists identified pregnancy complications — gestational diabetes, preeclampsia and pregnancy-related hypertension — by accessing clinical diagnoses and medical records, as well as glucose tolerance tests for diabetes in particular.

They found that 19 percent of participants had a diagnosis of gestational diabetes, 14 percent had gestational hypertension and 7 percent had preeclampsia.

After modeling all the data, the authors observed a trend of increased odds of gestational diabetes as exposure to environmental contaminants rose, with the strongest connections to PFOS, octadecanedioic acid, tridecanedioic acid and deoxycholic acid.

Regarding pregnancy hypertensive disorders — including both preeclampsia and gestational hypertension — they found that exposure to tridecanedioic acid came with the greatest risk.

“The association between these chemicals and an increased risk of poor pregnancy outcomes … should be a wake-up call on the effects of the proliferation of plastic chemicals and PFAS,” senior author Tracey Woodruff, director of the Program on Reproductive Health and the Environment, said in a statement.

“I hope policymakers and EPA regulators will take a good, hard look at the results of this study and others that show a link between plastic chemicals and PFAS and health harms,” Woodruff added.