Bucks and Montgomery County residents who live near military bases had higher levels of four “forever chemicals” known as PFAS in their blood than the typical American, according to federal health officials.

The chemical compounds are associated with higher levels of cholesterol, which is linked to increased risk of heart disease and stroke.

Those were among preliminary findings released Monday from research designed by the Centers for Disease Control and Prevention (CDC) and the Agency for Toxic Substances and Disease Registry (ATSDR). The work is one of the largest cross-sectional studies designed to figure out how PFAS exposure from drinking water may affect health.

The Inquirer reported on initial findings earlier this month that nearly all adults and children who live near the military bases had detectable concentrations of seven different compounds known under the umbrella term per- and polyfluoroalkyl substances, or PFAS.

The federal study tested the blood of participants from eight states from 2019 to 2023 for PFAS, human-made chemicals used since the 1940s to make waterproof garments, nonstick pans, grease-resistant items, and firefighting foams. They are often referred to as “forever chemicals” because they resist breaking down in humans and the environment.

Pennsylvanians living near the suburban military bases had among the highest average levels of at least four PFAS compounds among those tested across the eight states. The health impact, if any, was unclear from the preliminary results that were released.

For example, the 1,252 adults and 89 children living near the bases had an average of 3.6 nanograms per milliliter (ng/ml) of the compound known as PFHxS in their blood. PFHxS was associated with higher blood pressure in the study. The national average was 2.1 ng/ml.

Study participants from Pennsylvania lived near the Horsham Air Guard Station and former Naval Air Station, Joint Reserve Base Willow Grove, and the Naval Air Warfare Center Warminster site, where aqueous firefighting foam was widely used. The foam contained PFAS to create a film on a fuel surface to smother flames and suppress vapors.

Researchers stressed that the results are preliminary, subject to change, and that no definitive conclusions have been made. Indeed, some findings were contradictory, finding that higher levels of some PFAS equated to lower associations of some health outcomes. They will present more details at a conference in August.

They looked at possible health outcomes of PFAS on lipids, thyroid issues, diabetes, blood pressure, metabolic syndrome, heart disease, and obesity.

Lipids: Higher cholesterol overall in adults

Marian Pavuk, a public health researcher, said the study measured total cholesterol, including HDL and LDL, and triglycerides in adults over the age of 18. It found that higher blood levels of five PFAS compounds were associated with higher levels of cholesterol overall. But they were not linked to higher triglycerides.

Some PFAS appeared to have stronger associations with cholesterol levels than others, he said.

Researchers plan to study PFAS levels of children and lipids next.

Thyroid: Different outcomes by gender

The thyroid regulates metabolism, growth and development, mood, and reproduction, and synthesizes the hormones thyroxine and triiodothyronine. Insufficient levels of hormones result in hypothyroidism. Excess results in hyperthyroidism.

Overall, higher levels of PFAS were associated with a lower prevalence of hypothyroidism, said Michael Bloom, a professor at George Mason University.

However, in females, higher levels of PFHxS were associated with a higher prevalence of hypothyroidism.

In males, higher PFOS, a specific type of PFAS, was associated with a higher prevalence of hyperthyroidism, he said.

Diabetes: Not much impact

Ann Starling, an environmental public health researcher, said previous studies were contradictory, with some showing those with higher levels of PFAS as more likely to develop type 2 diabetes. However, some showed no relationship.

This study looked at whether there was a relationship between exposure to PFAS and blood markers of diabetes, such as glucose, insulin, and A1c.

About 12% of the adults in the study had diabetes, similar to the U.S. population. Diabetes was not more likely to be detected among participants with higher PFAS levels, Starling said. In fact, some participants with higher blood PFAS levels were less likely to have diabetes.

Blood pressure: Increases in younger adults

Researcher Yuting Wang said exposure to PFAS has in previous studies been associated with an increased risk of pregnancy-induced high blood pressure and preeclampsia, a pregnancy condition marked by high blood pressure.

Wang said higher PFOS and PFHxS were associated with higher blood pressure. The effects were stronger in younger adults aged 18 to 29, Wang said. And the effects were stronger on adults 25 to 30 years who fell into the midrange of body mass index.

Metabolic syndrome: Some impact

Scientist Abby Bline said the study looked at metabolic syndrome, an umbrella term for a group of conditions that increase the risk of cardiovascular disease. The study examined MCP-1 and PAI-1, substances bodies make that occur at higher levels in people with metabolic syndrome.

Researchers used waist size, HDL cholesterol, triglyceride, blood pressure, and glucose levels as factors in determining who had metabolic syndrome.

Overall, people with higher PFOA and PFOS levels were less likely to have metabolic syndrome than people with lower levels.

However, higher levels of the compounds in the blood were associated with higher levels of MCP-1. And higher PFOS and PFHxS were associated with higher levels of PAI-1.

Heart disease: No association with PFAS

This is the leading cause of death in the U.S. Some previous studies have linked PFAS to an increase in cardiovascular diseases. Others have shown no association.

Of all study participants, 528, or 9.1%, reported they had heart disease.

Celina Phillipson, a researcher, said most PFAS showed no association to heart disease.

Obesity: Less likely

Yerin Jung, a researcher, said the study looked at obesity indicators such as body mass index, waist circumference, waist-to-hip ratio, and body roundness index.

The study found that participants with higher PFAS levels were less likely to be obese.

Overall, the researchers said conclusions about cause-and-effect relationships are limited, because they don’t know the levels of PFAS in blood before any diseases developed.

Further, they said that participants were tested after they had already stopped drinking PFAS-contaminated water. Their levels of PFAS were likely higher before they stopped drinking it.

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