Many US military veterans have much higher levels of Pfas “forever chemicals” in their blood than non-veterans, new peer-reviewed research finds, raising more questions about health risks the nation’s service members face after serving at polluted bases.

Ground water, surface water and soil around military bases show among the highest levels of Pfas pollution in the US because the chemicals are used in firefighting foam deployed during training and emergencies. While the problem has been clear for over a decade, the new Brown University-led study is the first to compare levels in veterans’ blood with those in civilians.

The analysis of federal health data found the problem to be concentrated among younger veterans. It estimated that 23 million veterans ages 20–39 have levels of Pfas in blood that are between 13% and 24% higher than non-veterans, depending on the specific compound being measured.

The younger veterans were also more likely to have dangerous levels of Pfas in their blood – they were 18% more likely than young non-veterans to exceed the threshold at which experts suggest people seek medical monitoring.

About 13 million, or 58%, of all veterans in this age group are above the threshold, set by the US National Academies of Sciences, Engineering and Medicine.

“There is some amount of urgency here, and my hope is that this might accelerate the conversations that the government might have about providing [Pfas health monitoring] to all veterans,” said Christian Hoover , a study co-author and a pre-doctoral fellow in epidemiology at Brown’s School of Public Health.

Pfas are a class of at least 16,000 compounds often used to help products resist water, stains and heat. They are called “forever chemicals” because they do not naturally break down and accumulate in the environment, and they are linked to serious health problems such as cancer, kidney disease, liver problems, immune disorders and birth defects.

The military is in the process of phasing out Pfas firefighting foam because the highly toxic substance has widely contaminated water and the environment around more than 720 bases nationwide. The chemicals are also released by burn pits in which the military open burns or incinerates munitions and waste, dispersing a toxic cocktail of chemicals, including Pfas, in the process.

Levels detected in groundwater around bases have been as high as 1.1m parts per trillion (ppt). The EPA has found one of the most widely present compounds increases cancer risk at .004ppt. Despite the clear health risks, blood levels of service members are not regularly tracked. Previous research has found people living near a contaminated base in New Mexico to have elevated levels in their blood compared with the general population.

Brown’s researchers analyzed data from 2003 to 2018 from the US Centers for Disease Control’s National Health and Nutrition Examination Survey (NHANES), a national program that monitors US residents’ health.

It did not find a similar elevation among older veterans. Hoover said that is likely because the chemicals are slowly excreted from the body via blood or urine over months and years, depending on the specific compound.

Older veterans’ bodies have likely expelled the chemicals to a level that is more in line with the civilian population, Hoover said. Disease from Pfas exposure can take many years to manifest, so older veterans who were exposed may be at more immediate risk for developing health issues.

The study’s limitations include not knowing the service members’ occupations, or how or when they were exposed to Pfas. But Hoover said it strongly shows broad level exposures. He said there was a social contract between the government and service members that the government should take care of those who choose to serve the nation after their service is complete.

“If they still believe in that social contract then I would hope they would feel like this may be incumbent upon them to fix in some capacity,” Hoover said.