A new study in young adults, which took place in Southern California from 2014 to 2022, found increased blood levels of so-called forever chemicals after eating pork, hot dogs, beef, and other processed meat and drinking tea.

Researchers at the Keck School of Medicine of University of Southern California (USC) published the study in the Environment International journal on Feb. 4.

According to the Centers for Disease Control and Prevention (CDC), synthetic compounds called per- and polyfluoroalkyl substances (PFAS) that resist heat, oil, stains, grease, and water and are used to make food packaging and nonstick cookware are known as forever chemicals because they don’t break down in the environment; can move through soils and contaminate drinking water sources; and build up (bioaccumulate) in fish and wildlife.

PFAS can also take a few days to eight years or more, depending on the specific type, to decrease by half in the human body. Lab animal studies found that PFAS can cause birth defects, delayed development, and newborn deaths, as well as damage the liver and immune system, according to the Agency for Toxic Substances and Disease Registry.

The USC researchers studied blood levels of PFAS and dietary data from roughly 700 young adults, including a group of 123 mainly Hispanic individuals who were tested twice at around age 20 and 24, and another unspecified group of 604 who were only tested once around age 19.

They noted that “Hispanic populations have a higher risk of many non-communicable diseases ... and experience higher exposure to environmental toxins including PFAS.”

Participants answered a dietary questionnaire about various foods they ate, including processed meat, vegetables, and beverages, as well as how often they ate at home and at restaurants, including fast-food restaurants, which use more food packaging contaminated with PFAS.

According to the study, “The strongest positive associations were observed with tea and pork intake.”

An increase of one serving of tea was associated with a higher level of three types of PFAS: 24.8 percent higher Perfluorohexanesulfonic acid (PFHxS), 16.17 percent higher Perfluoroheptanesulfonic acid (PFHpS), and 12.6 percent higher Perfluorononanoic acid (PFNA).

A one-serving increase in pork was associated with 13.4 percent higher Perfluorooctanoic acid (PFOA), another type of PFAS.

“Higher intake of hot dogs (a combination of meat types) was associated with higher PFNA, and higher intake of processed meat was associated with higher PFOA,” the study reported.

A one-serving increase in hot dogs was found to have a 25.4 percent higher PFNA concentration and one of processed meat was associated with a 9.8 percent higher PFOA concentration.

Researchers found that homemade food lowered blood PFAS levels. They also found that whole fruits, cooked grains, breads, pastas, and some vegetables lowered PFAS levels, noting a previous study found “dietary fiber intake has the potential to reduce PFAS concentrations.”

The researchers reported that whole nuts and seeds yielded lower levels of PFAS, but nut and seed butters were linked to higher levels. The researchers speculate that the PFAS-rich grease-resistant packaging contaminates nut and seed butters. Furthermore, they found bottled water, sports drinks, and coffee associated with higher PFAS, which could be caused by PFAS-rich packaging, including tea bags.

Interestingly, the strongest negative associations were observed with sugar. A one-serving increase in sugar intake was associated with 18.9 percent lower PFNA and 13.9 percent lower PFHxS.

A press release about the study from the Keck School of Medicine includes links to other studies about the effects of PFAS.