Eating home-cooked meals reduces exposure to harmful chemicals, researchers say

By Sally Robertson, B.Sc.Oct 10 2019

People who tend to eat home-cooked meals rather than eating fast food, ordering take-out or eating out at restaurants appear to reduce their exposure to harmful synthetic chemicals, according to researchers at the Silent Spring Institute, in Massachusetts.

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The study, recently published in the journal Environmental Health Perspectives, found that those who ate more home-cooked meals had lower levels of chemicals called per- and polyfluoroalkyl substances (PFASs) in their blood.

“To our knowledge, this study is the first to find associations between population-wide PFAS exposures and food consumption from various locations (e.g., restaurants, home),” write study author Laurel Schaider and colleagues.

PFASs are a group of heat- and degradation-resistant chemicals that are commonly used in non-stick cookware, stain-resistant and waterproof products and food packaging.

“Per- and polyfluoroalkyl substances (PFASs) are common industrial and consumer product chemicals with widespread human exposures that have been linked to adverse health effects. PFASs are commonly detected in foods and food-contact materials (FCMs), including fast food packaging and microwave popcorn bags,” writes the team.

Adverse health effects linked to PFAS exposure

The adverse health effects the chemicals have been linked to include cancer, thyroid disease, immunosuppression, decreased fertility, low birthweight and childhood developmental problems.

Studies of adults and children in the US have detected the chemicals in the blood of 97% to 100% of the population.

Since PFASs are ubiquitous and exposure among the population is so widespread, scientists are concerned about the associated health risks.

Eating habits are thought to be a key factor

Dietary habits are thought to be a key factor in how these chemicals end up in the body, which prompted Schaider and colleagues to investigate.

“Understanding sources of dietary exposures to PFASs can inform exposure assessment and identify intervention strategies to reduce exposure,” say the researchers.

For the study, the team analyzed 2003 to 2014 data available for 10,106 participants in the US National Health and Nutrition Examination Survey  ̶  a Centers for Disease Control and Prevention program that monitors health and nutritional trends across the nation.

Participants had provided details about their diet, recalling what they had eaten in the previous 24 hours, 7 days, 30 days and 12 months. They also provided blood samples that were tested for various different PFASs.

We used multivariable linear regressions to investigate relationships between consumption of fast food, restaurant food, food eaten at home, and microwave popcorn and serum levels of perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorohexanesulfonic acid (PFHxS), and perfluorooctanesulfonic acid (PFOS).”

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The more meals were eaten at home, the lower the PFAS level

The more calories people had consumed from food eaten at home each day, the lower the serum levels of all five PFASs, an effect that was stronger among women than men.

For every 1000 kilocalories of food eaten from non-restaurant sources each day, the serum level of PFAS fell by up to 5%. The vast majority (90%) of these meals were prepared using foods bought from grocery stores.

By contrast, consumption of meals from fast food/pizza restaurants and other restaurants was generally associated with higher serum PFAS levels, based on participants’ 24-hour and 7-day recall.

Chemicals from packaging leach into food

For every 100 kilocalories of microwave popcorn consumed each day, PFAS levels were up to 5% higher. Schaider says this is probably due to chemicals in grease-proof food packaging having leached into the food. Four PFAS chemicals that were detected in the blood samples and that were associated with higher popcorn consumption have previously been detected in microwave popcorn bags, notes the team.

"This is the first study to observe a link between different sources of food and PFAS exposures in the U.S. population," she says. "Our results suggest migration of PFAS chemicals from food packaging into food can be an important source of exposure to these chemicals."

No conclusions can be drawn about what effects PFAS exposure may have in the long-term since the survey only asked about recent eating habits. However, it is known that some of these chemicals can stay in the body for years and Schaider and colleagues say “the potential for FCMs to contribute to PFAS exposure, coupled with concerns about toxicity and persistence, support the use of alternatives to PFASs in FCMs.”

Many experts call for the entire class of chemicals to be banned

In recent years, concerns about long-chain PFASs have prompted US manufacturers to replace them with newer varieties. However, these replacement substances are also extremely persistent and research has recently suggested that they too represent health concerns. As a result, many experts have called for restrictions on the entire class of chemicals.

Schaider says that banning the use of PFASs in food packaging, as Denmark recently announced it would do, will lower exposure to the chemicals both among people and in the environment.

Concerns about persistence, mobility, and potential toxicity support a precautionary approach to protecting public and environmental health by avoiding the use of fluorinated chemicals in FCMs entirely.

Schaider and colleagues

Interestingly, a 2017 study by Schaider and colleagues showed that about 50% of fast-food paper wrappers and 80% of paperboard samples did not contain fluorinated substances, suggesting that nonfluorinated options for grease-proof FCMs in the US are available.

Co-author Kathryn Rodgers says that as well as PFASs, plastic food packaging often contains other potentially damaging chemicals such as bisphenol A and plasticizers called phthalates.

The general conclusion here, she says, is the less contact your food has with food packaging, the lower your exposure to PFAS and other harmful chemicals will be:

These latest findings will hopefully help consumers avoid these exposures and spur manufacturers to develop safer food packaging materials.

Kathryn Rodgers