Low levels of toxic chemicals in homemade food
Many chemicals used at home and in various industries use per- and polyfluoroalkyl substances (PFAS). Several studies have traced these substances in materials used for packaging foods, such as microwavable bags and food containers. A new study shows that eating outside rather than at home is significantly associated with higher blood concentrations of all five of these PFASs, especially in women.
Higher concentrations (at up to 63%) were found with high popcorn consumption, and are probably from microwave popcorn bags. Lesser concentrations were seen with meals comprising fast food, pizzas and other eating places. Eating home-cooked food was associated with the lowest level of PFASs in blood probably due to the limited contact with food-contact materials containing these chemicals.
What are PFASs?
PFASs are synthetic chemicals, which both attract and repel water, as well as being very durable due to the presence of carbon-fluorine bonds. These chemicals are used in making non-stick products, and stain-resistant coatings, as well as fire-retardant foams, and paints, and are also involved in many manufacturing processes. There are well over 4500 of them on the market, and they have been found in drinking water, surface water and wild animals.
Long-chain PFASs are associated with health consequences like immune disease, cancers, thyroid dysfunction, and damage to the reproductive and development functions. These chemicals, which persist in the environment for what seems like forever (actually up to 7 years in the human body), have been removed from production in North America and Europe, but not other parts of the world. They cannot be brought into the US without undergoing evaluation under the Significant New Use Rules first. Meanwhile, short-chain PFASs continue to be used, although they are subject to many of the same limitations, viz., long life, migration out of food packaging into the food itself (especially at higher heat and with longer contact, or with emulsified foods), and toxic effects on the living body.
The researchers retrieved data on the concentrations of PFASs in blood from over 10,000 adults and almost 700 children aged 3-11 years from the NHANES biomonitoring database, from the period 2003 to 2014. They looked at the data from ten PFASs.
They also took a survey on dietary intake patterns for 24 hours, 7 days, 30 days, and 12 months in the form of food frequency questionnaires. For the first, the participants listed all the foods and beverages taken over the previous 24 hours, and these were classified as fast food/pizza restaurants, other restaurants, other sources but eaten at home, and other sources eaten outside home. Total calories were added up, and separately calculated for microwave popcorn and fish or shellfish.
For the 7-day recall, they asked about the frequency of meals eaten from outside the home other than school meals and community programs, and separately from fast food/pizza restaurants. The 30-day recall asked about servings of fish or shellfish. The 12-month recall was based only on food types and used to generate a daily frequency measure.
The study showed the presence of PFASs in 70% of blood samples. Blood levels of these chemicals stayed constant over the study period except for two, PFOS and PFOA, which reduced by 75% and 50% respectively. Fast food consumption was reported by 35% and 70% of adults in the previous 24 hours and 7 days, and by 41% and 84% of teenagers over the same periods, respectively. Fast food/pizza restaurant food intake was significantly linked to higher levels of one PFAS.
86% of people in the study had eaten popcorn in the last 12 months, but only 5% and 7% of adults and adolescents respectively over the last 24 hours. For fish and shellfish, the figures for 24 hours were 10% and 5% respectively, but over 12 months, 89% consumption of seafood was reported.
Almost 85% of popcorn consumption came from microwave popcorn, and the 24 hour recall in the latter group showed that it accounted for about 165 kcal per day. Popcorn consumption was associated with increases in PFASs, and when the daily frequency measure was used, it accounted for a 39% and 63% increase in two different categories of PFASs.
Food not from restaurants and eaten at home was inversely associated with PFAS levels, while food eaten from outside were either positively associated or not linked at all to serum PFAS levels. The study also showed that 50% to 80% of food-contact materials were PFAS-free. This indicates that the switch to safer options for food wrapping to prevent grease leakage are already available in the US.
Exposure to PFASs – the ‘forever chemicals’ as they are called – through food is ongoing and though, with the long-chain PFASs being phased out in the US, newer forms are being used now. The effects of exposure to these are yet to be studied. This exposure occurs not just from food but also from numerous household sources, despite the fact that nobody quite knows what level of exposure is safe, and what toxicity may occur at low exposures. Difficulties in studying these health effects arise from the fact that some of them cause damage only at certain periods of development, which cannot be shown by studying adults.
Another confounding factor is the presence of these chemicals everywhere, making for numerous sources of exposure, and making food exposure that much more difficult to study in isolation. Therefore, researches are needful in studying the diseases linked to specific pollutants in a larger population, . The effects on the environment with such non-degradable chemicals are still more terrible to contemplate, with their ability to contaminate surface water.
The researchers sum up: “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 [food-contact materials] entirely.”
Dr. Liji Thomas
Nationalgeographic.com. (2019). Fast food increases exposure to a ‘forever chemical’ called PFAS. https://www.nationalgeographic.com/science/2019/10/fast-food-increases-exposure-forever-chemical-pfas/
Dietary habits related to food packaging and population exposure to PFASs. Herbert P. Susmann, Laurel A. Schaider, Kathryn M. Rodgers, and Ruthann A. Rudel. 9 October 2019. Environmental Health Perspectives Vol. 127, No. 10. https://doi.org/10.1289/EHP4092. https://ehp.niehs.nih.gov/doi/full/10.1289/EHP4092