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Publication Q&A: Ultra-Processed and Fast Food Consumption, Exposure to Phthalates During Pregnancy and Socioeconomic Disparities in Phthalate Exposures

January 2024 – In a recent paper published in Environmental International, Dr. Brennan Baker, in partnership with Dr. Sheela Sathyanarayana of the Center for Child Health, Behavior and Development and Dr. Alison Paquette under the Center for Developmental Biology and Regenerative Medicine uncover links between higher exposures to phthalates and a diet heavy in ultra-processed and fast foods. This study explored potential risk and exposure to harmful chemicals during pregnancy for both the mother and infant.

Read the full publication in Environmental International.

What are the significant findings in this paper?

Processed foods undergo some changes during cooking or preserving, such as adding salt or sugar to peanut butter or canned soups. They are often still recognized as versions of the original, whole foods.

Foods undergoing a more intensified level of processing are commonly referred to as "ultra-processed," and are almost entirely made of substances extracted from food, like oil, sugar and starch. The original, fresh food components are often hard to recognize in ultra-processed foods. A few examples of ultra-processed foods are those containing ingredients like hydrogenated vegetable oils, sugar and emulsifiers as seen in common items like cake mixes, soda, candy and pre-packaged baked goods.  

Some foods are not processed at all, like those obtained directly from plants or animals. Unprocessed foods include fruits, vegetables, and animal products like eggs or fresh/frozen meat, poultry and seafood.

Among pregnant women, eating utlra-processed food and fast food was linked to having higher exposure to phthalates, a class of chemicals found in plastics. This is a problem because phthalate exposure during pregnancy can cause harm to the baby. Phthalate exposure during pregnancy can increase the risk for low birth weight, preterm birth and child mental health disorders like autism and ADHD.

Lower income and education levels were linked with eating more ultra-processed foods, and in turn higher exposure to certain phthalates. Individuals who incorporated more vegetables, fruits, yogurt, fish and nuts into their diets had lower exposure to phthalates.

What does this research tell us that we didn’t know before?

A few previous studies in the general population have shown that people who eat ultra-processed foods have higher exposures to certain phthalates. This is the first study to show that eating ultra-processed food is linked to higher phthalate exposures in pregnant women. This is important because a developing baby is more vulnerable to harmful chemicals than an adult.

This research identifies that higher phthalate exposures in lower socioeconomic individuals could be partially explained by lack of access to affordable, unprocessed foods, leading to higher risk for lower resourced communities.

What are the broad implications of this research?

Ultra-processed foods and fast foods can come into contact with plastics at several points during the production process including food packaging during production, plastic glove use and plastic storage/transportation. Because of this close contact, phthalates can move from plastics into these foods. Eating foods like vegetables, fruits and nuts results in lower chemical exposures because these foods have minimal contact with plastics.

The dietary choice to eat less ultra-processed and fast food could result in lower phthalate exposures. However, the increased costs of healthy, unprocessed foods could prevent people with lower incomes from affording them. For this reason, people with lower incomes may be unable to avoid these chemicals found in ultra-processed foods. This could partially explain socioeconomic disparities in exposures to harmful chemicals like phthalates.

Policy reforms to reduce phthalate exposures should focus on eliminating or replacing these chemicals in food packaging and production materials. Dietary recommendations are a short-term solution that places burdens on consumers, especially those within at-risk communities.

What are the next steps and long-term goals for this research?

We hope this research can help influence government reforms to require safer packaging and improve access to healthier foods for families.

It can be hard for consumers to know about harmful chemicals in processed foods and make dietary choices to avoid them. Reformed government policies to regulate processed foods could help ensure that consumers can purchase food products that are free of harmful chemicals and are safe to eat.

This research could also raise awareness among consumers and manufacturers about harmful chemicals in plastics. Rising awareness could lead to voluntary replacement of harmful chemicals by manufacturers without government intervention.

However, voluntary replacement by manufacturers can be a problem. Often, manufacturers replace one harmful chemical with another chemical that has similar properties but is less well studied. In many cases, researchers uncover that the replacement chemical is equally or even more hazardous than the original chemical. Rather than banning individual chemicals, regulating entire classes of chemicals could prevent this problem.

Any other specific information should we know about this paper?

Washington state is already leading the charge on stricter regulation of harmful chemicals including phthalates and per- and polyfluoroalkyl substances (PFAS).

Seattle Children’s contributing authors:

  • Brennan Baker, PhD
  • Drew B. Day, PhD
  • Alison G. Paquette, PhD
  • Sheela Sathyanarayana, MD, MPH