Scientists find chemicals found in plastics served at popular fast-food chains

Plasticizers, chemicals added to plastics to make them softer, sturdier, and more flexible, are creeping into fast food, according to a new analysis.

Researchers from George Washington University’s public health school found both ortho-phthalates, an older class of plasticizers whose toxicity lead the U.S. and European Union to restrict their use, and newer replacement plasticizers, whose health impacts are not clear, within orders purchased at popular fast-food chains.

Hamburgers, fries, chicken nuggets, chicken burritos, and cheese pizza were all found to have some plasticizers.

These findings were published Wednesday in the journal Nature.

Scientists have known there’s a correlation between fast food consumption and a high concentration of plasticizers in the body. Fast food components are processed, packaged, and re-packaged in cheap containers countless times before they reach a mouth, creating a succession of potential exposure.

But previous data couldn’t “capture the extent of phthalate and non-phthalate plasticizer contamination across major components of our diet, particularly for vulnerable populations,” the study team writes. This is the first study to measure plasticizer concentrations within American fast food, and these preliminary findings suggest the chemicals are abundant.

What’s new — This analysis presents a look at the commonality of plasticizers in fast food since a new, supposedly safer wave of them was put into use to eventually replace ortho-phthalates.

Now, the two categories exist side by side in the plastics supply.

“This study fills this gap where we need to understand phthalates and these replacement plasticizers in a portion of our diet that is substantial,” lead author Lariah Edwards told Inverse. Edwards is a postdoctoral scientist at George Washington University.

The study claims to be the first to find di-2-ethylhexyl terephthalate (DEHT), one of the newer plasticizers, in food.

Edward and colleagues hired a lab in San Antonio to pick up food from local outposts of:

• McDonald’s
• Burger King
• Pizza Hut
• Domino’s
• Taco Bell
• Chipotle

These franchises were selected for their ubiquity across the United and because they offered samples across the categories of burgers, pizza, and Tex-Mex. The lab tested for 11 kinds of plasticizers using gas chromatography mass spectrometry.

They searched for two ortho-phthalates linked to reproductive health problems and found one of them in 81 percent of foods sampled and the other in 70 percent. They found DEHT in 86 percent of the food items where they looked but the pizza and burritos were not sampled for that chemical.

The concentration of plasticizers was less in pizza, and the fries managed to escape DEHT contamination.

In the second phase of the study, the lab workers asked for a pair of plastic gloves used by the kitchen staff when picking up their food. (Fast food employees were unfazed by this. “Most of them were busy and just went along with it,” Edwards says.)

While DEHT was detected on the gloves, Edwards hesitates to name them as culprits — despite their obvious role in the final handling of the food.

“We can’t identify from our study that that is the source of the contamination but the literature suggests that is a likely source,” she says.

Because fast food is shipped, stored, assembled, and eaten with so many encounters with plastic, they can’t name an exact source.

Why it matters — While consuming trace amounts of plasticizers will not lead to immediate injury, our overall understanding of the health implications is limited because most toxicity studies have been limited to animals.

However, there are signs that consumption isn’t exactly healthy: For example, a 2021 paper linked maternal exposure to high concentrations of ortho-phthalates to impaired child brain development.

Meanwhile, a 2018 study, also from George Washington’s public health school, found that people who ate most of their meals at home had lower phthalate levels than those who ate more often from a cafeteria or restaurant.

Edwards concedes that avoiding fast food may “not be an option” for some. This is, in part, reflects some of the motivation for the study: A lack of data on plasticizers is “particularly concerning from a health equity perspective,” the team writes. “Racial residential segregation impacts food landscapes and dietary behavior.”

Edwards hopes findings of plasticizers in the food supply reach people who have some power over it.

“Broadly thinking,” she says, “we hope this study can inform policymakers because really stronger regulations are what would be helpful to make sure these chemicals aren’t found in foods.”

What’s next — In the immediate, there aren’t many actionable items beyond: If you go for the kind of lunch served with a fountain drink, consider the pizza and maybe go with a vegetarian option.

“Generally we found that foods that contain meat, like chicken burritos and cheeseburgers, had higher concentrations of the chemicals studied, these phthalates and replacement plasticizes,” Edwards says. “So generally you could eat low on the food chain to minimize your exposure.”

Moving forward, Edwards hopes to complete an analysis that looks at fast food samples from around the country for a more certain understanding of the trends.

Abstract: Background: Fast food consumption is associated with biomarkers of ortho-phthalates exposures.However, the chemical content of fast food is unknown; certain ortho-phthalates (i.e., di-n-butyl phthalate (DnBP) and di(2-ethylhexyl) phthalate (DEHP)) have been phased out and replaced with other plasticizers (e.g., dioctyl terephthalate (DEHT)).

Objective: We conducted a preliminary study to examine ortho-phthalate and replacement plasticizer concentrations in foods and food handling gloves from U.S. fast food restaurants.

Methods: We obtained hamburgers, fries, chicken nuggets, chicken burritos, cheese pizza (n=64 food samples) and gloves (n=3) from restaurants and analyzed them for 11 chemicals using gas chromatography mass spectrometry.

Results: We found DEHT at the highest concentrations in both foods (n=19; median =2,510 µg/kg; max=12,400 µg/kg) and gloves (n=3; range: 28% - 37% by weight). We detected DnBP and DEHP in 81% and 70% of food samples, respectively. Median DEHT concentrations were significantly higher in burritos than hamburgers (6,000 µg/kg vs. 2,200 µg/kg; p <0.0001); DEHT was not detected in fries. Cheese pizza had the lowest levels of most chemicals.

Significance: To our knowledge, these are the first measurements of DEHT in food. Our preliminary findings suggest that ortho-phthalates remain ubiquitous and replacement plasticizers may be abundant in fast food meals.