If you need another reason to stop eating fast food, this could be it.

New research has found that people who reported consuming more fast food were exposed to higher levels of harmful chemicals known as phthalates.

The study, published by researchers at Milken Institute School of Public Health (Milken Institute SPH) at the George Washington University, is one of the first to look at fast-food consumption and exposure to these chemicals. It appears in the journal Environmental Health Perspectives.

Phthalates belong to a class of industrial chemicals used to make food packaging materials, tubing for dairy products, and other items used in the production of fast food. Other research suggests these chemicals can leach out of plastic food packaging and can contaminate highly processed food.

Lead author Ami Zota, ScD, MS, an assistant professor of environmental and occupational health at Milken Institute SPH, said of the findings:

People who ate the most fast food had phthalate levels that were as much as 40 percent higher. Our findings raise concerns because phthalates have been linked to a number of serious health problems in children and adults.

Zota and her colleagues looked at data on 8,877 participants who had answered detailed questions about their diet in the past 24 hours, including consumption of fast food. These participants also had provided researchers with a urine sample that could be tested for the breakdown products of two specific phthalates – DEHP and DiNP.

The more fast food participants in the study ate, the higher the exposure to phthalates, the researchers found. People in the study with the highest consumption of fast food had 23.8 percent higher levels of the breakdown product for DEHP in their urine sample. And those same fast food consumers had nearly 40 percent higher levels of DiNP metabolites in their urine compared to people who reported not eating fast food in the 24 hours prior to the testing.

Grain and meat items were the most significant contributors to phthalate exposure. Zota says the grain category contained a wide variety of items including bread, cake, pizza, burritos, rice dishes, and noodles. Other studies have also identified grains as an important source of exposure to these potentially harmful chemicals, she noted.

In addition, the researchers also looked for exposure to another chemical found in plastic food packaging – Bisphenol A or BPA. Researchers also believe exposure to BPA can lead to health and behavior problems, especially for young children. While this study found no association between total fast food intake and BPA, Zota and her colleagues found that people who ate fast food meat products had higher levels than people who reported no fast food consumption.

There are many possible routes of exposure, and diet appears to be emerging as a significant one. Phthalates are also found in soaps, perfumes, nail polish, medications, and can be ingested, inhaled, and absorbed through the skin. In 2008, Congress banned the use of phthalates in the manufacturing of children’s toys because of concerns about the dangers of these chemicals.

In 2013, the American College of Obstetricians and Gynecologists released a report stating that high levels of exposure to phthalates could lead to adverse reproductive outcomes in women. Research has linked these chemicals with increased risk of developing fibroids and endometriosis, which can cause infertility, and reduced IQ and behavioral problems in children exposed in the womb.

A 2012 study found a strong association between the presence of DEHP and diabetes. A 2013 study found that exposure to the industrial chemical can increase the risk of various allergic diseases in children. And a 2016 study concluded that it can also negatively affect child behavior.

In fact, the U.S. Department of Health and Human Services warned that DEHP is “reasonably anticipated to be a human carcinogen.”

While there is less evidence that DiNP is problematic, some recent research suggests it very well could be. A study undertaken last year found that exposure to the phthalate was associated with higher blood pressure.

The National Restaurant Association and the American Chemical Society are working together to review the study. They said the levels of phthalates in the CDC surveys are “well below” the levels the U.S. Environmental Protection Agency (EPA) determined are likely to damage health.  But the levels the EPA set for DEHP have not been revised since 1988, and since then, “there has been a wealth of additional scientific evidence suggesting adverse health effects of [DEHP and DiNP] at low levels,” Zota said. And, she added, many of the studies that have found a link between phthalate exposure and reproductive and developmental problems involved populations that had similar low levels of exposure as in the CDC sample.

Large studies that might conclusively link phthalates in fast food and health problems could take years to conduct. In the meantime, Zota notes that it isn’t hard to avoid this particular source:

People concerned about this issue can’t go wrong by eating more fruits and vegetables and less fast food. A diet filled with whole foods offers a variety of health benefits that go far beyond the question of phthalates.