People who eat out at restaurants, particularly fast-food chains, are at higher risk of exposure to hormone-disrupting chemicals used in plastic, new research has shown.

Study participants who had eaten out the day before had nearly 35% higher levels of phthalates in their bodies than those who at at home.

Phthalates, also known as plasticisers, are used to make plastic more flexible and durable and are used in food packaging as well as shampoos and certain soaps. They have been linked to a long list of health problems, including infertility, birth problems and breast cancer. 

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Certain foods, such as ready-made sandwiches and burgers, were linked to higher phthalate levels, but only when purchased at a restaurant or fast-food outlet.

The research – carried out by Dr Ami Zota, an assistant professor at George Washington University in Washington, and colleagues – used data from 10,253 participants of the National Health and Nutrition Examination Survey (NHANES) collected between 2005 and 2014. They analysed the links between what people ate and the levels of phthalate found in their urine after.

The study is also the first to compare the levels of phthalates in people’s systems after both home-cooked meals and restaurant or takeaway food. Dr Zota recommends prioritising preparing food at home, calling it a “win-win”.

“Home cooked meals can be a good way to reduce sugar, unhealthy fats and salt. And this study suggests it may not have as many harmful phthalates as restaurant meal,” Dr Zota said.

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Three-fifths (61%) of study participants reported eating out the previous day. While the link between the chemicals and eating out was significant for all, certain groups were more at risk. For example, adolescents who ate fast food regularly had 55% higher levels of phthalate than young people eating at home.

Lead author Dr Julia Varshavsky, from the University of California at Berkeley, said: “Pregnant women, children and teens are more vulnerable to the toxic effects of hormone-disrupting chemicals, so it’s important to find ways to limit their exposures.

“Future studies should investigate the most effective interventions to remove phthalates from the food supply.”