Fast food packaging may contain potentially harmful chemicals that can get into food, a study has warned.

Researchers carried out tests on more than 400 paperboard containers, paper wrappers and cups from 27 fast-food chains across the United States.

Fluorine was found in nearly half of paper wrappers used to package burgers for example, and 20 per cent of the paperboard containers.

Previous studies have suggested PFASs are associated with child development problem, low fertility and an increased cancer risk.

Research has shown that PFASs from consumer products can also accumulate in landfill sites, migrating into groundwater, and potentially impacting drinking water supplies.

The study's lead author, Laurel Schaider, an environmental chemist at Silent Spring Institute, said: "These chemicals have been linked with numerous health problems, so it's concerning that people are potentially exposed to them in food."

"Children are especially at risk for health effects because their developing bodies are more vulnerable to toxic chemicals," he added.

The findings were published in the journal Environmental Science and Technology Letters.