Scientists have known for many years that chemicals can spill out of food packaging into the food itself. How many chemicals — and in what quantities — depends on the type of packaging and the type of food.

High temperatures can cause chemicals to leach more quickly into food, which is why scientists recommend avoiding microwaving food in takeout containers. Foods that are high in fat or high in acidity also tend to absorb more chemicals from their packaging, as do foods that are tucked into smaller containers — the more cramped the container, the more contact it has with the food inside.

To conduct their analysis, scientists made an inventory of the chemicals known to be in food packaging or food processing equipment, and then searched global tissue databases for evidence that the chemicals had been found in the human body.

“We don’t think about how the (mostly) plastic packaging adds chemicals to our food, but it’s an important source of human exposures,” R. Thomas Zoeller, an emeritus professor of biology at the University of Massachusetts at Amherst who was not involved in the research, said in an email. “This is an early indication that harmful chemicals — largely unregulated — are making it into the human population.”

In a statement responding to the study, Erich Shea, a spokesperson for the American Chemistry Council, a chemical trade group, noted that its members do extensive scientific analyses to verify the safety of their materials. “The report references broad categories of chemistries, each having unique uses and profiles, so it is problematic to group them all together,” he added.

Scientists say that there is a need for better testing of food packaging and further regulations on what is considered safe to put food in. “We need to be thinking about constructive ways forward, how we can ensure the safety of these materials,” Muncke said. “What worries me a lot is that’s not happening.”