If the food’s in plastic, what’s in the food?

The issue is complicated by questions about cumulative exposure, as Americans come into contact with multiple chemical-leaching products every day. Those questions are still unresolved, says Linda Birnbaum, director of the National Institute of Environmental Health Science, part of the National Institutes of Health. Still, she said, “we do know that if chemicals act by the same pathway that they will act in an additive manner” — meaning that a variety of chemicals ingested separately in very small doses may act on certain organ systems or tissues as if they were a single cumulative dose.

The American Chemistry Council says there is no cause for concern. “All materials intended for contact with food must meet stringent FDA safety requirements before they are allowed on the market,” says spokeswoman Kathryn Murray St. John. “Scientific experts review the full weight of all the evidence when making such safety determinations.”

This article was produced in collaboration with the Food & Enivronmental Reporting Network, an independent, non-profit news organization producing investigative reporting on food, agriculture and environmental health.

Hard to measure

When it comes to food packaging and processing, among the most frequently studied agents are phthalates, a family of chemicals used in lubricants and solvents and to make polyvinyl chloride pliable. (PVC is used throughout the food processing and packaging industries for such things as tubing, conveyor belts, food-prep gloves and packaging.)

Because they are not chemically bonded to the plastic, phthalates can escape fairly easily. Some appear to do little harm, but animal studies and human epidemiological studies suggest that one phthalate, called DEHP, can interfere with testosterone during development. Studies have associated low-dose exposure to the chemical with male reproductive disorders, thyroid dysfunction and subtle behavioral changes.

But measuring the amount of phthalates that end up in food is notoriously difficult. Because these chemicals are ubiquitous, they contaminate equipment in even purportedly sterile labs.

In the first study of its kind in the United States, Kurunthachalam Kannan, a chemist at the New York State Department of Health, and Arnold Schecter, an environmental health specialist at the University of Texas Health Science Center, have devised a protocol to analyze 72 different grocery items for phthalates. Schecter won’t reveal the results before they’re published — later this year, he hopes — except to say he found DEHP in many of the samples tested.

Perhaps the most controversial chemical in food packaging is BPA, which is chiefly found in the epoxy lining of food cans and which mimics natural estrogen in the body. Many researchers have correlated low-dose exposures to BPA with later problems such as breast cancer, heart disease and diabetes. But other studies have found no association. Canada declared BPA toxic in October 2010, but industry and regulators in the United States and in other countries maintain that health concerns are overblown.

Last month, the FDA denied a petition to ban the chemical, saying in a statement that while “some studies have raised questions as to whether BPA may be associated with a variety of health effects, there remain serious questions about these studies, particularly as they relate to humans and the public health impact.”