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Knowing what your food is in might be as big of a deal as knowing what’s in it: The foils, cans, boxes, and wrappers that house your eats continuously release low levels of synthetic chemicals into your food, says a new study in Food Additives and Contaminants.

Researchers compared databases of chemicals classified as hazardous by European Union chemical regulation standards, and found that a full 154 of them were legal to use in U.S. food packaging. Some chemical highlights: perchlorate, which affects thyroid gland function, tributyltin, which has been linked to immunosuppression, and some forms of asbestos, which increases your risk of lung disease.

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“We are especially concerned about chemicals that affect hormonal activity, known as endocrine disrupting chemicals, or EDCs,” says study author Jane Muncke, managing director of the Food Packaging Forum Foundation in Zurich, Switzerland. “These chemicals can lead to health effects later in life, like predisposition for obesity, diabetes, and cancer, and we don’t know if there are safe exposure levels.”

Though it’s not possible to tell which chemicals are used in which types of packaging (the chemical composition of these wraps and containers is protected by trade secret legislation, and the food manufacturers themselves are only told if it "complies with regulations"), we do know that more than 6,000 chemicals are known to be used in food packaging, Muncke says.

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Muncke suggests protecting yourself with these package-smart habits:

1. Avoid heating food in plastics or coated paperboard. Put your takeout on a plate before warming.

2. Store long-term items like flours, sugars, grains, and cereals in glass, stainless steel, or ceramic containers at home.

3. Buy produce from a local farmers' market or natural food stores that sell in bulk when possible, and bring them home in a linen tote or your own glass or stainless steel containers.

4. Avoid cans, plastics, and cartons whenever possible, and keep them out of heat when you do have them on hand to prevent accelerated leaking of chemicals from their linings.

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