Are your plastic food storage containers looking worse for wear? Spaghetti sauce stains are one thing. Scratches, which can harbor bacteria and allow chemicals to leach into your food, are another.

If your containers are old, chances are they contain bisphenol A (BPA), a chemical compound used to harden plastics. According to the Food and Drug Administration (FDA), BPA is safe, at least in the amounts that migrate into our food from plastics and plastic-lined cans. But the FDA does recommend limiting exposure to the chemical. You can buy BPA-free plastics, but if your containers bear recycle code numbers 3 or 7, they may contain BPA.

Research has shown BPA can leach into food or beverages from containers made with the compound, according to Katherine Zeratsky, RD, of the Mayo Clinic. Writing on the clinic website, Zeratsky says exposure to BPA is a concern because the compound might affect the brain and behavior of infants and children. BPA may also alter development of the prostate gland, she says.

Other research suggests a link between BPA levels in the body and the development of Type 2 diabetes . BPA exposure is also associated with heart disease . For these reasons, a number of scientists go further than the FDA, recommending consumers avoid all plastic food containers that contain BPA.

Related: Plastics: A Bunch of Seriously Good Reasons to Just Say No

Protecting yourself from BPA and bacteria

The FDA, the Mayo Clinic and the U.S. Department of Agriculture (USDA) offer these tips:

If your plastic container is scratched, cracked or cloudy, toss it out. BPA is more likely to leach into foods from such containers. The USDA recommends you discard all plastic containers with scratches, “as they may harbor germs and may lead to greater release of BPA.”

Don’t store food in containers you used for non-food items. If you’ve used a plastic container to store detergents, chemicals, batteries or other non-food items, don’t use it to store food, no matter how many times you wash it.

Related: Plastics: Can I Recycle That?

Put the containers in the top rack of the dishwasher only. If you put them in the bottom of the dishwasher you may dealing with shape-shifters, since the heating element at the bottom might warp or melt holes in the plastic. Better yet, wash them by hand.

Don’t use them in the microwave, especially if they are scratched or cracked. Stick to glass and ceramic instead. Many hard, durable plastic containers are made of polycarbonate that contains BPA. The National Institute of Environmental Health Sciences warns you should not use them in the microwave because that may result in more BPA migration into food. “Polycarbonate is strong and durable, but over time it may break down from over use at high temperatures,” advises the NIEHS.

Related: Are Plastic Containers Raising Your Blood Pressure?

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Steve Evans, MA, is an award-winning journalist with more than 20 years experience in daily news, investigative, health and business journalism. Among other jobs, he has served as managing editor of the Central Virginia Newspaper Group, as a senior writer for SNL Financial and as a staff writer for The Progress Index and the Richmond Times-Dispatch.