You are what you eat. And some of what you eat might have come off of your pots and pans. Manufacturers produce hundreds if not thousands of options; many promoting proprietary technologies and coatings designed to make your cookware perform better and require less time and effort. Of course, every manufacturer claims its cookware products are nontoxic and safe.

Are they?

Before you purchase another piece of cookware, educate yourself on what to avoid. Otherwise you could be ingesting small amounts of harmful chemicals.

The U.S. National Library of Medicine states that some metal types used in some cookware can leach into your food if used improperly, or if used at all. The most toxic such chemicals are lead, nonstick polytetrafluoroethylene “forever chemical” coatings, cadmium, nickel, chromium, aluminum and nanoparticles.

Good Cookware

Despite cookware innovations, research indicates that the healthiest choices are still classic materials such as stainless steel and cast iron. Cast iron, without any alloys, chemicals or other additives, is perhaps the oldest and best cooking surface in use today. Carbon steel is similar to cast iron but is a lot lighter. Both are reactive with acidic foods and will leach some iron when cooking them.

Is this iron leaching safe? The short answer is yes. It’s true that excess dietary iron is potentially harmful and can produce heart disease and cancer. But cooking with cast iron involves amounts too small to be harmful. A 1991 Journal of Food Science study found that a typical spaghetti sauce serving of 250 milligrams pulls about 5 milligrams of iron from a pan. This falls far under the recommended dietary allowance of 18 milligrams for women and just under the recommended dietary allowance for men at 8 milligrams. For reference, a typical iron supplement contains 45 milligrams of iron.

It is mostly acidic food (like spaghetti sauce) that strips a measurable amount of iron, and that amount is reduced to negligible levels when you keep your cast iron pan seasoned (oiled). But, if you do use cast iron, it is wise to avoid consuming additional daily “enriched” iron sources (runnersconnect.net).

Stainless steel is also made using iron. A thin layer of chromium oxide prevents the iron from leaching into the food. However, 70 percent of stainless steel is austenitic, meaning that it includes nickel and chromium that can leach into food when an acidic food (such as tomato sauce) is cooked for long periods (tombrimeyer.com). This can be harmful to your health.

Less expensive, nickel-free stainless steel cookware is available, but your pots will be more susceptible to corrosion and won’t last as long. To check for nickel in your stainless steel, apply a magnet to the inside. Nickel inhibits the magnetic properties of stainless steel, so if it has nickel, it won’t stick.

You can get tempered glass cookware to use when you are cooking something acidic. It’s not chemically reactive, even at higher temperatures, and will not leach toxic chemicals. The disadvantage is that it does not have a nonstick surface, so it will take more time and effort to clean.

Bad Cookware

Nonstick pans are very popular, but they come with significant health effects. The original nonstick coating, polytetrafluoroethylene (ptfe), was made with perfluorooctanoic acid (pfoa) but was phased out in 2013 because of links to several types of cancer. But this is still just one chemical in a class of pfas chemicals (also called pfcs) that many believe have carcinogenic effects. These are linked to serious health ailments when cooking at very high temperatures or when the nonstick layer is damaged or wears off.

Aluminum cookware is also popular and inexpensive. Aluminum is a great heat conductor, but it is especially reactive with acidic and salty foods. Elevated amounts of aluminum have been found in the brains of people with Alzheimer’s disease. About 100 studies over the past five years have pointed out that aluminum is a recognized neurotoxin that inhibits more than 200 biological processes within the human body.

Anodized aluminum is designed to be nonreactive to food and leaches aluminum in very small amounts. However, the surface of the protective layer can still be damaged and expose aluminum to the food. And that layer often has nonstick coating on it, such as Teflon or a similar ptfe (SidMartinBio).

The Journal of Food Protection estimates that cooking in aluminum pans can add about 3.5 milligrams of aluminum to your daily intake. While not a health hazard, our daily aluminum intake from all sources is much higher. This is concerning since aluminum is placed in the top 200 health-jeopardizing toxins, according to World’s Healthiest Foods.

Copper is considered the “Cadillac of cookware” because it is the best conductor of heat and many people like its appearance. Copper is toxic to ingest, so copper pots and pans must have a lining of some kind. (Never use unlined copper cookware.) This lining often consists of tin or stainless steel, and since this substance is in contact with your food, you need to know exactly what type of tin or steel it is. In addition, the lining wears away as you cook acidic foods and as you wash the surface, especially if you scour with something abrasive. If you use copper pots and pans, avoid storing food in them, be wary of cooking acidic foods in them, wash and dry them gently, by hand, and do not use them if the lining is worn or scratched (Livestrong.com).

Ceramic coatings are also common, with some cast iron pots and pans having ceramic inner linings. It is a convenient nonstick surface, but the ceramics may contain heavy metals such as cadmium, lead or or titanium dioxide nanoparticles, and may include synthetic bonding substances or Teflon or a type of pfoa, all of which can cause serious adverse health issues.

A University of Southern Denmark study shows that titanium dioxide nanoparticles can travel in our bloodstream and cause brain damage, immune disruption and pre-cancer lesions in the gut. To avoid these particles, don’t scratch ceramic surfaces or cook in them above 500 degrees.

How to Avoid Toxins in Your Cookware

Avoiding or limiting possible toxins and chemicals lurking in your cookware takes some simple steps. First, understand that there are no truly safe cookware coatings. They all inevitably wear down and expose the bare base materials, which results in heavy metal leaching.

Remember that acidic foods exacerbate leaching, so cook them in pots such as cast iron or glassware. Cook at a lower heat, use wooden utensils, and avoid stacking your pots to avoid scratching them. Anything, especially if it has a nonstick coating, should be replaced, especially if that surface is flaked, peeling or scratched.

Healthy, nontoxic cookware includes tempered glass, the proper types of stainless steel, cast iron and carbon steel. With other surfaces, contact the manufacturer to see what types of metals are contained within. And always invest in the best quality you can afford, made to United States standards, while following directions for use and care. This way your cookware will last and be safe to use.