A slow cooker can be a treasure trove for cooks. Fill it in the morning and you come home to a hot, delicious meal in the evening with only one pot to wash. From soup to chili, casseroles to desserts, braised meat to lasagna, anything cooked in one of these low-energy appliances seems to taste rich, flavorful and always cooked to perfection.
How shocked we were to learn that the glaze on the ceramic insert can leach lead upon heating!
This had been brought to light after consumer reporter Bill Gebhardt of KUTV radio station in Salt Lake City conducted research on the lead content of cookware. He found that 20% of the slow cookers he tested leached significant amounts of lead into food. (1)
Heating up the ceramic insert to 26°C (80°F) leached 10x more lead into food. Keep in mind that the insert is typically heated to over 121°C (250°F). This makes slow cookers a serious source of lead exposure.
Although the U.S. Food and Drug Administration (USFDA) has established “safe” levels of lead in cookware, its policy is misleading—lead poisoning is a cumulative process (2). If even minute amounts of lead are present in your food and leached through your cookware, it can eventually prove toxic over time. It’s been found that even “safe” levels of lead in the body can affect intellectual and cognitive development in children (3).
A Mexican study found that, when heated (in a slow cooker),
“metals present in the glass-clay containers leach into the food and that increased reuse increases the risk to the people who use them in food preparation.” (4).
Later research at Cornell University specifically mentions slow cookers:
“Slow cookers, or crock-pots, are another source of lead in the human diet. Lead is used in the glazed ceramic insert that is in direct contact with the food that is being cooked.” (5).
Acidic foods like tomatoes and citrus can cause greater lead leaching.
There are inexpensive test kits for lead contamination that you can buy online or at your local hardware store to see whether not your cookware at home is safe. Your slow cooker may not be leaching; using a lead test will tell you immediately if it is. If any ceramic container you own that comes into contact with food is cracked or chipped, discard it or find some non-food related use for it; exposed ceramics considerably increase the potential for metal leakage.
Understanding Lead Exposure
If you experience any of the symptoms below, you may want to test (or straight-up ditch) your ceramics.
Symptoms of lead poisoning include (6):
Neurological Effects
- Fatigue
- Headaches
- Hearing loss
- Irritability
- Impaired concentration
- Peripheral neuropathy
- Seizures
- Encephalopathy
Gastrointestinal Effects
- Abdominal pain
- Loss of appetite
- Colic
- Constipation
- Dyspepsia
- Gingivitis
- Nausea
Reproductive Effects
- Miscarriage and stillbirth
- Reduced sperm count and motility
- Abnormal sperm
Renal Effects
- Chronic nephropathy with proximal tubular damage
- Hypertension
- Other
- Anemia
- Joint pain
- Muscle pain
Safer Options
Non-toxic options are available, but beware: Cookware can legally be labeled “lead-free” if the lead content at room temperature is within the USFDA guidelines. This does not mean, however, that leeching won’t occur when the cookware is heated.
Hence, pure clay, clear glass, and stainless steel products are better options. Be aware, however, that a metal container can contain a plastic non-stick coating (Perfluorooctanoic acid [PFOA]) that is almost as toxic as lead. And most substances change when heat is applied, as in the case of the release of lead from ceramic slow cookers. Some clay products may also be coated with metal-containing paints and glazes.
Lead can be found in many places in our surroundings and can be toxic whether inhaled or ingested: water, air, soil, paint, and now cookware. Most lead accumulates and is stored in the bones from where it can be released into the blood.
If you’ve been exposed to lead, a recipe for a metal detoxifying smoothie can be found here.
How To Test For Lead In Your Crock-Pot
You can buy these simple lead testers from Amazon. They’re super easy to use. All you have to do is take a stick and swab it around your slow cooker. If it turns red, then your crock-pot is leaching lead into your food.