Non-stick cookware are very popular among consumers for reasons like food not sticking to the surface, less cooking oil needed, less cooking fumes produced, food not easily burnt and easy to clean. However, the safety of the coating coming off non-stick pans has caused public concern. Is the coating paint toxic? How can ingestion of harmful substances be avoided? Let’s probe into the coating material and find out the correct ways of using and cleaning a non-stick pan, which are essential for preventing the release of toxic substances and their migration to food, for the sake of reducing food safety risks.
The interior of non-stick pans is usually coated with polytetrafluoroethylene (PTFE), which is a synthetic compound commonly known as “Teflon”. It is highly resistant to extreme heat and cold (-190oC to 260oC), alkalis and acids, grease and oil, and corrosion, so food does not stick to the inside of the pans easily while being cooked, making them easy to clean. In the past, perfluorooctanoic acid (PFOA)1 and its salts were added in the manufacturing process of PTFE coating. But since the International Agency for Research on Cancer (IARC) classified PFOA as “possibly carcinogenic to humans”2 (Group 2B) in 2017, it is no longer used in the manufacture of non-stick coating for cookware. Some commercially available non-stick pans are labelled “PFOA Free” to indicate that their coatings do not contain “perfluorooctanoic acid” (see Image 1).
Soon after, similar chemicals known as per- and polyfluoroalkyl substances (PFAs) are used for making the non-stick coatings, as PFAs are unlikely to decompose, be released and migrate to food at high temperatures. They are comparatively safe and widely used in the manufacture of food contact products, such as cookware, food wrapping paper and food processing equipment. Nevertheless, when the paint is heated at temperatures above 300oC, it produces fumes containing tetrafluoroethylene (TFE), which is classified by IARC as “probably carcinogenic to humans” (Group 2A) and is likely to pose health risks. Therefore, never heat an empty non-stick pan for a long time during cooking.
The Macao SAR Government Consumer Council has recently released the test results3 on the qualities of 36 non-stick pans sourced from Guangzhou and Macao. Many of the tests for quality assessment of the non-stick coatings, in relation to their hygiene conditions, safety and functions, were based on the national standards set out for “Food Contact Paints and Coatings” and “Performance and Test Methods of Non-stick Surface of Domestic Metal Cooking Utensils for Household Food”. Some of the tests simulated the ways of food preparation of Chinese families. The amounts of potential hazardous substances expected to be released from the non-stick coating due to cooking and friction involved in various types of food and cookware were used as the measurement parameters4. In summary, all the non-stick pans sourced from the local market met the requirements for hygiene, safety and quality in the standards. These included the migration test, in which the solution used in the immersion testing of non-stick pans did not exhibit organoleptic deterioration in colour, turbidity, precipitation and bad smell at the end of the test; the overall migration of coating paint and lead were lower than the national standards of 10mg/dm2 and 1mg/kg respectively; food did not remain in the pans nor cause bubbling or rusting of the coatings easily. So, as long as the non-stick pan is used correctly and its coating shows no signs of obvious damage, consumers should not be overly worried about its quality and safety.
Advice for the public:
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Buy non-stick pans from reliable shops and check the type of coating on the labels and the approved product certification. Choose a safe and suitable cookware with no defects on the coating surface;
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Sharp and hard objects can easily scratch or scrape the coating of a non-stick pan, reducing its non-stick performance and increases food safety risks. It is always advisable to read the precautions and safety instructions before using and cleaning pans. Avoid using metal spatulas and forcibly rubbing pans with a metal scrubber as far as possible (Image 3A) and (Image 3B);
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Do not scrape the non-stick surface hard when cooking, and avoid cooking hard-shelled seafood and food with sharp bones as far as possible;
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Never heat up an empty non-stick pan for a long time to avoid the coating from melting. Since continuous heating at high temperatures can shorten the life span of non-stick pans and cause warping, avoid frying, stir-frying and deep-frying food at high temperatures for extended time periods;
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Do not leave cooked food in the non-stick pan for a long time, move it into an appropriate food container after cooking as soon as possible;
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Stop using any non-stick pan with scraped or scratched coating surface, coating coming off, or cracked coating;
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Allow the non-stick pan to cool naturally after use. Do not pour cold water into the hot pan immediately as the sudden change in temperature can cause warping.
Notes:
1. Perfluorooctanoic acid: In the past, perfluorooctanoic acid (PFOA) and its salts were added in the manufacturing process of PTFE coating of non-stick cookware to stabilise the polymerisation of non-stick plastics. In 2005, the United States Environmental Protection Agency (U.S. EPA) found that PFOA could increase the risk of cancer, cause liver damage and disrupt the endocrine system in experimental rats. Though there is no evidence to date on the adverse impacts of PFOA on humans, the International Agency for Research on Cancer (IARC) classified PFOA as a substance “possibly carcinogenic to humans” (Group 2B) in 2017.
2. Classification of carcinogenic risks to humans by the IARC: https://monographs.iarc.fr/list-of-classifications/.
3. Source: “Report on Comparative Testing of Non-stick Pans by the Consumer Councils of Macao and Guangzhou” released by the Macao Consumer Council on 24 February 2020.
4. Example: A solution of 4% acetic acid and isooctane are used to respectively simulate acidic and oily food for testing the decomposed coating, its overall migration to food, and the amount of lead released. The non-stick performance of the coating is tested by frying eggs, and the corrosion resistance of the coating is tested with vinegar, alkaline noodles, salt solution and other common food ingredients.
008/DIR/DSA/2020
