Is Silicone Safe? Toxicity Information and Food Safety
Ever since plastics were invented, it seems that their applications across different industries only seem to continue to grow. Plastics are cheaper, lighter, easier to manufacture, have higher water resistance, and are more chemically inert than traditional materials like wood or metals. However, not all plastics are made equal, and not all of them are appropriate for more health-sensitive applications such as cooking or baking.
Silicone has become one of the most popular plastics used in households nowadays. It can be found in baking mats, cupcake molds, candy molds, muffin tins, tongs, spatulas, and oven mitts. With its level of ubiquity, silicone has also been the subject of a lot of safety concerns. Once and for all, we answer the question of whether silicone cookware or bakeware is safe.
What is silicone? Why is it so popular?
First off, silicone is not to be confused with silicon. While silicon is a naturally-occurring element, silicone is a polymeric compound consisting mostly of silicon, carbon, and hydrogen atoms. Depending on the application, silicone can be in solid, liquid, or gel forms. The hardness or flexibility of the final silicone product is determined by the precursors used during the synthesis process or the addition of compounds that create “branches” in the polymer chain.
Silicone has some useful characteristics that have made it a desirable compound for several different applications. It is water-repellant and can form completely watertight seals, making silicone an excellent material for caulking. It has also been used for thermal and electric insulation owing to its low electrical conductivity and thermal stability. Silicone has also been extensively used in the construction and automotive industry as material for coating, fire protection, and external gaskets due to its resistance to degradation by oxidation, ozone, and ultraviolet light.
The thermal stability of silicone, coupled with its resistance to microbiological growth, has made it an essential part of many kitchens. Certain grades of silicone have been considered FDA-compliant and have made their way to households in the form of various bakeware and cookware. Nowadays, you can get silicone molds for muffins, cookies, and candies. Its non-stick capabilities also make silicone an excellent material for reusable mats for baking sheets. Kitchen utensils and pot holders greatly benefit from the insulating capabilities of silicone.
It also helps that silicone can be manufactured into a lot of creative shapes and in a variety of colors. Aside from the versatility of silicone as a material, cookware and bakeware made using silicone just look great. They come with this whimsical and playful visual appeal, which is so different from the industrial look of their stainless steel and aluminum counterparts. If you’re going for an Instagram-worthy kitchen setup, then silicone cookware sounds like an attractive addition.
What is food-grade silicone? Is it safe?
Not all types of silicone are appropriate for food applications. The matter of determining whether a particular piece of silicone is food-grade or not depends on its purity. Food-grade silicone does not contain any chemical fillers or byproducts, making it completely non-toxic and safe for direct food contact.
While silicone innately has properties that make it suitable for food handling, not all silicone products or manufacturers are automatically awarded the “food-grade” label. Each manufacturer must demonstrate compliance with standards set by the Food and Drug Authority (FDA). According to FDA regulations, a food-grade material must demonstrate an ability to keep food safe and sanitary when subjected to exposure to all stages of food manufacture, presentation, and transportation. Food-grade materials should also exhibit stability when in contact with aqueous or fatty foods. A manufacturer that has demonstrated the ability of their products for safe food contact are issued the appropriate FDA certificate.
On paper, silicone sounds like excellent material for cookware. It’s heat-resistant, chemically inert, and does not promote microbiological growth. Selected silicone products even come with an FDA certification to boot. But how safe is silicone in practice? Can it withstand exposure to heat and oils without leaching off toxic compounds? Are there any long-term effects of using silicone cookware?
1. Studies have shown that silicone can release certain compounds when exposed to high temperature and high-fat foods
Despite the claims that silicone is thermally stable, several studies have indicated that silicone tends to break down into its monomers – the individual constituents of the polymer – when exposed to high temperatures. These monomers, called siloxanes, are small compounds that also contain silicon, carbon, oxygen, and hydrogen. In almost all studies, the release of siloxane was also associated with exposure to food with high-fat content.
It’s worth noting that the contamination of siloxane was shown to be very low. In one study, the highest migration observed resulted in a concentration of 177 mg of siloxane per kg of a piece of meatloaf. Small amounts of siloxane are not a problem, but frequent and repeated use of silicone cookware may lead to accumulation of this compound inside the human body. Siloxane release was observed when silicone was exposed to temperatures of around 300 °F.
2. Cheap silicone products may come with toxic additives
Food-grade silicone is supposed to have no additives which may get leached off when the product comes into contact with the food. This is, however, not always the case. Cheap silicone cookware may not be food-grade at all and may come with non-silicone fillers like other plastics. Moreover, the colorants added to silicone to make more visually appealing products can also be the source of toxic byproducts.
Tips on using silicone bakeware and cookware
It seems silicone is not the all-around lightweight cookware and bakeware material we were hoping it would be. Should you be throwing out your silicone muffin tins and not but silicone anymore? Of course not. With mindful selection of silicone products and proper care, you can still safely take advantage of the benefits of silicone.
1. Make sure to get 100% food-grade silicone
The key to silicone being food-grade is its purity, so always check the label of a supposedly food-grade silicone before buying it. When in doubt, you can even try twisting or stretching a silicone product. If a section of the product turns white when stretched or twisted, then it likely contains fillers.
2. Buy good quality silicone cookware from a reputable manufacturer
Although the FDA only grants food safety certification to manufacturers who have subjected their products to a battery of tests to ensure their integrity, nothing’s stopping dubious manufacturers from claiming that their silicone products are “food-grade.” If a silicone product seems too cheap, then you would do well to question its source. We have even heard of reviews of cheap silicone baking mats outright melting after just a single use. To make sure you don’t waste any food, we recommend buying your silicone products only from reputable and well-known manufacturers who can assure FDA compliance.
3. Check that the product is BPA-free and lead-free
Almost all plastic products available nowadays that are made for food contact are free from bisphenol (BPA) and lead. BPA has been mainstays of the plastic industry up until a few years ago when they were shown to be potentially toxic. In the same vein, lead was a common pigment ingredient until it was banned in the 1970s for its toxic effects. To be sure, look for products that are clearly labeled to be free from these ingredients.
4. Avoid high-temperature applications
Based on detailed studies done on various pieces of silicone bakeware and cookware, silicone really only releases a significant amount of siloxane when exposed to high temperatures. Although contact with high-fat foods seems to encourage this release, the heat is still the more crucial component. For now, we recommend skipping the use of silicone for baking and for high-temperature cooking. Perhaps using your good old aluminum tin and lining a baking tray with parchment paper the old-fashioned way are still the better alternatives.
It’s easy to be attracted to the fancy silicone kitchen products that can be found everywhere nowadays. They are flexible, non-stick, much lighter, and come in a variety of cute shapes and colors. However, we advise exercising a bit of caution when using silicone kitchenware, even food-grade ones.
Currently, there has not been any overwhelming scientific proof that silicone can remain perfectly stable when exposed to high temperatures. Many detailed studies even suggest the opposite: exposure of silicone kitchenware to high temperature and high-fat foods can result in leaching of the siloxane, the plastic’s monomer material.
This does not mean that silicone has no place in your kitchen. You might want to skip on using silicone for baking, but you can still use silicone for candy or ice molds. Silicone oven mitts are some of the most useful items you can get, as silicone has excellent thermal insulation. You can also get silicone lemon squeezers, garlic peelers, and measuring cups. Being lightweight and flexible, these pieces of silicone kitchenware are easy to put away. Despite the popularity of silicone kitchenware, it is still a relatively new technology which may still improve in the near future.