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Choosing safe cookware is an important part of creating a non-toxic, healthy home. After all, cookware comes in contact with the food we eat, often for prolonged periods of time. High temperatures, which our cookware is subject to, can increase migration of toxics and toxins from the cookware and into our food. Also, fumes from the cookware can be inhaled while we cook. So, what are the best types of cookware to use and what should be avoided?
This guide will answer those questions and tell you what brands fall into each category. Unfortunately, there is no cookware material that is perfect and without issue. It’s best to select several different types of safer cookware and rotate them. That way, you will reduce exposures from any one type of material.
I’ve rated each category with a letter grade using the following criteria:
- Products are well tested by independent organizations and ingredients are well disclosed and understood.
- Products are tested by independent organizations but may contain additives that are not well disclosed.
- Products have limited testing and additives that are not well disclosed.
- Products are not well tested and have ingredients with known health concerns and/or ingredients whose health effects are not yet understood.
- Products are known to release materials with known health concerns.
There are not currently any categories with a grade of “B”. Some products that are graded “C” could move up to a “B” with more thorough testing.
Glass has been used for centuries to store food and is generally considered to be the safest material for this purpose. Concerns have been raised recently in blog forums about the presence of lead in glass, including glass cookware. Lead is not typically added to glass as an ingredient, except for leaded crystal which should be avoided. However, lead is everywhere in the environment and any raw material is likely to have some degree of lead contamination.
So, is there lead in glass cookware and does it leach into food?
Glass cookware is made from glass ceramic, which has the same chemical composition as glass but is treated with heat to crystallize the glass. An extensive study done on several types of glassware, including glass ceramic, tested products under several testing conditions including acidic solutions cooked for long periods of time. The glass ceramic products had no detectable levels of lead under any test conditions. You can read more here about the study and other types of tested glassware. Glass ceramic is non-porous so it does not leach or react with acidic foods.
Look for glass cookware and bakeware that meets or exceeds California Proposition 65 standards for lead and cadmium for extra assurance.
Glass ceramic cookware is among the healthiest options but it is not without risk. Shattering is a concern with any glass cookware but glass ceramic is more tolerant of temperature changes and therefore less likely to shatter. Borosilicate glass is less likely to shatter than soda lime glass. All glass cookware should be used with caution and it’s important to carefully follow manufacturer directions.
Glass Cookware Brands
Luminarc (glass ceramic)
Visions (glass ceramic)
Glass Bakeware Brands
Anchor Hocking (soda lime glass)
Arcuisine by International Cookware (borosilicate glass)
Corningware (glass ceramic). Not all Corningware is glass ceramic. Much of it is stoneware.
Libbey (soda lime glass)
Pyrex (soda-lime glass)
Simax Glassware (borosilicate glass)
Cast iron is made with a blend of iron and steel and cast in a sand mold. While there may be other proprietary ingredients added, lead and cadmium are not found in untreated cast iron. Iron is known to leach into food in significant amounts, often increasing with acidic foods and longer cooking duration. A study by the American Dietetic Foundation found that iron content in spaghetti sauce increased by 945% while that in cornbread increased 28%. For many, the addition of iron to food is viewed as a health benefit because iron deficiency is not uncommon in the U.S. Read more here about how much iron is recommended. Those with a known excess of iron may need to avoid cooking with cast iron.
Cast Iron needs to be regularly seasoned with oil to maintain a relatively non-stick finish and protect against rust. This raises questions about what type of oil to use and if using less-healthy oils creates a risk of its own. Some brands sell cookware pre-seasoned with oil. The types of oil vary by brand with some using healthier oils than others. Since the oil used for pre-seasoning is a small amount and a one-time application, I am more concerned about what oil is used to continually maintain the utensils over time. Some argue that high-smoke point oils are best because when oils are heated above their smoke point, they degrade and give off byproducts that are thought to be carcinogenic. Coconut, avocado, and rice bran oil have high-smoke points. Flaxseed oil is sometimes used because it is a drying oil and creates a durable finish but it has a low smoke point and can become rancid over time.
Beware, if a cast iron product does not need to be seasoned it likely has a non-stick coating. Keep reading to understand concerns about non-stick coatings.
Cast Iron Cookware Brands:
Lodge Seasoned Cast Iron (preseasoned with soybean oil)
Field Company (preseasoned with organic grapeseed oil)
Finex (preseasoned with organic, non-GMO, flaxseed oil)
Cast Iron Bakeware Brands:
Lodge Cast Iron Muffin Pans (preseasoned with soybean oil)
Carbon steel is similar to cast iron except is has a slightly higher iron content. Carbon steel typically is comprised of about 99% iron and 1% steel, while cast iron typically has 97-98% iron and 2-3% steel. The different composition allows carbon steel to be lighter than cast iron. It also needs to be regularly seasoned with oil.
If a carbon steel product does not need to be seasoned it likely has a non-stick coating. Keep reading to understand concerns about non-stick coatings.
Carbon Steel Cookware Brands:
Lodge Carbon Steel (preseasoned with soybean oil)
Matfer Bourgeat (not preseasoned)
US-ION Wrought Iron (preseasoned with rice bran oil)
Stainless steel can be a safe type of cookware if you use it under certain conditions. Stainless steel is known to leach nickel and chromium into food. Nickel is an essential micronutrient for humans but too much can result in the development of dermatitis. Chromium, a trace mineral in the human diet, is less of a health concern than nickel but can also cause dermatitis. Leaching can occur at different levels depending on the acidity of the food being cooked, the amount of time the food is in contact with the cookware and the age of the cookware.1 Studies show that the amount of nickel and chromium that leaches into food is generally below recommended limits. Stainless steel is exempt from California Proposition 65 testing because OEHHA has concluded exposure from metal alloys to be minimal and below thresholds required for warnings.2
However, if you have a known or suspected nickel or chromium sensitivity it may be best to avoid all stainless steel.
You can follow these steps to minimize nickel and chromium exposure:
- Avoid cooking highly acidic foods for long cooking durations. (consider cooking chili or tomato sauce in a glass stock pot.)
- Wash new stainless steel before use and follow this process before using: Cook a solution of 50% vinegar and 50% water for a 2 hour period and discard the solution. Repeat this process 6 times.3 Studies show that stainless steel leaches significantly more nickel and chromium when it is new and levels off after following this process.4
- Consider products that use 430 grade stainless steel (18/0) which contains only trace amounts of nickel. The tradeoff is 430 stainless steel has a little less stain and corrosion resistance than stainless steel made with nickel and requires a little extra care. Be sure to follow manufacturer directions for use and maintenance. Also, make sure that the inner layer that touches the food is 430 steel. Some products claim to be made of 430 steel but only use it on the outer layer that touches the stove so that it can be used with induction cooktops.
Stainless steel is not considered a good conductor of heat so many stainless steel pots and pans have a core layer of aluminum or copper. This means that a layer of aluminum or copper is sandwiched between layers of stainless steel and do not come in contact with food. However, if you have a pot or pan with a scratch deep enough to expose the core, you should replace it out of caution. One manufacturer confirmed their top layer of steel is .015” thick. That is about the thickness of an average fingernail. It’s not very thick, but it is thick enough that you would be able to feel a groove if you ran your finger over it. If the core is copper you would be able to see the core if exposed through a scratch. Keep in mind though, that leaching is partly dependent of the surface area of the material. A very small amount of the core material would be exposed from a deep scratch, limiting the amount of leaching.
Make sure you are buying uncoated stainless steel. Some of these brands also sell non-stick coated products.
Stainless Steel Cookware Brands:
All Clad D3 (430 outer layer, aluminum core, 304 inner layer)
Cutco (430 outer layer, aluminum core, 304 inner layer)
Homi Chef (430 inner and outer layer and aluminum core)
Made In uncoated stainless (430 outer layer, aluminum core, 304 inner layer)
Nöni (solid ferritic stainless steel)
Stainless Steel Bakeware Brands:
All Clad D3 (18/10 stainless steel with aluminum core)
HKJ Chef (18/10 stainless steel)
This is the only ceramic cookware I recommend. Xtrema pots and pans are 100% ceramic, made only from natural minerals, clay and water. No metals are added as ingredients in this ceramic cookware. Because lead is everywhere in the environment and any raw material is likely to have some degree of lead contamination, it is possible that trace amounts could be present. However, every shipment is tested by government-regulated laboratories to ensure that lead, cadmium and other heavy metals do not leach into food. All testing results, which meet California Proposition 65 limits are posted on their website.
I recommend Xtrema because of the company’s transparency and commitment to producing products that are healthy for humans and for the environment. The extremely hard ceramic cooking surface can’t be scratched by metal utensils or steel wool and doesn’t wear off. NOTE: This cookware is fairly heavy and comparable to the weight of cast iron. It is not entirely non-stick but is fairly easy to clean.
This is a particularly challenging category to evaluate because enamels differ in how they are formulated, applied and fired. Most companies consider their formulas and processes to be proprietary and do not disclose them. Porcelain enamel cookware is made primarily of silica sand, soda ash borax and cobalt oxide that are melted together, ground into a powder, then applied to metal cookware and fired at high temperatures. Metals such as cobalt, antimony, arsenic or nickel may be added to improve adherence to the metal base. Cadmium is sometimes used to make bright exterior colors such as red, yellow and orange. Additional substances can be added for functionality including Teflon.
There is little research available on migration of heavy metals from porcelain enamel. Additionally, California Proposition 65 only sets migration limits for lead and cadmium in cookware so it doesn’t tell you about levels of other heavy metals or toxicants.
In 2018, the International Organization for Standardization (ISO) established a new standard for vitreous and porcelain enamels that sets migration limits for 16 heavy metals. The standard was set because of evidence of the presence of metals including aluminum, lead, cadmium, cobalt and nickel. The German Federal Institute for Risk Assessment studied enameled grill grates and found high levels of aluminum, antimony, arsenic and nickel.5 The new ISO standard is voluntary, so manufacturers are not required to meet it, but it will be helpful to identify if there are safer porcelain enameled products. I have not yet found any brands that meet the new standard but if I find any particular brands, I will identify them here.
Porcelain Enamel Brands:
Le Creuset Enamel Cast Iron and Enamel on Steel
Lodge Enameled Cast Iron
Staub Cast Iron
Like porcelain enamel, ceramic stoneware is hard to evaluate because glazes differ in how they are formulated, applied and fired. Unlike porcelain enamel, metals are not needed to adhere ceramic glaze to its base. However, they may include other additives. For example, formulas may include titanium dioxide to make white interior glazes or aluminum oxide to stiffen the glaze.
Manufacturers that do not add lead or cadmium as an ingredient to their products and provide evidence that they meet California Proposition 65 migration levels are less of a concern, but risks remain about other unknown and untested substances.
Be particularly cautious of stoneware that is not made by a reputable company. A study of ceramics from Nigeria found high levels of leaching lead, cadmium, arsenic, and chromium.
Ceramic Stoneware Brands:
Le Creuset Stoneware
Anodizing is an electrochemical process that converts the metal into a corrosion-resistant finish. This keeps the aluminum from leaching but the finish may degrade over time. Unfortunately, I was not able to find any research that measures leaching from anodized aluminum. All studies found are on untreated aluminum. Also, California Proposition 65 does not require testing for aluminum. Aluminum cookware that is anodized should minimize leaching but without evidence I don’t recommend it.
Silicones are considered by some health organizations to be safe. Health Canada states, “There are no known health hazards associated with use of silicone cookware. Silicone rubber does not react with food or beverages or produce any hazardous fumes.”6
However, some studies are finding that silicones are not completely insert and can release certain toxic substances at low level. Studies are still limited and most focus on a type of siloxane group, cyclic volatile methyl siloxanes (cVMS), which are by-products of silicone manufacturing. The health effects of cVMS are debated but in 2018 the European Chemicals Agency added 3 (D4, D5, and D6) to their Candidate List of substances that may have serious effects on human health and the environment.
Some studies are finding that silicone bakeware can leach cVMS into food, particularly at high temperature (above 300°) and into high fat food. For example, migration into meatloaf was higher than into cake.7,8 Greater migration was found in new, unwashed molds.
Silicones, like plastics, can include a mix of chemical additives, fillers, and raw material impurities. There are few studies that focus on the migration or health effects of these potentially harmful ingredients. You can read more here about the toxicity of silicone.
Non-stick Cookware with Ceramic Coating
Many new, non-stick cookware products made with ceramic coatings claim they are non-toxic and a safer alternative to non-stick cookware with PTFE or PFOA coatings. This type of cookware is unproven as a truly safe alternative and there are multiple areas of concern.
Ceramic or “sol-gel” coatings usually contain ceramic nanoparticles that are applied in a thin coat to the surface of the cookware.9 Some use titanium dioxide nanoparticles which according to this study migrate into food, particularly after the coating is scratched from normal use. Chronic exposure to titanium dioxide nanoparticles has been linked to immune disruption and precancerous lesions in the gut.10 The use of nanoparticles in food contact materials is not yet well studied and more research is needed.
According to a major supplier of all types of coatings, the best ceramic coatings last just 15% as long as PTFE-based coatings.11 Where does the coating go? I think it’s safe to assume that the coating ends up in your food.
Ceramic coating formulations can be combined with epoxies, acrylics, or alkyds to give them additional functionality.12 Many manufactures will not release the ingredients in their coatings because they consider them proprietary. Some hybrid ceramic coatings also contain PTFE.
Cookware for noncommercial use is exempt from FDA regulation. That means that one can’t assume that ingredients in cookware that come in contact with food have been tested and proven safe.13, 14 The FDA does stipulate that if non-stick coatings are found to “adulterate food with unsafe substances” immediate action will be taken. That’s too little too late. While California Proposition 65 provides stringent regulations for lead and cadmium in cookware it does not currently regulate nanoparticles, PTFE, aluminum, non- airborne titanium dioxide, nor other cookware ingredients of concern.15
It’s possible that there are some safer options within this category and I will update the guide accordingly should I learn of them.
Non-Stick Ceramic Coating Brands:
Our Place Always Pan
Zwilling J Henckels Spirit Cookware
Non-Stick Cookware with PTFE Coating
PTFE is one of 3000 poly- and perfluoroalkyl substances (PFAS) used in consumer products. PFAS chemicals are known as “forever chemicals” because they are persistent in the environment and in our bodies. Most people looking to avoid toxins know not to use non-stick pots and pans because coatings with PTFE, when heated to high temperatures, can release fumes that coat the lungs and can cause fluoropolymer fever, also known as Teflon flu. PFOA, another PFAS chemical, was used in the past to manufacture PTFE and was sometimes found as a contaminant in products made with the chemical. PFOA is considered a toxic substance by the EPA and has been linked to adverse effects including cancer, birth defects and liver damage. Fortunately, most reputable companies no longer manufacture PTFE using PFOA.
However, new studies by the FDA have found that the short chain PFAS chemicals used to replace PFOA are much more toxic than previously thought.16 Additionally, PTFE which is thought by some health experts to be harmless because it is inert, is considered a moderate health concern by the Environmental Working Group (EWG) because it hasn’t been studied.
Any pan that claims to have a non-stick coating is likely either PTFE based or ceramic based and should be avoided.
Non-Stick Cookware with PTFE Coating Brands:
Calphalon Hard-Anodized Aluminum Nonstick
Made in Non-Stick Cookware
Most aluminum cookware is either anodized or coated with a non-stick surface. It is well established that untreated aluminum leaches into food. One study found aluminum leaching during conditions comparable to cooking acidic foods for long periods that were 6 times the recommended level. Aluminum is the third most prevalent element in the earth’s crust. It is not an essential element for humans but because of its ubiquity it accumulates in the human body mainly through food. It’s important to eliminate unnecessary sources. Aluminum has an effect on many biological processes and is linked to many adverse health effects including neurotoxicity. Though hotly debated, high levels of aluminum have been linked to breast cancer and Alzheimer’s disease.17
Most copper cookware is lined with stainless steel. Copper cookware lined with stainless steel should have the same safety profile as stainless steel cookware.
The FDA warns against cooking with unlined copper. Copper is an essential nutrient for the human body but too much can be toxic. Excess copper can cause nausea and vomiting and very high doses can cause liver and kidney damage.18
My Thoughts on XRF Testing
There are bloggers who use XRF equipment to test for lead in consumer products including cookware. XRF instruments test for lead content, while California Proposition 65 and federal regulations (in the U.S., Canada, EU, and others) use laboratory methods that test for leaching. Leach testing uses acidic solutions to see if any heavy metals that may be added or present in raw materials are extractable, meaning they can leach out of cookware and into food. Some bloggers have written about lead content (which says nothing about leaching) in Xtrema, Visions glass cookware, porcelain enameled cookware and others. I personally base my recommendations on leach testing and specifically look for California Prop 65 because it has the most stringent lead leaching limits. Because there is no safe level of lead, I applaud these bloggers efforts and desire to avoid out of caution anything with lead content whether or not it leaches out into food. But, in this case there is an abundance of independent research that shows Xtrema and Visions do not leach into food. And there are few safe alternatives. You could choose to use stainless steel and cast iron exclusively but you would be exposed to greater amounts of nickel and iron. If that seems like a better alternative for you, that’s fine. My preference is to rotate a larger number of cookware materials to limit any one exposure. I have laid out the facts so that you can make the choice that is right for you and your family.
A final note… I sent my own Xtrema pot, which I have used for years and regularly subjected to steel wool scrubbers and dishwashing, to an independent lab to be tested for lead because I have read (unsubstantiated) claims that leaching from Xtrema increases over time even if it doesn’t leach at the time of testing. Even though this was tested at a lab I’m not claiming the result is significant because it is just one sample. I did it simply to satisfy my own curiosity. The results below show no detectable levels of lead.
Here is what I use in my own home:
Xtrema large skillet. This is a workhorse in my kitchen.
Xtrema small and large saucepans. I use these for pasta and sauces, with the exception of acidic foods.
Visions ceramic glass Dutch oven. This replaced the Le Creuset I used for years. I use this to make highly acidic foods that require long cooking times like chili and tomato sauce. I have to admit it makes me a little nervous cooking with glass and I worry about shattering but I’m getting used to it.
Cast iron muffin pans. These replaced my silicone muffin pans that I had used for years.
Borosilicate glass loaf pan. I use these for meatloaf and breads.
Pyrex soda lime glass baking pans.
Stainless Steel cookie trays and sheet pans
430 Stainless Steel small skillet. This is nickel-free stainless steel. I use this small skillet for eggs.
A reader recently asked me to look into a playground mulch product to determine its toxicity. I’d like to share the results with you because I think it will be helpful to anyone trying to decide what material to use for their outdoor playsets but also because it is a good example of how important it is to look beyond marketing claims and understand what regulations do and do not address.
The product is described as a virgin rubber mulch product that contains no phthalates, heavy metals or VOCs. It meets California indoor air standards. The company distinguishes its product from tire-derived rubber (TDR) that is often used on playgrounds and turf fields and has been found to emit dangerous levels of chemicals as well lead.
The company is unable to provide a Safety Data Sheet (SDS) because it is made from trimmings and unused material from children’s safety tile flooring. Their product is a combination of products from many different manufacturers.
They were able to provide testing that showed that the test sample had:
- No detectable levels of phthalates. This is not surprising because while phthalates were widely used in flooring, manufacturers have been eliminating them.
- Lead detected at 3ppm which is well below California’s restriction of <80ppm for playground mulch but it is not zero.
There was no testing done for Total VOCs (TVOC) but if the product meets California Section 01350 it must have TVOC less than or equal to 0.5mg/m3.
Here are my concerns that this product, while perhaps not as bad a tire-derived rubber, has some of the same issues:
- A 2010 study by California’s Department of Public Health (CDPH) titled Tire-Derived Rubber (TDR) Flooring Chemical Emissions Study found:
- Both TDR and new rubber (NR) flooring products still emit a myriad of VOC chemicals, and their release is not uniform among the different products. A minority of products released excessive amounts of chemicals; and
- Xylene, butylated hydroxytoluene, ethylbenzene, toluene, formaldehyde and acetaldehyde were found in a range of products. Benzene and carbon disulfide were above the health threshold in one or two samples… Some of the identified chemicals do not yet have health-based standards, making their health impacts difficult to assess.
Even if the product meets California Standards, it is likely emitting at least some of the above chemicals, just at a level that meets the standard. Because this will be outdoors, the risk is somewhat mitigated (although it’s still not good for the environment!).
There is a level of lead, it is simply below the standard allowed. California has a restriction of 80ppm for rubber mulch used on playgrounds. While no level of lead is safe, some soil can contain levels of lead that are higher. The EPA considers 400ppm in soil acceptable. But, again, no level is safe.
The limitations of the testing provided is that it is unclear how much of the finished product is actually tested. Because the product is a combination of materials from many manufacturers, it is not known if the test covers products from every supplier or is it a test of just one or a few. Given the potential problems with new virgin rubber it is a concern.
Overall, this product is likely much less toxic than tire-derived rubber mulch. It does, however, have low levels of lead and VOCs. The VOCs will be mitigated because it will be outdoors. While this is a less toxic product, I would still opt for natural, untreated wood mulch.
Take a look at my latest Sunscreen Product Review.
Last week I wrote about the toxicity of silicone and revealed that while research is still limited, studies show that silicone does leach potentially harmful chemicals into food, particularly at temperatures above 300°. Following the precautionary principle, I recommend avoiding cooking and baking with silicone.
What Do I Buy to Replace my Silicone Bakeware?
I have to admit, I will miss my silicone muffin pan. Silicone has become so popular because it is non-stick and is easy to clean. The safer options aren’t non-stick but that’s a tradeoff I’m willing to make. Here are some options:
Unless you are sensitive to nickel, stainless steel is a safe alternative. Just make sure the stainless steel is not coated or treated. You can find stainless steel cookie sheets, muffin pans, and baking pans.
18/0 stainless steel does not contain nickel and may be an acceptable option for those sensitive to nickel. If you have a nickel allergy, check with your doctor before using. Here is a cookie sheet made from 18/0 stainless steel with no coating.
Cast iron is generally a safe choice. Cast iron will release iron which has many important functions in the human body. You can, however, get too much iron. If you use cast iron, you may want to rotate it with other types of cookware to avoid getting too much iron. Here is a Lodge cast iron muffin pan.
Are Oven-Safe Paper Baking Products Safe to Use?
Paper is not inherently non-stick so most paper bakeware is coated. Parchment paper is usually coated with silicone or Quinlon, which is a chemical containing the heavy metal chromium. I have not found any studies that assess the migration of Quinlon into food so out of caution I would avoid it.
Oven-safe paper bakeware is usually lined with silicone or plastic. While I wasn’t able to find any studies that looked specifically at leaching from paper bakeware, I see no reason to assume it would be any safer than silicone bakeware. Out of caution, I would avoid it too. Sorry!
Should I use my Silicone Bakeware?
This is a personal consideration. The research on silicone bakeware is limited but there is evidence that leaching into food does occur. The only piece of silicone bakeware that I have is a muffin pan and I will be replacing that with a Lodge cast iron pan.
Another consideration is how often you use your silicone bakeware. If you are regularly using it I would recommend replacing it with a safer option. If you use one piece very infrequently the overall exposure is much less and you might consider continuing to use it. Find the balance that works for you.
Silicones are made from silicon, a naturally-occurring element that is abundant in sand. However, in order to make silicon available for industrial processes, it’s heated to very high temperatures and reacted with fossil-fuel derived hydrocarbons.1 This may explain why some people who are sensitive to petrochemicals may react to silicones.
In order to make silicones, silicon is turned into siloxane, through an industrial process. There are a number of different siloxanes. Siloxanes are then bound together into silicones.
Is Silicone Safe?
Silicones are generally considered safe. Health Canada states, “There are no known health hazards associated with use of silicone cookware. Silicone rubber does not react with food or beverages, or produce any hazardous fumes.”2
However, some studies are finding that silicones are not completely insert and can release certain toxic substances at low level. Studies are still limited and most focus on a type of siloxane group, cyclic volatile methyl siloxanes (cVMS), which are by-products of silicone manufacturing. The health effects of cVMS are debated but in 2018 the European Chemicals Agency added 3 cVMS (D4, D5, and D6) to their Candidate List of substances that may have serious effects on human health and the environment.
There are few studies that focus on the effects of chemical additives, raw material impurities or fillers that may be present in various silicone products.
Does Silicone Leach into Food and Drink?
Some studies are finding that silicone bakeware can leach into food, particularly at high temperature (above 300°) and into high fat food. For example, migration into meatloaf was higher than into cake.3,4 Greater migration was found in new, unwashed molds.
One study found that silicone baby bottle nipples do not leach VMS into milk or infant formula after 6 hours.5. However, a particularly alarming study from 2012 of silicone baby bottles found the presence of phthalates and aldehydes as well as substances related to printing ink.6 A 2016 study similarly found phthalate migrations from silicone baby bottles.7 The studies did not assess the migration levels and associated health risks. Further research is needed.
Do Silicones Offgas?
Siloxanes can become gaseous when heated. In one study, 4 of 14 silicone baking molds exceeded Germany’s indoor guide level for cVMS but the health hazard guide level was not exceeded.8
Additionally, a possible oxidation product is formaldehyde.9 Studies of industrial-use silicone have found formaldehyde release at very high temperatures but it is not clear if formaldehyde also releases from silicone consumer products when heated.
Do All Silicones Have the Same Level of Toxicity?
Silicones, like plastics, can include a mix of chemical additives, fillers, and raw material impurities. In general, however, silicones have fewer chemical additives than plastics.
Food-grade silicones that are regulated by the FDA should not contain fillers. Silicone should not change color when it is twisted. If you twist or pinch the silicone and white shows through, the product contains a filler. Also, silicone should not crack or lose elasticity. These conditions indicate the inclusion of fillers in the silicone.
Not all silicone is the same and it is not possible without testing to determine exactly what is in any silicone product. There are hundreds of silicones with hundreds of different formulas. Some, like colorful cookware, may contain various fillers and contaminants that are completely unknown to consumers.
The Bottom Line
There is enough scientific evidence to suggest that silicone is not the totally safe and natural material that some marketers claim it to be. But it is generally safe under many conditions and a safer alternative to most plastics.
Here are some guidelines to safely use silicone products.
- Do not heat silicone products above 300°.
- Always wash silicone products before use with food or beverages.
- If using silicone baby bottles or nipples, make sure they are phthalate-free.*
- Choose 100% pure food-grade or medical-grade silicone.
- Silicone that is not heated and does not come in contact with food, such as lids, gaskets, bibs, and placemats likely pose no health risk.
*I will look further into the safest choices for baby bottles and nipples.
- Ruediger Helling, Anja Mieth, Stefan Altmann, Thomas Joachim Simat. Determination of the overall migration from silicone baking moulds into simulants and food using 1H-NMR techniques. Food Additives and Contaminants, 2009, 26 (03), pp.395-407. 10.1080/02652030802520852 . hal-00577342
- Helling R, Kutschbach K, Joachim Simat T. Migration behaviour of silicone moulds in contact with different foodstuffs.Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2010;27(3):396-405. doi:10.1080/19440040903341869
- Zhang K, Wong JW, Begley TH, Hayward DG, Limm W. Determination of siloxanes in silicone products and potential migration to milk, formula and liquid simulants. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2012;29(8):1311-1321. doi:10.1080/19440049.2012.684891
- Simoneau, Catherine & Van den Eede, Liza & Valzacchi, Sandro. (2012). Identification and quantification of migration of chemicals from plastics baby bottles used as substitutes for polycarbonate. Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment. 29. 469-80. 10.1080/19440049.2011.644588.
- Ksenia Groh, Health Risks of BPA-Free Baby Bottles. Food Packaging Forum, Sept. 9, 2016.
- Hermann Fromme, Matthias Witte, Ludwig Fembacher, Ludwig Gruber, Tanja Hagl, Sonja Smolic, Dominik Fiedler, Marina Sysoltseva, Wolfgang Schober. Siloxane in baking moulds, emission to indoor air and migration to food during baking with an electric oven. Environment International, 2019, 126, pp.145-151. 1016/j.envint.2019.01.081
- Birgit Geueke, Dossier – Silicones. Food Packaging Forum. May, 2015, DOI: 10.5281/zenodo.33522
Polyethylene is the most widely produced commodity plastic and it is primarily used for packaging. Some common forms of polyethylene are:
LDPE is a flexible material that is used in food storage bags, trash and grocery bags, toys, and housewares. The plastic recycling code of LDPE is #4.1
HDPE has high strength and moderate stiffness. It has a higher melting point than LDPE and can be sterilized. It is used in bottles for milk and household cleaners, food storage bags, grocery bags, appliance housing and toys. The plastic recycling code of HDPE is #2.2
Is Polyethylene Safe?
Polyethylene is considered one of the safest plastics.
According to its Safety Data Sheet, polyethylene has not been found to be carcinogenic by several safety organizations including the International Agency for Research on Cancer (IARC) and the Occupational Safety and Health Administration (OSHA).
Not all polyethylene, however, is created equal. Plastics are often made with fillers, plasticizers, and additives to enhance their functionality.3 A single plastic product can contain dozens of added chemicals. Polyethylene is less likely than many other plastics to contain fillers, plasticizers and additives but they may still be present. Unfortunately, without better disclosure from manufactures about the content of specific plastic materials we can only speak about toxicity and safety in general terms.
Does Polyethylene Offgas?
Polyethylene does offgas but generally at a much lower rate than more toxic plastics such as PVC and polystyrene.4
Does Polyethylene Leach into Food and Drink?
While polyethylene is relatively stable, and it is generally considered a safer plastic for food and drink, it has also been shown to leach plastic additives. In one study, pure polyethylene resin did not leach any endocrine disrupting chemicals but common food containers made with polyethylene did leach.5 Leaching from plastic food containers is increased with heat, duration of contact, and acidity of the food or drink. So, consider how the item is being used and how you will be exposed to it. For example, a food storage bad made of polyethylene that is used to carry a snack of pretzels is less likely to leach than the same bag used to store hot tomato soup.
Avoiding any plastic is ideal because it not only poses risk to human health but it is harmful to the environment. But, if you must use products made with polyethylene, the risk of exposure is probably low.
1The Editors of Encyclopaedia Britannica. “Polyethylene.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 15 Nov. 2019, www.britannica.com/science/polyethylene.
2 The Editors of Encyclopaedia Britannica. “Polyethylene.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 15 Nov. 2019, www.britannica.com/science/polyethylen
3John N. Hahladakis, Costas A. Velis, Roland Weber, Eleni Iacovidou, Phil Purnell. An overview of chemical additives present in plastics: Migration, release, fate and environmental impact during their use, disposal and recycling. Journal of Hazardous Materials. 2018; volume 344; pages 179-199. License.
4Even M, Girard M, Rich A, Hutzler C and Luch A (2019) Emissions of VOCs From Polymer-Based Consumer Products: From Emission Data of Real Samples to the Assessment of Inhalation Exposure. Front. Public Health 7:202. doi: 10.3389/fpubh.2019.00202
5John N. Hahladakis, Costas A. Velis, Roland Weber, Eleni Iacovidou, Phil Purnell. An overview of chemical additives present in plastics: Migration, release, fate and environmental impact during their use, disposal and recycling. Journal of Hazardous Materials. 2018; volume 344; pages 179-199. License.
Polypropylene is the second-most widely produced commodity plastic (after polyethylene) and it is often used in packaging and labeling.
Polypropylene is very similar to polyethylene but has greater resistance to heat, which is why it is often used for food packaging and food storage bags and containers.
Is Polypropylene Safe?
Polypropylene is considered one of the safest plastics.
According to its Safety Data Sheet, polypropylene has not been found to be carcinogenic by several safety organizations including the International Agency for Research on Cancer (IARC) and the Occupational Safety and Health Administration (OSHA).
Not all polypropylene, however, is created equal. Plastics are often made with fillers, plasticizers, and additives to enhance their functionality.1. A single plastic product can contain dozens of added chemicals. Polypropylene is less likely than many other plastics to contain fillers, plasticizers and additives but they may still be present. Unfortunately, without better disclosure from manufactures about the content of specific plastic materials we can only speak about toxicity and safety in general terms.
Does Polypropylene Offgas?
Polypropylene, sometimes referred to as Olefin, does offgas but generally at a much lower rate than more toxic plastics such as PVC and polystyrene.2
It is often used to make medical equipment and to store museum collections because of its relatively low level of emissions.
Does Polypropylene Leach into Food and Drink?
While polypropylene is relatively stable, and it is generally considered a safer plastic for food and drink, it has also been shown to leach plastic additives. In one study, pure polypropylene resin did not leach any endocrine disrupting chemicals but common food containers made with polypropylene did.3 Leaching from plastic food containers is increased with heat, duration of contact, and acidity of the food or drink. So, consider how the item is being used and how you will be exposed to it. For example, a water bottle made of polypropylene that has only brief contact with the water is less likely to leach than a container used to store hot tomato soup.
Avoiding any plastic is ideal because it not only poses risk to human health but it is harmful to the environment. But, if you must use products made with polypropylene, the risk of exposure is probably low.
1John N. Hahladakis, Costas A. Velis, Roland Weber, Eleni Iacovidou, Phil Purnell. An overview of chemical additives present in plastics: Migration, release, fate and environmental impact during their use, disposal and recycling. Journal of Hazardous Materials. 2018; volume 344; pages 179-199. License.
2Even M, Girard M, Rich A, Hutzler C and Luch A (2019) Emissions of VOCs From Polymer-Based Consumer Products: From Emission Data of Real Samples to the Assessment of Inhalation Exposure. Front. Public Health 7:202. doi: 10.3389/fpubh.2019.00202
3John N. Hahladakis, Costas A. Velis, Roland Weber, Eleni Iacovidou, Phil Purnell. An overview of chemical additives present in plastics: Migration, release, fate and environmental impact during their use, disposal and recycling. Journal of Hazardous Materials. 2018; volume 344; pages 179-199. License.; McDonald GR, Hudson AL, Dunn SM, et al. Bioactive contaminants leach from disposable laboratory plasticware. Science. 2008;322(5903):917. doi:10.1126/science.1162395
I regularly see healthy-living experts touting the use of houseplants to clean indoor air. Unfortunately, most research does not support this claim. I have a lot of plants in my home because I appreciate their aesthetic value. I hope that they contribute some small benefit to my home’s air quality but I don’t rely on them to do the job. Let’s look at the facts to see if there are benefits and perhaps even risks to filling your home with potted plants.
The idea that plants are effective at removing VOCs from indoor air stems from a 1989 NASA study that tested different types of houseplants in a sealed chamber. The testing methodology was designed to simulate the small, air-tight environment of a space capsule. The study found that under these conditions, some plant types were particularly effective at removing VOCs including formaldehyde and benzene.
Subsequent studies have shown that the results do not translate to a typical house. The size of a house and the amount of ventilation play a big role in the how much impact a plant will have on air quality. A 1991 EPA review of the NASA study determined that a typical house would require 680 plants to yield the same results. A 2019 review of 30 years of research determined that it would take 10 to 1000 plants per square meter of floor space to provide more effective cleaning power than opening a couple of windows.
If you do choose to have houseplants in your home make sure you are not adding VOC pollution.
- Use untreated metal, clay or ceramic pots.
One study found that 11 different volatile organic chemicals (VOCs) were emitted into the air from plastic pots.
- Buy organic plants, grown without pesticides.
Pesticides used in the plant production process can have volatile emissions.
- Make sure your plants are not a source of mold.
Regularly check the soil for signs of mold.
If you see a recommendation to use houseplants to clean your air make sure you understand the source behind the recommendation and determine if this is new data that factors in a typical home environment or if it is simply advice based on outdated research.
A reader submitted a question to Toxic Free Q&A about how to minimize lingering odor from zero-VOC paint. Andy Pace, from The Green Design Center, wrote in with a comment that was so helpful I want to share it with everyone.
According to Andy, “Lingering odor is almost always caused by moisture trapped in the coatings. As the moisture comes out, it carries with it the chemical footprint of where it was, which usually means, a distinct aroma of resins and solvents. It’s true that the BM Regal is zero-VOC, but the biggest reason why the Behr paint is problematic may have to do with the color. Most people apply dark colors way too heavy…trying to get a nice thick coat so it appears to cover well. This is counterproductive. Water based paint needs to go on very thin in order to cure properly. Thick coats will cause lingering odors and a softer film. So, dark colors will be more prone to long lasting odors than will off white colors, no matter the product line. At this point, adding another layer or two of product will only prolong the situation. Get a large fan and direct it towards the offending surface. This will help wick away the moisture. Use a dehumidifier in that room. As a last resort, wipe the surface gently with isopropyl alcohol (or a cheap vodka) and just let the alcohol evaporate naturally. As it evaporates, it will pull moisture out of the paint.”
This advice is helpful whether you have a room you have already painted or if you plan to paint in the future.
Tips for Minimizing Off-Gassing from Paint
- Start with zero-VOC paints that are also free of solvents, biocides or fungicides. Recommended brands are AFM Safecoat and ECOS.
- Apply water-based paint in very thin coats.
- Allow 2-4 hours for paint to dry between coats.
- Water-based paints cure from the outside-in, so the surface will feel dry first. Make sure you allow enough time for each coat to dry before applying another coat.
- Use a large fan to help wick away moisture.
- Run a dehumidifier in the room being painted.
- If necessary, wipe the surface gently with isopropyl alcohol and let it evaporate.
I highly recommend The Green Design Center if you are looking for non-toxic building supplies. Andy and his team also specialize in helping people with MCS find building supplies that are well-tolerated. Check out his podcast too!
Question from Marilyn
I’m planning to redo a bathroom with an open shower. The contractor tells me it involves some kind of hot tar layer to make the floor water proof before laying tile. Do you know of a non-toxic option that meets California code?
I am not familiar with California code so you will need to work with your contractor on that. I have used Hardibacker Board or another water-resistant cementitious board as an underlayment for the tile. I recommend the book “Prescriptions for a Healthy Home, 3rd edition” for any building or remodel project that you have.