Dimethyl silicone, most commonly called dimethicone in skincare or polydimethylsiloxane (PDMS) in food labeling, is not considered harmful at the levels people typically encounter. It shows up in cooking oils, fast food fryers, lotions, shampoos, and even medical devices. Regulatory agencies in both Europe and the United States have reviewed it repeatedly and allow its use in all of these contexts.
That said, the answer depends on how you’re exposed to it. Eating trace amounts in fried food is very different from inhaling silicone fumes in an industrial accident. Here’s what the evidence actually shows for each route of exposure.
What Dimethyl Silicone Is
Dimethyl silicone is a synthetic polymer made of repeating units of silicon and oxygen, with methyl groups attached. It’s a clear, odorless liquid that can range from thin and watery to thick and greasy depending on the formulation. Its key property is that it reduces surface tension in liquids, which makes it useful as an anti-foaming agent in food manufacturing and as a skin-smoothing ingredient in cosmetics. You’ll see it listed as dimethicone on personal care products, PDMS or polydimethylsiloxane on industrial labels, and E900 on European food packaging.
Dimethyl Silicone in Food
PDMS is added to cooking oils and deep fryers to prevent dangerous foaming, splashing, and bubbling when food hits extremely hot oil. Fast food chains use it for exactly this reason. Beyond frying oil, it can appear in chewing gum, canned fruits and vegetables, soups and broths, pineapple juice, flavored drinks, jams, confectionery, batters, and even effervescent supplement tablets.
The European Food Safety Authority (EFSA) re-evaluated E900 and set an acceptable daily intake of 17 mg per kilogram of body weight per day. For a 150-pound person, that works out to roughly 1,150 mg daily, a threshold far above what anyone would realistically consume from food. The previous limit, set in 1990, was much lower at 1.5 mg/kg per day, but EFSA raised it after reviewing newer toxicity data and finding no adverse effects in animals at doses up to 1,742 mg/kg per day.
Your body barely absorbs the stuff. In rat studies, animals given a full gram of PDMS in their food excreted the vast majority of it in feces, with only microgram-level traces detectable in urine. Internal organs showed no pathological changes. The compound essentially passes through the digestive tract largely intact.
Dimethyl Silicone on Your Skin
Dimethicone is one of the most common ingredients in moisturizers, primers, hair conditioners, and anti-chafing products. It forms a breathable barrier on the skin’s surface that locks in moisture and gives products a smooth, silky feel.
The Cosmetic Ingredient Review panel, which independently evaluates cosmetic safety, found that dimethicone does not meaningfully penetrate the skin barrier. In one study using radiolabeled dimethicone applied to rats under an occlusive patch for 24 hours, 70% of the dose stayed on the patch materials and 11.4% remained at the application site. None was detected in the blood. Feces and exhaled carbon dioxide captured only 0.01% and 0.001%, respectively.
A separate study on human abdominal skin and vaginal tissue over 96 hours confirmed a very low penetration rate. Researchers specifically tested whether dimethicone disrupts the lipid structure of the outermost skin layer and found that it does not interact with or alter it. This is largely because of the molecule’s size and its extremely low water solubility, both of which make it very unlikely to cross through skin cells into the bloodstream.
The One Exposure Route That Matters
Inhalation is the scenario where silicones have caused real harm, though only in unusual circumstances. In one documented case, 39 workers were accidentally exposed to airborne alkylsiloxanes from a tile-coating product in an industrial setting. Every single person developed a cough. Beyond that, 74% experienced shortness of breath, 66% developed a fever, 51% had rapid breathing, and 38% had an elevated heart rate. Chest pain occurred in 20% of cases. Symptoms appeared within 1 to 12 hours of exposure.
All 39 workers recovered within 72 hours. And importantly, the FDA noted that the toxic effects may have been partly caused by the solvent used to suspend the siloxanes, not the silicones themselves. The quality of evidence for systemic toxicity from this single incident was rated low. Still, it highlights that breathing in concentrated silicone fumes is genuinely dangerous, even if the compound is harmless when eaten or applied to skin.
Do Silicones Build Up in the Body?
This is a common concern, especially among people who use silicone-based skincare daily or eat fast food regularly. The short answer: there is limited evidence of meaningful accumulation. When rats were fed siloxanes and their organs were examined over 24 hours, small amounts were detected in the brain and kidneys, but no organ damage was observed. Cyclic forms of PDMS (a slightly different molecular structure) tended to stay in the bloodstream and partially in the kidneys rather than distributing to other tissues.
For skin application, the near-zero absorption rates make buildup essentially a non-issue. For dietary exposure, the overwhelming majority of ingested PDMS leaves the body in stool. The amounts that do get absorbed are trace-level.
Medical Implants and Injections
Silicone is also widely used in medical devices, from breast implants to lubricant coatings on syringes. The FDA reviewed the biocompatibility literature and found that the most common tissue reaction to implanted silicone is mild local inflammation, reported in 14 animal studies. A foreign body response, where the immune system walls off the implant with scar tissue, appeared in 12 studies. These are standard reactions to almost any implanted material, not unique to silicone.
Five animal studies found that injected silicone oil microdroplets could act as an immune adjuvant, potentially boosting antibody responses to other substances present at the same time. One randomized controlled trial did not replicate this finding. No serious systemic reactions were reported in any animal study involving silicone implants or injections.
The Bottom Line on Daily Exposure
For the ways most people encounter dimethyl silicone, the risk is negligible. It doesn’t penetrate your skin in meaningful amounts. It passes through your gut largely unabsorbed. Regulatory limits for dietary intake are set hundreds of times below the dose that causes any observable effect in animals. The only documented harm in humans came from inhaling concentrated fumes in an industrial accident, a scenario most people will never face. If you’re using a dimethicone moisturizer or eating fries cooked in oil containing PDMS, the evidence consistently points to safety.