Toxic ingredient to avoid: Siloxanes

Health and environmental hazards of siloxanes

Human health risks and concerns

Siloxanes are regarded as non-toxic to people and the environment. Humans tolerate them well — why they’re used so much in the medical industry. But they may have endocrine disrupting properties and reproductive effects.

People are exposed to siloxanes L2, L4, L5, D3, D4 and dvTMDS.

• Laboratory studies have found that L2 affects the liver, testes, and lungs. L4 also affects the liver.
• D3 is also associated with effects on the liver. D4 is a suspected endocrine disruptor and reproductive toxin.
• Other siloxanes may also have endocrine disrupting and other toxic effects.

Environmental risks and concerns

Many siloxanes are persistent in the environment. These are classified as “persistent-bioaccumulative-toxic,” i.e., they build up in the environment. One of the most used siloxane is polydimethylsiloxane, a.k.a. dimethicone and PDMS. This ingredient is likely to bioaccumulate in the tissues of organisms. It’s also likely to persist in the environment and be toxic to aquatic life. Cyclopentasiloxane (D4) is generally safe for human use. But it may have a negative impact on the environment. It’s a stable and nonreactive chemical, so can take years to decompose. It may evaporate into the air or enter waterways through drainage systems when rinsed off skin or hair. The Government of Canada reports that D4 doesn’t enter the environment in conditions or quantities that make it harmful. But some scientists consider it toxic to aquatic life.

Regulatory status of siloxanes

Current regulatory status of siloxanes in Canada

The Government of Canada classified the ecological hazard and exposure potentials of siloxanes, including D3, dvTMDS, L2, L4 and L5, using the ecological risk classification of organic substances approach. It concluded that these substances aren’t harmful to human health and don’t enter the environment at harmful levels. In Canada, D3 isn’t a permitted food additive.

Current regulatory status of siloxanes in the European Union

In 2020, the EU restricted D4 and D5 in wash-off cosmetic products like soaps, shampoos and hair conditioners. The Norwegian Environment Agency did comprehensive research on persistence and bioaccumulation risks of linear siloxanes( L2, L3, L4 and L5). This has led to increased scrutiny by the EU.

In 2024, the European Commission, the EU’s executive arm, adopted restrictions on cyclosiloxanes D4, D5 and D6. These take effect in June 2026. They stipulate that D4, D5 and D6 shall not be placed on the market as a substance on its own, in mixtures or as a constituent in other substances in a concentration equal to or greater than 0.1 per cent by weight. D4, D5 and D6 shall not be used as a solvent for dry cleaning textiles, leather and fur after June 6, 2026.

Function of siloxanes

Cyclopentasiloxane (D5) a.k.a. decamethylcyclopentasiloxane, is a liquid found in many skin care and cosmetic products. It works as a skin-softening and smoothing emollient. It gives products a silky feel called “slip.” D5 coats skin and hair, making it effective as a detangler and anti-frizz product. Water resistant D5 is also used as a sealant and as a coating for windshields. D3 is found in body makeup, face cream, fragrance and diaper cream.

In Canada, L2 siloxanes are used as solvents in cosmetics, body lotion, nail polish drying drops, electronics, medical devices and anti-freeze and de-icing products. L5 is used in paints. D3 is used as a solvent and emollient in cosmetics, adhesives and sealants. DvTMDS is used in food packaging materials.

How to avoid siloxanes

What to look for on labels

Analyze labels. Pay special attention to foods, cosmetics and sexual health products. Look for:

• Siloxane, ethicone and silane as suffixes on ingredient names. Examples cyclotetrasiloxane, dimethicone and triethyoxycaprylylsilane.
• Dimethicone (polydimethylsiloxane)
• Decamethylcyclopentasiloxane
• Amodimethicone
• Cyclotetrasiloxane
• Cylcopentasiloxane
• Cyclohexasiloxane
• Cyclomethicone

Avoid cookware and personal care products that contain siloxanes:

• Antifoam FD 62
• DIME
• DC 35A, DC 360
• dimethyl siloxane
• Dow Corning 200
• Dow Corning 561
• Dimethylpolysiloxane
• KO 08
• PMS 1.5

Substitutes

Siloxanes are found in cosmetic and personal care products because there are few alternatives and formulating without them is tricky. Brands offering MADE SAFE certified products suggest alternatives that still have the same silky feel and application without siloxanes. Alternatives in cleaning products include:

• Mineral oils
• Paraffin oils
• Vegetable oils

Alternative methods

Look for independently certified organic products. The certifier’s logo will appear on packaging. Companies like The Soil Association or Ecocert independently verify that a product is organic and mostly prohibits the use of synthetic chemicals.