Widely used in moisturizer, makeup, hair products, etc. Can interfere with hormone function and damage the liver. Harmful to fish and other wildlife.
These silicone-based compounds are used in cosmetics to soften, smooth, and moisten. They make hair products dry more quickly and deodorant creams slide on more easily. They are also used extensively in moisturizers and facial treatments. Siloxanes can also be found in medical implants, water-repelling windshield coatings, building sealants and lubricants.
Health and Environmental Hazards
Environment Canada assessments concluded that cyclotetrasiloxane and cylcopentasiloxane — also known as D4 and D5 — are toxic, persistent, and have the potential to bioaccumulate in aquatic organisms. Also, the European Union classifies D4 as a endocrine disruptor, based on evidence that it interferes with human hormone function, and a possible reproductive toxicant that may impair human fertility. In laboratory experiments, exposure to high doses of D5 has been shown to cause uterine tumours and harm to the reproductive and immune systems. D5 can also influence neurotransmitters in the nervous system.
Structurally similar to D4 and D5, cyclohexasiloxane (or D6) is also persistent and has the potential to bioaccumulate. Environment Canada’s assessment of D6 concluded that this third siloxane is not entering the environment in a quantity or concentration that endangers human health or the environment, but noted significant data gaps concerning its toxicity.
Cyclomethicone is a mixture of D4, D5, and D6 siloxanes.
January 2009, Environment Canada and Health Canada proposed to add D4 and D5 siloxanes to the List of Toxic Substances pursuant to the Canadian Environmental Protection Act, 1999 (CEPA), and to develop regulations “to limit the quantity or concentration of D4 and D5 in certain personal care products.”. In addition, under CEPA, anyone proposing a “significant new activity” involving siloxanes must notify the Minister of the Environment. However, there are currently no restrictions on these ingredients in cosmetics.
Polydimethylsiloxane (PDMS) silicone polymers are produced from D4 and contain residual amounts of D4 and D5. Dimethicone is a common PDMS ingredient in cosmetics.