Polydimethylsiloxane (PDMS) is a silicon compound most widely used as a silicon-based organic polymer, and is often used in shampoos as dimethicone, which makes hair shiny and slippery, amongst other applications.
This ECETOC report presents a critical evaluation of the toxicity, physico-chemical properties, and environmental fate and effects of linear PDMSs and found there to be no environmental risks.
No environmental risk
According to the report, almost all PDMS discarded ‘down-the-drain’ is expected to be removed during sewage treatment.
“Any PDMS released into the environment will strongly sorb to particulate matter in water and soil. PDMSs are immobile in soil and sediment, but will break down slowly (abiotic) to dimethylsilanediol, which is soluble in water and can biodegrade to carbon dioxide, water and inorganic silicate, as demonstrated in the laboratory,” comments ECETOC.
Due to its molecular size, the researchers say bioconcentration of PDMS is very unlikely. PDMSs are not detected in surface waters, except at low concentrations downstream from wastewater treatment plants.
No health risk
Humans may be exposed to PDMS via dermal contact and oral ingestion. Aerosolised PDMS may give rise to inhalation exposure, but there is no indication of any adverse effects. ECETOC also noted PDMS is not a skin irritant or a skin sensitiser and it is only mildly to non-irritating to the eyes.
Thanks to extensive testing, the scientific body determined that there were no health risks due to use or exposure to PDMS through product use.
“Overall, PDMS does not present a risk to the environment or to human health,” said ECETOC.
The report was produced as part of the ECETOC Joint Assessment of Commodity Chemicals (JACC) programme and updates an earlier ECETOC review: JACC Report No. 26, from nearly 20 years ago.