Toothpaste (sodium lauryl sulfate) and cancer
Origin of the myth
Toothpaste, soap, shampoos, bath products and moisturisers often contain the chemicals sodium lauryl sulfate and sodium laureth sulfate. These two chemicals are very closely related.
The claim that sodium lauryl sulfate and sodium laureth sulfate cause cancer has been
propagated by emails and the internet. The suggestion is usually that they are harsh
chemicals used to clean garage floors, and are carcinogenic (cancer causing) when used
to clean skin. It is a myth highly exploited by 'natural products' businesses which use it
to convince consumers to buy their products.
Sodium Lauryl Sulfate
Sodium lauryl sulfate is used as a foaming agent and detergent in many skin care products.
The Cosmetic Ingredient Review (CIR) – an independent expert panel representing
consumers, industry and government in the US set up to assess the safety of ingredients
used in cosmetics – recently published an ingredient alert for the chemicals sodium
lauryl sulfate, sodium laureth sulfate (collectively, SLS) and ammonium lauryl sulfate.
This ingredient alert warned that SLS is an irritant, and the irritant property is higher at
greater concentrations. Additionally, the longer SLS is in contact with the skin, the
more likely it is to irritate. Hence, the alert warned that SLS is safe for brief use after
which it is rinsed away, as used in the shower or when brushing teeth. In products
which remain on the skin for prolonged periods of time, such as moisturiser and
cosmetics, SLS concentrations should not exceed 1%.
In Australia, the National Industrial Chemicals Notifications and Assessment Scheme
(NICNAS) reviewed studies conducted on the safety of sodium lauryl sulfate. It found
only one study conducted to examine the carcinogenic effects of sodium lauryl sulfate.
This study did not suggest that sodium lauryl sulfate caused cancer. NICNAS also found
no effect on fertility or development from use of sodium lauryl sulfate.
Sodium Laureth Sulphate
Sodium laureth sulfate has an emulsifying action (combining oil and water), which is
how it removes oil and soil.
Like sodium lauryl sulfate, it has been shown to irritate the eyes and skin in human and
animal studies. The severity of irritation increases with the concentration of sodium
laureth sulfate. Like sodium lauryl sulfate, there is no evidence that sodium laureth
sulfate is carcinogenic. The CIR has assessed the safety of sodium lauryl sulfate and
sodium laureth sulfate and concluded that they are safe.
The Report on Carcinogens is a list of known or reasonably anticipated human carcinogens
(cancer causing substances). Neither sodium lauryl sulfate nor sodium laureth sulfate are
included in this list.
There is no evidence for the carcinogenicity of either sodium lauryl sulfate or sodium laureth sulfate. NICNAS concludes that irritation is the only health hazard associated with the chemicals. This irritation only occurs at the high doses used in laboratory studies, and is unlikely to occur during normal household use.
- Cosmetic Ingredient Review (CIR). SLS (Sodium Lauryl Sulfate), Sodium Laureth
Sulfate, and Ammonium Laureth Sulfate Ingredient Alerts [cited 30/01/2008];
Available from: http://www.cir-safety.org/alerts.shtml.
- National Industrial Chemicals Notification and Assessment Scheme (NICNAS). Sodium Lauryl Sulfate. NICNAS Existing Chemicals Information Sheet 2007 [cited
30/01/2008]; Available from: http://www.nicnas.gov.au/Publications/Information_Sheets/Existing_Chemicals_Information_Sheets.asp
- U.S. Department of Health and Human Services, 11th Report on Carcinogens. 2005, Public Health Service - National Toxicology Program,.