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image source: PubChem
Health Concerns of the Ingredient:
Overall Hazard
Developmental &
reproductive toxicity
Other HIGH concerns: Irritation (skin, eyes, or lungs); Other LOW concerns: Data gaps, Ecotoxicology

About METHYLCHLOROISOTHIAZOLINONE: Methylchloroisothiazolinone is a widely-used preservative; has been associated with allergic reactions.

Function(s): Preservative



Concern Reference
Human skin toxicant or allergen - strong evidenceCosmetic Ingredient Review Assessments
Limited evidence of immune system toxicity or allergiesNordic Council of Ministers (Nordic Allergy Project)
Human skin toxicant or allergen - moderate evidenceLundov MD, T Krongaard, T L Menné & J D Johansen
Limited evidence of immune system toxicity or allergiesNational Library of Medicine HazMap

Use restrictions

Concern Reference
Restricted in cosmetics (recommendations or requirements) - use, concentration, or manufacturing restrictions - Use is restricted in Canadian cosmeticsCanada - Prohibited and Restricted Cosmetics Ingredients
Restricted in cosmetics (recommendations or requirements) - use, concentration, or manufacturing restrictions - Japan - concentration limit in some types of cosmetics when combined with certain other ingredient(s)Japan's Standards for Cosmetics
Restricted in cosmetics (recommendations or requirements) - use, concentration, or manufacturing restrictions - Japan - prohibited for use in some types of cosmetics when combined with certain other ingredientsJapan's Standards for Cosmetics
Determined safe for use in cosmetics, subject to concentration or use limitations - Safe for use in cosmetics with some qualificationsCosmetic Ingredient Review Assessments

Irritation (skin, eyes, or lungs)

Concern Reference
Possible human skin irritantNIOSH (Cook CK, Friedman D)


Concern Reference
Mutagen - limited evidenceConnor TH, Tee PG, Afshar M, Connor KM


Concern Reference
Wildlife and environmental toxicityU
Not suspected to be an environmental toxinEnvironment Canada Domestic Substance List

Data gaps

Concern Reference
Risk assessment method deficiencies and data gaps - Maximum reported "as used" concentration is basis of safety assessment by industry safety panel (Cosmetic Ingredient Review, CIR) - implicit safe concentration limit in productCosmetic Ingredient Review Assessments
178 studies in PubMed science library may include information on the toxicity of this chemical see search results ->NLM PubMed

Persistence and bioaccumulation

Concern Reference
Not suspected to be persistentEnvironment Canada Domestic Substance List
Not suspected to be bioaccumulativeEnvironment Canada Domestic Substance List

Organ system toxicity (non-reproductive)

Concern Reference
Classified as not expected to be potentially toxic or harmfulEnvironment Canada Domestic Substance List

Data Sources

CIR (Cosmetic Ingredient Review). 2006. CIR Compendium, containing abstracts, discussions, and conclusions of CIR cosmetic ingredient safety assessments. Washington DC.
Connor TH, Tee PG, Afshar M, Connor KM. 1996. Mutagenicity of cosmetic products containing Kathon. Environmental and molecular mutagenesis 28(2), 127-32.
EC (Environment Canada). 2008. Domestic Substances List Categorization. Canadian Environmental Protection Act (CEPA) Environmental Registry.
European Commission. 2013. Cosing, the European Commission database with information on cosmetic substances and ingredients. Accessed on March 1, 2013 at http://ec.europa.eu/consumers/cosmetics/cosing/ .
Health Canada. 2007. List of Prohibited and Restricted Cosmetic Ingredients. Canada's Cosmetic Ingredient Hotlist. March 2007.
IFRA (International Fragrance Assocication). 2010. IFRA Fragrance Ingredient List based on 2008 Use Survey. Accessed online 01/04/2010: http://www.ifraorg.org/Home/News/Latest-News/page.aspx/66?xf_itemId=43&xf_selectionDatapartId=25
Japan Ministry of Health, Labour and Welfare. 2006. Standards for Cosmetics. Evaluation and Licensing Division. Pharmaceutical and Food Safety Bureau.
Lundov MD, T Krongaard, T L Menné & J D Johansen. 2011. Methylisothiazolinone contact allergy: a review. The British journal of dermatology 165(6), 1178-82.
NIOSH (Cook CK, Friedman D). 1996. Health Hazard Evaluation Report, HEA 94–0402–2573. National Institute for Occupational Health and Safety.
NLM (National Library of Medicine). 2006. HazMap — Occupational Exposure to Hazardous Agents.
NLM (National Library of Medicine). 2012. PubMed online scientific bibliography data. http://www.pubmed.gov.
Nordic Council of Ministers (Nordic Allergy Project). Kriteriedokumenter fra nordisk allergiprojekt - vurdering af 50 kemiske stoffers evne til at forarsage allergi, en litteraturgennemgang. Nord 1991:51. Copenhagen, 1991.; Swedish National Chemicals Inspectorate. Labelling of chemical products, Swedish regulations and general advice with regard to the classification and labelling of chemical products hazardous to health, flammables and explosives. List of Allergenic Substances. National Chemicals Inspectorate, Solna, Sweden. 1987, 1990-1992.
U.S. Environmental Protection Agency (EPA). 1998. Reregistration Eligibility Decision (RED) Methylisothiazolinone. EPA738-R-98-012.

About the ratings

EWG provides information on personal care product ingredients from the published scientific literature, to supplement incomplete data available from companies and the government. The ratings below indicate the relative level of concern posed by exposure to the ingredients in this product - not the product itself - compared to other product formulations. The ratings reflect potential health hazards but do not account for the level of exposure or individual susceptibility, factors which determine actual health risks, if any. Learn more | Legal Disclaimer