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Purportedly in the interest of safeguarding commercially valuable intellectual property, personal care product manufacturers are permitted to conceal the composition of the fragrances they use in their products. An ingredient listed on a product label as “fragrance” may be composed of dozens of different synthetic chemical compounds, none of which are specifically identified on the label or the manufacturer’s website. Further, even products labeled ‘fragrance free’ have been shown to contain fragrance ingredients, typically due to the use of these compounds as preservatives or as agents to mask the odors of other chemicals in the product.1 Yet fragrance is the most common cause of contact dermatitis associated with personal care products.2 Even more alarmingly, chemical analyses of cosmetics and personal care products containing undisclosed “fragrance” ingredients have identified known allergens, asthma triggers, allergens, sensitizers, endocrine disruptors, carcinogens and neurotoxins.3,4,5

Due to the strong evidence of the potential negative health impacts of unspecified fragrance ingredients, Think Dirty® automatically assigns any product that lists “fragrance” on its label a rating of 7 or higher.

The assignment of numerical ratings based on the results of scientific studies is necessarily a subjective process. The information on our website and in our mobile applications is provided for informational purposes only and should not be construed as medical advice. If you have specific concerns about your exposure to certain chemicals or your health, please consult your physician.


  1. Heisterberg MV. et al. Deodorants are the leading cause of allergic contact dermatitis to fragrance
  2. Johansen JD. Fragrance contact allergy: a clinical review. Am J Clin Dermatol. 2003; 4(11):789-98.
  3. Llompart M. et al. Analysis of plasticizers and synthetic musks in cosmetic and personal care products by matrix solid-phase dispersion gas chromatography-mass spectrometry. J Chromatogr A. 2013 Jun 7; 1293:10-9.
  4. Koniecki et al. Phthalates in cosmetic and personal care products: concentrations and possible dermal exposure. Environ Res. 2011 Apr;111(3):329-36.
  5. EU CommissionsPublic consultation on fragrance allergens February 2014
  6. Not So Sexy: The health risks of secret chemicals in fragrance. Environmental Defence. May 2010.


CanadaHealth Canada Labelling of Cosmetics
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Toronto ChemTrac list of priority substances
Environment Canada Domestic Substance List
Environmental Defense Canada Toxic Ten
David Suzuki Foundation Dirty Dozen
EuropeEurope European Union Health Commission CosIng
(Cosmetics Ingredients & Substances)

Europe European Union Public Health
(Cosmetics Ingredients & Substances)

Danish Ministry of Environment Bans Database for Consumer Products, 2020
ChemSec SIN List
United StatesCHE Toxicant and Disease Database
National Library of Medicine: PubMed
California Safe Cosmetics Program Product Database
National Toxicology Program
Proposition 65: The Safe Drinking Water and Toxic Enforcement Act of 1986
Center for Disease Control Registry of Toxic Chemicals
US Food and Drug Administration – Cosmetics Products Ingredients
Cosmetic Ingredient Review Assessment
Campaign for Safe Cosmetics – Chemicals of Concerns
Cornell University: Breast Cancer and Environmental Risk Factors
Women’s Voice for the Earth
Breast Cancer Prevention Partner: Chemicals Linked to Breast Cancer
PETA Animal-Derived Ingredients:Beauty without Bunnies
INCI Dictionary
California Department of Toxic Substance Control
National Eczema Association
Safer Chemicals Healthy Families