5 star See our reviews

support our growth!

We are founded with a single-minded mission to give you access to ingredient-transparency. Contribute to fuels and lunches of our hard working interns / staff!

Think Dirty® Methodology

Think Dirty® is committed to helping consumers identify the potential risks associated with the personal care products they use every day. Unlike other ingredient databases, we focus exclusively on the chemical content of the products in question. We have consciously avoided the widely-used practice of “greenwashing”, whereby the environmental or social responsibility of a product’s manufacturer is factored into the assessment allowing a product to receive an artificially low toxicity rating. We remain an independent company with no affiliate to any other third parties. We are solely concerned about the possible impact of a given product on an individual’s health, and our ratings methodology reflects that singular commitment.

Our ratings are determined based on publicly available data released by non-profit and government agencies in North America regarding the health and safety of the individual components found in your personal care products. A list of our data sources can be found in Appendix A.

We assess the overall risk of a given product based on the potential health impacts of its published ingredients. Each ingredient listed on the product label or manufacturer’s website is evaluated for documented evidence of Carcinogenicity, Developmental & Reproductive Toxicity and/or Allergenicity & Immunotoxicity, as show in the table below.

Evaluations are performed by Chemistry Team and Advisory Board, all of whom have extensive experience in relevant fields such as Medicine, Biochemistry, Biology, Physiology, Environmental Toxicology, Environmental Health & Safety and Chemical Engineering, and a track record of working with Health Canada, the US Food & Drug Administration, the European Medicines Agency, Environment Canada, the US Environmental Protection Agency and other related government and not-for-profit agencies.

Potential Health Potential Action of Ingredients Rating Based on Strength of Evidence
Impact of Ingredient According to Published Evidence Moderate Strong Conclusive

Carcinogenicity Tumor promoter

Documented links to breast cancer

Known human carcinogen

Carcinogenic in lab studies


9 10 10
Developmental & Reproductive Toxicity

Hormone Disruptor

Systemic Toxin


May cause blindness if used

near the eyes

May interfere with male

reproductive health

6 7 - 8 9
Allergenicity & Immunotoxicity


Asthma Trigger


4 5 - 6 7

By default, products receive an overall Think Dirty® rating no lower than the highest rating of any individual ingredient.

If several ingredients in a given product receive high ratings, the product itself is automatically assigned a Think Dirty® rating of 10. It is important to note that even though some of the ingredients in personal care products may be present in very small quantities, the likelihood of significant repeated exposure is high due to the frequency with which personal care products are typically used. It is widely acknowledged that even low-level exposure to known toxins can have deleterious effects on human health if the exposure is repeated and long-term.

On a case by case basis, some products’ overall ratings might not be defaulted to the highest rating of any given ingredients. For example, if the total percentage of 4-7 rated ingredients is less than 5%, the outcome of the overall ratings might not be defaulted to the highest rating of the any individual ingredient.

Another example is that if a product has been certified by credible certifiers, the overall product ratings will be reviewed and evaluated on a case by case basis. Again, the outcome of the overall ratings might not be default to the highest rating of the any individual ingredient. If an overall product rating is adjusted because of credible certifiers, users can view certifiers types earned under in-app Certifiers tab in each product listing.

For more details on policy on organic certifiers, please refer “The Certifiers” section of this page.

The Think Dirty® Product Rating Scale, Dirty Meter® is defined in the table below.

Dirty Meter® definition
8 - 10 Product’s ingredients have potential serious negative long term health effects
4 - 7 Product’s ingredients have potential moderate negative long term health effects
0 - 3 Product does not contain any ingredients which have a documented potential negative health impact
N/R Ingredients not yet rated

In some cases manufacturers choose to define a component or group of components as proprietary and therefore confidential, in which case the specific ingredients in that component are not publicly disclosed and cannot be evaluated using existing health and safety data. This is a particular issue with an ingredient found on many personal care products, which is simply listed as “fragrance”. The sidebar below describes the significant potential health risks associated with “fragrance”, and our approach to rating products that contain this inscrutable ingredient.


In recognition of some manufacturers who chose to voluntarily submit their products for rigorous third parties certifiers such as USDA Organic, ECO Cert and NSF. We are in the process of rating these certified products with more positive rating than the products with same ingredients but not certified.

the fragrance loophole

  • 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 ingredients. Contact Dermatitis: 64(5):258-64, May 2011.
  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.

appendix a

  • 4.5KBrands
  • 1.4MProducts
  • 26.2MUnique Scans

stay in touch and sign up to get updates

What the others are saying

Think Dirty tweets

We spot dirty and clean on instagram


Recognized By


Featured by

As seen on