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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 StrongConclusive
CarcinogenicityCarcinogenicity Tumor promoter

Documented links to breast cancer

Known human carcinogen

Carcinogenic in lab studies

Developmental & Reproductive ToxicityHormone Disruptor
Systemic Toxin
May cause blindness if used near the eyes

Hormone Disruptor

Systemic Toxin


May cause blindness if used

near the eyes

May interfere with male

reproductive health
67 - 8 9
Allergenicity & ImmunotoxicityAllergen

Asthma Trigger

45 - 67

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.

Product’s ingredients have potential serious negative long term health effects
Product’s ingredients have potential moderate negative long term health effects
Product does not contain any ingredients which have a documented potential negative health impact
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 OrganicECO 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.