About Environmental Working Group's Skin Deep

It's our mission at the Environmental Working Group to use the power of information to protect human health and the environment.

Often, that means building databases. EWG's data gives you practical solutions to protect yourself and your family from the health risks we all face from everyday exposures to myriad industrial chemicals.

In 2004 we launched Skin Deep, an online safety guide for cosmetics and personal care products. Our aim was to fill in where companies and the government leave off: companies are allowed to use almost any ingredient they wish, and our government doesn't require companies to test products for safety before they're sold. EWG's scientists built Skin Deep to be a one-of-a-kind resource, integrating our in-house collection of personal care product ingredient listings with more than 50 toxicity and regulatory databases.

Now in its fourth year and third major update, our Skin Deep database provides you with easy-to-navigate safety ratings for nearly a quarter of all products on the market — 52,673 products with 8,844 ingredients. At about one million page views per month, Skin Deep is the world's largest and most popular product safety guide.

And we don't stop with shopping tips. EWG is also working to fix the policies that allow our over-exposure to toxic chemicals. Sign our petition to Congress demanding product safety testing.

Read more:
• About the Campaign for Safe Cosmetics
• Quick facts on Skin Deep
• Skin Deep Product and Ingredient Databases
• Data sources - toxicity, regulatory, and study availability databases
• Skin Deep's Dual Rating Factors

About the Campaign for Safe Cosmetics

Skin Deep helps fuel the nationwide Campaign for Safe Cosmetics, a coalition of public health, educational, religious, labor, womens, environmental and consumer groups working to protect the health of consumers and workers by requiring the health and beauty industry to phase out the use of dangerous chemicals and replace them with safer alternatives. Through the Campaign, as of May 2007 over 500 companies have joined the effort by signing the Compact for Safe Cosmetics. Environmental Working Group is a founding partner of the Campaign.

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Quick facts on Skin Deep

Skin Deep contains information and online safety assessments for:

• 52,673 products
• 8,844 ingredients
• 2,445 brands
• 1,621 companies

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Skin Deep Product and Ingredient Databases

Below we describe the data sources and the methodology we use to construct Skin Deep's linked databases of ingredients, products, brands, companies, hazards, testing availability, and regulatory status.

Obtain and Process Products in Skin Deep's database

Product and ingredient data collection. One of the core components of Skin Deep is an electronic product database that details ingredients in 52,673 products as of Feb 09, 2007. We obtained data for products from online retailers,from manufacturers who entered product information directly to the site (a tool we provide to companies who have signed the Compact for Safe Cosmetics), and, to a lesser extent, through other methods described below. In most cases label information includes company, brand, product name, ingredients, warnings, and directions for use.

1. 38,592 products: EWG gathered product label information in electronic format from a variety of online retailers of personal care products since April 2006.
2. 3,702 products: EWG's partner organizations in the Campaign for Safe Cosmetics collected product label information in 2005 through three routes: via a series of email requests to Estee Lauder (which in early 2005 followed a policy allowing 10 product label requests per email, although they later refused to send additional label information); through manual data entry while reading the data on a product container; and by culling electronic ingredient label information from various online sources.
3. 10,257 products: Since January 2006, through the partnership with the Campaign for Safe Cosmetics, the Environmental Working Group has regularly updated Skin Deep with products available from companies who have signed the Campaign's Compact for Safe Cosmetics. EWG provides companies with access to a "Manufacturer's Page" within Skin Deep that allows them to enter into the database information on all of the products they manufacture, including product names, ingredients, and information on how the product is used and to whom it is marketed. The Compact requires that companies enter all products into Skin Deep by July 1, 2007, or within six months of signing the Compact for companies who signed after January 1, 2007. As of May 2007, 629 of 1,453 total Compact-signing companies have entered products into Skin Deep via the tools on the Manufacturer's Page.
4. 122 products: In October 2005 we released a new tool within Skin Deep that allowed site users to enter products into our online database that their own search revealed were not already in the site Immediately after entering product label and product use information, the site user received a preliminary safety assessment report on the product, built on Skin Deep's product and ingredient rating system. The information entered by the user was stored in a "queue" database that EWG reviewed periodically. After EWG scientists made any necessary corrections, they ported products into our live, online database to become an integral part of the Skin Deep website. Ensuring the accuracy of user-entered information proved a time-intensive job, beyond our resources. We have temporarily suspended this feature in Skin Deep as we explore alternate possibilities for assessing the quality of data entered by site users.
   
   Between October and December 2005 when this product entry feature was suspended, Skin Deep users entered 9,367 products into the site altogether, 122 of which EWG researchers thoroughly reviewed and ported in Skin Deep's publicly accessible database, and the remaining 9,245 of which had been available for viewing in their draft, unreviewed form by Skin Deep users who searched for a product with a name identical to one already entered by another site user. We expect to relaunch this popular product entry tool for Skin Deep users shortly after the site's May 2007 upgrade.

Product type information. EWG's product database structure within Skin Deep comprises eight major product categories — skin care, makeup, hair care, nails, eye care, feminine hygiene, dental and oral hygiene, and fragrances. Within these eight major categories are more than 90 product sub-type categories (e.g., shampoo, toothpaste, deodorant). EWG assigns appropriate categories and sub-categories to each product entered into Skin Deep's database, or reviews the categories assigned by product manufacturers who enter their products through the Manufacturer's Page accessible by companies who sign the Compact for Safe Cosmetics.

Product use information. We also record information on how the product is typically used. This information is an integral component of product safety assessment ratings — many hazards or safety recommendations associated with particular chemicals are a function of use, applying, for instance, only for inhalation exposures or for products that are not rinsed off the skin after they are applied. We compile the following data for each product entered into the database, or review these data for products added by site users:

• Body areas exposed: skin, face, lips, around the eyes, hair or scalp, in the mouth, on damaged or cracked skin, on nails or cuticles, or on areas for feminine hygiene.
• Type of exposure: product left on after application, rinsed off, or wiped off.
• Form of the product: solid, cream, liquid, gel, mousse, packed powder, loose powder, spray, aerosol.

Product demographic information. For use in specialized displays of product information, we compile demographic information on the product's intended users, recording if the product is intended primarily for women or men, or if the product is marketed for use by people of color, teenagers, children (2 to 10), or infants (0 to 2).

Ingredients in Skin Deep's database

Skin Deep currently contains information on nearly 151,843 unique personal care product ingredients, as culled from ingredient labels on 52,673 products and from the scientific and industry literature on personal care products. We assign a standardized name to each ingredient that we enter into the Skin Deep database, generally taken as the International Nomenclature for Cosmetic Ingredients (INCI) standard, with some exceptions where alternate names are more easily recognized by consumers. Each of these ingredient names is associated with a unique ingredient identification number in our database. The processing steps for ingredients are described below.

Obtaining product ingredient listings. EWG researchers built Skin Deep's ingredient database from the sources listed below; some ingredients are found in more than one of these sources. Each of these ingredients is contained in Skin Deep's ingredient database. Skin Deep users can navigate to a unique safety report for each of these ingredients via the site's search function or through site pages that provide data on companies, brands, and products.

EWG researchers constructed Skin Deep's ingredient database from the raw product data described above. First we parsed all the ingredient label data into the 151,755 unique ingredients and spellings that were listed on products labels. Then we correct misspellings in ingredient names, and combined ingredients that are synonyms of the same chemical into a single unique chemical assigned a unique chemical identifier in Skin Deep. The final ingredient database composites the 151,755 original chemical names into 8,844 unique chemical ingredients. (Through this work we see that companies routinely ignore FDA requirements for standard ingredient nomenclature, with each ingredient being shown an average of 17 different ways on the labels of the various products containing it.) Ingredients in Skin Deep come from the following sources:

• Product ingredient listings. The 52,673 products contained in the Skin Deep product database list 151,755 uniquely spelled ingredients on their labels, which we condensed to 8,844 unique chemicals after extensive synonym matching.
• Industry ingredient listings. The International Cosmetics Ingredient Dictionary and Handbook (Tenth Edition, 2004, published by the Cosmetic, Toiletry, and Fragrance Association, Inc.) contains "name monographs" for 491 ingredients listed under their International Nomenclature for Cosmetic Ingredients (INCI) designations. EWG researchers entered these ingredients into the Skin Deep ingredient database.
• Industry-reviewed ingredients. The personal care product industry's internal safety panel, the Cosmetic Ingredient Review, had assessed the safety of 1,420 ingredients as of their latest compendium publication (Cosmetic Ingredient Review (CIR), 2006 CIR Compendium, Washington, DC). EWG researchers entered each of these ingredients (and accompanying safety findings made by the panel) into Skin Deeps' ingredient database.
• Ingredients from toxicity, regulatory, and study availability databases. We imported these additional ingredients into the database from the more than 50 data sources we have compiled on the toxicity, regulatory status and study availability of chemicals in personal care products. These sources are listed below under a section titled "Data Sources."
• Manufacturer-entered ingredients ingredients. Skin Deep contains information on ingredients in products entered into the site by manufacturers via the product entry tools we make available to companies who have signed the Compact for Safe Cosmetics via the Campaign for Safe Cosmetics. Most of these ingredients are also found in other ingredient sources listed above; some are unique, found in none of our other data sources.
• Ingredients entered by site users. Skin Deep also contains information on ingredients entered into the site by Skin Deep users via the product entry tools that were live on the site from October 2005 to May 2007. As with the ingredients entered by manufacturers, many of these ingredients are also found in other sources listed above; some are unique, found in none of our other data sources. We have not reviewed the validity of these unique ingredients or assessed whether site users entered the ingredients in error.

Creating electronic ingredient lists from product labels. For product labels obtained from online retailers, we first process the ingredients with a parsing program that separates individual chemicals listed on the label. The automated parsing tools we have designed do not yet take into account every variance in labeling and will likely never be able to account for the wide range of errors in spacing and chemical delimiting we find on the ingredient labels we import into Skin Deep. Because of these factors, our programs do not perfect parse every ingredient, so we carefully review the result and manually correct ingredients that are not accurately parsed. These parsing steps are not necessary for new products the manufacturers enter via the product entry tool in the Skin Deep website, which requires ingredients to be entered one at a time.

Assigning unique chemical name and identification number to ingredients. We assign each ingredient a unique name and identification number within Skin Deep's ingredient database, in a multi-step process that often involves resolving chemical synonyms and names that are misspelled or that do not follow standard industry naming conventions:

• For ingredients on product labels or company entries that exactly match the spelling of one of our core database ingredients or its synonyms, we assign that ingredient the existing chemical name and identification number from our ingredient database.
• For ingredients that do not exactly match an existing ingredient name, we identify if the new ingredient is a misspelling of an ingredient in our core database. We process the new ingredient with a program that identifies possible name matches, first through a match of Chemical Abstract Service (CAS) identification numbers when they are available, and secondly, through a custom, chemical-name spell checker. Then through a manual review of these tentative matches, we either match the new ingredient with one already existing in our database, or we determine that it is a new, unique ingredient, and assign it a new ingredient identification number. This manual review draws from a variety of sources, including our reviews of cosmetic industry literature (such as the Cosmetic Ingredient Review articles (CIR 2006), the International Cosmetic Ingredient Dictionary and Handbook (CTFA 2004), or one of several other chemical databases. We also contact companies directly with questions about their ingredients. EWG's own chemical databases contain over 250,000 structures with more than 1,000,000 unique synonyms when combined with other available sources such as the National Library of Medicine's Chem ID Plus (NLM 1994) or the Environmental Protection Agency's Substance Registration System (EPA 2006), the US Department of Agriculture Plant Database (USDA-NRCS 2007).

Additional data stored with ingredient names. We also store in our ingredient database additional listed information about the ingredient — for instance, its status as an "active ingredient" in the product; its listing under "may contain," or "organic" under USDA standards; or its association with modifiers that indicate manufacturing methods, like USP for United States Pharmacopeia standards or NF for National Formulary standards.

Brand and company information in Skin Deep's database

Skin Deep currently holds products sold under 2,445 brand names and manufactured by 1,621 companies. To build this core brand and company database, we first estimated brand names as an extraction of the first words in product names, or relied on a listed brand name from product information originally extracted electronically, if available. We then manually corrected each estimated brand name, as needed, and associated each brand with a manufacturer. We did this primarily through online research of manufacturer websites and to a lesser extent through direct contact with manufacturers. We also linked manufacturers with parent companies, as appropriate, again primarily through online research. This brand and company database forms an integral part of the Skin Deep data structure.

Because animal testing is an issue of concern for many consumers, we also incorporate into Skin Deep information on company and brand stances on animal testing. Information on company positions on animal testing is obtained from People for the Ethical Treatment of Animals' (PETA) index. Brands are noted for their stance on animal testing based on a review of official statements provided by their parent companies to PETA. We will periodically update our Skin Deep database according to changes in PETA's roster.

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Data sources - toxicity, regulatory, and study availability databases

EWG created a core database of chemical hazards, regulatory status, and study availability by pooling the data of more than 50 databases and sources from government agencies, industry panels, academic institutions, or other credible bodies. Collectively, these data sources detail more than 1,535 unique chemical classifications. These data comprise the keystone of the hazard and data gap assessments that are integral to Skin Deep, which build on a pairing of this toxicity, regulatory, and study availability database with EWG's ingredient database. Individual toxicity, regulatory, and study availability data sources we compiled are listed below.

Primary references - Known and probable carcinogens, reproductive and developmental toxicants

• ACGIH (American Conference of Governmental Industrial Hygienists) 2004. ACGIH cancer classification system. www.acgih.org. [1]
• California EPA (California Environmental Protection Agency). 2006. Office of Environmental Health Hazard Assessment. Safe Drinking Water and Toxic Enforcement Act of 1986. Chemicals known to the State to cause cancer or reproductive toxicity. [2]
• ECB (European Chemicals Bureau). 2006. Classification and Labelling: Chemicals: Annex I of Directive 67/548/EEC. [3]
• EPA (U.S. Environmental Protection Agency). 2006. Integrated Risk Information System (IRIS). Evidence for human carcinogenicity based on 2005 guidelines. [4]
• IARC (International Agency for Research on Cancer). 2006. Overall Evaluations of Carcinogenicity to Humans, as evaluated in IARC Monographs Volumes 1-88 (a total of 900 agents, mixtures and exposures). [5]
• NTP (National Toxicology Program). 2005. Eleventh Report on Carcinogens, Eleventh Edition; U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program. [6]

Secondary references - Known and probable carcinogens, reproductive and developmental toxicants

• CHE (The Collaborative on Health and the Environment). 2006. Toxicant and Disease Database. [7]
• ED (Environmental Defense). 2006. Scorecard _ The Pollution Information Site. http://www.scorecard.org. [8]
• EPA (U.S. Environmental Protection Agency). 2006. EPA Water Disinfection By-Products with Carcinogenicity Estimates. Last updated: 10 April 2006. [9]
• Grandjean P and PJ Landrigan. 2006. Known human neurotoxins from: Developmental neurotoxicity of industrial chemicals. Lancet. 2006 Dec 16;368(9553):2167-78. [10]
• NIOSH (National Institute for Occupational Safety and Health). 2006. NIOSH Carcinogens List (Potential occupational carcinogens). http://www.cdc.gov/niosh/npotocca.html. [11]
• NTP (National Toxicology Program) 2006. Chemicals Associated with Site-Specific Tumor Induction in Mammary Gland. [12]

Other health endpoints (neurotoxicity, immunotoxicity, etc.)

• AOEC (Association of Occupational and Environmental Clinics). 2006. Asthmagen compilation - AEOC exposures codes.[13]
• CIR (Cosmetics Ingredient Review). 2005. CIR Compendium, containing abstracts, discussions, and conclusions of CIR cosmetic ingredient safety assessments. Washington DC. [14]
• ECB (European Chemicals Bureau). 2006. Classification and Labelling: Chemicals: Annex I of Directive 67/548/EEC. [3]
• ED (Environmental Defense). 2006. Scorecard _ The Pollution Information Site. http://www.scorecard.org. [8]
• EPA (U.S. Environmental Protection Agency). 1987 & 2005. Office of Pesticide Programs. Inert (other) Pesticide Ingredients in Pesticide Products - Categorized List of Inert (other) Pesticide Ingredients. [15]
• FDA (U.S. Food and Drug Administration). 1993. Center for Food Safety and Applied Nutrition. Unsubstantiated Claims and Documented Health Hazards in the Dietary Supplement Marketplace. Illnesses and Injuries Associated With the Use of Selected Dietary Supplements. [16]
• FDA (U.S. Food and Drug Administration). 2000. FDA Center for Food Safety and Applied Nutrition. Cosmetics Compliance Program. Domestic Cosmetics Program. Coverage of Bovine-Derived Ingredients for Bovine Spongiform Encephalopathy (BSE). Issued July 31, 2000. [17]
• Illinois EPA (Illinois Environmental Protection Agency), 2000. Preliminary list of chemicals associated with endocrine system effects in animals and humans or in vitro. In EPA (U.S. Environmental Protection Agency), 2000. Handbook for Non-Cancer Health Effects Valuation, Appendix C. [18]
• NLM (National Library of Medicine). 2006. HazMap — Occupational Exposure to Hazardous Agents. [19]
• NTP (National Toxicology Program). 2006. NTP Center for the Evaluation fo Risks to Human Reproduction (CERHR). NTP-CERHR Reports and Monographs. [20]
• RTECS (Registry of Toxic Effects of Chemical Substances). 2007. Developed by National Institute for Occupational Safety and Health (NIOSH), currently maintained by Elsevier/MDL. [21]
• Colborn T, D Dumanoski, JP Myers. 2006. Widespread Pollutants with Endocrine-disrupting Effects. Updated from original listing in "Our Stolen Future" (1996).[22]

Restrictions and warnings on safe use of ingredients in cosmetics

• CIR (Cosmetic Ingredient Review). 2005. CIR Compendium, containing abstracts, discussions, and conclusions of CIR cosmetic ingredient safety assessments. Washington DC. [14]
• CTFA (Cosmetic, Toiletry and Fragrance Association). 2006. International Cosmetic Ingredient Dictionary and Handbook, 11th Edition. Color Additive Information. Washington, DC. [23]
• EC (European Commission of the European Union). 1999-2006. Enterprise Directorate-General Pharmaceuticals and Cosmetics. The rules governing cosmetic products in the European Union, Volume 1, "Cosmetics legislation." [24]
• FDA (U.S. Food and Drug Administration), 2006. Ingredients Prohibited and Restricted [in Cosmetics] by FDA Regulations. FDA Center for Food Safety and Applied Nutrition, Office of Cosmetics and Colors. Downloaded from http://www.cfsan.fda.gov/~dms/cos-210.html. [25]
• FDA (U.S. Food and Drug Administration) 2006. Center for Food Safety and Applied Nutrition. Color Additive Status List. September 2006. [26]
• Health Canada. 2007. List of Prohibited and Restricted Cosmetic Ingredients. Canada's Cosmetic Ingredient Hotlist. March 2007. [27]
• IFRA (International Fragrance Association). 2006. Codes and Standards. [28]
• Japan Ministry of Health, Labour and Welfare. 2006. Standards for Cosmetics. Evaluation and Licensing Division. Pharmaceutical and Food Safety Bureau. [29]
• SCCPNFP (Scientific Committee On Cosmetic Products And Non-Food Products). 1999. Opinion Concerning Fragrance Allergy In Consumers. . SCCNFP/0017/98 Final, December 1999; and SCCPNFP (Scientific Committee On Cosmetic Products And Non-Food Products). 2000. An Initial List Of Perfumery Materials Which Must Not Form Part Of Fragrances Compounds Used In Cosmetic Products. SCCNFP/0320/00, final May 2000. [30]

Persistent Bioaccumulative Toxics

• Aarhus LRTAP. 1998. Aarhus Protocol on Persistent Organic Pollutants (POPs). Geneva Convention on Long-range Transboundary Air Pollution, United Nations Environment Program. [31]
• EC (Environment Canada). 1994. Persistent Bioaccumulative and Toxic (PBT) Chemical Program. [32]
• EC (Environment Canada). 1994. Accelerated Reduction/Elimination of Toxics (ARET). ARET substance list of persistent, bioaccumulative and toxic chemicals. [33]
• EPA (U.S. Environmental Protection Agency). 1998. Resource Conservatin and Recovery Act (RCRA) Waste Minimization Program - priority chemicals for elimination or reduction. [34]
• EPA (U.S. Environmental Protection Agency). 1999. Toxics Release Inventory Program. PBT Chemical Rule. [35]
• EU (European Union). 2006. Persistent, bioaccumulative chemicals identified in PRIO database - a tool for risk reduction of chemicals. Secondary PRIO database - a tool for risk reduction of chemicals. Secondary Kemi. Place Published, Kemi-Swedish Chemicals Inspectorate. [36]
• Great Lakes BTS (Binational Toxics Strategy). 1997. Canada-United States Strategy for the Virtual Elimination of Persistent Toxic Substances in the Great Lakes. Appendix I - Level 1 and Level 2 substances. [37]
• OSPAR (Oslo-Paris). 2002. OSPAR List of Substances of Possible Concern. Secondary OSPAR List of Substances of Possible Concern. Secondary OSPAR. Place Published, OSPAR Convention for the Protection of the Marine Environement of North-East Atlantic. [38]
• UNEP (United Nations Environment Programme). 2001. Stockholm Convention on Persistent Organic Pollutants (POPs) — POPs Treaty. [39]

Other resources relevant to consideration of human health risks

• EPA (U.S. Environmental Protection Agency). 2005. Office of Air. The 112(b)1 Hazardous Air Pollutants List (as modified). Last modified: 12 Dec 2005. [40]
• EPA (U.S. Environmental Protection Agency). 2005. Office of Water. National Water Quality Standards Database. Clean Water Action priority pollutants. Eighth release. September 2005. [41]
• EPA (U.S. Environmental Protection Agency). 2005b. Priority PBT (Persistent, Bioaccumulative, Toxic) Chemicals. EPA Office of Prevention, Pesticides and Toxic Substances. [42]
• EPA (U.S. Environmental Protection Agency). 1998. Waste Minimization Program (RCRA) - persistent, bioaccumulative, and toxic chemicals. [43]
• EPA (U.S. Environmental Protection Agency). 1999. Toxic Release Inventory - persistent, bioaccumulative, and toxic chemicals. [44]
• EU (European Union). 2000. Water Framework Directive (Directive 2000/60/EC) - integrated river basin management for Europe. List of priority substances. [45]
• FDA (U.S. Food and Drug Administration) 2006. Food Additive Status List. Downloaded from http://www.cfsan.fda.gov/%7Edms/opa-appa.html, Oct 16, 2006. [46]
• FDA (U.S. Food and Drug Administration) 2006. Center for Food Safety and Applied Nutrition. Color Additive Status List. September 2006. [47]
• FDA (U.S. Food and Drug Administration). 2006. EAFUS [Everything Added to Food]: A Food Additive Database. FDA Office of Food Safety and Applied Nutrition. [48]

Availability of safety data

• CIR (Cosmetic Ingredient Review). 2005. CIR Compendium, containing abstracts, discussions, and conclusions of CIR cosmetic ingredient safety assessments. Washington DC. [14]
• EPA (U.S. Environmental Protection Agency). 1998. Chemical Hazard Data Availability Study. High Production Volume (HPV) Chemicals and SIDS Testing. Master Summary for the Chemical Hazard Data Availability Table. [50]
• FDA (U.S. Food and Drug Administration). 2005. EAFUS [Everything Added to Food]: A Food Additive Database. FDA Office of Food Safety and Applied Nutrition. [51]

Human exposure factors

• EWG (Environmental Working Group). 2007. National Tap Water Quality Database. EWG compilation of tap water testing data from 42 states and more than 40,000 communities nationwide, 1998-2003. Available online at http://www.ewg.org/sites/tapwater/. [52]
• EWG (Environmental Working Group). 2007. Biomonitoing findings from studies across the U.S. Human Toxome Project: Monitoring the Pollution in People. Available online at http://www.ewg.org/sites/humantoxome/. [53]
• CDC (Centers for Disease Control and Prevention. 2005. National Exposure Report. Biomonitoring data collected under the National Health and Nutrition Examination Program. [54]
• NanoWerk. 2007. Nanomaterial Database. Available online: http://www.nanowerk.com/phpscripts/n_dbsearch.php. [55]

Study/assessment availability sources

• CIR (Cosmetic Ingredient Review). 2005. CIR Compendium, containing abstracts, discussions, and conclusions of CIR cosmetic ingredient safety assessments. Washington DC. [14]
NLM (National Library of Medicine). 2007. PubMed online scientific bibliography data. http://www.pubmed.gov. [56]

Chemical nomenclature databases

• CIR (Cosmetic Ingredient Review). 2005. CIR Compendium, containing abstracts, discussions, and conclusions of CIR cosmetic ingredient safety assessments. Washington DC. [14]
• CTFA (Cosmetic, Toiletry and Fragrance Association). 2006. International Cosmetic Ingredient Dictionary and Handbook, 11th Edition. Color Additive Information. Washington, DC. [23]
• NLM (National Library of Medicine). 1994. ChemID Plus. [57]
• EPA (U.S. Environmental Protection Agency). 2006. Substance Registry System. [58]
• USDA-NRCS (U.S. Department of Agriculture, National Resource Conservation Service). 2007. The PLANTS Database, National Plant Data Center, Baton Rouge, LA 70874-4490 USA. [59]

Linking ingredients to chemicals in toxicity and regulatory databases

We cross-linked the chemical names in our ingredient database with the names contained within our toxicity, regulatory, and study availability databases. These pairs form the basis for the hazard assessment ratings and data gap ratings that are an integral part of Skin Deep.

For an initial estimate of the chemical pairings between these two databases, we linked together chemicals when names matched perfectly between data sources; when Chemical Abstract Service (CAS) numbers matched, when they were available from our in-house CAS database; or when strings of letters matched between ingredients.

This initial process created over 195,524 initial name pairings, which we reviewed manually. We "unlinked" pairs when we found that the corresponding ingredient names were not, in fact, the same chemical. For many pairings we conducted a detailed review of the validity of the match between an ingredient and a hazard category, storing data on hazards that apply only to a particular route of exposure, for instance, for use in the hazard scores we developed for ingredients.

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Skin Deep's Dual Rating Factors

Introduction. Skin Deep relies on a dual rating system to inform consumers about product safety:

• Hazard (concern) rating. We developed a hazard rating that represents a synthesis of known and suspected hazards associated with ingredients and products. Hazard ratings within Skin Deep are shown as low, moderate, or higher concern categories, with numeric rankings spanning those categories that range from 0 (low concern) to 10 (higher concern).
• Data gap rating. We developed a data gap rating within Skin Deep, primarily to describe the extent to which low hazard scores associated with some ingredients or products are based on definitive data demonstrating safety or, at the other extreme, on a near absence of data either demonstrating or disproving hazard. Data gap ratings are represented within Skin Deep by a numeric percentage ranging from 100% (complete absence of safety data) to 0% (comprehensive safety data).

Database processing for dual rating system. Both of Skin Deep's rating factors (hazards and data gaps) are calculated from information drawn from the more than 50 integrated toxicity, regulatory, and study availability databases. To construct Skin Deep's rating factors, we divided the toxicity and regulatory databases in Skin Deep into their component pieces, each of which has a specific relevance to one of the two major rating factors. We divided the databases into 260 individual categories ranging from "known human carcinogen according to EPA" to "skin irritant identified by the Cosmetic Ingredient Review panel." We then mapped each of these categories into one of 205 "score categories" that are detailed in the table below. We ranked each score category according to a subjective assessment of its relative importance to public health or regulatory compliance, and then assigned a weight to each score category, also described in tables below.

Calculating the hazard (concern) rating

The hazard score on Skin Deep is calculated in pieces.

Ingredients

1. We categorize the studies and data into 17 general hazard categories: cancer, reproductive/developmental toxicity, neurotoxicity, endocrine disruption potential, allergies/immunotoxicity, violations/restrictions/warnings, organ system toxicity, persistence/bioaccumulation, multiple/additive exposure, mutations, cellular/biochemical changes, ecotoxicity, occupational hazards, irritation, absorption, impurities, and miscellaneous.
2. Each study/data source is then assigned a score between 0 and 100 based on the weight of evidence. For example, a "known human carcinogen" is assigned a 100 for the cancer category while a "probable human carcinogen" is given a much lower score (55). The breakdown for each category may be found in tables below.
3. Next, we calculate overall ingredient scores in each of the 17 categories:
   • For violations/restrictions/warnings, multiple/additive exposure, impurities, and miscellaneous, we simply add up all the scores assigned in step 2. This means that the "violations/restrictions/warnings" score for a chemical banned in Europe & Japan will be higher than a chemical only banned in Europe.
   • For the remaining categories, we apply the highest score found to that category for that ingredient. This means that if a chemical was determined to be a "known human carcinogen" by EPA and a "probable human carcinogen by the EU, it will only receive the score for being a "known human carcinogen".
4. These category scores (except absorption) are weighted and then summed to produce a raw score. (The weighting factors are listed in a table below.)
5. We then weight the raw ingredient score by the absorption category score. The absorption category scores take into account the particle size and it's penetration enhancing ability.
   
   

   Products

6. We return to the 17 categories to calculate a product score. For each category (except absorption), we add the highest scoring ingredient to the average score for the rest of the ingredients. Let's use an example product made of water, coal tar, and sodium chlorite. For this strange combination, the cancer score would be 100 (from the known carcinogen score for coal tar) + 15 (from the average of water [0] and sodium chorite [30 - limited evidence]). The resulting raw cancer score would be 115.
7. Just as with an ingredient, these category scores (except absorption) are weighted and then summed to produce a raw score. (The weighting factors are listed in a table below.)
8. We then weight the raw product score by the absorption category score. For products, the absorption weighting factor includes an assessment of penetration enhancers, nano-scale ingredients, and blocking ingredients.
   
   

   Final scaling of hazard scores

9. In the final step for deriving product and ingredient hazard scores, all scores are scaled from 0 to 10, with 10 being ingredients and products with the greatest concern, 0 being ingredients and products with the least concern. We assign a score of 10 to the top 5% most hazardous products and ingredients, and then scale down uniformly to 0 for scores lower than this.

Major categories of concern and their weighting factors. We categorized every piece of toxicity and hazard information in our integrated database into one of 19 different major categories. We developed these categories based on our review of available data, and modeled them after a variety of toxicity classification systems developed by government, industry, and academic organizations. We assigned to each of these categories a weighting factor representing a judgment on their relative importance to and impact on human health. We assigned higher weighting factors to categories of health concern for which studies provide evidence for effects at low doses, for permanent effects stemming from exposures during development, for toxicity endpoints that tend to impact multiple biological systems in the body or to impair reproduction. These endpoints include cancer, reproductive and development effects, immunotoxicity, neurotoxicity, and effects stemming from exposures to endocrine (hormone) disruptors. Organ systems that are more localized, such as gastrointestinal, kidney, respiratory, etc. are weighted in the mid-range. Toxic endpoints that measure adverse effects at the cellular level, which may or may not have implications for human health (such as mutations or biochemical changes) are weighted the least. This scoring system does not account for individual sensitivities or differences between the severities of different health endpoints within a particular category.

Table 1
Hazard categories and weighting factors

Category	Weighting factor	Description
Cancer	1.0	linked to cancer in government, industry, or academic studies or assessments.
Developmental/reproductive toxicity	1.0	linked to developmental and reproductive toxicity, a broad class of health effects that can range from infertility and reproductive organ cancers to birth defects and developmental delays for children.
Neurotoxicity	1.0	linked to neurotoxicity, or harm to the brain and nervous system, a class of health problems that can range from subtle developmental delays to chronic nerve degeneration diseases.
Endocrine disruption	1.0	the body's natural hormones, the chemicals that carry messages across the body to manage growth, tissue repair, and reproduction.
Allergies/immunotoxicity	1.0	linked to immunotoxicity, or harm to the immune system, a class of health problems that manifest as allergic reactions or an impaired capacity to fight disease and repair damaged tissues in the body.
Miscellaneous	1.0	Includes toxicity endpoints that didn't fit in another category, efficacy scores (scores that might counteract toxicity scores), and scores for unidentified ingredients.
Violations, restrictions & warnings	0.9	prohibited for use in cosmetics, or subject to concentration, use, or manufacturing method restrictions, according to industry safety guidelines and government requirements and guidance from the U.S., E.U., Japan, and Canada.
Organ system toxicity (non-reproductive)	0.5	linked to toxicity of one or more biological systems in the body (cardiovascular, stomach and digestive trace, respiratory system, etc.) through laboratory studies or studies of people.
Persistence and bioaccumulation	0.3	persistent and/or bioaccumulative, resisting normal chemical breakdown in the environment; building up in wildlife, the food chain, and people; and lingering in body tissues for years or even decades after exposure.
Multiple, additive exposure sources	0.3	also found as contaminants in tap water and food, as ingredients in other kinds of consumer products, or in people in biomonitoring studies that measure chemicals in blood, urine, and other fluids and tissues.
Mutations	0.3	linked to both cancer and developmental defects. Includes government, industry, or academic assays, studies and assessments.
Biochemical or cellular level changes	0.3	the ability to affect the body at a cellular or biochemical level that may have larger, but poorly understood health implications.
Ecotoxicology	0.2	linked to toxicity of wildlife that may include fish, wildlife, plants, or other wild organisms.
Occupational hazards	0.2	linked to hazards for workers exposed on the job, including acute dangers from chemical handling, or longer term health effects from routine occupational exposures.
Irritation (skin, eyes, or lungs)	0.1	linked to irritation of the skin, eyes, or lungs according to government assessments, industry reviews, and peer-reviewed studies.

We assigned numeric hazard scores for each scoring category based on judgment of the relative importance of each with respect to potential health concerns. These scores were informed by a number of factors, including the weight of the evidence associated with each scoring category (e.g. whether the chemical categorization derived from a full government assessment or from a single peer-reviewed study), and by other hazard classification systems, such as the Nordic Substances Substances Database.

For most types of hazards, we assign scores as a function of the lowest known harmful dose where that information is available, the weight of the evidence (limited, moderate, and strong evidence), and the source of the data (individual study; literature review, industry review panel, or major government study; and comprehensive government assessment). We use the scores shown below in our calculations of final hazard (concern) scores for ingredients and products, as described in subsequent sections. The tables below detail the hazard scoring system.

Table 2
Hazard scoring framework for cancer, developmental and reproductive toxicity, endocrine disruption, immunotoxicity, and multiple organ system toxicity

The scores we assign for these hazard categories range from a maximum of 100 for chemicals known to be toxic to humans in a given category as determined by a definitive government assessment, to 20 for chemicals showing limited evidence for toxicity in a non-academic review, down to 0 for chemicals determined not likely to be human toxicants.

Hazard score category	Data source	Hazard Score
Known human toxicant	Government assessment	100
Possible human toxicant	Government assessment	55
Limited evidence of human toxicity	Government assessment	30
Strong evidence for human toxicity	Literature review, industrial panel, or major government study	55
Moderate evidence for human toxicity	Literature review, industrial panel, or major government study	30
Limited evidence for human toxicity	Literature review, industrial panel, or major government study	20
One or more animal studies show effects at very low doses	Individual scientific or peer-reviewed study	30
One or more animal studies show effects at low doses	Individual scientific or peer-reviewed study	20
One or more animal studies show effects at moderate doses	Individual scientific or peer-reviewed study	10
One or more animal studies show effects at high doses	Individual scientific or peer-reviewed study	5
Not likely to be a human toxicant	Government assessment, literature review, industrial panel, or major government study	0

Table 3
Hazard scoring framework: mutations

We assign scores for mutation data essentially the same as for other hazard classifications (as in Table 2), but make modifications to account for the unique range of tests available to define mutation, as shown in this table. Scores we assign for mutation range from 100 for a known mutagen as determined by a definitive government assessment, to 10 for ingredients for which one or more studies on micro-organisms show positive mutation results to 0 for ingredients determined not likely to be mutagens in humans based on a definitive government review.

Hazard score category	Data source	Hazard Score
Known mutagen	Government assessment	100
Possible mutagen	Government assessment	55
Strong evidence for mutagenity in human cells	Literature review, industrial panel, or major government study	55
Moderate evidence for mutagenity in human cells	Literature review, industrial panel, or major government study	30
Limited evidence of mutagenity in human cells	Government assessment	30
One or more studies on mammalian cells show positive mutation results	Individual scientific or peer-reviewed study	30
Limited evidence of mutagenity in human cells	Literature review, industrial panel, or major government study	20
One or more studies on non-mammalian cells show positive mutation results	Individual scientific or peer-reviewed study	20
One or more studies on micro-organisms show positive mutation results	Individual scientific or peer-reviewed study	10
Not likely to be a mutagen	Government assessment, literature review, industrial panel, or major government study	0

Table 4
Hazard scoring framework: biochemical and cellualar level changes

We assign scores for biochemical and celluar level changes where the human health impact may be unclear. The framework is essentially the same as for other hazard classifications (as in Table 2) with some modifications to account for the unique range of tests available to define biochemical changes and because more significant reviews generally are undertaken only on concrete human health effects. Scores we assign for biochemical and cellular level changes range from 100 for a reactive oxygen species that are beginning to be linked up to definitive health effecdts to 5 for ingredients for high dose studies showing biochemical changes.

Hazard score category	Data source	Hazard Score
Produces excess reactive oxygen species that can interfere with cellular signaling, cause mutations, lead to cell death and may be implicated in cardiovascular disease.	Individual scientific or peer-reviewed study	100
Interferes with gene expresion	Individual scientific or peer-reviewed study	30
One or more animal studies show effects at very low doses where the human health implications are not yet well understood	Individual scientific or peer-reviewed study	30
One or more animal studies show effects at low doses where the human health implications are not yet well understood	Individual scientific or peer-reviewed study	20
One or more animal studies show effects at moderate doses where the human health implications are not yet well understood	Individual scientific or peer-reviewed study	10
One or more animal studies show effects at high doses where the human health implications are not yet well understood	Individual scientific or peer-reviewed study	5

Table 5
Hazard scoring framework: Assigning categories based on the Nordic Substances Database hazard potency framework

New to the third update of Skin Deep (May 2007) is a scoring framework to account for detailed toxicity study findings we have folded into Skin Deep from the variety of databases available to us, and over 6000 peer reviewed references.

We assign hazard scores to each recorded lowest toxic dose according to weighting factors used in the Nordic Substances Database classification system, as shown in Table 5. No attempt was made to evaluate the length of time or dosing regimen (such as differentiating between chronic and sub-chronic studies) for repeat doses or accounting for route of exposure. In cases of acute studies where the LOEL instead of the LD50 was reported, the doses were multiplied by a factor of 10.

Potency	Acute Studies1 (LD50 — mg/kg of body mass)	Repeat Dose Studies2 (LOAEL — mg/kg day of body mass)
Very highly toxic — very low dose	<25	<2.5
Highly toxic — low dose	25≤Dose<200	2.5≤Dose<20
Moderately toxic — moderate dose	200≤Dose<2000	20≤Dose<200
Low toxicity - high dose	Dose≥2000	Dose≥200

1. LD50 refers to the chemical dose at which 50% of the animals died.
2. LOAEL is the Lowest Observed Adverse Effect Level which is the lowest dose of a chemical at which a harmful effect is observed in a lab animal.

Table 6
Hazard score framework: Occupational hazards

Potency	Occupational 8 hr TLVs and PELs (mg/m3)
Very highly toxic — very low dose	<3.47
Highly toxic - low dose	3.47≤Dose<27.9
Moderately toxic - moderate dose	27.9≤Dose<279
Low toxicity — High dose	≥279

Note: We derived the occupations exposure factors shown above by converting the animal study doses define potency in the Nordict Substances Database (see Table 6) into equivalent concentrations in workplace air assuming a 70 kg male, 15 breathes/minute, 0.7 liters/breathe over an 8-hour workday.

Table 7
Hazard score framework: Violations of government or industry restrictions or guidelines

Scores in this category range from a maximum of 100 for a violation of a ban to 1 for caustic chemicals used as a pH balancer in a specific product.

Finding	Data source	Hazard Score
Banned or found unsafe for use in cosmetics	Government assessment	100
Violations of restrictions and safety warnings	Government assessment	90
Not safe in cosmetics for specific use	Literature review, industrial panel, or major government study	40
Safe use with an industry determined concentration limit	Literature review, industrial panel, or major government study	25
Safe use with specific consumer instructions	Literature review, industrial panel, or major government study	10
Safe use as a pH adjuster	Literature review, industrial panel, or major government study	1
Approved for use	Government assessment, literature review, industrial panel, or major government study	0

Table 8
Hazard score framework: persistence and bioaccumulation

Because many chemicals are found to persist in the environment and bioaccumulate in organisms and people, chemicals in this category are potentially harmful to both humans and people. Because so many different lists abound, we restrict scores to designations where an authoritative body has found the chemical to be hazardous to humans and where it suspects it might be hazardous to humans or wildlife.

For the hazard score category titled "Ingredients not fully identified," we assign a score of 100, flagging ingredients with unknown identity, such as fragrance and unidentified essential oils.

Finding	Level of finding	Hazard Score
Persistent, bioaccumulative in wildlife and humans	Government assessment	100
Persistent, bioaccumulative in wildlife	Government assessment	50

Table 9
Hazard score framework: multiple exposure routes

Finding	Level of finding	Hazard Score
Used in food or as an additive with limited or no toxicity information available	Government assessment	100
Contaminant in tap water	Government assessment	100
In other consumer products besides personal care products	Government assessment	50
High production volume chemical	Government assessment	50
Environmental releases by industry	Government assessment	50
Used as an inert ingredient in pesticides	Government assessment	50
Designated as safe for use in food	Government assessment	0

Adjusting hazard scores for skin absorption potential

In the penultimate step for deriving product and ingredient hazard scores, we adjust preliminary scores to account for increased potential for an ingredient to penetrate the skin. Currently, we take into account the potential enhanced absorption of a product stemming from the presence of penetration enhancers, and known or potential nano-scale ingredients.

For nano-scale and potentially nano-scale ingredients, the ingredient scores are scaled as in Equation 3 with scaling factors of 1.5 and 1.25, respectively. The overall product scores are not adjusted. In cases where the skin absorption potential is lowered, we also scale downwards for the individual ingredients. Scores are multiplied for 0.5 for reduced or limited absorption, and 0.25 where the ingredient has been shown not to absorb into intact skin. Only for ingredients shown not to absorb into intact, damaged, infant, and thinner skin, is the factor reduced to 0.

Data gap ratings

New to the May 2007 release of Skin Deep is a data gap rating that gives site users a measure on the availability of safety data for any particular ingredient or product. A hazard rating of "low concern" (shown as a green circle in Skin Deep) might be rated in that category because of definitive data proving its safety, or because of a near absence of any safety studies that would illuminate hazards. The data gap rating helps site users know the difference, and to buy products with low hazard concerns backed up by safety data, if they choose. The data gap score was derived from the data availability factors detailed below.

Table 10
DATA GAP RATINGS BASED ON LEVEL OF SOURCE

Different sources are more or less thorough in terms of acquiring or evaluating data. A scientific study uses and weighs the available data based on the listed authors knowledge and experience. In contrast, government assessment panels are comprised of multiple experts and must conduct an expansive literature review.

Data source (weight of evidence)	Data availability factor
Innocuous	100
Government assessment	80
Literature review, industrial panel, or major government study	60
Individual scientific or peer-reviewed study	30

Table 11
DATA GAP RATINGS BASED ON FINDING

For assessments and reviews, the panel or reviwer usually expresss the findings based on the weight of evidence. Not only do these different findings have different implications for regulations, they inherently imply the certainty of the experts in their overall finding. Known assessments express no doubt, while possible toxicants or weak evidence express greater doubt.

Finding	Certainty of finding
Known toxicant	100
Probable toxicant or strong evidence	75
Possible toxicant or moderate evidence	50
Limited evidence	25
Unassessed or unknown	0

In the case of data drawn from individual studies in the peer reviewed literature, rather than attempting to weight the uncertainty inherent in the study itself, the conclusions of such studies are assigned a constant certainty factor of 30% to represent the fact that they do not carry the same weight as a full-blown government assessment of hazard.

We excluded data on violations and data on other sources of human exposure from the uncertainty metric, because these are not measures of toxicity. We also counted and considered the number of studies that are available in PubMed for each ingredient by an automated querying system that looked for synonyms or, where available, the CAS registry number along with studies focusing on toxicity (such as but not limited to cancer, sensitization, liver toxicity, dermal penetration, etc. We hypothesized that greater numbers of studies in Pubmed for a particular ingredient was likely to increase the odds that government and industry toxicity and regulatory databases accurately reflects information on the ingredient's toxicity. The Pubmed category contributed 10% to the overall uncertainty and was scored as described in Table 12.

Table 12
DATA GAP RATINGS BASED ON NUMBER OF STUDIES IN PUBMED

Number of studies available for a particular ingredient	Certainty factor
0	0
>0 and <10	1
≥10 and <25	2
≥25 and <50	3
≥50 and <100	5
≥100 and <250	8
≥250 and <1000	9
≥ 1000	10

Finally, where government, industry, or an academic identified data gaps in their reviews, we reduced the certainty of all reviews and assessments for that ingredient by 50%.

At the ingredient level, uncertainty was determined by:

where C_category is the certainty associated with a particular score category and ^w is the weight of the category. We chose to square certainty, rather than uncertainty to reduce uncertainty in cases where the hazards of a product are known.

At the product level,

where n is the number of ingredients and U_n is the uncertainty associated with a particular ingredient.

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