Final Assessment

2. Substance Identity, Properties and Uses

2.1 Substance Identity

Phenol, 5-chloro-2-(2,4-dichlorophenoxy), commonly known as triclosan, is a chlorinated aromatic compound that has functional groups representative of both ethers and phenols. Information on its identity, including names and chemical structure, is presented in Table 2-1.

Table Notes

Abbreviations: AICS, Australian Inventory of Chemical Substances; ASIA PAC, Asia-Pacific Substances Lists; CAS, Chemical Abstracts Service; DSL, Domestic Substances List; ECL, Korean Existing Chemicals List; EINECS, European Inventory of Existing Chemical Substances; ENCS, Japanese Existing and New Chemical Substances; IUPAC, International Union of Pure and Applied Chemistry; NZIoC, New Zealand Inventory of Chemicals; ; PICCS, Philippines Inventory of Chemicals and Chemical Substances; RN, Registry Number; SWISS, Giftliste 1 and Inventory of Notified New Substances; TSCA, US Toxic Substances Control Act

^a From NCI (2011)

2.1.1 Impurities of Human Health and Environmental Concern

Triclosan contains low levels contaminants, specifically polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). PCDDs and PCDFs were the subject of an assessment as part of the Priority Substances List of CEPA 1988. These substances are considered both persistent and bioaccumulative as well as “toxic” as defined under paragraphs 11(a) and 11(c) of CEPA 1988 (Canada 1990). They are therefore considered to be Track 1 substances under the Toxic Substances Management Policy (TSMP) (Canada 1995).

In Canada, triclosan is included on Health Canada’s List of Prohibited and Restricted Cosmetic Ingredients (more commonly referred to as the Cosmetic Ingredient Hotlist or simply the Hotlist), an administrative tool that Health Canada uses to communicate to manufacturers and others that certain substances, when present in a cosmetic, may contravene the general prohibition found in section 16 of the Food and Drugs Act or a provision of the Cosmetic Regulations (Canada 2007). Under Canadian legislation, cosmetics that contain substances that are harmful to the user cannot be sold. The Hotlist restriction for triclosan sets a maximum concentration of 0.03% in cosmetic mouthwashes and 0.3% in other cosmetic products (Canada 2007, Health Canada 2014b). In addition, oral care products containing triclosan with polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) impurities should not exceed 0.1 ng/g (0.1 part per billion [ppb]) for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and 2,3,7,8-tetrachlorodibenzofuran and 10 µg/g (10 parts per million [ppm]) for total other PCDD/PCDF impurities, with no individual impurity greater than 5 µg/g (5 ppm). These limits for PCDD/PCDF impurities are also expected to be respected by manufacturers/licensees of natural health products containing triclosan (NHPID 2015).

Due to the potential presence of PCDDs and PCDFs at trace levels in triclosan, the United States Pharmacopeia (USP) recommends concentration limits for certain impurities in triclosan (USP 2009). For comparison, while there may be variance on the individual impurity limits, the Canadian limits for total PCDD/PCDF impurities (of approximately 10 µg/g) do not exceed the USP recommended limits (totaled as approximately 21.5 µg/g).

The presence of TSMP Track 1 substances in pest control products is managed in accordance with Health Canada’s strategy to prevent or minimize releases, with the ultimate goal of virtual elimination, as described in Regulatory Directive DIR99-03 (PMRA 1999). The relative importance of triclosan as an environmental source of PCDDs is expected to be low compared with other sources on a national scale. These other sources include large-scale burning of municipal and medical waste, production of iron and steel, backyard burning of household waste, fuel burning (including diesel), wood burning (especially if the wood has been chemically treated), electrical power generation and tobacco smoke (Health Canada 2005).

2.2 Physical and Chemical Properties

Triclosan is soluble in water and has low volatility (Table 2-2). It is not expected to volatilize from a water surface, as indicated by its Henry's law constant. It should ionize at environmentally relevant pH values (i.e., pH 6-9 for water bodies in Canada), as indicated by its acid dissociation constant (pK_a) of 8.1.

Table Notes

Abbreviations: Abbreviations: HLC, Henry's law constant; K_d, soil/water partition coefficient; K_oa, octanol/air partition coefficient; K_oc, soil organic carbon/water partition coefficient; K_ow, n-octanol/water partition coefficient; pK_a, dissociation constant; VP, vapour pressure; WS, water solubility.

2.3 Triclosan Use Patterns in Canada

Triclosan is used as a medicinal ingredient in drug products and medical devices such as sutures as well as a non-medicinal ingredient in cosmetics, natural health products and drug products (DPD 2016; LNHPD 2016; 2016 personal communications from the Consumer Product Safety Directorate, Health Canada, to the Existing Substances Risk Assessment Bureau, Health Canada, and 2015 communication from Therapeutic Products Directorate, Health Canada, to Risk Management Bureau, Health Canada; unreferenced). As of December 31, 2014, triclosan is no longer registered in Canada as a pest control product due to voluntary withdrawal from the market (Health Canada’s Pesticide Product Information Database; Health Canada 2014).

2.3.1 Cosmetic Products

There were 322 cosmetic products containing triclosan notified to Health Canada, including skin cleansers (body, face and hands), moisturizers, face and eye makeups, deodorant sticks/sprays, fragrances, tanning products, shaving preparations, bath products, exfoliants, massage products, styling products, and shampoos (2016 personal communication from Consumer Product Safety Directorate, Health Canada, to Existing Substances Risk Assessment Bureau, Health Canada; unreferenced).

According to the Health Canada's Cosmetic Ingredient Hotlist, concentrations of triclosan that exceed 0.3% in all cosmetics (i.e. deodorants, creams, toothpastes, face washes, etc.) or 0.03% in mouthwashes may contravene the Food and Drugs or the Cosmetic Regulations.

2.3.2 Natural Health Products

Triclosan is listed in the Natural Health Products Ingredients Database (NHPID) with a non-medicinal role for use as antimicrobial preservative in natural health products, provided that it does not contribute to the claim of the product (NHPID 2015). Consistent with the concentrations indicated in the Cosmetic Ingredient Hotlist, the NHPID also lists concentrations of triclosan of less than or equal to 0.03% in mouthwashes and 0.3% in topical products and dentifrices as restrictions associated with the use of triclosan in natural health products (Health Canada 2015; NHPID 2015). As a non-medicinal ingredient, triclosan is listed in the Licensed Natural Health Products Database and therefore is present in currently licensed natural health products (e.g., toothpastes, foot gels, acne treatments, body sprays, skin cleansers and lotions) (LNHPD 2016; January 2014 personal communication from Risk Management Bureau, Health Canada, to Existing Substances Risk Assessment Bureau, Health Canada; unreferenced). There are 16 authorized natural health products containing triclosan (LNHPD 2016).

2.3.3 Drug Products

Approximately 118 drug products that contain triclosan with an assigned Drug Identification Number, primarily antiseptic skin cleansers, were listed on Health Canada's Drug Product Database (DPD 2016). Health Canada's antiseptic skin cleanser monograph states that the permitted concentration of triclosan as an active ingredient can range from 0.1% to 1.0% (Health Canada 2006). Triclosan is also present as a medicinal ingredient in some tooth pastes at a maximum concentration of 0.3% and functions as an anti-gingivitis agent (DPD 2016).

2.3.4 Pest Control Products

The Canadian registrants voluntarily discontinued the sale of pest control products containing this active ingredient. Consequently, as of December 31, 2014, triclosan is no longer registered as a pest control product in Canada.

Commercial-class products containing triclosan and their material preservative uses (textiles leather, food contact material such as cutting boards and countertops, paper, plastic and rubber materials), registered under the PCPA as of December 2014, were considered in the assessment report.

2.3.5 Mandatory survey

A survey conducted under section 71 of CEPA requested information on the manufacture, import, use and release of triclosan in a quantity greater than 10 kg and at a concentration of 0.001% w/w or more for the year 2011. Information on triclosan contained in or used to manufacture pest control products was not requested in this survey (Canada 2013). Results from this survey indicate triclosan was not manufactured in Canada in 2011 (Environment Canada 2013). Twenty-nine companies reported importing between 10 000 and 100 000 kg of triclosan to Canada in the year 2011 as either the pure substance or in product and five companies reported exporting between 100 and 1000 kg of triclosan in manufactured products. Twenty companies reported using triclosan to manufacture formulated products. These product manufacturing facilities were located in Quebec, Ontario, Alberta and British Columbia.

An analysis of the reported data (Environment Canada 2013) revealed that formulated products containing triclosan included over the counter drugs, antibacterial soap, and toothpastes, cosmetics such as skin cleansers, make-up, deodorants, skin creams, fragrances, and cleaning products such as general all-purpose cleaners, and general purpose detergents. As mentioned in section 2.3.1, triclosan is also used in moisturizers, tanning products, shaving preparations, bath products, exfoliants, massage products, styling products, and shampoos. Triclosan is also used in dishwashing products (MSDS 2014). From the total quantity of triclosan used in Canada in 2011, 88% was used as antibacterial soaps, skin cleansers, and toothpaste (registered as drugs, cosmetics or natural health products); 6% was used for other reported products types; and for the remaining 6%, the end uses were not identified (Environment Canada 2013).