Exposure Assessment
Tier 0
Exposure Sources
Triclosan is commonly used as an antibacterial and antifungal agent in a variety of applications in personal and medical care products. It generally comes in the form of a white powdered solid with a slight aromatic odour and is only slightly soluble in water. Common uses of triclosan in and personal products include antibacterial soap, mouthwashes, toothpastes, deodorants, shampoos, and it is also used as a preservative in cosmetics. Other uses include cleaning supplies, toys, bedding, socks, bin liners, textiles, carpets, and plastics.
Triclosan has been added to the surface of cutting boards, food storage containers and other kitchen utensils to stop microorganisms growing on them. However, since March 2010, triclosan cannot be used in the EU in food contact materials or as an additive in plastics that come into contact with food. Triclosan is not used as a disinfectant in food and feed production and it is not approved as a food preservative in Europe. It is also used in biocidal products for veterinary hygiene but it is banned as a preservative in animal food.
Owing to its uses, the primary routes of exposure to triclosan in consumers are via the oral (e.g. toothpaste and mouth wash) and dermal routes (e.g. personal care products and cosmetics), which will be the focus of the subsequent analysis.
Tier 1
The starting point for the exposure assessment is based upon an SCCS opinion on triclosan, which uses the exposure scenarios in the SCCS notes of guidance for consumer exposure assessment to personal care products and cosmetics (SCCS, 2012), and assumes two concentration levels:
- A maximum EU regulatory use level of 0.3% in all categories
- A combination of the maximum use level at 0.3% and typical use levels of 0.15% and 0.2% in different categories
In accordance with the SCCS notes of guidance, the assessment uses standard exposure scenarios, and aggregation across products is performed via deterministic summing of individual product exposures. These amounts are upper estimates of product use, based upon the 90th percentile of product use in each individual category using values derived from previous studies performed by the cosmetic trade association, which at the time was called Colipa, but is now called Cosmetics Europe (Hall et al, 2007, 2011). The product categories considered are listed in Table 3, along with the relevant exposure parameters relating to retention factor and dermal absorption:
Table 3: SCCS Exposure Values and Dermal Absorption Estimates for Triclosan
| SCCS Product | Retention Factor | Dermal Absorption (%) |
| Toothpaste | 0.17 | 100 |
| Mouthwash | 0.1 | 100 |
| Deodorant Stick | 1 | 7.7 |
| Body Lotion | 1 | 13.3 |
| Hand Soap | 1 | 7.2 |
| Shower Gel/Body Soap | 1 | 7.2 |
| Face Powder | 1 | 11.3 |
| Blemish Concealer | 1 | 11.3 |
In the original study, the dermal penetration value is calculated using a value of flux for a given concentration, measured in µg/cm2. This was used to estimate the percentage dermal penetration, reported in the above table. Aggregate exposure was calculated by deterministically summing the individual product exposures for assumed exposure amounts, giving rise to the following estimates of systemic exposure (Table 4):
Table 4: Total aggregate exposure estimates to triclosan in European consumers calculated assuming a maximum EU regulatory use level of 0.3% in all categories
| SCCS Product | Estimated Absorbed Dose
(mg/kg bw/day) |
| Toothpaste | 0.0234 |
| Mouthwash | 0.15 |
| Deodorant Stick | 0.0015 |
| Body Lotion | 0.1646 |
| Hand Soap | 0.0066 |
| Shower Gel/Body Soap | 0.0268 |
| Face Powder | 0.0060 |
| Blemish Concealer | 0.0006 |
| Total Aggregate Exposure | 0.3795 |
A similar assessment was performed, where marginal-use products (mouthwash, body lotion, face powder, and stick concealer) were assigned concentrations ranging from 0.15-0.2%, giving rise to the values shown in Table 5.
Table 5: Total aggregate exposure estimates to triclosan in European consumers calculated assuming a combination of the maximum use level at 0.3% and typical use levels of 0.15% and 0.2% in different categories
| SCCS Product | Estimated Absorbed Dose
(mg/kg bw/day) |
| Toothpaste | 0.0234 |
| Mouthwash | 0.1000 |
| Deodorant Stick | 0.0015 |
| Body Lotion | 0.0823 |
| Hand Soap | 0.0066 |
| Shower Gel/Body Soap | 0.0268 |
| Face Powder | 0.0040 |
| Blemish Concealer | 0.0003 |
| Total Aggregate Exposure | 0.2449 |
The assumptions in this method of exposure assessment, whether implicit or explicit, are:
- Triclosan is present in every product category all the time
- Triclosan is present at a maximum or combination of maximum and usual use levels (therefore no variability in concentrations are considered)
- Every consumer uses every product category at a high use level
- Exposure (and therefore risk) is the same for every subpopulation of consumers
The exposure assessment is conservative by design, and offers many advantages such as allowing a quick and simple assessment of risk to be determined. However, in the event that exposure is considered to be unacceptably high, a refined assessment exposure (rather than a risk management measure) is the next logical step in order to provide a more accurate determination of aggregate consumer exposure.
Tier 2
A number of refinements are possible when performing a higher-tier exposure assessment, by examining the various factors driving the conservative nature of a screening level type exposure assessment. Given that a number of refinements are possible and that time and resources are often scarce for the risk assessor, a logical question to ask is what are the relative impacts of the different refinements that can be achieved? Having an idea of this can in turn help with deciding where to focus resources when performing a refined exposure assessment.
Creme Care & Cosmetics
Aggregate exposure assessments were calculated with the Creme Care & Cosmetics model. This is a probabilistic exposure model and software for determining high-tier estimates of aggregate exposure to substances in personal care products and cosmetics. It is built upon a habits and practices database of over 36,000 consumers from a product use survey developed by Kantar Worldpanel for Europe and the United States, detailing frequency of product use, co-use and site of application for 25 product categories over a seven-day period. Amount per application data is based upon clinical studies for the same products, which are in the form of statistical distributions. Additional required parameters for exposure estimates such as bodyweight, height and skin surface areas are also included in the form of statistical distributions from published sources (e.g. NHANES) and standard calculations (e.g. the Dubois formula). The model calculates aggregate exposure to a chemical via the dermal, inhalation and oral routes, with systemic exposure expressed on an absolute or per unit bodyweight basis and dermal exposure as per unit of skin surface area by site of application.
The model works by combining data on the concentration of a substance within each product category with the data in the habits and practices database. Concentration values can be point estimates or statistical distributions, described empirically or parametrically, and with or without presence probabilities (i.e. the likely occurrence in each product category). Daily exposures are simulated for each individual consumer based on selected inputs, which are used to calculate distributions of chronic or acute exposure in the population being assessed, which can be stratified by age, gender, or geography. The calculated exposure distribution (described using the appropriate measure to compare with the reference dose in question) is in turn described using appropriate statistics, and can be broken down to assess the relative contribution of each product category to exposure, or alternatively to assess the relative magnitude of the exposure at each application site.
The model is accessed via a secure cloud computing software application, which allows for computation on the large accompanying data sets and multiple iterations of Monte Carlo simulations as required.
Three scenarios were considered:
- Triclosan always present, concentration = 0.3% (max authorised)
- Using triclosan presence probabilities, concentration = 0.3% (max authorised)
- Using triclosan presence probabilities, concentration at current use (0.15% - 0.3 %)
In order to have a like-with-like comparison with the SCCS notes of guidance and to examine the impact of various refinements, retention and penetration factors were kept consistent with the original assessment. The product categories in the SCCS assessment were in turn matched with the product categories in the Creme Care & Cosmetics model, which are based upon those that were in the original Kantar Worldpanel survey.