Aggregate Exposure
Aggregate exposure considers all sources of exposure to a single chemical (e.g. hair care products, cosmetics, detergents, foods, environmental media, etc.) via all routes (oral, dermal, and inhalation). The report focuses on consumer products, and not occupational exposure situations, including the following product domains: cosmetics and personal care products, household products (such as household cleaning products, laundry and dishwashing products, etc.), food and other consumer products (such as surface coatings, adhesives, sealants, disinfectants, automotive care products, toys etc.).
This report identifies sources of exposure data to consumer products, and tools for use in generating exposure estimates. It then focuses on more complex cases where an aggregate exposure assessment is useful, and investigates how this can be done using the new tools that are available. Aggregate exposure assessment may be important to consider when substances are present in a variety of products to which consumers might be regularly exposed.
Consumer exposure assessment covers the general use of household items. Assessments may be done for a general population or a subpopulation, for example a specific age, sex, or state of health. The chemical may be a directly added ingredient in a consumer product, or it may be present as residue in another ingredient. At the high tier, aggregate exposure assessments can be quite complex, due to the wide variety of consumer product types and formulations, and a variation in the behaviour patterns of consumers in populations. For many categories of consumer products representative exposure data including habits and practices data (frequency and amount) as well as chemical formulation data, are generally not available. In these circumstances, exposure assessors rely upon using worse case exposure assumptions or are faced with the need for generating new data.
Currently aggregate exposure is often assessed by simply adding up worst case exposure estimates per each exposure scenario, likely leading to unrealistically high and conservative estimates of exposures. Several consumer exposure models capable of aggregate exposure estimates have been developed in the past for specific areas of consumer exposures and are currently available to assist in exposure modelling, particularly for cosmetics and personal care products (C&PCPs), e.g. ConsExpov.5.0[1] (Delmaar et al, 2005), Creme Care & Cosmetics™ (Creme Global, 2011[2]), Lifeline (The Lifeline Group[3]), Cumulative and Aggregate Risk Evaluation System – Next Generation (CARES NG, 2016[4]) and Stochastic Human Exposure and Dose Simulation or SHEDS (US EPA, 2015[5]). However, guidance is required as to how to perform aggregate exposure estimates, particularly at the higher tier when refinement is required.
Several publications have suggested methods for assessing aggregate exposure leading to more realistic worst case estimates. One example is a publication by Cowan-Ellsberry and Robison (2009), describing an approach for refining aggregate exposure estimates using data on 1) co-use and non-use patterns of product use, 2) extent of products in which the ingredient is used and 3) dermal penetration and metabolism data. Also, CEFIC-LRI completed a project on the estimation of realistic consumer exposure to substances from multiple sources and approaches to validation of exposure models. This involved developing a tiered approach to aggregate exposure assessment including the compilation of a computational platform, able to perform quantitative aggregate exposure assessments for environmental and consumer products, including case studies on decamethylcyclopentasiloxane (D5) and triclosan. The project is documented in an internal CEFIC report, and the case study on D5 is published in Dudzina et al, (2015).
Given these recent methodological developments in assessing aggregate exposure and increasing variety of tools and databases available for different purposes in exposure assessment, the ECETOC Scientific Committee established a task force to identify best practices and provide guidance with respect to the data and methods that might best be applied for different consumer exposure scenarios.
[1] Available at http://consexpo.nl/
[2] Creme Care & Cosmetics: Aggregate Exposure from Real Consumer Data. Available from http://www.cremeglobal.com/products/cosmetics/
[3] LifeLine Software Suite and Compendia available from http://www.thelifelinegroup.org/
[4] Available from http://caresng.org/
[5] Available at http://www2.epa.gov/chemical-research/stochastic-human-exposure-and-dose-simulation-sheds-estimate-human-exposure