RIVM, The Netherlands
The risk assessment of a substance that is contained in multiple consumer products requires estimation of the aggregate exposure from all products combined. It is advised that the assessment of aggregate consumer exposure follows a tiered approach. Typically, such a tiered approach starts with a deterministic assessment in which single product exposure estimates are added up. If needed, the assessment is refined in higher tiers by accounting for more detailed information on exposure factors, such as co-use information and product composition information, including presence probabilities. This tiered approach to aggregate exposure assessment is illustrated in the case of phenoxyethanol in cosmetics, personal care and household products.
For phenoxyethanol in cosmetic products, as a first tier, the deterministic method to estimate aggregate exposure proposed in (SCCS, 2012) is used. Subsequently, the aggregate exposure evaluation is refined in a second tier, using two different person-oriented exposure models, the Creme Care & Cosmetics and PACEM models. In the second tier assessment, progressively more information on co-use of products and data on product composition is incorporated.
For household products, the contribution to aggregate exposure from different sources is estimated using the AISE REACT tool. As no higher tier method is currently available, the assessment was not further refined.
The case illustrates how existing tools may be used to refine aggregate exposure assessment using progressively more information. Higher tier assessments usually lead to reduced estimates of exposure, while still being protective for the population. On the other hand, higher tier assessments require more effort and data; data which is usually scarce or absent altogether. A particularly important data gap in practice, is the information on substance concentrations in consumer products.
During the discussion, the need to justify choices and document the principals of why certain tools and models are used over others was highlighted. The basic premise is that it is not realistic to assume that consumers use all the products all at the same time, so adding a higher tier adds value and enables more realistic assessments.