Human exposure to substances is a consequence of their presence in the environment. In the case of substances that are used in consumer products and articles, the most direct human exposure occurs as a consequence of consumer use of the products and contact with the articles. Traditionally, estimation of exposure to such substances is usually done focusing on the individual product or article that is the subject of the assessment. Many substances are present in several different types of products or articles (sources) that may be used or come in contact with one same person in the course of time. There is an increasing realization of the need to consider the potential exposure to a substance as a consequence of its presence in multiple sources. This is often referred to as 'aggregate exposure' to a given substance. A recent IHCP -ECETOC Workshop on "Exposure and Risk Assessment of Chemical Mixtures in Consumer Products" recognised the theme of 'aggregate' exposure assessment as an important one posing difficult challenges to researchers and policy makers in the field.
The different sources where a substance is present may be very different and result in very different patterns of exposure. Different exposure routes, time scales, and frequencies are likely to apply depending on the source. Simple approaches of adding up estimated higher end levels of exposure from each individual source are rarely appropriate as they assume unrealistic or even impossible conditions of simultaneous exposure.
The objective of this project is to propose and develop methodologies to estimate human exposure to substances that are present in numerous sources ('aggregate exposure'). The aim is to provide strategies and approaches that allow for quantitative estimations of exposure as realistic as possible. Some specific project deliveries would include:
”¢ Development of guidance and criteria to inform when an aggregate assessment may be required based on a number of factors such as, for example, the nature of the relevant health end point(s), the nature of the different exposure sources, properties of the chemical, exposure routes involved, etc. Tiered approaches should be encouraged.
”¢ Recommendations on the type and quality of data required and the adequacy of probabilistic approaches depending on the data sets. Identification of best suited probabilistic approaches.
”¢ Identification of key data gaps (including data quality issues) and parameters that are likely to have the most influence on the exposure estimation outcomes.
”¢ Development of strategies to contrast the outcomes of exposure estimates with real exposures so that a verification of the models is possible.
”¢ Completion of a range of case studies to illustrate and verify the proposed methodology.
It is expected that the findings will be developed into a peer reviewed publication, following a process that involves stakeholder discussion and presentation at a suitable scientific conference. This project would be expected to complement ongoing European Commission (including IHCP) and other supported activities in the area. The successful research group would liaise with and take account of the findings and outcomes of such other work.