The results show that daily occupational exposure to CPF may result in accumulation of CPF and/or its metabolites, possibly resulting in adverse effects.

Estimation of dermal exposure in the workplace resulting from contact with contaminated surfaces is important in risk assessment. Models have been developed to describe the process of exposure due to transfer, but for major input parameters--that is, contact area surface and adherence--defaults are used. This study examines the effect of one single-hand press contact and repeated contacts with a contaminated glass plate on both skin area exposed and loading of the skin for three volunteers. A fluorescent whitening agent was used to study the process of exposure and to determine the increase of the area exposed as well as the adherence of the compound to the skin surface after 1 to 12 consecutive contacts by a video imaging technique. In addition, loading of the skin after 12 contacts was compared to loading of a cotton glove monitor with similar hand pressures. The results show that after one single-hand contact only 4 to 16 percent of the total surface of the palm of the hand was exposed, whereas after 12 contacts this was increased to about 40 percent. The efficiency of transfer was < or = 2 percent of the contamination of the surface. The adherence to the skin was 1.07 micrograms/cm2 after 12 contacts and tended to increase non-linearly with increase in contacts. Because defaults of adherence for use in exposure models are generally a factor 500 to 5,000 higher, and the area exposed is assumed to be the total surface of the hand, overestimation of dermal exposure due to a single hand-surface contact in workplaces may occur. Therefore, additional studies on multi-contact exposure scenarios are indicated to adjust defaults for hand-surface transfer processes.

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REACH (Registration, Evaluation and Authorization of CHemicals) requires improved exposure models that can be incorporated into screening tools and refined assessment tools. These are referred to as tier 1 and 2 models, respectively. There are a number of candidate in tier 1 models that could be used with REACH. Tier 2 models, producing robust and realistic exposure assessments, are currently not available. A research programme is proposed in this paper that will result in a new, advanced exposure assessment tool for REACH. In addition, issues related to variability and uncertainty are discussed briefly, and some examples of tier 1 screening tools are presented. The proposed framework for the tier 2 tool is based on a Bayesian approach, and makes full use of mechanistically modelled estimates and any relevant measurements of exposure. The new approach will preclude the necessity to conduct of case-by-case exposure measurements for each chemical and scenario, since the system will allow for the use of analogous exposure data from relatively comparable scenarios. The development of the new approach requires substantial effort in the area of mechanistic modelling, database development and Bayesian statistical techniques. In this paper, the data gaps and areas for future research are identified to help realise and further improve this type of approach within REACH. A structured data collection and storage system is a central element of the research programme and the availability of this type of tool may also facilitate the sharing of exposure data down and up the supply chain. In addition, new data that are stored according to the proposed structure could enable the validation of any exposure model and thus this programme enhances the exposure assessment field as a whole.

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