Dermal exposure to industrial chemicals during work is of major concern in the risk assessment of chemicals. In the current procedures for European legislation, an approach is taken for which experimental data on dermal exposure in workplaces are lacking.

A large project, with four interrelated work parts, was granted by the European Commission (DG Research) in order to overcome large parts of these problems. The four-year project is now half-way and preliminary results are described.

Introduction
In a project funded by the European Commission (RISKOFDERM, QLKA4-CT-1999-01107), scientists from 15 Institutes from 10 European countries work together with the following major aims:
- Develop a validated predictive model for estimating dermal exposure for use in generic risk assessment for single chemicals.
- Develop a practical dermal exposure risk assessment and management toolkit for use by small and medium-sized enterprises (SMEs) and others, in actual workplace situations.

Research goals
To achieve the above-mentioned aims, a research programme comprising four interrelated work parts was formulated:
1) Qualitative survey in European workplaces to obtain an overview of tasks, processes and determinants relevant for dermal exposure.
2) Quantitative survey to obtain detailed data on dermal exposure and determinants in the most relevant tasks and processes.
3) Predictive dermal exposure model (set) using all relevant variables.
4) Risk assessment and management toolkit (on CD-ROM) from data on hazard, dermal absorption, dermal exposure and effectiveness of control measures for use in workplaces.

Results and discussion
For work part 1, it is assumed that dermal exposure, in the right format dimensions, can be extrapolated from one compound to another when it is task-based. This may not hold for every task, so expert knowledge is required to check the assumption for the task under consideration. To obtain these ‘tasks’, Dermal Exposure Operation (DEO) units were defined, with different scenarios per DEO unit. The scenarios that must be defined should be measurable, observable, relevant for exposure modelling, and universal.

Since hygienists in different countries are making observations with respect to dermal exposure and exposure determinants, it was essential to develop an extensive “Questionnaire for on-site surveys”, as well as a detailed “Instruction manual”. Furthermore, the observers needed to be trained in order to get comparable results. Observations are made for ten different scenarios taken in such a way that all DEO units are covered. Pilot studies have been carried out and were reported and discussed/evaluated in order to make appropriate changes for the main studies. On the basis of the evaluation, the questionnaire was adapted to some extent for work part 1, but extensively for use to collect data for work part 2. The questionnaire contains many questions which cover possible exposures as relevant for work part 3 (see later).The main studies have been carried out. The results have to be reported mid 2002.

In work part 2, the state-of-the-art methodology for measuring external dermal exposure has been discussed and choices have been made for the selected scenarios. Each Institute has selected three scenarios in such a way that all DEO units are covered. The methodology varies with the studied scenario. Also in this work part, pilot studies have been carried out, reported and discussed/evaluated with respect to required changes for the main studies. Currently, the main studies are being carried out or are already finished; the results have to be reported late 2002.

Table: DEO units and Scenarios (with compound) that are being studied in work part 2
1 Handling of objects
- Filling (DEGBE)
- Collecting (colophony)
- Maintenance (cyclophosphamide)
- Loading (DEGBE)
- Filling (metal paint)
- Mixing/diluting (cyclophosphamide/metal)
2 Manual dispersion of substance
- Wiping (metal)
3 Dispersion of substance with hand-held tool
- Pouring (cyclophosphamide)
- Spreading with comb (1methoxy-propanol)
- Rolling (styrene)
- Brushing (DEGBE)
4 Spray dispersion of substance
- Spraying (TGIC powder/metal/organometal)
5 Immersion
- Immersing (chromium/organometal)
6 Mechanical treatment (of solid ob-jects)
- Machining (nickel)
- Grinding (chromium)
- Sawing (colophony)

In work part 3, the exposure is considered to occur through three different routes: direct contact, surface contamination, and deposition and impaction. On the basis of a thorough evaluation of the literature on dermal exposure (assessment), some dermal exposure levels were obtained, as well as determinants of exposure, and available approaches for modelling. On basis of this, a framework of theoretical approaches was developed, including 1) processes and tasks, 2) substance and product characteristics and 3) situations and conditions. This information (a list of possibly relevant variables) is essential for the experimental work to be done in the other three work parts. The variableas are divided along the three routes of exposure: 1) Direct contact, 2)Surface contact, and 3) Deposition and impaction.

Model(s) to be developed on basis of the results of work parts 1 and 2 will be validated/benchmarked with experiments in which model results will also be measured, both externally and internally (by biological monitoring) in actual practice for scenarios with a well-chosen, with respect to knowledge on (human) PBPK-modelling and absorption data, solid and liquid compound. Definitive choices for these compounds have not yet been made. Currently, the general model structure has been developed.

In work part 4, the available literature has been analysed for approaches of risk assessment that could be of use for the toolkit development. For this toolkit approaches are developed for hazard, exposure and risk assessment of dermal exposure on basis of label information and MSDSs for the hazard assessment, and on basis of the approach taken in work part 3 for exposure assessment. The risk assessment is carried out for systemically and locally acting chemicals. The risk management (control) section is based on literature information.

For the exposure assessment method an approach is taken that uses all available dermal exposure studies. From this information typical default values for defined scenarios are derived that can be used to assess dermal exposures, which are then corrected using a graded system for the effect of most of the variables indicated by work part 3.

Table: Essentials of the toolkit concept
The toolkit is transparent and easy-to-handle, and should be able to:
- Activate awareness
- Estimate exposure
- Lead to control actions
- Recognise damaging and/or penetrating potential
- Evaluate risks
- Use STOP principle

The draft toolkit will be considered by teams of occupational hygienists and adapted on the basis of the results obtained form an evaluation in practice.

The final outcome will be a toolkit on paper, but also on CD-ROM. The user, who is supposed to be a non-expert, must answer relatively simple questions and will be guided for that, to obtain qualitative scales for the dermal exposure, the concomitant risk and suggestions for possible control measures to deal with the risk. There will be many text blocks with relevant information on the various issues related to skin exposure, dermal penetration and risk of locally acting and systemically acting compounds.

Conclusion
About half way in a complex four year project, the results cannot yet be discussed in appreciable detail in the light of the project aims. At this point in time, it is clear that the numerous partners from distinct parts of Europe are well-committed and that the project is a bit behind schedule.

Partners in the project
1. TNO Chemistry, Zeist, the Netherlands (project co-ordination and lead Institute for WP 3)
2. Finnish Institute of Occupational Health, KRIOH, Kuopio, Finland
3. Health and Safety Executive / Laboratories, Bootle/Sheffield, UK (lead Institute for WP 2)
4. Institute of Occupational Medicine, Edinburgh, UK
5. Institute of Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands
6. National Institute of Working Life, Umea, Sweden
7. Bundesanstalt für Arbeitsschutz und Arbeitsmedizin, Dortmund, Germany (lead Institute for WP 1)
9. Institut National de Recherche et de Sécurité, Nancy, France
9. Instituto Nacional de Saude Dr. Ricardo Jorge, Lisbon, Portugal
10. Occupational Medicine, Turin University, Turin, Italy
11. Miljø-Chemie, Hamburg, Germany (lead Institute for WP 4)
12. FoBiG, Freiburg, Germany
13. Allgemeine Unfallsversicherungsanstalt, Vienna, Austria
14. Bau-Berufsgenossenschaft, Frankfurt, Germany
15. Instituto Nacional de Seguridad e Hygiene en el Trabajo, Seville, Spain