A method for qualitative estimation of the exposure at task level was used and validated with actual measurements in five small factories. The results showed that occupational hygienists were in general the most successful estimators. Plant supervisors and workers handled the estimation method less successfully because of more misclassification of the tasks. The method resulted, in general, in a classification of tasks in four exposure categories ranging from no exposure to high exposure. The exposure categories correlated positively with mean concentrations, but showed overlapping exposure distributions. This resulted in misclassification of the exposure for individual workers when a relatively large interindividual variability in exposure levels within an exposure category was present. The results show that this method can be used for workplace exposure zoning, but that the usefulness of the estimates for epidemiological purposes is not clear-cut and depends strongly on the actual exposure characteristics within a workplace. A combination of the qualitative exposure estimation method together with assessment of the exposure levels by measurements makes a rearrangement of tasks or individual workers possible and could improve the validity of this method for epidemiological purposes.

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INTRODUCTION 1.1 Time travel 1.2 Innovate, risk concept and prevention 1.3 Science and practice 2 THE FURTURE OF SAFETY SCIENCE 2.1 Questions for the future 2.2 Old problems, new jacket 2.2 Challenges, complex production and complicated laws and regulations 2.3 Examples of high-tech-high-hazard sector, language, safety-aversion, and design 2.4 Knowledge, linear models, quantification, tracing scenario developments 2.5 Impact of non-linear models, safety theory and practice 2.6 Education 2.7 Two non-western countries, Pakistan and China 3 DISCUSSION AND CONCLUSIONS REFERENCES

Introduction of the concept of risk within safety science in The Netherlands focussing on the years 1970-1990 Word count: 13.880, clean text ex summary and refs: 11.591 Summary 1. Introduction 2. Materials and methods 3. The period up to 1970: the emergence of the concept of risk 2.1 Operations research 2.2 Reliability engineering 2.3 Risks of flooding 2.4 Risks and nuclear energy 2.5 Risks in process safety 4. The seventies and eighties: quantification of risks in The Netherlands 4.1 The need for a quantitative approach 4.2 The concept of risk in the process and nuclear industries 4.3 Debating quantitative risk analysis in separate disciplines 4.4 LPG integral study 4.5 Quantitative risk analysis as presented in the Dutch "colored books" 4.6 Criticism of quantitative risk analysis 4.7 Risk perception 4.8 Risk-based approach in Dutch occupational safety 4.9 The acceptability of risks 5. The period after 1990: Risk becoming an accepted concept 5.1 Process Safety: quantitative risk analysis methodologies documented in textbook series 5.2 Exposure to: acceptable risk carcinogenic substances: basis for determining an acceptable risk level 5.3 Occupational safety: introduction of the concept of risk inventory and evaluation (RI&E) 6. Discussion and conclusions 6.1 Developments decisive for introducing the concept of risk in safety science in The Netherlands 6.2 Theories, models, and metaphors developed in the considered period (1970-1990) 6.3 Development of quantitative models 6.4 Risk as a new model 6.5 Differences between the introduction of the concept of risk into occupational safety and into process safety 7. Literature