Health risk assessment of major accidents with toxic chemicals for disaster preparedness and response

Health risks of major accidents with toxic chemicals need to be defined by: (i) nature, (ii) number and (iii) severity. (ad i) Health effects are conveniently categorized by nature into local (L)/systemic (S) and immediate (1)/delayed (2) (health effects). (ad ii) Derivation of population responses generally is unfeasible, instead exposure bands can be specified by effect-level. (ad iii) The continuum of health effects should be described in a global disability scale. The 4 D'-scale seems most appropriate: death (D{sub 1}), disability (D{sub 2}), discomfort (D{sub 3}), detectability (D{sub 4}). For use in disaster response health risk specifications should furthermore be: (1) transparent, (2) in line with the overall situational analysis and (3) congruent with mitigation. (-ad 1) Transparency can be improved by selecting one main sign/symptom by effect level for field instructions. (-ad 2) Situational analysis initially involves the source-area (what effect levels are found near the source ) and the outer limits of the effect area (feedback from telephone complaints mostly D{sub 4}). Otherwise, knowledge is needed of the ratio of exposures that lead to consecutive effect levels to assess the overall health impact by interpolation. Finally, the need to recognize high risk situations is emphasized: e.g. data basesmore » with distributions of dispersion constraints (urban areas), penetration potentials into the housing-stock, concentrations of groups at high-risk (over time). (-ad 3) Mitigation is divided into: (a) protection of the public in a threatened area and (b) medical assistance.« less