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  1. A regulatory perspective Raquel Duarte-Davidson WHO Collaborating Centre, Cardiff University Chemical Hazards and Poisons Division (CHaPD), HQ, Chilton SHE-Net workshop 2nd and 3rd of July 2008, Nottingham University

  2. Problem Formulation * Stages with each tier of Risk Assessment Hazard Identification Risk Prioritisation Tier 1 Risk Screening * Exposure Assessment Tier 2 Generic QuantitativeRisk Assessment * Risk Estimation Tier 3 Detailed QuantitativeRisk Assessment * Risk Characterisation Options Appraisal Economics Technology Social Issues Management Risk Management Collect data, iterate processes & monitor What do we Mean by a Tiered Approach to Risk Assessment?

  3. What Determines How Sophisticated A Risk Assessment Should Be? • Size and characteristics of environmental release • Nature of population exposed • Availability and quality of input data • Expectations of stakeholders (regulatory, public etc) • Utilisation of output

  4. B B Appropriate Selection of Risk Assessment Methodologies A, B and C represent hazards requiring assessment Line of Acceptability of risk Quantitative Increasing Resolution, Sophistication and Cost Generic-Quantitative C Qualitative B A C Increasing Risk (log scale)

  5. Screening and Prioritisation An Example Exposure screening to determine risks to public health from F&M disposal options • Environment Agency’s contribution: to undertake rapid qualitative environmental exposure assessment • This (and other information) was used by the Department of Health to produce a preliminary shortlist of potential risks from the different disposal options and inform policy • Further details from:http://www.dh.gov.uk/PublicationsAndStatistics/Publications/

  6. Qualitative Screening and Prioritisation • Preliminary shortlist • two disposal options (burial, pyre) • 13 hazards/groups • reduced number of pathways (one to 4 per hazard/group) • Screening: • five disposal options (rendering, incineration, landfill, pyre burning, burial) • source -pathway -receptor analysis • >100 hazards (biological/chemical) • multiple pathways (up to 20 pathways per hazard per disposal option) • More detailed assessment if required

  7. Existing preventive measures? Hazard Release Exposure Pathway Likelihood of exposure Population exposed Public health consequences Frompyre burning; released over long time scales Inhalation, deposition and incorporation in food Slight effect by choice of fuels but PAHs will always be present. Advice to local population. Site pyres to avoid residential areas. PAHs (chemical) Low / medium; assumes proximity to site/ outdoors Local population Small risk of lung cancer with prolonged exposure; may not be relevant for increased exposure over only a few days Qualitative Source – Pathway – Receptor Analysis

  8. Disposal option with greatest human exposure to hazards Disposal options entailing some human exposure to hazards Summary of results from the Screening Exercise: Potential Health risks, Disposal Methods and Pathways R = Rendering; I = Incineration; L= Landfill; P = Pyre; B = Burial

  9. More Detailed Risk Assessment An Example Assessing risks from use of incinerator ash as footpath material (Byker Ash) • High dioxin levels reported at a number of sites (footpath ash and surrounding soils) • Sites used for recreational activities (e.g. parks & allotments) • Environment Agency undertook an exposure assessment and produced a briefing note • Part of a wider programme of work (Newcastle City Council and University) • Further details from: • Pless-Mulloli T, Edwards R, Papke O & Schilling B (2001) PCDD/PCDF and heavy metals in soil and egg samples from Newcastle allotments

  10. Approach • Site specific exposure assessment • Conceptual model developed for each site, e.g. allotment, park, measured soil concentrations, critical receptors - e.g. allotment holder, toddler • All potential pathways considered - e.g. eating home grown vegetables, soil ingestion • Computer packages(Risk Human and CalTOX) used to derive a daily intakes • Daily intakes estimated for 6 sites(4 allotments, 1 Park, 1 control) • “Worse case scenario” assumed for each site (e.g. maximum soil concentrations; large proportion of vegetables consumed unwashed & produced in allotments)

  11. Estimated daily intake (pg TEQ/kg bw/day) Site Soil Concentration (ng TEQ/kg) Allotment 1 Allotment 2 Allotment 3 Allotment 4 Control Park/Recreational area 167 81 69 18 11 321 16 9 8 4 3 14 Results • Estimated daily intake includes background intakes (e.g. milk & dairy products, fish) • Work undertaken in 2001; then recommended TDI was 10 pg TEQ/kg bw/day • Estimates in yellow exceed TDI; more detailed exposure assessment may be required to include more realistic estimates of exposure

  12. To Conclude • A structured and tiered approach provides a very valuable and timely method of informing Government and the general population as to the potential risks from different activities • In reviewing existing risk assessment models government departments and agencies are interested in: • Ensuring there is a clear understanding of the site under study and all potential sources, pathways and receptors • Providing a transparent audit trail with justification for screening out pathways where probability of exposure is negligible or low • In identifying key research needs we need to consider the use of both deterministic or probabilistic approaches to ensure that the method used is fit for purpose