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

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

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

5. Screening and Prioritisation An Example Exposure screening to determine risks to public health from F&M disposal options ­Environment Agencys 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 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) Preliminary shortlist two disposal options (burial, pyre) 13 hazards/groups reduced number of pathways (one to 4 per hazard/group) More detailed assessment if required

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

8. Summary of results from the Screening Exercise: Potential Health risks, Disposal Methods and Pathways Disposal option with greatest human exposure to hazards Disposal options entailing some human exposure to hazards 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. Results Site Allotment 1 Allotment 2 Allotment 3 Allotment 4 Control Park/Recreational area Soil Concentration (ng TEQ/kg) Estimated daily intake (pg TEQ/kg bw/day) 167 81 69 18 11 321 16 9 8 4 3 14 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