ASSESSING THE ENVIRONMENTAL CONSEQUENCE OF POTENTIAL MAJOR ACCIDENTS

1. ASSESSING THE ENVIRONMENTAL CONSEQUENCE OF POTENTIAL MAJOR ACCIDENTS Andrew Hitchings, Policy Advisor, UK Environment Agency

2. WHY? Seveso II, Annex III: “Systematic identification of major hazards …. and assessment of their likelihood and severity”

3. HOW ? Harm Release Exposure dose-response /surrogatestandards fault-tree and event -tree analysis distribution modelling sourcepathwayreceptor sourcepathwayreceptor sourcepathwayreceptor

4. ENVIRONMENTAL RISK ASSESSMENT Conceptual models and source-pathway receptor analysis; risk screening and prioritisation Identify hazard substances dangerous to the environment used at site and describe all aspects of the site and the surrounding environment HAZOP / Fault and event tree analysis Identify initial events that may result in a major accident Reference to relevant environmental criteria Fault and event tree analysis Estimate the frequency/ probability of initial release event occurring Quantify the potential environmental impact following a release Source-pathway receptor analysis Generic / tailored risk assessment with fault and event tree analysis and/or distribution modelling Identify on-site exposure routes following initial release Estimate the likelihood of such environmental impacts occurring Fault and event tree analysis Criteria Description of environmental risk acceptance criteria for a Major Accident To The Environment Identify all risk management measures to manage unacceptable MATTE risks Assess the acceptability/ tolerability of the risks Reference to relevant environmental criteria

5. CHALLENGES (1) • Environment more complicated • Many more receptors • flora, fauna, built environment • More pathways • ground water, surface water, air, land • Different media • water, air, land, soil

6. CHALLENGES (2) • Lack of Dose-Response Data • species level toxicity data at inappropriate end points either NOEC or LC50 • population level standards (Environmental Quality standards) at inappropriate end point • for many dangerous substance/receptor combinations basic lack of data

7. SOLUTION 1 • Major Accidents to the Environment (MATTE) defined in impact terms • “the more extensive the areas and quantities of natural & semi-natural resource damaged, the longer the effects are likely to last, and the more intensive or severe these effects … the more likely event will be regarded as a MATTE” • (NNRs, SSSI, MNRs) >0.5ha (or 10%) adversely affected, >10% of habitat or population adversely affected • (SAC, SPA, Ramsar) >0.5ha (or 5%) adversely affected, >5% of habitat or population adversely affected

8. SOLUTION 2 • Media specific dose-response surrogates • environmental harm doses for dangerous substances to complement human health • precautionary principle • Proportionate Environmental Risk Assessment • focus on technical measures not environmental risk assessment assumptions/methods

9. SOLUTION (?) 3 Increasing chemical concentration LC/EC50 for most sensitive species* LC/EC50 values for other, less sensitive species* EQS or EAL COMAH threshold should lie in this range

10. WHO? • UK Environment Agencies • research into developing environmental doses • EU Challenge • scope for collaboration between member states • industry and competent authorities