Human Health and Unacceptable Intake

1. Human Health and Unacceptable Intake A presentation to Brownfield Briefing Contaminated Land Risk Assessment September 2009 MRH Consultants Ltd

2. Scope of presentation • Part 2A & ‘unacceptable intake’ • Current position on SGVs & are they any help? • Recurring issues & why they just won’t go away! • What options do LA officers have? MRH Consultants Ltd

3. If the amount of the pollutant in the pollutant linkage in question…..which a human receptor might take in….would represent an unacceptable intake… assessed on the basis of relevant information on the toxicological properties of that pollutant …. Part 2A and unacceptable intake • Table B of Chapter A of Annex 3 - the statutory guidance to Part 2A: conditions for there being a “significant possibility of significant harm” [SPOSH] to human health • SPOSH is the only option for determining land as contaminated land on health grounds… [assuming significant harm isn’t already occurring] • …so unless the LA can demonstrate unacceptable intake, they can’t make progress on health cases at all under Part 2A… MRH Consultants Ltd

4. Soil Guideline Values Environment Agency, Using Soil Guideline Values, Science Report SC050021/SGV Introduction, March 2009 • SGVs are: • scientifically based GAC used to simplify human health risk assessment in context of long-term exposure… • not relevant to controlled waters risk assessment nor to non human receptors such as ecosystems, buildings, domestic pets etc. • They represent “trigger values” – indicators that soil concentrations above SGV concentrations may pose a possibility of significant harm to human health – they are ‘screening tools’ • SGVs do not represent the threshold at which there is SPOSH & do not automatically represent an unacceptable intake in the context of Part 2A MRH Consultants Ltd

5. More clarity than previously about what they are / are not… Useful short-cut provided site conditions & exposure assumptions apply… Are supported by a model which can be manipulated to in other cases… SGVs – some good things & not so good things…. • Not strictly screening criteria – depends on site conditions… • Still too few – what happened to lead, PAHs, asbestos? • Not measures of ‘unacceptable intake’! MRH Consultants Ltd

6. Some interesting features • SOM assumption – 6% • Basis of HCV […unless a ‘policy based’ number applies!] • threshold substances – TDI […at least 50% must come from soil linkage] • non-threshold substances – ID • ELCR of 1 x 10-5 [reliable human data] • MoE – appropriate benchmark & 10,000 UF [animal data] • General default rules: beware – they don’t always apply: • lifetime exposure for cadmium [not 0-6 years for residential & allotments] • estimated intakes compared to specific HCVs – oral, dermal & inhalation intake against oral HCV for nickel MRH Consultants Ltd

7. So do SGVs help? • Erh….. only if: • site soils conform to assumed default in every respect • the exposure scenario is a ‘standard’ one • the pollutant is one for which an SGV has been published • observed concentrations < tolerable / minimal risk levels… So SGVs will help regulators decide when they’ve NOT got SPOSH…… … but that’s not actually the question that Pt2A requires the regulator to answer! MRH Consultants Ltd

8. serious SGV UI? unacceptable increasing risk tolerable / minimal negligible Recurring issues… • Part 2A is concerned only with unacceptable risks – it aims to • deliver a proportionate response • improve efficiency, transparency & consistency in decision-making • remove uncertainty about liabilities for historic contamination • encourage action though the normal development cycle • Best way of delivering objectives is to have a collective view about what constitutes ‘unacceptable intake’… MRH Consultants Ltd

9. serious unacceptable increasing risk SGV UI? tolerable / minimal negligible Why won’t the problem go away? • Because without a firm consensus • we can never get beyond saying … there might be a problem! • the regulator is vulnerable to all sorts of pressures…some less legitimate than others.. • there will always be pressure to react [i.e. further investigate, assess & possibly to remediate] every time we find contaminants in soil > tolerable / minimal risk levels • Not just a Pt2A issue, similar judgments are required to be made under the SFD and ELD… MRH Consultants Ltd

10. serious unacceptable increasing risk SGV UI? tolerable / minimal negligible Implications of continued lack of consensus? • Unnecessary remediation • Reduced regulator confidence & hence slow progress under regime • Inconsistent decision-making • Confusion, delay, ‘blight’ for those in system.. • Reactive rather than pro-active response amongst problem holders • Continued uncertainty in the property market • Less effective role for Part 2A role as a benchmark for planning … MRH Consultants Ltd

11. Defra’s position • There is too much scientific uncertainty….so much so that the ‘authoritative bodies’ cannot advise… • Not simply about ‘numbers’… Scientific uncertainty exists at the minimal / tolerable risk levels too! Agreed! But risk assessment is an inherently ‘numeric process’; if a numerical approach helps to inform estimates of minimal or tolerable risk, why does the same not apply to estimates of unacceptable risk? Defra, Outcome of the Way Forward exercise on Soil Guideline Values, July 2008 Defra, Guidance on the legal definition of contaminated land, July 2008 MRH Consultants Ltd

12. How does the LA know what is ‘marginal’ or ‘reasonable’? Defra’s position…cont. • What constitutes unacceptable intake is a ‘site-specific decision’ to be made by LAs at the time of determination … • …..taking issues such as costs & benefits into account… • LAs need to concentrate on serious contamination and not worry too much about ‘marginal’ cases… • LAs only have to be reasonable…! Estimating exposure is site-specific; deciding what is an unacceptable intake is NOT! Arguable whether, strictly, the statutory guidance allows the regulator to do this at the determination stage! MRH Consultants Ltd

13. What options do LA officers have? • They could: • ask the HPA… • base their ‘judgements’ on those made by other LAs… • shunt the decision further up the internal hierarchy… • Many will simply… Decide an “unacceptable intake” for Part 2A ‘TOO HARD’ BOX MRH Consultants Ltd

14. No - one really knows! But we do know that it involves … Info on human toxicology A ‘policy’ view Monitor What is the answer? Unacceptable Intake MRH Consultants Ltd

15. To conclude…. Report of a meeting convened by the Royal Society of Chemistry’s Toxicology Group, 15th May 2009, “Can toxicologists further define “unacceptable intake” for contaminated land?” MRH Consultants Ltd