Human health exposure from contaminated land: A LQM/CIEH report
James Lymer
Wardell Armstrong LLP
ECG Bulletin July 2015
Wardell Armstrong LLP
ECG Bulletin July 2015
Since 2002, the Environment Agency has used the Contaminated Land Exposure Assessment (CLEA) model to determine soil guideline values, which are soil concentrations that represent a minimal risk to human health (1). A recent report by Land Quality Management (LQM) and the Chartered Institute for Environmental Health (CIEH) provides an updated assessment of suitable for use levels in soils (S4ULs) for 89 substances (2).
LQM/CIEH previously published two editions of Generic Assessment Criteria (GAC) in 2006 and 2009, respectively. These GAC complemented the available SGVs produced by the Environment Agency (EA) from 2002 onwards. Few Soil Guideline Values (SGVs) have been produced by the EA and there is little indication that further values will be published in the near future. Since the 2009 edition of the LQM/CIEH GAC report, several changes have occurred in the contaminated land risk assessment sector. First, various revised values for exposure, toxicology and physicochemical parameters have been adopted in the UK. Secondly, in December 2013, DEFRA produced Category 4 Screening Levels (C4SL) for assessment of land affected by contamination (3). This approach included new exposure land uses for public open space, suggested modifications to the exposure parameters, and set the toxicity value at low risk rather than the minimal risk adopted in the derivation of other GACs.
Considering the above developments, LQM/CIEH published a report on Suitable 4 Use Levels in January 2015 (2). An S4UL is a soil concentration that represents a minimal risk to long term human health. The methodology for deriving the S4ULs is based on a modified version of the Environment Agency CLEA model (1). The S4ULs were derived using an iterative approach including modification of the exposure parameters in the CLEA model. The toxicology input (health criteria values) is an estimated contaminant concentration that would pose a tolerable or minimal risk to human health and is a lower level of risk than that used to derive C4SLs. The health criteria values were selected in accordance with Environment Agency guidance (1), which was used in the derivation of previous GACs and the SGVs. The S4UL derivation included updated contaminant toxicology input values, fate and transport properties and exposure parameters, such as the vapour inhalation rate as updated by the United States Protection Agency in 2011. The report includes suitable-for-use levels (S4UL, a type of GAC) for 89 substances including metals, total petroleum hydrocarbon fractions (aromatic and aliphatic), polycyclic aromatic hydrocarbons, and chlorinated hydrocarbons. The S4UL values were derived for six generic land uses: residential with and without home-grown produce, commercial, allotments, and public open space as parks and as land adjacent to residential dwellings.
For example, benzo[a]pyrene is a proven human carcinogen and is classed as a non-threshold contaminant. To obtain the S4UL, the CLEA model is used to estimate the average daily exposure from benzo[a]pyrene in soil, which is equivalent to its toxicity value. This is reported as a soil concentration that represents a minimal risk to long term human health, that is, a S4UL. Further details on the derivation and application of these assessment criteria are presented in (2) and in the CLEA framework reports.
References
1.Environment Agency, CLEA Reports, see https://www.gov.uk/government/collections/land-contamination-technical-guidance
2.LQM/CIEH, 'Suitable 4 Use Levels' http://www.lqm.co.uk/publications/
3.DEFRA, SP1010 – Development of Category 4 Screening Levels for assessment of land affected by contamination, updated in September 2014.
Previous ECG Bulletin articles on contaminated land may be found in the July 2008 (pp. 18-20), January 2010 (p. 36) and July 2014 (p. 4 and p. 21) issues, see http://www.rsc.org/Membership/Networking/InterestGroups/Environmental/bulletin.asp.
LQM/CIEH previously published two editions of Generic Assessment Criteria (GAC) in 2006 and 2009, respectively. These GAC complemented the available SGVs produced by the Environment Agency (EA) from 2002 onwards. Few Soil Guideline Values (SGVs) have been produced by the EA and there is little indication that further values will be published in the near future. Since the 2009 edition of the LQM/CIEH GAC report, several changes have occurred in the contaminated land risk assessment sector. First, various revised values for exposure, toxicology and physicochemical parameters have been adopted in the UK. Secondly, in December 2013, DEFRA produced Category 4 Screening Levels (C4SL) for assessment of land affected by contamination (3). This approach included new exposure land uses for public open space, suggested modifications to the exposure parameters, and set the toxicity value at low risk rather than the minimal risk adopted in the derivation of other GACs.
Considering the above developments, LQM/CIEH published a report on Suitable 4 Use Levels in January 2015 (2). An S4UL is a soil concentration that represents a minimal risk to long term human health. The methodology for deriving the S4ULs is based on a modified version of the Environment Agency CLEA model (1). The S4ULs were derived using an iterative approach including modification of the exposure parameters in the CLEA model. The toxicology input (health criteria values) is an estimated contaminant concentration that would pose a tolerable or minimal risk to human health and is a lower level of risk than that used to derive C4SLs. The health criteria values were selected in accordance with Environment Agency guidance (1), which was used in the derivation of previous GACs and the SGVs. The S4UL derivation included updated contaminant toxicology input values, fate and transport properties and exposure parameters, such as the vapour inhalation rate as updated by the United States Protection Agency in 2011. The report includes suitable-for-use levels (S4UL, a type of GAC) for 89 substances including metals, total petroleum hydrocarbon fractions (aromatic and aliphatic), polycyclic aromatic hydrocarbons, and chlorinated hydrocarbons. The S4UL values were derived for six generic land uses: residential with and without home-grown produce, commercial, allotments, and public open space as parks and as land adjacent to residential dwellings.
For example, benzo[a]pyrene is a proven human carcinogen and is classed as a non-threshold contaminant. To obtain the S4UL, the CLEA model is used to estimate the average daily exposure from benzo[a]pyrene in soil, which is equivalent to its toxicity value. This is reported as a soil concentration that represents a minimal risk to long term human health, that is, a S4UL. Further details on the derivation and application of these assessment criteria are presented in (2) and in the CLEA framework reports.
References
1.Environment Agency, CLEA Reports, see https://www.gov.uk/government/collections/land-contamination-technical-guidance
2.LQM/CIEH, 'Suitable 4 Use Levels' http://www.lqm.co.uk/publications/
3.DEFRA, SP1010 – Development of Category 4 Screening Levels for assessment of land affected by contamination, updated in September 2014.
Previous ECG Bulletin articles on contaminated land may be found in the July 2008 (pp. 18-20), January 2010 (p. 36) and July 2014 (p. 4 and p. 21) issues, see http://www.rsc.org/Membership/Networking/InterestGroups/Environmental/bulletin.asp.
