The earliest version of the ICRCL guidelines (e.g.
ICRCL 1979) covered only a selected range of elements including lead,
cadmium, and arsenic (see Table 1). Numbers
were provided for "acceptable" concentrations of
contamination, i.e. they were derived on the basis that a soil could
be contaminated but not necessarily pose any significant additional
risk to users of a site - the soil was clean enough for the intended
land use. However, by 1982 the term "trigger value" was
being employed to describe a concentration above which thought should
be given as to whether there were any additional risks and whether
any remedial measures should be carried out (Smith 1982). Values were
originally provided for four different land uses (later reduced to
two) - see Table 1. The differentiation was
made on the basis of presumed different exposures by site users,
particularly children, and the different routes of exposure presented
by the different land uses, particularly the likelihood of
consumption of vegetables grown on the site.
The orignal numbers were assembled by the then
Secretary of the ICRCL (M A Smith) from a number of sources including:
site-specific risk assessments made for cadmium in the UK,
work by the Greater London Council's Scientific Branch
to develop trigger concentrations,
established guidelines for the disposal of sewage
sludge to agricultural land,
statutory limits on lead and certain other elements in
toys and graphic materials,
various literature sources including accounts of
site-specific assessments and judgements that had been made,
established guidance on the assessment of the
phytotoxicity of zinc, copper and nickel.
In the early versions of the guidelines the thinking
that had gone into them was explained and the value for a number of
elements discussed in detail.
The early versions were circulated widely for comment.
In practice, although there was substantial discussion of principles,
the numbers themselves were never seriously challenged. Such changes
as were made in the values, were made in the light of additional
information as it became available. Although the values for cadmium
and lead were subjected to detailed review (Simms & Beckett
1987), this did not result in any changes.
Extension to Embrace Coal Carbonisation Sites
In 1979 a contract was placed with AEA Harwell
Laboratory to make a detailed audit of the coal carbonisation
industry - to identify the nature of contamination that could arise
and the hazards it could pose. The report, later revised (DOE 1987),
included proposals for two trigger values for a range of contaminants
typical of coal carbonisation sites, including polycyclic
aromatic hydrocarbons (PAHs) and phenols, and recognised two
principal land use categories (see Table 1).
The lower, or "trigger threshold value," corresponding to
those existing for lead etc, indicated a need to consider action. The
higher "action trigger value" was set at a concentration at
which there was a presumption that some form of action would be
required. The suggested values were incorporated into the formal
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TABLE 1: SCOPE OF ICRCL GUIDELINES
VERSION (current to 2002)
Land Use Catergories
Large gardens and allotments
Public open space
Domestic gardens and allotments
Parks, playing fields, open space
Domestic gardens and allotments, play areas
Landscaped areas, buildings, hard cover*
Polycyclic aromatic hydrocarbons (PAHs)
* General groupings of categories: some variation with contaminant
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Version Current in 2002
The DOE/ICRCL guidelines in use in
2002 when they were replaced by the existing Soil Guideline Values,
were contained in a document issued in 1987 (ICRCL 1987). This
contained general advice on how contaminated sites should be
approached (e.g. the principles of site investigation) and the way in
which the guidelines should be applied. As can be seen in Table
1, the number of potential inorganic contaminants for which
there were values was reduced in later versions of the guidance.
The values in use immediately
before their formal withdrawal by the Department for Environment,
Food and Rural Affairs (DEFRA) in 2002 can be found elsewhere on the web.
There is also a separate ICRCL
document (ICRCL 1990) dealing with old metalliferous mining sites but
this is not entirely consistent with the main guidance document (see below).
The guidelines suffered from a
number of deficiencies, including:
the limited range of contaminants
covered (see Table 1),
the lack of "action"
values for lead, cadmium etc.,
the failure to take certain risks
to human health into account when setting the values,
the absence of a source document
to which people can refer to find out the basis of the values for
environmental hazards are
generally not taken into account,
potential to affect ground or
surface waters is not covered,
here are no guidelines for
the analytical methods to be
employed are not specified.
Risks to human health not taken
into account (by the author when producing the first versions of the
guidelines) were contact hazards for nickel and the human toxicity of
copper. These elements are only covered in respect of phytotoxicity
(toxicity to plants). These limitations were pointed out in early
versions but are not explicitly stated in the 1987 version.
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Guidance on Old Metalliferous Mining Sites
In 1990 the ICRCL issued separate guidance (ICRCL
1990) on old metalliferous mining sites to be used for agriculture or
similar uses. The document, originally produced by the Agricultural
Development and Advisory Service (ADAS) with input from MAFF, was
endorsed by the ICRCL, without apparently considering whether it was
consistent with the existing guidance. It has resulted in certain
anomalies particularly for example in respect of guidelines for lead
and cadmium (e.g. the trigger value for lead for pasture is less than
that for domestic gardens) . The approach to derivation of the values
was not particularly conservative and the action values have been set
at a level at which there may be overt damage to the health of
livestock. The approach appears to be basically to allow the farmer
to produce rather than to ensure protection of human health or the
environment in the longer term.
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DOE (1987) (Department of the Environment),
"Problems arising from the redevelopment of gas works and
similar sites (second edition), HMSO, London.
ICRCL (1979) (Interdepartmental Committee on the
Redevelopment of Contaminated Land), Acceptable levels of toxic
elements in soils, ICRCL 16/78, Department of the Environment, London.
ICRCL 1987 (Interdepartmental Committee on the
Redevelopment of Contaminated Land), Guidance on the assessment and
redevelopment of contaminated land, Guidance Note ICRCL 59/83 (2nd
edition), Department of the Environment, London UK.
ICRCL (1990) (Interdepartmental Committee on the
Redevelopment of Contaminated Land), Notes on the restoration and
aftercare of metalliferous mining sites for pasture and grazing,
Guidance Note 70/90, Department of the Environment, London UK.
Simms D L and Beckett M J (1987), Contaminated land:
setting trigger concentrations, Sci Total Environ 65, 121-134.
Smith M A (1982), Acceptable concentrations of
contaminants in soils, Proc. Conf. Redevelopment of Contaminated
Land, Woolwich 1981, London Borough of Greenwich, London.
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The Numerical Values & Documentation
The numerical values contained in ICRCL 59/83 (2nd
Edition) can be found at www.zeroenvironment.co.uk/icrcl.htm
The document itself can be found at: www.eugris.info/envdocs/ICRCL59_83.pdf