Estimation of Fibre concentrationsFibre concentrations were estimated using data collected in experimental studies undertaken by IOM linking soil asbestos content to f/ml per mgm-3 of respirable dust in air (right). A second estimate of f/ml was based on data published by the Dutch research institute RIVM (below-right).

IntroductionAsbestos is turning up in gardens in many pre-1990s housing schemes built on redeveloped land. Asbestos exposure may result from disturbing asbestos-contaminated soil by, for example, gardening or children playing. Councils must decide whether the asbestos contamination represents SPOSH. The Environment Agency has noted that “asbestos is an important contaminant but it is not consistent with the standard CLEA methodology”. This poster describes the use of the Advanced REACH Tool – ART – for estimating exposure.

Asbestos in gardens: assessing the risksAlison Searl, Alastair Robertson, Alan Jones IOM Consulting Ltd www.iom-world.org

Outdoor exposureThe release of fibres from asbestos in soils only occurs when soils are dry. The concentrations of total inhalable dust (mgm-3) predicted by the ART model for gardening or playing in soil for a range of soil textures and conditions are shown below: median (inter-quartile range); respirable dust estimated as 25% total inhalable dust.

Indoor airSoil contamination can be brought indoors on muddy feet and fibres released to indoor air. We spend most of our lives indoors and may be exposed to fibres in indoor air. Measurement data, however, does not indicate that there is substantial transfer of asbestos fibres from garden soils to indoor air.

Risk assessmentThe cancer risk associated with asbestos increases with age at first exposure and the most sensitive receptor is a toddler. The risk assessment was based on a loam soil, a soil asbestos concentration of 0.04%, 90 days exposure to 0.115 mgm-3 respirable dust = 0.0046 fml-1 (ART-IOM model) for

For more information about IOM services in quantitative asbestos in soils analysis (UKAS accredited), investigation of asbestos contaminated sites and quantitative risk assessment for asbestos, contact: alison.searl@iom-world.org

Modelled outdoor exposure concentrations (mgm-3) using ART

Moisture content <5% moisture 5-10% moisture

Powder weight fraction

Substantial Main component

Substantial Main component

Coarse dust 0.46(0.25-0.8)

1.1(0.59-2)

0.046(0.025-0.084)

0.11(0.059-0.2)

Granules 0.14(0.076-0.25)

0.32(0.18-0.58)

0.014(0.0075-0.025)

0.032(0.018-0.059)

Measured indoor concentrations and estimated outdoor concentrations

Estate type of asbestos in soils

% of asbestos in soils

Asbestos in building fabric

Asbestos in surface dust indoors

average asbestos in indoor air (f/ml)

estimated exposure (fml-1.hours)indoors outdoors

1970s* amosite, loose insulation

0.03-0.17 AIB/ asbestos cement

Y <0.0001 <1 20

1980s various ≤0.04 None N <0.0000009 <0.008 0.41

*The back garden at one property, where small children lived, was bare earth.

Even in a near worst case situation where ACMs were present in the house and where loose insulation was in uncovered garden soil, indoor asbestos concentrations were very low.

one hour/day for 15 years of childhood. Fibre concentrations were estimated on the basis of IOM data (below-left) and also data published by RIVM. Cancer risks calculated using the relationship published by Hodgson and Darnton (2000).