Organic pollutants are widespread in urban soils, originating from activities of the petroleum industry, pesticides, old gasworks and numerous other sources. For that reason, the ingestion of polluted soil by children when playing outdoors is a key consideration for industry when undertaking risk assessments of contaminated land.
A 2010 government consultation estimated that perhaps 20–30 per cent of the removal of pollutants from contaminated land under the current planning system may be ’unnecessary’. Excessive clean-up work could be costing the construction industry an extra £140m–£210m per annum and potentially excluding some sites for redevelopment completely.
One reason for that is that current methods for assessing the risk posed by contaminated land to human health may overestimate the amount of pollutant that can be absorbed by the gut safely. This is because such tests measure the total soil concentration of a pollutant rather than the amount of chemical that is released during digestion.
Chemical tests such as the physiologically based extraction test (PBET), do imitate the conditions of the human gastro-intestinal tract to provide a more accurate indication of how such chemicals might be released into the body. However, even though passage through the colon accounts for approximately 80 per cent of the transit time through the human digestive tract, these PBET tests only chemically model the stomach and small intestine compartments.
Dr Chris Collins from Reading’s Department of Geography and Environmental Science has developed a new test — the colon-extended PBET (CE-PBET) test — that does just that, more accurately replicating the body’s processes when it ingests polluted soil. This, it is claimed, will give companies vastly improved data compared to current models, allowing them to make more informed decisions when remediating sites.
Dr Chris Collins said: ’Our recently developed test allows more representative measurements to be undertaken of the pollutants released during digestion. The test will also help local government determine if there is genuine risk from sites that may have low levels of residual pollution, such as allotments.’
Currently, the new test is being used by three industrial customers and a local council.
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