Summary and selection of suitable assays

Use a rapid, easy to interpret and preferably sensitive biological system to provide initial quantitative spatial data concerning the likelihood of exposure. When possible, use should allow risk visualisation via geographical information systems. By overlaying this information onto chemical analysis data, contamination hot spots can be identified. 

Apply biological methods capable of accurate assessment of ecological effects that integrate mixture and bioavailability effects. 

The diverse nature of soil contamination means that it is currently not possible to recommend a single assay for soil quality assessments in all circumstances. A suite of assays is likely to be the most useful approach. Within the suite, complementary methods applicable for a range of contaminants at different concentration levels and in a range of soils are needed. These include bioassay/biomarker/ biosensor methods that  

In recommending assays, the existence of an internationally standardised protocol is an important factor for the credibility of a given test. Coupled to this, however, is the recognition that there can be a considerable time delay before standardisation is attained and in any case current standard tests have not been fully developed for contaminated soil assessment. Even when tests become standardised, developments do not cease and methods can change on the basis of improved knowledge. For example, a revision of the OECD terrestrial plant growth test (OECD, 2000) first published in 1984 (OECD, 1984) has been 

Accepting that the absence of an international guideline should not be a barrier to the use of developing methods, further useful methods can be identified. Some, such as the bait lamina (Tome, 1990a) and earthworm lysosomal membrane stability assay (Weeks and Svendsen, 1996), are now well established in the scientific literature and appear particularly suited to assessing exposure and effects. Some of the biomarker techniques, such as ChE inhibition, metallothio-nein induction and possibly immune function assessment, can be used to provide valuable information regarding the nature of the chemicals present and the exposure of soil species. 

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