Troubling and troublesome worlds of urban soil trace element contamination baselines/

Many urban areas feature soil pollution legacies that are augmented by recurring contaminant emissions. Because trace elements (like arsenic or lead) are not degradable like organic pollutants, trace element contamination is a lasting environmental threat to human health. Conventionally, the problem is assessed by comparisons with soil quality standards based on background soil concentration levels, which constitute a variety of baseline values. However, baselines are fraught with technical challenges and politically problematic assumptions. These are illustrated by soil quality standards (ambient and maximum allowable levels) addressing soil trace element contamination. These baselines used to assess toxicological threats (beyond soils) are not only contingent on ecological complexities and shifts, but also on national and institutional setting, testifying to their social, not just technical basis. As shown through two US examples, the latter social dimensions do not merely reflect differences in levels of risk acceptability. Soil quality standards can be used to pre-empt public debate over, among other matters, land use decisions. There are therefore both technical and political reasons to question such baselines, which end up becoming attempts to conceal uncertainties and partial or incomplete understandings. An ecosocialist Critical Physical Geography approach is explored that takes ecological and social contexts and their dynamism as primary means to assess trace element contamination.