How were the Ministry criteria determined?
The soil quality criteria for most of the chemicals of concern in the Sudbury Soils Study (such as copper, nickel, arsenic and cobalt) are based on the toxicity of these elements to plants – not humans – and are derived for soils with a pH of 5.0 to 9.0. These guidelines are based on sensitive plant species on which laboratory experiments were conducted. In some cases the test species are plants such as oats or wheat. These species may or not be relevant for Sudbury, which is why a site-specific risk assessment is being undertaken.
