Ashworth, J. and Bullecer, I. 2012. A rapid bioassay to screen soils for toxicity of residual petroleum hydrocarbons. Can. J. Soil. Sci. 92: 901-904. The following 2-h procedure is proposed as a screen to indicate how soils contaminated with petroleum hydrocarbons (PHC) might perform in bioassays required for site remediation in Canada. Bio-available PHC in soil is extracted by aqueous cyclodextrin; a centrifuged extract portion is treated with amylase, then subjected to a standard Microtox® bioassay. Extract toxicity is correlated to available PHC content.