This International Standard specifies a rapid method for assessing solid samples in an aerobic suspension, by determining the inhibition of dehydrogenase activity of Arthrobacter globiformis using the redox dye resazurin. It is applicable for assessing the effect of water-soluble and solid matter bounded non-volatile contaminants of natural samples, such as soils and waste materials. Although not the main purpose, the contact test can additionally be used for testing the effect of chemicals, as described in the Annex C. The test yields a result within 6 h and can therefore be used for screening potentially contaminated material.