The opportunity presented by the introduction of a coal-based granular formulation of the carbamate nematocide, aldicarb for use on sugar beet and potatoes in the United Kingdom has been used to evaluate a number of new methods for the assessment of the environmental hazard presented by pesticides. In an intensive field trial with sugar beet, well established biological procedures for recording changes in animal populations and behaviour were combined with a planned programme involving the sampling of animals, plants and soil. Emphasis was placed on sampling and observing mammals in addition to birds which have been more extensively studied in the past. The samples were submitted to a variety of chemical and biochemical analyses designed to reveal the extent to which the pesticide was distributed temporally and spatially and the effects it produced on individuals. The results indicate that although the pesticide is not persistent, it is mobile especially in wet soil, systemic in plants and can be found widely in the local vertebrate fauna for up to 90 days after application. Specific hazards were identified as arising from the ingestion of uncovered granules and from worms containing residues coming to the surface following application in wet conditions.