Biochemical effects in mice following exposure to wheat treated with chlorfenvinphos and carbophenothion under laboratory and field conditions

The wood mouse (Apodemus sylvaticus) has been used as an indicator species to assess, both in the field and the laboratory, the effects of carbophenothion and, in the laboratory, the effects of chlorfenvinphos as seed dressings on winter wheat. Wood mice were fed in the laboratory with wheat treated with carbophenothion and chlorfenvinphos and the effects on esterase levels were determined for periods of up to 7 days and on returning the mice to untreated wheat. The significant inhibition of plasma acetylcholinesterase and cholinesterase and brain and liver nitrophenyl acetate esterase during the 6-month period after carbophenothion-treated grain was drilled was found to reflect the carbophenothion residue in the gut contents of the mice. The degree of esterase inhibition differentiated mice trapped on the field from those caught in adjacent woodland. Inhibition of the plasma, brain, and liver esterases in wood mice fed wheat treated with the recommended rate of carbophenothion confirmed that the continued esterase inhibition obtained in the field-trapped mice during the field trial was due to chronic pesticide exposure. The pattern of esterase inhibition in the wood mice reflected the persistence of the two organophosphorus pesticides.