Mutagen Formation Potential of Composite Samples Prepared by Biodegradation of Agricultural Chemicals

Abstract

Ten mg-AC/L aqueous solutions of 18 kinds of agricultural chemicals (ACs), such as organophosphorus, organochlorine and amidic chemicals, were prepared and underwent the biodegradation test. The samples attained through the test were considered to contain various decomposition products, hereafter referred to as composite samples. Mutagenicity and mutagen formation potential (MFP) were measured for the composite samples, and the test results revealed that the ACs tested in the present study do not produce mutagens as a result of undergoing the biodegradation test. However, 12 out of 18 samples manifested statistically significant MFP. All of the 12 ACs, except for iminoctadine-triacetate, were aromatic compounds. Specific activities for thiram and DDVP, which were reported to be mutagenic, were measured, showing 320 net rev./mg and 190 net rev./mg respectively. Compared with these values, MFP of the composite samples attained from ferimzone, pyridiphenthion, bentazone, bensultap, and napropamide were greater. Accordingly, it was suggested that some ACs, though they were non-mutagenic compounds, could form strong mutagens when they were biodegraded in a water environment, and the decomposition products subsequently intruded into the raw water for water supply, and the water was then chlorinated at a purification plant.