Metabolism of Organophosphorus Insecticides in Aquatic Organisms, with Special Emphasis on Fenitrothion

Abstract

The organophosphorus compounds constitute one major group of insecticides, and a certain portion thereof may be transported to the aquatic environment resulting either from the actual use on paddy fields or from unavoidable transmittance to waterways. However, possibly because of its relatively shorter persistence, the translocation and transformation of organophosphorus compounds in the aquatic environment has not been extensively investigated as compared with more persistent organοchlorine compounds.Fenitrothion, O,O-dimethyl O-(3-methyl-4-nitrophenyl) phosphorothioate, is widely used for the control of paddy field insects and forest protection in several countries, and since it is rather highly toxic to some aquatic organisms (LC 50 after 48hr exposure, 1.28 ppm for rainbow trout, 2.72 ppm for bluegill, 4.4 ppm for carp, LC 50 after 3 hr exposure, 0.0092 ppm for daphnia and no-effect dosage after 4 week exposure, 0.02 ppm for carp) (1, 2), the knowledge on degradation and metabolism of the compound in the aquatic environment is important for assessing short-term and long-term impacts on the non-target aquatic organisms.In this article metabolism and bioaccumulation of fenitro thion in several aquatic species are dealt with under laboratory conditions. Metabolism in vitroTo acquire information on the intrinsic metabolic activity of aquatic organisms, liver of carp (Cyprinus carpio Linnaeus), rainbow trout (Salmo gairdneri) and freshwater snail (Cipangopaludina japonica Martens) was dissected out, homogenized in 0.1M phosphate buffer, pH 7.5, and centrifuged at 105,000 g for 60 min to obtain the microsome-equivalent (described as the microsomal fraction hereafter) fraction. The protein content of microsomal and sub microsomal (supernatant fractions by Lowry's method, micro somal P-450 content (3), activity of aniline hydroxylase (4) and aminopyrine N-demethylase (_5) were determined. Table I shows the results which reveal that the drug-0-8412-0489-6/79/47-099-003$05.00/0

Linking behavioural alterations with biomarkers responses in the European seabass Dicentrarchus labrax L. exposed to the organophosphate pesticide fenitrothion

“…Fish CYP1A activity has been found to be involved in organophosphate pesticides metabolism (Flammarion et al 1998;Kitamura et al 2000;Schlenk 2005) including in fenitrothion metabolism (Miyamoto et al 1979). In the present study, EROD activity was found to be significantly increased in seabass juveniles exposed to fenitrothion at concentrations equal or higher than 1 mg l -1 (Fig.…”

Bioconcentration, Bioaccumulation, and Metabolism of Pesticides in Aquatic Organisms

“…Although closed systems equipped with volatile traps have been used to improve the recovery of 14 C, there was a failure to demonstrate the advantage of the modified system either because of insufficient volatile trapping or because of inadequate bottom sediment analyses Tsuge et al 1976). Most model ecosystem studies have utilized single applications, although Miyamoto et al (1979) examined the effect of multiple applications of fenitrothion (41) in a recirculating system; these authors reported no increase in bioaccumulation as compared with a single application. Although model systems may allow collection of valuable information on the interactions among several species, linked by a food web, obtaining time-dependent distribution data for tested pesticides and their metabolites is difficult.…”

The Toxicity of Fenitrothion and Permethrin

“…Miyamoto et al (1966) studied the degradation of fenitrothion by B. subtilis. The major metabolite was aminofenitrothion, and other minor metabolites detected were dimethyl thiophosphoric acid and desmethyl fenitrothion.…”

“…Pathway of degradation of fenitrothion by B. subtilis in environment. This figure was adopted from Miyamoto et al (1966) with slight modifications. Aminofenitrothion was the major metabolite of fenitrothion in B. subtilis.…”