Fenitrothion toxicity

Sultatos LG, Huang GJ, Jackson O, et al. 1991. The effect of glutathione monoethyl ester on the potentiation of the acute toxicity of methyl parathion, methyl paraoxon or fenitrothion by diethyl maleate in the mouse. Toxicol Lett 55 77-83. 

According to the results obtained, and assuming that the simple additive approach applied is valid, malathion appears to be the main contributor to Daphnia toxicity (98% toxic contribution on average for all samples) molinate, fenitrothion, and malathion would be the most relevant pesticides in the case of V. fischeri... 

In all cases, the concentrations of malathion and fenitrothion measured in water (up to 5.8 and 1.2 pg/L, respectively) were below the LC50 (lethal concentration 50%) values reported for these compounds in oysters and mussels, which range between 2.7 and 278 mg/L in the case of malathion, and between 10.3 pg/L and 123 mg/L in the case of fenitrothion (http //www.pesticideinfo.org). However, it has to be stressed that these LC50 values express acute toxicity, that both malathion and fenitrothion might be bioaccumulated by molluscs (as their detection in biota suggests), and that aquatic organisms are exposed to a variety of contaminants, some of which could show synergetic or additive effects [40]. Further matters of... 

Ferrando, M.D., Sancho, E., and Andreu-Moliner, E. Chronic toxicity of fenitrothion to an alage (Nannochlorls oculata), a rotifer (Brachionus calyclflorud), and the cladoceran (Daphnia magna), Ecotoxicol. Environ. Saf, 35(2) 112-122, 1996. 

Johnston, JJ. and Corbett, M.D. The effects of temperature, salinity and a simulated tidal cycle on the toxicity of fenitrothion to Callinectessapidus. Comp. Biochem. Physiol. C, 80(1) 145-149, 1985. 

In order to evaluate the potential hazards chemical insecticides pose to forest environments, it is essential that adequate and reliable research data be generated on their environmental chemistry (distribution, persistence, movement, metabolic degradation, toxicity, fate, etc.). This paper gives a brief account of some laboratory and field research activities carried out at the Forest Pest Management Institute, Canadian Forestry Service to meet this requirement. Using two chemical insecticides which are extensively used now in forest insect control programs in Canada Viz aminocarb [Trade name, Matacil 4-dimethylamino-m-tolyl N-methylcarbamate] and fenitrothion [0,0-dimethyl 0-(3-methyl-4-nitrophenyl) phosphorothioate], studies conducted at the Institute to elucidate the environmental behavior and fate of forestry insecticides in general will be discussed. 

FIGURE 7.4 Species sensitivity distribution for tropical or temperate arthropods exposed to fenitrothion in acute toxicity tests. Source Redrawn from data of Maltby et al. (2005). 

Introducing a methyl group into the ring, as in fenitrothion, increases the hydrophobicity and increases the affinity to the active site of the enzyme, but reduces its reaction velocity. The net result on AChE is therefore much the same. However, the changes make it less toxic to mammals, while the... 

Table 5.3 Toxicity of Fenitrothion, Parathion, and Fenthion according to G. Schrader (1963)...

Note This table illustrates the high toxicity of parathion compared with two similar analogues. The insecticidal properties of fenitrothion are approximately similar to those of parathion. 

Technical fenitrothion always contains the S-methyl isomer in varying quantities. The toxicity of the thiol isomer is higher and its stability to hydrolysis... 

The oral of fenitrothion for rats is 500 mg/kg. The methyl group in the m-position reduces its toxicity thirty-fold compared to that of parathion-methyl... 

A sizable proportion of the stocks listed in the table below contain persistent organochlorines, such as DDT, dieldrin and lindane, which are banned in many countries (Table 10). Obsolete stocks also contain acutely toxic organophosphates such as fenitrothion and malathion, as well as many chemicals with no identification whatsoever. 

Microbial reduction of toxic organics is carried out by reduction enzymes. Major reduction reactions of selected toxic organics are shown in Table 13.5. The reduction of the nitro group to amine involves the formation of a nitro and a hydroxyamino group. This type of reduction reaction occurs during the microbial metabolism of various pesticides. Organophosphorous pesticides such as para-thion, paraoxon, or fenitrothion are often reduced to nontoxic amino compounds (Miyamoto et al., 1966 Matsumura and Benezet, 1978). 

Fenitrothion (Sumithion) was developed by Sumitomo as a potent phosphorus insecticide with low toxicity. Sumitomo developed the industrial synthesis of aiiethrin in the early 1950 s, and continued to invent effective pyrethroids such as fenvalerate and metofiuthrin. Mitsufs etofenprox is a unique pyrefhroid possessing no stereogenic carbon atom. The discovery of photo-stable synthetic pyrethroids such as fenvalerate and etofenprox enabled their widespread use in outdoor agriculture. 

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