Toxicity carbaryl

Johnston, G.O, Walker, C.H., and Dawson, A. (1994). Potentiation of carbaryl toxicity to the hybrid red-legged partridge following exposure to malathion. Pesticide Biochemistry and Physiology 49, 198-208. 

Lieske CN, Clark JH, Maxwell DM, et al Studies of the amplification of carbaryl toxicity by various oximes. Toxicol Lett 62 127-137, 1992... 

Ixe, R.M. (1972). Xenobiotic detoxication potential and drug induced changes in carbaryl toxicity in the alfalfa leafcutter bee. Megachile rotundata (Eabri-cius). Diss. Abst.y Int. serie B. 33, no. 1. 

Lee, R.M. and Brindley, W.A. (1974). Synergist ratios, EPN detoxication, lipid and drug-induced changes in carbaryl toxicity in Megachile pacifica. Environ. Entomol. 3, 899-907. 

Environmental. The A/-methylcarbamates generally are biodegradable and of low soil persistence with half-Hves for carbaryl and aldicarb of 1—2 weeks and of carbofuran of 1—4 months. Certain carbamates are highly toxic to birds with oral LD qS for mallard, eg, pheasant, in mg/kg carbofuran, 0.40, 4.2 mexacarbate, 3.0, 4.5 and methomyl, 16, 15 compared to carbaryl >2000. Fish toxicity of carbamates is generally low, but these compounds are extremely toxic to bees. In cases of human poisoning, atropine is a specific antidote. 

Naphthol is mainly used in the manufacture of the insecticide carbaryl (59), l-naphthyl A/-methyicarbamate/ iJ-2j5 - (Sevin) (22), which is produced by the reaction of 1-naphthol with methyl isocyanate. Methyl isocyanate is usually prepared by treating methylamine with phosgene. Methyl isocyanate is a very toxic Hquid, boiling at 38°C, and should not be stored for long periods of time (Bhopal accident, India). India has developed a process for the preparation of aryl esters of A/-alkyl carbamic acids. Thus l-naphthyl methylcarbamate is prepared by refluxing 1-naphthol with ethyl methylcarbamate and POCl in toluene (60). In 1992, carbaryl production totaled > 11.4 x 10 t(35). Rhc ne-Poulenc, at its Institute, W. Va., facihty is the only carbaryl producer in United States. 

The insecticide carbaryl can be produced by several routes, some of which do not use methyl isocyanate, or which generate only small quantities of this toxic material as an in-process intermediate (Kletz, 1991b). One company has developed a proprietary process for manufacture of carbamate insecticides which generates methyl isocyanate as an in-situ intermediate. Total methyl isocyanate inventory in the process is no more than 10 kilograms (Kharbanda and Stallworthy, 1988 Manzer, 1994). 

The widely used insecticide carbaryl (FD50=270 mg/kg) transforms in oxidizing processes into 5-oxynaphthyl-N-methylcarbamate, a substance that is as toxic as carbaryl itself (FD50=297 mg/kg) [30, 33]. One of the metabolites of the fungicide benomyl, the methyl ester carbamino acid (BMK, carbendazim), is also toxic to fungi [33]. 

McKim, J.M., P.K. Schmeider, G.J. Niemi, R.W. Carlson, and T.R. Henry. 1987. Use of respiratory-cardiovascular responses of rainbow trout (Salmo gairdneri) in identifying acute toxicity syndromes in fish. Part 2. Malathion, carbaryl, acrolein and benzaldehyde. Environ. Toxicol. Chem. 6 313-328. 

Although previous applications of this technique in our laboratory had been concerned with aquatic animal metabolism of pesticides such as DDT, parathion, carbaryl, and trifluralin (14, 15), we also became interested in comparing metabolic routesljy means of a "metabolic probe". Such a compound ideally should be stable to nonbiological degradation, of low toxicity to maximize the dose, and subject to as many major routes of metabolism as possible without undue analytical complexity. 

Carbaryl is perhaps one of the best studied of the major lawn chemicals, and evidence of health-related risks related to its use date as early as the late 1960s, when studies of the chemical revealed both its toxicity and its potential impact on animal (and potentially human) reproduction. In 1969 the U.S. Department of Health Education and Welfare recommended restrictions on the use of the chemical, owing to mounting evidence that it may be tetragenic (causing birth defects). Later research in the 1980s pointed towards the possible implication of carbaryl in neurotoxicity, brain function, and aggressive behavior. ... 

Arunachalam, S Jeyalakshmi, K., and Aboobucker, S. Toxic and sublethal effects of carbaryl on a freshwater catfish, Mystus vittatus (Bloch), Arch. Environ. Contam. Toxicol, 9(3) 307-316, 1980. 

Edmiston, C.E., Jr., Goheen, M., Malaney, G.W., and Mills, W.E. Evaluation of carbamate toxicity acute toxicity in a culture of Paramecium multlmlcronucleatum upon exposure to aldicarb, carbaryl, and mexacarbate as measured by a Warburg respirometry and acute plate assay. Environ. Res., 36(2) 338-350, 1985. 

Carbamates act similar to organophosphates by interfering with nerve system enzymes. They are derived from carbamic acid, H NCOOH, and share many of the properties of organophosphates (Figure 18.9). The carbamate known as carbaryl (commercial trade name is Sevin) was synthesized in 1956 and has been used extensively since that time. Carbaryl s advantages are that its toxicity to mammals is low and it kills a broad spectrum of insects. It is widely used in a number of household lawn and garden products. Other common carbamates include aldicarb (Temik) and carbofuran (Furadan). 

Uncharged carbamates, such as carbaryl (8.20, sevin), can penetrate the CNS of insects (which do not use AChE in their neuromuscular junction) and they act quite selectively as insecticides with a low toxicity to mammals (median lethal dose [LDjg] in the rat = 540 mg/kg, p.o.). Many useful insecticides can thus be found in this group. Malathion (8.21) is a pro-drug, since the thiophosphate must be bioactivated to the phosphate form—a transformation carried out by insects but not mammals. Additionally, the ester groups of malathion are rapidly hydrolyzed in higher organisms to water-soluble and... 

Carbamates are also used as insecticides and again, their trade names are probably familiar if you have done any serious gardening and pest control. The use of these compounds is restricted to certain parts of the growing cycle and specific non-food produce. Notice their low degree of dermal toxicity. Carbaryl, for example, is used topcially in some countries to get rid of head lice. It was the misuse of Temik several years ago on watermelons in California which... 

Dispositional interactions are those in which one chemical affects the disposition of the other, usually metabolism. Thus, one chemical may increase or inhibit the metabolism of another to change its toxicity. For example, 2,3-methylenedioxynaphthalene inhibits cytochrome P-450 and so markedly increases the toxicity of the insecticide carbaryl to flies (potentiation) (see chap. 5). Another example, which results in synergy, is the increased toxicity of the organophosphorus insecticide malathion (see chap. 5) when in combination with another organophosphorus insecticide, EPN. EPN blocks the detoxication of malathion. Many chemicals are either enzyme inhibitors or inducers and so can increase or decrease the toxicity of other chemicals either by synergism or potentiation (see chap. 5). 

Pesticides are also a major source of concern as water and soil pollutants. Because of their stability and persistence, the most hazardous pesticides are the organochlorine compounds such as DDT, aldrin, dieldrin, and chlordane. Persistent pesticides can accumulate in food chains for example, shrimp and fish can concentrate some pesticides as much as 1000- to 10,000-fold. This bioaccumulation has been well documented with the pesticide DDT, which is now banned in many parts of the world. In contrast to the persistent insecticides, the organophosphorus (OP) pesticides, such as malathion, and the carbamates, such as carbaryl, are short-lived and generally persist for only a few weeks to a few months. Thus these compounds do not usually present as serious a problem as the earlier insecticides. Herbicides, because of the large quantity used, are also of concern as potential toxic pollutants. Pesticides are discussed in more detail in Chapter 5. 

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