| 毒性の概要 | Food represents the major source of carbaryl intake for the general population. ... The general population can be exposed to carbaryl during pest control operations in both the home & recreation areas. Workers can be exposed to carbaryl during its manufacture, formulation, packing, transportation, storage, & during & after application. ... Significant dermal exposure may occur in industrial & agricultural workers if protective measures are inadequate. Carbaryl is rapidly absorbed in the lungs & digestive tract. ... The principal metabolic pathways of carbaryl are ring hydroxylation & hydrolysis. As a result, numerous metabolites are formed & subjected to conjugation with the formation of water-soluble sulfates, glucuronides, & mercapturates, excreted in the urine. Hydrolysis results in the formation of 1-naphthol, carbon dioxide & methylamine. Hydroxylation produces 4-hydroxycarbaryl, 5-hydroxycarbaryl, N-hydroxymethylcarbaryl, 5-6-dihydro-5-6-dihydroxycarbaryl & 1,4-naphthalendiol. The principal metabolite in humans is 1-naphthol. Under normal exposure conditions, the accumulation of carbaryl in animals is unlikely. Carbaryl is excreted primarily via the urine, since the product of its hydrolysis, 1-naphthol, is mainly detoxified to water-soluble conjugates. Enterohepatic cycling of carbaryl metabolites is also considerable, especially after oral administration. ... Carbaryl metabolites are also present in a small percentage of the absorbed doses in saliva & milk. ... The acute toxicity for birds is low. ... Carbaryl is very toxic for honey-bees & earthworms. ... The acute toxicity ... varies considerably according to species, formulation & vehicle. ... Carbaryl is a mild eye irritant & has little or no sensitizing potential. ... Carbaryl has a low cumulative potential. Carbaryl has been shown to affect mammalian reproduction & perinatal development adversely in a number of species. Effects on reproduction include impairment of fertility, decreased litter size, & reduced postnatal viability. Developmental toxicity is seen as increased in utero death, reduced fetal weight, & the occurrence of malformation. With the exception of a small number of studies, all adverse reproductive & developmental effects were noted only at doses that caused overt maternal toxicity, &, in a number of cases, the maternal animal was more sensitive to carbaryl than the conceptus. The maternal toxic effects included lethality, decreased growth, & dystocia. ...The available evidence indicates that carbaryl does not have any DNA-damaging properties. ... Negative results were obtained in tests for gene mutations in a large number of bacterial assays ... The available database does not support the presumption that carbaryl poses a risk of inducing genetic changes in ... humans. Carbaryl has been studied for its carcinogenic potential in numerous studies on rats & mice. The results of most of these studies were negative ... The effects of carbaryl on the nervous system are primarily related to cholinesterase inhibition & are usually transitory. ... Carbaryl has been reported to affect coagulation ... Carbaryl binds free blood amino acids. Disturbances have been reported in the carbohydrate metabolism & protein synthesis & detoxification function of the liver in mammals. Carbaryl is a weak inducer of hepatic microsomal drug-metabolizing activity. ... Carbaryl has been reported to incr the gonadotropic function of the hypophysis of rats. Carbaryl is an inhibitor of cholinesterase activity. This effect is dose-related & quickly reversible. ... All identified metabolites of carbaryl are appreciably less active cholinesterase inhibitors than carbaryl itself. Carbaryl is easily absorbed /in humans/ through inhalation & via the oral route & less readily by the dermal route. Since the inhibition of cholinesterase is the principal mechanism of carbaryl action, the clinical picture of intoxication is dominated by ... symptoms, such as: increased bronchial secretion, excessive sweating, salivation, & lacrimationpinpoint pupils, bronchoconstriction, abdominal cramps (vomiting & diarrhea)bradycardiafasciculation of fine muscles (in severe cases, diaphragm & respiratory muscles also involved)tachycardiaheadache, dizziness, anxiety, mental confusion, convulsions, & coma& depression of the respiratory center. Signs of intoxication develop quickly after absorption & disappear rapidly after exposure ends.... In cases of occupational overexposure to carbaryl, mild symptoms are observed long before a dangerous dose is absorbed, which is why severe cases of occupational intoxication with carbaryl are rare. During agricultural application, dermal exposure may play an important role. ... The appearance of a skin rash after accidental splashing with carbaryl formulations has been described. ... The most sensitive biological indicator of carbaryl exposure is the appearance of 1-naphthol in the urine & the decr of cholinesterase activity in the blood. ... The hazards of carbaryl for human beings are judged to be low, because of its low vapor pressure, rapid degradation , rapid spontaneous recovery of inhibited cholinesterase, & the fact that symptoms usually appear well before a dangerous dose has accumulated in the body. ...Carbaril is a cholinesterase or acetylcholinesterase (AChE) inhibitor. Carbamates form unstable complexes with chlolinesterases by carbamoylation of the active sites of the enzymes. This inhibition is reversible. A cholinesterase inhibitor suppresses the action of acetylcholine esterase. Because of its essential function, chemicals that interfere with the action of acetylcholine esterase are potent neurotoxins, causing excessive salivation and eye-watering in low doses. Headache, salivation, nausea, vomiting, abdominal pain and diarrhea are often prominent at higher levels of exposure. Acetylcholine esterase breaks down the neurotransmitter acetylcholine, which is released at nerve and muscle junctions, in order to allow the muscle or organ to relax. The result of acetylcholine esterase inhibition is that acetylcholine builds up and continues to act so that any nerve impulses are continually transmitted and muscle contractions do not stop. |
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