1,721,360 research outputs found
Indoor spraying with the pyrethroid insecticide lambda-cyhalothrin: effects on spraymen and inhabitants of sprayed houses
No full textIn March 1990 a study was carried out in the village of Kicheba, United Republic of Tanzania, in which the pyrethroid insecticide lambda-cyhalothrin was sprayed on all the internal surfaces of houses and other shelters at a coverage of about 25 mg of active ingredient per m2. Every day for 6 days, 12 spraymen and 3 squad-leaders were interviewed about symptoms of overexposure to the insecticide. Each sprayman used up to 62 g of lambda-cyhalothrin over 2.7-5.1 hours every day. All the spraymen complained at least once of symptoms that were related to exposure to lambda-cyhalothrin, the commonest being itching and burning of the face, and nose or throat irritation frequently accompanied by sneezing or coughing. Facial symptoms occurred on non-protected areas only. The symptoms were experienced at various times after the beginning of exposure and disappeared before the following morning. The number of subjects affected and the duration of their facial symptoms were proportional to the amount of compound sprayed. A sample of individuals was interviewed 1 day and 5-6 days after their houses had been sprayed. One woman, who entered her house 30 minutes after the end of spraying, complained of periorbicular itching, but this lasted only a few minutes. No other significant, insecticide-related adverse effect was reported by the inhabitants of the sprayed houses
Exposure to multiple chemicals : when and how to assess the risk from pesticide residues in food
No full textExposure to multiple pesticide residues derived from food is a common occurrence in the general population. Levels of exposure are usually low, below the effective doses. Interactions, such as potentiation and synergism, are not expected to occur at these doses. Available evidence indicates that risk assessment should be carried out for mixtures containing compounds with the same mode of action, since their effects are expected to cumulate. Several methods are available to assess this cumulative risk that differs in the mathematical expression of the data, in the level of uncertainty and transparency, in the requirement of efforts and resources
Experimental and clinical toxicology of anticholinesterase agents
No full textSeveral organophosphorus compounds (OP) and carbamates (CA) are used as insecticides or warfare agents (OPs only). Their acute toxic effect in the central and peripheral nervous system is due to inhibition of acetylcholinesterase (AChE) at nerve endings which causes accumulation of acetylcholine and consequently overstimulation of the nicotinic and muscarinic receptors. The cholinergic syndrome appears at approximately 50% AChe inhibition whereas death is believed to occur at > 90%. Inhibition of AChE (phosphorylation) by most OPs is irreversible whereas CAs reversibly inhibit AChE (spontaneous reactivation with a t(1/2) of minutes); dimethylphosphorylated AChE partially and slowly (t(1/2) = 1-2 h) reactivates. Although long-term, mild neurobehavioural changes of questionable significance have been reported in some instances, recovery from the cholinergic syndrome appears to be complete, unless lesions develop in the central nervous system as a consequence of either convulsions or anoxia. Certain OPs and CAs have been reported to interact with cholinergic receptors in vitro. The toxicological relevance of these interactions is still not clear. Certain OPs cause OP-induced delayed polyneuropathy (OPIDP) which develops 2-5 weeks after an acute poisoning. The molecular target is believed to be neuropathy target esterase (NTE). OP insecticides are more potent AChE inhibitors rather than NTE inhibitors and therefore, the dose required to cause OPIDP is much higher than that causing the cholinergic syndrome. In the experimental animal, OPIDP is associated with > 70% NTE inhibition after single or repeated exposures. The threshold in man is not known, although there are indications that it is similar. Some non-neuropathic esterase inhibitors (OPs, CAs, sulfonyl fluorides) exacerbate the clinical outcome of OPIDP and other chemical axonopathies, and of nerve crush. The phenomenon has been called promotion and has so far been observed in experimental animals only
Influence of dithiocarbamates on the development of organophosphate induced delayed polyneuropathy (OPIDP)
No full textIn: The Toxicologist, 48 1-
Matematica e dialettica. Rosmini e una possibile fonte della Logica hegeliana
No full textAnalisi della tesi rosminiana, secondo cui l'opera "De nihilo geometrico" sarebbe una delle fonti della dottrina hegeliana sul calcolo infinitesimal
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