Factors pesticide toxicity

Luttik R, Aldenberg T. 1997. Extrapolation factors for small samples of pesticide toxicity data Special focus on LD50 values for birds and mammals. Environ Toxicol Chem 16 1785-1788. 

Other examples are carcinogenicity studies on complex mixtures (petroleum middle distillates, foundry fumes, pesticides, heterocyclic amines, diesel exhaust, and solid particles) neurotoxicity studies of mixtures of solvents alone or in combination with exposure to physical factors and toxicity stndies of outdoor air pollutants, focusing... 

The reason for conducting the study, which is often related to the potential end use of the anti-ChE (e.g., for pesticides, a determination of all potential occupational hazards, factors influencing toxicity, safe working conditions, protective and precautionary measures, and therapeutic measures for chemical warfare purposes, an a.ssessment of the lethal potential of the anti-ChE and thus its threat capability and, secondary to this, considerations of protective and antidotal measures). 

Depending on the duration, frequency, and level of exposure, anti-AChE pesticides and related compounds can adversely affect one or all three components of the matemal-placental-fetal unit, The outcome of placental toxicity to these pesticides can be Influenced by three major factors maternal toxicity, placental tran.sfer, and placentai-fetal metabolism. Evidence suggests that the pesticide residue is present not only in the exposed mother... 

Hazard identification, step one, means identification of new chemicals or other factors that may cause harmful health effects. Previously, novel hazards were usually observed in case studies or after accidents or other excessive exposures, usually in occupational environments. Today, thorough toxicity studies are required on all pesticides, food additives, and drugs. New chemicals also have to be studied for their potential toxic effects. Thus, earlier hazards were in most cases identified after they had caused harmful effects in humans. Today, most chemical products have been evaluated for their toxicity with experimental animals. Therefore, hazard identification has become a preventive procedure based on safety studies conducted before a chemical compound or product reaches the market, and before individuals are exposed to it. ... 

Mechanism of action can be an important factor determining selectivity. In the extreme case, one group of organisms has a site of action that is not present in another group. Thus, most of the insecticides that are neurotoxic have very little phytotoxicity indeed, some of them (e.g., the OPs dimethoate, disyston, and demeton-5 -methyl) are good systemic insecticides. Most herbicides that act upon photosynthesis (e.g., triaz-ines and substituted ureas) have very low toxicity to animals (Table 2.7). The resistance of certain strains of insects to insecticides is due to their possessing a mutant form of the site of action, which is insensitive to the pesticide. Examples include certain strains of housefly with knockdown resistance (mutant form of Na+ channel that is insensitive to DDT and pyrethroids) and strains of several species of insects that are resistant to OPs because they have mutant forms of acetylcholinesterase. These... 

It is known that pesticide aerosols, formed when the pesticide steam settles on surfaces of miniscule droplets of water, are much more toxic than the steam form of the same pesticide. This circumstance turned out to be extremely important. Table 2.2 gives an idea of how dangerous pesticides are to humans when we ignore the role of factors such as atmospheric humidity. Data from... 

Due to the low volatility of cyromazine and the use of water-soluble bags for packaging the Trigard formulation, the main routes of exposure were expected to be from direct contact with the product or spray mixture on contaminated surfaces. Previous experience with pesticides worker exposure studies indicated that exposure from vapors or spray mist would be a minor factor. This can easily be confirmed by the PHED or similar published sources however, the extent of exposure from inhaling the product as dust is less well known. This route of exposure was also assumed to be minor, particularly with the use of water-soluble bag packaging. Given the low mammalian toxicity of cyromazine, the operators did not wear respiratory protection. 

Eisler, R. 1969. Acute toxicities of insecticides to marine decapod crustaceans. Crustaceana 16 302-310. Eisler, R. 1970a. Latent effects of insecticide intoxication to marine molluscs. Hydrobiologia 36 345-352. Eisler, R. 1970b. Factors Affecting Pesticide-Induced Toxicity in an Estuarine Fish. U.S. Bur. Sport Fish. Wildl., Tech. Paper 45. 20 pp. 

Brown, VK. and Muir, C.M.C. (1971). Some factors affecting the acute toxicity of pesticides to mammals when absorbed through skin and eyes. Int. Pest Control 13 16-21. 

Federal agencies such as the FDA and EPA require a battery of toxicity tests in laboratory animals to determine an additive s or a pesticide s potential for causing adverse health effects, such as cancer, birth defects, and adverse effects on the nervous system or other organs. Tests are conducted for both short-term (acute) and long-term (chronic) toxicity. For chronic effects other than cancer, laboratory animals are exposed to different doses to determine the level at which no adverse effects occur. This level is divided by an uncertainty or safety factor (usually 100) to account for the uncertainty of extrapolating from laboratory animals to humans and for individual human differences in... 

A second factor concerns the purity of the diet and water received by the animals. Careful chemical analysis is needed to ensure the absence of significant amounts of highly toxic chemicals, such as aflatoxin, metals such as lead, arsenic, or cadmium, or certain pesticides, that may be present in water and various feed ingredients. 

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