Acute toxicities resistance

The rapid growth in the use of OPs and the proliferation of new active ingredients and formulations was not without its problems. Some OPs proved to be too hazardous to operators because of very high acute toxicity. A few were found to cause delayed neurotoxicity, a condition not caused by ChE inhibition (e.g., mipafox, lepto-phos). There was also the problem of the development of resistance, for example, by... 

See a/so Methacrylic ester monomers Methacrylic ester polymers Methacrylic monomers acute toxicity of, 16 260t exposure to, 16 261 for 193-nm resists, 15 178-179 physical properties of, 16 227-235t, 278t polymerization of, 14 259 Methacrylates... 

For highly potent APIs, profound effects can occur at low ng levels, the adverse effect of ethynylestradiol on fish populations is one example [107]. Another example is the development of resistant bacterial strains induced by the release of antibiotics into the environment [112, 113]. Dome et al. [114] concluded that fluoxetine, ibuprofen, diclofenac, propranolol and metoprolol exhibit relatively high acute toxicity to aquatic species. In addition, due to the inherent properties of these chemicals, pharmacodynamic effects were observed in the heart rate of Daphnia magna for the (3-blockers propranolol and metoprolol. 

Mammalian PLANT RESISTANCE TO INSECTS Table I acute toxicities of plant terpenes ... 

Table 9-5 presents data from various animal studies on the acute toxicity of sulfur dioxide. These studies support findings from the human studies, indicating that sulfur dioxide exerts its effect primarily on the respiratory system. Acute effects at relatively low concentrations (<20ppm) induced transient bronchoconstriction and increases in airway resistance. Higher concentrations produced more sustained biochemical, clinical, and histologic changes in the respiratory system. No material effects were noted in organs outside of the respiratory tract after acute exposure to sulfur dioxide. 

Polychlorinated diphenyl ethers (PCDE) are common impurities in chlorophenol formulations, which were earlier used as fungicides, slimicides, and as wood preservatives. PCDEs are structurally and by physical properties similar to polychlorinated biphenyls (PCB). They have low water solubility and are lipophilic. PCDEs are quite resistant to degradation and are persistent in the environment. In the aquatic environment, PCDEs bioaccumulate. These compounds are found in sediment, mussel, fish, bird, and seal. PCDEs show biomagnification potential, since levels of PCDEs increase in species at higher trophic levels. PCDEs are also detected in human tissue. Despite the persistence and bio accumulation, the significance of PCDEs as environmental contaminants is uncertain. The acute toxicity and Ah-receptor-me-diated (aryl hydrocarbon) activity of PCDEs is low compared to those of polychlorinated di-benzo-p-dioxins (PCDD) and dibenzofurans (PCDF). Due to structural similarity to thyroid hormone, PCDEs could bind to thyroid hormone receptor and alter thyroid function. Furthermore, PCDEs might be metabolized to toxic metabolites. In the environment, it is possible that photolysis converts PCDEs to toxic PCDDs and PCDFs. 

A large body of evidence is available examining the acute toxicity of acetaminophen in animal models. Mice and rats have been widely used to study the toxic effects of acetaminophen. Since the rat is relatively resistant, the mouse has been the most widely used species to study both the mechanisms of acetaminophen toxicity and to examine chemicals that potentiate or protect from the toxicity. Hepatotoxic-ity and nephrotoxicity are the two main effects associated with acute overdose of acetaminophen. Of these, death in most species is due to acute hepatic failure. LD50 values range from 350 to 4500mgkg depending on the species and the route of acetaminophen administration, mice (LD50 350-... 

Hydrocarbon compounds such as fuels, lubricating oils and creosote contain toxic components. Naphthalene and its methyl-substituted derivatives are some of the most acutely toxic, water-soluble components of crude oils. As the molecular size of hydrocarbons increases, their lipophilicty, environmental persistence and mutagenicity also increase. Many chemicals represent classes of molecules not previously investigated, some have no close structural analogs in nature, and there are those that were intentionally developed to be resistant to microbial attack and to persist in nature. 

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