In vitro and non-mammalian testing methods for determining organophosphate insecticide toxicity /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1990.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | Several toxicity testing methods were investigated in an effort to develop an alternative to the mammalian model for the acute toxicity of organophosphorous insecticides (OP). Three in vivo models and two in vitro models were tested for OP toxicity in this investigation. The chick embryo, chick, and mouse comprised the in vivo models. The in vitro systems consisted of a tissue culture model and an in vitro experiment. This study concentrated on the acute toxicity of the OP methyl parathion in non-microencapsulated and microencapsulated form. Acetylcholinesterase (AChE) inhibition was the main parameter of interest in this investigation. The mouse was the most sensitive model in acute non-microencapsulated methyl parathion intoxication with the chick and chick embryo models being less sensitive. However, when microencapsulated methyl parathion was used, the mouse was the most resistant model. Toxicity indices compare the LD₅₀'s of non-microencapsulated and microencapsulated methyl parathion. Based on these toxicity index values, the mouse model proved to be the best model when testing for the differences in toxicity between the two forms of methyl parathion. The in vitro model consisted of exposing commercially produced AChE directly with methyl parathion and testing for AChE inhibition. The in vitro model as described in this investigation was not accurate in predicting AChE inhibition from methyl parathion due to some inherent problems with the microsomal incubation and AChE assay processes. A possible AChE inhibitor, which was not methyl paraoxon, was perhaps produced as a result of the heating process. A change in the microsomal incubation method or in the type of AChE assay used could possibly improve this model as an OP toxicity testing tool. The tissue culture model involved exposing primary cultures from chick embryo neurons to methyl parathion. AChE activity as well as cell viability was measured in this investigation. The tissue culture model proved useful, as there was a dosed related inhibition of AChE when testing for AChE inhibition caused by methyl parathion. However, this model was not useful when the toxic endpoint chosen was lethality because cell death did not correlate with AChE inhibition. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Toxicology." |
| Physical Description: | xi, 136 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |