Risk assessment models, pyrethroid

Parameters for Pyrethroid Insecticide QSAR and PBPK/PD Models for Human Risk Assessment... 

The sections on the metabolism and neurotoxicity of the pyrethroids in this review provide a starting point that feeds into the physiological and biochemical parameters that are needed to develop PBPK/PD models for assessing risks to the pyrethroids. The development of such pyrethroid model parameters requires knowledge of their discovery, chemistry, chirality, their isomers, and their chromatographic separation. To this end. Sect. 2 above (viz.. Nature of Pyrethroid Insecticides) was developed with a listing of 15 of the most important pyrethroids... 

Recently, metapopulation models have been successfully applied to assess the risks of contaminants to aquatic populations. A metapopulation model to extrapolate responses of the aquatic isopod Asellus aquaticus as observed in insecticide-stressed mesocosms to assess its recovery potential in drainage ditches, streams, and ponds is provided by van den Brink et al. (2007). They estimated realistic pyrethroid concentrations in these different types of aquatic ecosystems by means of exposure models used in the European legislation procedure for pesticides. It appeared that the rate of recovery of Asellus in pyrethroid-stressed drainage ditches was faster in the field than in the isolated mesocosms. However, the rate of recovery in drainage ditches was calculated to be lower than that in streams and ponds (van den Brink et al. 2007). In another study, the effects of flounder foraging behavior and habitat preferences on exposure to polychlorinated biphenyls in sediments were assessed by Linkov et al. (2002) using a tractable individual-based metapopulation model. In this study, the use of a spatially and temporally explicit model reduced the estimate of risk by an order of magnitude as compared with a nonspatial model (Linkov et al. 2002). 

Soderlund et al. (2002) made the following observation The diverse toxic actions and pharmacological effects of pyrethroids suggest that simple additivity models based on combined actions at a single target are not appropriate to assess the risks of cumulative exposure to multiple pyrethroids. ... 

In this review we have examined the status of parameters required by pyrethroid QSAR-PBPK/PD models for assessing health risks. In lieu of the chemical, biological, biochemical, and toxicological information developed on the pyrethroids since 1968, the finding of suitable parameters for QSAR and PBPK/ PD model development was a monumental task. The most useful information obtained came from rat toxicokinetic studies (i.e., absorption, distribution, and... 

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