Inhibition, Acetylcholinesterase (AchE) leads to Decreased, Population trajectory
Upstream eventInhibition, Acetylcholinesterase (AchE)
Decreased, Population trajectory
Key Event Relationship Overview
AOPs Referencing Relationship
|AOP Name||Adjacency||Weight of Evidence||Quantitative Understanding|
|Acetylcholinesterase inhibition leading to acute mortality||non-adjacent||Low||Low|
Life Stage Applicability
Key Event Relationship Description
Evidence Supporting this KER
Include consideration of temporal concordance here
- Macek and coworkers conducted a pond study to evaluate the effects of chlorpyrifos applied at a rate intended to control insects, and observed significant impacts on fish species (bluegill and largemouth bass) with the highest application rate resulting in cumulative mortalities ranging from 46-55% with 80% AChE inhibited after 7 days (Macek et al., 1972). The researchers noted that the effects observed in the field exposure were more sensitive than those reported in controlled laboratory studies. The authors postulated that the differences may be due to affects not typically observed in a controlled laboratory study. They presented data where the fish, especially the bluegill, fed heavily on the invertebrates in the first 7 days of the study thereby compounding the exposure that in the laboratory would be only via water. In addition, the invertebrate population collapsed (90% reduction) during an extended observation period, and this may have contributed to the overall mortality in fish after the chemical exposure had ended (Macek 1972).
- Increased sensitivity was observed in second generation fish (Pimephales promelas) exposed after hatch to chlorpyrifos (Jarvinen et al., 1983). Biomass of the second generation fish recruitable to the population was estimated using a model that assumed a normal distribution for the population and used total egg production, hatchability, survival, and fish weight as input variables. The model estimated a significant reduction in the recruitment population (Jarvinen et al., 1983).
Uncertainties and Inconsistencies
Quantitative Understanding of the Linkage
- We are unaware of any quantitative relationships suitable for extrapolating from acetylcholinesterase inhibition to altered population trajectory.