A comparative study of an accelerated life‐test model and a toxicokinetics‐based model for the analysis of Porcellio scaber survival data

Abstract

Statistical models have long been used for reliability analysis and risk assessment. In the present study, an accelerated life-test model was used to analyze a set of dose-time-response data obtained with the terrestrial isopod Porcellio scaber. Survival data were experimentally obtained by exposing P. scaber to diazinon (a nonpersistent insecticide) at six concentrations between 2 and 11.31 microg/g (toxicant/soil). Survival data are presented on a weekly basis. The accelerated life-test model assumed a log-normal distribution and constant variance across all diazinon concentrations. Model parameters were obtained by maximum likelihood estimation. The accelerated life-test model was compared to a toxicokinetics-based model reported in the literature. Survival predictions made by both models were compared with the observed data. Both the accelerated life-test model and the toxicokinetics-based model underestimated toxicity at a diazinon concentration of 8 microg/g. Overall, however, the accelerated life-test model outperformed the toxicokinetics-based model, with survival predictions closer to the observed data in most cases and a stronger correlation between predicted and observed survivals. However, as a statistical model, the accelerated life-test model did not reveal mechanistic information, and only statistical and distributional interpretations of its model parameters could be made.

Diagnostics to assess toxicokinetic–toxicodynamic models with interval‐censored data

“…Alternatively, survival analysis methods can be applied to environmental risk and ecotoxicology (Newman and Aplin, 1992;Zhao and Newman, 2004;Ren, 2004;Jager et al, 2011). These methods use concentration-time-response data in which the time of death (perhaps right-censored, i.e., survivors of exposure) is recorded.…”

Toxicokinetic-based survival model for analysis of toxicity data with changing dose

“…Because of the similarity of dose-time-response data from toxicity study and medical study, the survival analysis models were currently used to analyze toxicity data. Parametric survival analysis models, especially accelerated failure time (AFT) models, were employed in several toxicity data analysis with satisfying performance Ren, 2004). The survival analysis method has more statistical power and more flexibility than the LC S0 method, plus the ability to predict survival rate at different time.…”

“…Recently, survival analysis methods have been applied to environmental risk and ecotoxicology (Newman and Aplin, 1992;Henryon et al, 2002;Ren, 2004). These methods make use of dose-time-response data.…”