Toxicodynamic modeling of zebrafish larvae to metals using stochastic death and individual tolerance models: comparisons of model assumptions, parameter sensitivity and predictive performance
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Process-based toxicodynamic (TD) models are playing an increasing role in predicting chemical toxicity to aquatic organism. Stochastic death (SD) and individual tolerance distribution (IT) are two often used assumptions in TD models which could lead to different consequences for risk assessment of chemicals. Here, using the toxicity data of single (Cu, Zn, Cd, and Pb) and their binary metal mixtures on survival of zebrafish larvae, we assessed the parameter sensitivity and evaluated the predictive performance of SD and IT models. The sensitivity analysis indicated the parameters related to toxicodynamics such as k k and threshold, had a great influence on the SD model’s output and α had a great influence on the IT model’s output. The predicted survival probability was highly sensitive to the assumptions of SD or IT models, and the SD model explained toxicity of single metal and binary metal mixtures better than IT model. Our results suggested that SD model is more suitable in assessing the metal toxicity to zebrafish larvae. Moreover, different combinations of laboratory metal-specific and species-specific experiments with SD and IT models need further study for better understanding and predicting toxic effects for different metals and organisms.
KeywordsToxicodynamic (TD) model Stochastic death (SD) Individual tolerance distribution (IT) Metal toxicity Predictive power
This study was supported by the National Natural Science Foundation of China (21277076),Tianjin Natural Science Foundation (15JCYBJC22800), the National Water Pollution Control and Treatment Science and Technology Major Project (2012ZX07501003) and the Fundamental Research Funds for the Central Universities. We thank the editor and the two anonymous referees whose comments and suggestions greatly improved the quality of the article.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing interest.
This study involving animals was conducted in accordance with the national and institutional guidelines for the protection of animal welfare.
This is an altruistic study on animals, and we all authors expect that results obtained from this study will enable us to improve the knowledge on heavy metal toxicity and finally may result in useful benefits for society as a whole.
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