Detoxification and bioregulation are critical for long-term waterborne arsenic exposure risk assessment for tilapia |
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Authors: | Jeng-Wei Tsai Ying-Hsuan Huang Wei-Yu Chen Chung-Min Liao |
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Institution: | (1) Department of Post-Modern Agriculture, MingDao University, 52345 Changhua, Taiwan, Republic of China;(2) Department of Bioenvironmental Systems Engineering, National Taiwan University, 10617 Taipei, Taiwan, Republic of China; |
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Abstract: | Long-term metal exposure risk assessment for aquatic organism is a challenge because the chronic toxicity of chemical is not
only determined by the amount of accumulated chemical but also affected by the ability of biological regulation or detoxification
of biota. We quantified the arsenic (As) detoxification ability of tilapia and developed a biologically based growth toxicity
modeling algorithm by integrating the process of detoxification and active regulations (i.e., the balance between accumulated
dose, tissue damage and recovery, and the extent of induced toxic effect) for a life span ecological risk prediction. Results
showed that detoxification rate (k
dex) increased with increasing of waterborne As when the accumulated metal exceeded the internal threshold level of 19.1 μg g − 1. The k
dex values were comparable to or even higher than the rates of physiological loss and growth dilution in higher exposure conditions.
Model predictions obtained from the proposed growth toxicity model were consistent with the measured growth data. The growth
toxicity model was also used to illustrate the health condition and growth trajectories of tilapia from birth to natural death
under different exposure scenarios. Results showed that temporal trends of health rates and growth trajectories of exposed
fish in different treatments decreased with increasing time and waterborne As, revealing concentration-specific patterns.
We suggested that the detoxification rate is critical and should be involved in the risk assessments framework. Our proposed
modeling algorithm well characterizes the internal regulation activities and biological response of tilapia under long-term
metal stresses. |
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