A Biologically-Based Integrated Framework to Assess Metals Bioaccumulation in Aquatic Ecosystems and Human Health Risks
Date Issued
2005
Date
2005
Author(s)
Ling, Min-Pei
DOI
en-US
Abstract
The purpose of this dissertation is to develop a novel biologically-based probabilistic risk assessment (PRA) integrated framework for abalone Haliotis diversicolor supertexta exposed to waterborne zinc (Zn), arsenic (As) exposure estimates for tilapia Orechromis mossambicus, and age-specific human health risks through consumption of As-contaminated farmed seafood and groundwater. The probabilistic models implemented include linking a first-order two-compartment bioaccumulation model, with biokinetic and consumer−resource dynamic models for abalone exposed to waterborne Zn and employing a physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) model not only for describing As exposure in tilapia, but also assessing human health risks. Target organ metal (Zn or As) concentration profiles in aquatic organisms (abalone or tilapia) and human follow a reconstructed dose−response relationship to predict growth and mortality risks of abalone, mortality risk of tilapia, and morbidity and fatality risks for human. This study carries out PRA framework to characterize age-specific exposure risks to ingested inorganic As in BFD-endemic area (through farmed tilapia, milkfish, and large-scale mullet) and in Lanyang Plain (through drinking groundwater and farmed seafood such as smelt and grass shrimp). This study also determines the consumption advice for inorganic As based on the estimates of potential carcinogenic risks. Risk analysis indicates that abalone reared near Toucheng, Kouhu, and Anping, respectively, in north, central, and south Taiwan region show a relative low likelihood that survival is being affected by waterborne Zn. The predicted 90th percentiles of growth HQ (GHQ) for potential growth risk were estimated as 1.94 (Toucheng), 0.47 (Kouhu), and 0.51 (Anping). Expected risks of mortality for abalone were estimated as 0.46 (Toucheng), 0.36 (Kouhu), and 0.29 (Anping). These findings indicate that waterborne Zn exposure poses no significant risk to farmed abalone in Kouhu and Anping, yet a relative high growth risk in Toucheng is alarming. Sensitivity analysis indicated that the key parameter in estimating Zn in algae and abalone is water Zn content that contribution to variance ranged from 82.85 − 91.87%. Risk analysis demonstrates that the probabilities that 10% or more of the tilapia muscle, gill, and liver (risk=0.1) affected ranged from 10-9 to 10-6%, whereas the expected exceedence risk of mortality for tilapia muscle, gill, and liver were calculated to be 0.3, 0.1, and 0.3, respectively, indicating less significant adverse effect for tilapia major organs exposed to waterborne As from selected tilapia farms in the BFD-endemic area. This study performs the health risk for children (4 − 12 yrs, exposure duration: 8 yrs), adolescents (13 − 20 yrs, exposure duration: 16 yrs), and adults (21 − 65 yrs, exposure duration: 61 yrs) consumption of farmed seafood and groundwater by residents in BFD-endemic area and in Lanyang Plain. Risk analysis indicates that consumption of As-contaminated farmed seafood and groundwater from arseniasis-endemic areas may increase threat to prevalence ratios of arsenicosis for all residents and skin cancer for adults, whereas increase potential incidence rates from As-induced lung and bladder cancer for adults. Here this study shows a higher morbidity for arsenicosis and skin cancer and fatality for lung and bladder cancers for residents living in Lanyang Plain. The analysis of the most restrictive risk-based consumption advice, which reflects the highest risks, suggest that the median farmed seafood consumption rate of carcinogenic effects for adolescents (13 − 20 yrs, exposure duration: 16 yrs) is no more than 15 − 28 meals mon-1 (or 25 − 46 g d-1), whereas less than one meal mon-1 (or 0.19 − 0.30 g d-1) for adults (21 − 65 yrs, exposure duration: 61 yrs) in BFD-endemic area. In Lanyang Plain, we suggest that the median consumption rate for adolescents (13 − 20 yrs, exposure duration: 16 yrs) is no more than 4 − 7 meals mon-1 (or 6 − 11 g d-1), whereas less than one meal mon-1 (or 0.08 − 0.12 g d-1) for adults (21 − 65 yrs, exposure duration: 61 yrs).
Subjects
九孔
吳郭魚
年齡別
鋅
砷
機率
生理為基礎之藥理動力及藥理動態
模式為基礎之風險評估
飲食忠告
Abalone
Tilapia
Age-specific
Zinc
Arsenic
Probabilistic
PBPK/PD
Model-based risk assessment
Consumption advice
SDGs
Type
thesis
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