Assessment of Human Health Risks for Arsenic Bioaccumulation in Tilapia ( Oreochromis mossambicus ) and Large-Scale Mullet ( Liza macrolepis ) from Blackfoot Disease Area in Taiwan

Abstract

This paper carries out probabilistic risk analysis methods to quantify arsenic (As) bioaccumulation in cultured fish of tilapia (Orechromis mossambicus) and large-scale mullet (Liza macrolepis) at blackfoot disease (BFD) area in Taiwan and to assess the range of exposures for the people who eat the contaminated fish. The models implemented include a probabilistic bioaccumulation model to account for As accumulation in fish and a human health exposure and risk model that accounts for hazard quotient and lifetime risk for humans consuming contaminated fish. Results demonstrate that the ninety-fifth percentile of hazard quotient for inorganic As ranged from 0.77-2.35 for Taipei city residents with fish consumption rates of 10-70 g/d, whereas it ranged 1.86-6.09 for subsistence fishers in the BFD area with 48-143 g/d, consumption rates. The highest ninety-fifth percentile of potential health risk for inorganic As ranged from 1.92 x 10(-4)-5.25 x 10(-4) for Taipei city residents eating tilapia harvested from Hsuehchia fish farms, with consumption rates of 10-70 g/d, whereas for subsistence fishers it was 7.36 x 10(-4)-1.12 x 10(-3) with 48-143 g/d consumption rates. These findings indicate that As exposure poses risks to residents and subsistence fishers, yet these results occur under highly conservative conditions. We calculate the maximum allowable inorganic As residues associated to a standard unit risk, resulting in the maximum target residues, are 0.0019-0.0175 and 0.0023-0.0053 microg/g dry weight for tilapia and large-scale mullet, respectively, with consumption rates of 70-10 g/d, or 0.0009-0.0029 and 0.0011-0.0013 microg/g dry weight for consumption rates of 169-48 g/d.

Risk-based assessment of arsenic-affected aquacultural water in blackfoot disease hyperendemic areas

“…To compare with other researches, the risks evaluated in this work are close to a risk range from 2.07 9 10 -6 to 7.89 9 10 -5 reported by Ling et al (2005), but are much lower than a risk range from 7.36 9 10 -4 to 1.12 9 10 -3 reported by Liao and Ling (2003). The unrealistic, high risks estimated by Liao and Ling (2003) result from the use of bioaccumulation factor to estimate As concentrations in tilapia, and the fail to convert the dry wt As concentration to wet wt and to ignore edible portions of tilapia.…”

“…Accordingly, as for the ingestion rate of tilapia, Liao and Ling (2003) reported a questionnaire survey result regarding tilapia consumption for 57 subsistence fishers in the BFD hyperendemic area. The ingestion rate of whole tilapia ranges from 48 to 169 g/day wet wt.…”

“…The sources of surface water include river, sea and rainfall. According to survey Liao and Ling (2003) a N(l a ,r a ) denotes a normal distribution with an arithmetic average of l a and an arithmetic standard deviation of r a b LN(l g ,r g ) denotes a log-normal distribution with a geometric average of l g and a geometric standard deviation of r g c Valid range from 48 to 169 g/day wet wt data published by Taiwan EPA (http://wq.epa.gov.tw/wq/ Public2/ ImageBasin.asp), average As contents in rivers of the BFD hyperendemic regions and the coast range from 4.5 to 9.6 lg/L and from 0.8 to 2.0 lg/L, respectively, during 2002-2006. The As concentration in rainfall can be considered to be nil.…”

“…Additionally, a regulatory standard of As in farmed pond water is 50 lg/L in Taiwan (Taiwan EPA 1998). Arsenic concentrations in many ponds far exceed the standard (Liao and Ling 2003). Moreover, the Taiwanese regulatory standard of As in farmed pond water is lack of scientific evidences to demonstrate that it is no adverse health effects.…”

“…Risk assessment is a frequently employed method which discusses potential threats to human health through an exposure-bioaccumulation-ingestion pathway of toxic substances in aquatic organisms (Pohl et al 2003;Hung et al 2004). Several researches evaluated by the risk assessment approach revealed that the great amount of ingesting tilapia farmed in the BFD hyperendemic area posed a menace to human health (Han et al 1998;Liao and Ling 2003;Liu et al 2005;Ling et al 2005;Jang et al 2006). Additionally, a regulatory standard of As in farmed pond water is 50 lg/L in Taiwan (Taiwan EPA 1998).…”