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ABSTRACT
The arsenic ambient water quality criterion (AWQC) for protection of human health via ingestion of aquatic organisms is currently 0.14 µg/L. This AWQC is derived using a bioconcentration factor (BCF) of 44, which is a consumption-weighted average based on two data points for oysters and fish that was proposed by the U.S. Environmental Protection Agency in 1980 for broad application to freshwater and marine environments. This BCF is based on the assumption that bioaccumulation is a simple linear function of the exposure concentration. In the nearly quarter of a century since this BCF was promulgated, there have been additions to the arsenic bioaccumulation database and a broader scientific understanding of bioaccumulation mechanisms and how they can be applied to estimating tissue concentrations in aquatic organisms. From this database, we identified 12 studies of arsenic bioaccumulation in freshwater fishes in order to explore differences in laboratory-generated BCFs and field-generated bioaccumulation factors (BAFs) and to assess their relationship to arsenic concentrations in water. Our analysis indicates that arsenic concentrations in tissue and arsenic BAFs may be power functions of arsenic concentration in water. A power function indicates that the highest BCF values may occur at low background levels and may decrease as environmental concentrations increase above the ambient range.
Key Words: arsenic, bioaccumulation, ambient water quality criteria, fish consumption.
INTRODUCTION
The ambient water quality criteria (AWQC) for arsenic for protection of human health are currently 0.14 µg/L, for ingestion of fish alone and 0.018 µg/L for ingestion offish and water. These values are at or below background concentrations for arsenic in fresh, estuarine, or marine water. Consequently, there is current regulatory and scientific interest in re-evaluation of the methods and assumptions that were used to establish the arsenic AWQC in 1980 (USEPA 1980a,b).
Major assumptions used in 1980 to derive AWQC for arsenic concern its bioaccumulation in fish and invertebrates, and its subsequent transformation by aquatic organisms to presumably less toxic organic compounds. This article reviews the current status of arsenic bioaccumulation in the development of AWQC, summarizes recent information on bioaccumulation in freshwater fish, and proposes an inverse relationship between arsenic concentrations in water and bioaccumulation. Issues related to arsenic speciation in species frequently consumed by humans will be addressed in a subsequent article.