Arsenic Bioaccumulation in Freshwater Fishes

ABSTRACT

The arsenic ambient water quality criterion (AWQC) for protection of human health via ingestion of aquatic organisms is currently 0.14 μ g/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.

Keywords:

• arsenic
• bioaccumulation
• ambient water quality criteria
• fish consumption

ACKNOWLEDGEMENTS

Partial funding was provided by the Electric Power Research Institute, Palo Alto, CA. Technical comments provided by Dr. Joe Tomasso of Clemson University and three anonymous reviewers are greatly appreciated.

Notes

¹The oyster data were from unpublished research results from USEPA's Narragansett, Rhode Island Laboratory.

²For example, the rainbow trout data (Spehar et al. 1980) should have yielded BCFs in the range of 5 to 2,500 instead of a BCF of 0 as interpreted by USEPA (1980b).

^a BCFs are calculated as the wet-weight concentration of a chemical in tissue divided by its concentration in water. BAFs are calculated as the ratio of wet-weight tissue concentration divided by water concentration as kg/L at steady-state conditions with all exposure media.

^b Data retrieved from USEPA (2003) database. Total arsenic in water was reported as an average of three monthly samples.

^c Average wet-weight arsenic concentrations in fish tissues for this study were provided by C. Chen (personal communication). Dissolved arsenic concentration in water was averaged from three monthly values presented in Figure 3 of Chen and Folt (2000).

^d 1995–1996 dissolved arsenic concentrations in water were excluded for Schroon Lake because it was reported at 0.000 μ g/L, which is probably a typographical error. 1992–1993 total arsenic concentrations in fish are from EMAP NE Lakes Study.

^e Total arsenic in water was reported. Prey fish were analyzed as whole fish, and game fish were analyzed as separate flesh and viscera samples. Tissue concentrations transformed from dry weight to wet weight by assuming a 75-percent moisture content, which is the average for the NE Lakes Study conducted by EPA's EMAP program.

^f Tissue concentrations were transformed from dry weight to wet weight by assuming a 75-percent moisture content, which is the average for the NE Lakes Study conducted by EPA's EMAP program (http://www.epa.gov/emap/html/dataI/surfwatr/data/index.html).

^g Arsenic concentrations greater than 530 μ g/L in water inhibited fish growth and were eliminated from this evaluation. Arsenic concentrations in fish were presumably based on whole body samples reported in wet tissue weight.

^h Concrete pools in LaCrosse, WI, filled with well water, stocked with adult and immature bluegills, treated with an herbicide containing sodium arsenite. Tissue concentrations presumably reported in wet weight.

ⁱ Assumes arsenic in control water was not detected at 20 μ g/L.

^j Significant reduced body weight at the highest exposure concentration (9,640 μ g/L).