From: Rosalind Schoof
Sent: Wed Feb 23 16:50:15 2011
To: waterqualitystandards
Subject: Arsenic Rulemaking Public Comment
Importance: Normal
The following are my personal comments on the proposed arsenic rulemaking:
I would like to commend DEQ for proposing a science-based approach to revising the arsenic AWQC for protection of human health. I have published several articles that support DEQ’s approach. Regarding the inorganic proportion factor, I evaluated the available data as of 2006 and concluded that for freshwater fish, 10% is a health protective assumption. A similar evaluation yielded 2% as an appropriate proportion for marine fish and crustaceans, and 3% for molluscs. The reference and abstract appear below and I would be happy to supply a copy of the article to any individual working on this evaluation. Based on my findings, I recommend that DEQ retain the IF of 10% for freshwater fish, and reduce the IF for saltwater fish to 2%.
Schoof, R.A., and J.W. Yager. 2007. Variation of total and speciated arsenic in commonly consumed fish and seafood. Hum. Ecol. Risk Assess. 13:946-965.
ABSTRACT:
This paper compiles available data and presents an approach for predicting human intakes of inorganic arsenic (Asi), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) from marine, estuarine, and freshwater seafood when only total arsenic (Astot) concentrations are reported. Twenty studies provided data on total arsenic (Astot) and Asi. Mean Asi concentrations were approximately 10 to 20 ng/g wet weight (ww) in freshwater, anadromous, and marine fish, while crustaceans and molluscs had mean Asi concentrations of 40 to 50 ng/g ww. Thirteen studies provided data for MMA and DMA. MMA was seldom detected, while DMA averaged 10 ng/g ww in freshwater fish, and 45 to 95 ng/g ww in anadromous fish, marine fish, crustaceans, and molluscs. There was little correlation between Astot concentrations and Asi concentrations; however, when only Astot data are available to assess health risks from arsenic in seafood, these data could support conservative, upper end estimates of the percent of Astot likely to be Asi. For marine and estuarine fish, and crustaceans and molluscs 2-3% of Astot was Asi at the 75th percentile of the dataset. For freshwater fish Asi was 10% of Astot at the 75th percentile. Due to the nonlinearity and low carcinogenic potency of DMA, the reported DMA concentrations should not contribute substantially to potential health risks from arsenic in seafood.
I also participated in an assessment of arsenic bioaccumulation in freshwater fish. This research suggested that ambient arsenic concentrations in surface water have little influence on total arsenic concentrations in fish. I support DEQ’s proposal to reduce the BCF, but note that ongoing research will provide additional insight to arsenic bioaccumulation in fish, and DEQ may want to revisit this issue in the future. My article and abstract follow.
Williams, L., R.A. Schoof, J.W. Yager, and J.W. Goodrich-Mahoney. 2006. Arsenic bioaccumulation in freshwater fishes. Hum. Ecol. Risk Assess. 12(5):904-923.
ABSTRACT
The arsenic Ambient Water Quality Criterion 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 upon two datapoints for oysters and fish that was proposed by EPA 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 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.
Rosalind A. Schoof, PhD, DABT
Principal
ENVIRON
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