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At this site, the SCDEHC considered issuing a health advisory based on the amount of shellfish consumed per time period, but ultimately decided to issue a ban on shell fishing from portions of Shipyard Creek. This action was generated by the increased levels of chromium detected in shellfish samples from the 1997 study sponsored by NOAA and EPA. The FDA's levels of concern for chromium contaminated shellfish are: 12 ppm for blue crabs and shrimp, and 13 ppm for oysters. The analytical results of shellfish samples obtained from Shipyard Creek showed that 15% of the oysters, 26% of the crabs, and 95% of the shrimp contained chromium that exceeded FDA's levels of health concern. Furthermore, shellfish samples from Shipyard Creek contained chromium at concentrations greater than chromium levels detected in control shellfish samples from outside of Shipyard Creek. Because the average concentrations of chromium detected in oysters and crabs do not exceed FDA's levels of health concern for chromium, chronic consumption of oysters and crabs probably do not pose a health threat given that biological chromium III is relatively non-toxic. However, because the average concentration of chromium (27 ppm) detected in shrimp is two times the levels of FDA's level of health concern, chronic human consumption of shrimp from Shipyard Creek, may pose a health threat because people may consume chromium III at toxic levels.

The purpose of the Federal Food, Drug and Cosmetic Act (FD&C Act)is to ensure a safe and wholesome food supply. The FD&C and other related statutes, including the Public Health Service Act provide the regulatory framework under which the FDA assesses the effects of environmental contaminants on the safety of consumption of fish and shellfish. The FDA has set levels of concern for chromium contaminated fish and shellfish, and these values were used by SCDEHC to evaluate the health implications associated with exposure to shellfish from Shipyard Creek (see Attachment 1).

The data did not indicate what speciation of chromium was detected in shellfish at this site, however, it is assumed that chromium III was detected because chromium VI is reduced biologically to chromium III. Although in general, chromium III is known to be non-toxic, toxicity depends on the dose, and since shellfish in Shipyard Creek contain chromium at concentrations well above FDA's levels of health concern, there may exist a threat to humans who ingest the shellfish on a frequent basis.

Chromium is a naturally occurring element that is distributed in the air, water, soil, and the earth's crust. The trivalent form and its salts are usually the most stable form of chromium and the main form in plants and animals. At this site, the major route of exposure to chromium is ingestion of contaminated shellfish or gastrointestinal absorption. Chromium VI is more easily absorbed across the GI tract than chromium III, however, chromium VI is reduced biologically to chromium III. The toxicity associated with chromium results primarily from industrial inhalation exposure to chromium VI. Chromium VI compounds are classic skin irritants and sensitivities. Laboratory studies have shown that chromium VI may cause cancer development in mice, at the exposure site, however, these data need to be verified.

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