RIASSUNTO
Abstract
The 1993 U.S. Environmental Protection Agency (EPA) Gulf of Mexico General Discharge Permit (GMG290000), required operators to conduct an offshore produced water bioaccumulation study. The goals were to assess the potential for bioaccumulation to marine organisms of selected target compounds associated with produced water, and to evaluate the human health risk to seafood consumers. Eighty-nine Offshore Operators Committee member companies cosponsored this three year, $3,000,000 study from 1994 through 1997.
The study was based on pairwise comparisons of chemical concentrations in edible tissues of marine organisms collected near 12 platforms discharging >4,600 barrels per day (bpd) >548 m3/day) and 12 non-discharging platforms. Twelve target analytes were measured at all locations. These included three volatile organics, four semi-volatile organics, three metals, and two radionuclides. Two of these platform pairs were studied in great detail (larger numbers of specimens and an additional 48 target analytes were measured). Spring and summer sampling cruises were made to collect biota, produced water, and ambient seawater. Eleven species of fish were collected, three species of mollusks, and one species of crustacea. Sampling areas included shallow and deep water, areas of high and low industry activity, and near river locations. The results showed no significant bioaccumulation related to the produced water discharges.
The extensive literature review conducted as part of this study on toxic response and tissue residues of target analysts in marine organisms, showed that none of the EPA specified target analytes were present at concentrations that might be harmful to the fish or bivalve mollusks. A comparison of tissue concentrations to risk based concentration factors in humans is indicative that there is no human health risk to consumers of fisheries products harvested from the vicinity of platforms discharging produced water. Based on this comprehensive study, it appears that produced water discharges into U.S. waters under the current regulatory requirements, do not pose an unacceptable risk to the environment or human consumers.