Document Type

Article

Publication Date

5-2003

Abstract

Recent studies on potential mercury (Hg) contamination of fish from East Texas lakes and waterways have caused concern about mercury levels in East Texas waters. Historical records of Hg concentrations in 33 East Texas streams showed that median concentrations for each stream segment were no different than other U.S. streams. All the means and medians for stream segments having at least 20 recorded measurements were less than Texas (2.4 µg/L) water quality standards. Water samples collected in December 1995 and March 1996 from 6 different stream sites in Nacogdoches County had concentrations similar to historical records. Due to biological magnification, fish Hg levels can be 20,000 times greater than water Hg levels and levels are greater in large fish than in small fish. Although a recent study on sediment cores in 13 East Texas reservoirs and lakes suggested possible increases in mercury concentrations across the region, all Hg concentrations in water and sediment were far below Texas acute and chronic quality standards. No significant correlations were found between fish mercury concentrations and mercury concentrations in water or sediment. Potential agricultural inputs of Hg in East Texas are very low; the most likely source of Hg is atmospheric deposition from fossil fuel combustion and other industrial practices. The following may be considered to minimize potential health risks: 1) consume smaller fish from a variety of waterbodies, 2) increase consumption interval, 3) avoid eating skin and fatty tissues, and 4) limit consumption to quantities recommended by the Texas Health Department.

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