Selenium Standards Misinterpret Key Research

The EPA proposed a selenium standard for fish tissue of 7.9 ppm, which scientists argue is based on a faulty reading of a study by Dennis Lemly. The error involved an incorrect assumption about sample size, leading the EPA to underestimate fish mortality rates. Despite protests from over 90 scientists and a recommendation for a 5.85 ppm limit, the EPA maintained the 7.9 ppm standard in its 2004 draft, potentially benefiting the coal-mining industry at the expense of aquatic ecosystems.

• The EPA proposed a selenium standard for fish tissue concentrations of 7.9 ppm, which scientists claim is too high to protect aquatic life and could be devastating to stream ecosystems.
• The EPA's 7.9 ppm standard resulted from a misinterpretation of a study by U.S. Forest Service toxicologist Dennis Lemly; the EPA incorrectly assumed a constant sample size of 210 fish, which made it appear that fewer fish died at a given selenium level than actually occurred.
• The proposed standard is criticized for assuming an acceptable mortality rate of 20 percent, whereas the EPA had previously maintained sub-lethal effects of contaminants under 10 percent.
• Dennis Lemly and four U.S. Department of Interior experts recommended a permissible selenium tissue level of 5.85 ppm, a position supported by at least 90 other scientists and professors.
• The coal-mining industry attempted to use the misinterpreted Lemly study to encourage West Virginia to adopt weaker selenium standards.

APA

Union of Concerned Scientists (2004). Selenium Standards Misinterpret Key Research. https://www.ucs.org/resources/attacks-on-science/selenium-standards-misinterpret-key-research

Chicago

Union of Concerned Scientists. Selenium Standards Misinterpret Key Research. 2004. https://www.ucs.org/resources/attacks-on-science/selenium-standards-misinterpret-key-research.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=Selenium Standards Misinterpret Key Research |date=11 April 2004 |url=https://www.ucs.org/resources/attacks-on-science/selenium-standards-misinterpret-key-research |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2004selenium, author = {{Union of Concerned Scientists}}, title = {{Selenium Standards Misinterpret Key Research}}, institution = {Union of Concerned Scientists}, year = {2004}, month = apr, url = {https://www.ucs.org/resources/attacks-on-science/selenium-standards-misinterpret-key-research}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }