Chromium and Sludge

Occupational Exposure to Hexavalent Chromium
(c) Permissible exposure limit (PEL). The employer shall ensure that no employee is exposed to an airborne
concentration of chromium (VI) in excess of 5 micrograms per cubic meter of air (5 µg/m³), calculated as an 8 hour time
weighted average (TWA).

1995 EPA action which removed Chromium from the Sludge/biosolid Use Section of Part 503

Section 405(d) of the CWA requires EPA to establish management practices and numerical limits adequate to protect
public health and the environment from reasonably anticipated adverse effects of toxic pollutants in sewage sludge

This concentration is consistent with the total chromium concentration limit established for granting a removal credit for
sewage sludge placed in a
lined active sewage sludge unit.

U.S. DC Circuit Court of Appeals, United States Court of Appeals,   FOR THE DISTRICT OF COLUMBIA CIRCUIT
    Argued October 20, 2003   Decided December 9, 2003,                  No. 02-1326
           Safe Food and Fertilizer  v. Environmental Protection Agency,
    The EPA set its chromium exclusion level at 21.3 ppm for fertilizer with 35.5% zinc content, 67 Fed.
    Reg. at 48,403/3. Of the twenty commercial virgin fertilizer samples reported by the EPA, six included
    test results for chromium. Of these six, one had a chromium concentration of 8 ppm; the other five all
    had chromium concentrations of less than 1 ppm. Data Summary. The EPA's chromium exclusion level
    thus appears to be more than double the highest virgin commercial sample, ten times the commercial
    sample mean, and twenty times the commercial sample median. Given that the EPA has not pointed to
    anything in the record indicating that these differences in chromium concentrations are trivial from a
    health and environment perspective, we cannot affirm on the basis of the identity principle. We
    therefore remand to the agency for an explanation as to whether the differences that its rule allows
    are irrelevant when considered in light of possible effects on human health or the environment.