Hexavalent Chromium Regulatory History
This page updated June 17, 2004.
Board identified hexavalent chromium as a toxic air contaminant (TAC)
in January 1986. The Board found, based on epidemiological and animal
studies, that hexavalent chromium should
be considered a human carcinogen for which there is no safe threshold
exposure level. At that time, the Department
of Health Services (DHS) predicted a theoretical excess cancer risk of
up to 146 in one million for a 70-year exposure
to 1 ng/m3 of hexavalent chromium. This finding was consistent with
that of the Scientific Review Panel on Toxic
To reduce the health risks from hexavalent chromium emissions, the Board has already taken steps to reduce emissions. In 1988, an Airborne Toxic Control Measure (ATCM) was adopted to reduce hexavalent chromium emissions from both decorative and hard chrome plating facilities, as well as chromic acid anodizing operations. This measure reduced overall emissions from these facilities by 97 percent. The emission standards have been met by utilizing add-on pollution control devices such as High Efficiency Particulate Air (HEPA) filters, packed bed scrubbers, and/or by adding fume suppressants to the plating tanks.
In 1998, the ATCM for Chrome Plating and Chromic Acid Anodizing operations was amended to establish equivalency with federal standards. These amendments did not change the limits already in place, but established separate limits for new sources. The 1998 amendments to the ATCM continued to divide hard chrome plating operations into three tiers (Large/Medium/Small) for existing sources, but established two tiers (Large and Medium/Small) for new sources. For hard chrome plating, the ATCM requires operations to comply with an emission limitation expressed in terms of milligrams of hexavalent chromium emissions per ampere-hour (mg/amp-hr). The applicable emission limitation depends on the chrome plating source size (both in terms of mass emissions and ampere-hour usage). The largest hard chrome plating operations must meet a control efficiency of over 99 percent. Decorative chrome plating and chromic acid anodizing facilities are required to use chemical or mechanical fume suppressants to reduce hexavalent chromium emissions by 95 percent.
In addition to emission requirements, chrome plating and chromic acid anodizing operations are required to conduct a performance test to demonstrate compliance. The ATCM also requires regular inspections and maintenance, parameter monitoring, operation and maintenance plans, and recordkeeping.