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CHROMIUM (HEXAVALENT)
CAS No: 18540-29-9
I. PHYSICAL AND CHEMICAL PROPERTIES (From HSDB, 1998)
Molecular weight 51.966
Boiling point 2642 °C
Melting point 1900 °C
Vapor pressure 1 mm Hg at 1616 °C
Air concentration conversion not available
II.
HEALTH ASSESSMENT VALUES
Unit Risk Factor: 1.5 E-1 (µg/m 3 ) -1
Slope Factor: 5.1 E+2 (mg/kg-day) -1
[Human lung cancer mortality data (Mancuso, 1975), linearized multistage procedure, extra risk
(US EPA, 1984), reevaluated by CDHS (1985).]
Oral Slope Factor: 4.2 E-1(mg/kg-day) -1
[Calculated by CDHS (1991) from female mouse benign and malignant stomach tumor data
(Borneff et al., 1968), using a linearized multistage procedure.]
III.
CARCINOGENIC EFFECTS
Human Studies
Several reviewers have summarized the epidemiologic studies examining the effects of chromium
exposure on cancer morbidity and/or mortality (IARC, 1980; Hayes, 1982; US EPA, 1984). The
chromium Toxic Air Contaminant (TAC) document (CDHS, 1985) included a summary table listing 14
occupational studies reporting an increase in cancer morbidity and/or mortality (primarily but not
exclusively lung cancer). At the time the chromium TAC document was released, the relevant studies
with exposure data were those by Pokrovskaya and Shabynina (1973, as cited in US EPA, 1984),
Mancuso (1975) and Langard et al. (1980).
Pokrovskaya and Shabynina (1973) compared the cancer mortality of a group of ferroalloy workers in
the Soviet Union to the local population for the time period 1955-1969. No specific cohort was
defined nor were the number of cancer cases, individuals in the comparison groups, or person-years at
risk given. Workers in the plant were reported to be exposed to low-solubility chromium compounds
with concentrations of hexavalent chromium exceeding the allowable level of 0.01mg/m 3 by 2 to 7 times.
In addition, some workers were exposed to smelting process fumes for the chromium ore, which
included benzo[a]pyrene.
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