Guidelines for Metals and Metalloids in Ambient ... - ARCHIVE: Defra

Chromium
5.3.4.2 Human studies
272. There is a large body of evidence from the USA, Europe and the far
East associating occupational exposure to chromium compounds with
lung cancer, and, more rarely, nasopharyngeal cancer (ATSDR, 2000;
Hayes, 1988; USEPA, 1998). The most consistent associations have
been observed among workers in the chromate production and
chromate pigment industries. Risks of lung cancer increase with the
intensity and duration of exposure and the strength of association
makes it unlikely that the results are due to uncontrolled confounding
by cigarette smoking or other factors. Studies of workers in the chrome
plating industry have found less consistent associations and studies of
workers engaged in stainless steel welding and ferrochrome alloy
production have been inconclusive.
273. A review of the largest and best-designed studies of occupational lung
cancer, to date, was published in 1996 (Steenland et al., 1996).
The information from these was used to estimate the range of excess
deaths across five levels of exposure (SCOEL, 2004); the findings are
summarised in Table 5.2.
Table 5.2: Estimated excess numbers of lung cancer deaths by exposure intensity to
hexavalent chromium compounds.
Working-life exposure to various hexavalent
chromium compounds
Excess number of deaths from lung cancer
(range)
50 µg/m 3
5-28
25 µg/m 3
2-14
10 µg/m 3
1-6
5 µg/m 3
0.5-3
1 µg/m 3 0.1-0.6
274. Occupational exposures are generally to both Cr(III) and Cr(VI) with
the possibility in some occupations of co-exposures to other
substances such as nickel. Toxicological studies show that Cr(VI) is
carcinogenic but that Cr(III) is less so, if at all (IARC, 1997). For this
reason it is widely accepted that the increased risk of cancer in
occupational studies is attributable to Cr(VI). It should be noted that
Mancuso (1997) in a study of chromate workers in Ohio, concluded
that cancer was also associated with exposure to Cr(III), but this
conclusion has been questioned. In the leather tanning industry, where
exposure is mainly to Cr(III), studies in the USA, UK and Germany
have reported no increased risk of cancer.
275. There is a lack of informative studies of the effects of community
exposures to airborne chromium. A single report of a study of the
population living near a ferrochrome alloy plant in Sweden found no
excess risk of lung cancer (Axelson and Rylander, 1980).
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