Chromium - Toxicology of Metals - page 488

“relative frequency” of the cause of specifi c death
rates in the white male U.S. population was used as
reference. Total number of deaths was 202, which was
expected, of which 50 were from cancers versus 36.9
expected ( P = 0.05), of whom 21 were from respiratory
cancer (ICD 160-164) versus 11.4 expected ( P = 0.01).
Other authors (Boice et al ., 1999) performed a study
among 3634 airplane spray painters who had been
exposed to concentrations of Cr(VI) encountered at
the workplace in the 1950s and 1960s. This study
revealed no excesses of cancer that could be linked to
Cr(VI) exposure, and the estimated air concentrations
of Cr(VI) seemed to have been very low compared
with other groups of workers exposed to Cr(VI) in the
1940s-1960s.

( P = 0.06). Air measurements in the plant in 1975 docu-
mented the presence of both Cr(III) and Cr(VI) in the
work environment, containing 0.01-0.29 mg/m 3 Cr, of
which 11-33% was water-soluble Cr(VI). In a subse-
quent study, 8 more years of observation was added to
the same cohort (Langård et al ., 1990) by unchanged cri-
teria for inclusion, except that entries between January
1960 and December 1964 were added, which expanded
the cohort to 1235 subjects. Results were presented
separately for the 976 workers studied earlier, in which
observed cancers from all sites had increased from 64
(Exp = 79.4) to 124 (Exp = 144.9), of which 17 were lung
cancers (Exp = 17.8). The incidence for lung cancer
was high in the subgroup of ferrochromium workers;
10 cases observed versus 5.7 expected (95% CI = 4.8-
18.4). The RR for cancer of the prostate (31/26.6) had
declined from the fi rst study. In the population that
included recruits from 1960 to 1964 ( n = 1235), 357
deaths had occurred (E = 440.6; SMR = 91), and SIR for
all cancers was 84 (O/E = 132/157.3). Enhanced risk of
lung cancer was observed in the ferrochromium sub-
group ( n = 379), O/E-ratio = 10/6.5 (SIR = 154; absolute
risk = 95 × 10 −5 /year). The observed/expected (O/E)
ratio for lung cancer in the ferrochromium group
was 3.0 (99% CI = 1.1-6.4) when applying all nonfer-
rochromium workers as an internal reference. Five of
a total of nine cases of kidney cancer had occurred in
the ferrochromium group (SIR = 273), with a mean of
39 years from fi rst employment, whereas the mean
latency time for all nine cases was 37.3 years.

7.3.2.4 Ferrochromium Manufacture
A study among workers in a Swedish plant manu-
facturing ferrochromium alloys from chromite, was
carried out by Axelsson et al . (1980). Males employed
for 1 year+ from January 1930 to December 1975 were
included and were categorized by work duration and
site. Deaths from cancer were obtained from the national
Central Bureau of Statistics, and cancer incidences
were collected manually from the Cancer Registry of
Sweden. The expected deaths and cancer incidence
were computed by a life-table method. A 15-year latent
period from start of employment was accounted for.
In all, 1876 workers were included; 380 were deceased
(383.3 expected) of whom 69 were from cancer (76.7
expected). Five lung cancer cases (ICD 162-163) were
observed versus 7.2 expected. The observed/expected
ratio was 18/20 for cancer of the digestive tract (ICD,
151-153). Maintenance workers were the only group
with excess cancer of the respiratory organs; four
cases (E = 1.0), of which two were mesotheliomas. One
mesothelioma case also occurred among arc furnace
workers where asbestos was used for insulation. Air
levels of Cr(III) ranged from 0.0-2.5 mg/m 3 and for
Cr(VI) levels from 0.0-0.25 mg/m 3 . No information on
smoking was given.
A parallel study in Norway among ferrochromium
and ferrosilicon furnace workers (Langård et al ., 1980)
included all workers employed at the plant for 1 year+
from 1928 and onward, allowing for latency through
exclusion of entries after 1960. Observed and expected
cancers and deaths for the 976 males were both
derived from national data. There were 182 deaths
versus 228.2 expected, and the observed/expected
fi gures for all cancers were 64/79.4. Nine lung cancer
cases were observed (E = 9.45) of which 7 (E = 3.1) were
in the ferrochromium group (absolute risk = 92 × 10 −5 /
year) ( P = 0.08). The expected fi gure for lung cancers
was reduced to 1.8 when using local reference rates

7.3.2.5 Uses of Chromium Compounds
7.3.2.5.1 Chromium Electroplating A mortality stu-
dy was carried out among previous and current Cr
electroplaters with 3 months+ employment in 54
Cr electroplating plants in Yorkshire, U.K. (Royle,
1975a,b), including 1056 male and 182 female platers
142 of whom were deceased as of May 1974. A reference
group matched for age, gender, and smoking habits
was recruited, comprising non-Cr-plating past and
current workers of two industrial companies located
in the same area. Work and smoking histories were
compiled through a questionnaire among 997 live
platers and 1117 live subjects from the reference
group. The platers had experienced a signifi cant excess
of deaths from all cancers; 51 observed versus 24 in
the reference group ( P < 0.01), of which there were 24
lung cancer deaths in male platers versus 13 expected
(not signifi cant). The mean development time from
fi rst exposure to death for lung cancer was 13.6 years
compared with 16.4 years for all cancer deaths. Cancer
of the digestive tract in males was also in excess; 8
observed versus 4 expected (not signifi cant). A larger
proportion of the reference group than the study group