Chromium - Toxicology of Metals - page 485

reporting on 12 lung cancer deaths, versus 3.3 expected.
Smoking and other possible confounders could explain
the increased death rates.
Ohsaki et al . (1978) reported on 14 cases of lung
cancer among 133 male workers with 10 years' expe-
rience at a Japanese chromate manufacturing plant
between 1936-1973 stated to have been exposed to
Cr trioxide, sodium dichromate, potassium dichro-
mate, and water-soluble Cr(III) compounds. Dura-
tion of employment ranged from 10-36 years and
age at diagnosis ranged from 27-64 years (mean,
50.3 years). Twelve of the case subjects were con-
firmed to be smokers. Eleven of 17 cases reported by
Zober (1979) had worked in alkali-chromate man-
ufacturing, only three of whom were reported to
have undergone exposure to Cr(III); however, there
was no documentation on absence of exposure to
Cr(VI).
Twenty cases of lung cancer among chromate manu-
facturing workers were reported on by Abe et al . (1982),
of which all but fi ve had occurred in heavy smokers.
Tsuneta (1982) reported on 25 lung cancer cases that
had occurred in male workers in a chromate plant, and
the abstract reported that the lung cancer incidence
was 413 × 10 −5 /year, 16 times in excess of that of the
general population. The average employment time at a
chromate plant was 21.5 years, whereas the average
time between fi rst exposure to chromates and cancer
was 25.4 years.
A number of studies have reported on the content
of Cr in lung tissue in previous chromate workers
with lung cancer (Hyodo et al ., 1980; Kim et al ., 1985;
Kishi et al ., 1987). None of these studies succeeded in
explaining exposure-response relationships.

increased from SMR 144.6-649.6 in fi ve exposure cat-
egories ranging from 0.25-0.49 to 4.0+ mg/m 3 , and
from 80.2-998.7 at exposures ranging from <0.25 to
2.0+ mg/m 3 for insoluble Cr(III) and soluble Cr(VI),
respectively. The corresponding SMR for assumed
exposure to total Cr concentrations increased from
225.7 in the 0.50-0.99 mg Cr/m 3 category to 741.5
in the 6.0+ mg/m 3 category. At a given air concen-
tration of Cr, increased levels of total Cr resulted in
an enhanced death rate from lung cancer in four of
the fi ve exposure categories. For exposure to total
Cr, increasing air levels of insoluble Cr resulted in a
declining death rate from lung cancer in three of the
fi ve categories. No corresponding analysis was pre-
sented for the possible relationship between a given
exposure to total Cr and increasing concentrations
of soluble Cr.
Mancuso (1997) revisited the preceding cohort
using limited exposure data from an earlier analysis
(Mancuso, 1975). A study was later carried out (Luip-
pold et al., 2003), with follow up to 1997, which was
based on the same recruitment cohort (Mancuso, 1975)
but with altered inclusion criteria, studying only those
with more than 12 months of employment after 1940.
These authors stated that no exposure data for triva-
lent chromium were identifi ed in the historical fi les.
They found that the excess lung cancer was linked to
the cohort fi rst employed before 1960, when the plant
used a high-lime mixture in their process, assumed to
result in exposure to calcium chromates.
Hayes et al . (1979) examined whether workers
employed in sections of the plant constructed to reduce
hazardous exposures revealed a declining risk of res-
piratory cancer compared with workers employed in
an old facility. The cohort comprised 2101 workers,
all fi rst employed between 1945 and 1974 and with
90 days+ employment. Subjects for whom vital status
was ascertained as of July 1977 (i.e., 88% of the cohort;
n = 1803) were included in the analyses. As reference,
entity, age-, race-, and time-specifi c male mortality
rates of the city of Baltimore were applied. On the
basis of 59 observed deaths, the SMR for cancer of the
trachea, bronchus, and lung (ICD 162) was 202 (95%
CI = 155-263), versus 29.2 expected. SMR for lung can-
cer was 180 (95% CI = 110-270) on the basis of 20 deaths
for employees hired between 1945 and 1949 with less
than 3 years work. Those with 3 years+ of work, hired
between 1945 and 1949, presented an SMR of 300 (95%
CI = 160-520) on the basis of 13 deaths. The SMR for
lung cancer on the basis of two deaths was 70 in work-
ers hired 1950-1959 with less than 3 years work at the
new facility. Workers hired between 1950 and 1959
and employed less than 3 years at the older facility
presented an SMR of 180 (95% CI = 90-310) on the basis

7.3.2.2 Chromate Manufacture
The studies by Taylor (1966) and Enterline
(1974) presented strong evidence on the association
between Cr(VI) exposure and lung cancer. Man-
cuso (1975) reported on the mortality of a cohort
recruited from a chromate-manufacturing plant
that he had studied before (Mancuso and Hueper,
1951). Industrial hygiene data available from 1949
were used to calculate weighted average air con-
centrations of water-soluble, insoluble, and total
Cr, respectively. The mortality rates for the subco-
hort recruited between the years 1931and 1937 were
calculated for dose/time categories, and analysis
was limited to 41 lung cancer deaths that occurred
in this cohort during 1931-1974. The standardized
mortality ratios (SMRs) were compared with those
of the entire plant population. Deaths from lung
cancer were clustered in workers with 27-36 years
since fi rst employment. Death rates for lung cancer