manufacture, processing and use of stainless steel - International ...

testing. The former study was poorly conducted and contributes no reliable data. The
latter study, although deficient in several respects, provides no evidence for the
carcinogenicity of the MMA/SS welding fume tested.
Human data
Milatou-Smith et al. 1997
Mortality in two cohorts of welders was investigated by Milatou-Smith et al. (1997).
This paper includes the follow-up of an earlier study by Sjögren et al. (1987). One
cohort comprised 233 males with at least five years experience of welding stainless
steel during the period 1950-1965. Most of the subjects had welded using coated
electrodes (i.e. MMA welding); a small number had used the TIG method. The
second cohort comprised 208 railway track welders, with at least five years
experience during the same period. Both cohorts were followed through to 1992. The
first cohort was reported as having high exposure to Cr VI relative to the second cohort.
The only exposure data presented were from a national survey of welders in 1975;
median TWA “chromium” levels for MMA welding were reported to be 110 µg/m 3 ,
with maximum levels of 750 µg/m 3 . It is assumed that these values refer to total
chromium, although this is not stated. There were no exposure data which
specifically related to subjects in this study. Expected numbers of deaths were based
on national mortality rates, adjusted for age, sex and calendar period.
In the “high exposure” cohort, overall mortality was less than expected (Observed 60,
Expected 76.1, SMR 79, 95% CI 60 to 102). There were six lung cancer deaths in
this cohort (Expected 3.65, SMR 164, 95% CI 60 to 358). In the “low exposure”
cohort, both overall mortality and lung cancer mortality were below the expected
incidence. There were 80 deaths (all causes) in this cohort compared to 110 expected
(SMR 73, 95% CI 58 to 91), and two lung cancer deaths (Expected 4.88, SMR 41,
95% CI 5 to 148). With both cohorts, exposure to asbestos may have occurred,
although the study authors assume that exposure to asbestos was “very low”.
This study indicated a non-significant excess of lung cancer among MMA/SS
welders, although the cohort size was small. An association between these lung
cancers and exposure to welding fume remains uncertain. Further, possible
involvement of asbestos cannot be excluded.
Becker et al. 1991
A cohort mortality study was conducted among 1221 arc welders exposed to fumes
containing nickel and chromium and an internal reference group of 1694 turners
(Becker et al. 1991). All workers were employed at one of 25 factories from the
German metal processing industry; it is not clear whether all 25 factories were
processing stainless steels. All study subjects had worked as either welders or turners
for at least six months in the period 1950-70. The period of observation is not clearly
stated; it would seem to be 1950-88, although the title of the paper which includes the
phrase "results of a second follow up 1983-8" could leave a different impression.
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