A meta-analysis of epidemiologic studies of lung cancer in welders

Abstract

Original articles Scand J Work En viron Health 1997;23: 104-13 A meta-analysis of epidemiologic studies of lung cancer in welders Objective A meta-analysis of epidemiologic studies was carried out on lung cancer risk among shipyard, mild steel, and stainless steel welders, and the role of asbestos exposure and smoking was considered. Methods The meta-analysis consisted of calculating combined relative risks (RR) and their variances through a logarithm transformation of published RR values and a weighing using the inverted variance of each RR. Results The literature provided 18 case-referent and 31 cohort studies. The combined RR values were 1.38[observed 1028,95% confidence interval (95% CI) 1.29-1.481 for "all or unspecified welding categories", 1.30 (observed 305, 95% CI 1.14-1.48) for shipyard welders, and 1.35 (observed 173, 95% CI 1.15-1.58) for nonshipyard welders. Similar combined RR values (RR) were observed for mild steel welders (combined RR 1.50, observed 137, 95% CI 1.18-1.91) and stainless steel welders (combined RR 1.50 observed 114, 95% CI 1.10-2.05). No significant heterogeneity was discerned between studies of any welding or study design category. A marked healthy worker effect may also lead to an underestimation of the standardized mortality ratio for lung cancer among stainless steel welders. Furthermore, welders of any category are likely to be exposed to asbestos. Welders also seem to smoke more than the general male population, and therefore the hypothesis of tobacco overconsumption among welders could not be discarded. C O~C~U S~O~S A 3 0 4 0 % increase in the RR of lung cancer among welders cannot be explained by hexavalent chromium and nickel exposure among stainless steel welders. The combination of the carcinogenic effects of asbestos exposure and smoking may account for part of the lung cancer excess observed.Key terms meta-analysis, stainless steel, welding.The risk of lung cancer in welders is an important issue in occupational epidemiology since (i) there may be as many as 3 million workers engaged in welding in industrialized countries (1) and (ii) welders may have been exposed to carcinogens according to welding activities, in particular exposure to hexavalent chromium and nickel when stainless steel is welded (1, 2). In addition, asbestos exposure is likely to have occurred in shipyards (2) and in other factories where welding is done (3).Following the multicentric European study, carried out by the International Agency for Research on Cancer (IARC), on the lung cancer risk of stainless steel welders as compared with that of mild steel welders (I), the question of whether stainless steel welders are at higher lung cancer risk than mild steel welders has been recently debated in the literature. The reviews by LangLd (4, 5) and the meta-analysis of 5 epidemiologic studies by Sjogren (6) suggested a specific relationship between lung cancer and exposure to hexavalent chromium and nickel when stainless steel is welded. Other authors have, however, disagreed with this proposal (7,...

Risk of lung cancer according to mild steel and stainless steel welding

“…This finding is consistent with that of a Swedish study that indicated that welders exposed to high levels of chromium have a higher risk for cancer of the trachea, bronchus, and lung than welders exposed to low levels of chromium (2, 3) and those of several other studies (26). Furthermore, the finding is biologically highly plausible (25), and the association did not disappear when smoking and asbestos exposure was adjusted for in the survival analysis (6,18,22). To test the hypothesis of higher risk for stainless steel welders, it seemed the most sensible to compare all welders that had been welding with stainless steel alloys, with only mild steel welders, even though many stainless steel welders were also mild steel welders.…”

“…The increased risk of lung cancer among mild steel welders is consistent with those found in a large number of earlier studies summarized in meta-analyses with updates (4,18,22). Earlier studies have found no clear indications that the risk is related to various measures of welding exposure (18).…”

“…However, it is still considered uncertain whether the increased risk of lung cancer in welders is explained by welding fumes in general, is caused by specific welding processes such as stainless steel welding, or is the result of confounding by tobacco smoking or asbestos exposure or other factors (6,14,22). With this background, we conducted this study to investigate whether the risk of lung cancer is related to the accumulated exposure to welding fume particulates among stainless steel and mild steel welders and to investigate whether associations, if any, remain when the effects of tobacco smoking and asbestos exposure are taken into account.…”

Immunotoxicology of arc welding fume: Worker and experimental animal studies

“…Multiple epidemiology studies have reported an elevated risk for the development of lung cancer among welders (Hansen et al, 1996;Moulin, 1997;Becker, 1999), whereas others have not (Steenland et al, 1991;Hansen et al, 1996;Danielsen et al, 2000). Moreover, epidemiological studies have been unable to correlate the development of lung cancer solely with exposure to Cr-containing SS welding fume as compared to non-Cr-containing MS fume (Moulin et al, 1993;Langard, 1994;Moulin, 1997). However, in vitro genotoxicity studies demonstrated that Cr-containing SS, but not MS, welding fumes are mutagenic and induce DNA damage (Hedenstedt et al, 1977;Maxild et al, 1978).…”

Welding Fume Exposure and Associated Inflammatory and Hyperplastic Changes in the Lungs of Tumor Susceptible A/J Mice

“…The International Agency for Research on Cancer (IARC) has concluded that WFs were "possibly carcinogenic" to humans, despite the fact that the finding was based on limited evidence in humans and inadequate evidence in laboratory animals (IARC, 1990). Several epidemiology studies suggest exposure to WFs is associated with an increased incidence of lung cancer (Becker, 1999;Moulin 1997;Simonato et al, 1991). However, other studies have not observed this elevated risk Address correspondence to: James M. Antonini, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, 1095 Willowdale Road (M/S 2015) Morgantown, WV 26505, USA; e-mail: jga6@cdc.gov * Denotes equal contribution to this work.…”