A multicentre cohort of 11 092 male welders from 135 companies located in nine European countries has been assembled with the aim of investigating the relation of potential cancer risk, lung cancer in particular, with occupational exposure. The observation period and the criteria for inclusion of welders varied from country to country. Follow up was successful for 96-9% of the cohort and observed numbers of deaths (and for some countries incident cancer cases) were compared with expected numbers calculated from national reference rates. Mortality and cancer incidence ratios were analysed by cause category, time since first exposure, duration of employment, and estimated cumulative dose to total fumes, chromium (Cr), Cr VI, and nickel (Ni). Overall a statistically significant excess was reported for mortality from lung cancer (116 observed v 86-81 expected deaths, SMR = 134). When analysed by type of welding an increasing pattern with time since first exposure was present for both mild steel and stainless steel welders, which was more noticeable for the subcohort of predominantly stainless steel welders. No clear relation was apparent between mortality from lung cancer and duration of exposure to or estimated cumulative dose of Ni or Cr. Whereas the patterns of lung cancer mortality in these results suggest that the risk of lung cancer is higher for stainless steel than mild steel welders the different level of risk for these two categories of welding exposure cannot be quantified with precision. The report of five deaths from pleural mesothelioma unrelated to the type of welding draws attention to the risk of exposure to asbestos in welding activities.The first study reporting an increased risk for lung cancer among welders was the case-control study by Breslow et al.' Since that time, several case-control studies of lung cancer have reported findings for welders,"' and a number of cohort studies of welders' mortality have been carried out."24 Most of these studies, along with several analyses of routine mortality data, have reported excesses of mortality from lung cancer ranging from 30% to 50%. Few studies, however, have investigated the potential carcinogenic effect of exposures to specific welding fumes.They have been reviewed by Peto" and by the International Agency for Research on Cancer (IARC).26 Welders are exposed to welding fume, which in the case of stainless steel welding contains the carcinogens nickel (Ni) and chromium (Cr). Also, some welders are at risk of exposure to asbestos (particularly in shipyards) and suspected carcinogens such as silica dust.27 Many earlier studies did not subdivide welders by type of exposure; therefore the major aim of this study has been the separation of stainless steel welders, potentially exposed to Cr and Ni, from mild steel welders and welders in shipyards. This historical prospective study is unable, as in most such studies, to measure the potential confounding effect of smoking habits.The IARC coorganised with the European Regional Offiice of the World Health Org...

Stainless steel welding is associated with exposure to metals including hexavalent chromium and nickel. This study is a meta-analysis of five studies of stainless steel welders and the occurrence of lung cancer. Asbestos exposure and smoking habits have been taken into account. The calculated pooled relative risk estimate was 1*94 with a 95% confidence interval of 1-2S-2-93. This result suggests a causal relation between exposure to stainless steel welding and lung cancer. The study showed an association between lung cancer and welders exposed to nickel. All the welders exposed to nickel who had lung cancer were also exposed to chromium. The odds ratio (OR) was 3-3 with the corresponding 95% confidence interval (95% CI) 1 2-9 2. Adjustments were made for age, ethnic group, social class, and smoking habits. Other possible confounders such as asbestos exposure were coded on an extensive checklist. Asbestos exposure was not sufficiently correlated with nickel exposure and with lung cancer to have artificially created such a large OR between nickel and lung cancer.4In a case-referent study nested in a cohort of Danish welders the OR for lung cancer associated with ever stainless steel welding was 1-57 (95% CI 0-85-2-89) after adjusting for smoking and asbestos exposure. Exposure to stainless steel welding fumes for at least two decades increased the OR to 1-93 (95% CI 0-74-5 06).5A cohort of 2721 French welders were compared with 6683. non-welding manual workers and with the-eneral French population. The mortality of the two cohorts was studied from 1975 to 1988. Smoking was more prevalent among the welders and this was assumed to lead to a 6% excess of lung cancer v the non-welding referents. Asbestos exposure was probably higher in shipyards than in other factories and asbestos exposure was not assumed to be responsible for lung cancers among non-shipyard welders. The cohort of non-shipyard welders included a subcohort of welders exposed to stainless steel welding fumes. Welders were included in this subcohort if more than 70% of their welding activities, for at least one year, comprised manual metal arc welding of stainless steel or armoured steel with stainless steel coated electrodes or oxyacetylene welding or cutting of stainless steel. The number of lung cancers found within this subcohort of predominantly stainless steel welders was 2 v 1-95 expected (standardised mortality ratio (SMR = 1-03) from the general French population.6Assuming the smoking habits among the subcohort of the stainless steel welders to be the same as the main cohort of welders and the habits among the non-welding referents to be the same as the general French population, the calculated SMR would be 0-97. In a Norwegian case-referent study of lung cancer an increased OR was found for welders exposed to stainless steel welding fumes when smoking habits were taken into account, OR = 3-3 (95% CI 12-9-3). When both asbestos exposure and smoking were included in the logistic regression equation the association was weaker, OR = 2-56...

SUMMARYThe deleterious effects of aluminiutn in the rhizosphere on growth, root morphology, ion uptake, and stomatal conductance in wheat {Triticum aestivum L.) were prevented or attenuated hy the inclusion of fluoride in the growth medium; the more fluoride present relative to the concentration of aluminium, the greater the alleviation. Results support the conclusion that the ameliorative effects of fluoride were due to reductions in the concentration of the rhizotoxic trivalent cation (Al^^) through the formation of aluminium-fluoride complexes that are neither phytotoxic nor readily translocated from roots to shoots.

A survey of the literature shows that organic and inorganic compounds of 53 metals have been assayed for genotoxic effects in vitro and in vivo. It is falund that there are great variations in the response obtained with different test systems and that a wide range of compounds of the different metals is positive in at least one of the short-term tests. Some of the variation observed could be due to differences in uptake mechanisms. This effect plus the wide variation in the quantity and quality of the data ]prevents any direct comparison of in vitro activity with in vivo potency of the various imetallic species. Downloaded from Group 5. Mutation Tests Using E. coli E. coli is used for detection of mutagenic activity in the same way as S. fyphimurium. Different strains of E. coli detect forward as well as reversed mutations. Three essentially different test pro-Address reprint requests to:

An in vitro bioassay utilizing BHK-21 cells in culture is used to determine the relative transformation potential of a number of nickel compounds including, as relatively insoluble particulates a known carcinogen (Ni3S2) and several oxides either of commercial interest or found in the working environment in the metal industry (e.g., NiO), and a soluble salt [Ni(CH3COO)2]. Although a wide range of transformation potency is found as a function of the dose of Ni per area of culture, all substances produce the same number of transformed colonies at the same degree of toxicity (e.g., 50% survival). If toxicity is a direct measure of intracellular concentration, then apparently nickel per se is the ultimate transforming agent independent of source or uptake mechanism.