Biomedical subjects
L Simonato
Publications and source records attributed to L Simonato.
A historical prospective study of European stainless steel, mild steel, and shipyard welders.
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.
A collaborative study of cancer incidence and mortality among vinyl chloride workers.
A large European multicentric cohort study has been coordinated by the International Agency for Research on Cancer with the objectives of investigating the dose-response relationship between liver cancer and exposure to vinyl chloride and assessing cancer risk for sites other than the liver. A nearly threefold increase in liver cancer was detected on the basis of 24 observed deaths and 8.4 expected (standardized mortality ratio 286, 95% confidence interval 186-425). The excess from liver cancer was clearly related to time since first exposure, duration of employment, and estimated ranked and quantitative exposures. Other cancer sites investigated on the basis of a priori hypotheses were either not in excess (lung) or apparently unrelated to the exposure variables (brain and lymphoma).
Epidemiological aspects of the relationship between exposure to silica dust and lung cancer.
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A mortality study of a cohort of slate quarry workers in the German Democratic Republic.
Following reports from other countries indicating an excess risk of lung cancer among silicotics, a historical cohort of workers employed for at least one year at a company in charge of slate extraction and processing during the period 1953-1985 in the German Democratic Republic has been constructed and followed up for mortality from 1970 to 1985. The results of the study show a mortality excess for infectious and respiratory diseases. The overall lung cancer mortality is not in excess but shows a tendency to increase with time since first exposure. A mortality excess from lung cancer is concentrated among workers receiving compensation for silicosis, suggesting a possible carcinogenic risk for individuals suffering from this pathological condition.
Definition of exposure in epidemiological studies on foundry workers.
Epidemiological analytical studies investigating lung cancer risk among foundry workers are reviewed in relation to the available information on exposure. Nine studies (eight historical cohorts and one case-control) have been included. Overall, the information on exposure was poor. In none of the studies were there industrial hygiene measurements for investigating dose-response relationships, while duration of employment was the most common proxy of exposure utilized. None of the studies made an attempt to construct job-exposure matrices. The interpretation of the evidence in causal terms appears mainly based on the consistency across studies of the increased lung cancer mortality rather than on the relationship between the exposure in the working environment and the excess mortality reported.
Aplastic anemia, leukemia and other cancer mortality in a cohort of shoe workers exposed to benzene.
Benzene is a well documented carcinogen for the hematic and lymphopoietic system, and experimental research confirms its carcinogenicity for tumors of other sites. This report presents the results of a historical cohort study in a shoe manufacturing plant in Florence where cases of aplastic anemia and leukemia were reported in the 1960s. A total of 1008 men and 1005 women were considered eligible members of the cohort. For total mortality, comparing the rates of the cohort with the national rates, the standardized mortality ratio (SMR) was 79 for the women and 95 for the men. For the men excesses of risk for aplastic anemia [SMR 1566; 95% confidence interval (95% CI) 547-3264] and leukemia (SMR 400, 95% CI 146-870) were observed. The increased risk occurred among workers first employed during the period in which benzene was used, but the expected number of cases in the subsequent period was too small to evaluate whether any reduction in risk had occurred. No increasing pattern with duration of employment was discernible.
Relation of environmental exposure to erionite fibres to risk of respiratory cancer.
During the period 1979-1983, IARC, in collaboration with the Department of Chest Diseases of Hacettepe University in Ankara and the MRC Pneumoconiosis Unit in Penarth, conducted an epidemiological and environmental survey in 4 villages in central Turkey affected by a high incidence of mesothelial tumours. Recent data point to erionite, a zeolite fibre, as the most plausible etiological agent. From animal experiments, erionite appears to be the most powerful carcinogenic fibre so far known. During the study period, 17 pleural mesotheliomas and 7 lung cancer cases have been reported among the villagers. These cancer cases are analysed in relation to exposure to fibres. We assume exposure to occur from birth onwards and therefore consider duration of exposure equal to age. On this basis, the incidence of mesothelial and lung tumours is analysed in relation to age and cumulative exposure to fibres computed using the airborne fibre levels measured during the survey.
Mesothelioma in Cyprus.
For many years, the main source of asbestos in Cyprus was thought to be the chrysotile mine in the central mountains. When a woman, who had no connection with the mine, developed mesothelioma, it was surprising to discover tremolite asbestos bodies within her lung. However, further studies have shown that tremolite occurs as a contaminant within the chrysotile ore body. In this study we have shown that both chrysotile and tremolite can be found in domestic and environmental samples throughout the mountain region; in particular, numerous fine fibres of both materials are present in stucco. Preliminary radiological studies have shown pleural disease in the village population and 5 out of 13 known cases of mesothelioma have arisen in persons unconnected with the mine. This suggests an environmental contribution to asbestos-related disease on the island.
A case-referent study investigating the relationship between exposure to silica dust and lung cancer.
A case-referent study was carried out to investigate the relationship between lung cancer and exposure to silica dust in an area where a relatively high proportion of the workforce was exposed to silica dust in the past. The cases were 309 lung cancer patients admitted at the Chest Department of the Central Belluno Hospital during the period 1973-1980, while the 309 controls were patients admitted at the same department for diseases other than lung cancer and bronchitis during the same period. Information on exposure to silica and smoking habits were collected from hospital records. The results show an elevated risk, supported by a clear dose-response, due to smoking. Exposure to silica also appears to increase the risk of lung cancer, but only in presence of silicosis. The risk estimates tend to increase both with amount of smoking and duration of exposure to silica, with the magnitude of the risk being, however, much smaller for the latter effect. No clear interaction appears to exist between the two factors. The limitations of the study and the problems in interpreting the results are discussed.
Estimates of the proportion of lung cancer attributable to occupational exposure.
The proportion of lung cancer due to occupational exposure has been estimated by computing the attributable risk in the population (ARp) from various case-control studies. Different criteria have been used in including occupational exposures from published studies: (i) exposure to lung carcinogens according to a job-exposure matrix approach; (ii) occupations in which an increased risk of lung cancer has been established; (iii) occupations in which an increased risk of lung cancer has been suggested; and (iv) occupations associated with a statistically significant increase of lung cancer. Only studies in which the confounding effect of smoking was controlled for have been included. We found a wide variability of ARp estimates, mainly due to the different geographical locations of the studies, while they seem to be only moderately affected by the different criteria of inclusion of the relevant occupational exposures. Studies using job-exposure matrices gave ARps ranging from 0.6% to 35%. When a list of recognized carcinogenic exposures was used for the selection of the relevant occupations, the estimates varied between 2.4% and 40%. From the studies reviewed it also appears that tobacco smoking has a very limited confounding effect. Various limitations of the exercise are discussed.
[The proportion of tumors of the lung caused by occupational exposure: updating].
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Epidemiological and environmental evidence of the health effects of exposure to erionite fibres: a four-year study in the Cappadocian region of Turkey.
An environmental and epidemiological study has been carried out in Central Cappadocia, Turkey, aiming at investigating the relationship between exposure to naturally occurring erionite fibres and the reported high incidence of malignant mesotheliomas. Airborne fibre levels are generally low but show a higher proportion of erionite fibres in the villages affected by malignant disease than in a control village. The same pattern is confirmed by analysis of the fibre content in lung tissues of sheep from several villages, both affected and unaffected by malignant disease. The 3 villages with the highest proportion of erionite fibres have high rates of malignant pleural mesothelioma, malignant peritoneal mesothelioma and lung cancer. No case of malignancy for the same sites has been reported during the study period from the control village. The relationships between these findings and their consistency with the results from experimental studies indicate erionite fibres as a carcinogenic agent, although some aspects of the exposure are not fully clarified.
The International Agency for Research on Cancer historical cohort study of MMMF production workers in seven European countries: extension of the follow-up.
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Mesothelioma in Cyprus: the role of tremolite.
There is a chrysotile mine in the central mountains of Cyprus but no other appreciable source of industrial asbestos. Hence the island was thought to offer ideal conditions to seek pure chrysotile induced mesothelioma. The first reported case was a village woman whose lung tissue contained amphibole asbestos fibres, which were later identified as tremolite. This began a search for the origin of her exposure to asbestos. Our studies have shown that tremolite is widespread, being found, along with chrysotile, in domestic and environmental dust samples. Other cases of mesothelioma have been diagnosed, and the pattern of their distribution suggests that the mine is not the major source of disease. Exposure to tremolite is equally, if not more, important.
Mortality of workers compensated for silicosis during the period 1959-1963 in the Veneto region of Italy.
After reports appeared from other countries indicating an excess risk of lung cancer among silicotics, a cohort of workers compensated for silicosis during the period 1959-1963 in the Veneto region of Italy was constructed and followed for mortality through 1984. The results of the study showed a large mortality excess for infectious diseases (180 observed versus 9.5 expected), due to silicotuberculosis, and for diseases of the respiratory system (270 observed versus 33.5 expected) due to silicosis. An elevated standardized mortality ratio of 239 (70 observed versus 29.3 expected) from lung cancer was also detected. An increasing pattern was observed with time since first exposure, while the relationship with employment category and duration of exposure was less clear-cut. The lung cancer excess was also strongly associated with cigarette smoking, there being a dose-response relationship with daily cigarette consumption. The study confirms the results from other epidemiologic studies on silicotics which show this pathological condition to be associated with increased lung cancer mortality.
Updating lung cancer mortality among a cohort of man-made mineral fibre production workers in seven European countries.
A historical cohort of 21,967 workers ever employed in 13 European factories manufacturing various types of man-made mineral fibres (MMMF) was observed until 1982. Overall there were 2719 deaths (standardised mortality ratio (SMR) = 111) of which 189 were from lung cancer (SMR = 125). For the glasswool and rockwool/slagwool production subcohorts the lung cancer SMRs rose with time since first exposure, exceeding 170 for the period of 30 or more years. Adjustment for regional variations in mortality substantially reduced the excess in the glasswool group, but not in the rockwool/slagwool. In neither subgroup was there any relationship of lung cancer mortality with length of employment. During the early years of rockwool/slagwool production there was the potential for much higher fibrous dust exposure than at present, because of the absence of dust suppressing oil and/or the use of a batch production process. In addition slag was widely used as a raw material. Amongst workers employed during the early phase, there were 10 lung cancer deaths giving SMRs of 270 and 244 for the periods 20-29 and 30 or more years since first exposure. This group accounts for most of the absolute excess of lung cancer for the rockwool/slagwool plants.