Cancer occurrence among European mercury miners

Objectives: To study the carcinogenicity of inorganic mercury in humans.Methods: We studied the mortality from cancer among 6784 male and 265 female workers of four mercury mines and mills in Spain, Slovenia, Italy and the Ukraine. Workers were employed between the beginning of the century and 1990; the follow-up period lasted from the 1950s to the 1990s. We compared the mortality of the workers with national reference rates.Results: Among men, there was no overall excess cancer mortality; an increase was observed in mortality from lung cancer (standardized mortality ratio [SMR] 1.19, 95 percent confidence interval [CI] 1.03-1.38) and liver cancer (SMR 1.64, CI 1.18-2.22). The increase in lung cancer risk was restricted to workers from Slovenia and the Ukraine: no relationship was found with duration of employment or estimated mercury exposure. The increase in liver cancer risk was present both among miners and millers and was stronger in workers from Italy and Slovenia: there was a trend with estimated cumulative exposure but not with duration of employment, and the excess was not present in a parallel analysis of cancer incidence among workers from Slovenia. No increase was observed for other types of cancer, including brain and kidney tumours. Among female workers (Ukraine only), three deaths occurred from ovarian cancer, likely representing an excess.Conclusions: Exposure to inorganic mercury in mines and mills does not seem strongly associated with cancer risk, with the possible exception of liver cancer; the increase in lung cancer may be explained by co-exposure to crystalline silica and radon.     

Lung cancer mortality among pottery workers in the United States

A proportionate mortality study suggested that members of the International Brotherhood of Potters and Allied Workers in the United States had an elevated frequency of deaths from non-malignant respiratory disease (PMR = 1.54) and lung cancer (PMR = 1.21). The lung cancer excess occurred exclusively among pottery workers employed in the manufacture of plumbing fixtures (PMR = 1.80). A subsequent cohort study examined mortality among 2055 white men employed in three ceramic plumbing fixture factories. There was a significant excess of non-malignant respiratory disease (SMR = 1.73). Lung cancer mortality was also higher than expected (SMR = 1.43) and was highest among workers whose jobs involved simultaneous exposure to silica and non-fibrous talc (SMR = 2.54). Lung cancer mortality risk increased with increasing number of years of exposure to non-fibrous talc and showed no pattern by number of years of exposure to silica. Among men exposed to talc, lung cancer risk increased with years since first non-fibrous talc exposure and decreased with age at first exposure. The data suggested an association between exposure to non-fibrous talc and excess lung cancer risk; however, the role of silica as a co-factor or promoting agent could not be ruled out.     

A quantitative assessment of lung cancer risk and occupational cadmium exposure.

We have performed a quantitative assessment of the risk of lung cancer from exposure to cadmium based on a retrospective cohort mortality study of cadmium-exposed workers. The findings were analysed using a life-table analysis to estimate standardized mortality ratios (SMRs), and various functional forms of Poisson and Cox proportionate hazards models to examine dose-response relationships. An excess mortality from lung cancer was observed for the entire cohort (SMR = 149,95% CI = 95-222). Lung cancer mortality was significantly elevated among non-hispanic workers, among those in the highest cadmium-exposure group, and among workers with 20 or more years since first exposure. A statistically significant dose-response relationship was evident in nearly all of the regression analyses. Based on our analyses, the lifetime excess lung cancer risk at the current OSHA standard for cadmium fumes of 100 micrograms/m3 is approximately 50-111 lung cancer deaths per 1000 workers exposed to cadmium for 45 years.     

Mortality from lung cancer and cardiovascular diseases among stainless-steel producing workers

The mortality pattern of workers involved in the production of stainless steel (SS) was studied from 1968 to 1984 in order to investigate a possible risk of lung cancer in relation to exposure to chromium compounds, polycyclic aromatic hydrocarbons, and silica. The role of heat exposure in mortality from cardiovascular diseases also was examined. The cohort was comprised of 4,227 workers. Complete individual job histories were provided by the company (UGINE SA). The smoking habits of 24 percent of the cohort members were known from the interview of workers still active during the data collection. The observed numbers of deaths were compared with the expected ones based on national rates with adjustment for age, sex, and calendar time (standardized mortality ratio, SMR). No significant excesses of lung cancer were observed among workers employed in the manufacture of ferroalloys (SMR=0.68) and in the melting and casting of SS (SMR=1.04), whereas a significant excess appeared among SS foundry workers (SMR=2.29). This excess was higher and remained significant among workers with more than 30 years since first employment in the foundry area (SMR=3.34). Among subjects exposed to heat, no excess was observed for all cardiovascular diseases or for ischemic heart diseases.Drs Moulin, Mur, and Wild and Ms Fournier-Betz are with the Institut National de Recherche et de Sécurité, Vandoeuvre, France. Drs Mantout and Smagghe are with the company UGINE SA, Paris la Défense, France. Address correspondence to Dr Moulin, INRS, Service Epidémiologie, BP 27, 54501 Vandoeuvre cédex, France.     

Lung cancer mortality in workers exposed to sulfuric acid mist and other acid mists

Mortality patterns were studied in 1,165 workers exposed to sulfuric acid mist and other acid mists (primarily hydrochloric acid mist) in steel-pickling operations. Standardized mortality ratio (SMR) analysis of the full "any acid exposure" cohort (n = 1,165), with the use of U.S. death rates as a standard, showed that lung cancer was significantly elevated, with a mortality ratio of 1.64 [95% confidence interval (CI) = 1.14-2.28, based on 35 observed deaths]. The lung cancer mortality ratio for workers exposed only to sulfuric acid (n = 722) was lower (SMR = 1.39), but further restriction to the time 20 years and more from first employment in a job with probable daily sulfuric acid exposure (approximately equal to 0.2 mg/m3) yielded a mortality ratio of 1.93 (95% CI = 1.10-3.13). An excess lung cancer risk was also seen in workers exposed to acids other than sulfuric acid (SMR = 2.24; 95% CI = 1.02-2.46). When comparison was made to other steel workers (rather than to the U.S. general population) to control for socioeconomic and life-style factors such as smoking, the largest lung cancer excess was again seen in workers exposed to acids other than sulfuric acid (SMR = 2.00; 95% CI = 1.06-3.78). Adjustment for potential differences in smoking habits showed that increased smoking was unlikely to have entirely explained the increased risk. Mortality from causes of death other than lung cancer was unremarkable, with the exception of significantly low rates for deaths due to digestive system diseases.     

Occupational exposure to vinyl chloride and cancer risk: a review of the epidemiologic literature.

Occupational exposure to vinyl chloride (VC) is causally related to liver angiosarcoma, whereas there is inconsistent epidemiologic evidence for other neoplasms. Two pooled analyses of worker cohorts from 56 plants in North America and Europe provide the most comprehensive and updated data on cancer risk among workers exposed to VC. These included over 22,000 workers, with a total of 640,000 person-years of observation, followed-up for up to 50 years. Overall, a total of 1,778 cancer deaths were observed versus 1,829.46 expected, corresponding to a standardized mortality ratio (SMR) of 0.97 (95% confidence interval (CI)=0.93-1.02). Excluding 71 confirmed angiosarcomas, there were 60 deaths from liver cancers versus 44.35 expected (SMR=1.35, 95% CI=1.03-1.74). Lung and laryngeal cancer mortality were significantly lower than expected (SMR=0.88 and 0.59, respectively). The SMRs for soft tissue sarcoma, brain, lymphoid and haematopoietic system cancers were not materially different from unity. Thus, the aggregate data from over 20,000 VC workers in North America and Europe exclude any excess mortality from lung, laryngeal, soft tissue sarcoma, brain, lymphoid and haematopoietic neoplasms. There appears to be a slight excess of liver cancer other than angiosarcoma, which is difficult to interpret and is likely due to residual misclassification of angiosarcomas.     

Mortality among industrial workers exposed to formaldehyde

A historical cohort study evaluated the mortality experience of 26,561 workers employed in 10 formaldehyde-producing or -using facilities. Approximately 600,000 person-years of follow-up accrued as workers were followed to January 1, 1980. Estimates of historical exposure to formaldehyde by job were developed by project industrial hygienists using monitoring data available from participating plants, comments from long-term workers, and comprehensive monitoring data specifically collected for this study. Mortality from all causes combined was about as expected [standardized mortality ratio (SMR) = 96] based on mortality rates of the general U.S. population. Significantly fewer deaths occurred from infective and parasitic diseases (SMR = 51) and from accidents (SMR = 72) than expected. Cancer overall was not related to formaldehyde exposure. Workers exposed to formaldehyde had slight excesses for Hodgkin's disease and cancers of the lung and prostate gland, but these excesses were not consistently related to duration of or average, cumulative, or peak formaldehyde exposure levels. Recent animal studies found nasal cancer among rats exposed to formaldehyde, but no excess of this tumor occurred in this study. Mortality from brain cancer and leukemia among these industrial workers was not excessive in contrast to reported excesses among professional groups (e.g., anatomists, embalmers, and pathologists) with exposure to formaldehyde. Although there was a deficit for cancer of the buccal cavity and pharynx, mortality from certain subsites, i.e., the nasopharynx and oropharynx, was elevated. These subsites did not, however, show a consistently rising risk with level of exposure. These data provide little evidence that mortality from cancer is associated with formaldehyde exposure at levels experienced by workers in this study.     

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.     

Occupational exposure to polychlorinated biphenyls and cancer risk.

Polychlorinated biphenyls (PCBs) are a class of chemicals characterized by a long-term persistence and diffusion in the environment, and by bioaccumulation through the food chain. The highest exposures occurred in occupational cohorts through inhalation or skin absorption in work environments. These cohorts can therefore provide important information on health risk from exposure to PCBs in the general population. To provide comprehensive evidence on cancer risk from PCB exposure, we have thus reviewed the epidemiological studies on workers occupationally exposed to PCBs. Overall, no excess for all cancer mortality was observed in the six studies providing information (573 cancer deaths versus 630.4 expected, corresponding to a standardized mortality ratio (SMR) of 91). Among neoplasms potentially related to PCB exposure, there were 12 deaths from liver cancer compared with 9.5 expected (SMR=126). No excess was found for cancers of the breast (40 observed versus 47.4 expected, SMR=84) and of the lymphatic and haematopoietic system (51 observed versus 53.2 expected, SMR=96). Therefore, studies on occupational exposure to PCBs do not show any excess in all cancer mortality, or in mortality for specific cancer sites of interest.     

Lung cancer incidence among patients with beryllium disease: a cohort mortality study

We have conducted a cohort mortality study on 689 patients with beryllium disease who were included in a case registry. An earlier mortality study on 421 of these patients was limited to males and resulted in a determination of a nonsignificant twofold lung cancer excess based on only seven lung cancer deaths. We have extended this earlier study by including females and by adding 13 years of follow-up. Comparison of the 689 beryllium disease patients with the U.S. population resulted in a lung cancer standardized mortality ratio (SMR) of 2.00 (95% confidence interval = 1.33-2.89) based on 28 observed lung cancer deaths. Adjustment for smoking did not change these results. All causes of mortality were also significantly elevated (SMR = 2.19), largely because of the very high rate of deaths due to pneumoconioses (primarily beryllium disease) (SMR = 34.23; 158 deaths). No other causes of death were significantly elevated. The excess of lung cancer was consistent for both sexes and did not appear to increase with duration of exposure to beryllium or with time elapsed since first exposure to this element. The case registry included those with acute beryllium disease, which resembles a chemical pneumonitis, and those with chronic beryllium disease, which resembles other pneumoconioses. The lung cancer excess was more pronounced among those with acute disease (SMR = 2.32) than among those with chronic disease (SMR = 1.57).     

Occupational lung cancer among copper smelters

Because a remarkably high lung cancer mortality rate was noted among males in a certain town, a case control study was carried out on the basis of mortality cards. The case group consisted of 19 males who died from lung cancer and the control group included 19 males who had died from diseases other than cancer of the lung, urinary bladder, and skin. The only significant difference between the groups was that 11 of the 19 who had died from lung cancer had been employed as smelters in a local copper refinery. Prolonged exposure to arsenic, and possibly also other compounds, seemed to be associated with cancer of the lung. The validity of the diagnosis of these lung cancer cases was also checked by blind examination of chest X-ray films of the patients with occupational cancer, a group of other lung cancer patients, and the controls. The occupational cancer was diagnosed at a higher rate than the tumors of other lung cancer cases. In all the 11 cases, the disease had become manifest after the men had stopped working at the refinery. None of them had been considered as having occupational cancer by the physicians who treated them, their previous employer, the authorities concerned, their family and friends, or indeed themselves, until this study was conducted. The necessity of a lifelong health care system for ex-smelters from copper refineries was emphasized.     

Further evidence for a link between silica dust and esophageal cancer

Our objective was to examine the relationship between silicosis and esophageal cancer in Hong Kong. The mortality of esophageal cancer was investigated among caisson and non-caisson workers in a cohort of 2,789 male silicotic workers in Hong Kong during the period 1981-99. The standardized mortality ratio (SMR) was calculated using the Hong Kong general population rates as reference. The indirect method proposed by Axelson was used to adjust for the confounding effects of cigarette smoking and alcohol drinking. The SMR of esophageal cancer in the entire cohort was 2.22 (95% CI 1.36-3.43, based on 20 deaths) and was 4.21 (95% CI 1.81-8.30, based on 8 deaths) in the subgroup of caisson workers who had a higher exposure to silica dust. The relative risk of esophageal cancer for caisson silicotics was reduced to 2.34 after adjusting for the effects of smoking and alcohol drinking. No more excess risk of esophageal cancer was observed among non-caisson silicotic workers after the adjustments. This historical cohort study revealed that there was an increased mortality risk of esophageal cancer among silicotics who had worked in underground caissons in Hong Kong after adjusting for cigarette smoking and alcohol drinking. We believe that the excess risk of esophageal cancer mortality among caisson workers with silicosis could best be explained by the very heavy exposure to free silica dust in their working environment.     

Mortality among a cohort of U.S. cadmium production workers--an update

A previous retrospective mortality study of 292 U.S. cadmium production workers employed for a minimum of 2 years showed increased mortality from respiratory and prostate cancer and from nonmalignant lung disease. To examine further the mortality experience of these workers, investigators from the National Institute for Occupational Safety and Health extended the study to include 602 white males with at least 6 months of production work in the same plant between 1940 and 1969. Vital status was determined through 1978, which included the addition of 5 years to the original follow-up. Cause-specific mortality rates for seven causes of death potentially related to cadmium exposure were compared between the overall cohort and U.S. white males and between subgroups. Mortality from respiratory cancer and from nonmalignant gastrointestinal disease was significantly greater among the cadmium workers than would have been expected from U.S. rates. All deaths from lung cancer occurred among workers employed for 2 or more years. A statistically significant dose-response relationship was observed between lung cancer mortality and cumulative exposure to cadmium. A 50% increase in lung cancer mortality, which was not statistically significant, was observed even among workers whose cumulative exposure to cadmium was between 41 and 200 micrograms/m3 over 40 years. Since the previous investigation, no new deaths from prostate cancer and no excess of deaths from nonmalignant respiratory disease have been observed.     

A cohort study of cancer mortality among Biology Research Laboratory workers in The Netherlands

OBJECTIVE: To examine cancer mortality among persons employed in biology research institutes. METHOD: A historical cohort study was undertaken in the Netherlands. The cohort, comprising 7307 laboratory workers employed by the four participating institutes between 1960 and 1992, was followed for mortality from 1960 to 1995 (median follow-up time 16.5 years). Causes of death were obtained for 98% of all deaths. Cancer mortality in the cohort was compared with that in the general population by computation of the standardized mortality ratio (SMR). The Cox proportional hazards model was used to compare cancer mortality among laboratory workers with that in an internal reference population consisting of unexposed research personnel (n = 2,404). RESULTS: All-cause mortality among laboratory workers was significantly lower than that in the general population. Total cancer mortality and lung cancer mortality were also significantly decreased (SMR = 0.8; 95% confidence interval CI = 0.7-0.9 and SMR = 0.7; 95% CI = 0.6-0.9), respectively. However, when compared to the internal reference population, laboratory workers had a slightly increased cancer mortality (relative risk (RR) = 1.3 95% CI = 0.9-1.9). Among men, a 2.5-fold (95% CI = 1.0-6.3) increase of lung cancer mortality was observed which could not be explained by differences in smoking habits. Lung cancer mortality increased with longer follow-up. Results with regard to a priori defined fields of research showed significantly increased cancer mortality (in particular from lung cancer) for men working in genetics (RR = 3.8), virology (RR = 4.1) and plant physiology (RR = 2.1). CONCLUSION: Laboratory workers have a favorable cancer mortality pattern as compared to the general population. However, this favorable pattern disappears when a comparison is made with a control group of unexposed research personnel. The excess lung cancer mortality among male laboratory workers was concentrated in certain fields of research, which warrants further research to identify specific exposures related to the increased risk.     

Cancer mortality in relation to monitoring for radionuclide exposure in three UK nuclear industry workforces.

Cancer mortality in 40,761 employees of three UK nuclear industry facilities who had been monitored for external radiation exposure was examined according to whether they had also been monitored for possible internal exposure to tritium, plutonium or other radionuclides (uranium, polonium, actinium or other unspecified). Death rates from cancer were compared both with national rates and with rates in radiation workers not monitored for exposure to any radionuclides. Among workers monitored for tritium exposure, overall cancer mortality was significantly below national rates [standardized mortality ratio (SMR) = 83, 165 deaths; 2P = 0.02] and none of the cancer-specific death rates was significantly above either the national average or rates in non-monitored workers. Although the overall death rate from cancer in workers monitored for plutonium exposure was also significantly low relative to national rates (SMR = 89, 581 deaths; 2P = 0.005), mortality from pleural cancer was significantly raised (SMR = 357, nine deaths; 2P = 0.002); none of the rates differed significantly from those of non-monitored workers. Workers monitored for radionuclides other than tritium or plutonium also had a death rate from all cancers combined that was below the national average (SMR = 86, 418 deaths; 2P = 0.002) but prostatic cancer mortality was raised both in relation to death rates in the general population (SMR = 153, 37 deaths; 2P = 0.02) and to death rates in radiation workers who had not been monitored for exposure to any radionuclide [rate ratio (RR) = 1.65; 2P = 0.03]. Mortality from cancer of the lung was also significantly increased in workers monitored for other radionuclides compared with those of radiation workers not monitored for exposure to radionuclides (RR = 1.31, 164 deaths; 2P = 0.01). For cancers of the lung, prostate and all cancers combined, death rates in monitored workers were examined according to the timing and duration of monitoring for radionuclide exposure, with rates of radiation workers not monitored for any radionuclide forming the comparison group. In tritium-monitored workers, RRs for prostatic cancer varied significantly according to the number of years in which they were monitored (2P = 0.03). In workers monitored for plutonium exposure, RRs for all cancers combined increased with the number of years in which they were monitored (2P = 0.04) and with the number of years since first monitoring (2P = 0.0003). There was little suggestion of systematic variation in RRs for workers monitored for other radionuclides in relation to the timing or duration of monitoring, nor did it appear that their raised rates of cancer of the lung and prostate were explained by external radiation dose. These analyses of cancer mortality in relation to monitoring for radionuclide exposure reported in a large cohort of nuclear industry workers suggest that certain patterns of monitoring for some radionuclides may be associated with higher death rates from cancers of the lung, pleura, prostate and all cancers combined. Some of these findings may be due to chance. Moreover, because of the paucity of related data and lack of information about other possible exposures, such as whether plutonium workers are more likely to be exposed to asbestos, firm conclusions cannot be drawn at this stage. Further investigations of the relationship between radionuclide exposure and cancer in nuclear industry workers are needed.     

Long-term mortality study of oil refinery workers. IV. Exposure to the lubricating-dewaxing process

A retrospective cohort mortality study of 1,008 male oil refinery workers who ever worked on the lubricating-dewaxing process of the lube oil department and who have been followed for a period of 43 years is presented. These workers were exposed to a number of solvents, primarily methyl ethyl ketone [(MEK) CAS: 78-93-3] and toluene (CAS: 108-88-3), but at levels far below the current Occupational Safety and Health Administration's standard. The standardized mortality ratio (SMR) for all causes (0.70) and the SMR for cancer (0.86) are much lower than unity when they are compared to the mortality experience of the U.S. population. Also observed in this study were 8 prostate cancer deaths (4.4 expected) with an SMR of 1.82, which was not statistically significant (P = .16). Seven of these 8 prostate cancer deaths occurred among nonwhite males, who showed an SMR of 2.47 (P = 0.53). However, only 1 prostate cancer death was seen among workers specifically assigned to the MEK units. The remaining deaths occurred among maintenance workers who had lube oil department-wide assignments. This cancer risk increased with increasing duration of employment in the lube oil department. A latency of 20 years or more was also observed for these prostate cancer deaths. In this study the processing of lubricating oils was found to be at least as important as the MEK solvents, and department-wide maintenance workers were as much at risk as the MEK unit workers. In view of this finding and findings obtained by others, it seems prudent to continue to study lubricating-dewaxing process workers, including the medical monitoring of all such workers for prostate cancer.     

Mortality patterns among nickel/chromium alloy foundry workers

All deaths between 1968 and 1979 from 26 foundries were studied to determine whether exposure to nickel/chromium resulted in an increased rate of any cause-specific mortality. The mortality experience of 851 foundrymen exposed to nickel/chromium was compared to that of 141 unexposed foundrymen. No nasal cancers were found. The exposed subgroup had a slightly lower proportion of cancer deaths, including lung cancer, and a slightly higher rate of nonmalignant respiratory disease deaths compared with the unexposed subgroup. Length of exposure was not significantly related to any of the selected cause-specific proportional mortality rates after adjusting for age, length of employment, and race. Standardized comparisons with the 1974 United States mortality patterns indicated that the total numbers of lung cancer and all cancer deaths were not significantly different from expected values for these exposed foundrymen, although there was an excess of lung cancer deaths among white males aged 65-99. These lung cancer rates followed an increasing trend with increasing length of foundry employment, although the trend was not statistically significant. However, this pattern does suggest that the excess of lung cancer deaths may be associated with length of foundry employment rather than exposure to nickel/chromium. There was a significant excess of respiratory system disease deaths among exposed workers associated with length of foundry employment, regardless of exposure to nickel/chromium. When all malignant and nonmalignant respiratory disease deaths are combined, there is no evidence of an increased risk associated with exposure to nickel/chromium.     

Population‐based cohort study on health effects of asbestos exposure in Japan

Occupational asbestos exposure occurs in many workplaces and is a well‐known cause of mesothelioma and lung cancer. However, the association between nonoccupational asbestos exposure and those diseases is not clearly described. The aim of this study was to investigate cause‐specific mortality among the residents of Amagasaki, a city in Japan with many asbestos factories, and evaluate the potential excess mortality due to established and suspected asbestos‐related diseases. The study population consisted of 143 929 residents in Amagasaki City before 1975 until 2002, aged 40 years or older on January 1, 2002. Follow‐up was carried out from 2002 to 2015. Standardized mortality ratio (SMR) with its 95% confidence interval (CI) was calculated by sex, using the mortality rate of the Japanese population as reference. A total of 38 546 deaths (including 303 from mesothelioma and 2683 from lung cancer) were observed. The SMRs in the long‐term residents’ cohort were as follows: death due to all causes, 1.12 (95% CI, 1.10‐1.13) in men and 1.07 (95% CI, 1.06‐1.09) in women; lung cancer, 1.28 (95% CI, 1.23‐1.34) in men and 1.23 (95% CI, 1.14‐1.32) in women; and mesothelioma, 6.75 (95% CI, 5.83‐7.78) in men and 14.99 (95% CI, 12.34‐18.06) in women. These SMRs were significantly higher than expected. The increased SMR of mesothelioma suggests the impact of occupational asbestos exposure among men and nonoccupational asbestos exposure among women in the long‐term residents’ cohort. In addition, the high level of excess mortality from mesothelioma has persisted, despite the mixture of crocidolite and chrysotile no longer being used for three or four decades.     

Mortality from respiratory and digestive cancers among asbestos cement workers in Italy.

A cohort study is presented on the mortality of blue-collar workers in an asbestos-cement production plant that has been operating since 1907. Use of both crocidolite and chrysotile is reported. The cohort includes 2608 men and 759 women who were employed in the plant on Jan. 1, 1950 and those who started to work between 1950 and 1980. Follow-up was terminated on April 15, 1986 with 97.9% traced. Expected deaths were estimated from the age- and sex-specific regional mortality rates for the years 1969 to 1981. The data have been analyzed for the period 1964 to 1986 based on person-years at risk: 43,000 for men and 14,494 for women. A statistically significant increase was found in both sexes for mortality from all causes. From 1964 to 1986, 728 men died from all causes (608 expected), 275 with cancer at any site (158 expected) 110 with lung cancer (41 expected), 28 with pleural tumors (1 expected) and 85 with asbestosis (less than 1 expected). Corresponding figures for women were--all causes: 136 deaths versus 102 expected; all cancers: 79 verses 32 expected; lung cancer: 7 versus 2 expected; pleural tumor: 15 versus 0 expected and asbestosis: 4 versus 0 expected. Deaths from digestive tract cancer were in excess only among women (18 observed versus 10 expected, p less than 0.01). No excess was found for deaths from laryngeal cancer. Standardized mortality rates (SMR) for lung cancer among males showed a clear increase in direct relationship with length of follow-up. SMR according to length of employment were 234 for length 10 to 19 years, 363 for 20 to 29 years, and 256 for 30 years or longer (p less than 0.05 and lower).     

Cancer risk in carbon electrode workers: an overview of epidemiological evidence.

Carbon or graphite electrode manufacturing may lead to exposure to polycyclic aromatic hydrocarbons, some of which are considered human carcinogens. To provide comprehensive evidence on cancer risk, we have considered five cohort studies from the USA, France, Sweden and Italy, including about 6,500 workers and 80,000 man-years at risk. In two studies providing data on incidence, 52 incident cases of all neoplasms were reported versus 56.28 expected, corresponding to a standardized incidence ratio (SIR) of 0.92. There were nine cases of lung cancer (SIR=0.91) and three of urinary cancers (SIR=0.81). Four studies gave data on mortality. Overall, 853 deaths were observed versus 1,065.2 expected, corresponding to a standardized mortality ratio (SMR) of 0.80 (95% confidence interval, CI, 0.75-0.86). There were 269 deaths from all neoplasms, versus 292.1 expected (SMR=0.92, 95% CI 0.81-1.04), 82 deaths from respiratory cancers versus 95.8 expected (SMR=0.86), and 15 deaths from bladder and urinary cancers versus 12.7 expected (SMR=1.18). None of these estimates were significant, and for none of the other cancer sites there was evidence of excess risk. Thus, epidemiological data allow excluding any appreciable risk of cancer--in particular of the respiratory and the urinary tract--in carbon electrode workers.