Mortality and lead exposure: a retrospective cohort study of Swedish smelter workers.

The study is based on the work histories and mortality data for 3832 male workers first employed before 1967 at a copper smelter in northern Sweden and followed up from 1950 to 1981. From the 3832 workers a lead cohort consisting of 437 workers employed for at least three years at sites with considerable lead exposure during 1950-74 was selected. These workers had regularly had blood lead measurements performed since 1950. Based on the cumulative blood lead dose 1950-74 and peak blood lead values, the cohort was subdivided into high mean, low mean, high peak, and low peak groups. Standardised mortality ratios (SMR) were calculated for the six groups using general and local reference populations. The original cohort of 3832 workers showed considerable excess of deaths for total mortality, malignant neoplasms especially lung and stomach cancer, ischaemic heart diseases, and cerebrovascular diseases when compared with the general population. In the lead cohort where the workers had been subjected to a considerable lead exposure only the raised SMR for lung cancer was sustained (SMR = 162; not significant). No significant differences were found between high lead and low lead exposed smelter workers.     

Mortality of lead smelter workers

To examine patterns of death in lead smelter workers, a retrospective analysis of mortality was conducted in a cohort of 1,987 males employed between 1940 and 1965 at a primary lead smelter in Idaho. Overall mortality was similar to that of the United States white male population (standardized mortality ratio (SMR) = 98). Excess mortality, however, was found from chronic renal disease (SMR = 192; confidence interval (CI) = 88-364), and the risk of death from renal disease increased with increasing duration of employment, such that after 20 years employment, the standardized mortality ratio reached 392 (CI = 107-1,004). Excess mortality was also noted for nonmalignant respiratory disease (SMR = 187, CI = 128-264). Eight of 32 deaths in this category were caused by silicosis; at least five workers who died of silicosis had been miners for a part of their lives. An additional 11 deaths resulted from tuberculosis (SMR = 139; CI = 69-249); in six of these cases, silicosis was a contributory cause of death. Cancer mortality was not increased overall (SMR = 95; CI = 78-114). An increase, however, was noted for deaths from kidney cancer (six cases; SMR = 204; CI = 75-444). Finally, excess mortality was noted for injuries (SMR = 138; CI = 104-179); 13 (23%) of the 56 deaths in this category were caused by mining injuries. The data from this study are consistent with previous reports of increased mortality from chronic renal disease in persons exposed occupationally to lead.     

Mortality in a cohort of antimony smelter workers

Animal studies show that antimonymay cause lung cancer and heart and lung disease in rodents. In exposed humans, ECG abnormalities and heart and lung disease have been reported. This mortality study of 1,014 men employed between 1937 and 1971 in a Texas antimony smelter consisted primarily of workers of Spanish ancestry (n = 928, 91.5%). Hispanics are known to smoke at much lower rates than non-Hispanics, and their lung cancer and heart disease mortality is generally low. When ethnic-specific Texas lung cancer death rates were used for comparison, mortality from lung cancer among antimony workers was elevated (SMR) 1.39, 90% CI 1.01-1.88), and we observed a significant positive trend in mortality with increasing duration of employment. When ischemic heart disease death rates from three different Spanish-surnamed populations were used for comparison, the rate ratios for mortality from ischemic heart disease were 0.91 (90% CI 0.84-1.09), 1.22 (90% CI 0.78-1.89), and 1.49 (90% CI 0.84-2.63). Pneumoconiosis/ other lung disease death rates for Spanish-surnamed men were unavailable and so calculation of rate ratios used white males as a comparison population (SMR 1.22; 90% CI 0.80-1.80). These data suggest some increased mortality from lung cancer and perhaps nonmalignant respiratory heart disease in workers exposed to antimony. However, conclusions are limited by possible confounders and the difficulty of identifying appropriate referent groups.     

Mortality of iron-steel workers in Anshan, China: a retrospective cohort study

Foundry workers have increased mortality and morbidity risks from numerous causes, including various cancers. A retrospective Chinese iron-steel cohort study was conducted to examine the mortality effects of exposure to foundry work. Standardized mortality ratios (SMRs) and standardized rate ratios (SRRs) were calculated to evaluate mortality risks among male workers with exposure to 15 hazardous factors, adjusting for confounders. During 14 years of follow-up, 13,363 of 121,846 male workers died. SMR analysis showed a healthy-worker effect in comparison with the general population. SRR analysis showed increased risks for all causes, all neoplasms, and others among the exposed workers compared with non-exposed blue-collar workers. Combined exposure to polycyclic aromatic hydrocarbons and two or more dusts increased the risks of lung cancer (SRR = 654; 95% CI: 113-3,780) and other malignancies. Foundry work has adverse health effects, including carcinogenic risks.     

Mortality and incidence of cancer among sewage workers: a retrospective cohort study.

To study the incidence of and mortality from cancer among sewage workers a retrospective analysis was performed on a cohort of 656 men employed for at least one year at any one of 17 Swedish sewage plants during the years 1965-86. Assessment of exposure was done by classification of work tasks. Lower than expected total mortality (standardised mortality ratio (SMR) = 0.75, 95% confidence interval (95% CI) 0.58-0.97) and cardiovascular mortality (SMR = 0.61, 95% CI 0.39-0.91) was found. This was interpreted as a result of the healthy worker effect. For all cancers combined the mortality (SMR = 1.08, 95% CI 0.68-1.67) and morbidity (SMR = 1.02, 95% CI 0.72-1.38) were comparable with those of the general population. There were increased incidences for brain tumours (SMR = 2.19, 95% CI 0.45-6.39), gastric cancers (SMR = 2.73, 95% CI, 1.00-5.94), and renal cancers (SMR = 1.68, 95% CI = 0.35-4.90). For lung cancer the risk was reduced (SMR = 0.70, 95% CI 0.15-2.05). Allowance for a latency period of 10 years from the start of exposure did not change the pattern. Logistic modelling was used to search for exposure-response relations. In a logistic model with the confounder age forced in, renal cancer had a significant positive relation with a weighted sum of employment times, where the weights describe the classification of exposure. No exposure-response relations were found for brain tumors or gastric cancers. The increased risks are based on small numbers of cases. A future follow up will add more conclusive power to the study. Specific exposures need to be identified to allow for a better dose-response analysis.     

Mortality of workers exposed to dieldrin and aldrin: a retrospective cohort study.

OBJECTIVE: To investigate the occurrence of long term health effects in humans exposed to aldrin and dieldrin, with an update of an earlier retrospective cohort mortality study. METHODS: A group of 570 workers employed between 1 January 1954 and 1 January 1970 either in a production or formulation plant were followed up for mortality until 1 January 1993. There were extensive industrial hygiene data available and biological monitoring data of aldrin and dieldrin for most of the workers. From these data individual estimates were made of the total intake of dieldrin. A total number of 2539.37 person-years at risk was added to the original study. RESULTS: 118 deaths were observed compared with 156 expected. No increase in mortality from liver cancer was found. However, there was an excess in mortality from rectal cancer. This excess was inversely related to the dose gradient. An analysis by job title did not show any excess cancer in any particular job. CONCLUSION: The study does not support a carcinogenic effect of dieldrin and aldrin in humans.     

Mortality and cancer incidence among Swedish dock workers--a retrospective cohort study

The study originates from the arousal of suspicions that, in connection with loading and unloading work involving the use of trucks, exposure to diesel exhaust fumes may be carcinogenic. This report describes a register study in which a broad mapping of the cause-of-death pattern and cancer morbidity has been carried out through the matching of locally compiled personal data with those from a central register, the Cause-of-Death Register, and the Cancer Register. The results obtained thus far show a low total mortality--irrespective of cause of death--but a tendency towards an excess risk for cancer morbidity, mainly due to lung cancer.     

Mortality and cancer incidence among secondary lead smelter workers.

OBJECTIVES--To examine the mortality pattern and the cancer incidence in a cohort of long term smelter workers exposed to lead. METHODS--The cohort consists of 664 male lead battery workers, employed for at least three months in 1942-87. From 1969 the values of all blood lead samples repeatedly obtained from these workers every two to three months, have been collected in a database. The expected mortality and morbidity 1969-89 was estimated from the county rates, specified for cause, sex, five-year age groups, and calendar year. Individual exposure matrices have been calculated and used for dose-response analyses. RESULTS--The total cohort showed an increased overall mortality (standardised mortality ratio (SMR) 1.44; 95% confidence interval (95% CI) 1.16-1.79), an increased mortality from ischaemic heart diseases (SMR 1.72; 95% CI 1.20-2.42) and all malignant neoplasms (SMR 1.65; 95% CI 1.09-2.44). These risk estimates were unaffected or slightly decreased when applying a latency period of 15 years, and no dose-response pattern was shown. The non-significantly raised cancer incidence in the gastrointestinal tract (11 malignancies) in the total cohort, increased to a barely significant level in the quartile with the highest cumulative lead exposure (standardised incidence ratio (SIR) 2.34, 95% CI 1.07-4.45). No clear dose response pattern was evident when further subdividing the data into those first employed up to 1969 v those first employed after 1969 when the blood lead monitoring programme started. The risk estimate for malignancies in the gastrointestinal tract was not related to latency time. The cancer incidence was not increased at other sites. CONCLUSIONS--A slightly increased incidence of gastrointestinal cancers was found in workers exposed to lead and employed before 1970. The lead cohort also showed an increased mortality from ischaemic heart diseases. These risk estimates did not show a dose-response pattern and were not associated with latency time. The results must also be interpreted with caution because of limited numbers, and lack of dietary and smoking data.     

Arsenic exposure and mortality: a case-referent study from a Swedish copper smelter

An increased mortality from lung cancer, cardiovascular disease, haematolymphatic malignancy and cirrhosis of the liver has been reported among smelter workers and others exposed to arsenic. This study uses the case-referent (case-control) technique and is concerned with workers in a copper smelter in a complex work environment, characterised by the presence of trivalent arsenic in combination with sulphur dioxide and copper, and also with other agents. Lung cancer mortality was found to be increased about five-fold and cardiovascular disease about two-fold, showing a dose-response relationship to arsenic exposure. Mortality from malignant blood disease (leukaemia and myeloma) and cirrhosis of the liver was also slightly increased. This mortality pattern among the smelter workers is consistent with earlier reports. An increased mortality from cardiovascular disease in this type of industry is of particular interest as it has been reported only once before.     

上海某冶炼厂铅接触工人肿瘤死亡的回顾性队列研究

目的 了解职业铅接触工人肿瘤死亡情况,探讨职业铅接触与肿瘤的关系。方法 1985年1月1日前在本厂工人1年以上,且1985年1月1日仍存活的男性工人共6971名组成全队列,其中3344名在铅接触车间工作的工人组成的亚队列为接触队列。随访从1985年1月1日至1997年12月31日。以上海市人口的肿瘤死亡率作为标准对照,计算标化死亡比（SMR）;以本厂非接触人群作内对照计算相对危险度（RR）;估计累计接触剂量进行剂量－反应关系分析。结果 全队列6971人共观察87576人年,接触队列3344人共观察41505人年。全队列中,肺癌的SMR（95％CI）为128．0（101．1－159．7）。1965年后入厂的工人肺癌的SMR为463．7（P＜0．01）。有铅接触工作史且工龄超过20年的工人鼻咽癌的SMR＝408．0（P＜0．01）,肺癌的SMR＝156．6（P＜0．01）。肿瘤总计、恶性肿瘤总计、食管癌、胃癌、肝和胆道癌、肺癌和膀胱癌的RR（95％CI）分别为3．25（2．43－3．89）、3．28（2．54－4．32）、3．57（1．08－10．47）、2．93（1．15－4．87）、4．58（2．03－9．97）、8．58（4．82－15．11）、6．66（2．83－13．01）。将累计接触剂量分为高、中、低3个组,中、高组工人恶性肿瘤RR分别为1．62（P＜0．05）和1．70（P＜0．05）,且有随累计接触剂量增加危险性升高的趋势。中、高组工人的肺癌RR分别为2．55（P＜0．05）,和2．31（P＜0．05）。结论 工人肿瘤死亡危险性升高可能与铅接触有关,但还需要在控制其他职业有害因素接触和非职业性有害因素接触的情况下作进一步的研究。     

Effects of low-level lead and arsenic exposure on copper smelter workers

An analysis of reported symptoms and their relationship with indicators of lead absorption--blood lead (Pb-B) and zinc protoporphyrin (ZPP)--and of arsenic absorption--urinary arsenic (As-U)--was undertaken among 680 active copper smelter workers. Lead and arsenic absorption in the copper smelter employees were characterized by the median values of 30.4 micrograms/dl for Pb-B, 41.5 micrograms/dl for ZPP, and 26 micrograms/L for As-U. Blood lead was 40 micrograms/dl or higher in 16.7% of cases, ZPP was 50 micrograms/dl or higher in 31.2%, and urinary arsenic was 50 micrograms/L or higher in 16.4% of currently active copper smelter workers. The number of reported symptoms (from a total of 14 symptoms) increased with ZPP levels; the relationship with Pb-B was less marked. Arsenic contributed relatively little. Mean Pb-B, ZPP, and As-U levels for subjects reporting each of the 14 symptoms were compared with those of subjects who did not report the symptoms. Mean Pb-B was found to differ significantly for one symptom, fatigue. Significant differences in mean ZPP levels were found for fatigue, sleep disturbances, weakness, paresthesia, and joint pain. Prevalence rates for these symptoms rose more markedly with increasing ZPP than with Pb-B levels. The results indicate a relationship between certain CNS and musculo-skeletal symptoms and increased lead absorption in this population. Adherence to exposure standards that preclude undue lead absorption and appropriate biological monitoring including ZPP levels, are necessary to prevent adverse, especially long-term, health effects.     

Mortality among Coast Guard Shipyard workers: A retrospective cohort study of specific exposures

In a previous analysis of a cohort of shipyard workers, we found excess mortality from all causes, lung cancer, and mesothelioma for longer work durations and in specific occupations. Here, we expand the previous analyses by evaluating mortality associated with 5 chemical exposures: asbestos, solvents, lead, oils/greases, and wood dust. Data were gathered retrospectively for 4,702 workers employed at the Coast Guard Shipyard, Baltimore, MD (1950–1964). The cohort was traced through 2001 for vital status. Associations between mortality and these 5 exposures were calculated via standardized mortality ratios (SMRs). We found all 5 substances to be independently associated with mortality from mesothelioma, cancer of the respiratory system, and lung cancer. Findings from efforts to evaluate solvents, lead, oils/greases, and wood dust in isolation of asbestos suggested that the excesses from these other exposures may be due to residual confounding from asbestos exposure.     

Mortality among workers from a plastics producing plant: a matched case-control study nested in a retrospective cohort study

Earlier proportional mortality studies of workers in a plastics producing plant in Massachusetts indicated excess mortality from certain digestive and genitourinary cancers. To more definitively examine mortality among these workers a retrospective cohort study was conducted for 2,490 male wage earners who worked at least one year during 1949-1966. Vital status was determined as of Dec. 31, 1976, for 99.7% of the cohort and death certificates were obtained for 98.0% of 603 observed deaths. Comparison with the local county white males revealed a slight excess in digestive system cancer (standard mortality ratio [SMR] = 101.8) and a statistically significant excess (p less than .05) in genitourinary cancer (SMR = 153.6). A relationship was suggested between cancer of the rectum, liver, and pancreas and both the duration and interval from onset of exposure. A secondary matched case-control study was conducted to determine if particular jobs or work areas were related to the excesses found in the primary study. This analysis did not support the hypothesis that digestive or genitourinary cancer was related to a general plant exposure or date of hire. Possible associations warranting continued surveillance were found between rectal cancer and cellulose nitrate production and between prostatic cancer and polystyrene processing. Digestive and genitourinary cancers other than rectal and prostate were not related to employment in any of 21 occupational exposure categories examined.     

Mortality study of a cohort of insulation workers

Cause specific mortality was investigated in a cohort of insulators employed by a company which operated in various parts of Italy. Follow-up covered the years 1960-1996. The cohort, which included 893 subjects, was derived from company files of relatively poor quality, which resulted in a high rate of lost to follow-up (10.1%) and of deaths with unknown cause (12.4%). The mortality experience of the cohort was contrasted with that of the Italian population. Overall mortality (SMR 141, 90% CI 118-167, 97 observed), and cancer mortality (SMR 165, 90% CI 123-216, 38 observed) were significantly increased. Among neoplasms, significant increases were observed for lung cancer (SMR 202, 90% CI 124-311, 15 observed), pleural neoplasms (SMR 2667, CI 90% 911-6103, 4 observed), and peritoneal neoplasms (SMR 1853, 90% CI 329-5832, 2 observed). The excess mortality for lung cancer was especially pronounced in subjects with latency time longer than ten years (SMR 237.1, 90% CI 140-377, 13 observed).     

Arsenic exposure and mortality: a case-referent study from a Swedish copper smelter.

An increased mortality from lung cancer, cardiovascular disease, haematolymphatic malignancy and cirrhosis of the liver has been reported among smelter workers and others exposed to arsenic. This study uses the case-referent (case-control) technique and is concerned with workers in a copper smelter in a complex work environment, characterised by the presence of trivalent arsenic in combination with sulphur dioxide and copper, and also with other agents. Lung cancer mortality was found to be increased about five-fold and cardiovascular disease about two-fold, showing a dose-response relationship to arsenic exposure. Mortality from malignant blood disease (leukaemia and myeloma) and cirrhosis of the liver was also slightly increased. This mortality pattern among the smelter workers is consistent with earlier reports. An increased mortality from cardiovascular disease in this type of industry is of particular interest as it has been reported only once before.     

Wood dust exposure and cancer incidence: a retrospective cohort study of furniture workers in Estonia

BACKGROUND: Occupational wood dust exposure is associated with increased risk of sinonasal cancer in men. However, little is known whether it is associated with sinonasal cancer in women or with malignancies of other sites. METHODS: In a retrospective cohort study of furniture workers, cancer incidence in 3723 men and 3063 women between 1968 and 1995 was compared to the incidence in the general population of Estonia. Cancer risks were analyzed by employment duration and occupation. RESULTS: The standardized incidence ratio (SIR) for all cancers did not differ significantly from one. Two men and one woman had sinonasal cancer (expected 1.07 and 0.53, respectively). Significantly increased risk of colon cancer was seen in the cohort (SIR 1.65, 95% confidence interval (CI) 1.22-2.17). Subjects employed for 10 years and over had significant excess of colon cancer (SIR 2.29, 95% CI 1.28-3.77) and rectal cancer (SIR 2.10, 95% CI 1.05-3.76) in the analysis by employment duration using exposure with a latency of 20 years. The nonsignificant excess of pharyngeal cancer in men (SIR 1.82) and lung cancer in women (SIR 1.43) was restricted to short-term workers. CONCLUSIONS: This study found an excess of colon and rectal cancer in furniture workers. There was no increase in total cancer risk.     

Leukaemia in benzene workers: a retrospective cohort study

A retrospective cohort study was conducted in 233 benzene factories and 83 control factories in 12 cities in China. The benzene cohort and the control cohort consisted of 28,460 benzene exposed workers (178,556 person-years in 1972-81) and 28,257 control workers (199,201 person-years). Thirty cases of leukaemia (25 dead and 5 alive) were detected in the former and four cases (all dead) in the latter. The leukaemia mortality rate was 14/100,000 person-years in the benzene cohort and 2/100,000 person-years in the control cohort; the standardized mortality ratio was 5.74 (p less than 0.01 by U test). The average latency of benzene leukaemia was 11.4 years. Most (76.6%) cases of benzene leukaemia were of the acute type. The mortality due to benzene leukaemia was high in organic synthesis plants followed by painting and rubber synthesis industries. The concentration of benzene to which patients with a leukaemia were exposed ranged from 10 to 1000 mg/m3 (mostly from 50 to 500 mg/m3). Of the 25 cases of leukaemia, seven had a history of chronic benzene poisoning before the leukaemia developed.