Cancer of the respiratory tract in nickel sinter plant workers: effect of removal from sinter plant exposure.

The risk of death due to cancer of the nose or lung was studied in nickel sinter plant workers during the period after they left the sintering operations. It was found that the excess risk of death from both diseases continued for many years after leaving the sinter plant. No effect of age at first exposure could be found. Possible explanations for the continued risk include an irreversible cellular change or the persistence of carcinogenic nickel compounds in the mucosa.     

Prevalence of small opacities in chest radiographs of nickel sinter plant workers.

Radiographs from 745 nickel sinter plant workers were taken and classified by five readers using the International Labour Office (1980) protocol. Each reader worked independently and the films were randomly mixed with films from a non-dust exposed office population and also with films from subjects known to have silicosis or asbestosis. The prevalence of small irregular opacities was selected as the outcome of interest. In the sinter workers this was within the range identified in cigarette smokers or in workers exposed to dusts of low fibrogenicity. Only minimal evidence of small round opacities was noted. There was no evidence from the chest radiographs that exposures to high concentrations of dusts containing compounds of nickel caused an inflammatory or fibrogenic response in the lungs of the exposed population.     

Respiratory cancer mortality and incidence in an updated cohort of Canadian nickel production workers

Respiratory cancer mortality and incidence were examined in an updated cohort of >56,000 Canadian nickel mining and refining workers. There was little evidence to suggest increased lung cancer risk in workers who had no experience in high-risk sintering operations that were closed by 1972, apart from that which would be expected from probable increased smoking prevalence relative to the comparison population. There was no substantive evidence of increased laryngeal cancer risk in the cohort, nor was there evidence of increased pharyngeal cancer risk in nonsinter workers. Nasal cancer incidence was elevated in nonsinter workers, but excess risks appeared to be confined to those hired prior to 1960. These findings lead us to tentatively conclude that occupationally-related respiratory risks in workers hired over the past 45 years are either very low or nonexistent.     

Nonrespiratory mortality and cancer incidence in a cohort of Canadian nickel workers

Mortality and cancer incidence were examined for an updated cohort of nonsinter nickel workers in Sudbury and Port Colborne, Ontario, Canada. Abstract results are provided for those with ≥ 15 years since first exposure. For circulatory disease mortality, significant elevations were observed overall in many Sudbury work areas and in Port Colborne staff. Underground miners, with first exposure before 1960, displayed significant elevations for pneumoconiosis, as well as silicosis and anthrasilicosis, likely due to crystalline silica. Significant elevations in colorectal cancer incidence were observed in Sudbury underground mining, mining maintenance, and maintenance work areas. Given a case-control study is not practical, the next cohort update should include more detailed occupational exposure assessment, including dust exposure, diesel engine emissions, solvents, various metals, silica, and sulphur dioxide.     

Mortality from lung cancer among a cohort of nickel cadmium battery workers: 1946-84.

The lung cancer mortality experienced by a cohort of 3025 workers from a nickel cadmium battery factory during the period 1946-84 has been investigated. Occupational histories were described in terms of 75 jobs: eight with "high," 14 with "moderate" or slight, and 53 with minimal or zero exposure to cadmium oxide (hydroxide) dust. The Mantel-Haenszel technique applied to prospective (or historical prospective) studies was used to compare the estimated cadmium exposures (durations of exposed employment) of those dying from lung cancer with those of matching survivors in the same year of follow up, while controlling for sex and year, and age of starting employment. Among workers first employed in the period 1923-46, there was some evidence of an association between the risk of dying from lung cancer and duration of employment in "high or moderate" exposure jobs, although the evidence relied heavily on the findings for the single highest exposure category. Among workers first employed in the period 1947-75, there was no evidence whatsoever of such an association.     

Retrospective cohort mortality study of cancer among sewage plant workers

There is little known about the incidence of cancer among sewage workers. In this paper we examine findings from a retrospective cohort study of 487 white male sewer authority workers employed between January 1950 and October 1979. Vital status was ascertained for 93% of the cohort yielding a total of 6,886 person years. Total mortality from all causes was comparable to that of the general white male U.S. population (Standardized Mortality Ratio [SMR] = 0.91, 95% Confidence Interval [CI] = 0.77-1.07). The cohort was subdivided into those not exposed, and sewer workers who were exposed to sewage effluent, sludge, or wastewater containing chemicals including potential carcinogens. Among the nonexposed group, mortality from all causes was significantly low (SMR = 0.55, 95% CI = 0.33-0.88). Among the exposed sewer workers, mortality from all causes was not significantly different from that of the general white male U.S. population (SMR = 1.00, 95% CI = 0.84-1.19). Mortality from all cancers among exposed sewer workers was slightly higher than that of the general population (SMR = 1.19, 95% CI = 0.79-1.7). Statistically significant elevated mortality ratios were seen for cancer of the larynx (SMR = 7.93, 95% CI = 1.59-23.96), and cancer of the liver (SMR = 5.4, 95% CI = 1.10-16.05). Careful study of the medical and occupational histories of these cases suggested that larynx cancer was possibly work-related, while liver cancer was not. A group estimated to be the highest exposed, composed predominantly of operatives, had a higher directly adjusted death rate from all malignant neoplasms combined compared to all other workers (rate ratio = 1.64). These findings of increased risk of cancer among exposed sewage workers, especially operators, are based on small number of cases and should be interpreted with caution. Studies of larger cohorts are needed to clarify the risk of these cancers among sewage workers.     

Lung cancer in workers in a nickel refinery

ABSTRACT This study is an analysis of the occurrence of lung cancer in nickel workers, particularly with regard to development time, histological types and tobacco smoking, in addition to specific exposure to nickel dust and fumes. It is a continuation of previous work in this field (Kreyberg, 1954a, b; 1962, 1969). The series consists of 44 cases of lung cancer occurring during the years 1948-74 in people currently or previously employed at Falconbridge nickel refinery. A seven-year period of reduced activity during the war enables lung cancer in workers who took up employment in 1927-39 to be compared with that in workers who started in or after 1946. It is confirmed that exposure to nickel dust and fumes increases the risk of developing lung cancer. However, all subjects with small cell anaplastic carcinoma and at least 25 out of 28 subjects with epidermoid carcinoma had been tobacco smokers. Four smokers and four non-smokers had Group II tumours. The mean age at diagnosis of lung cancer in the nickel workers corresponds closely with that of male subjects with lung cancer in general, in spite of the very wide differences in the development time, if this is related to the employment time in the refinery alone. The mean age at diagnosis is, however, consistent if the development time is related to the length of tobacco smoking. Tobacco smoking is an important factor in the development of lung cancer in nickel workers, and under the conditions described in this study the reduced carcinogenic influence may be attributable to reduced exposure to nickel and possibly also to tobacco.     

Incidence of cancer in a cohort of magnesium production workers.

The results from a cohort study on the incidence of cancer and the mortality in a cohort of 2391 male workers producing magnesium metal are presented. The study population was restricted to employees with more than one year of work experience in the study plant between 1951 and 1974 and the cohort was observed from 1953 to 1984. Altogether 152 new cases of cancer were observed versus 132.6 expected. Six cases of cancer of the lip were found against 2.3 expected, 21 of stomach cancer against 12.8 expected, and 32 of lung cancer against 18.2 expected. A possible causal relation between exposure to factors in the work environment and the development of cancer is discussed.     

Mortality from lung cancer among a cohort of nickel cadmium battery workers: 1946-84

The lung cancer mortality experienced by a cohort of 3025 workers from a nickel cadmium battery factory during the period 1946-84 has been investigated. Occupational histories were described in terms of 75 jobs: eight with "high," 14 with "moderate" or slight, and 53 with minimal or zero exposure to cadmium oxide (hydroxide) dust. The Mantel-Haenszel technique applied to prospective (or historical prospective) studies was used to compare the estimated cadmium exposures (durations of exposed employment) of those dying from lung cancer with those of matching survivors in the same year of follow up, while controlling for sex and year, and age of starting employment. Among workers first employed in the period 1923-46, there was some evidence of an association between the risk of dying from lung cancer and duration of employment in "high or moderate" exposure jobs, although the evidence relied heavily on the findings for the single highest exposure category. Among workers first employed in the period 1947-75, there was no evidence whatsoever of such an association.     

Cancer incidence and cancer mortality in a cohort of semiconductor workers.

The cancer mortality experienced by a cohort of 1807 workers from a semiconductor factory during the period 1970-82 has been investigated (as has cancer morbidity for 1970-81). Expectations for mortality were calculated on the basis of rates of mortality for the general population of England and Wales. Expectations for cancer incidence were calculated on the basis of incidence rates for the West Midland Region. For the total study cohort, observed numbers of deaths and incident cases for all cancers were close to expectation. For melanoma incidence, an observed of 3 cases was compared with an expectation of 0.68.     

Respiratory cancer in a cohort of copper smelter workers: results from more than 50 years of follow-up

Several studies have linked inhalation of airborne arsenic with increased risk of respiratory cancer, but few have analyzed the shape of the exposure-response curve. In addition, since inhaled airborne arsenic affects systemic levels of inhaled arsenic, there is concern that inhaled arsenic may be associated with cancers of the skin, bladder, kidney, and liver, which have been linked to ingested arsenic. The authors followed 8,014 white male workers who were employed for 12 months or more prior to 1957 at a Montana copper smelter from January 1, 1938 through December 31, 1989. A total of 4,930 (62%) were deceased, including 446 from respiratory cancer. Significantly increased standardized mortality ratios (SMRs) were found for all causes (SMR = 1.14), all cancers (SMR = 1.13), respiratory cancer (SMR = 1.55), diseases of the nervous system and sense organs (SMR = 1.31), nonmalignant respiratory diseases (SMR = 1.56), emphysema (SMR = 1.73), ill-defined conditions (SMR = 2.26), and external causes (SMR = 1.35). Internal analyses revealed a significant, linear increase in the excess relative risk of respiratory cancer with increasing exposure to inhaled airborne arsenic. The estimate of the excess relative risk per mg/m3-year was 0.21/(mg/m3-year) (95% confidence interval: 0.10, 0.46). No other cause of death was related to inhaled arsenic exposure.     

Respiratory cancer in Danish bakers: a 10 year cohort study.

A national cohort based on the census at 9 November 1970 and the death registration files from 1970 to 1980 was analysed to see if skilled Danish bakers had an excess of respiratory cancer. The group of skilled bakers was divided into occupational subgroups to try to narrow down the possible causes of cancer. Significant excess mortality was found among skilled bakers in retail bakeries, skilled bakers in hotels and restaurants, and independent bakers. To adjust for confounding factors, the SMR was calculated with control groups of equal social status and smoking habits. With all skilled workers as the reference group, skilled bakers in retail bakeries still had an excess, but now insignificant, risk but skilled bakers in hotels and restaurants had a significant excess risk. Compared with all self employed people in urban occupations in which an average of six or fewer workers were employed as a referent group, independent bakers had an insignificant excess risk. Suspected carcinogens in bakeries include polycyclic aromatic hydrocarbons (PAH), reaction products of PAH, free radicals, n-nitrosodimethylamine, aflatoxin, sterigmatocystin, and zeralenone.     

Mortality in a cohort of cement workers in a plant of Central Italy

Purpose  

Workers of cement production are exposed to alkaline dust with irritant effects on the respiratory system. Most previous studies have examined workers in cement/asbestos factories, but there is limited information of the effects of exposures to Portland cement alone. The present study examines the effects of cement dust in a cohort of Portland cement workers through the analyses of their mortality records.     

Retrospective cohort study of workers of a synthetic textiles plant in quebec: II. Colorectal cancer mortality and incidence

This paper describes standard mortality and nested case-control analyses of colorectal cancer for a cohort of synthetic textiles workers in which a cluster of five cases was observed previously. The cohort consisted of 7,487 men and 2,724 women who had more than 1 year's experience at the plant and who were either working in 1947 or were newly employed between 1947 and 1977. The Standardized Mortality Ratio (SMR) for colorectal cancer for men was 0.69 (95% confidence interval (CI): 0.52-0.92; 50 deaths) and for women it was 1.02 (95% CI: 0.57-1.69; 15 deaths). Among men only there was a suggestion that risks increased according to the length of service at the plant. In the nested case-control study, incident cases as well as deceased cases were included. A variety of analyses were carried out according to duration of employment in the processing units. For men the risk of colon cancer increased with duration of employment in the polypropylene and cellulose triacetate extrusion unit (unadjusted odds ratio (OR) for ≤5 years duration = 5.52; 95% CI: 1.12-27,26; 4 exposed cases). It was not possible, however, to provide an independent confirmation of this putative association because the case series included three of the original five cases. There was some evidence of increased risks in the cellulose acetate fiber manufacturing unit and in the dyeing and finishing unit, but the data were compatible with the null hypothesis of no effect. No associations were observed for employment in any of the other processing unit.     

Respiratory allergy in laboratory animal workers: a retrospective cohort study using pre-employment screening data.

OBJECTIVES: To study the role of exposure, atopy, and smoking in the development of laboratory animal allergy (LAA) in a retrospective cohort study. METHODS: Between 1977 and 1993, 225 people received a pre-employment screening when they started a job at a Dutch research institute where they were going to work with laboratory animals. After active follow up 136 of them (60.4%) could be traced and were sent a questionnaire with extensive questions on allergic symptoms, smoking habits, and job history. 122 people (89.7%) sent back a completed questionnaire. Those who were accepted for a job at the institute and did not have allergic symptoms at the start of the job were selected as cohort members. After selecting people with complete data on start and end date of jobs, exposure intensity, atopy, and smoking, the cohort consisted of 99 people with an average time of follow up of 9.7 years. LAA was defined as a positive response to a set of questions in the questionnaire. The mean number of hours a week a person was exposed to laboratory animals at entry of the cohort was used as a surrogate for exposure, and was divided into four categories. RESULTS: 19 cohort members (19.2%) reported LAA. More people with asthmatic symptoms were found in the high exposure categories. More atopic than non-atopic people reported asthmatic symptoms (13% v 6%). The mean time until development of symptoms of LAA was about 109 months in non-atopic people (n = 9), and 45 months in atopic people (n = 10) (t test; P < 0.05). Time until development of symptoms of LAA was shorter at a higher intensity of exposure, except for those exposed for less than two hours a week. A proportional hazard regression analysis showed that exposure and atopy were significant determinants of LAA. An increased relative risk (RR) was found for non-atopic people exposed to laboratory animal allergens for more than two hours a week. Atopic people had an even higher risk when exposed to laboratory animals for more than two hours a week (RR above 7.3). Sex, smoking, and age were not risk factors. More atopic than non-atopic people were absent from work or transferred because of allergies. CONCLUSIONS: This study showed that exposure and atopy are significant predictors of LAA and that the risk of developing LAA remained present for a much longer period (> 3 y) than considered before.     

Incidence of cancer in a cohort of magnesium production workers

The results from a cohort study on the incidence of cancer and the mortality in a cohort of 2391 male workers producing magnesium metal are presented. The study population was restricted to employees with more than one year of work experience in the study plant between 1951 and 1974 and the cohort was observed from 1953 to 1984. Altogether 152 new cases of cancer were observed versus 132.6 expected. Six cases of cancer of the lip were found against 2.3 expected, 21 of stomach cancer against 12.8 expected, and 32 of lung cancer against 18.2 expected. A possible causal relation between exposure to factors in the work environment and the development of cancer is discussed.