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Query: UMLS:C0242379 (lung cancer)
 71,905 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Selenium is considered an essential trace element in most animal and plant species, although still reported in many texts as a highly toxic material. Epidemiological investigations have reported an inverse relationship between selenium and lung cancer. Explanations of reported observations have resulted in numerous mechanistic theories. Only recently have selenium metabolites involved in excretion been considered potential agents for antilung cancer activity. Anticancer properties have been shown in occupationally exposed copper smelter workers, dietary investigations and experimental studies. Supplementation with selenium of public water supplies, as is currently done with fluoride, is a potential method for increasing the blood concentration. This may permit development of a population prevention strategy against lung cancer and other diseases.
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PMID:Antilung cancer activities of selenium. 365 23

In observational cohort mortality studies with prolonged periods of exposure to the agent under study, independent risk factors for death commonly determine subsequent exposure to the study agent. For example, in occupational mortality studies, date of termination of employment is both a determinant of subsequent exposure to the chemical agent under study (since terminated individuals receive no further exposure) and an independent risk factor for death (since disabled individuals tend to leave employment). When a risk factor determines subsequent exposure and is determined by previous exposure, standard analyses that estimate age-specific mortality rates as a function of cumulative exposure can underestimate the true effect of exposure on mortality, whether or not one adjusts for the risk factor in the analysis. This observation raises the question, "Which, if any, empirical population parameter can be causally interpreted as the true effect of exposure in observational mortality studies?" In answer, we offer a graphical approach to the identification and estimation of causal parameters in mortality studies with sustained exposure periods. We reanalyze the mortality experience of a cohort of arsenic-exposed copper smelter workers using our approach and compare our results with those obtained using standard methods. We find an adverse effect of arsenic exposure on all cause and lung cancer mortality, which standard methods failed to detect. The analytic approach introduced in this paper may be necessary to control bias in any epidemiologic study in which there exists a risk factor which both determines subsequent exposure and is determined by previous exposure to the agent under study.
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PMID:A graphical approach to the identification and estimation of causal parameters in mortality studies with sustained exposure periods. 366 61

Previous studies of the relationship between arsenic levels and respiratory cancer among copper smelter workers have not directly accounted for possible effects of SO2 exposure and cigarette smoking. This is a report on the 1949-1980 mortality experience of 6,078 white male workers who worked at least 3 years between 1 January 1946 and 31 December 1976 at one or more of eight US copper smelters. The completeness of the cohort was verified statistically, and worker exposures to arsenic, SO2, dust, nickel, cadmium, and lead were estimated from retrospective industrial hygiene surveys reported elsewhere. By using internal controls, a dose-response relationship for lung cancer was observed with exposure to arsenic and SO2. When cigarette smoking data were included with arsenic and SO2 exposure data in a nested case-control analysis, only smoking and arsenic were statistically significant factors. The arsenic-lung cancer relationship was confined to a single smelter associated with high content feed. In the remaining smelters mortality for all causes of death and for all cancer was not high based on comparisons with national, state, and local rates.
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PMID:Some effects of cigarette smoking, arsenic, and SO2 on mortality among US copper smelter workers. 368 94

Increased mortality due to various malignancies is reported from long-term exposed, non-ferrous smelter workers. In the present study the post-mortem distribution of cadmium, lead and zinc in lung, liver and kidney is reported and related to exposure and mortality. The study involved 86 male copper smelter workers who died after April 1975. Lung samples were taken from all workers and liver and kidney samples were taken from about one-quarter of the workers. Two control groups were used. The exposed workers were divided into six groups based upon diagnoses in medical records and autopsy protocols. Lead and zinc were analyzed by atomic absorption spectrophotometry and cadmium by neutron activation analysis. For the skewly distributed tissue levels, non-parametric statistical processing was used. Of the workers, 53% died from cardiovascular diseases and 30% from malignancies (8% from lung cancer). Cardiovascular diseases predominated in the two control groups: about 75 and 100%, respectively. Lung and liver cadmium concentrations were significantly higher in the lung cancer group of smelter workers than in the other groups of smelter workers (p less than 0.05) and rural controls (p less than 0.01). Cadmium in kidney, and lead in lung and liver were significantly higher (p less than 0.03) in the lung cancer group than in rural controls, but did not differ from that of the other workers. Zinc in lung, liver and kidney did not differ between exposed workers and controls. Rather strong Spearman rank-order correlation coefficients were found between the cadmium content of lung, liver and kidney tissue, especially in non-smoking smelter workers and rural controls. Smoking was more common in the lung cancer group than in the total group of smelter workers. Cadmium levels in the lungs of exposed workers were significantly higher (p less than 0.001) in smokers than in both ex-smokers and non-smokers. Earlier studies of the same workers gave significantly lower selenium levels in lung tissue compared with other groups of smelter workers and controls. As other carcinogenic substances are present in the working environment, e.g. arsenic, chromium and benzo [alpha]-pyrene, the specific effect of cadmium in the development of lung cancer cannot be evaluated at present.
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PMID:Distribution of cadmium, lead and zinc in lung, liver and kidney in long-term exposed smelter workers. 370 26

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.
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PMID:Mortality and lead exposure: a retrospective cohort study of Swedish smelter workers. 377 40

This paper reviews studies on the adverse health effects of exposure to metals, using arsenic and cadmium as examples. The carcinogenic potential of arsenic has been studied in various settings. Inhalation is clearly related to the development of lung cancer in (copper) smelting and arsenical pesticide manufacturing, and also in heavily exposed wine merchants who had an additional source of exposure by ingestion. Animal studies have shown cadmium to be a lung carcinogen, while a study by Thun et al. provides the best evidence to date that cadmium inhaled as CdO particles may be a human lung carcinogen. On the basis of this latter study, EPA estimates the risk due to cadmium at 1.8 X 10(-3) cases/micrograms/m3, which results in more than 100,000 excess lung cancers (lifetime). For arsenic, the risk estimate of 4.29 cases/1,000 micrograms/m3, based on epidemiologic data also results in more than 100,000 lung cancers (lifetime). This paper reviews the bases for these estimates and presents recommendations for further research. Lung cancer risks also exist for other metals such as nickel, chromium, and beryllium. Further study is required before a definitive conclusion can be reached about the significance and magnitude of environmental exposures to metals as a cause of lung cancer.
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PMID:Contribution of metals to respiratory cancer. 383 Jan 15

A correlation study linking age-adjusted lung cancer mortality rates with indices of air pollution was conducted as a first step in the investigation of the high rate of lung cancer in Liaoning Province. Mortality rates for this cancer during 1976-78 for males and females were elevated in the large industrial cities with metallurgical processing and machinery manufacturing industries, after smoking was taken into account. However, there was little correlation between measures of total suspended particulates and lung cancer rates across the 10 major cities of the Province. Neighborhood air pollution indices correlated significantly with local commune mortality rates within the largest city, and lung cancer rates were higher near certain point sources of industrial pollution (including a copper-zinc smelter). These findings indicate that the atmospheric pollution in this northern Chinese province may contribute to lung cancer risk and that further analytic epidemiologic study in this high-risk area is warranted for evaluation of the role of outdoor and indoor air pollutants.
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PMID:Air pollution and lung cancer in Liaoning Province, People's Republic of China. 383 46

In cancer process there have been found metabolic changes in several elements, especially in respect to copper. It has been proved that there is an alteration in the serum levels of some metals, and in their distribution in the proteins binding them. On the other hand, there exist, also, ceruloplasmin differences between patients serum and the control. Our work has been carried out to study the trace element metabolism in lung cancer, as well as chromium and zinc contents. Electrophoretic techniques have been applied to study the protein levels.
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PMID:[Determination of trace elements, ceruloplasmin and blood proteins in pulmonary neoplasms]. 388 Jan 59

Etiologic factors for lung cancer were studied by the case-control technique among 636 men, including 212 with pulmonary carcinoma, who had died between 1961 and 1979 in a county in northern Sweden. Data on smoking habits, occupation, and residence were obtained from a next of kin to each study subject. Validation against data from other sources indicated that the exposure information was of high quality. A relative risk of 2.0 for lung cancer was seen among men who had lived within approximately 20 km from a large copper smelter. The increased risk, which is statistically significant (p less than 0.05), could not be explained by smoking habits or occupational background. Smelter workers and miners had relative risks for lung cancer of 3.0 and 4.1, respectively. No firm conclusions can be drawn on the cause of excess lung cancer risk in the smelter area, but it seems plausible that the very substantial emissions to air from the smelter, especially of arsenic, may have played a role.
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PMID:Lung cancer mortality among men living near an arsenic-emitting smelter. 402 8

A possible protective effect of selenium against lung cancer has been indicated in recent studies. Workers in copper smelters are exposed to a combination of airborne selenium and carcinogens. In this study lung tissue concentrations of selenium, antimony, arsenic, cadmium, chromium, cobalt, lanthanum, and lead from 76 dead copper smelter workers were compared with those of 15 controls from a rural area and 10 controls from an urban area. The mean exposure time for the dead workers was 31.2 years, and the mean retirement time after the end of exposure 7.2 years. Lung cancer appeared in the workers with the lowest selenium lung tissue levels (selenium median value 71 micrograms/kg wet weight), as compared with both the controls (rural group, median value 110; urban group, median value 136) and other causes of death among the workers (median value 158). The quotient between the metals and selenium was used for comparison: a high quotient indicating a low protective effect of selenium and vice versa. The median values of the quotients between antimony, arsenic, cadmium, lanthanum, lead, chromium, and cobalt versus selenium were all numerically higher among the cases of lung cancer, the first five significantly higher (p less than 0.05) in 28 of the 35 comparisons between the lung cancer group and all other groups of smelter workers and controls. The different lung metal concentrations for each person were weighted according to their carcinogenic potency (Crx4 + Asx3 + Cdx2 + Sbx1 + Cox1 + Lax1 + Pbx1) against their corresponding selenium concentrations. From these calculations the protective effect of selenium was even more pronounced.
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PMID:Protective effect of selenium on lung cancer in smelter workers. 404 90


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