Increased risk of lung cancer in the melting department of a second Ontario steel manufacturer

A study of lung cancer among workers at an electric arc steel making operation was performed to follow up on the observation of a lung cancer cluster in the melt shop of another plant. The study group comprised 335 deceased men identified from plant records. Eight of thirty men who had ever worked in the pouring pit area died of lung cancer (PMR 276; p less than 0.01), but increased risk was not found elsewhere in the melting department. There was a significant trend in lung cancer risk with the length of employment in the pit area during a time window 18-30 years before death. Smoking data suggested that smoking alone could not account for the increased risk. An industrial hygiene assessment found present exposures to carcinogenic metals and silica to be within current guidelines. No polycyclic aromatic hydrocarbons were detected. This is the second steel plant for which we have found increased lung cancer risk in the pouring areas. The causative factors have not yet been identified.     

Mortality from asthma, chronic obstructive pulmonary disease, respiratory system cancer, and stomach cancer among paper mill workers: a case-referent study

In an earlier case-referent study from a soft-paper mill with levels of paper dust exceeding 5 mg/m3, an increased mortality was found (OR = 3.8, p less than 0.05) from asthma and chronic obstructive pulmonary disease (COPD) among the employed. Furthermore, other studies on paper mill workers have also indicated an increased mortality from lung cancer. The main objectives of the present case-referent study were to investigate the mortality from asthma. COPD, and lung cancer in two other Swedish paper mills. In these mills, the levels of paper dust have been below 3 mg/m3. The subjects for the study were all men who died between 1961 and 1985 from asthma and COPD (n = 31), respiratory cancer (n = 27), and stomach cancer (n = 33) selected in three parishes surrounding two paper mills. As referents we randomly selected about six times as many men who had died from nonmalignant nonrespiratory diseases in these parishes (n = 550). On the basis of information found in the personnel records in the mills, the men were classified into different occupational categories or as unexposed. No increased risk of asthma or COPD was found among the workers exposed to paper dust. However, it was found that there was significantly increased mortality (OR = 5.7, p less than 0.05) for asthma and COPD among workers in a previous log sorting department. The study also showed a significantly increased risk of lung cancer (OR = 2.1, p less than 0.05) among maintenance workers. There was no increased risk of stomach cancer in the study.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical measures, smoking, radon exposure, and risk of lung cancer in uranium miners.

OBJECTIVES: Exposure to the radioactive daughters of radon is associated with increased risk of lung cancer in mining populations. An investigation of incidence of lung cancer following a clinical survey of Ontario uranium miners was undertaken to explore whether risk associated with radon is modified by factors including smoking, radiographic silicosis, clinical symptoms, the results of lung function testing, and the temporal pattern of radon exposure. METHODS: Miners were examined in 1974 by a respiratory questionnaire, tests of lung function, and chest radiography. A random selection of 733 (75%) of the original 973 participants was followed up by linkage to the Ontario Mortality and Cancer Registries. RESULTS: Incidence of lung cancer was increased threefold. Risk of lung cancer among miners who had stopped smoking was half that of men who continued to smoke. There was no interaction between smoking and radon exposure. Men with lung function test results consistent with airways obstruction had an increased risk of lung cancer, even after adjustment for cigarette smoking. There was no association between radiographic silicosis and risk of lung cancer. Lung cancer was associated with exposures to radon daughters accumulated in a time window four to 14 years before diagnosis, but there was little association with exposures incurred earlier than 14 years before diagnosis. Among the men diagnosed with lung cancer, the mean and median dose rates were 2.6 working level months (WLM) a year and 1.8 WLM/year in the four to 14 year exposure window. CONCLUSIONS: Risk of lung cancer associated with radon is modified by dose and time from exposure. Risk can be substantially decreased by stopping smoking.     

Performance of different exposure assessment approaches in a study of bitumen fume exposure and lung cancer mortality

BACKGROUND: We compared performance of different exposure assessment approaches in a cohort study of cancer risk among European asphalt workers. METHODS: Three bitumen fume exposure indices (duration of exposure (years), average exposure (mg/m3) and cumulative exposure (mg/m3*years)) and two latency models (with and without a 15 year lag) were considered for an association between lung cancer mortality and bitumen fume. RESULTS: There was no association between lung cancer risk and either duration or cumulative exposure. However, there was the suggestion of an increase in lung cancer risk accompanying rise in average exposure. Only models with average bitumen fume exposure (with or without lag) improved model fit, albeit to the same extent. CONCLUSIONS: Constructing quantitative indices of exposure intensity was justified because they produced the greatest improvement in fit of models that explored possible relationship between bitumen fume exposure and lung cancer risk. The identified associations require further investigation.     

Low Plasma Cholesterol Predicts an Increased Risk of Lung-Cancer in Elderly Women

Background. There have been significant efforts in the United States to lower high cholesterol levels. Studies of men, however, have found a higher total cancer mortality rate at lower levels of plasma cholesterol. Many of these studies have found that lung cancer is more closely associated than other cancers with low cholesterol. Of the studies that include women, none has demonstrated a statistically significant inverse association between low cholesterol and lung cancer. Methods. We examined the relation between very low plasma cholesterol levels (<160 mg/dl) and lung cancer death in an 18-year prospective study of 2,011 men and 2,327 women. Results. After adjusting for age, body mass index, smoking, and education, the relative hazard of lung cancer mortality for those with low cholesterol (<160 mg/dl) compared with all other cholesterol levels (≥ 160 mg/dl) was 1.75 among men (P = 0.28) and 3.29 among women (P = 0.02). Excluding those who died within 5 years of baseline did not change the results. Conclusions. Both men and women with baseline plasma cholesterol levels <160 mg/dl were more likely to die of lung cancer. This difference was statistically significant in women. The association could not be explained by occult malignancy, smoking, or socioeconomic status.     

细胞色素P450基因多态及血清硒与肺癌的关系

目的 探讨细胞色素P450(A)(CYP1A1)的MSPI基因多态性、血清硒水平单独作用以及联合作用与肺癌发生危险性的关系。方法 采用成组病例一对照研究方法，病例58例，对照62例。用PCR-RFLP技术测定CYP1A1的MsPI多态性。用双道原子荧光光度计(GHAFS)测定血清硒水平。结果 CYP1A1的MsPI基因多态性单独作用时与肺癌危险性关系无显著性差异；病例组血清硒水平显著低于对照组(P=0．001)：以血清硒水平大于等于0．109mg／L。携带CYP1A1野生型者为参照组，则血清硒水平低于0．109mg／L且携带CYPlAl突变型或杂合型或携带野生型者OR分别为9．00(P=0．006)，3．94(P=0．195)，5．40(P=0．036)，而血清硒水平大于等于0．109mg／L携带突变型或携带杂合型者OR分别为1．69(P=0．500)，1．13(P=0．705)。结论 CYP1A1基因多态性单独作用时与肺癌发生无显著相关，血清硒水平与肺癌发生呈负相关；CYP1A1基因多态性与血清硒水平联合作用时明显提高肺癌发生的危险性，在肺癌发生中存在协同作用。     

Upper aerodigestive cancer in battery manufacturers and steel workers exposed to mineral acid mists.

OBJECTIVE--To assess the risk of cancer from inhalation of mineral acid mists. METHODS--A cohort study and nested case-control study of upper aerodigestive tumours were carried out in men employed since 1950 at two battery plants and two steel works in Britain. The cohort was identified from personnel records and included 2678 men with definite exposure to acid mists (mainly sulphuric acid), 367 with possible exposure, and 1356 who were unexposed. Mortality was compared with that in the national population by the person-years method. Cases of upper aerodigestive cancer were identified from death certificates and cancer registrations, and their exposure to acids was compared with that of age matched controls (five per case) from the same plant by conditional logistic regression. RESULTS--In follow up to 31 December 1993, 93% of men were traced, including 1277 who had died. Among the men definitely exposed to acid mists, overall mortality was less than in the national population (standardised mortality ratio (SMR) 0.92, 95% confidence interval (95% CI) 0.85-0.98) as was mortality from all cancers (SMR 0.92, 95% CI 0.79-1.05) and specifically from cancer of the larynx (SMR 0.48, 95% CI 0.01-2.70) and lung (SMR 0.98, 95% CI 0.78-1.22). A total of 15 incident or fatal cases of upper aerodigestive cancer were identified during follow up. When these men were compared with controls, risk was moderately increased in those who had worked for at least five years in jobs entailing exposures to sulphuric or hydrochloric acid in excess of 1 mg/m3 (OR 2.0, 95% CI 0.4-10). CONCLUSIONS--These findings are consistent with those from other studies which have indicated a hazard of upper aerodigestive cancer from acid mists. However, they indicate that any risk from exposures to sulphuric and hydrochloric acid below 1 mg/m3 is small.     

Residential randon exposure and lung cancer risk in Misasa, Japan: a case-control study

In order to investigate an association between residential radon exposure and risk of lung cancer, a case-control study was conducted in Misasa Town, Tottori Prefecture, Japan. The case series consisted of 28 people who had died of lung cancer in the years 1976-96 and 36 controls chosen randomly from the residents in 1976, matched by sex and year of birth. Individual residential radon concentrations were measured for 1 year with alpha track detectors. The average radon concentration was 46 Bq/m3 for cases and 51 Bq/m3 for controls. Compared to the level of 24 or less Bq/m3, the adjusted odds ratios of lung cancer associated with radon levels of 25-49, 50-99 and 100 or more Bq/m3, were 1.13 (95% confidence interval; 0.29-4.40), 1.23 (0.16-9.39) and 0.25 (0.03-2.33), respectively. None of the estimates showed statistical significance, due to small sample size. When the subjects were limited to only include residents of more than 30 years, the estimates did not change substantially. This study did not find that the risk pattern of lung cancer, possibly associated with residential radon exposure, in Misasa Town differed from patterns observed in other countries.     

Mortality of nitrate fertiliser workers.

An epidemiological cohort study was conducted to investigate the mortality patterns among a group of workers engaged in the production of nitrate based fertilisers. This study was designed to test the hypothesis that individuals exposed to high concentrations of nitrates might be at increased risk of developing cancers, particularly gastric cancer. A total of 1327 male workers who had been employed in the production of fertilisers between 1946 and 1981 and who had been occupationally exposed to nitrates for at least one year were followed up until 1 March 1981. In total, 304 deaths were observed in this group and these were compared with expected numbers calculated from mortality rates in the northern region of England, where the factory was located. Analysis was also carried out separately for a subgroup of the cohort who had been heavily exposed to nitrates--that is, working in an environment likely to contain more than 10 mg nitrate/m3 for a year or longer. In neither the entire cohort nor the subgroup was any significant excess observed for all causes of mortality or for mortality from any of five broad categories of cause or from four specific types of cancer. A small excess of lung cancer was noted more than 20 years after first exposure in men heavily exposed for more than 10 years. That men were exposed to high concentrations of nitrate was confirmed by comparing concentrations of nitrates in the saliva of a sample of currently employed men with control men, employed at the same factory but not in fertiliser production. The men exposed to nitrate had substantially raised concentrations of nitrate in their saliva compared with both controls within the industry and with men in the general population and resident nearby. The results of this study therefore weight against the idea that exposure to nitrates in the environment leads to the formation in vivo of material amounts of carcinogens.     

Mortality of nitrate fertiliser workers

An epidemiological cohort study was conducted to investigate the mortality patterns among a group of workers engaged in the production of nitrate based fertilisers. This study was designed to test the hypothesis that individuals exposed to high concentrations of nitrates might be at increased risk of developing cancers, particularly gastric cancer. A total of 1327 male workers who had been employed in the production of fertilisers between 1946 and 1981 and who had been occupationally exposed to nitrates for at least one year were followed up until 1 March 1981. In total, 304 deaths were observed in this group and these were compared with expected numbers calculated from mortality rates in the northern region of England, where the factory was located. Analysis was also carried out separately for a subgroup of the cohort who had been heavily exposed to nitrates--that is, working in an environment likely to contain more than 10 mg nitrate/m3 for a year or longer. In neither the entire cohort nor the subgroup was any significant excess observed for all causes of mortality or for mortality from any of five broad categories of cause or from four specific types of cancer. A small excess of lung cancer was noted more than 20 years after first exposure in men heavily exposed for more than 10 years. That men were exposed to high concentrations of nitrate was confirmed by comparing concentrations of nitrates in the saliva of a sample of currently employed men with control men, employed at the same factory but not in fertiliser production. The men exposed to nitrate had substantially raised concentrations of nitrate in their saliva compared with both controls within the industry and with men in the general population and resident nearby. The results of this study therefore weight against the idea that exposure to nitrates in the environment leads to the formation in vivo of material amounts of carcinogens.     

High-fat foods and the risk of lung cancer.

We conducted a population-based case-control study of the association of dietary cholesterol and fat with lung cancer between 1983 and 1985 on Oahu, Hawaii. The study population included 226 men and 100 women with lung cancer, and 597 male and 268 female community controls matched for age (+/- 5 years) and sex. There was a positive dose-response relation between the consumption of processed meats (luncheon meats, bacon, sausage), dairy foods (whole milk, regular ice cream), eggs, and particular desserts (fruit pies, custard/cream pies) and the risk of lung cancer in men. We also found a positive trend in the risk of lung cancer in women with increasing intake of some processed meats (bacon, Spam) and desserts (cakes, custard/cream pies). The dose-response relation tended to be stronger among men who were heavy smokers and who were diagnosed with squamous cell cancer of the lung. A positive trend in risk was found for nitrite intake in men and dimethylnitrosamine intake in men and women. These data indicate that smokers with a high intake of foods rich in fat and animal protein or who have a preference for cured meats are at increased risk of lung cancer.     

Dietary cholesterol and incidence of lung cancer: the Western Electric Study.

The hypothesis that dietary cholesterol is positively associated with lung cancer was investigated in a 24-year cohort study of 1,878 middle-aged men who were employed in 1958 by the Western Electric Company in Chicago. The relative risk of lung cancer associated with an increment in dietary cholesterol of 500 mg/day was 1.9 (95 percent confidence interval 1.1-3.4) after adjustment for cigarettes, age, and intake of beta-carotene and fat. Results suggested that the association was specific to cholesterol from eggs. Further research is needed to understand the basis for this association.     

The effects of non-response in a prospective study of cancer: 15-year follow-up

Out of 11,136 Japanese men identified on the island of Oahu, Hawaii in 1965 by the Honolulu Heart Program, 8006 responded to a mailed questionnaire and were examined. Some 1871 responded only to the mailed questionnaire, and 1259 did not respond at all. After 15 years of follow-up, the examined men had significantly lower risk of death from all causes and death from cancer. Minor differences were also noted between the two groups in the risk of cancer of the lung, stomach, colon, and rectum. However, the examined men had a significantly higher risk of prostate cancer. In general, the strength of these non-response effects was mainly due to risk differences in the first five years of the 15-year follow-up period. The relative risk (RR) of each of the seven endpoint events tended towards 1.0 as each of the three successive five-year follow-up intervals were considered. An exception to this was the prostate cancer incidence RR which favoured the unexamined men throughout the entire 15 years, but significantly so only in the last five-year follow-up interval. When the 8006 examined and 1871 unexamined men who responded to the mailed questionnaire were evaluated with respect to the association of cigarette smoking with lung cancer incidence, the RR for smokers was 9.77 for the examined men, and 6.73 for the unexamined men. Since these RRs are not significantly different, there should be little bias in RR estimates of cigarette smoking for lung cancer if the observation was limited to only the examined men. With regard to the association of body mass index (BMI) with colon cancer in older men, the RRs for men in the highest BMI quintile were quite comparable, at 1.37 for the examined group and 1.60 for the unexamined men. We conclude that although some non-response effects on cancer incidence exist in this cohort, they do not appear to be serious enough to have changed conclusions drawn about risk relationships.     

Respiratory cancer in a cohort of nickel sinter plant workers.

A study was undertaken of a cohort of nickel refinery workers from a sinter plant that operated from 1948 to 1962. A complete follow-up of the 495 workers has been carried out by searching death records and other measures. Incidence cases known to the Workmen's Compensation Board of Ontario have been included. Fifty-four cases of lung cancer and eight of sinus cancer (including two in men who subsequently developed primary lung cancer) were located. The risk of lung and sinus cancer was much higher in the earlier days of operation of the plant, with an increase rate of over 40% for those employed in the first year of operation. The dose-response relationship has been examined by regressions of standardised morality ratios (SMR) and standardised incidence ratios (SIR). The SIR suggests that the risk doubled at levels of exposure of 12 months (six months in the earlier years).     

Lung cancer in mild steel welders

To investigate lung cancer risk, the authors conducted a historical cohort mortality study of 4,459 mild steel welders who had been employed at three midwestern plants which manufactured heavy equipment. Follow-up began in the mid-1950s and extended through 1988. All welders had at least 2 years welding experience (average duration, 8.5 years). This cohort had no occupational exposure to asbestos or stainless steel fumes (containing nickel and chromium), two potential confounders in previous welders studies. A comparison population of 4,286 nonwelders, all with at least 2 years employment at the same plants, was also studied. Nonwelders had never been welders and were allowed to have no more than 90 days employment as a painter, foundryman, or machinist. Sampling data collected from 1974-1987 indicated that welders were exposed to 6-7 mg/m3 of total particulate and 3-4 mg/m3 of iron oxide, while nonwelders had negligible exposures to welding fumes. When compared with the United States population, both welders and nonwelders had elevated rates for lung cancer (standardized mortality ratios (SMRs): welders, SMR = 1.07; nonwelders, SMR = 1.17), but neither SMR was significantly elevated. Limited smoking data based on a 1985 survey indicated that both welders and nonwelders smoked more than the United States population, possibly accounting for part of their elevated lung cancer rates. There was no trend of increased risk for welders with increased duration of exposure. The only other cause of death significantly elevated was emphysema among welders. Nonmalignant respiratory disease was not elevated for welders (SMR = 0.96). When welders were compared with nonwelders directly for lung cancer, the rate ratio was 0.90.     

Does vasectomy cause prostate cancer?

Vasectomy is the process in which a man's vas deferens are severed, with the cut ends folded back and tied off to prevent the release of sperm from his testicles to the urethra and out of the penis. The procedure may be conducted in a doctor's office under local anesthesia, is almost 100% effective in preventing pregnancy, and leaves sexual function fully intact. Since sperm comprise less than 5% of semen, even the amount of ejaculated fluid does not change noticeably. 20% of American men over age 35 years have had a vasectomy. Despite vasectomy's simplicity and effectiveness, debate exists over whether vasectomy may increase the risk of prostate cancer, the most common malignancy in men. Two large, well-designed Harvard studies were published in 1993 in the Journal of the American Medical Association which suggest that such a relationship may exist. The two studies compared the number of prostate-cancer diagnoses in almost 25,000 men who had undergone vasectomy with nearly 50,000 men who had not. Men who had undergone vasectomy more than 20 years earlier were almost twice as likely as their unsterilized counterparts to have been diagnosed with prostate cancer. Overall, the rate of such diagnoses was about 60% higher among the men who had been sterilized. These widely-reported studies rekindled earlier fears of a possible prostate-cancer risk and no doubt convinced some men to avoid the operation or to have it reversed if they had already gone through with it. Four earlier studies also suggested a link between prostate cancer and vasectomy. Seven other reports, however, have found no connection. Several studies even indicate that men who undergo vasectomy live longer than other men. Many researchers believe that the Harvard studies' findings are simply the result of earlier and better diagnosis of prostate cancer among sterilized men rather than due to an actual increased risk of the cancer.     

Mortality of a cohort of men in a silicosis register: further evidence of an association with lung cancer

Lung cancer mortality from 1980 to 1986 was studied in a cohort of 1,419 men in a silicosis register who had no previous exposure to asbestos and polyaromatic hydrocarbons. The 28 deaths from lung cancer were statistically in excess of expected (SMR 2.03; 95% CI 1.35-2.93). Excess risks of lung cancer were found in both underground workers (SMR 3.41; 95% CI 1.10-7.97; based on 5 deaths) and surface workers (SMR 1.87, 95% CI 1.18-2.81; based on 23 deaths). All lung cancer deaths were smokers. There was an increase in SMRs with longer latency periods and years of exposure, with the greatest risk found in those who had worked for 30 or more years after more than 30 years since first exposed (SMR 3.07, based on 16 deaths). The risk for lung cancer was higher in those with tuberculosis (SMR 2.52; 95% CI 1.52-3.94) and showed an increasing trend with severity of silicosis, from category 1 to 3 and from category A to C, with highest risk in those with tuberculosis and category 3 (SMR 4.44 based on 3 deaths) or tuberculosis and category C (SMR 7.63 based on 7 deaths). Most of the excess lung cancer risk in silicotics is due to smoking, but a synergistic effect between smoking and silica/silicosis on the risk of lung cancer is also likely. In particular, a possible role of silicosis and tuberculosis as the fibrotic seedbed for malignant growth in the lung is strongly supported.     

The effect of dietary cholesterol and fat on the risk of lung cancer in Hawaii

A population-based case-control study of the association between dietary lipids and lung cancer was carried out in Hawaii between March 1983 and October 1985. The sample included 226 men and 100 women with lung cancer and 597 male and 268 female controls, frequency-matched to the cases on sex and five-year age group. Personal interviews were conducted in the home by trained interviewers using a quantitative diet history method. The items in the questionnaire were chosen to provide an estimate of 85% or more of the intakes of dietary cholesterol and fat for individuals in each of the five ethnic groups included in the study. The results showed a significant positive association of dietary cholesterol and the risk of lung cancer in men, but not in women. The odds ratio for the risk of lung cancer among men in the highest compared with the lowest quartile of cholesterol intake was 2.2 (95% confidence interval 1.3-3.8). Although there was a significant trend (p less than 0.05), the effect of cholesterol suggested a threshold rather than a continuous gradient. The association of cholesterol and lung cancer was consistent for three of four ethnic groups analyzed separately. These results confirmed earlier findings by these investigators. The effect of cholesterol on the development of lung cancer was restricted to current cigarette smokers who smoked tobacco heavily and to squamous and small cell histologic types of lung cancer. Similar results were found for total, saturated, and, to some extent, unsaturated dietary fat, but because of the high correlation between fat and cholesterol (r = 0.76 for total fat and cholesterol), it was not possible to separate the effects of these nutrients.     

Incidence of laryngeal cancer and exposure to acid mists.

To determine the relation between exposure to acid mist and laryngeal cancer, the smoking habits, drinking habits, and incidence of laryngeal cancer of 879 male steelworkers exposed to acid mists during pickling operations was ascertained. Sulphuric acid mist was the primary exposure for most men in this cohort. These men had all worked in a pickling operation for a minimum of six months before 1965, with an average duration of exposure of 9.5 years. Exposures to sulphuric acid in the 1970s averaged about 0.2 mg/m3, and earlier exposures were probably similar. Interviews were conducted with all cohort members or their next of kin in 1986 and medical records of decedents were reviewed. Nine workers were identified who had been diagnosed as having laryngeal cancer, using a conservative case definition that required medical record confirmation for any case among decedents and confirmation by a physician for any case among live individuals. Using data from national surveys of cancer incidence as referent rates, 3.44 laryngeal cancers would have been expected. Excess smoking by the exposed cohort compared with the United States population resulted in an upward adjustment of the expected number of cases of laryngeal cancer to 3.92. The standardised incidence rate ratio for laryngeal cancer was 2.30 (9/3.92), with a one sided p value of 0.01 (assuming a Poisson distribution). The finding of excess laryngeal cancer in this cohort is consistent with four other studies published since 1981.