Increased risk for primary liver cancer among women exposed to solvents.

An earlier case-referent study by the same authors [Int Arch Occup Environ Health 54 (1984) 147-153] reported that solvent-exposed women, but not men, had an increased risk for primary liver cancer. The present study was undertaken to verify these results. The relatives of deceased patients, ie, 377 liver cancer cases, 385 coronary infarction referents, and 476 stomach cancer referents, responded to a questionnaire on past employment and potentially relevant covariables, the response rates being 71.7, 72.7, and 69.0%, respectively. The information was assessed for solvent exposure by two occupational hygienists without knowledge of the patients' diagnoses. Seven male and seven female liver cancer cases had been exposed to solvents, the odds ratio being less than 1 for the men but greater than 3 for the women irrespective of the reference group used for comparison. The results confirm the authors' earlier findings. When both materials were combined, the odds ratio was 7.8 for the female liver cancer cases as compared with the infarction referents. In the combined material, nine female liver cancer cases, two stomach cancer referents, but no infarction referent had had at least probable exposure to chlorinated hydrocarbons. Such exposure was rare among all of the men in the study. This finding may explain why the increased liver cancer risk occurred only for the women, although a sex difference in sensitivity cannot be completely ruled out.

Incidence of cancer among welders, platers, machinists, and pipe fitters in shipyards and machine shops.

The incidence of cancer in 12,693 shipyard and machine shop male workers (1689 welders, 4308 platers, 6003 machinists, 693 pipe fitters) employed for at least one year between 1945 and 1960 was investigated in a retrospective cohort study. The welders had welded only mild steel and had not been exposed to hexavalent chromium containing fume. The follow up was 99.7% complete and the total number of person-years was 304,682. The incidence of cancer in 1953-81 was ascertained through the Finnish Cancer Registry. The observed numbers of cases of cancer were compared with the expected numbers based on regional urban rates. The smoking habits of the cohort were surveyed with a postal questionnaire sent to a sample of 961 workers. The smoking habits of the cohorts were similar and smoking was not more common than among the general population. The total number of cases of cancer was 611 (exp 629) among the shipyard workers and 376 (exp 388) among the machine shop workers. The incidence of lung cancer was increased among the shipyard workers (obs 227, exp 192). This excess was observed in all the worker groups and was most evident for the pipe fitters and platers. Among the machine shop workers, the incidence of lung cancer was lower than expected with the exception of the welders who had a slightly raised risk of lung cancer (obs 14, exp 10). The incidence of laryngeal cancer was slightly raised among the shipyard workers (obs 24, exp 20) but not in the machine shop workers. No excess risk was observed among the welders. The incidence of cancer of the prostate was increased among the machine shop workers (obs 39, exp 31) but not in the shipyard workers. The excess was statistically significant for the welders. No pronounced excess could be found for other types of cancer. Analysis by the duration or exposure showed that the excess of lung cancer in the shipyard workers was most evident during the last period of observation (1972-81). No other trends were obvious and the slight excess of lung cancer observed among the welders did not increase with increasing follow up time. No excess risk for mesothelioma was found. The small excess of lung cancer in welders could be due to chance. The fact that only a small and statistically insignificant excess of lung cancer could be found among this group of heavily exposed welders suggest that if the risk of lung cancer was associated with welding this risk must nowadays be low and probably too low to be unequivocally detected in most epidemiological studies.

A cancer register-based case study of occupations of patients with acute myeloid leukemia.

All 636 cases of acute myeloid leukemia (AML) reported to the Finnish Cancer Registry between 1971 and 1977 inclusive were compared with patients with other forms of cancer (non-AML) from the same registry. We found no increasing trend in the incidence of AML for either sex, but we found some evidence for regional clusters in certain provinces of Finland. A statistically significant higher incidence was found for men than women in the age group of 50 to 80 years. Classification according to occupation at the time of diagnosis revealed no statistically significant differences between the leukemia cases and the patients with other forms of cancer, but forestry work was more common among the men with AML, and both health care and food industry work were more common among the women with AML. Classification for exposure to chemicals, solvents, or drugs did not yield any statistical differences. The results were inconclusive with regard to the possible role of occupational factors in the etiology of acute myeloid leukemia.

Congenital malformations, mortality and styrene exposure.

The prevalence of congenital malformations among children born to styrene-exposed male and female workers, as well as the mortality of the exposed workers, was studied. A cohort of 2,209 workers (1,698 men, 511 women) was selected from the personnel files of 160 workplaces using styrene in the manufacture of reinforced plastic products. The earliest exposure histories began in 1960, but the majority of workers had been exposed after 1967. The data on children born to the exposed workers were linked with those of the Register of Congenital Malformations. The number of malformations of children born to the workers was, both before and during the styrene exposure, below the expected values. In the cohort there were 37 observed deaths (expected 74.0), six of which were due to cancer (expected 13.0). The cancer sites were the stomach (2 cases), bronchus (1), breast (1), ovary (1), and kidney (1 case). There were no cases of lymphatic or haematopoietic cancer. Most of the cancers appeared after short exposure times and soon after the commencement of exposure.

Primary liver cancer and exposure to solvents.

A case-referent study was done on the possible association between primary liver cancer (ICD 155.0) and occupational exposures. In all, 374 cases were reported to the Finnish Cancer Registry in 1979 and 1980. After the exclusion of wrong diagnoses, nonrespondents and cases for whom the primary site was uncertain, 126 cases (64 men and 62 women) remained. Each case was matched for sex, age (+/- 5 years), vital status and geographical district with two cases of coronary infarction selected from hospital records without any knowledge of occupational history. Nonrespondence (38%) reduced the number to 175 referents (82 men and 92 women). A questionnaire on former employment and tasks was mailed to living subjects (6 + 6) and to the next of kin of deceased patients. An industrial hygienist then evaluated the exposure history blindly and, whenever necessary, contacted the workplace or the next of kin for more details. Only exposures commencing 10 years or more before diagnosis were considered. Altogether six female cases but no referent had been exposed to solvents. One had been exposed to chlorinated solvents in dry cleaning and two others had used both carbon tetrachloride and aromatic and aliphatic solvents. Three cases had been exposed to mixtures of aliphatic and aromatic solvents, but not chlorinated hydrocarbons. By contrast, the men did not differ with regard to exposure to solvents. Two cases and five referents were classified as having been exposed to solvent mixtures. The present results are hypothesis generating only, and the excess solvent exposure found for women must be confirmed in other studies before any conclusions can be drawn.

A cohort study on workers exposed to trichloroethylene.

The mortality of 2,117 workers exposed to trichloroethylene sometime between 1963 and 1976 was studied. Their names were collected from the files of one biochemical laboratory performing urinary trichloroacetic acid determinations and from the Occupational Disease Register of Finland. Both the total mortality (SMR 69) and the cancer mortality (SMR 77) were lower than expected. Because of the young age structure and the brief follow-up time the results should be interpreted with caution. They suggest, however, that given as short a latency period as 6 to 13 years, trichloroethylene is not a strong human carcinogen. The present material provides a cohort with defined exposure for further follow-up.