OBJECTIVES: The possibility of an association between exposure to silica and autoimmune diseases has recently come under discussion. In the following case-referent study, a cohort exposed to diatomaceous earth and cristobalite provided an opportunity to evaluate such an exposure with reference to sarcoidosis. METHODS: The inhabitants of a district served by a single healthcare centre and a hospital formed the study base. A diatomaceous earth plant is located in this community and the medical institutions are responsible for primary and secondary health care of the population. Cases of sarcoidosis were identified from the hospital records according to certain clinical, radiological, and histological criteria. Referents were selected randomly from the population of the district. Information on exposure to crystalline silica, cristobalite, was obtained by record linkage of the cases and referents with a file which included all present and past workers at the diatomaceous earth plant and those who had worked at loading vessels with the product from the plant. RESULTS: Eight cases of sarcoidosis were found, six of which were in the exposed group. Of the 70 referents, 13 were exposed. The odds ratio (95% confidence interval) was 13.2 (2.0 to 140.9). CONCLUSION: The odds ratios were high and there were some indications of a dose-response relation which will hopefully encourage further studies. To our knowledge this is the first study to indicate a relation between sarcoidosis and exposure to the crystalline silica, cristobalite.
AIMS: To investigate whether length of employment as a cabin attendant was related to breast cancer risk, when adjusted for reproductive factors. METHODS: Age matched case-control study nested in a cohort of cabin attendants. The cases were found from a nationwide cancer registry (followed up to end of year 2000) and the reproductive factors (age at first childbirth and number of children) from a registry of childbirth, in both instances by record linkage with the cabin attendants' identification numbers. The employment time of the cabin attendants at the airline companies and the reproductive factors had been systematically recorded prior to the diagnosis of breast cancer in the cohort. A total of 35 breast cancer cases and 140 age matched controls selected from a cohort of 1532 female cabin attendants were included in the study. RESULTS: The matched odds ratio from conditional logistic regression of breast cancer risk among cases and controls of cabin attendants was 5.24 (95% CI 1.58 to 17.38) for those who had five or more years of employment before 1971 compared with those with less than five years of employment before 1971, adjusted for age at first childbirth and length of employment from 1971 or later. CONCLUSIONS: The association between length of employment and risk of breast cancer, adjusted for reproductive factors, indicates that occupational factors may be an important cause of breast cancer among cabin attendants; the association is compatible with a long induction period.
Comment In: Occup Environ Med. 2003 Nov;60(11):805-614573708
We investigated cancer incidence during the period 1970-1992 among unskilled Icelandic female workers who contributed to two pension funds for manual workers. We found an increase in the standardized rate ratios (SRRs) for all cancer with increasing time before the follow-up period began. We found no clear relation between cancer incidence and length of employment. The SRRs were higher for those who became members of the funds in 1977 or later than for those who started earlier: among these women, we found SRRs for all cancers, 1.36; cancer of the stomach, 1.49; cancer of the lung, 1.48; cancer of the cervix, 3.19; and cancer of the bladder, 6.00.
The purpose of the present study was to describe the cancer pattern in a cohort of farmers in Iceland and to compare their cancer incidence to that of other Icelandic males. This is a retrospective cohort study. The study population was obtained from a register at the Farmers' Pension Fund and comprised 5922 men. Viewed as a whole the cohort shows a significant lower incidence for all tumours than expected. The same is true of SIR for cancer of colon, lung, prostate, bladder and other urinary organs with SIR of 47, 41, 71 and 51, respectively. However, some etiologic factors may contribute to the increased risk of some cancer sites among farmers. There was an excess for Hodgkin's disease SIR 251, and for cancer of lips, skin (excl. melanomas), nervous system, non-Hodgkin's lymphoma and leukemia with SIR of 183, 150, 128, 142 and 151, respectively, however not statistically significant. The authors suggest that something in farmers lifestyle protects them from various kinds of cancer.
This study investigated cancer incidence among Icelandic nurses, with a special focus on breast cancer. Cancer incidence in the study group was compared with that of the general female population. Elevated standardized incidence ratios (SIRs) were seen for some cancer sites, including breast cancer. For all cancers, breast cancer, and selected cancer sites, SIR increased with increasing length of time intervals allowed to elapse before the study period began. The nurses with a shorter employment time had a higher incidence of cancer than those with a longer one. Known confounding factors--parity and age at first birth--do not appear to be a convincing explanation of the excess of breast cancer. The possibility cannot be excluded that the nursing occupation constitutes an independent risk factor for breast cancer.
BACKGROUND: This study was done to examine the cancer risk among pesticide users in Iceland. METHODS: We have followed a cohort of 2449 licensed pesticide users, students from a horticultural college, members of a pension fund for market gardeners, horticulturists and vegetable farmers up until the end of 1993 in the Icelandic Cancer Registry of cancer incidence. The observed number of cancers was compared with expected values calculated on the basis of cancer incidence for males and females in Iceland. RESULTS: The standardized incidence ratio (SIR) for all cancer sites was 0.80. Among females the increased incidence for cancer of lymphatic and haematopoietic tissue was significant (SIR = 5.56, 95% confidence interval (CI) 1.12-16.23). The incidence of rectal cancer was three times that expected (SIR = 2.94, 95% CI: 1.07-6.40), and this cancer was even more predominant among the licensed pesticides users (SIR = 4.63, 95% CI: 1.49-10.80). All cancers of the rectum were adenocarcinoma, however, one was adenocarcinoma in villous adenoma and one adenocarcinoma in tubulo-villous adenoma. CONCLUSION: The results provide some support for the suggestion that pesticide exposure may lead to cancer of the lymphatic and haematopoietic tissue in females. We suggest that some of the pesticides to which the licensed pesticide users were exposed may lead to rectal cancer.
The cancer incidence was investigated among 27,884 fishermen and sailors from the merchant fleet who had been members of a pension fund for seamen during 1958-1986 in Iceland. The cancer incidence was followed through 1966-1988. Expected values were based on rates for the general male population in Iceland. In the whole cohort, 758 malignant neoplasms had occurred as compared to 688.43 expected, standardized incidence ratio (SIR) = 1.10, 95% confidence limit (CI) 1.03-1.18. There was an excess for cancer of the stomach, rectum, larynx, and lung and nonmelanoma skin cancer; the SIRs were 1.29, 1.44, 1.77, 1.61, and 1.51, respectively. When analyzing the cancer incidence according to length of employment, the SIRs for many of the cancer sites were high for those with a short employment and many SIRs decreased with increasing length of employment. The SIRs for lung cancer were high in all subgroups. Only for stomach cancer and leukemia was there a substantial increase in SIR with increasing length of employment. The SIR was 1.55 for stomach cancer (CI 1.01-2.27) in the group with longer than 10 years of employment, and 1.97 for leukemia (CI 0.85-3.87) in the same group. It is concluded that the risk of both stomach and lung cancer seems to be associated with the occupation of seamen.
A retrospective study is accomplished in Iceland to study whether mortality and cancer incidence among male physicians (1,210) were lower than those among men of the general population and lawyers (1,032). Overall mortality among lawyers was similar to that of the general male population, however, mortality among the physicians was lower than that of the general population and the lawyers, due to lower mortality for all cancers (SMR 0.73), cerebrovascular diseases (SMR 0.53) and respiratory diseases (SMR 0.54). The physicians had higher mortality for suicide committed by drugs, solid or liquid substances. Cancer was not as frequent among the physicians as among the lawyers, particularly for lung cancer, the SIR was 0.45, but the rates were higher for cancer of the colon and brain among the physicians than among others.
PURPOSE: To determine the cause-specific mortality relative to that expected in a population-based incidence cohort of people with unprovoked seizures. METHODS: The cohort comprises 224 inhabitants of Iceland first diagnosed as suffering from unprovoked seizures during a 5-year period from 1960 to 1964. The expected number of deaths was calculated by multiplying person-years of observation within 5-year age categories for each year from diagnosis through 1995 by cause-specific and sex-specific national death rates for those aged 20 years and above. The standardized mortality ratio (SMR) and 95% confidence intervals (95% CI) were calculated. RESULTS: All-cause mortality was increased among men (SMR 2.25, 95% CI 1.56-3.14) but not women (SMR 0.79, 95% CI 0.38-1.46). Among men, there were 8 deaths from accidents, poisoning and violence observed versus 2.82 expected (SMR 2.84, 95% CI 1.22-5.59) and 4 deaths from suicide versus 0.69 expected (SMR 5.80, 95% CI 1.56-14.84). All-cause mortality for men was still elevated after restriction of analysis to those with seizures of unknown etiology (SMR 1.73, 95% CI 1.05-2.67) with the excess deaths attributable to suicide (SMR 5.26, 95% CI 1.06-15.38). Both males and females with remote symptomatic unprovoked seizures had an increase in all-cause mortality due to excess mortality from all cancers, cerebrovascular disease and accidents. CONCLUSION: When compared with the age-, time-period- and gender-specific mortality in the general population, there is excess mortality in men but not women. The increased mortality for men is partly attributable to excess mortality from accidents and suicides.
In a prospective study of a population sample of women, the erythrocyte sedimentation rate (ESR) was studied in relation to the incidence of myocardial infarction, angina pectoris, stroke and intermittent claudication. ESR could not be proved to be predictive of these manifestations of cardiovascular disease. Similar results were obtained when the population was studied cross-sectionally. The ESR was higher in women with hyperlipidaemia (serum triglyceride greater than or equal to 2.0 mmol/l or serum cholesterol greater than or equal to 9 mmol/l), in women with arterial hypertension (treated or untreated, with systolic blood pressure greater than or equal to 160 mm Hg or diastolic blood pressure greater than 95 mm Hg or both) and in overweight women (women within the upper 10 centiles of weight index) compared to women of the same age in the population sample who did not fulfill the criteria according to the above definitions. ESR was similar in hyperuricaemic women (upper 5 centiles of serum uric acid) and in those who were not hyperuricaemic. No association was found between smoking habits and ESR. Weak correlations were found between ESR and serum triglycerides, serum cholesterol and serum uric acid, respectively. Although some correlations were found, ESR cannot replace other examinations in the search for risk factors for cardiovascular disease.