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O Axelson

Publications and source records attributed to O Axelson.

At least 145 records · Page 8Linked to original sources
PubMed1984

On the problem of controlling confounding in case-referent studies.

Individuals in various exposure categories constitute an epidemiological study population and its health experience over time can be taken as the base of the study, which is either open with a turnover of individuals (deaths, migrations etc) or closed, when encompassing only originally defined individuals. In cohort studies all individuals are known in terms of membership and exposure, whereas case-referent (case-control) studies utilize a sample from the base, the referents, for information about the exposed and non-exposed domains of the base, and the referents are a sort of relative denominators for the cases. An association in the base between the exposure and another determinant of the disease means confounding and can be fully accounted for in the cohort approach, but not in the case-referent study as relying on a sample of the base. The reason is that the occurrence of the confounder among the referents is influenced by random variation in the sampling procedure and the referents may therefore not always reflect the true situation with regard to confounding in the base. Computer simulations of the acquisition process of referents illustrate that neither a confounded nor a non-confounded base might always be properly reflected in case-referent data. However, the variation of the confounding rate ratio (the crude rate ratio/SMR) might not be expected to vary by more than about a factor of two. Particularly in nested case-referent studies, a relatively large number of referents helps stabilize the random variation, but only the cohort approach provides full control of confounding, a fact, that becomes the more important, the smaller the effect under study.(ABSTRACT TRUNCATED AT 250 WORDS)

Computers↗
PubMed1983

Solvents and the liver.

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Chemical and Drug Induced Liver Injury↗
PubMed1983

Quantitative aspects of radon daughter exposure and lung cancer in underground miners.

Epidemiological studies have shown an excessive incidence of lung cancer in miners with exposure to radon daughters. The various risk estimates have ranged from six to 47 excess cases per 10(6) person years and working level month, but the effect of smoking has not been fully evaluated. The present study, among a group of iron ore miners, is an attempt to obtain quantitative information about the risk of lung cancer due to radon and its daughters among smoking and non-smoking miners. The results show a considerable risk for miners to develop lung cancer; even non-smoking miners seem to be at a rather high risk. An additive effect of smoking and exposure to radon daughters is indicated and an estimate of about 30-40 excess cases per 10(6) person years and working level month seems to apply on a life time basis to both smoking and non-smoking miners aged over 50.

Aged↗
PubMed1983

Elucidation of some epidemiologic principles.

This review is an attempt to elucidate some fundamental epidemiologic concepts, particularly various aspects of the case-referent design and its relations to the cohort type of study. Some of these aspects also have direct implications for judgements about the comparability of differently exposed population groups, eg, with regard to confounding.

Epidemiologic Methods↗
PubMed1983

Experiences and concerns on lung cancer and radon daughter exposure in mines and dwellings in Sweden.

A high mortality from lung cancer among miners was reported from Central Europe already in the 19th century. In the 60s and 70s several reports have indicated an increased lung cancer mortality among uranium miners and other metal-miners, e.g. in the US, UK, France and Sweden, but also among fluorspar miners in Canada. The cause is supposed to be the decay products of radon as emanating from the rocks, i.e. the alpha-radiation from short-lived radon daughters. Radon and radon daughter exposure in dwellings have more recently attracted interest as a potential hazard to the general population, especially since radon daughter concentrations seem to have increased due to more effective insulation for energy saving. In many Swedish houses the radon daughter exposures amount to levels similar to that of mines. Some epidemiological evaluations of the relationship between lung cancer and exposure to radon daughters, i.e. residency in stone houses versus wooden houses (with and without consideration of the contribution of radon from the ground underneath the houses), seem to indicate a risk also to the general population and, moreover, the risk of smoking seems to be several times greater in stone houses than in wooden houses, the latter usually having less radon daughters on the average.

Adult↗
PubMed1983

Assessment of methods and results of reproductive occupational epidemiology: spontaneous abortions and malformations in the offspring of working women.

Epidemiological studies relating occupational exposures of working women to spontaneous abortions and malformation are reviewed and some methodological considerations are presented. The reproductive epidemiology is less developed than epidemiology in general and seems to involve some specific problems. The ascertainment of exposure and of outcome may be problematic. The exposures may be reported differently by the women depending on the outcome of the pregnancy; thus confirmation of exposure from an independent data source would be an asset. The recognition of spontaneous abortions by women is variable and this should be considered in the study design. An access to medical records could provide objective data on the outcome, but it may introduce other types of asymmetries. The types of occupational exposures of the women, suggested to carry a risk of spontaneous abortions, include anesthetic agents, laboratory work, copper smelting, soldering, and chemical sterilization using ethylene oxide and glutaraldehyde. Maternal employment in laboratories and exposure to solvents has been linked to a risk of congenital malformations in the offspring in five studies. Data on the teratogenic effects of anesthetic gases has been conflicting. In one study, employment in copper smelting was associated with malformations in the offspring.

Abnormalities, Drug-Induced↗
PubMed1983

Pregnancy outcome among women in a Swedish rubber plant.

Suspicions of reproductive disturbances among women in a tirebuilding department was the reason for this study, encompassing 42 women, 30 of whom provided a total of 84 pregnancies out of which 21 were exposed to the tirebuilding process. Nine of the 21 exposed pregnancies had an unfavorable outcome (threatening abortion, spontaneous abortion or malformation) versus only seven of the remaining 63 nonexposed pregnancies, a difference which remained significant also when various risk indicators like age, smoking, pregnancy order, and calendar year were taken into account. In contrast to earlier observations, there was no difference in thioether excretion in the urine (as potentially indicative of the skin absorption of rubber chemicals) between women working in the tirebuilding department and a reference group. It remains unclear however whether the observed cluster was causally related to occupational exposures or not, but, together with other observations, this report may contribute to the elucidation of possible reproductive disturbances in the rubber industry.

Abnormalities, Drug-Induced↗
PubMed1982

Epidemiological study of nasal and nasopharyngeal cancer and their relation to phenoxy acid or chlorophenol exposure.

Soft tissue sarcoma and malignant lymphoma have been related to exposure to chlorinated phenoxy acids or chlorophenols as well as exposure to organic solvents and malignant lymphoma. However, colon cancer studied by the same case-referent design did not show any such associations, which helps to rule out alleged systematical bias of the study approach. Further considerations about exposure routes for phenoxy acids and chlorophenols suggested that nasal and nasopharyngeal cancers should be studied. Forty-four cases with nasal cancer and 27 cases with nasopharyngeal cancer were eligible for study during 1970-1979 together with 541 referents, as utilized also in the aforementioned studies. Exposure to phenoxy acids gave formally a doubled but insignificant risk for the studied cancer types. Exposure to chlorophenols, as present particularly in woodwork, was related to an about sevenfold and significant increase in the risk for both cancer types. In woodworkers without exposure to chlorophenols there was an approximate normal risk, but cabinet makers, even without exposure to chlorophenols, had nearly doubled (but insignificant) risk of nasal cancer.

Adenocarcinoma↗
PubMed1982

Cancer morbidity among polishers.

The mortality pattern among 86 men was determined to investigate the possible hazards of polishing steel. The men had polished steel with polishing paste for at least five years. The polishing pastes had contained tallow, beeswax, carnauba wax, alundum, carborundum, ferric oxide, and chalk. A total of 18 men had died compared with 13.3 expected. Four had died of stomach cancer compared with 0.44 expected (p less than 0.005). The mortality for other causes of death was not increased. The study does not permit any definite conclusion but indicates a possible cancer hazard among polishers.

Aged↗
PubMed1982

A validation of questionnaire information on occupational exposure and smoking.

Occupational exposure information obtained via a questionnaire to close relatives of 160 deceased smelter workers was compared with data from employee registers. The data from the questionnaire regarding employment at the smelter had a very high validity, ie, a sensitivity of 98% and a specificity of 99%. When an assessment of arsenic exposure was made from information in the questionnaire, the sensitivity was only 40%, but the specificity was over 90%. Data on smoking habits were available from medical files for only 14 of the subjects. For all 14, the information was identical to the data in the questionnaires. It appears that questionnaires may sometimes be of use for exposure assessments in occupational health epidemiology.

Adult↗
PubMed1982

A comment on the reference series with regard to multiple exposure evaluations in a case-referent study.

Case-referent (case-control) studies permit multiple exposures to be considered within the same series of cases and referents (controls) with regard to the etiologic contribution to a certain disease. Specific aspects of validity should be considered however, one being the utilization of an adequate reference series. Should the exposure cause, prevent, or otherwise have a certain relationship to disorders other than the one being studied, individuals with such other disorders cannot be uncritically included in the reference series if obtained from a hospital register, a register of causes of deaths, or some other source of subjects with relations to the individuals' health status. If a general population register is utilized, this problem is avoided since individuals obtained from such a register would adequately reflect the exposure frequency of the source population of the cases. These aspects are well illustrated by a consideration of the use of drugs among cases and, on one hand, referents with some sort of disorder as compared to referents (whether healthy or not) obtained from a population register on the other hand. Studies of industrial exposures seem to be somewhat less sensitive to bias of this type however, since industrial exposures are not primarily disorder-related, whereas drug exposures are.

Adult↗
PubMed1982

Effects of low-dose radiation - a correlation study.

The effects of low-dose radiation have been a matter of controversy over the years, and the epidemiologic results have been conflicting. A couple of recent studies have indicated a possible impact on lung cancer mortality from exposure to indoor levels of radon and radon daughters. In this study, selected mortality rates, ie, lung cancer, pancreatic cancer, breast cancer (females only), leukemia, and multiple myeloma were correlated for the counties of Sweden with estimates of average background radiation exposure in these areas. Significant correlations were obtained for lung cancer (males, r = 0.46; females r = 0.55) and pancreatic cancer (males, r = 0.59; females, r = 0.40) , and there was a borderline correlation (r = 0.36; p = 0.04) for leukemia in males. In all, there were positive correlations for eight out of the nine computations made. Since background radiation correlates with urbanization and therefore with smoking, air pollution, etc, the correlations might be spurious due to confounding; on the other hand confounding is a reciprocal phenomenon which suggests that background radiation should to be taken into consideration when widespread risk factors like smoking, coffee drinking, general air pollution, etc, are studied.

Adult↗