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Biomedical subjects

S Langård

Publications and source records attributed to S Langård.

At least 37 records · Page 2Linked to original sources
PubMed1993

Urinary mercury excretion in chloralkali workers after the cessation of exposure.

Seventeen former chloralkali workers were followed through the regular determination of urinary mercury for nearly two years after the cessation of exposure to mercury vapor in a study of the time course of urinary mercury elimination. Their duration of exposure ranged from 3 d to 35.5 years. A one-compartment model for urinary mercury elimination was applied. The urinary mercury concentration declined at a rate indicating a half-time of 91 d. When corrected for an individual base-line level of urinary mercury resulting from sources of mercury intake not related to work, the half-time was 72.4 [95% confidence interval (95% CI) 63.2-81.7] d, with a mean elimination rate constant of 0.011 (95% CI 0.008-0.013).d-1. The day-to-day variability of the urinary mercury concentration averaged 22%, expressed as the coefficient of variation between urine samples delivered on three consecutive days.

Adolescent↗
PubMed1993

Role of chemical species and exposure characteristics in cancer among persons occupationally exposed to chromium compounds.

Epidemiologic studies on chromate workers are considered with special reference to the valency of chromium compounds, carcinogenic potency, and water solubility. It is assumed that all hexavalent chromium compounds are carcinogenic to humans when inhaled but that there is no evidence that trivalent compounds are carcinogenic. It is suggested that zinc chromate is a highly potent carcinogen and also that calcium chromate may be carcinogenic. There are indications that chromates of low water solubility may be less potent carcinogens than compounds of greater solubility. Evidence is also presented for possible interactions with smoking and other factors involved in work-related cancers.

Adult↗
PubMed1992

[Exposure to asbestos and asbestos-related pulmonary changes among employees at a magnesium plant].

Prevalence of disease related to previous exposure to asbestos was investigated in a cohort of 394 men who had worked for more than a year at a magnesium plant before 1970. Radiography showed lung fibrosis in nine men (2.3%) and pleural plaques in 40 men (9.5%). Prevalence rates varied considerably between sub-groups subjected to different modes of exposure. For the whole cohort there was a positive correlation between prevalence rate of radiographic changes and duration of work entailing exposure to asbestos. Subjects with pleural changes had more dyspnoea than found in an external reference material. Vital capacity and forced expiratory volume in one second was significantly reduced for the whole cohort. A significant reduction in lung function was found among a larger proportion of subjects with pleural changes than among subjects with no radiographic indications of such changes. The results unveil a need for similar surveys among workers in other energy-intensive industries where a similar mode of exposure to asbestos may be assumed.

Adult↗
PubMed1992

Chest radiographs in subjects with asbestos-related abnormalities: comparison between ILO categorizations and clinical reading.

The findings of a previous chest X-ray screening, determined without using standardized criteria, were reassessed by means of the ILO classification. Of 470 radiographs that had been determined as showing asbestos-related changes, 430 were categorized according to the ILO Classification. Small opacities with profusion greater than or equal to 1/0 were described in 39 (52%) of 75 participants who, on the original clinical reading, had been determined as having lung fibrosis, and in 45 (12.7%) of 355 who were determined as having pleural changes only. When considering circumscribed pleural thickening at the chest wall or diaphragm, as categorized by the ILO Classification, such changes were present in 401 (93.7%) of 428 subjects with pleural changes as determined on the clinical reading. In addition to the improved sensitivity and specificity achieved, the ILO Classification also allows comparison with other studies. The most apparent disadvantage of the ILO system is that it cannot firmly separate the various types of asbestos-related pleural changes. The study revealed that the previous asbestos exposure of the case subjects had occurred in many different workplaces and occupations.

Adult↗
PubMed1992

Enhanced cytogenetic detection of previous in vivo exposure to mutagens in human lymphocytes after treatment with inhibitors of DNA synthesis and DNA repair in vitro.

To increase the sensitivity of cytogenetic surveillance of exposure to mutagens in the peripheral lymphocyte assay, structural chromosome aberrations (CA) were studied after inhibition of DNA synthesis and DNA repair with hydroxyurea and caffeine in culture 3 h prior to harvesting. CA and sister-chromatid exchanges (SCE) from conventional cultures from the same subjects were used for comparison. Smoking was used as exposure parameter. Thirty-two smokers and 35 nonsmokers were studied. In the inhibited cultures a significantly higher number of aberrations was found in lymphocytes from smokers than nonsmokers: chromatid breaks (20.4 vs. 11.8, p = 0.0002), chromosome breaks (4.5 vs. 1.7, p = 0.0003), and the number of cells with aberrations (18.9 vs. 12.4, p = 0.0001), when 50 cells per subject were analyzed. In conventional cultures no increase in gaps, chromatid and chromosome breaks or number of cells with aberrations was found in smokers when 100 cells from each subject were studied. Smokers showed an increased number of SCE (6.8 vs. nonsmokers 5.9, p = 0.02). A significant positive linear correlation (r = 0.39, p = 0.01) was seen between SCE and the number of cells with chromatid breaks from inhibited cultures. The present results indicate that adding hydroxyurea and caffeine to lymphocyte cultures for the last 3 h prior to harvesting may enhance the detection of cytogenetic damage from previous in vivo exposure to mutagens.

Adult↗
PubMed1992

Discrimination of smoking status by thiocyanate and cotinine in serum, and carbon monoxide in expired air.

To develop a procedure for maximizing the discrimination of smoking status, the authors analysed parallel samples of thiocyanate and cotinine in serum, and carbon monoxide (CO) in expired air in a cohort of 145 male subjects aged 45-65 years. The sensitivity and specificity were 93% and 82%, 97% and 83%, and 98% and 100% for thiocyanate, cotinine, and CO respectively. The results were not significantly improved when combining two or three methods as compared with CO separately. Also, cotinine in urine was analysed in a subgroup of 21 subjects. The correlation coefficient between cotinine in serum and urine was 0.92. In a subgroup of 44 subjects with extensive information on smoking habits, CO was the only indicator significantly related to the quantity of tobacco smoked. We conclude that CO seems sufficient for validating smoking status, but as atypical smokers who are vulnerable to misclassification may be overrepresented in smoking cessation programmes, combining two methods could still be useful. Validating the amount of tobacco smoked is of limited use with the current methods.

Aged↗
PubMed1992

Proposal for future uses in epidemiology for cohort studies on the prevention of work-related cancer.

A new use of the cohort method in cancer prevention is proposed involving individual collection of information on past exposure to dominating cancer determinants. It is assumed that it is possible to determine individual cancer risk and, subsequently, to estimate the individual risks of cause-specific cancers on the basis of accurate individual data on exposure to cancer determinants. Individuals at given risk levels should subsequently be assigned to defined risk categories to establish groups designed for risk-determined screening programs and risk-determined information intervention. As increased risk to work-related cancer is generally more strongly related to past than to current exposure, a large proportion of those who are at high risk are no longer employed and thus not in reach of occupational health physicians. Therefore, risk-determined intervention should be integrated into the daily work routines of both occupational health physicians and primary care physicians.

Cohort Studies↗
PubMed1991

[Accomplishment of health promotion in municipalities].

Currently, the gap between the demand for treatment of cases of illness and the available resources for curative medicine has become so wide in Norway that it is time to introduce a new comprehensive system for preventive medicine in order to reduce human suffering and the cost of curative medicine. The authors propose a new system of preventive medicine which involves systematic collection of personal data on disease determinants, and concentrated intervention directed at individuals at high risk of illness and accident. Implementing a new system of prevention requires the establishment of units for intervention and screening, one unit per 100,000 to 300,000 persons. These units should collect personalized data on exposure to risk, particularly among high risk groups, to enable screening of groups of subjects according to their exposure to disease determinants and subsequent a priori disease risks. Based on systematic collection of such data, individualized risk-determined intervention is proposed among identified risk groups, to be carried out within the existing primary health care system.

Health Promotion↗
PubMed1991

Cancer incidence among asbestos-exposed chemical industry workers: an extended observation period.

A previous study on the incidence of cancer in a cohort of 286 asbestos-exposed electrochemical industry workers observed from 1953 through 1980 has been extended with another 8 years of follow-up. The incidence of cancer was derived from the Cancer Registry of Norway, and the expected figures were calculated by a life table method. During the extended follow-up period from 1981 through 1988, among the cohort members there were 12 new cancer cases versus 14.2 expected (SIR 85, 95% CI 44-158). In a lightly exposed sub-cohort, the extended follow-up revealed 4 cases of lung cancer or pleural mesothelioma (ICD, 7th revision 162-163) versus 1.6 cases expected (SIR 256, 95% CI71-654). In a heavily exposed sub-cohort, the corresponding figures were 3 and 0.5 (SIR 588, 95% CI 118-1,725).

Asbestos↗
PubMed1991

A collaborative study of cancer incidence and mortality among vinyl chloride workers.

A large European multicentric cohort study has been coordinated by the International Agency for Research on Cancer with the objectives of investigating the dose-response relationship between liver cancer and exposure to vinyl chloride and assessing cancer risk for sites other than the liver. A nearly threefold increase in liver cancer was detected on the basis of 24 observed deaths and 8.4 expected (standardized mortality ratio 286, 95% confidence interval 186-425). The excess from liver cancer was clearly related to time since first exposure, duration of employment, and estimated ranked and quantitative exposures. Other cancer sites investigated on the basis of a priori hypotheses were either not in excess (lung) or apparently unrelated to the exposure variables (brain and lymphoma).

Adult↗
PubMed1990

One hundred years of chromium and cancer: a review of epidemiological evidence and selected case reports.

The present review is motivated by the fact that 100 years have passed since the first cancer case in a chromium worker was reported in Scotland. Old and recent case reports and epidemiological studies among chromate workers are reviewed to elucidate the importance of valency states and water solubility of chromium compounds for carcinogenic potency. It is concluded that all chromium[VI] compounds should be considered carcinogenic among exposed populations, and that no evidence has been presented indicating that human exposure to chromium[III] is associated with increased cancer risk. Strong evidence has been presented that zinc chromate is a potent carcinogen and suggests that calcium chromate may be a potent carcinogen. Evidence also suggests that water-soluble chromates in general may be more potent carcinogens than those with low solubility. Primary and secondary prevention of chromate-related cancer and the success in preventive measures are briefly discussed, and recommendations for future research are made.

Chromates↗
PubMed1990

Incidence of cancer among ferrochromium and ferrosilicon workers: an extended observation period.

Results are presented of a cohort study on the incidence of cancers and crude death rates in ferrochromium and ferrosilicon workers. The whole cohort was observed from 1 January 1953 to 31 December 1985. Two sets of results are presented; one restricted to workers first employed before 1960 and one to workers first employed before 1965. The latter cohort consists of 1235 workers. The total mortality in the whole cohort was low (SMR = 81) as was the overall incidence of cancers (SIR = 84). There was an overall deficit of deaths and cases of cancer in the ferrosilicon group. An excess of lung cancer (SIR = 154) and cancer of the prostate (SIR = 151) was observed in the ferrochromium workers employed before 1965. Cancer of the kidney was also in excess (SIR = 273) in the ferrochromium group, with a mean "latency time" of 39 years. Two cases of malignant melanomas had occurred versus 0.19 expected in a small subgroup of workers in electrical shops and an electric power station.

Chromium↗
PubMed1989

Characterization of the morphological properties of welding fume particles by transmission electron microscopy and digital image analysis.

The morphological characteristics of welding fume particles have been determined using transmission electron microscopy (TEM) and automatic image analysis (AIA). Two personal samples and one background sample were collected using a new, easy to handle sampling method, during tungsten inert gas (TIG) and manual metal arc (MMA) welding on Inconel in the same shop. The collection method gave samples which were suitable for TEM and AIA. Electron micrographs were taken in a transmission electron microscope and further analyzed using an image analysis unit. Aggregates composed of many individual particles were analyzed both for the parameters of the aggregate and for the parameters of the individual particles by using an algorithm based on a grain boundary reconstruction technique. The morphological parameters allowed the welding fume's particulate matter to be divided into three types - here called small, medium, and large - with a somewhat unclear distinction between medium and large. Medium and large particles occur either as individual particles or as clusters of approximately spherical particles with average diameters of 0.07 and 0.15 microm, respectively. Small particles occur almost exclusively as long chains or lace-like structures of aggregates of particles, often in the range of 5-10 microm. The aggregates have an average projected area of 2.6 x 10-3 microm2 and are composed of several hundred individual particles.

Air Pollutants↗
PubMed1989

Incidence of cancer in a cohort of magnesium production workers.

The results from a cohort study on the incidence of cancer and the mortality in a cohort of 2391 male workers producing magnesium metal are presented. The study population was restricted to employees with more than one year of work experience in the study plant between 1951 and 1974 and the cohort was observed from 1953 to 1984. Altogether 152 new cases of cancer were observed versus 132.6 expected. Six cases of cancer of the lip were found against 2.3 expected, 21 of stomach cancer against 12.8 expected, and 32 of lung cancer against 18.2 expected. A possible causal relation between exposure to factors in the work environment and the development of cancer is discussed.

Chemical Industry↗
PubMed1989

Incidence of cancer among welders and other workers in a Norwegian shipyard.

The incidence of cancer among 4778 male shipyard workers, including 783 mild steel welders, was investigated in a historical cohort study. The workers had been employed for at least three months between 1 January 1946 and 31 March 1977. The incidence of cancer was observed from 1 January 1953 through 1986. The loss during follow-up was only 0.9%. There were 53 observed cases of lung cancer in the whole cohort versus 31.3 expected on the basis of the national rates for men. There was an increased incidence of lung cancer among the welders, with seven observed cases versus 3.2 expected. Twenty-two cases of bladder cancer were observed versus 15.2 expected. Two malignant mesotheliomas had occurred (0.7 expected). Smoking was likely to be a confounder in the present study. Due to concomitant exposure to asbestos, the results are inconclusive concerning the possible relationship between exposure to welding fumes and lung cancer.

Air Pollutants, Occupational↗
PubMed1988

Chromium carcinogenicity; a review of experimental animal data.

Since 1932 exposure to various hexavalent chromium compounds has been known to constitute a cancer hazard to industrial workers. A number of animal studies have been performed and chromates have been administered by inhalation, intratracheally, by intravenous and subcutaneous injection, intraperitoneally and orally. The human epidemiological studies have provided convincing evidence that zinc chromate is a potent carcinogen and there is some evidence that calcium chromate and chromium trioxide also constitute a cancer hazard in humans. The human studies have not selectively confirmed carcinogenic potency for other chromium compounds. The animal studies confirm the carcinogenic potency of calcium chromate and zinc potassium chromate and present strong evidence that chromates of lead and strontium are carcinogenic in animals. The significance of the water solubility for the carcinogenic potency of the chromates has not been clarified by animal studies.

Animals↗