Jos J. M. Slangen

Risk of gastric cancer in pneumoconiotic coal miners and the effect of respiratory impairment.

OBJECTIVES--This study was carried out to investigate the mortality patterns in a group of 3790 coal miners. The study population had abnormal chest x ray films at a routine medical examination that was performed in the 1950s. METHODS--The total group of 3790 coal miners were followed up for mortality up to 1 January 1992. Causes of death, determined and coded at time of death, were traced with help from the Central Bureau of Statistics. RESULTS--Total mortality in this group of coal miners with abnormal chest x ray films was significantly higher than expected (SMR 127.1, 95% CI 122.5-131.6), mainly a reflection of the increase in mortality from non-malignant respiratory disease (SMR 411.0, 95% CI 382.3-441.3). Mortality from gastric cancer was also significantly increased (SMR 147.5, 95% CI 122.3-176.3). This risk of mortality from gastric cancer was confined to workers with no pneumoconiosis or only a mild form. Despite the strong relation to duration of employment and pneumoconiosis the group of workers with more severe manifestations of pneumoconiosis did not experience an excess in mortality from gastric cancer. CONCLUSION--This study confirms the earlier reported risk of gastric cancer in coal miners. Also it confirms the hypothesis that this risk of gastric cancer is limited to workers with a mild degree of pneumoconiosis or none. In workers with severe forms of pneumoconiosis the pulmonary clearance system is impaired in such a way that the inhaled coal dust does not reach the digestive tract.

Weight Loss is a Reversible Factor in the Prognosis of Chronic Obstructive Pulmonary Disease

The objective of the study was to further unravel the prognostic significance of body weight changes in patients with COPD. Two survival analyses were performed: (1) a retrospective study, including 400 patients with COPD none of whom had received nutritional therapy; (2) a post hoc analysis of a prospective study, including 203 patients with COPD who had participated in a randomized placebo-controlled trial. There was no overlap between the patient groups. Baseline characteristics of all patients were collected on admission to a pulmonary rehabilitation center in stable clinical condition. In the prospective randomized placebo-controlled trial, the physiologic effects of nutritional therapy alone (n = 71) or in combination with anabolic steroid treatment (n = 67) after 8 wk was studied in patients with COPD prestratified into a depleted group and a nondepleted group. Mortality was assessed as overall mortality. The Cox proportional hazards model was used to quantify the relationship between the baseline variables age, sex, spirometry, arterial blood gases, body mass index (BMI), smoking, and subsequent overall mortality. Additionally, the influence of treatment response on mortality was investigated in the prospective study. The retrospective study revealed that low BMI (p < 0.001), age (p < 0.0001) and low PaO2 (p < 0.05) were significant independent predictors of increased mortality. After stratification of the group into BMI quintiles a threshold value of 25 kg/m2 was identified below which the mortality risk was clearly increased. In the prospective study, weight gain (> 2 kg/8 wk) in depleted and nondepleted patients with COPD, as well as increase in maximal inspiratory mouth pressure during the 8-wk treatment, were significant predictors of survival. On Cox regression analysis weight change entered as a time-dependent covariate remained an independent predictor of mortality in addition to all variables that were entered in the retrospective study. The combined results of the two survival analyses provide evidence to support the hypothesis that body weight has an independent effect on survival in COPD. Moreover the negative effect of low body weight can be reversed by appropriate therapy in some of the patients with COPD.

Mortality of coke plant workers in The Netherlands.

During the production of coke, large quantities of coke oven gas are emitted. People who work on the top or on the sides of coke ovens are exposed to this oven gas, which contains a range of carcinogenic chemicals. To investigate the cancer risks under these work conditions, a retrospective study was undertaken. In total 11,399 former workers were enrolled in the study. Of these, 5639 had worked in the coke plant for at least six months between 1945 and 1969. The other 5740 had worked in another plant during the same period and formed a non-exposed group for comparison. The study group was followed up until 1984 for mortality. The causes of death were obtained from the Central Bureau of Statistics. Among the coke oven workers significantly higher death rates were found for lung cancer and non-malignant respiratory disease. Mortality in the byproduct section was similar to that expected. Among workers in the tar distillery the rate for lung cancer was higher than expected. The risk for gastric cancer and non-malignant respiratory disease among the workers of the coke shipping department was increased but the SMRs did not reach statistical significance. No data were collected about individual smoking habits or socioeconomic state of the study subjects and the possibility that the risk found could be attributed to these factors cannot be ruled out. It has been stated by other investigators, however, that the effect of not controlling for smoking tends to be modest.

Cancer mortality in workers exposed to dieldrin and aldrin: an update.

This study was conducted to investigate the possible long-term health effects, in particular carcinogenic effects, of occupational exposure to the organochlorine insecticides dieldrin and aldrin. We updated an earlier cohort mortality study of 570 employees involved in the production of these insecticides. All of the employees had worked in the production plants between 1 January 1954 and 1 January 1970 and were followed for cause-specific mortality until 1 January 2001. Based on dieldrin levels in blood samples taken during the exposure period, available for 343 workers, individual estimates of the total intake of dieldrin were estimated for all individual subjects in the cohort. The estimated total intake ranged from 11 to 7755 mg of dieldrin, with an average of 737 mg. One hundred and seventy-one workers had died before 1 January 2001, compared with an expected number of 226.6, giving a standardized mortality ratio (SM R) of 75.6 [95% confidence interval (CI): 64.6-87.7]. This deficit in total mortality was mainly attributable to a deficit in cardiovascular disease mortality, but cancer mortality was also lower than expected. The observed number of deaths from rectal cancer was significantly higher than expected (SM R 3/4-300.0; 95% CI: 109.5-649.3), but was most pronounced in the low-intake subgroup and appears to be unrelated to exposure to dieldrin and aldrin. This study reinforces the earlier findings that occupational exposure of workers to significant amounts of dieldrin and aldrin has not led to a higher cancer mortality than would be found in an unexposed population.

Mortality and lung cancer in ceramic workers in the Netherlands: Preliminary results

A retrospective cohort study in 1794 male ceramic workers in the Netherlands was carried out to analyze the lung cancer risk in relation to crystalline silica exposure and silicosis. They had all been employed for two years or longer in ceramic industries between 1972 and 1982. During a health survey, 124 cases of simple pneumoconiosis were diagnosed; after 14 years of follow-up, 161 deaths had occurred. No increased overall and cause-specific mortality was found in the total group of ceramic workers, and a statistically significant cumulative dose-response relation for silica exposure and lung cancer did not emerge. An excess lung cancer mortality appeared among workers with simple pneumoconiosis. The authors conclude that the disease process resulting in silicosis in the ceramic industry carries an increased risk of lung cancer, which is supportive of a nongenotoxic pathway.

The organic solvent syndrome

SummaryA study was conducted to investigate the existence of a “specific” neurotoxic effect due to long-term exposure to organic solvents. A comparison was made regarding diagnoses, symptoms and other relevant medical data between persons receiving a disability pension on the basis of a neuropsychiatric disorder selected from an exposed (painters) and non-exposed (construction workers) trade organization. Information was collected from their medical files at the occupational health department. Concerning diagnoses and symptoms, no significant differences were found between exposed and non-exposed patients. No indications were found for the existence of a “typical” complex of symptoms associated with exposure to organic solvents among painters in The Netherlands. The number of reported symptoms was not related to the duration of exposure, thus lending no support for a dose-effect relationship. If a neurotoxic effect does exist among Dutch painters, it is of a non-specific type and not clearly distinguishable from other mental disorders.

Red Blood Cell Antioxidant Parameters in Healthy Elderly Subjects Versus Silicosis Patients

The anti-oxidant phenotype was determined in red blood cell haemolysates of 62 healthy elderly persons (Mean age: 56) and a number of male silicosis patients (Mean age: 65, n = 19). Moreover, analysis of water-soluble fluorescent substances in plasma, recently introduced as a new test for in vivo lipid-peroxidation, was included. Within the control group results were analyzed on the effect of smoking (no effect), use of medication (lowered GSH-content) or gender (no differences apart from haemoglobin content). No simple relationship between any pair of the measured parameters in erythrocytes was present. When comparing the male control persons with the silicosis group a significantly higher red blood cell GSH-level was observed in the latter. Moreover, some factors of the anti-oxidant system are strongly correlated in the diseased, but not in the healthy subjects.

Trends and geographical patterns of pleural mesotheliomas in the Netherlands 1970-87.

The sex and age related trends and geographical distribution of asbestos related mortality from pleural mesothelioma in the Netherlands between 1970 and 1987 were investigated. Deaths from pleural malignancies recorded by the Dutch Central Bureau of Statistics (CBS) were used and death rates were age adjusted per year by the indirect method. Standardised mortality ratios (SMRs) were computed for 43 regions over the period 1979-86. For men, total mortality increased from 10.8 per million in the period 1970-8 to 20.9 per million during 1979-87. The highest mortality occurred in the group aged between 65 and 74 with 147.7 per million in 1987. The death rate for the group aged between 55 and 64 was 96.5 per million in 1987. For women, total death rates for pleural mesothelioma showed a moderate increase from 2.5 per million in the period 1970-8 to 3.6 per million during 1979-87. The highest mortality occurred in the group aged over 65, fluctuating around 10-15 per million. For men and women under 45 mortality was very low and presented no upward trend. The geographical distribution over the country for the period 1979-86 showed a pattern with a clear concentration of deaths from mesothelioma in men, in conurbations with many harbours, shipyards, and heavy industry near the river mouths and along the North Sea Coast.

Respiratory effects and serum type III procollagen in potato sorters exposed to diatomaceous earth

Exposure to diatomaceous earth with low crystalline silica content (< 1%) is rarely reported to cause pneumoconiotic disease, whereas airway obstruction and bronchitis are more frequently reported. We investigated the occurrence of pneumoconiosis and airflow limitation in 172 male workers from 5 potato sorting plants (55 controls, 29 salesmen, 72 currently exposed, and 16 retired exposed) exposed to inorganic dust from former sea terraces (7.7–15.4 mg/m3), high in diatomaceous earth. The presence of fibrosis was evaluated by chest radiographs (exposed only) and serum levels of type III procollagen (P-III-P) were measured as an estimate of fibrogenetic activity. Lung function was assessed by flow volume curves and impedance measurements. A validated questionnaire was used to record respiratory symptoms. No pneumoconiotic abnormalities were demonstrated by chest radiographs. In line with this finding, serum P-III-P levels were not elevated in exposed workers as compared to controls, suggesting no differences in fibrogenetic activity. In fact, serum P-III-P levels decreased significantly (P < 0.03) with increasing cumulative exposure. Flow volume parameters indicated airflow obstruction, dose-related to (cumulative) dust exposure; the annual decline in forced expiratory flow volume (FEV1) was estimated at 10.5 m1/year (P < 0.05). Airway obstruction was confirmed by impedance analysis: In the retired group impedance changes were compatible with airway obstruction extending into the peripheral airways. We conclude that this exposure to quartz during potato sorting does not result in an increased risk for pneumoconiosis, but that (prolonged) surveillance in this group is desirable in order to detect early indications of airflow obstruction.

Mortality update of workers exposed to acrylonitrile in The Netherlands.

To study the possible carcinogenic effects of acrylonitrile, we updated the follow up of a cohort of 2842 acrylonitrile workers. The comparison group consisted of 3961 workers from a nitrogen fixation plant. Industrial hygiene assessments quantified past exposure to acrylonitrile, 8-hour averages as well as peak exposure, the use of personal protective equipment, and exposure to other potential carcinogenic agents. Standardized mortality ratios were calculated to adjust for the effect of age distribution, length of follow up, and temporal changes in background mortality rates. Cumulative dose-effect relations were determined for 3 exposure categories and 3 latency periods. The results show that no cancer excess seems related to exposure to acrylonitrile. This additional follow up of a cohort of 2842 workers exposed to acrylonitrile further supports the notion that occupational exposures to acrylonitrile that have occurred in the past have not noticeably increased workers’ cancer mortality rates.