Carl-Göran Ohlson

Occupational exposure to polyvinyl chloride as a risk factor for testicular cancer evaluated in a case-control study.

Occupational exposures were assessed in a case‐control study on testicular cancer using self‐administered questionnaires. In total, answers were obtained for 148 (91%) cases and 315 (87%) controls. Of the cases, 101 had seminoma and 47 had embryonal testicular cancer. An increased odds ratio (OR) was found for exposure to polyvinyl chloride (PVC) yielding an OR of 6.6 (95% confidence interval, 1.4–32). The risk increased further if cases with self‐reported cryptorchidism or orchitis were excluded. Six of the 7 exposed cases had seminoma. Exposure to other types of plastics did not significantly increase the risk of testicular cancer. Int. J. Cancer 73:828–830, 1997.

Nephrotoxicity of uranium in drinking water from private drilled wells.

OBJECTIVES To investigate the association between uranium in drinking water from drilled wells and aspects of kidney function measured by sensitive urine tests. METHODS Three hundred and one of 398 eligible subjects (75.6%) aged 18-74 years with daily drinking water supplies from private drilled wells located in uranium-rich bedrock (exposed group) volunteered to participate along with 153 of 271 local controls (56.4%) who used municipal water. Participants responded to a questionnaire on their water consumption and general health, and provided a morning urine sample and drinking water for analysis. RESULTS The uranium content of well water samples (n=153) varied considerably (range <0.20-470 microg/l, median 6.7 microg/l, 5% >100 microg/l), while uranium levels in all samples of municipal water (n=14) were below the limit of quantification (0.2 microg/l). Urinary levels of uranium were more than eight times higher in exposed subjects than in controls (geometric means 38 and 4.3 ng/l, respectively; p<0.001), but their mean urine lead levels were not significantly different. There was a strong curvilinear correlation between uranium in drinking water and in urine (r2=0.66). Levels of albumin, beta(2)-microglobulin, protein HC as well as kappa and lambda immunoglobulin chains in urine from exposed and controls were similar. The N-acetyl-beta-d-glucosaminidase (NAG) activity was significantly lower in the exposed group vs. controls, possibly secondary to differential storage duration of samples from the two groups. Even in regression models adjusting for gender, age and smoking no association of uranium in water and the kidney function parameters was observed. Using uranium in urine in the entire study group as a marker of exposure, however, a tendency of exposure-related increases of beta(2)-microglobulin, protein HC and kappa chains were noted. This tendency was enhanced after exclusion of subjects with diabetes mellitus from the analysis. CONCLUSIONS Uranium levels in urine were strongly correlated to levels in drinking water from drilled wells. There were no clear signs of nephrotoxicity from uranium in drinking water at levels recorded in this study, but some indications of an effect were observed using uranium in urine as a measure of overall uranium exposure. The clinical relevance of these findings remains unclear.

Testicular cancer and occupational exposure to polyvinyl chloride plastics: A case-control study

Exposure to polyvinyl chloride (PVC) plastics as a risk factor for testicular cancer was investigated. In total, 981 cases who were 20–75 years old and had reported to the Swedish Cancer Registry during 1993–1997 were included. One matched control from the population registry was used. Exposure was assessed by a questionnaire that was supplemented over the phone. Furthermore, an occupational hygienist qualified all exposures. In all, 791 matched pairs completed the questionnaire. Overall exposure to PVC plastics gave the odds ratio (OR)=1.35, 95% confidence interval (CI)=1.06–1.71, increasing with >10 year latency period to OR=1.45, 95% CI=1.06–1.98. No dose‐response relationships were found but rather an inverse relationship with the highest odds ratios in the lowest exposure category. In conclusion, no clear association with testicular cancer and exposure to PVC could be found in our study in contrast to a previous observation.

Quartz and Dust Exposure in Swedish Iron Foundries

Exposure to respirable quartz continues to be a major concern in the Swedish iron foundry industry. Recommendations for reducing the European occupational exposure limit (EU-OEL) to 0.05 mg/m 3 and the corresponding ACGIH® threshold limit value (ACGIH-TLV) to 0.025 mg/m 3 prompted this exposure survey. Occupational exposure to respirable dust and respirable quartz were determined in 11 Swedish iron foundries, representing different sizes of industrial operation and different manufacturing techniques. In total, 436 respirable dust and 435 respirable quartz exposure measurements associated with all job titles were carried out and are presented as time-weighted averages. Our sampling strategy enabled us to evaluate the use of respirators in certain jobs, thus determining actual exposure. In addition, measurements using real-time dust monitors were made for high exposure jobs. For respirable quartz, 23% of all the measurements exceeded the EU-OEL, and 56% exceeded the ACGIH-TLV. The overall geometric mean (GM) for the quartz levels was 0.028 mg/m 3 , ranging from 0.003 to 2.1 mg/m 3 . Fettler and furnace and ladle repair operatives were exposed to the highest levels of both respirable dust (GM = 0.69 and 1.2 mg/m 3 ; range 0.076–31 and 0.25–9.3 mg/m 3 and respirable quartz (GM = 0.041 and 0.052 mg/m 3 ; range 0.004–2.1 and 0.0098–0.83 mg/m 3 . Fettlers often used respirators and their actual quartz exposure was lower (range 0.003–0.21 mg/m 3 , but in some cases it still exceeded the Swedish OEL (0.1 mg/m 3 . For furnace and ladle repair operatives, the actual quartz exposure did not exceed the OEL (range 0.003–0.08 mg/m 3 , but most respirators provided insufficient protection, i.e., factors less than 200. In summary, measurements in Swedish iron foundries revealed high exposures to respirable quartz, in particular for fettlers and furnace and ladle repair workers. The suggested EU-OEL and the ACGIH-TLV were exceeded in, respectively, 23% and 56% of all measurements regardless of the type of foundry. Further work on elimination techniques to reduce quartz concentrations, along with control of personal protection equipment, is essential.

Primary prevention of cardiovascular disease by an occupational health service.

BACKGROUND Worksites are considered to be a key channel for the delivery of interventions to prevent cardiovascular disease. The aim of this study was to evaluate the effect on the blood cholesterol levels of an intervention program offered by an occupational health service. METHODS The intervention group consisted of 95 employees and the reference group consisted of 74 employees, in all, 169 subjects, with a serum cholesterol > or = 5.2 mmol/l. Both groups completed a standardized questionnaire. Occupational health nurses carried out the blood sampling before and after the program. The intervention group was then offered counseling on physical activity and a dietician offered individual counseling on healthy food habits. The reference group was not the subject of the intervention program. RESULTS The mean cholesterol level decreased by 0.3 mmol/l (5%) in the intervention group and for the men the decrease was 0.5 mmol/l, while the mean level of the reference group was unchanged. Furthermore, there was a nonsignificant decrease of the mean triglyceride level in the intervention group. CONCLUSION The results of this controlled trial indicates that risk factors for cardiovascular disease can be reduced by interventions at the worksite. Even modest reductions of cholesterol levels may reduce the risk to a tangible degree.

Inflammatory markers and exposure to occupational air pollutants

Objectives: To study the possible relationship between inhalation of airborne particles in the work environment and inflammatory markers in blood. Methods: Total dust was sampled in the breathing zone of 73 subjects working with welding, cutting, grinding and in foundries such as iron, aluminium, and concrete. Stationary measurements were used to study different size fractions of particles including respirable dust, particulate matter (PM)10 and PM2.5, the particle number concentration, the number of particles deposited in the alveoli, and total particle surface area concentration. Inflammatory markers such as interleukin-6 (IL-6), C-reactive protein (CRP), fibrinogen, d-dimer, and urate were measured in plasma or serum before the first shift after the summer vacation and after the first, second, and fourth shift. Results: The mean level of total dust in the breathing zone was 0.93 mg/m3. The proxies for mean respirable dust fraction was 0.27 mg/m3, PM10 0.60 mg/m3, and PM2.5 was 0.31 mg/m3. The IL-6 values increased by 50% after the first day, but decreased after shift on the second and fourth day. CRP did not increase after the first shift but increased by 17% after the second shift. Other biomarkers were unaffected. A multiple linear regression analysis of a subgroup of 47 subjects showed a statistically significant positive relationship between particle exposure and post-shift IL-6. Conclusion: This study supports previous investigations observing increases of IL-6 at air concentrations of PM10 or PM2.5 between 0.13 and 0.3 mg/m3 among healthy subjects. This increase of IL-6 may indicate an increased risk of coronary heart disease.

Winter weather conditions and myocardial infarctions

The daily number of cases of myocardial infarctions admitted to a hospital in middle Sweden over three winter seasons 1984-87 was correlated to the weather conditions on a day-to-day basis. The study encompassed 634 days and all cases younger than 70 years, living within the catchment area, in all 382 subjects. Information on temperature, wind force, precipitation and atmospheric pressure was obtained from the Swedish Institute of Meteorology and Hydrology. A low number of myocardial infarctions was seen on Saturdays and Sundays with a mild wind chill factor and on days with moderate snowfall and high atmospheric pressure. A high number was observed for workdays, especially Mondays, as day of diagnosis. Heterogeneity of the study population and a misclassification of the time relationships between dates of diagnosis and weather changes may have caused an underestimation of the impact of weather conditions. However, weather conditions do not seem to be a major triggering factor of myocardial infarctions in Sweden.

Exposure assessment and modeling of quartz in Swedish iron foundries for a nested case-control study on lung cancer

Exposure assessment of quartz in Swedish iron foundries was performed based on historical and current measurement data. To evaluate the exposure-response relationship between quartz exposure and lung cancer, we modeled quartz exposure from our database of measurements using determinants job title, time period, and company. Based on these modeled exposure data, we conducted a nested case-control evaluation. In our database, the overall individual, daily time-weighted average (TWA) quartz concentrations of current and historical data varied between 0.0018 and 4.9 mg/m3, averaging 0.083 mg/m3. Job titles with mean TWAs for the whole study period exceeding the European Union recommended occupational exposure limit of 0.05 mg/m3 were fettlers (0.087 mg/m3), furnace and ladle repair (0.42 mg/m3), and maintenance (0.054 mg/m3) workers. The mixed model analysis demonstrated significant determinants on the job level for furnace and ladle repair (β = 4.06; 95% confidence interval [CI] 2.78–5.93). For all jobs, significantly higher exposure levels occurred only during the first time period, 1968–1979 (β = 2.08; 95% CI 1.75–2.47), and a decreasing but not significant trend was noted for the three following 10-year time periods up to 2006 (β = 1.0, 0.96 and 1, respectively). Two iron foundries had significantly higher quartz concentration levels than the others (β = 1.31; 95% CI 1.00–1.71 and β = 1.63; 95% CI 1.00–2.65, respectively). The individual cumulative quartz exposure measures were categorized in low, medium, and high exposure (0.5–<1, 1–1.9 and ≥ 2 mg/m3 *years, respectively). In the nested case-control analysis, we found the highest odds ratios of lung cancer (OR 1.17; 95% CI 0.53–2.55) for the medium exposure group. No dose-response trend or significantly increased risk was determined for our high exposed group (≥2 mg/m3), representing 40 years of exposure at >0.05 mg/m3 of quartz. To conclude, certain foundry workers are still exposed to high levels of quartz, but an increased risk of lung cancer caused by quartz exposure in these Swedish iron foundries could not be confirmed at our exposure levels.

On the Use of Different Measures of Exposure—Experiences from a Case-Control Study on Testicular Cancer and PVC Exposure

Associations between exposure to PVC plastics and testicular cancer have been reported. To improve the exposure-response analysis in a matched case-control study on testicular cancer and occupational exposures, a self-administered exposure questionnaire and expert assessment was applied and different exposure measures were developed. The questionnaires regarding work histories and employment in PVC production, manufacturing, and handling of PVC products were completed by 1582 subjects (90%). By expert assessment, 360 subjects were considered exposed, and the exposure intensity to PVC plastics for different working periods was determined. Different exposure measures to PVC plastics were then developed, such as ever/never exposed, duration, maximum intensity, median intensity, and cumulative median intensity. The correlation between the different measures of exposure was high for exposure duration and the cumulative median exposure intensity (Spearman rank coefficient rs = 0.94), as was the correlation between the maximum intensity and the median intensity (rs = 0.94). The agreement between the answers in the questionnaire and the expert assessments was moderate, Kappa value 0.56. The odds ratio for “ever” exposed based on the exposure as reported in the questionnaire was 1.1 (95%, CI 0.82–1.56), and as determined by expert assessment 1.3 (CI 1.05–1.69). The odds ratios for all four different categories of exposure measures varied between 0.86 and 2.6 but decreased by increasing exposure. An overall excess of testicular cancer for the PVC exposed vs. the unexposed was not supported by the pattern seen in a standard exposure-response analysis based on several exposure measures. The findings stress the importance of using several exposure measures as dose surrogates when the underlying toxic mechanisms are unknown and when there are indications of an overall effect.