Relative risk of mesothelioma associated with different levels of exposure to asbestos.

The relative risk of mesothelioma associated with different levels of exposure to asbestos was evaluated. The exposure was assessed from work histories of 51 mesothelioma cases and 51 sarcoidosis referents. The lung fiber concentration of the mesothelioma patients was compared with that of two reference groups (13 random autopsy cases and 43 male lung cancer patients). When the categories definite and probable were used as an estimated probability of occupational exposure, an odds ratio of 17.7 [90% confidence interval (90% CI) 3.4-253] and 3.0 (90% CI 0.9-10.6), respectively, was obtained. A lung fiber concentration of greater than 1 million fibers/g of dry tissue as an indicator of accumulated exposure gave an odds ratio of 14.4 (90% CI 2.5-178) for the men in comparison with the autopsy cases and 3.1 (90% CI, 1.3-7.5) in comparison with the lung cancer patients. Elevated risk of mesothelioma was shown to be associated with a lung fiber concentration of greater than 1 million fibers/g of dry tissue.

Occupational exposure to asbestos as evaluated from work histories and analysis of lung tissues from patients with mesothelioma.

The past occupational exposure to asbestos of 23 patients with mesothelioma (21 men and two women) has been evaluated by a personal interview of their work history and by determination of the fibre burden in their lung tissue with scanning electron microscopy (SEM) and x ray microanalysis. According to the work history, nine patients (39%) had definitely been or probably been exposed to asbestos, six patients (26%) had had possible exposures, and eight patients (35%) unlikely or unknown exposure to asbestos. The two female patients were in the unknown exposure category. The fibre concentrations in the patients' lung tissue ranged from less than 0.1 million to 370 million fibres (f) per g dry tissue. Concentrations of over one million f per g dry tissue were found in 15 patients (65%). The lung fibre concentrations of all nine male office workers analysed for reference were less than one million f per g dry tissue. Seventy eight per cent of the patients with mesothelioma had at least possible exposure according to their history of work or concentrations of more than one million f per g dry tissue.

Urinary and plasma concentrations of nickel as indicators of exposure to nickel in an electroplating shop.

The relationship between atmospheric exposure to nickel and urine and plasma nickel concentrations was studied by following four workers from an electroplating shop for one work week by daily measurements of the nickel concentration in workroom air with personal samplers and nickel concentrations in blood and urine samples collected before and after the work shift. The workroom air concentrations ranged from 0.03 to 0.16 mg/m3. The urinary and plasma nickel concentrations were higher in the samples taken after than before the work shift and a close positive correlation was found between the air nickel concentrations and the urine and plasma nickel concentrations, respectively. There was also a close correlation between urinary and plasma nickel concentrations. A slight accumulation of nickel occurred as judged from the increasing concentrations of nickel in the urine and plasma morning samples during the study week. This study indicates that both plasma and urine nickel concentrations may be used as biological indicators of exposure to soluble nickel compounds.

Urinary chromium as an indicator of the exposure of welders to chromium.

Five welders working with high alloy Cr-Ni steel and one working with mild steel were followed during one work week. The chromium concentration in air was measured concomitantly with urinary chromium determinations. The water-soluble chromium concentrations in air exceeded 0.05 mg/m3 during welding with coated electrodes, but metal inert-gas (MIG) welding produced much lower concentrations. The proportion of water-soluble hexavalent chromium in the air was usually more than 50% of the total chromium concentration during welding with coated electrodes, whereas less than 10% of the chromium produced during MIG welding was in a water-soluble. Since water-soluble chromium (hexavalent) is the more important biologically, the determination of both water-soluble and water-insoluble chromium concentrations is emphasized instead of the measurement of the total concentration. The urinary chromium concentration proved to be a good indicator of short-term exposure to water-soluble chromium when exposure was above the current threshold limit value of 0.05 mg/m3, concentrations of more than 30 microgram/g of creatinine representing an exposure level higher than the threshold limit value.

Carbon monoxide in foundry air.

The concentration of carbon monoxide in the air of 67 iron, steel, or copper alloy foundries using sand molding was measured. About 1,100 carbon monoxide determinations were made. High concentrations of carbon monoxide were found in the area around the cupolas and the casting sites in iron foundries. The blood carboxyhemoglobin levels of 145 workers from iron foundries were measured. The carboxyhemoglobin level of 6% was exceeded in 26% of the nonsmokers and in 71% of the smokers.

Gases formed from furan binding agents.

Furfuryl alcohol and formaldehyde concentrations in the air of coremaking areas of 10 iron and steel foundries were measured. The mean concentration of furfuryl alcohol and formaldehyde was 4.3 cm3/m3 and 2.7 cm3/m3, respectively. Furfuryl alcohol exceeded its threshold limit value (TLV) of 5 cm3/m3 in 22% of the determinations; and formaldehyde (TLV=2 cm3/m3) in 38%. In addition phenol concentration was determined in one foundry; and phosphoric acid concentration, in two foundries. The concentrations of phenol and phosphoric acid were far lower than their TLVs. The question is raised as to whether exposure to furfuryl alcohol and formaldehyde in foundries in combination with exposure to dust and smoking can increase the risk of chronic bronchitis.