Juha Laitinen

Laboratory and Field Testing of Particle Size-Selective Sampling Methods for Mineral Dusts

The performances of eight sampling devices were tested with mineral dusts in the laboratory and in a talc production plant. The IOM sampler was chosen as the reference method for inhalable dust, and the IOM samplers provided with the porous plastic foam media were used as the reference methods for both the thoracic and respirable aerosols. The other size-selective instruments tested included the Respicon virtual impactor, the optical GRIMM aerosol monitor, and a two-stage cascade impactor with cut points of 10 and 4 microm. The 37-mm cassettes were also included both as open- and closed-face versions. The study confirmed the usability of the IOM samplers for mineral dust, not only in its original version for the inhalable fraction but also its modified versions for the thoracic and respirable fractions. A high correlation with the two-stage impactor results is an indication of good reproducibility. The results increased the evidence that the 37-mm cassette is a poor indicator of inhalable aerosol. The concentrations obtained with both cassette methods were not only systematically too low but also showed large collection efficiency variability. Therefore, the results cannot be corrected by using correction factors. The concentrations of inhalable aerosol measured with the Respicon were generally low, but its performances for the thoracic and respirable fractions were closer to those for the reference samplers. The results also indicate that the GRIMM monitor is well-suited for such mineral dust determinations when very good accuracy is not required, but the immediate availability of the result is more important.

Laboratory and Field Testing of Sampling Methods for Inhalable and Respirable Dust

The performance of four sampling devices for inhalable dust and three devices for respirable dust was tested with different kinds of dusts in the laboratory and in the field. The IOM sampler was chosen as the reference method for inhalable dust, and the IOM sampler provided with the porous plastic foam media was used as the reference method for respirable dust. The other tested instruments were the Button sampler, the optical Grimm aerosol monitor, and the Dekati two-stage cascade impactor with cutoff sizes of 10 and 4 μ m. The study confirmed the applicability of the IOM and Button samplers. The new foam product followed the respirable criteria well. However, the foam sampler was unstable for measuring inhalable dust, probably due to its moisture absorption. In addition, high dust loads should be avoided with the foam sampler due to increase in filtering efficiency. The concentrations of inhalable dust measured with the Button sampler, the Grimm monitor, and the impactor sampler were usually close to those measured with the reference sampler. On the other hand, impactor sampling yielded higher respirable dust concentrations than the reference method in the field, which may have been caused by particle bounce; high dust loads should be avoided while using the impactor. The results also showed that the Grimm monitor enables real-time dust concentration determinations that are accurate enough for routine monitoring of occupational exposure and for testing efficiency of control measures in workplaces.

Kinetics and renal effects of formic acid in occupationally exposed farmers.

Twelve male farmers (38 ± 14 years of age, mean ± SD) were exposed to 7.3 ± 2.2 mg formic acid/m3 for 8 h in the silage making (mean ± SD,N=12). Each gave urine samples immediately, 15 h and 30 h after the end of the exposure. The excretion of formate was linearly related to the exposure 15 and 30 h after the exposure. Exposure increased renal ammoniagenesis and urinary calcium at 30 h post-exposure. Both biochemical effects may be explained by the interaction of formic acid with the oxidative metabolism of renal tubular cells, as formic acid is a known inhibitor of the cytochrome oxidase. In view of these renal effects, the current hygienic limits may not entirely protect exposed individuals.

The Suitability of the IOM Foam Sampler for Bioaerosol Sampling in Occupational Environments

Concurrent samples were collected with Andersen and IOM foam samplers to determine whether if the IOM foam sampler can be applied to collect culturable microorganisms. Two different kinds of aerosols were studied: peat dust in a power plant and mist from coolant fluid aerosolized during grinding of blades and rollers in a paper mill. In the power plant, the concentrations of fungi were 2–3 times higher in the IOM samples than in the Andersen samples. However, more fungal genera were identified in the latter case. The methods yielded similar concentrations of bacteria and actinobacteria in the power plant. On the other hand, the performance of the IOM foam sampler was very poor in the paper mill, where stress-sensitive gram-negative bacteria dominated; low concentration of bacteria was detected in only one IOM sample even though the concentration of bacteria often exceeded even the upper detection limit in the Andersen impactor samples. It could be concluded that the IOM foam sampler performs quite well for collecting inhalable fungi and actinobacteria. However, the Andersen sampler provides better information on fungal genera and concentrations of gram-negative bacteria. Personal sampling with the IOM foam sampler provided an important benefit in the power plant, where the concentration ratio of personal to stationary samples was much higher for bacteria than for inhalable or respirable dust.

Urinary NAG and GAG as biomarkers of renal effects in exposure to 2-alkoxyalcohols and their acetates.

Many sensitive biomarkers are available for the surveillance of the early health effects of chemicals on humans. This study was conducted to evaluate the usefulness of glycosaminoglycans (GAG) as biomarkers of early kidney effects in exposure to 2-alkoxyethanols and their acetates. GAG were compared with effects on the urinary beta-N-acetylglycosaminidase activity (NAG). According to the results of the present study, the excretion rate of GAG was higher among women than men. On the other hand, the excretion rate of GAG was lower among exposed subjects than among the controls, and the level was decreased at the tested levels of exposure. The NAG activity was higher in most of the exposed groups than in the controls. The data indicated that an appropriate urinary limit value for ethoxyacetic acid was 30 mmol/mol creatinine in postshift samples and that this value corresponded to an 8-hour exposure level of 2 cm3/m3 2-ethoxyethylacetate. Urinary butoxyacetic acid excretion of 60 mmol/mol creatinine corresponded to the inhalation exposure level of 5 cm3/m3 2-butoxyethanol and its acetate in postshift samples.

Urinary biochemistry in occupational exposure to glycol ethers

Glycol ethers and glycol ether acetates are dehydrogenated to alkoxyacetic acid congeners which may serve as biological indicators of exposure. The ethereal bond may also be cut in an oxidation reaction catalyzed by the mixed function oxidase. In case of ethylene glycol, the eventual endproduct is oxalic acid. Urinary oxalic acid and alkoxyacetic acid excretion together was found to relate to the decrease of the succinate dehydrogenase activity (SDH) as an indicator of renal mitochondrial effects. The excretion of ammonia by exposed workers was doubled as compared to controls. The excretion of chloride was found to be smaller in the exposed than in controls. The excretion of calcium and glycosaminoglycans (GAG) among exposed workers were similar compared to controls.

Rat model for renal effects of 2-alkoxyalcohols and their acetates

Abstract Male Wistar rats were given ethanediol (9.4 g/l), 2-ethoxyethylacetate (5.4 g/l), 2-butoxyethylacetate (2.9 g/l) and 1,2-propanediol (40 g/l) respectively in their drinking water for 2 weeks. Urine was collected during the last 24 h of the exposure. There was a marked increase in the oxalic acid excretion by the rats given ethanediol while rats given the alkoxyacetates excreted large amounts of ethoxyacetic and butoxyacetic acid, respectively. While not increased compared with controls, the excretion of oxalic acid by the latter group of rats was correlated to the excretion of the respective alkoxyacetic acids. The ammonia and glycosaminoglycan excretion was also smaller than that of controls. The urinary activity of succinate dehydrogenase was decreased in rats given the alkoxyacetates but not in animals exposed to ethanediol or propanediol. The data show that oxalic acid is actually a minor metabolite of the alkoxyacetates while the biochemical effects in kidney are associated more with the alkoxyacetic acid load. Alkoxyacetic acids seem to be inhibitors of renal succinate dehydrogenase, which may account for the decreased ammonia and glycosaminoglycan excretion.