The measurement of urinary cobalt as an estimator of exposure to airborne cobalt was evaluated during the wet sharpening of hard metal and stellite blades. The following possible confounding factors were also studied: smoking habits, personal hygiene, cobalt absorption through the skin, beer drinking, and vitamin B12 consumption. The study was conducted in 16 different workplaces manufacturing or maintaining blades and in laboratory experiments. Cobalt contamination and its removal from workers' hands were studied with different hand-washing methods, and cobalt from used gloves was also analyzed. The Finnish biomonitoring action level of 600 nmol/l (35.4 micrograms/l) was exceeded in 4 of the 16 workplaces, and the mean concentration of urinary cobalt was 241 (8-2705) nmol/l [14.2 (0.5-160) micrograms/l]. The coefficient of correlation between the cobalt concentrations in the air and in the workers' urine was 0.753. The urinary cobalt concentration corresponding to the Finnish occupational exposure limit for airborne cobalt (0.05 mg/m3) was 686 nmol/l (40.5 micrograms/l). The level of personal hygiene affected the urinary cobalt concentrations, and cobalt was absorbed through the skin. Beer and vitamin B12 consumption did not have any effect on the urinary levels of cobalt. The workers who smoked had higher urinary concentrations of cobalt than the nonsmoking workers. High concentrations of cobalt in coolants contaminated the workers' skin, and hand-washing did not remove cobalt very effectively. The results indicate that urinary cobalt can be used reliably to assess workers' exposure to airborne cobalt when wet-tip grinding processes are used. The results also show that workers' exposure to cobalt can be reduced by improving skin protection and personal hygiene in workplaces.
SummaryIn work environments with laboratory animals, the bedding of animals binds the excreta as well as other compounds originating from the animals and their environment. These may be generated into the ambient air when the personnel handle bedding in different procedures. This study compares the dustiness of different types of six clean and four soiled beddings from rat or mouse cages. The dust generation of clean bedding varied from <1 to 25 mg=m 3 . When used in the cages of rats or mice for 4 days, the dust concentration of the beddings decreased, increased or stayed the same, depending on the type of bedding and animal species. A decrease in dustiness was, however, more common. The levels in the soiled beddings varied from <1 to 8.6 mg=m 3 . In the case of the aspen chip bedding, the contents of bedding used in mouse, rat or rabbit cages were analysed for mesophilic bacteria and fungi, mycobacteria and endotoxins. All of these contaminants were variably found in the bedding samples, the maximal concentrations for bacteria were >6 500 000 colony-forming units (cfu)=g, for fungi 212 000 cfu=g, and for endotoxins 6500 ng=g (81 000 EU=g). The results showed that the bedding of laboratory animals may contain biologically effective compounds, and that these may be distributed into the ambient air depending on the characteristics of the bedding material. The dustiness of different bedding types is an important factor affecting the amount and quality of the occupational exposure of the personnel to airborne contaminants.
The results clearly proved that in occupational hygiene measurements, endotoxins serve as excellent indicators of exposure to the microbial contaminants of MWF. IgG antibodies against antigens identified from workplace samples could be a practical tool for occupational health physicians.
Particulate matter (PM) from mining operations, engines, and ore processing may have adverse effects on health and well-being of workers and population living nearby. In this study, the characteristics of PM in an underground chrome mine were investigated in Kemi, Northern Finland. The concentrations and chemical composition of PM in size ranges from 2.5 nm to 10 mm were explored in order to identify sources, formation mechanisms, and post-emission processes of particles in the mine air. This was done by using several online instruments with high timeresolution and offline particulate sampling followed by elemental and ionic analyses. A majority of sub-micrometer particles (<1 mm in diameter, PM 1 ) originated from diesel engine emissions that were responsible for a rather stable composition of PM 1 in the mine air. Another sub-micrometer particle type originated from the combustion products of explosives (e.g., nitrate and ammonium). On average, PM 1 in the mine was composed of 62%, 30%, and 8% of organic matter, black carbon, and major inorganic species, respectively. Regarding the analyzed elements (e.g., Al, Si, Fe, Ca), many of them peaked at >1 mm indicating mineral dust origin. The average particle number concentration in the mine was (2.3 § 1.4) Ã 10 4 #/cm 3 . The maximum of particle number size distribution was between 30 and 200 nm for most of the time but there was frequently a distinct mode <30 nm. The potential origin of nano-size particles remained as challenge for future studies.
SummaryBesides the well known allergens, several other risk factors may exist for health in a laboratory anim al unit. T he exposure to these factors may be signi®cant in animal units with poor general or local ventilation systems. Moreover, means to prevent the distribution of airborne contaminants may be limited in animal units housing rabbit s or other bigger laboratory animals. Airborne contaminants in conventional laboratory rabbi t rooms were sought to evaluate the occupational exposure of animal care personnel. Concentrations of airborne dust, bac teria, fungi, ammonia and endotoxins were measured during 2 days in three phases: before working acti vities began, during them and aft erwards. Both stati onary and some personal samples were taken. All of the contam inants sought were found in the rabbi t room air. When compared to reported levels in farm animal production areas, the concentrations measured were generally low. However, moderate or high levels of airborne bac teria and fungi were found occasionally during work routines. Airborne contaminants should be considered as a potential occupational health risk for persons working with laboratory animals.
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