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Biomedical subjects

B V Mokler

Publications and source records attributed to B V Mokler.

12 recordsLinked to original sources
PubMed1987

Hospitals and the hazard communication standard.

The previous three articles in this four-part series introduced the need for hazardous waste management in hospitals, the regulatory background, insights for determining which hospital waste streams are hazardous or infectious, and practical aspects of hazardous waste management for hospitals. In this final article in the series, the author focuses on the requirements of the federal Hazard Communication Standard, its relationship with state and local "right to know" laws, and actions a hospital should take to institute a hazard communication program.

Accident Prevention↗
PubMed1984

Diesel exhaust exposure system for animal studies.

Planned exposures of rodents to diesel exhaust required development of an exhaust generation and delivery system flexible enough to accommodate varied experimental designs. The features of the exposure system built to meet these needs are summarized. Essential aspects including both the exhaust dilution and delivery system and the computer monitoring and control functions are described. During the first 29 weeks of a study with target particle concentrations of 350, 3500, and 7000 micrograms/m3, the achieved values were 310, 3360, and 6830 micrograms/m3 with coefficients of variation of 23, 10, and 9%, respectively. The system has now operated reliably for more than 24 months.

Animals↗
PubMed1984

Chemical and biological properties of diesel exhaust particles collected during selected segments of a simulated driving cycle.

Particle emissions, percentage of organic extractable materials, and mutagenicities of extracts from a diesel engine operating on a test stand have been determined for the full Federal Test Procedure driving cycle and several individual segments thereof. Particle samples were collected using a computer controlled high volume sampler. Extracts of the exhaust particles were screened for the potent mutagens nitropyrene/nitrofluoranthenes by mass spectrometry/mass spectrometry (MS/MS). Results indicate that a long acceleration from 0-55 mph produced approximately seven times more particles per second than the full cycle. Also, the 0- to 55-mph acceleration and a subsequent 55-mph cruise produced significantly higher amounts of mutagens than other segments or the full FTP cycle. A direct correlation of both NOx levels and temperature with mutagenicity was noted (r = 0.89 and r = 0.89). The specific activities of the extracts showed decreases or remained unchanged when assayed in TA-98 NR or TA-98 1,8 DNP6, nitroreductase deficient strains of TA-98. Three extracts were found to have high levels of nitropyrenes/nitrofluoranthenes, and two of the three had high specific activities in TA-98.

Mutagenicity Tests↗
PubMed1984

Characterization of diesel exhaust in a chronic inhalation study.

We describe characterization of the exposure atmosphere in a life-span study of rats and mice exposed to chronic inhalation of diluted diesel exhaust. Diesel exhaust was generated by one of two General Motors 1980 Model, 5.7-liter V8 diesel engines connected to an eddy current dynamometer/flywheel system and operated on the Federal Test Procedure urban driving cycle. Animals were exposed 7 hours/day, 5 days/week to exhaust at particle concentrations of approximately 7000, 3500, and 350 micrograms/m3 or to clean air. Throughout the 24-month study, the mean particle mass concentration remained within 5% of the target values. Measured gas concentrations of CO, CO2, NO, NO2, and hydrocarbons were roughly proportional to the dilution ratio. A combination of a Lovelace Multijet cascade impactor followed by a parallel flow diffusion battery gave mass median diameters of 0.23 to 0.26 microns averaged over complete cycles and geometric standard deviations larger than 4. The aerosol concentration profile was associated with the operating cycle. The measured diesel particle size was similar to previously reported values of particles released to the atmosphere from the same model engine.

Animals↗
PubMed1983

Influence of elastase-induced emphysema and the inhalation of an irritant aerosol on deposition and retention of an inhaled insoluble aerosol in Fischer-344 rats.

The purpose of this study was to assess the effects of elastase-induced pulmonary emphysema and the inhalation of an irritant aerosol (Triton X-100, a nonionic surfactant similar to those used in a number of pressurized consumer products) on pulmonary deposition and retention of an insoluble test aerosol, 59Fe-labeled Fe2O3. Untreated rats or rats pretreated by intratracheal instillation with elastase were exposed to an aerosol of 59Fe-labeled Fe2O3 either 18 hr or 7 days after exposure to aerosolized Triton X-100 which was administered in doses of 20, 100, or 200 micrograms/g of lung. Rats pretreated with elastase had significantly lower pulmonary deposition of 59Fe than the untreated controls (p less than 0.005). Pulmonary deposition of Fe2O3 was unaffected by pretreatment with Triton X-100. Elastase treatment alone had no effect on retention of Fe2O3. Triton X-100 administered 18 hr prior to exposure of rats to Fe2O3 aerosol resulted in dose-related increases in whole-body retention of 59Fe. When rats were exposed to Triton X-100 7 days before exposure to Fe2O3, increased retention of 59Fe was noted only in those treated at the highest Triton X-100 dose level (200 micrograms/g).

Aerosols↗
PubMed1983

Cytotoxicity and mutagenicity of vapor-phase pollutants in rat lung epithelial cells and Chinese hamster ovary cells grown on collagen gels.

Lung epithelial cell (cell line designated LEC) and Chinese hamster ovary (CHO) cells were grown on hydrated collagen gels and exposed directly to toxic vapor-phase pollutants. The cells were exposed to graded concentrations of phenol, formaldehyde, a volatile fraction of process stream material from an experimental coal gasifier and the nonparticulate, vapor phase of diesel engine exhaust. During exposures, the cells were maintained at an air/collagen interface by removing the medium overlying the hydrated collagen gel. Morphological changes indicative of cell retraction were found in LEC cell cultures exposed to phenol, formaldehyde, or diesel exhaust. Damage following exposure to the toxicants was quantitated in LEC and CHO cells by Trypan blue dye exclusion, a measure of plasma membrane integrity. Clone-forming ability was also used to measure cell survival in CHO cells. When measured by Trypan blue dye exclusion, phenol (EC50 = 2.1 mg/l) caused membrane damage to LEC cells but not CHO cells, while formaldehyde (EC50 = 31 and 42 micrograms/l for LEC and CHO, respectively) and diesel exhaust (EC50 = 11 and 29% of tailpipe exhaust in LEC and CHO cells, respectively) caused damage to both cell types. No cytotoxicity was observed in LEC or CHO cells exposed to the fraction from the coal gasifier. Essentially no mutagenic activity was associated with the exposure of CHO cells to formaldehyde or the vapor phase of diesel exhaust. Mutagenic activity was found in CHO cells exposed to ethylene oxide, the positive control. The results of this study indicate that mammalian cells grown on collagen gels can readily be exposed to vapors of chemicals and chemical mixtures. The cell exposure system may be generally useful in the analysis of toxic damage to mammalian cells resulting from gaseous or vapor-phase pollutants.

Air Pollutants↗
PubMed1979

Respirable particulates generated by pressurized consumer products. I. Experimental method and general characteristics.

Many products and materials are available in the widely used pressurized package or "aerosol" form. A simulated breathing zone model approach has been developed and used to characterize the particles to which a user may be exposed. Some products characterized under simulated "worst reasonable" conditions produced concentrations of particulates smaller than 6 micrometer aerodynamic diameter exceeding 50 mg/m3.

Aerosols↗
PubMed1979

Respirable particulates generated by pressurized consumer products. II. Influence of experimental conditions.

The many products available in pressurized packages produce appreciable concentrations of particulates that may be deposited in the deep lung of human users. We have reported the size and concentration characteristics of these aerosols under carefully standardized conditions in a previous paper. These standard conditions have been varied to determine the influence of product discharge conditions on observed aerosol characteristics. The size characteristics are relatively insensitive to a wide range of changes in the discharge conditions; the only significant effect observed followed changing the target of the spray from a steel plate to a wig. The aerosol concentrations were changed by several experimental factors, but the relative changes were less than the estimated relative range of human exposure.

Aerosols↗
PubMedDate not supplied

Clearance of diesel soot particles from rat lung after a subchronic diesel exhaust exposure.

The particulate exhaust of diesel engines consists of 0.1--0.2 micrometers mass median diameter particles composed of a carbonaceous core and adsorbed organic compounds. A technique was needed to determine accumulated lung burdens of particles in animals exposed to diesel exhaust as a determinant of dose. A method was developed for determining lung burdens of diesel soot particles in rats at 1 day, and at 1, 5, 15, 33 and 52 weeks after cessation of a subchronic exposure to diluted diesel exhaust. Lung tissue was dissolved in tetramethylammonium hydroxide and the diesel soot separated by centrifugation. The soot was suspended in water by sonication and the light absorption of samples was compared to standard suspensions of diesel soot. Recovery from lungs spiked with 50-1000 micrograms of soot was 89 +/- 5%. Rats exposed over a period of 18 weeks to diluted diesel exhaust at average net diesel particles concentrations of 150, 940 and 4100 micrograms/m3 had lung burdens of 35, 220 and 1890 micrograms/g lung, respectively, one day after the last exposure. The long-term clearance rates of soot had estimated half-times of 87 +/- 28, 99 +/- 4 days, for the low and medium exposure groups, respectively. The clearance half-time for the high level exposure group of 165 +/- 8 days was significantly longer (P less than 0.0001) than those of the other two groups.

Animals↗