Aspergillus and other human respiratory disease agents in turkey confinement houses.

The atmosphere of a turkey confinement house on a large Minnesota farm was examined over the course of a year in order to determine levels of airborne contaminants and to evaluate the hazard potential posed by the contaminants to farm workers. Air concentrations of total and respirable dust, ammonia, carbon monoxide, hydrogen sulfide, nitrogen dioxide, methane, and Aspergillus (a fungal respiratory disease agent) were evaluated. Inter- and intra-seasonal variations in confinement house contaminant concentrations were observed. The highest concentrations of dust, ammonia and Aspergillus occurred during the winter months when dust levels averaged 9.3 mg/m3 and ammonia levels averaged 35 parts per million (ppm). Aspergillus levels were lower than expected, never exceeding 73 colony forming units per cubic meter (cfu/m3). Ammonia levels were found to be particularly high during tilling of the confinement house when concentrations greater than 100 ppm were reached. Concentrations of carbon monoxide, hydrogen sulfide, nitrogen dioxide and methane were below detectable levels.

Development of a model to aid in reconstruction of historical silica dust exposures in the taconite industry.

The ability to reconstruct employee exposure histories would be a valuable research tool for the evaluation of occupation as a factor in disease. In many cases, however, historical environmental data are available but have not been used to compute past exposures because of differences in sampling methods. This paper describes a quantitative model to convert historical environmental data (from taconite mine and mill operations) into a form consistent with current sampling methods and results and, therefore, will enable past exposure histories to be used. (Past exposure histories are to be determined in an epidemiological study.) In this study, parallel sampling results from the environmental data base were used to obtain a coefficient for the conversion of impinger-particle counts (old sampling method) to filter-respirable mass sampling results (new sampling method). Parameters in the model were estimated using multiple regression techniques. Results show that a consistent ratio exists between impinger-particle counts and filter-respirable mass concentrations for samples collected at the same locations.

Respiratory exposure of grain inspection workers to carbon tetrachloride fumigant.

Carbon tetrachloride (often mixed with carbon disulfide or ethylene dichloride) is a common constituent of liquid grain fumigants. Applied as liquids, these mixtures volatilize and achieve vapor concentrations sufficient to control insect infestations in stored grains. Absorbed grain desorbs fumigant components after the fumigation period, and it then becomes a source of exposure to workers who handle fumigated grain. Carbon tetrachloride meets the EPA's risk criteria for hepatotoxicity, nephrotoxicity and oncogenicity, and it has been under regulatory review since 15 October 1980. Present OSHA standards for CCl4 are a time-weighted average (TWA) of 10 ppm and an acceptable ceiling of 25 ppm. ACGIH and NIOSH have recommended lowering the OSHA standard. The point at which peak exposure occurs during the grain inspection process has been identified as the off odor test in which the inspector smells the grain sample for rancidity, sourness, etc. Ambient concentrations of CCl4 in 7750 grain samples submitted for inspection were determined by colorimetric tube, and these concentrations were an estimate of peak grain inspector exposure to CCl4. The average ambient concentration of CCl4 per grain sample was 1.69 ppm +/- 8.35. Approximately 380 TWA CCl4 exposures for grain inspection workers were determined by using passive dosimeters. All TWA exposures were less than 2 ppm. Variables are examined, such as location of work, grain type, time of year and grain transportation vehicle--all of which are known to the sampler or inspector before performing their job functions and which affect potential exposure.

Validation of a colorimetric method for determination of atmospheric formaldehyde.

Aqueous formaldehyde was stabilized in pH 7 phosphate buffer with excess sodium bisulfite of fixed and known concentration. The 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) procedure described previously was used to determine excess bisulfite colorimetrically. The slope of the calibration line (absorbance at 412 nm vs. formaldehyde concentration) is -0.350 A.U./ug CH2O/mL (correlation coefficient: 0.9995). The precision of the method at the 95% confidence level is indicated by the mean percentage relative error (1.81 +/- 1.67) and mean percentage standard error (0.42 +/- 0.39). Gaseous formaldehyde of known concentrations (ppm) in air was absorbed from air samples in pH 7 buffer and determined by the DTNB method. For the determination of formaldehyde in air, the precision and accuracy were demonstrated at the 95% confidence level by the mean percentage relative error (5.04 +/- 3.2), the mean percentage standard error (1.72 +/- 1.0), the mean percentage recovery (99.9 +/- 2.7), and the mean percentage absolute error (1.86 +/- 1.6). The graphic comparison of air concentration found vs. air concentration calculated shows a slope of 0.993 ppmfound/ppmcalcd (correlation coefficient: 0.9993).

Validation of a simpler method for determination of atmospheric sulfur dioxide.

The determination of atmospheric sulfur dioxide as aqueous bisulfite using 5,5'-dithiobis (2-nitrobenzoic acid) (DTNB) was validated as a simple, rapid and reliable procedure. Standard sulfur dioxide concentrations in air (0-2.6 ppm) were generated by means of a permeation device. Sulfur dioxide from air samples was absorbed in pH 7 phosphate buffer and determined as bisulfite. The mean percentage recovery of sulfur dioxide is 101.4; the slope of the validation line determined by linear regression analysis (calculated vs. found) is 1.014 ppm found/calculated (1.4% absolute error; 0.9976 correlation coefficient).

Ethylene oxide dispersion from gas sterilizers.

Ethylene oxide (EtO) is widely used by the health industry for sterilizing heat-sensitive devices. About 100 000 workers are regularly exposed to this chemical, used in an estimated 10 000 sterilizing units in U.S. health care facilities. Based on recent findings. NIOSh has recommended that EtO be regarded as a potential carcinogen and has urged OSHA to reexamine its present standard of 50 ppm. The ACGIH Notice of Intended Changes for 1982 has proposed reducing the recommended limit from 10 ppm TWA to 1 ppm and considers EtO a suspect carcinogen for man. Because of this increasing concern for its toxicity, it is imperative that the exposures to EtO be assessed, and that all reasonable steps to reduce these exposures be taken. This study demonstrates the effects of local exhaust ventilation, sterilizer chamber temperature, and sterilizer relative humidity in relation to their influence on EtO plume directionality, concentration and duration. Using two Foxboro/Wilks Miran 1A General Purpose Gas Analyzers, EtO concentrations were simultaneously monitored both immediately above and below the sterilizer door during various process runs, at three different types of sterilizers. Sterilizer operating conditions were representative of temperatures (38-54 degrees C (100-130 degrees F)), and relative humidities (30-50%) commonly employed in the sterilization process. The effects of varying local exhaust parameters were observed. Results clearly demonstrated that EtO tends to flow upward when the sterilizer door is opened. In all cases, the highest concentrations were observed at the upper location. Local exhaust ventilation significantly reduced the concentration of EtO observed and lessened the duration for which these levels persisted. Changes in temperature and relative humidity, within the range cited, have not shown any significant differences in EtO evolution patterns, concentrations or duration.

Getting the message to the farmer.

The farm worker has been a difficult person to reach with information on the health hazards present in his/her work environment, even though the typical farm is a potentially dangerous place to work. The University of Minnesota Agricultural Extension Service has used OSHA 'New Directions' funding to develop a program specifically designed to increase the farmers' awareness of occupational health and safety hazards. The information has been packaged in units which can be used effectively by those people such as county agents, Vo-Ag teachers, and chemical dealers who have regular contact with the farmer. Each unit focuses on a single hazard such as noise, airborne substances and farm machinery repair. Slides and an audio cassette are provided along with background information for the instructor, a "pre" and "post" test, and discussion questions. Workshops providing instruction on the use of the materials are held through out the state at regular intervals.

Can an erc consortium work?

The Midwest Occupational Safety and Health Center is one of twelve regional NIOSH funded Educational Resource Centers. This Center is unique, however, in that it was formed as a consortium between five geographically distinct institutions -- The University of Minnesota, Twin Cities Campus, The University of Minnesota, Duluth Campus, Mayo Clinic, St. Paul-Ramsey Medical Center and The University of Iowa, Oakdale Campus. The advantages and disadvantages of such a consortium are discussed with respect to the five functional roles of an ERC: program, faculty, research, continuing education and outreach. The author views this consortium as a success, particularly with respect to the latter two functional roles.

Decreased T cell function in mice exposed to chronic, low levels of lead.

The immune responsiveness of mice given low levels of lead acetate (1300 p.p.m.) in their drinking water for 8 weeks was determined. Mean percentages of splenic T and B lymphocytes in lead-exposed mice were slightly lower than in controls. Mean mitogen response to phytohaemmaglutinin and concanavalin A in mice exposed to lead was significantly decreased compared to controls. The response to lipopolysaccharide on the other hand was not significantly mitogenic response to phytohaemagglutinin and concanavalin A is impaired in mice exposed chronically to low concentrations of lead.

Influence of relative humidity on functional effects of an inhaled SO2-aerosol mixture.

Lightly anesthetized guinea pigs were exposed to 1 ppm of sulfur dioxide (SO2) and 1 mg per m3 of sodium chloride aerosol, individually and in combination, at low and high relative humidities. At low relative humidity (less than 40 per cent) the aerosol was a crystal, at high relative humidity (greater than 80 per cent) a droplet. Exposures lasted one hour. Changes in pulmonary mechanical function characterized by an increase in flow resistance and decrease in compliance were seen only when the mixture was administered at high relative humidity. The effect is ascribed to absorption of the highly soluble SO2 into the droplet before inhalation.