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Health hazard evaluation report: HETA-80-101-1157, Cincinnati Zoo, Cincinnati, Ohio.
Johnson P; Singal M
Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, HETA 80-101-1157, 1982 Aug; :1-15
In response to a request from the Health Department of Cincinnati, an evaluation was made of exposures to silica (7631869) dust and bird droppings at the Cincinnati Zoo (SIC-8421), Cincinnati, Ohio, occurring among workers involved in cleaning the bird cages. There were six workers assigned to the aviary area. Sand covered floors of the cages were swept with brooms to remove bird droppings and other debris. The materials from the sweepings were then scooped into a screened bottom shaker box and shaken to separate sand and debris. Treated or cleaned sand was returned to the cages while the waste was dumped into a waste container for removal. Positive tuberculin skin tests had occurred among some workers, causing concern. Air samples were taken and the respirable dust concentrations were found to range from 1.7 to 2.1 milligrams per cubic meter (mg/m3) and free silica concentrations from 0.32 to resulting 8 hour time weighted average free silica concentrations ranged from nondetectable to 0.1mg/m3 with three of four samples exceeding NIOSH recommended levels. However, these exposures were for periods of 45 minutes to an hour, once or twice a month, and for not more than a few years. No excess occurrence of respiratory disease was found at the zoo, but the rate of tuberculin reactivity was higher than expected. Two former employees with active tuberculosis acquired outside the zoo may have been a source for transmission. The authors conclude that it is unlikely that the silica exposures constitute a hazard. The authors recommend that the substitution of other materials for the sand might lower the exposure to crystalline silica. A ventilation system should be established in the individual bird cages, not only for dust control but also for temperature control. Testing for tuberculosis should be expanded to include all the employees.
NIOSH-Author; NIOSH-Health-Hazard-Evaluation; NIOSH-Technical-Assistance-Report; HETA-80-101-1157; Region-5; Hazard-Unconfirmed; Silica-dusts; Airborne-dusts; Ventilation-systems; Epidemiology; Infectious-diseases; Author Keywords: Arboreta, Botanical, and Zoological Gardens; Crystalline Silica; Tuberculosis; TB Skin Test
Field Studies; Hazard Evaluation and Technical Assistance
NTIS Accession No.
National Institute for Occupational Safety and Health
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division