The microenvironment of polycarbonate cages housing rats with and without various types of bedding was compared with that of cages that utilized wire floor inserts with different bedding types. Parameters monitored were temperature, humidity, ammonia concentrations and particulates. No differences were noted in the various caging types in relation to temperature and humidity measurements. Significant differences in ammonia concentrations existed in some of the cages when bedding material was used. The use of raised floorwalk inserts also demonstrated significant differences in particulate counts to cages without inserts. The data obtained demonstrated that contact bedding was useful in controlling ammonia generation and that a raised floorwalk insert reduced significantly the aerosolization of bedding particles that could be ingested or inhaled by the rats.

A commercially available water purification system was evaluated for its ability to minimize chemical and microbial contaminants. The reduction or removal of these impurities from the drinking water of experimental animals would reduce experimental variability. 3 strains of bacteria were collected from the processed water. An increase in the total number of bacteria was observed the longer the filters remained in use. Determinations of heavy metals in water samples before and after processing were made for lead, zinc, copper, nickel, manganese, iron, arsenic and mercury. Calcium and magnesium levels were also determined. The concentrations of these inorganic chemicals were reduced by the purification process except at 2 time points in which desorption of the chemical could have occurred. Bacterial colonization and desorption of these chemicals were controlled by installing new filter cartridges. Volatile halocarbon concentrations were determined for water samples before and after purification. All volatile halocarbons analyzed were less than 10 ppb before and after purification at all time points. Other organic chemicals were greatly reduced by the purification process. In a study of contaminants associated with installation of the unit, it was found that flushing the unit for 8 days reduced lead and methyl ethyl ketone concentrations to insignificant levels. The purification system was found to be effective in providing high quality drinking water as verified by a microbial and chemical testing program.

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