Eugene C. Cole

Stability and bactericidal activity of chlorine solutions

OBJECTIVES To determine the stability of sodium hypochlorite (diluted household bleach) when stored for 30 days in various types of containers and to determine the efficacy of low concentrations of free available chlorine to inactivate test bacteria. DESIGN Laboratory-based study. Solutions of standard household bleach were prepared using tap water or sterile distilled water at dilutions of 1:100, 1:50, and 1:5. Chlorine concentrations were measured, and then the solutions were placed into five polyethylene containers and left at room temperature (20 degrees C) under various conditions (translucent containers with light exposure and with or without air; brown opaque container without light or air exposure). Samples for chlorine and pH determinations were taken at time 0 and on days 7, 14, 21, 30, and 40. Bactericidal activity of chlorine solutions was assessed using the Association of Official Analytical Chemists Use-Dilution Method. Test bacteria included Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella choleraesuis. RESULTS Chlorine concentrations at 30 days varied from the 40% to 50% range for 1:50 or 1:100 dilutions stored in containers other than closed brown containers to 83% to 85% for the 1:5 dilution stored in closed but non-opaque containers to 97% to 100% for 1:50 or 1:5 solutions stored in closed brown containers. The lowest concentration of sodium hypochlorite solution that reliably inactivated all the test organisms was 100 ppm. CONCLUSIONS These data suggest that chlorine solutions do not need to be prepared fresh daily, as is recommended currently, and the lowest concentration of chlorine that reliably inactivates S aureus, S choleraesuis, and P aeruginosa is 100 ppm.

Viable sampling for airborne bacteria in a poultry processing plant

Air was sampled for viable bacteria in the shackling room of a poultry processing plant. Large numbers of bacteria were isolated from the workers’ breathing zone, and gram‐negative organisms were characterized. The probable source of airborne gram‐negative bacteria and their endotoxins was identified as the birds’ feces. These data suggest a potential health risk for workers due to inhalation of viable bacteria.

Respiratory Illness in Workers of an Indoor Shiitake Mushroom Farm

Abstract Shiitake mushrooms (Lentinus edodes), the second most important mushroom in world commerce, are usually grown on logs outdoors. Because of the relatively short harvesting period and weather dependency of shiitake strains that are cultivated outdoors, there is a trend toward indoor cultivation of strains that can permit year-round production. An evaluation of an indoor shiitake farm was conducted following reports that workers of the facility were experiencing symptoms of respiratory illness. During private interviews that included the administration of a questionnaire, 11 workers reported seven or more symptoms which they had experienced either during work or shortly after leaving work; six of these workers reported 15 or more symptoms. Predominant symptoms were dry cough, nasal discharge, sneezing, chest tightness, productive cough, and dyspnea. Based upon the results of the acute symptoms questionnaire and preliminary bioaerosol sampling, the management of the shiitake farm discontinued operati...