Evaluation of the ceiling levels of ortho-phthalaldehyde exposure among health care workers engaged in endoscope disinfection: A new methodology using video-exposure monitoring.

OBJECTIVES: The present study aimed to develop a method for measuring the ceiling level of ortho-phthalaldehyde (OPA) exposure and evaluate the ceiling levels of OPA exposure among health care workers who handle disinfectant solutions containing OPA for the disinfection of endoscopes. METHODS: The study consisted of a preliminary survey and main survey. In the preliminary survey, processes involving high-concentration exposure to OPA were identified by video-exposure monitoring (VEM). In the main survey, the ceiling levels of OPA exposure for high-concentration exposure processes identified from the results of the preliminary survey were determined using a measuring method combining sampling using a 2,4-dinitrophenylhydrazine-silica cartridge and analysis by high-performance liquid chromatography tandem mass spectrometry. RESULTS: In the preliminary survey, seven processes involving high-concentration exposure to OPA were identified by VEM. The duration of each process was short, lasting from 20 seconds to a few minutes. In the main survey, the OPA concentrations for the identified high-concentration exposure processes ranged from 1.18 to 4.49 ppb, which markedly exceeded the threshold limit value ceiling (TLV-C) of 0.1 ppb recommended by the American Conference of Governmental Industrial Hygienists. CONCLUSIONS: The method for measuring the ceiling level of OPA exposure was established using VEM and the highly sensitive method of chemical analysis; and we successfully evaluated the ceiling levels of OPA exposure among health care workers engaged in endoscope disinfection. This approach can also be applied to other chemical substances with recommended TLV-Cs, and important information for reducing exposure can thus be obtained.

A strategy for the reduction of formaldehyde concentration in a hospital pathology laboratory.

OBJECTIVES: Formaldehyde is routinely used in pathology laboratories. The threshold limit value of formaldehyde determined by American and Japanese organizations is 0.1 ppm, which is similar to the indoor air quality guideline value (0.08 ppm). Therefore, maintaining low formaldehyde concentrations in the workplace is imperative. The purpose of this study was to reduce the concentration of formaldehyde in a hospital pathology laboratory, in which approximately 15 000 pathological diagnoses are conducted yearly, using hardware and software interventions. METHODS: Although this laboratory had various ventilation systems, the formaldehyde concentration was high. Based on the Japanese work environment measurement system, the workplace was categorized as control class III, suggesting that improvements to workplace conditions were required. First, engineering controls were implemented and workers were asked not to block the ventilation system and not to keep waste fluid tanks open. However, the workplace required further improvement. Next, using a video camera and a formaldehyde detector, we attempted to visually educate workers about how much formaldehyde is emitted from the sample container based on the type of action undertaken. RESULTS: After the first intervention, the workplace improved to control class II. Control class II indicates that the workplace condition is between classes I and III; a good workplace condition is classified as class I. Although the work environment was still categorized as control class II after the second intervention, this intervention led to the further improvements. CONCLUSIONS: The hardware and software interventions and safe working habits were effective in improving the work environment.