Author(s): TERESA A SEITZ, SCOTT DEITCHMAN
A health hazard evaluation (HHE) was conducted in the AIDS Clinical Trial Unit at the George Washington University (GWU) Medical Center to evaluate exposures to pentamidine isethionate. This work was performed in response to a request submitted by a management representative at the facility. Aerosolized pentamidine (AP) had been administered to AIDS patients for prophylaxis against Pneumocystis carinii pneumonia (PCP) since January 1989. A case of interstitial fibrosis had been diagnosed in one of the health care workers (HCWs) responsible for administering the drug. A few other HCWs working in the area of administration were reported to have abnormal pulmonary function tests (PFTs), but baseline PFTs were not available for these workers. Prior to the NIOSH evaluation, changes in the pentamidine administration procedure had been made. These changes included the administration of pentamidine in a small room (rather than in an open area within the clinic), an increase in the number of room air changes per hour, the establishment of negative air pressure with respect to surrounding areas, and the provision of a glass panel on the door through which observations of the patients could be made while the health care worker remained outside. Environmental measurements made in May 1991 revealed a concentration of 0.04 microgram per cubic meter (µg/m3 ) pentamidine isethionate in a personal breathing zone air sample obtained on the nurse involved in AP administration, and 0.09 and 0.13 µg/m3 in area air samples obtained outside the treatment room. These air concentrations are more than 100-fold lower than those measured in the AP treatment room during six AP treatments given over the course of approximately three hours. There are presently no occupational exposure criteria for pentamidine isethionate. The medical evaluation consisted of employee interviews and a review of available medical records including pulmonary function test results for 11 employees. Of 4 employees interviewed, two reported occasional symptoms of mild chest tightness associated with exposure to AP; one reported experiencing these symptoms occasionally, while the other reported only a single episode. This may reflect mild, reversible bronchospasm, which has been reported in both patients and workers exposed to pentamidine. There were also reports of mucosal irritation; however, both the irritative symptoms and chest tightness resolved or decreased after the changes (noted above) in work practices and ventilation were instituted. Eight employees were reported to have abnormally low pulmonary diffusing capacity. Only one employee reported symptoms of dyspnea. Retesting of four employees at another site indicated that their pulmonary diffusing capacities (DLCO) were within limits of normal, using different comparison populations. A test of pentamidine-induced lymphocyte stimulation was performed using blood from 8 of the 11 employees; although all 8 employees showed some degree of lymphocyte stimulation to pentamidine, no association was found between the degree of stimulation and the DLCO values.