EXPOSURE OF ONCOLOGIC NURSES TO METHOTREXATE IN THE TREATMENT OF OSTEOSARCOMA

Methotrexate is a therapeutic agent used widely for osteosarcoma. We u sed an extremely sensitive high-performance liquid-chromatography assa y to evaluate 112 urine samples obtained from 28 hospital employees du ring high-dose therapy with methotrexate and during routine care of pa tients. The highest cumulative urinary excretion was observed when met hotrexate infusions were handled in a workbench from which a portion o f filtered air was emitted into the room. Remarkable urine contaminati ons were identified for personnel, including 1 administrative employee who had ''stood by'' for 2 h in the room where infusions were prepare d. Lower methotrexate concentrations were detected in the urine of nur ses whose exclusive function was to care for patients. The urine burde n in oncologic nurses decreased after a central pharmacy unit was inst alled. Methotrexate was excreted in the sweat of patients who were und er high-dose therapy, and its elimination half-life was 11.1 h (mean m aximal concentration = 1.7 mu g/ml [n = 5]). The maximal burden in spo ntaneous vomit from these patients was 441.5 mu g/ml, and it declined to 0.24 mu g/ml 19.5 h after infusion was completed. No methotrexate w as detected in personnel who prepared 20-g methotrexate infusions in t he central pharmacy unit. We demonstrated that occupational safety dep ended not only on technical precautions, but on the skills of specific ally trained personnel.