Nitrous-oxide use. II. Risks, compliance, and exposure levels among Nebraska dentists and dental assistants.

This study measured nitrous oxide (N2O) exposure levels of 70 dentists and their dental assistants, and related these results to minutes of N2O use, compliance with N2O use guidelines, and risk of exposure. Dentists and dental assistants averaged, respectively, 97 and 59 parts per million (ppm) in N2O exposure, much higher than the recommended 25 to 50 ppm. Estimated peaks of exposure averaged 1,415 and 986 respectively for the two groups. Dentists exposure levels were significantly higher than those of dental assistants in both measures. Correlations revealed a significant link between compliance and estimated maximum exposure, and between minutes of use and 40-hour exposure readings. The variables most predictive of 40-hour N2O exposure were: minutes of use, frequency of use, number of operatories equipped, education of staff members on N2O health risks and exposure control, and operation of scavenging systems with the recommended liters/minute. This study established a feasible methodology for long-term, field-based epidemiological studies on N2O exposure, and identified some key variables related to 40-hour exposures and estimated maximum exposure.