Passive and Active Sampling of Occupational Exposures to Nitrous Oxide Among Indian Health Service Dental Employees and Possible Mitigating Factors

Nitrous oxide is a commonly used gas in dental facilities and considered safe for patients undergoing dental procedures. However, epidemiological studies show that there are adverse health effects associated with chronic occupational exposure to nitrous oxide, including reproductive issues, neurologic, renal and liver disease. Indian Health Service reports have documented high levels of nitrous oxide during dental procedures. This study compared sampling using the Thermo ScientificTM Miran SapphIRe portable analyzer with the Advanced Chemical Sensor Passive Badge, and characterized dental personnels exposure to nitrous oxide levels in the breathing zones during dental procedures. Similar exposure groups were determined by job title Dentist and Dental Assistant and an ANOVA was used to explore the appropriateness of considering similarity of the groups across 6 dental clinics within the Indian Health Service. An independent t- test was used to determine if there was a mean difference of exposure between the similar exposed groups. A paired t-test was used to compare the similarity of the two sampling methods, and the Bland-Altman analysis was used to assess level of agreement between the two methods. Finally, this study looked at the effect of nitrous oxide concentrationflow rate and room air exchange rates on exposure levels. Excursion levels over the occupational exposure limit of 250 ppmv were exceeded in 21 of 41 51 procedures in this study. Mean upper tolerance limit estimates for dental procedures were 1245 ppmv for dentists and 802 ppmv for dental assistants. Four passive 8-hour TLV-TWAs were over the 50 ppmv occupational exposure limit, two for dentists 55.6 and 152 ppmv and two for dental assistant 81.3 and 56.0 ppmv. There was no significant difference between similar exposure group concentrations using either sampling method Miran SapphIRe portable analyzer, 0.071 Advanced Chemical Sensor Passive Badge, p-value 0.106.