Article Text
Abstract
Aims: To compare environmental and biological monitoring of midwives for nitrous oxide in a delivery suite environment.
Methods: Environmental samples were taken over a period of four hours using passive diffusion tubes. Urine measurements were taken at the start of the shift and after four hours.
Results: Environmental levels exceeded the legal occupational exposure standards for nitrous oxide (100 ppm over an 8 hour time weighted average) in 35 of 46 midwife shifts monitored. There was a high correlation between personal environmental concentrations and biological uptake of nitrous oxide for those midwives with no body burden of nitrous oxide at the start of a shift, but not for others.
Conclusions: Greater engineering control measures are needed to reduce daily exposure to midwives to below the occupational exposure standard. Further investigation of the toxicokinetics of nitrous oxide is needed.
- midwifery
- nitrous oxide
- biological monitoring
- environmental monitoring
- occupational exposure
- TWA, time weighted average
- OES, occupational exposure standard