Is routine blood test of value for evaluating health effects among midwives working with nitrous oxide for pain relief in delivery unit

Abstract

Chronic workplace exposure to high nitrous oxide concentrations has been suggested to potentially be associated to negative health effects caused by the interference with the vitamin B12, methionine synthase pathway. The objective of the present study was to determine if delivery unit work place ambient air nitrous oxide exposure results in detectable hyperhomocysteinemia or signs of macrocytocis in personnel. Blood samples from thirty healthy female fulltime employees, midwives, aged 43 (range 25-62) years were studied. Routine blood test analysed for plasma homocysteine and blood status; haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin concentration, blood status was analysed once before going on vacation and repeated after at least 10 days’ leave, nitrous oxide free period. Median time weighted average was 41 [10 - 547] ppm; 3 out of 11 TWA measurements were above recommended100 ppm limit. Median homocysteine concentrations were 10.7 [5.6 - 16] micromol/L with reference limits of 5.0 – 15 micromol/L. Megaloblastic erythrocytes was not detected in any personnel and no changes in blood status could be detected between before and after a nitrous oxide-free period. Conclusions: One of 3 delivery units’ ambient air quality measures exceed recommended ranges. No signs of routine blood test pathology could be seen in the personnel studied.