International archives of occupational and environmental health
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Int Arch Occup Environ Health · Mar 2003
Proposal for single and mixture biological exposure limits for sevoflurane and nitrous oxide at low occupational exposure levels.
Assessment of individual exposures to sevoflurane plus nitrous oxide (N(2)O) by biological monitoring of unmodified analytes in post-shift urine of exposed personnel. ⋯ Median (range) post-shift urinary and environmental values were 1.2 microg/l(urine) (0.1-5.0) and 0.4 ppm (0.05-3.0) for sevoflurane ( n=107) and 10.9 microg/l(urine) (0.5-74.9) and 8.6 ppm (0.2-123.4) for N(2)O ( n=121) (all low-exposure range). At log-log regression, urinary levels closely correlated with environmental data (sevoflurane, r(2)=0.7538; N(2)O, r(2)=0.8749). Biological equivalent limits (BELs) based on National Institute for Occupational Safety and Health (NIOSH) TWA exposure limits, calculated as means of regression slope and y-intercept, were 3.6 microg/l(urine) for sevoflurane (corresponding to 2 ppm) and 22.3 microg/l(urine) for N(2)O (corresponding to 25 ppm). Individual "mixture BELs", which we calculated by applying the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) mix formula to biomarker values and using the obtained NIOSH-based BELs as a reference, closely correlated with mixture TLVs (rho=0.816, Lin's concordance test). CONCLUSIONS. We propose urinary sevoflurane as a new, specific, internal dose biomarker for routine biological monitoring of personal exposures among operating-theatre personnel, and use of reliable "mixture BELs" to provide safer levels of internal exposure for workers exposed to mixtures of sevoflurane and N(2)O, and conceivably also to other mixtures of toxicants with possible additive effects.