Exposure to anaesthetic gases and vapors in operating room personnel. Meta-analysis on miscarriage and congenital malformation risk

The interest about anaesthetic pollution in the operating room is linked to the toxic action of these substances and the associated health risk for all personnel chronically exposed. There are few recent studies about the miscarriage (AS) and congenital malformations (MC) risk in people exposed to inhalational anesthetics and most of them give different results. This work aims to make a meta-analysis in order to obtain an updated and comprehensive indication of the problem. Articles published in English or Italian since 1971 in Impact Factor or Indexed journals were systematically reviewed using PubMed and the Cochrane Library. Two researchers independently performed the research in September 2011 using specific Mesh Terms. The studies conducted in dentistry and veterinary setting were excluded. Data were analyzed through "IC Stata 12 for Macintosh" using the fixed-effect models of Mantel-Haenszel (MH) and Random-effect of DerSimonian & Laird (D&L). There were included 19 studies for the outcome AS (47,662 subjects) and 13 for the outcome MC (40,953 subjects). The value of overall relative risk for AS according to MH was 1.27 (CI 95%: 1.20-1.35) and according to D&L it was 1.311 (CI 95%: 1.20-1.43). However the included studies show heterogeneity (p=<0.02) and the publication bias was highlighted by a funnel plot. Similarly, for the MC, the global RR was 1.24 according MH is (CI 95%: 1.17-1.32) and according D&L it was 1.25 (CI 95%: 1.15-1.35), but the study results were more homogeneous (p=<0,17) and they show a minor publication bias. The meta-analysis highlights the existence of a small increased risk of AS and MC in the operating room personnel exposed continuously to low concentrations of inhaled anesthetics. However, this study underlines also a limited number of studies, especially about the new and more used halogenated anesthetics. Moreover the significant heterogeneity, the Publication Bias, besides the presence of additional risk factors and confounders (such as age, smoking habits, shift work, etc. ..) can affect the association with the analyzed outcomes. Overall this work suggests that this risk is close to zero in presence of careful management, monitoring and maintenance of the operating theater as well as a continuous operator training.