[Pollution of the work environment by volatile anesthetics and nitrous oxide]

Abstract

Anaesthetic personnel is exposed to different workload conditions. The individual impact is influenced by external factors and human stress stability. Different symptoms reported to be present in anaesthetic personnel are comparable to symptoms of the sick building syndrome, defined by the WHO in the 90's. They are caused by work-induced distress and the exposure to chemical hazards. In anaesthesia, health defects by anaesthetic vapours and gases have been deplored for many years. After the Russian anaesthesiologist Vaisman published a report in 1967, controlled studies concerning cancerogenicity and teratogenicity of volatile anaesthetics under workspace conditions were carried out. In 1989, time-weighted average exposure threshold limit values of 5 ppm were released in the Federal Republic of Germany for halothane. In 1993 thresholds for enflurane (20 ppm) and nitrous oxide (100 ppm) were released. TLV concentrations for the new anaesthetic agents desflurane and sevoflurane have not yet been defined by authorities. Factors influencing workplace concentrations of anaesthetic gases are the anaesthetic procedures, apparatus leakage, air conditioning, fresh gas flow and the function of the scavenging system. Although cancerogenicity, mutagenicity, teratogenicity and reduction of fertility are discussed as effects of chronic exposure to anaesthetic gases, several review articles doubted the results of studies, finding positive correlations of incidence of occupational disease and the exposure to the volatile and gaseous substances. Mainly coexisting factors like smoke-induced exposure to polybromated biphenyls, disturbance in circadian rhythm, stress and enclosure in narrow exposure systems, increasing teratogenicity and cancerogenicity in animal experiments, are considered to promote unreliability of the studies. All reviewers do not discuss the fact, that all of these co-factors are present in the reality of the anaesthetic workplace. Thus, the studies by Corbett, enthusiastically criticized by different reviewers, simulate the all-day reality of the anaesthetic workplace more precisely than controlled experiments conducted, for example, by Eger and co-workers. The results of animal experiments and retrospective studies therefore do not justify realization of large controlled prospective studies but require the overall revision of the anaesthesiological workplace and the reduction of occupational waste gas exposure to the lowest possible levels below all chronic exposure threshold values.