Studies done in the 1960s on the risks of chronic exposure to waste anesthetic gases yielded conflicting results. A human study suggested an increased incidence of spontaneous abortion among female anesthesiologists, and an animal study showed that high concentrations of nitrous oxide could cause skeletal deformities in offspring. Subsequent publications supported the idea that waste anesthetic gases put anesthesia providers at risk for adverse health effects. In the 1970s, NIOSH recommended that waste anesthetic gases be scavenged and set recommended acceptable waste gas levels (Table 95.1). However, both prospective and epidemiologic studies conducted in the 1980s and 1990s have shown that, when scavenging is used to reduce amounts of volatile anesthetics to trace amounts, the waste gases pose no risk of adverse health effects. Also, health risks are not associated with short-term clinical (or unscavenged) exposure to potent volatile agents, such as isoflurane or sevoflurane. Experimental nitrous oxide exposure has been associated with animal reproductive abnormalities; however, these conditions do not exist for workers in the clinical environment in which scavenging is present. Of note, NIOSH transmitted its recommendation to the Occupational Safety and Health Administration (OSHA) in 1977. Since that time,
OSHA has not taken the necessary steps to promulgate the standards, but it has published technical instructions regarding waste gases. The Joint Commission on Accreditation of Healthcare Organizations has recommended that each anesthesia machine be equipped with a scavenging system and that monitoring be carried out.