The American Society of Anesthesiologists have a site regarding the hazards of waste anesthetic gases and the requirement to use a scavanging system to recover and exhaust these gases. And OSHA also has a site summarizing these waste anesthetic gases. Metofane is no longer available. Metofane substitutes . Isoflurane is not metaboloized to any great degree and is excreted primarily back out through the lungs.
Halothane can cause hypotension, decreased cardiac output, and respiratory depression.
Halothane also sensitizes the heart to catecholamines, which may lead to arrhymias.