Identification of gases responsible for the odour of human flatus and evaluation of a device purported to reduce this odour

摘要

Background/Aims—Whilethe social significance of flatus derives mainly from its odour,previous studies have focused on the non-odoriferous components ofrectal gas. The aims of the present study were to determine the role ofsulphur-containing gases in flatus odour and test the efficacy of adevice purported to reduce this odour. 
Methods—Flatus wasquantitatively collected via rectal tube from 16 healthy subjects whoingested pinto beans and lactulose to enhance flatus output. Theconcentrations of sulphur-containing gases in each passage werecorrelated with odour intensity assessed by two judges. Odour intensitywas also determined after treatment of flatus samples with zincacetate, which binds sulphydryl compounds (hydrogen sulphide andmethanethiol), or activated charcoal. Utilising gas-tight Mylarpantaloons, the ability of a charcoal lined cushion to adsorbsulphur-containing gases instilled at the anus of eight subjects was assessed. 
Results—The mainsulphur-containing flatus component was hydrogen sulphide (1.06 (0.2)µmol/l), followed by methanethiol (0.21(0.04) µmol/l) anddimethyl sulphide (0.08 (0.01) µmol/l) (means (SEM)). Malodoursignificantly correlated with hydrogen sulphide concentration(p⩽0.001). Zinc acetate reduced sulphur gas content but did nottotally eliminate odour, while activated charcoal removed virtually allodour. The cushion adsorbed more than 90% of the sulphur gases. 
Conclusion—Sulphur-containinggases are the major, but not the only, malodorous components of humanflatus. The charcoal lined cushion effectively limits the escape ofthese sulphur-containing gases into the environment.