title: Tale of two isomers: complexities of human odor perception for cis- and trans-4-methylcyclohexane methanol from the chemical spill in West Virginia.
abstract: Application of gas chromatography with mass spectrometric and human olfactory "sniffer" detectors reveals the nature of odorous chemicals from an industrial chemical spill. Crude 4-methylcyclohexane methanol (4-MCHM) spilled in a river and then contaminated drinking water and air for over 300000 consumers living in West Virginia. Olfactory gas chromatography allows investigators to independently measure the odor of chemical components in a mixture. Crude 4-MCHM is comprised of several major cyclohexane components, four of which have distinct isomer pairs. The cis- and trans-4-MCHM isomers are the only components to have distinct odors at the concentrations used in this study. The trans-4-MCHM is the dominant odorant with descriptors of "licorice" and "sweet". Trans-4-MCHM has an air odor threshold concentration of 0.060 ppb-v (95% CI: 0.040-0.091). The odor threshold concentrations are not influenced by gender or age but are lower by a factor of 5 for individuals with prior exposure compared to naïve subjects. Individual trans-4-MCHM odor threshold concentrations vary by more than a factor of 100. The cis-4-MCHM isomer has approximately a 2000-fold higher odor threshold concentration, different descriptors, and an even wider individual response range.
authors.affiliation: Civil and Environmental Engineering 413 Durham Hall, Virginia Tech , 1145 Perry Street, MC 0246, Blacksburg, Virginia 24061, United States.
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Gallagher
authors.forename: Katherine
authors.initials: K
authors.lastname: Phetxumphou
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Smiley
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Dietrich
mesh_terms: D000062:Accidents, Occupational; D000328:Adult; D000393:Air Pollutants / Q000032:analysis*; D003510:Cyclohexanes / Q000032:analysis*; D004787:Environmental Pollution; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007536:Isomerism; D008297:Male; D008875:Middle Aged; D009812:Odorants; D010465:Perception; D045483:Rivers / Q000737:chemistry; D012684:Sensory Thresholds; D012903:Smell; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014903:West Virginia; D055815:Young Adult
chemical_list: D000393:Air Pollutants; D003510:Cyclohexanes; D014874:Water Pollutants, Chemical