title: Effect of physical exertion on the biological monitoring of exposure to various solvents following exposure by inhalation in human volunteers: II. n-Hexane.
abstract: This study evaluated the impact of physical exertion on two n-hexane (HEX) exposure indicators in human volunteers exposed under controlled conditions in an inhalation chamber. A group of four volunteers (two women, two men) were exposed to HEX (50 ppm; 176 mg/m(3)) according to several scenarios involving several periods when volunteers performed either aerobic (AERO), muscular (MUSC), or both AERO/MUSC types of exercise. The target intensities for 30-min exercise periods separated by 15-min rest periods were the following: REST, 50W AERO [time-weighted average intensity including resting period (TWAI): 38W], 50W AERO/MUSC (TWAI: 34W), 100W AERO/MUSC (TWAI: 63W), and 100W AERO (TWAI: 71W) for 7 hr (two 3-hr exposure periods separated by 1 hr without exposure) and 50W MUSC for 3 hr (TWAI: 31W). Alveolar air and urine samples were collected at different time intervals before, during, and after exposure to measure unchanged HEX in expired air (HEX-A) and urinary 2,5-hexanedione (2,5-HD). HEX-A levels during exposures involving AERO activities (TWAI: 38W and 71W) were significantly enhanced (approximately +14%) compared with exposure at rest. MUSC or AERO/MUSC exercises were also associated with higher HEX-A levels but only at some sampling times. In contrast, end-of-exposure (7 hr) urinary 2,5-HD (mean +/- SD) was not modified by physical exertion: 4.14 +/- 1.51 micromol/L (REST), 4.02 +/- 1.52 micromol/L (TWAI 34W), 4.25 +/- 1.53 micromol/L (TWAI 38W), 3.73 +/- 2.09 micromol/L (TWAI 63W), 3.6 +/- 1.34 micromol/L (TWAI 71W) even though a downward trend was observed. Overall, this study showed that HEX kinetics is practically insensitive to moderate variations in workload intensity; only HEX-A levels increased slightly, and urinary 2,5-HD levels remained unchanged despite the fact that all types of physical exercise increased the pulmonary ventilation rate.
authors.affiliation: Groupe de recherche interdisciplinaire en santé, Département de santé environnementale et santé au travail, Université de Montréal, Québec, Canada. robert.tardif@umontreal.ca
authors.forename: Robert
authors.initials: R
authors.lastname: Tardif
authors.forename: Véronique
authors.initials: V
authors.lastname: Nadeau
authors.forename: Ginette
authors.initials: G
authors.lastname: Truchon
authors.forename: Martin
authors.initials: M
authors.lastname: Brochu
mesh_terms: D001944:Breath Tests; D004784:Environmental Monitoring; D015444:Exercise; D005260:Female; D006586:Hexanes / Q000032:analysis / Q000493:pharmacokinetics* / Q000633:toxicity; D006588:Hexanones / Q000652:urine; D006801:Humans; D019570:Inhalation Exposure / Q000032:analysis*; D007700:Kinetics; D008297:Male; D012997:Solvents / Q000032:analysis / Q000493:pharmacokinetics* / Q000633:toxicity
chemical_list: D006586:Hexanes; D006588:Hexanones; D012997:Solvents; C026385:n-hexane; C011269:2,5-hexanedione