Breath, urine, and blood measurements as biological exposure indices of short-term inhalation exposure to methanol

Abstract

Due to their transient nature, short-term exposures can be difficult to detect and quantify using conventional monitoring techniques. Biological monitoring may be capable of registering such exposures and may also be used to estimate important toxicological parameters. This paper investigates relationships between methanol concentrations in the blood, urine, and breath of volunteers exposed to methanol vapor at 800 ppm for periods of 0.5, 1, 2, and 8 h. The results indicate factors that must be considered for interpretation of the results of biological monitoring. For methanol, concentrations are not proportional to the exposure duration due to metabolic and other elimination processes that occur concurrently with the exposure. First-order clearance models can be used with blood, breath, or urine concentrations to estimate exposures if the time that has elapsed since the exposure and the model parameters are known. The 0.5 to 2-h periods of exposure were used to estimate the half-life of methanol. Blood data gave a half-life of 1.44+/-0.33 h. Comparable but slightly more variable results were obtained using urine data corrected for voiding time (1.55+/-0.67h) and breath data corrected for mucous membrane desorption (1.40+/-0.38 h). Methanol concentrations in blood lagged some 15-30 min behind the termination of exposure, and concentrations in urine were further delayed. Although breath sampling may be convenient, breath concentrations reflect end-expired or alveolar air only if subjects are in a methanol-free environment for 30 min or more after the exposure. At earlier times, breath concentrations included contributions from airway desorption or diffusion processes. As based on multicompartmental models, the desorption processes have half-lives ranging between 0.6 and 5 min. Preliminary estimates of the mucous membrane reservoir indicate contributions of under 10% for a 0.5-h exposure and smaller effects for longer periods of exposure.

Breath acetone analysis with miniaturized sample preparation device: In-needle preconcentration and subsequent determination by gas chromatography–mass spectroscopy

“…Exhaled human breath contains a large number of volatile organic compounds (VOCs), especially in low concentration, that related to their blood concentrations and vapor pressure [2,3]. Analysis of the exhaled breath is a non-invasive method for clinical purposes and much attention has been paid for the determination of particular compounds that might be a biomarker of several diseases [4][5][6].…”

Assessment of the cancer potential of methanol

“…The blood level is normally between 1 and 4 mg/L (Batterman and Franzblau, 1997;Batterman et al, 1998;Chuwers et al, 1995;Cook et al, 1991;Lee et al, 1992;Osterloh et al, 1996;Stegink et al, 1981). In the NEDO study, blood methanol was determined in an accompanying group of rats exposed for 4 weeks, similar to the rats in the main study.…”

Time-resolved cutaneous absorption and permeation rates of methanol in human volunteers

“…Recent estimates of elimination rates for methanol are con®ned to a small range (1.5±2 h half-life) (Batterman et al 1996c). This small range combined with the low sensitivity indicate that its uncertainty has no serious eect on results.…”

“…The derived absorption and delivery rates use subject-speci®c estimates of distribution volume V based on subject weight and scaled from the average individual given by Guyton (1994) as weighing 70 kg and having 40 l of body¯uids. A methanol half-life of 1.56 h (Batterman et al 1996c) was used.…”