Breath isoprene: temporal changes in respiratory output after
exposure to o3.
Foster, W. Michael, Long Jiang, Pamela T. Stetkiewicz, Terence H.
Risby.
Department of Environmental Health Sciences, School of Hygiene and
Public Health, The Johns Hopkins University, 615 North Wolfe Street,
Baltimore, MD 21205
APStracts 2:0500A, 1995.
Isoprene is a major hydrocarbon found in human breath. This study was
conducted to evaluate whether respiratory isoprene output could serve
as a monitor for ozone exposure. Healthy young adult subjects (n=10)
underwent chamber exposure on separate days to filtered air and a
variable concentration of ozone. Exposures had durations of 130 min
that included alternate periods of rest and light treadmill exercise;
breath was sampled pre- and post-exposure. For 6 subjects breath was
re-sampled 19+/-1 hr post-exposure. Breath samples were concentrated
cryogenically and analyzed by capillary gas chromatography. Isoprene
output, immediately post-exposure was significantly reduced by ozone
or filtered air, 17% and 19%, respectively. These results suggest
that exercise alone reduces isoprene levels in breath without an
additive ozone effect. However, in the 6 subjects re-studied 19+/-1
hr post-exposure to ozone, breath isoprene concentrations were now
increased above pre-exposure output by 99% (p<0.01), and
exceeded the 51% increase in output of isoprene at this time point
after filtered air exposure (p<0.01). Therefore breath isoprene
is proposed as a non-invasive marker of a physiological response to
oxidant-induced injury to epithelial membranes and fluid linings of
the lower respiratory tract by O3.
Received 19 June 1995; accepted in final form 6 November 1995.
APS Manuscript Number A644-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95