Organic solvents are widely used in industry, and exposure to
them results in entry into the body through the skin as well as by
inhalation. Biological monitoring (BM) is a way of assessing
total exposure by all routes. Many BM methods currently
detect the compound of interest or its metabolites in blood or
urine. However, blood sampling is invasive, and requires
specially trained staff. Since there is a rapid exchange
between volatiles and gases in blood and air in the lungs, breath
sampling has been proposed as a non-invasive alternative to blood
sampling.
HSE Science and Research Centre has developed an
unique breath sampler (the Bio-VOC). The sampler
operation is such that it captures the final portion of an
exhalation, the end-tidal or alveolar air. This portion of
the exhaled air is in equilibrium with the blood passing
through the lungs. The captured portion of air is then transferred
onto a stainless steel tube packed with adsorbent material (the
same as used for ambient air monitoring). Once sealed, the
sample is robust for storage and transport at room temperature over
a number of weeks (unlike blood samples).
The solvent levels in the breath fall rapidly immediately after
exposure, followed by a relatively slower change in
excretion. This makes the technique only 'semi-quantitative'
for most solvents, although it can be used quantitatively for some
chlorinated solvents that are stored in body fat. The sample
is best taken in a 'clean' area (e.g. office, medical room) about
10 minutes after the end of exposure. Two, duplicate, samples
should be provided per worker per time point. Also, two tubes
should be returned unused, as 'field blanks'.
Breath sampling, like all biological monitoring, can be
especially useful when substances are potentially absorbed through
the skin (as many solvents are) and/or when control of exposure
relies upon personal protective equipment. By taking breath
samples, you can determine whether the control measures in place
are working or the PPE used is effective. It is also suitable for
following the effects of changing work practices or control
measures.
We designed and developed the Bio-VOC breath sampler, which is
now marketed by Markes International. You may either purchase the
Bio-VOC sampler to perform your own analyses or hire one from us
and have the analysis done for you.
Breath
sampling instructions
Loan of sampler and analysis
If you have no analytical testing facilities, we can loan the
breath sampler with the relevant sampling kit. You will be sent all
the necessary equipment and instructions. The loan of the sampler
is complimentary (you will be charged for sample analysis) but will
need to be returned.
Purchase of Bio-VOC samplers
If you have your own ATD facilities, you may purchase breath
samplers direct from Markes International (www.markes.com). Full
instructions will be provided.
Interpretation of results can be by a number of means: some
solvents (e.g. tetrachloroethene) have been set American or German
guidance values. Others can be interpreted from volunteer studies
or literature reviews. Many solvents will currently have to be
interpreted on an 'in-house' basis, by comparison to 'baseline'
values for particular processes. We have collated information
(including our own volunteer studies and field studies) for a
number of solvents to help interpret results (see below).