Handbook of Solvents - George Wypych - ChemTech - Ventech!

1088 Myrto Petreas
• The solvent is not metabolized to a great extent, and it is mainly eliminated via
exhalation.
• Sample collection is conducted in a location unaffected by ambient levels of the
solvent(s) of concern that may interfere and bias the measurements.
• The concentration in exhaled air is compatible with the analytical method allowing
adequate sensitivity.
• Appropriate timing is strictly followed.
15.2.1.7 Examples of breath monitoring
Two solvents are used to illustrate the use of breath monitoring in assessing solvent exposure:
A solvent with minimal metabolism, tetrachloroethylene (PERC) and a solvent with
significant metabolism, styrene. Both solvents are used extensively in industry with a great
number of workers potentially exposed. As shown in Table 15.2.1.2, styrene is only minimally
excreted through the lungs, whereas exhaled air is the major elimination route for
PERC. Accordingly, end-exhaled air is recommended as a BEI for PERC, but not for styrene.
Nevertheless, end-exhaled and mixed-exhaled air techniques have been studied in experimental
settings and in real-life occupational environments for both solvents. A
compilation of such studies is presented below.
Table 15.2.1.2. Characteristics of styrene and tetrachloroethylene (PERC).
[Information compiled from ACGIH, Documentation of Threshold Limit Values and
Biological Limit Values, 1991 7 ]
STYRENE PERC
Eliminated via lungs ~5% ~80-100%
Eliminated in the urine ~90% ~2%
Urinary metabolite(s)
Mandelic acid (MA),
Phenylglyoxylic acid (PA)
Trichloroacetic acid (TCA)
Blood/air partition coefficient (λ) 32-55 9-15
Pulmonary elimination
half-lives (T1/2) 13-52 min
4-20 hr
15 min
4 hrs
3 days
4 days
TLV (1998) 50 ppm 25 ppm
STEL (1998)
BEI (1998)
100 ppm 100 ppm
End-exhaled air
Not recommended
10 ppm end-of-shift, after at
least 2 shifts
Blood
0.55 mg/L end-of-shift 1 mg/L end-of-shift,
0.02 mg/L prior-to-next-shift after at least 2 shifts
Urine
TCA=7 mg/L
Major Industry
MA=800 mg/g creatinine,
end-of-shift
MA=300 mg/g creatinine,
prior-to-next-shift
PA=240 mg/g creatinine,
end-of-shift
PA=100 mg/g creatinine,
prior-to-next-shift
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