PT  - JOURNAL ARTICLE
AU  - M Døssing
AU  - J B Aelum
AU  - S H Hansen
AU  - G R Lundqvist
AU  - N T Andersen
TI  - Urinary hippuric acid and orthocresol excretion in man during experimental exposure to toluene.
AID  - 10.1136/oem.40.4.470
DP  - 1983 Nov 01
TA  - British Journal of Industrial Medicine
PG  - 470--473
VI  - 40
IP  - 4
4099  - http://oem.bmj.com/content/40/4/470.short
4100  - http://oem.bmj.com/content/40/4/470.full
SO  - Br J Ind Med1983 Nov 01; 40
AB  - It is not known whether urinary excretion of hippuric acid (HA) or orthocresol (O-Cr) is to be preferred for the biological monitoring of workers with occupational exposure to toluene. To study this, 42 printing trade workers with more than 10 years' exposure to a mixture of organic solvents including toluene (0-20 ppm) and 43 control subjects matched by age, smoking habits, and living accommodation were investigated. Each matched pair was randomised to an experimental exposure of either 100 ppm or 0 ppm toluene for 6.5 hours under controlled conditions in an exposure chamber. Urinary excretion of HA and O-Cr was determined by high pressure liquid chromatography from samples obtained before exposure, during the first three hours, and during the last 3.5 hours of exposure. No difference in HA and O-Cr excretion was found between printing trade workers and controls. The median O-Cr excretion increased 29 times during exposure, whereas the HA excretion increased only five times. Thus only 3% of the O-Cr excretion originated from other sources than toluene whereas the corresponding value for HA was 19%. Standardisation of the concentrations of HA and O-Cr in relation to urinary creatinine reduced the relative variation by 29% and 56% respectively. This was not reduced further by expressing the excretions as average excretion rates based on total volume of urine collected. Background urinary O-Cr excretion was three to four times higher among smokers than non-smokers, probably due to the content of O-Cr in cigarettes. The O-Cr excretion in unexposed smokers was, however, 10 times lower that that of the non-smokers during the end of the experimental exposure to 100 ppm toluene.