toluene - National Park Service

were significant differences between these two groups. At
higher concentrations of 2500 and 3500 ppm, the increase in
the free p-cresol levels was remarkable only in Donryu rats,
reaching the levels of Sprague-Dawley and Wistar rats, while
the level in Fischer rats remained unchanged. [Inoue O et al;
Bull Environ Contam Toxicol 43 (1): 74-9 (1989).
The mutual metabolic suppression between benzene and toluene
was studied. The subjects, 190 male Chinese workers employed
in shoe manufacturing, printing, audio equipment manufacture,
and automobile industries, were divided into four groups based
on occupational exposure: 65 were exposed to benzene, 35 to
toluene, 55 to both compounds, and 35 served as comparisons.
The arithmetic mean exposure level of benzene was 31.9 and of
toluene 44.7 ppm. The mixture contained benzene at 17.9 +/29.3
and toluene at 20.5 +/25.8 ppm. The exposure levels were
measured using individuals diffusive samplers. The geometric
mean levels of the metabolites, phenol, catechol,
hydroquinone, hippuric acid, and o-cresol, in unexposed
workers were 6.9, 9.4, 4.8, 72.5, and 0.066 mg per liter,
respectively. Values corrected for creatinine and specific
gravity were different from the values cited above. Multiple
correlation coefficients for benzene exposure versus its three
metabolites were for phenol, 0.740; for catechol, 0.629; and
for hydroquinone, 0.726. Multiple correlation coefficients for
toluene and its two metabolites were 0.649 for hippuric acid
and 0.583 for o-cresol. The slopes of regression lines for the
exposure to benzene in the presence of toluene were less than
half of those obtained when the workers were exposed to
benzene alone; however, the regression lines for benzene in
mixture versus catechol were about 80% or higher than the
lines observed with benzene as the sole pollutant. The
regression lines for toluene in the mixture and excretion
level of hippuric acid and o-cresol showed reduced metabolic
conversion compared to when exposure was limited to toluene
alone. It was concluded that simultaneous exposure to benzene
and toluene results in mutual suppression of metabolism
yielding the urinary metabolites phenol, hydroquinone,
hippuric acid, and o-cresol. [Inoue O et al; Int Arch Occup
Environ Health 60 (1): 15-20 (1988).
Water Data Interpretation, Concentrations and Toxicity (All Water
Data Subsections Start with "W."):
W.Low (Water Concentrations Considered Low):
No information found.
W.High (Water Concentrations Considered High):
Concentrations of 22 ug/L were recorded following a spill
into surface water [866].