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At least 19 recordsLinked to original sources
PubMed1992

Metabolites formed during anaerobic transformation of toluene and o-xylene and their proposed relationship to the initial steps of toluene mineralization.

Strain T1 is a facultative bacterium that is capable of anaerobic toluene degradation under denitrifying conditions. While 80% of the carbon from toluene is either oxidized to carbon dioxide or assimilated into cellular carbon, a significant portion of the remainder is transformed into two dead-end metabolites. These metabolites were produced simultaneous to the mineralization of toluene and were identified as benzylsuccinic acid and benzylfumaric acid. Identification was based on comparison of mass spectra of the methyl esters of the metabolites and authentic compounds that were chemically synthesized. Strain T1 is also capable of o-xylene transformation during growth on toluene. o-Xylene does not serve as a source of carbon and is not mineralized. Rather, it is transformed to analogous dead-end metabolites, (2-methylbenzyl)-succinic acid and (2-methylbenzyl)-fumaric acid. o-Xylene transformation also occurred during growth on succinic acid, which suggests that attack of the methyl group by succinyl-coenzyme A is a key reaction in this transformation. We reason that the main pathway for toluene oxidation to carbon dioxide involves a mechanism similar to that for the formation of the metabolites and involves an attack of the methyl group of toluene by acetyl-coenzyme A.

Anaerobiosis↗
PubMed1992

Microbial degradation of toluene under sulfate-reducing conditions and the influence of iron on the process.

Toluene degradation occurred concomitantly with sulfate reduction in anaerobic microcosms inoculated with contaminated subsurface soil from an aviation fuel storage facility near the Patuxent River (Md.). Similar results were obtained for enrichment cultures in which toluene was the sole carbon source. Several lines of evidence suggest that toluene degradation was directly coupled to sulfate reduction in Patuxent River microcosms and enrichment cultures: (i) the two processes were synchronous and highly correlated, (ii) the observed stoichiometric ratios of moles of sulfate consumed per mole of toluene consumed were consistent with the theoretical ratio for the oxidation of toluene to CO2 coupled with the reduction of sulfate to hydrogen sulfide, and (iii) toluene degradation ceased when sulfate was depleted, and conversely, sulfate reduction ceased when toluene was depleted. Mineralization of toluene was confirmed in experiments with [ring-U-14C]toluene. The addition of millimolar concentrations of amorphous Fe(OH)3 to Patuxent River microcosms and enrichment cultures either greatly facilitated the onset of toluene degradation or accelerated the rate once degradation had begun. In iron-amended microcosms and enrichment cultures, ferric iron reduction proceeded concurrently with toluene degradation and sulfate reduction. Stoichiometric data and other observations indicate that ferric iron reduction was not directly coupled to toluene oxidation but was a secondary, presumably abiotic, reaction between ferric iron and biogenic hydrogen sulfide.

Biodegradation, Environmental↗
PubMed1992

Influence of various mixtures of inhaled toluene and xylene on the biological monitoring of exposure to these solvents in rats.

The present study was undertaken to describe the influence of simultaneous exposure by inhalation to toluene and xylene on some aspects of their respective metabolic disposition. Adult male rats were exposed acutely (5 h) to 75, 150, and 225 ppm of toluene or xylene and to various mixtures of these solvents: toluene (75 ppm) and xylene (225 ppm), toluene (150 ppm) and xylene (150 ppm), toluene (225 ppm) and xylene (75 ppm). Compared with single exposure, simultaneous exposure resulted in lower amounts of excreted hippuric acid (20-30%) and methylhippuric acids (4-40%) in urine over a period of 24 h, even though significant differences were seen only with the toluene (150 ppm) and xylene (150 ppm) combination. In addition, increased concentrations of solvents in blood (toluene, 230%; xylene, 500%) and in brain (toluene, 230%; xylene, 320%) were found during the immediate post-exposure period. Simultaneous exposure also enhanced the pulmonary elimination of both solvents (toluene, 190-240%; xylene, 340-650%). Influence of repeated simultaneous exposure (9 days) was investigated for the toluene (150 ppm) and xylene (150 ppm) combination and the results compared with those of repeated exposure to each solvent administered singly. Under these conditions, repeated simultaneous exposure decreased the excretion of urinary metabolites, but only after the first exposure. On the other hand, simultaneous exposure resulted in significantly higher concentrations of toluene (210%) and xylene (240%) in blood throughout the entire 9-day exposure period. These results strongly suggest mutual metabolic interactions (inhibition) between toluene and xylene that affect the metabolic disposition of both solvents and ultimately the biological monitoring of data of exposure to a combination of solvents in rats.

Administration, Inhalation↗
PubMed1992

Effects of ethanol and phenobarbital treatments on the pharmacokinetics of toluene in rats.

Rats were exposed to toluene at a wide range of concentrations from 50 to 4000 ppm for six hours, and the effects of ethanol and phenobarbital (PB) treatments on the pharmacokinetics of toluene metabolism were investigated. Ethanol treatment influenced toluene metabolism mainly at low exposure concentrations. Thus ethanol accelerated the clearance of toluene from blood only when the blood concentration of toluene was not high (less than 360 microM), and ethanol increased hippuric acid (HA) excretion in urine more significantly at low (less than 250 ppm) than at high atmospheric toluene concentrations. Ethanol also expressed a similar effect on p-cresol excretion as on HA, but had little effect on o-cresol. Phenobarbital treatment promoted the urinary excretion of all of the metabolites of toluene, especially after exposure to high toluene concentration. As well as HA, benzoylglucuronide (BG) and free benzoic acid were found in urine. These are the products of the side chain metabolism of toluene. Amounts of BG could be detected when the urinary excretion of free benzoic acid exceeded 5 mumol/kg/6 h, indicating that a great deal of benzoic acid is required for the formation of BG. The Michaelis constant (Km) and the maximum rate of metabolic excretion in urine during six hours exposure (Vmax) of isozymes involved in the excretion of toluene metabolites were calculated, and correlated with the subtypes of cytochrome P-450. The significance of the result was suggested in the biological monitoring of exposure to toluene.

Animals↗
PubMed1975

Permanent loss of chromosome initiation in toluene-treated Bacillus subtilis cells.

Initiation of deoxyribonucleic acid replication is absent in Bacillus subtilis cells made permeable by toluene. The absence of initiation may be (i) a temporary removal of toluene, or (ii) irreversibly lost due to damage by toluene treatment to a cellular structure or a process required for chromosome initiation. Washed cells, previously treated with toluene and subsequently washed free of detectable amounts of toluene, have the same characteristics of toluene-treated cells in which toluene is not removed. The continued absence of initiation in the washed cells indicates a permanent loss of initiation in cells treated with toluene. Protein synthesis is also inhibited irreversibly by toluene treatment, indicating damage to translation as a possible mechanism for loss of initiation of toluene-treated cells.

Bacillus subtilis↗
PubMed1977

The neurotoxicity of toluene: EEG changes in rats exposed to various concentrations.

Workers exposed to toluene develop many central and autonomic nervous symptoms. It has been suggested that the effects of toluene on the central nervous system may be detectable by EEG. In the present experiments, changes in EEG and behaviour of rats exposed to toluene were monitored in an attempt to clarify the relationship between exposure to toluene and central nervous system reaction. Chronically implanted electrodes were used in Wistar albino male rats to record EEG in cortex and hippocampus, cervical EEG and pulse rate. The rats were exposed to 4000 ppm, 2000 ppm and 1000 ppm toluene vapour for four hours. The sleep cycle was divided into five phases (wakeful, spindle, slow-wave, preparadoxical and paradoxical) judged by the cortical and hippocampal EEGs, the cervical EMG, and behaviour. This classification should be useful in assessment of the effects of toluene on the central nervous system. In our experiments, the changes in the sleep cycle suggest that 4000 ppm and 2000 ppm of toluene vapour disturb the sleep, and 1000 ppm of toluene vapour prevents sleep entering the slow-wave phase but facilitates its entry into the paradoxical phase. The changes of EEG components were peculiar to each concentration. The results suggest, in effect, that analysis of the changes in the EEG components would be helpful as an index to the reaction of the central nervous system to toluene vapour.

Animals↗
PubMed1978

The effect of toluene on the structure and permeability of the outer and cytoplasmic membranes of Escherichia coli.

The effect of toluene on Escherichia coli has been examined. In the presence of Mg2+, toluene removes very little protein, phospholipid, or lipopolysacharide from E. coli. In the absence of Mg2+, or in the presence of EDTA, toluene removes considerably more cell material, including several specific cytoplasmic proteins such as malate dehydrogenase (EC 1.1.1.37). In contrast, glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and glutamate dehydrogenase (EC 1.4.1.4) are not released at all under the same conditions. Cells treated with toluene in the presence of Mg2+ remain relatively impermeable to pyridne nucleotides, while cells treated with toluene in the presence of EDTA become permeable to these compounds. Freeze-fracture electron microscopy shows that toluene causes considerable damage to the cytoplasmic membrane, while the outer membrane remains relatively intact. These results indicate that the permeability characteristics of toluene-treated cells depend at least partly on the state of the outer membrane after the toluene treatment.

Cell Membrane↗
PubMed1977

Exposure of animals and man to toluene.

Twenty rats were exposed for 60 min to 14C-labeled toluene (1,950 mg/m3) in the inspired air. The largest amounts of toluene and its metabolites were found in the white adipose tissue. In a second series of experiments seven healthy male subjects were exposed to 375 mg/m3 of toluene in the air rest and during light, moderate and heavy physical exercise on a bicycle ergometer. The duration of each exposure period was 30 min. Of the seven male subjects three were thin, one was slightly overweight, and three were excessively overweight. The concentration of toluene in the alveolar air and the total uptake of toluene were determined during exposure. The thin subjects had a higher concentration of toluene in alveolar air than the other subjects both at rest and during exercise. The total uptake of toluene in the body during exposure showed that the subjects with the least amount of adipose tissue had the smallest uptake and the subjects with the largest amount of adipose tissue had the largest uptake.

Adipose Tissue↗
PubMed1992

Interactive effects of toluene and hexane on behavior and neurophysiologic responses in Fischer-344 rats.

Solvent mixtures are ubiquitous in industrialized environments and are used frequently for recreational purposes. Toluene and hexane are common components of many solvent mixtures and have characteristic, but different, neurotoxic consequences. Interestingly, Takeuchi et al., (1981) reported that toluene attenuated the peripheral neuropathy caused by n-hexane, possibly by blocking its metabolism to 2,5-hexanedione (Perbellini, et al., 1982). To confirm such effects at higher concentrations and to examine effects on the central nervous system (CNS), four groups of 12 rats each were exposed to air, toluene (1200 ppm), hexane (4000 ppm), or a mixture of toluene (1200 ppm) and hexane (4,000 ppm) 14 hr/day for 9 weeks. A battery of behavioral and electrophysiologic tests was used to assess the functional consequences of their exposures. The battery consisted of measures of grip strength, locomotor gait and landing splay, sensory sensitivities during conditioned avoidance performance, the action potential of the ventral caudal nerve, and the brainstem auditory evoked response. Measures of peripheral nervous system functions (e.g., grip strength and conduction velocity) showed interactive effects like those reported by Takeuchi et al. Toluene greatly reduced the neuropathy caused by hexane. Hexane-induced abnormalities in central components of the brainstem response were much less reduced in the presence of toluene. There was no reciprocal action of hexane on the motor syndrome and hearing loss caused by toluene.

Action Potentials↗
PubMed1992

Sex-, age- and pregnancy-induced changes in the metabolism of toluene and trichloroethylene in rat liver in relation to the regulation of cytochrome P450IIE1 and P450IIC11 content.

Sex-, age- and pregnancy-induced changes in the metabolism of toluene and trichloroethylene in rat liver were investigated in relation to the regulation of cytochrome P450IIE1 and P450IIC11 content using monoclonal antibodies. Immature male rats had a higher level of microsomal protein than females, and this increased with development; however, no difference by sex was found at puberty. No difference in cytochrome P450 content was seen between immature male and female rats; the content increased with development only in males, so that a sex difference in cytochrome P450 content occurred at puberty. Pregnancy decreased the cytochrome P450 content but not that of the microsomal protein. The rate of formation of benzyl alcohol from toluene was 4 times higher in mature than in immature male rats at a high concentration of toluene, but no difference was seen at a low toluene concentration. In contrast, the rate was lower in mature female rats than in immature ones at a low toluene level and no difference was seen at the high concentration. A sex difference was thus found in benzyl alcohol formation at puberty at both concentrations of toluene. The levels of o- and p-cresol formation in liver were similar in males and females but the rate decreased during development of females. The rate of metabolism of trichloroethylene was higher in immature than in mature male and female rats, especially at a low substrate level, and no sex difference in metabolism was seen with either age or concentration of trichloroethylene. Pregnancy decreased the metabolism of both toluene and trichloroethylene.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1992

Regional brain distribution of toluene in rats and in a human autopsy.

Toluene concentrations in 9 brain regions of acutely exposed rats and that in 11 brain regions of a human case who inhaled toluene prior to death are described. After exposure to toluene by inhalation (2000 or 10,000 ppm) for 0.5 h or by oral dosing (400 mg/kg), rats were killed by decapitation 0.5 and 4 h after onset of inhalation and 2 and 10 h after oral ingestion. After each experimental condition the highest range of brain region/blood toluene concentration ratio (BBCR) was in the brain stem regions (2.85-3.22) such as the pons and medulla oblongata, the middle range (1.77-2.12) in the midbrain, thalamus, caudate-putamen, hypothalamus and cerebellum, and the lowest range (1.22-1.64) in the hippocampus and cerebral cortex. These distribution patterns were quite constant. Toluene concentration in various brain regions were unevenly distributed and directly related blood levels. In a human case who had inhaled toluene vapor, the distribution among brain regions was relatively similar to that in rats, the highest concentration ratios being in the corpus callosum (BBCR: 2.66) and the lowest in the hippocampus (BBCR: 1.47).

Adult↗
PubMedDate not supplied

Urinary ortho-cresol concentrations as an indicator of toluene inhalation in glue-sniffers.

In a Japanese study of glue-sniffers, urinary ortho-cresol and expired air toluene concentrations were determined by gas chromatography, and urinary hippuric acid concentrations by high performance liquid chromatography. There were significant differences among three sample groups (30 male "glue-sniffers", 13 "non-glue-sniffers" and 32 industrial workers) in their expired air toluene, urinary hippuric acid and ortho-cresol concentrations. Moreover, there was a better correlation between expired air toluene and urinary ortho-cresol concentrations than between toluene and urinary ortho-cresol concentrations than between toluene and hippuric acid. These results suggest that urinary ortho-cresol is a good indicator of toluene inhalation in glue-sniffers.

Adolescent↗
PubMed1978

Embryotoxic effects of benzene and its methyl derivatives: toluene, xylene.

CFY rats were exposed to inhalation of 1000 mg/m3 (313ppm) benzene, 1500 mg/m3 (399 ppm) toluene, or 1000 mg/m3 (230 ppm) xylene for 24 h/day from day 9 to day 14 of pregnancy; to that of 1500 mg/m3 (399 ppm) toluene for 24 h/day from day 1 to day 8 of pregnancy, or 1000 mg/m3 (266 ppm) toluene for 8 h/day from day 1 to day 21 of pregnancy,. CFLP mice were exposed to inhalation of 500 mg/m3 (133 ppm) toluene for 24 h/day from day 6 to day 13 of pregnancy. Untreated animals and groups inhaling pure air served as controls. None of the solvents proved to be teratogenic, the incidence of malformations did not change as a result of exposure, though an increase in skeletal anomalies (extra ribs, fused sternebrae) was observed with all 3 solvents. Benzene and toluene also caused considerable retardation of fetal development. The growth retarding effect of toluene on fetal development in early pregnancy is of particular importance from the point of view of occupational hygiene.

Animals↗
PubMed1992

Auditory sensitivity in rats exposed to toluene and/or acetyl salicylic acid.

The present study investigates whether exposure to acetyl salicylic acid (ASA) affects the permanent auditory loss, caused by simultaneous exposure to toluene. Rats were exposed to toluene by inhalation (1,000 ppm), or to ASA by gavage (100 mg kg-1), or to both toluene and ASA, during 10 days. Toluene exposure caused a loss of auditory sensitivity recorded as auditory brainstem response, and no loss was found after exposure to ASA alone. The group exposed to both ASA and toluene had a more severe sensitivity loss (p < 0.05) at all frequencies compared with all other groups immediately after (2-5 days) exposure and also 4 months later. The results indicate that ASA permanently potentiates toluene induced loss of auditory sensitivity.

Acoustic Stimulation↗
PubMed1992

Menstrual function in workers exposed to toluene.

Rates of menstrual disorders were studied in 231 female production workers with high exposure to toluene (mean 88 (range 50-150 ppm) in a factory manufacturing audio speakers and compared with a control group of 58 female production workers in other departments in the same factory who had little or no exposure to toluene (0-25 ppm). An external community control group of 187 working class women under routine care at public maternal and child health centres were also studied. Detailed menstrual and reproductive histories were obtained by personal interview using a structured questionnaire. The rates for dysfunctional uterine bleeding (cycle irregularity and prolonged or heavy menstrual bleeding) were similar in all groups. Dysmenorrhoea seemed to occur more often in the women highly exposed to toluene compared with women at maternal and child health centres, but not compared with factory controls with low exposure to toluene. There was no evidence that dysfunctional uterine bleeding was likely to result from exposure to toluene. It is uncertain whether dysmenorrhoea was associated specifically with exposure to toluene, as other behavioural and work related factors may also result in dysmenorrhoea.

Adult↗
PubMed1977

Longitudinal study of workers employed in the manufacture of toluene-diisocyanate.

Workers at a toluene-diisocyanate manufacturing plant were studied longitudinally to determine the effects of the chemical on their health. Studies included health questionnaire, pulmonary function, environmental monitoring, and immunologic testing. Workers reporting increased lower respiratory symptoms were from the nonsmoker group. Environmental monitoring showed frequent excursions of toluene-diisocyanate concentrations above the threshold limiting value. There was poor correlation between area and personal exposure levels. No exposure-related decline of pulmonary function was demonstrable. Immunologic studies showed development of a positive skin test to a toluene-diisocyanate-human serum albumin conjugate by some persons and an increasing incidence of toluene-diisocyanate-specific IgE antibodies as measured by a radioallergosorbent test. Toluene-diisocyanate did not induce histamine release from leukocytes in vitro but did diminish the in vitro stimulation of cyclic adenosine monophosphate by isoproterenol. Most of the clinically sensitive persons demonstrated adverse bronchial response when challenged by inhalation of toluene-diisocyanate. This response was dose dependent in some persons. When challenged with Mecholyl, clinically sensitive persons showed greater reactivity of airways than nonsensitive persons.

Antibodies↗
PubMed1978

Effect of single exposure to toluene on Sidman avoidance response in rats.

Effects of single exposure to toluene on Sidman avoidance response in rats were studied. The animals, in which the behavioral base line had been established, were exposed 0, 1,000 and 3,000 ppm of toluene vapor for 4 hours and the effects on the behavioral pattern were investigated using Sidman avoidance test for one hour after the termination of toluene exposure. 1) Exposure to 0 or 1,000 ppm of toluene did not produce marked change on the operant behavior. After the exposure to 3,000 ppm, the animals produced increased responses with shortening of the inter-response-time (IRT) and no changes in shock counts from the beginning to the 50 min. zone of the Sidman avoidance test when compared with those before exposure. The behavioral change indicated here appears to be caused by a temporary breakdown of the established timing of lever pressing. 2) The effect of toluene on the operant behavior was strongest immediately after the termination of the exposure and the behavior recovered in about an hour. This result suggested that toluene is rapidly transfered to and removed from the brain.

Animals↗