The hydrolysis of cotton cellulose by hydrochloric acid in benzene

The partial hydrolysis of cotton cellulose by hydrogen chloride in benzene containing various proportions of water has been studied by measurements of fluidity, loss of weight, and copper number. Both the rate and site of hydrolysis are strongly dependent on the amount of water present. The determining factors are the partition of the hydrogen chloride between the water in the benzene and that adsorbed by the cellulose, and the relative accessibility of glycosidic linkages near the ends of chains and those far removed from chain ends. With little water present, hydrolysis tends to be confined to the ends of the cellulose chains.     

A quantitative approach to evaluate urinary benzene and S-phenylmercapturic acid as biomarkers of low benzene exposure

Context: Benzene is a ubiquitous pollutant; smoking habit, genetic polymorphisms, and analytical difficulties impact the identification of the best biomarker.

Objective: To apply a systematic quantitative approach to evaluate urinary benzene (BEN-U) and S-phenylmercapturic acid (SPMA) as biomarkers of low benzene exposures.

Methods: Seventy-one blue collar refinery workers, 97 white collar refinery workers and 108 general population subjects were included. Intrinsic characteristics, sampling and analytical issues were compared.

Results: BEN-U and SPMA were detected in 99% and 78% of samples, which correlated with benzene exposure (r?=?0.456 and r?=?0.636, respectively) and with urinary cotinine (r?=?0.630 and r?=?0.570, respectively). Intrinsic characteristics were similar for the two biomarkers: specificity (0.64 and 0.69 for BEN-U and SPMA), sensitivity (0.74 and 0.83), as well as intra- and inter-individual variability (150% and >14 for both).

Conclusion: BEN-U and SPMA show similar intrinsic characteristics; analytical issues in detecting SPMA suggest that BEN-U is more convenient for investigating low exposure levels.     

Polymerization of 10-hydroxydecanoic acid in benzene with polyethylene glycol-modified lipase

Summary A hydrophobic substrate, 10-hydroxydecanoic acid having two functional groups (–OH and –COOH) in the molecule, was polymerized by ester bond formation with the polyethylene glycol-modified lipase in a transparent benzene solution. The polymer of 10-hydroxydecanoic acid was linearly elongated under a quite mild condition.     

Activity of acid and alkaline phosphatase in neutrophils of rats exposed to benzene and treated with selenium.

Cytochemical studies on activity of acid phosphatase (AcP) and alkaline phosphatase (AP) in peripheral blood neutrophils of rats chronically exposed to benzene vapours (1,200 mg/cm3) demonstrated that the exposure results in the increase of AcP and the decrease of the AP activity. The changes noted correlate with the time of exposure and are observed even after 5 months after exposure. The administration of sodium selenate in a dose of 1.0 microgram/kg before exposure prevented the above enzymatic alterations caused by benzene. In contrast, the administration of selenium in a dose of 5.0 microgram/kg only prevented the change of AP activity and caused reactive neutrophilic leukocytosis.     

Detection of low level benzene exposure in supermarket wrappers by urinary muconic acid

Women who use the 'hot wire' and 'cool rod' machines to wrap meat in supermarkets are potentially exposed to low levels of benzene and polycyclic aromatic hydrocarbons present in fumes emitted during the thermal decomposition of the plastic used to wrap meat. In order to evaluate whether the benzene metabolite trans, trans-muconic acid (MA) can be used to monitor these low levels, we collected urine samples from supermarket workers, and assayed the urine for MA. Geometric mean after-shift MA levels were highest for subjects who used the 'hot wire' machine, i.e. > 300 ng mg-1 creatinine (Cr). The corresponding levels for subjects who used the 'cool rod' machine were similar to those for subjects who did not use either type of machine, and were much lower. These results indicate that urinary muconic acid has some potential for use in monitoring benzene exposures of less than 1 part per million (ppm). The study detected very high background MA levels (exceeding 2000 ng mg-1 Cr) in some subjects, suggesting that individuals in the general population without occupational exposure to benzene may have urinary MA levels equivalent to exposure to up to 2 ppm benzene in ambient air. However, since non-benzene sources of the metabolite cannot be completely ruled out as partially responsible for these high levels, the public health significance of this finding is not known at the moment.     

Detection of low level benzene exposure in supermarket wrappers by urinary muconic acid

Women who use the 'hot wire' and 'cool rod' machines to wrap meat in supermarkets are potentially exposed to low levels of benzene and polycyclic aromatic hydrocarbons present in fumes emitted during the thermal decomposition of the plastic used to wrap meat. In order to evaluate whether the benzene metabolite trans, trans-muconic acid (MA) can be used to monitor these low levels, we collected urine samples from supermarket workers, and assayed the urine for MA. Geometric mean after-shift MA levels were highest for subjects who used the 'hot wire' machine, i.e. > 300 ng mg-1 creatinine (Cr). The corresponding levels for subjects who used the 'cool rod' machine were similar to those for subjects who did not use either type of machine, and were much lower. These results indicate that urinary muconic acid has some potential for use in monitoring benzene exposures of less than 1 part per million (ppm). The study detected very high background MA levels (exceeding 2000 ng mg-1 Cr) in some subjects, suggesting that individuals in the general population without occupational exposure to benzene may have urinary MA levels equivalent to exposure to up to 2 ppm benzene in ambient air. However, since non-benzene sources of the metabolite cannot be completely ruled out as partially responsible for these high levels, the public health significance of this finding is not known at the moment.     

Initial steps in the degradation of benzene sulfonic acid, 4-toluene sulfonic acids,and orthanilic acid in Alcaligenes sp. strain O-1

Alcaligenes sp. strain O-1 grew with benzene sulfonate (BS) as sole carbon source for growth with either NH₄ ⁺ or NH₄ ⁺ plus orthanilate (2-aminobenzene sulfonate, OS) as the source(s) of nitrogen. The intracellular desulfonative enzyme did not degrade 3- or 4-aminobenzene sulfonates in the medium, although the enzyme in cell extracts degraded these compounds. We deduce the presence of a selective permeability barrier to sulfonates and conclude that the first step in sulfonate metabolism is transport into the cell. Cell-free desulfonation of BS in standard reaction mixtures required 2 mol of O₂ per mol. One mol of O₂ was required for a catechol 2,3-dioxygenase. When meta ring cleavage was inhibited with 3-chlorocatechol in desalted extracts, about 1 mol each of O₂ and of NAD(P)H per mol of BS were required for the reaction, and SO₃ ^2- and catechol were recovered in high yield. Catechol was shown to be formed by dioxygenation in an experiment involving ¹⁸O₂. 4-Toluene sulfonate was subject to NAD(P)H-dependent dioxygenation to yield SO₃ ^2- and 4-methylcatechol, which was subject to meta cleavage. OS also required 2 mol of O₂ per mol and NAD(P)H for degradation, and SO₃ ^2- and NH₄ ⁺ were recovered quantitatively. Inhibition of ring cleavage with 3-chrorocatechol reduced the oxygen requirement to 1 mol per mol of OS SO₃ ^2- (1 mol) and an unidentified organic intermediate, but no NH₄ ⁺, were observed.     

Effect of low concentration benzene vapor on metabolism of gamma-aminobutyric acid in brain mitochondrial fractions

The impact of benzene vapor (0.35 mg/l) of low concentration on the contents of free GABA, Glu and Asp, as well as on the enzyme activities of GDC and GABA-T in mitochondrial fractions of different brain regions of adult male rats was investigated. The conclusion was put forward that GABA increase by means of "keeping" inhibition provided for nerve cells defense from extremal excitation, taking place under the chronic exposure to the benzene low concentration.     

Mechanism of benzene toxicity. Effects of benzene and benzene metabolites on bone marrow cellularity,number of granulopoietic stem cells and frequency of micronuclei in mice

The effects of benzene and benzene metabolites (hydroquinone and catechol) on bone marrow cellularity, number of granulopoietic stem cells and on the frequency of micronuclei in polychromatic erythrocytes were investigated in mice. The dose-effect curve for benzene revealed that there was a threshold dose (approx. 100 mg benzene/kg body wt./day injected subcutaneously on 6 consecutive days) above which severe toxicity occurred in all three parameters. Also hydroquinone gave rise to adverse effects in the parameters studied, but the sequence of occurrence was different from that observed with benzene. These data are interpreted to indicate that hydroquinone is a hemotoxic metabolite of benzene in mice in vivo, but that other metabolites, or benzene itself, also probably contribute to the toxicity. Catechol gave no effects. However, due to acute effects like tremor and convulsions only rather low doses could be tested. Simultaneous administration of toluene dramatically reduced the toxicity of benzene, but gave only a small reduction of the hydroquinone-induced effects.