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A Comparative Study of the Kinetics and Bioavailability of Pure and Soil-Adsorbed Benzene, Toluene, and M-Xylene after Dermal Exposure
Published in Rhoda G. M. Wang, James B. Knaak, Howard I. Maibach, Health Risk Assessment, 2017
Mohamed S. Abdel-Rahman, Gloria A. Skowronski, Rita M. Turkall
The urinary metabolites of 14C-benzene, toluene, and m-xylene are presented in Table 6. Phenol was the major metabolite (38 to 46%) in the urine of all benzene groups. Smaller quantities of hydroquinone, catechol, and benzenetriol were also detected with hydroquinone significantly decreased in the 0 to 12-h collection period for the sandy soil group. In all toluene treatment groups, hippuric acid was the primary metabolite (63 to 72%), followed by a smaller amount of an undetermined metabolite (19 to 27%). No statistical differences were found between toluene treatments. Methylhippuric acid was identified as the major urinary metabolite (70 to 86%) in all m-xylene groups. Minor amounts of xylenol and the parent compound were also found. A statistically significant increase in xylenol occurred in the sandy soil group 12 h after dosing. Similar metabolite percentages were detected in the 12 to 24 and 24 to 48 h urine of all treatment groups for all three chemicals.
Organic Chemicals
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
In 1980, the annual production of xylene in the United States was 11.1 × 109 pounds.244 This production has steadily increased over the last 32 years. Xylenes are used for industrial cleaning, degreasing, processing, extracting, and thinning solvents.245 Mixed xylenes are used a diluents in the paint industry, in agricultural sprays for insecticides and in gasoline blends, synthetic resins, rubbers, and inks. Gasoline is about 9% xylenes by weight.246 Like toluene, xylenes causes CNS depression and can cause erythema, defatting dermatitis, conjunctivitis, renal damage, and paresthesia of the extremities. Xylene is metabolized by oxidation. It is then conjugated to methylhippuric acid and excreted in the urine. It has half-life of 20–30 hours, except in the chemically sensitive, where it may linger for weeks. Only about 5% of xylene is exhaled unchanged.
Hepatotoxicological potential of P-toluic acid in humanised-liver mice investigated using simplified physiologically based pharmacokinetic models
Published in Xenobiotica, 2021
Tomonori Miura, Yusuke Kamiya, Shotaro Uehara, Norie Murayama, Makiko Shimizu, Hiroshi Suemizu, Hiroshi Yamazaki
Estimation of the human exposures to synthetic chemicals by biomonitoring is an important research area in health science (Sexton et al.2006, Alwis et al.2012). Xylenes (or dimethylbenzenes) are used as organic solvents in various industrial preparations (Lauwerys and Buchet 1988, Marchand et al.2015). In humans, the urinary excretion of xylene metabolites such as methylhippuric acid (Figure 1) has been studied in volunteers under experimental exposures and in workers under occupational exposures (Ogata et al.1970, Kawai et al.1991, Inoue et al.1993). Methylhippuric acid is biotransformed from toluic acid by glycine conjugation in rodents and humans. These glycine conjugations generally proceed in two-step reactions and are mediated by bile acid CoA:amino acid N-acyltransferase (Kwakye et al.1991, Falany et al.1997). Rodent preparations reportedly show more rapid glycine conjugation in vitro than human preparations (Kirkpatrick et al.1988, Hewitt et al.2001, Gu et al.2007). It should be noted that the no‐observed‐effect level (NOEL) of p-toluic acid in rats is high (1000 mg/kg) (Sakuratani et al.2013), possibly because of the rapid glycine conjugation of p-toluic acid and that no lowest observed effect level has been recorded in rats. Among potential animal models (including rodents), choosing the most appropriate species is relatively complex because some species may be better metabolically suited to a particular line of research than others (Wetmore et al.2010).
Distortion product otoacoustic emission sensitivity to different solvents in a population of industrial painters
Published in International Journal of Audiology, 2020
Renata Sisto, Luigi Cerini, Filippo Sanjust, Damiano Carbonari, Monica Gherardi, Andrea Gordiani, Nunziata L’Episcopo, Enrico Paci, Daniela Pigini, Giovanna Tranfo, Arturo Moleti
The measure of the exposure to organic solvents, in particular, styrene, toluene, xylene, has been performed during the work shift by means of both personal airborne exposure evaluation techniques and biological monitoring. The biological monitoring was performed by measuring, before and at the end of the work-shift, the urinary concentration of Methylhippuric acid (MHIPPA, xylenes metabolite), PGA and MA (ethylbenzene metabolites), S-benzyl mercapturic acid (SBMA, toluene metabolite) and S-phenylmercapturic acid (SPMA, benzene metabolite). The products of DNA and RNA oxidation excreted into urine are biomarkers of oxidative damage in humans. The 8-oxo-7,8-dihydroguanine (8-oxoGua), 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo) urinary concentrations were measured as biomarkers of oxidative stress induced by the working task and, in particular, by the exposure to solvents.
Impaired neuromuscular function by conjoint actions of organophosphorus insecticide metabolites omethoate and cyclohexanol with implications for treatment of respiratory failure
Published in Clinical Toxicology, 2021
Kosala N. Dissanayake, Robert Chang-Chih Chou, Adrian Thompson, Filip Margetiny, Charlotte Davie, Scott McKinnon, Vishwendra Patel, Lester Sultatos, Joseph J. McArdle, Richard E. Clutton, Michael Eddleston, Richard R. Ribchester
Cyclohexanol is normally metabolised further and the products then excreted, as 1,2- and 1,4-cyclohexanediols [28,65]. Xylene, another common solvent in agricultural insecticide formulations and which the data in Figure 9 show also impairs neuromuscular function, is normally metabolised then excreted as methyl hippuric acid [66]. Establishing whether these other solvent metabolites also inhibit normal neuromuscular transmission and function in vivo and clinically could prove important for generalising our conclusions regarding toxicity of solvents or their metabolites that we have shown here.