Organic Chemicals
William J. Rea, Kalpana D. Patel in Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
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.
Pharmacokinetic/Physiologically Based Pharmacokinetic Models in Integrated Risk Information System Assessments
John C. Lipscomb, Edward V. Ohanian in Toxicokinetics and Risk Assessment, 2016
A UF of 10 was applied for intraspecies uncertainty to account for human variability and sensitive populations. The degree of human variance in abilities to absorb or dispose of xylenes is unknown, as is the degree of human variance in responding to xylene’s neurotoxicity. Results from developmental toxicity studies of rats exposed by inhalation during gestation indicate that adverse developmental effects occur only at doses higher than chronic doses producing the critical effects observed in adult male rats in the principal and supporting studies, suggesting that the developing fetus is not at special risk from low-level exposure to xylenes. However, as with oral exposure, the effects of inhaled xylenes in other potentially sensitive populations such as newborns or young children or animals have not been assessed.
Hydrocarbons*
Bev-Lorraine True, Robert H. Dreisbach in Dreisbach’s HANDBOOK of POISONING, 2001
Benzene: liquid; bp: 80°C; vapor pressure at 26°C: 100 mmHg; exposure limit: 1 ppm. Xylene: commercial preparation a mixture of o-, m-, p-; bp: 140°C; vapor pressure at 28°C: 10 mmHg; exposure limit: 100 ppm. Toluene: liquid; bp: 110°C; vapor pressure at 31°C: 40 mmHg; exposure limit: 100 ppm. Coal tar naphtha is a mixture of benzene, toluene, xylene, and other aromatic hydrocarbons.
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).
Update on proteomic studies of formalin-fixed paraffin-embedded tissues
Published in Expert Review of Proteomics, 2019
Laura Giusti, Cristina Angeloni, Antonio Lucacchini
Deparaffinization is the first step in the approach with FFPE tissues and consists in the solubilization of paraffin with different apolar organic solvents or mineral oils (see [1]). Rehydration process is carried out with alcohol (methanol or ethanol) at decreasing concentration. Xylene is the apolar solvent most widely used still today, despite its toxicity, followed by rehydration with ethanol. Recently the use of efficient xylene free protocols for paraffin solubilization was proposed by three different research groups [9–11] utilizing hot water (95°, 90°, 80°C, respectively) for protein extraction or DNA extraction. The authors suggested that these protocols have the advantage to avoid toxic xylene and to perform solubilization and rehydration at the same time reducing the time of deparaffinization.
Enhancement of ocular anti-glaucomic activity of agomelatine through fabrication of hyaluronic acid modified-elastosomes: formulation, statistical optimisation, in vitro characterisation, histopathological study, and in vivo assessment
Published in Journal of Microencapsulation, 2023
Asmaa Ashraf Nemr, Galal Mohamed El-Mahrouk, Hany Abdo Badie
Six male albino rabbits were utilised during the histopathological test. The rabbits were split into groups (A and B), with three rabbits in each group, and visually examined before initialising the study to exclude rabbits with any inflammation signs. This study was performed to determine any histopathological alteration in the rabbits’ eyes after the optimum formula and the AGM solution installation with saline solution (as negative control). An aliquot of 100 μl of the AGM-loaded optimum formula was installed to the right eye of the rabbits of groups A and B (into the lower conjunctival cul-de-sac) three times daily for seven days. The AGM solution was installed in the left eyes of the tested rabbits in group A, but for group B, saline solution was applied to the left eye for comparison purposes. At the end of the study period, the rabbits were anaesthetised and sacrificed by decapitation. Then, the eyeballs were extracted, washed with PBS (pH 7.4), and preserved in 10%v/v formalin saline solution until monitored (Abdellatif et al.2022). Then, the tissues were washed with distilled water then subjected to serial dilutions by alcohol for dehydration purposes. Then, samples were added to xylene and fixed in melted paraffin blocks at 56 °C for 24 h. Then, paraffin beeswax tissue blocks with a 4 μm thickness were prepared by a sledge microtome (Leica Microsystems SM2400, Cambridge, UK). After that, the prepared sections were placed on glass slides and stained with haematoxylin and eosin stain. Finally, these stained sections were examined under a light microscope (Leica Imaging Systems Ltd, Cambridge, UK) (Baydoun et al.2004).
Related Knowledge Centers
- Benzene
- Methyl Group
- Organic Chemistry
- Organic Compound
- Pyrolysis
- Preferred Iupac Name
- Hydrogen
- Ethylbenzene
- Empirical Formula
- Catalytic Reforming