ATSDR Evaluation of Health Effects of Chemicals. V. Xylenes: Health Effects, Toxicokinetics, Human Exposure, and Environmental Fate

Abstract

Xylenes, or dimethylbenzenes, are among the highest-volume chemicals in production. Common uses are for gasoline blending, as a solvent or component in a wide variety of products from paints to printing ink, and in the production of phthalates and polyester. They are often encountered as a mixture of the three dimethyl isomers, together with ethylbenzene. As part of its mandate, the Agency for Toxic Substances and Disease Registry (ATSDR) prepares toxicological profiles on hazardous chemicals found at Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List (NPL) sites that are of greatest concern for public health purposes. These profiles comprehensively summarize toxicological and environmental information. This article constitutes the release of the bulk of this profile (ATSDR, 1995) into the mainstream scientific literature. An extensive listing of known human and animal health effects, organized by route, duration, and end point, is presented. Toxicological information on toxicokinetics, biomarkers, interactions, sensitive subpopulations, reducing toxicity after exposure, and relevance to public health is also included. Environmental information encompasses physical properties, production and use, environmental fate, levels seen in the environment, analytical methods, and a listing of regulations. ATSDR, as mandated by CERCLA (or Superfund), prepares these profiles to inform and assist the public.

Dearomatisation of o‐Xylene by P450BM3 (CYP102A1)

“…The organic layer was washed twice with an equal volume of water, once with 10 m KOH and once with 20 m KOH to remove the phenolic products, and three times more with water. After drying over anhydrous MgSO 4 and distillation at 50 8C, the majority of the solvent was gently evaporated prior to NMR spectroscopy. Silica chromatography was used as a final purification step prior to UV/Vis spectroscopy, the mobile phase being hexane/ethyl acetate (8:2).…”

“…The commonest reaction type is the conversion of an unreactive carbonÀhydrogen bond to the corresponding alcohol, but epoxidation of olefinic linkages, dehydrogenation and dealkylation are also known. [1,2] CYP enzymes play roles in numerous metabolic pathways, both catabolic and anabolic, notably those relating to the biosynthesis of hormones and antibiotics [2,3] and the breakdown of xenobiotics, such as the benzene, toluene, ethylbenzene and xylene [4] (BTEX) family of contaminants. [5] P450 BM3 (CYP102A1), a sub-terminal fatty-acid hydroxylase from Bacillus megaterium, has been widely researched, partly because it is catalytically self-sufficient and water-soluble.…”

Inactivation of Mycobacterium bovis in cattle slurry by five volatile chemicals

“…Plommet (1972) used xylene at a concentration of 0·1% in slurry for inactivation of Brucella abortus . Toxic effects in humans due to exposure to xylene include eye and respiratory tract irritation, central nervous system changes and damage to the liver and kidneys (Fay et al . 1998).…”

The role of toxicokinetics in xylene-induced ototoxicity in the rat and guinea pig

“…The toxicology of xylenes has been described in several reviews (Carpenter et al, 1975;ECETOC, 1986;Low et al, 1989;Fay et al, 1998;US EPA, 2003) and, in general, the studies have indicated little toxicity associated with these solvents. However, xylenes belong to the aromatic solvents, some of which, like toluene, styrene or ethylbenzene, show a characteristic toxicity on the auditory system of the rat characterized by an irreversible hearing loss, as measured by behavioural or electrophysiological methods, associated with damage to hair cells in the cochlea of the exposed animals (Pryor et al, , 1984(Pryor et al, , 1987Rebert et al, 1983;Sullivan et al, 1988;Johnson and Canlon, 1994;Yano et al, 1992;Campo et al, 1997;Cappaert et al, 1999Cappaert et al, , 2000Cappaert et al, , 2001Cappaert et al, , 2002.…”