Xylene (dimethyl benzene) is a mixture of the three isomers plus ethylbenzene (6-15%) and occasionally toluene, trimethyl benzene and other trace components. It is widely used as a solvent and thinner for paints and varnishes, often in combination with other organic compounds and as a solvent in glues, printing inks, and fat solvent in microscopy.

Xylene is very similar to toluene in its toxicological effects in that it is primarily a skin irritant, and like other organic solvents it can produce defatting dermatitis after prolonged exposure. Xylene acts as a narcotic if inhaled in high concentrations.

Over 95% of xylene metabolism involves a pathway of oxidation to methylbenzyl alcohol and subsequent reduction, via alcohol dehydrogenase by aldehyde dehydrogenase, to methyl benzaldehyde and methyl benzoic (or toluic) acid respectively.p>

The major risk from xylene high level exposures is progressive inhibition of nervous system function, culminating in coma, respiratory depression and ultimately death from brain damage due to lack of oxygen.