Personnel Exposure to Xylene

September 21, 2015 | Healthcare Risk, Quality, & Safety Guidance


Xylene, also called dimethylbenzene, methyl toluene, xylol, or mixed xylenes, is used in hospital laboratories primarily as a solvent to clear tissue specimens of alcohol in order to infuse paraffin and to clear slides of excess stains; it is normally found in the histology, hematology, microbiology, and cytology laboratories (OSHA “Hospital eTool”). Mixed xylene, which includes all three xylene isomers (ortho-, meta-, and para-) plus approximately 6% to 15% ethylbenzene, is a colorless liquid that is insoluble in water and has a sweet odor (ATSDR “Toxic Substances”).

Xylene exposure in the general U.S. population occurs when the chemical is released through industrial emissions (e.g., petroleum refineries, chemical plants) and automobile exhaust, as well as through its use as a solvent, but this chemical is also available in a variety of consumer products, such as gasoline, paint, varnish, and shellac. Xylene evaporates readily (vapor pressure is 7 to 9 torr NIOSH “Occupational”), and as such, is mostly found in the air; however, accidental spills can cause soil and groundwater to become contaminated. Atmospheric xylene levels in the United States range from 1 to 30 parts per billion (ppb), and xylene levels measured indoors range from 1 to 10 ppb. Concentrations may be higher indoors than outdoors due to poor ventilation. (ATSDR “Toxicological Profile”)

This guidance article discusses the potential hazards from xylene, as well as federal regulatory standards, recommended limits, and worker protection.

While the levels of xylene that an average person is exposed to over the course of daily living will likely not be high enough to result in adverse health effects, there may be health hazards for people who work with xylene directly and more frequently, such as hospital laboratory workers. Signs and symptoms of...

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