Xylene (pronounced zi len or zy’ leen) is either a liquid or a colorless
, sweet-smelling gas. There are 3 isomers of X (ortho, meta, para), with boiling points 144 C, 139 C and 138 C, so they are all liquids at room temperature. But of course, there are always vapors above the liquid; the vapors have a sweet smell. You can smell Xylene in the air at 80 parts of Xylene per billion parts of air (ppb). That means you can easily smell very very small amounts of it, it's so easy to detect. One ppb means one part of something in a billion parts of something else. To visualize one ppb, imagine one gallon of water compared to enough water to fill 55,555 average-sized swimming pools.
Xylene is mostly a synthetic chemical that is produced from petroleum. It also occurs naturally in petroleum and coal tar and is formed during forest fires. Xylene is used as a solvent in the printing, rubber, and leather industries. It is also used as a cleaning agent, a thinner for paint, and in paints and varnishes. It is found in small amounts in airplane fuel and gasoline and small amounts are found in cigarette smoke.
Chemical Formula: C8H10
Chemical Abstract Number (CAS#): 1330-20-7
Other names: xylol and dimethylbenzene
Xylene is on of the top 30 chemicals produced in the United States in terms of volume. Xylene evaporates quickly from the soil and surface water into the air. In the air, it is broken down over several days by sunlight into less harmful chemicals. Levels of xylene in the outdoor air in urban areas of the United States range from 1 to 88 parts of xylene to per billion parts of air.
You can be exposed to xylene by breathing in vapors from products that contain xylene or by breathing air that is contaminated with xylene. Xylene causes health effects from both short term (acute less than 14 days) and also long term (chronic more than 365 days) exposure. The type and severity of health effects depends upon several factors including the amount of chemical you are exposed to and the length of time you are exposed. Individuals also react differently to different levels of exposure.
Acute exposure (less than 14 days) to high levels of xylene can cause:
Studies of unborn animals who were exposed to high concentrations have shown effects on the growth and development of the fetus. The EPA has not classified xylene as a carcinogen. Neither human nor animal studies of xylene have shown resulting cancer tumors.
At What Levels Should I be Concerned? The Maine Department of Health Services has provided three different guidelines to protect human health based on the length of time of exposure. They are:
- an average of 14,739 parts of xylene per billion parts of air (ppb) for 15 minutes of exposure
- an average of 68 parts of xylene per billion parts of air (ppb) for twenty four hour exposure
- an average of 68 parts of xylene per billion parts of air (ppb) for an average annual exposure
You can reduce your risk from xylene exposure by:
avoiding inhalation of fumes while pumping gas
using gas pumps with vapor control where available
minimizing exposure to vehicle exhaust (e.g. do not idle your car, and use alternative forms of transportation that are less-polluting)
There are various forms of Xylene which includes, meta-xylene, ortho-xylene, and para-xylene (m-, o-, and p- xylene). These different forms are referred to as isomers, meaning that they have the same chemical formula, but a different chemical structure.
Sources of Information:
EPA Integrated Risk Information System, http://www.epa.gov/iris/subst/0270.htm
EPA Health Effects Notebook
Technology Transfer Network Unified Air Toxic Web Site, http://www.epa.gov/ttn/uatw