Nitrobenzene is an oily yellow liquid with an almond-like odor. It may be pale yellow-brown in appearance. It dissolves only slightly in water, but very easily in some other chemicals.
Nitrobenzene is produced in large quantities for industrial use. Approximately 98% of the nitrobenzene produced in the United States is used to manufacture a chemical known as aniline. Nitrobenzene is also used to produce lubricating oils such as those used in motors and machinery. A very small amount of nitrobenzene is used in the manufacture of dyes, drugs, pesticides, and synthetic rubber.
Exposure to nitrobenzene
Small amounts of nitrobenzene are released to the air and to bodies of water by the industries that use this chemical. However, it is broken down to other chemicals within a few days after it is released. Air and water in most areas contain no nitrobenzene or such low amounts that they cannot be measured.
Nitrobenzene pathways in the body
Because nitrobenzene is not usually found at hazardous waste sites, it is unlikely that you will be exposed to nitrobenzene if you live near one of these sites. However, you may be exposed if you live near one of the seven waste sites where it has been found or near a manufacturing or processing plant, such as those involved in petroleum refining and chemical manufacturing. Persons in these areas may be exposed to nitrobenzene in the air they breathe. However, even in these cases, the levels of nitrobenzene have been found to be extremely low, usually less than 1 ppb (one part nitrobenzene per billion parts of air). Levels of nitrobenzene in the air of residential areas are even lower. Nitrobenzene is almost never found in drinking water. There is no information available on the levels of nitrobenzene in food.
The most common way that humans are exposed to this compound is by occupational exposure. If you work in a plant or factory that produces nitrobenzene or uses nitrobenzene to make other products such as dyes, drugs, pesticides or synthetic rubber, you may be exposed to nitrobenzene in the air that you breathe or through your skin.
Health effects of nitrobenzene
Nitrobenzene can cause a wide variety of harmful health effects to exposed persons. Direct contact of small amounts of nitrobenzene with the skin or eyes may cause mild irritation. Repeated exposures to a high concentration of nitrobenzene can result in a blood condition called methemoglobinemia. This condition affects the ability of the blood to carry oxygen.
Following such an exposure, the skin may turn a bluish color. This may be accompanied by nausea, vomiting and shortness of breath. Effects such as headache, irritability, dizziness, weakness, and drowsiness may also occur. If the exposure level is extremely high, nitrobenzene can cause coma and possibly death unless prompt medical treatment is received. Consuming alcoholic beverages during nitrobenzene exposure may increase the harmful effects of nitrobenzene. In studies with laboratory animals, a single dose of nitrobenzene fed to male rats resulted in damage to the testicles and decreased levels of sperm. This suggests that decreased fertility may be a concern in humans. There is very little information available about the effects of long-term exposure of humans or animals to nitrobenzene, and it is not known whether exposure to nitrobenzene can cause cancer.
Levels of exposure
Nitrobenzene can be smelled in water when it is present at 0.11 mg/L (milligrams of nitrobenzene per liter of water) or in air at 0.018 ppm (0.018 parts of nitrobenzene per million parts of air). It has an odor characteristic of bitter almonds or shoe polish.
It is not known what nitrobenzene levels result in harmful health effects in people. Damage to the kidneys and increased methemoglobinemia in rats is seen at 5 ppm. Damage to the spleen, liver, and testes of rats has been noted at levels of 50 ppm nitrobenzene in air.
Medical test to determine exposure
Nitrobenzene reacts with red blood cells in the body to produce methemoglobin. If you have recently been exposed to nitrobenzene, the levels of methemoglobin in your blood will be elevated. This level can be measured. However, many toxic chemicals produce methemoglobin, and this method does not give specific information about nitrobenzene exposure.
In cases of long-term exposure to nitrobenzene, the presence of its breakdown products, p-nitrophenol and p-aminophenol, in the urine is an indication of nitrobenzene exposure. These tests require special equipment and cannot be routinely done in a doctor's office. The results of these tests cannnot be used ot determine the level of nitrobenzene esposure or if harmful health effects can be expected to occur.
Disclaimer: This article is taken wholly from, or contains information that was originally published by, the Agency for Toxic Substances and Disease Registry. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the Agency for Toxic Substances and Disease Registry should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.