Health effects of acrylonitrile
Contents
Introduction
Acrylonitrile is a colorless, liquid, human-made chemical with a sharp, onion or garlic-like odor. Acrylonitrile is used mostly to make plastics, acrylic fibers, and synthetic rubber. Since acrylonitrile evaporates quickly, it is most likely to be found in the air (Health effects of acrylonitrile) around chemical plants where it is made. Acrylonitrile breaks down quickly in the air. It has been found in small amounts in the water and soil near manufacturing plants and hazardous waste sites. In water, acrylonitrile usually breaks down in about 1 to 2 weeks, although this can vary depending on conditions. For example, high concentrations of acrylonitrile (such as might occur after a spill) tend to be broken down more slowly. In one case, measurable amounts of acrylonitrile were found in nearby wells 1 year after a spill.
Exposure to acrylonitrile
Unless you live near a factory where acrylonitrile is made or near a hazardous waste site that contains acrylonitrile, you are unlikely to be exposed to acrylonitrile in the air you breathe or the water you drink. Concentrations of acrylonitrile in average air samples are too low to be measured, and most water samples also have no measurable acrylonitrile. Measurable amounts of acrylonitrile are found primarily near factories and hazardous waste sites. Concentrations in the air near a factory producing or using acrylonitrile average less than 1 part per billion (ppb). Extremely small amounts of acrylonitrile may be found in water near some factories that make or use it, but acrylonitrile rapidly breaks down and disappears from water. Plastic food containers that are made from acrylonitrile are regulated by the U.S. Food and Drug Administration (FDA) such that only 0.17 parts per billion (ppb) can enter food; therefore, acrylonitrile intake from food packaging would be extremely low. Because acrylonitrile has been found in water and soil in some hazardous waste sites that contain this chemical, residents living very close to waste sites might possibly be exposed to acrylonitrile by breathing the air or drinking contaminated groundwater.
Pathways of acrylonitrile in the body
Acrylonitrile can enter your body if you breathe its vapors or eat or drink acrylonitrile-contaminated food or water. Acrylonitrile can pass through your skin, but how much gets through is not known. Inside the body, acrylonitrile is broken down into other chemicals, including cyanide. Most of these breakdown products are removed from the body in the urine. Overall, most acrylonitrile is removed from the body within 24 hours, but approximately 25% of what is taken in becomes attached to materials inside cells of the body.
Health effects of acrylonitrile
The effects of acrylonitrile on your health depend on how much you take into your body and whether you are exposed for a short or long period of time. If the levels of acrylonitrile are high enough, or if the exposure is for a long enough period of time, acrylonitrile can cause death. Small children are more likely to be affected than adults. In several cases, children died following exposures that adults found only mildly irritating. It should be noted that specific levels of acrylonitrile causing death were not reported.
Exposure to large amounts of acrylonitrile for a short period of time, as might occur in the case of an industrial accident, results mainly in effects on the nervous system. Symptoms can include headache and nausea. At higher concentrations of acrylonitrile there may be temporary damage to red blood cells and the liver. These symptoms disappear when the exposure is stopped.
Direct contact of your skin with acrylonitrile will damage the skin so that it may blister and peel. Exposure of the skin to high concentrations of acrylonitrile in the air may irritate the skin and cause it to turn red. The redness may last for several days.
You should know that one way to learn whether a chemical will harm people is to determine how the body absorbs, uses, and releases the chemical. For some chemicals, animal testing may be necessary. Animal testing may also help identify such health effects as cancer or birth defects. Without laboratory animals, scientists would lose a basic method for getting information needed to make wise decisions that protect public health. Scientists have the responsibility to treat research animals with care and compassion. Scientists must comply with strict animal care guidelines because laws today protect the welfare of research animals.
Additionally, there are vigorous national and international efforts to develop alternatives to animal testing. The efforts focus on both in vitro and in silico approaches and methods. For example, the National Toxicology Program (NTP) at the National Institute of Environmental Health Sciences (NIEHS) created the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM) in 1998. The role of NICEATM is to serve the needs of high quality, credible science by facilitating development and validation—and regulatory and public acceptance—of innovative, revised test methods that reduce, refine, and replace the use of animals in testing while strengthening protection of human health, animal health and welfare, and the environment. In Europe, similar efforts at developing alternatives to animal-based testing are taking place under the aegis of the European Centre for the Validation of Alternative Methods (ECVAM).
The U.S. Department of Health and Human Services has determined that acrylonitrile may reasonably be anticipated to be a carcinogen. Long-term exposure to acrylonitrile in air or water may increase your chances of getting cancer. Humans who are repeatedly exposed to acrylonitrile in the workplace for many years may have a higher-than-average chance of developing lung cancer, although this is not clearly established. In animals, exposure to acrylonitrile in the air or in drinking water has been found to increase the number of tumors occurring in the brain, salivary glands, and intestines.
Birth defects have been seen in animals exposed to high concentrations of acrylonitrile in the air or drinking water. Reproductive effects have been seen in animals given acrylonitrile in drinking water for three generations. However, no birth defects or effects on reproduction have been reported in humans.
Exposure levels
In humans, breathing acrylonitrile at a concentration of 16 parts of acrylonitrile per million parts of air (ppm) causes headaches, nausea, and disorientation. This concentration is close to that at which acrylonitrile can be smelled in air (about 21 ppm). Breathing acrylonitrile in air for long periods of time and at high concentrations can cause death. The actual concentrations of acrylonitrile and breathing times which cause death have not been measured. There is no information on human health effects from eating or drinking acrylonitrile. Acrylonitrile can be smelled at a concentration of 19 ppm when dissolved in water.
In animals, drinking water that contains 142 ppm of acrylonitrile has caused nervous system disorders leading to death. Birth defects and effects on reproduction have occurred in animals that breathed acrylonitrile in air at levels of 80 ppm or drank it in water at 180 ppm.
Medical tests for exposure to acrylonitrile
There is a test that can detect acrylonitrile in blood. In addition, the major breakdown products of acrylonitrile by the body (termed metabolites) can be measured in urine. Some breakdown products that can be measured are specific to acrylonitrile. However, one breakdown product of the body (cyanide) that is commonly measured is not specific to acrylonitrile exposure, and the results can be affected by cigarette smoking. Because special equipment is needed, these tests cannot be performed routinely in your doctor's office. There is not enough information at present to use the results of such tests to predict the nature or severity of any health effects that may result from exposure to acrylonitrile.
Further Reading
- The Agency for Toxic Substances and Disease Registry
- Interagency Coordinating Committee on the Validation of Alternative Methods
- European Centre for the Validation of Alternative Methods
- Institute for Laboratory Animal Research
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