Health effects of 2,4- and 2,6-dinitrotoluene

Introduction

2,4-DNT and 2,6-DNT are pale yellow solids with a slight odor and are two of the six forms of the chemical called dinitrotoluene (DNT). The other four forms (2,3-DNT, 2,5-DNT, 3,4-DNT, and 3,5-DNT) only make up about 5 percent of the technical grade DNT. DNT is not a natural substance but rather is usually made by reacting toluene (a solvent) with mixed nitric and sulfuric acids, which are strong acids. DNT is used to produce flexible polyurethane foams used in the bedding and furniture industry. DNT is also used to produce ammunition and explosives and to make dyes. It is also used in the air bags of automobiles. It has been found in the soil, surface water, and groundwater of at least 122 hazardous waste sites that contain buried ammunition wastes and wastes from manufacturing facilities that release DNT. DNT does not usually evaporate and is found in the air only in manufacturing plants. DNT also does not usually remain in the environment for a long time because it is broken down by sunlight and bacteria into substances such as carbon dioxide, water, and nitric acid.

Pathways for 2,4- and 2,6-dinitrotoluene in the environment

DNT can be found in air, surface water, groundwater, and soil. Releases to the air are usually in the form of dusts or aerosols from manufacturing plants. Evaporation from water containing DNT is not a likely means of release to the air. DNT is thought to break down in air by a variety of chemical reactions that take place upon exposure to sunlight.

In water, DNT can be broken down by sunlight. Under conditions without oxygen or without light, DNT may be broken down by biological degradation, whereby microbes utilize the chemical as a source of energy and convert it into chemicals such as carbon dioxide and water. DNT in surface water from rivers and streams and groundwater from wells can result from releases of waste water from trinitrotoluene (TNT) manufacturing facilities and from buried munition wastes.

No information was located regarding the changing of DNT to other chemical substances in soil. DNT is unlikely to build up in animal tissues after animals are exposed by eating impacted soil, water, or vegetation, or by inhaling contaminated air. However, since DNT is quite soluble in water, it can be transferred to plants via root uptake from soil or irrigation with contaminated water, although no direct measurements have been found. It is, however, expected to accumulate readily in plant materials, although no direct measurements have been found.

Exposure to 2,4- and 2,6-dinitrotoluene

Members of the general population are likely to be exposed only if they are near a DNT contaminated waste site or manufacturing facilities that release DNT.

2,4- or 2,6-DNT may enter the environment from waste waters that industries discharge into rivers and streams or from the improper disposal of wastes. However, regular testing of water in the United States shows that 2,4- and 2,6-DNT were found in less than 2% of the water samples. Testing of hazardous waste sites shows that 2,4- and 2,6-DNT are present at less than 8.5% of these sites. Available information indicates that DNT does not appear to be widespread in the environment.

Pathways for 2,4- and 2,6-dinitrotoluene in the body

When industrial workers are exposed to 2,4- or 2,6-dinitrotoluene, the major ways that these chemicals enter their bodies are by breathing or absorbing small amounts of the chemical through the skin. Some ingestion may also occur as the result of eating or smoking without prior handwashing.

After individuals breathe air, drink water, or eat food contaminated with 2,4- or 2,6-DNT, these chemicals are changed into different substances by the liver and in the intestines. After this, most of these chemicals leave the body within 24 hours in the urine, with a small amount in the feces. This information comes from animal experiments done in laboratories and from studies of industrial workers.

Health effects of 2,4- and 2,6-dinitrotoluene

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).

When industrial workers are exposed to 2,4- or 2,6-dinitrotoluene, the major ways that these chemicals enter their bodies are by breathing or absorbing small amounts of the chemical through the skin. Some ingestion may also occur as the result of eating or smoking without prior handwashing.

After individuals breathe air, drink water, or eat food contaminated with 2,4- or 2,6-DNT, these chemicals are changed into different substances by the liver and in the intestines. After this, most of these chemicals leave the body within 24 hours in the urine, with a small amount in the feces. This information comes from animal experiments done in laboratories and from studies of industrial workers.

Health effects in children

This section discusses potential health effects from exposures during the period from conception to maturity at 18 years of age in humans. Potential effects on children resulting from exposures of the parents are also considered.

2,4- and 2,6-DNT are not widespread throughout the environment. If you do not live near a plant or a waste site that contains DNT, it is unlikely that your children would be exposed to DNT. DNT is normally associated with industrial or military production plants or munitions storage sites. DNT is water soluble, so if contamination has occurred it will usually be carried in water. Children are at risk for exposure if DNT has leached into a community's drinking water supply from a nearby hazardous site since they drink more fluid in proportion to their body weight than adults. Children playing in DNT-contaminated surface water might be more exposed than adults, both because of this behavior and because of their larger skin area in proportion to their body weight.

Since DNT exposure is usually related to adult workers, health effects on children have not been studied. It is not known if DNT affects children differently than adults, or what long term effects might appear in adults exposed as children.

No studies have investigated effects of DNT on the developmental process in humans, and few studies have focused on animals. No studies have been done to see if DNT or its toxic breakdown products cross the placenta, or get into breast milk.

Reducing risk of exposure to 2,4- and 2,6-dinitrotoluene

If your doctor finds that you have been exposed to significant amounts of 2,4-DNT or 2,6-DNT, ask if children may also be exposed. When necessary your doctor may need to ask your State Department of Public Health to investigate.

If you live near a site that could be contaminated with DNT you should discourage your children from putting foreign objects, groundwater, and dirt in their mouths since DNT is quite water soluble. Make sure they wash their hands frequently and before eating. Discourage your children both from putting their hands in their mouths and from other hand-to-mouth activities

Medical tests for exposure to 2,4- and 2,6-dinitrotoluene

Both 2,4- and 2,6-DNT and the chemicals they are changed into by the body can be measured in the blood and urine of exposed individuals (if urine is collected within 24 hours). The tests cannot show how much 2,4- or 2,6-DNT an individual has been exposed to. These tests are not usually available in doctors' offices but can be performed by special laboratories.

Further Reading



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.

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Citation

(2008). Health effects of 2,4- and 2,6-dinitrotoluene. Retrieved from http://www.eoearth.org/view/article/51cbedf77896bb431f695188

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