Of the hundreds of known dioxins, about 30 are known to be toxic, with significant health impacts on humans. They accumulate in animal fats which may be part of the food supply. The chemical name for dioxin is 2,3,7,8- tetrachlorodibenzo para dioxin TCDD.
The name "dioxins" is often used for the family of structurally and chemically related chlorinated dibenzo para dioxins CDDs, including polychlorinated dibenzo para dioxins, or PCDDs and polychlorinated dibenzofurans PCDFs.
Dioxins are persistent organic pollutants POPs , meaning they do not easily break down in the environment. CDDs are not intentionally manufactured by industry, except in small amounts for research purposes. CDD emissions associated with incineration and combustion activities are the primary environmental source. The CDD family includes 75 chemicals divided into eight groups based on the number of chlorine atoms in the compound, as shown in the table.
Thus we focus on 2,3,7,8-TCDD here. In the pure form, CDDs are colorless solids or crystals. CDDs enter the environment as mixtures containing a variety of individual components and impurities. Various formulations of 2,4,5-T have been used extensively for weed control on crops and range lands, and along roadways throughout the world.
Dioxins accrue in fat tissue and bioaccumulate in the food chain. Being highly lipophilic, dioxins dissolve in fat, where they can be stored for long periods. To be excreted from the body, they must first be metabolized in the liver to become water soluble. However, dioxins are metabolized slowly and therefore tend to accumulate in fat and in the liver.
The speed of elimination of dioxins can vary with dose, quantity of body fat, age and sex. The process of elimination of dioxins and PCBs is similar in animals and humans, but it is faster in most other mammals.
Although dioxin 2,3,7,8-TCDD was first recognized as toxic for its effects on chemical industry workers in the late 19th century, it was not declared a probable human carcinogen by the US Environmental Protection Agency EPA until Dioxins, especially TCDD, are considered highly toxic; they are carcinogenic and can damage the immune, reproductive , and developmental systems, especially by interfering with hormone activity.
Data from animal models suggest TCDD is linked to endometriosis , developmental and neurobehavioral effects , developmental reproductive effects , and immunotoxic effects. Acute dioxin exposure TCDD can cause chloracne , redness and pain.
The developing fetus and newborn, with rapidly developing organ systems, may also be most vulnerable to certain effects of exposure. Some individuals or groups of individuals may be exposed to higher levels of dioxins:. Dioxins can be absorbed into the body by inhalation of dust, through the skin and by ingestion. Diet is the primary source for human exposure to dioxins, primarily through animal fats in meat and dairy products.
Human breast milk is unfortunately a contaminated food source, and breastfed infants may have a daily intake of dioxins per pound of body weight 10 to times greater than for adults. CDDs also have been detected at low concentrations in cigarette smoke, home heating systems, and exhaust from vehicles running on gasoline either leaded or unleaded or diesel fuel. Who Studies Immunotoxicology? What is Gene Expression? Who Studies Developmental Toxicology? What Is Dioxin? TCDD, 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin What are the major sources of dioxin?
Dioxin is released into the environment and builds up in sediment. Fish build up dioxin in their fat. How would I most likely be exposed to dioxin? Eating fish from contaminated waters can lead to dioxin exposure in people. EPA granted the petitioners' requests for reconsideration and provided the public with an opportunity to comment on a proposed rule to amend the emissions standards.
Congress added Section to the CAA in specifically to address emissions from solid waste combustion. NSPS are direct federal regulations that apply to new sources. EG do not directly regulate solid waste combustion units.
Rather, EG establish requirements for state plans to implement the guidelines. Once approved, the state plans become federally enforceable. For further information see the CAA guidelines and standards for waste management.
Section includes a list of the waste incineration rules. Under TSCA section 8 e , any person who manufactures including imports , processes, or distributes in commerce a chemical substance including, generally, dioxin or mixture and who obtains information which reasonably supports the conclusion that such substance or mixture presents a substantial risk of injury to health or the environment to immediately inform EPA, except where EPA has been adequately informed of such information.
Section of the Emergency Planning and Community Right-to-Know Act of EPCRA requires certain facilities manufacturing, processing or otherwise using listed chemicals to report their environmental releases of such chemicals annually. The list of reportable chemicals, known as the EPCRA section list and also referred to as the Toxics Release Inventory, or TRI list, was originally identified in the statute and was comprised of more than individual chemicals and 20 chemical categories.
Skip to main content. Related Topics: Dioxin. Contact Us. Dioxin Key Facts Dioxins are called persistent organic pollutants POPs , meaning they take a long time to break down once they are in the environment. Dioxins are found throughout the world in the environment , and they accumulate in food chain s , concentrating mainly in the fatty tissue of animals. What is Dioxin? Applicable Laws Research Timeline. Figure 1: Dioxin chemical structures.
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