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Dioxin describes a small family of dangerous, toxic chemicals found sparsely in nature, but commonly manufactured as by-products of other materials. An increase in synthesized pesticides in the late 1960s first brought attention to the possible poisonous effects of dioxin on factory workers. By the time researchers linked dioxin to cancer, these chemicals had leaked out and become part of widespread environmental pollution.
Chemically, a dioxin molecule has chlorine atoms attached, at specific points, to a basic structure of oxygen and carbon atoms. One could say that the chlorine binds at strategically placed intervals, since some of their locations result in a less toxic chemical than others. Still, all molecules arranged in that manner, otherwise known as trichlorophenols, are referred to as dioxin. In its raw form, dioxin looks like whitish crystals resembling granulated sugar, but unlike sugar it does not dissolve in water. It's fat soluble, so it can dissolve and be stored in human fat deposits.
Low amounts of dioxin are naturally present in high temperature combustion, such as in intense forest fires. However, the amount of dioxin in the environment skyrocketed when chemists embarked upon the next era of pesticide manufacture in the 1960s. Strong defoliants, such as Agent Orange, created dioxin as an unintended byproduct. At first, only the factory workers exposed to high levels of dioxin exhibited increased rates of cancers.
Soon government environmental and health agencies were interested in the dangers to the different populations and their levels of exposure. Initial studies focused on populations at high-risk employment, such as garbage incinerators and herbicide manufacturers, found a well-established cancer risk, higher incidence of heart disease, developmental complications, diabetes, compromised immune systems, and possibly disrupted reproductive functions. However, this small group hinted at possible problems in the wider population who have been shown to have low levels of dioxin in fat deposits, usually from eating polluted food.
As far as biologists know, dioxin damages normal physiological functions by mimicking the way hormones work. This means dioxin penetrates cell walls and changes DNA so that the DNA sends unpredictable messages. These messages result in altered production of enzymes and proteins, rather than their proper regulation by hormones. Scientists do not yet fully understand the relationship between altered DNA and diseases such as cancer, but they are concerned about the toxic effects of dioxin in food supplies, and support continued research.