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DIOXINS found in the blood of Mossville residents are among the most toxic chemicals known. One form of dioxin was the main toxic ingredient of the defoliant Agent Orange used during the Vietnam War. Dioxins are ubiquitous in the environment in tiny amounts, and traces are present in everyone's body. In higher amounts, they have been linked to cancer and other health effects. In recent years, dioxin levels have fallen thanks to environmental controls. Here's a look at how dioxins get into the body.
1. TAKING TO THE AIR
Dioxins are created in a number of ways. The most common is combustion. When a plant burns chemical waste containing chlorine, or landfills incinerate municipal waste, dioxins are formed and released into the air. They eventually imbed themselves in soil and make their way into the food chain, where they can end up in people's bodies.
2. ENTERING A HUMAN CELL
The dioxin compound penetrates the cell membrane and attaches itself to a protein called a receptor. Receptors are part of a signalling system that relays chemical messages from the rest of the body to the cell. Dioxin molecules interfere with that system, either by sending a false signal or blocking the right signal. The dioxin molecule and receptor join with another protein, travel into the nucleus and head for the chromozomes that govern reproduction.
3. TARGET: DNA
Wrapped tightly within each chromozome is the complex, yet delicate DNA structure that contains the body's complete genetic code.
4. ATTACHING TO DNA
The linked receptor-dioxin molecules attach themselves to sections of DNA as the cell divides. They mistakenly switch on genes that make specific proteins.
5. ALTERING THE CELLS
As the unwanted proteins are made in cells throughout the body, scientists believe, they can help trigger the out-of-control cell division of cancer and many other health effects.
Fish: Scientists believe Mossville residents may have been exposed by eating fish from the polluted Calcasieu estuary.
Cattle, pigs, chickens, eggs: Food from a common source, such as locally-produced eggs or meat, or even a source farther away, could also be a source of exposure.
Air: It's also possible to be exposed by breathing dioxin-laced fumes from combustion, though this is less likely.
Pregnancy and breast-feeding: A pregnant women with dioxins in her bloodstream can transfer the chemicals to her unborn child through the placenta. The production of breast milk, which is high in fat, leaches dioxins from a mother's body and can transfer them to a breast-feeding baby.