Dioxins and heavy metals do not degrade in the environment, since there are no natural processes that decompose them to harmless forms. They are also highly toxic, so much so that even low levels of exposure to these compounds can be poisonous.

Dioxin, the main component that was used in Agent Orange, is so toxic that it endangers life at even low concentrations. "Dioxins have been called the most toxic chemicals known to man," said Tonjes. "The reason for that is an extremely small dose, parts per quadrillion, can cause effects."

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