The EPA requires that dioxin-bearing wastes be destroyed or reduced by:

The requirement for the destruction or reduction of dioxin-bearing wastes set by the EPA at 99.9999 percent reflects the extreme toxicity and persistence of dioxins in the environment. Dioxins are classified as some of the most harmful environmental pollutants, largely due to their ability to accumulate in the food chain and their long half-lives, which can result in prolonged exposure risks to both human health and ecosystems.

Setting such a high threshold for destruction ensures that almost all of the dioxin is eliminated, minimizing any potential harmful effects that could result from even trace amounts. This rigorous standard is in line with the EPA's broader mission to protect human health and the environment, particularly in cases involving highly hazardous substances like dioxins.

Other choices represent significantly lower thresholds for destruction, which would not be sufficient given the attributes of dioxins. A standard of 99.99 percent, for instance, could still allow for dangerous levels of dioxin to remain. Therefore, the requirement of 99.9999 percent is essential to ensure comprehensive safety and environmental protection.