After five years of study, EPA has made a final decision not to regulate dioxins in land-applied sewage sludge. On October 17, the agency concluded that dioxins from this source do not pose a significant risk to human health or the environment.
The most highly exposed people, theoretically, are those people who apply sewage sludge as a fertilizer to their crops and animal feed and then consume their own crops and meat products over their entire lifetimes. EPA's analysis shows that even for this theoretical population, only 0.003 new cases of cancer could be expected each year or only 0.22 new cases of cancer over a span of 70 years.
The risk to people in the general population of new cancer cases resulting from sewage sludge containing dioxin is even smaller due to lower exposures to dioxin in land-applied sewage sludge than the highly exposed farm family which EPA modeled.
EPA's 2001 Dioxins Update to the National Sewage Sludge Survey indicates that dioxins levels in treated sewage sludge have declined since the last EPA survey in 1988. This downward trend is expected to continue as regulatory controls are placed on additional sources of dioxins in the environment, particularly on some combustion practices.
Dioxins are a group of highly toxic persistent compounds which are a byproduct of certain combustion and chemical manufacturing processes. Sewage sludge is the byproduct of the treatment processes which purifies wastewater before it is released into local waterways.