Dioxin risk in soil and plant tissues after long-term biosolids application

Land application of biosolids (treated municipal sewage sludge) is a common practice because biosolids are a rich source of plant nutrients and organic matter. However, the presence of detectable levels of dioxins in biosolids led to concerns that farmland application may result in accumulation of dioxins in soil and their subsequent translocation through the human food chain because several congeners of dioxins have extremely high bioaccumulation potential. The USEPA evaluated the risk of dioxins in land applied biosolids and concluded that dioxins from this source do not pose a significant risk to human health or the environment. However, there is very little information available on the effect of long-term application of biosolids on accumulation of dioxins in soil and uptake by plants.