NCPA - National Center for Policy Analysis

Sewage Sludge

January 9, 2004

There is negligible harm in using sludge from wastewater treatment plants as a farm fertilizer, according to a five-year study by the Environmental Protection Agency. Environmental groups have called for the government to regulate the use of treated sewage sludge, claiming that it contains enough of the chemical dioxin to increase the risk of cancer. However, the EPA's study concluded that:

  • In a worst-case scenario, where a farm family applies sewage sludge to their crops for a lifetime and then consumes a substantial amount of their own crops, the risk of a family member developing a new case of cancer is only 0.003 per year.
  • The EPA notes that dioxin levels in sludge have been substantially reduced since its last report, in 1988, and that dioxin levels in the environment have been reduced 90 percent.

Moreover, since farm families are not representative of most consumers, the risk to the general population is even lower. Geoffrey Grubbs, EPA's director of water science and technology programs, quotes the risk of cancer from dioxin as being, "small, substantially smaller than other chemicals we regulate." Additionally, the EPA found no significant effects on wildlife from the use of sludge, and for now does not plan to regulate the practice.

Source: James M. Taylor, "EPA: No Harm in Using Sewage Sludge as Fertilizer," Environment and Climate News, December 2003, Heartland Institute.

For EPA sludge study


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