S E W A G E S L U D G E (via EnviroNet, 4/29/89) In recent weeks, there has been some discussion here on toxic contamination in municipal sewage sludge and the inadvisability of using this seemingly innocuous material in the garden, on the lawn, or in agriculture. A number of U.S. cities distribute their sludge, in either dry form or as a slurry, to farmers for use on crops and to industries and governments for "land spreading" on forests. Some distribute it directly to the public. Milwaukee's, for example, is sold all over the U.S. (and even in Canada, I believe) as "Milorganite." Despite some of the highest contaminant levels in the country, Milorganite was until a few years ago actively promoted as an "organic fertilizer" for general use. It is still prominently labelled "organic fertilizer," but the bags now carry a small-print warning that the product should be used only on flower gardens, lawns, and areas where no food is grown. This latter label was added several years ago following some highly publicized speculation that the product was connected to a number of mysterious outbreaks of ALS (better known as Lou Gehrig's Disease), which destroys the human nervous system. Milwaukee's sludge may be more heavily contaminated than the sludge produced elsewhere, but wherever industry is allowed to dump toxic metals and synthetic chemicals down the drain, the sludge produced by the municipal sewage system will be contaminated. Volatile contaminants tend to evaporate during the conventional sewage treatment process; but significant quantities of volatiles -- and virtually all of the metals and other contaminants -- remain in the sludge. Years ago, Rodale and other advocates of organic agriculture urged the use of sewage sludge as a soil amendment. If you have information about the use of municipal sewage sludge by "organic" gardeners and farmers, or about the policy of state organic certification programs regarding such use, please let me know. The information that follows, contributed by Greenpeace toxics campaigner Joe Thornton, was derived from U.S. EPA's1986 "Domestic Sewage Study." Jeff Howard -------------------------------------------------------- Sludge from our nation's sewage treatment plants contain 9.07 million pounds per year of heavy metals, 9.7 million pounds per year of volatile organics (solvents like benzene, chloroform, etc.), 6.6 million pounds per year of base neutrals (long-chain hydrocarbons like benzo-a-pyrene, chlorinated benzenes and butadienes, and phthalates), 3.3 million pounds per year of acid-extractables (phenols, chlorophenols, and nitrophenols), and between 10,000 and 25,000 pounds per year of PCBs and pesticides. A 1984 US EPA Study on sludge disposal estimated that of all the nation's sewage sludge, 24 percent is land-applied, plus another 18 percent is distributed/marketed for further land use. 15 percent is landfilled, 27 percent is incinerated, and 4 percent is disposed at sea. "Other," whatever that means, accounts for the last 12 percent. Extrapolations are yours to make. I don't know much about fate of these pollutants in terrestrial ecosystems, except that cadmium is rapidly taken up by plants from soil, and that the phthalates and most of the chlorinated compounds are bioaccumulative in aquatic ecosystems (a fact which is relevant if the pollutants leach or runoff from the land into surface waters). [Joe Thornton]