Worms bear sludge load
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USGS
harmaceuticals and personalglass of what’s in the soil.” clump together and sit atop soils care products (PPCPs) end Kolpin collected worms and soil for months during dry spells if not up in the tons of solid sludge samples from three sites several tilled into the ground. As a result, left behind by wastewater treattimes during a growing season: a the team’s second sample collecment processes. Those so-called soybean field amended with biotion, after the biosolids were apbiosolids are often repackaged and solids (which were not tilled into plied, “may be more representative sold as fertilizers for both industhe soil) from a wastewater treatthan the first,” he says. trial and small-scale agriculture. ment plant, a cornfield treated Tammy Jones-Lepp, a research In a new survey, published in ES&T with swine manure that was tilled chemist at the U.S. EPA Office of (pp 1863–1870), researchers show into the soil, and a soybean field Research and Development Envifor the first time that ronmental Chemthose compounds istry Branch in can turn up in Las Vegas, Nev., earthworms. notes that a couThe findings ilple of the results lustrate the wide seem contradicarray of PPCPs tory with regard to that can be carbioconcentration, ried from treatwith some subment facility to stances appearing field. Biosolids at much highprovide “great value as er levels in the sources of organic carbon soils than in the and nutrient compounds,” worms. She would says coauthor Edward like to have seen Furlong of the U.S. GeoDana Kolpin of USGS collected worms from three agricultural fields, “blank” worms, logical Survey (USGS), but two of which were treated with biosolids or swine manure. raised in a clean “you still have to undertest plot for comstand the trace constituents.” The not amended with biosolids or maparison with the wild worms from proof-of-concept study also demnure. Some PPCPs showed up in the fields. Still, Jones-Lepp says, onstrates that worms are taking up worms at levels several orders of “there definitely is a bioconcentrasome of the compounds into their magnitude higher than in the soil tion factor going on,” and the data tissues and bioconcentrating them samples. raise more questions, for example, there, with unknown effects, says Some substances, including trias to whether the worms break coauthor Dana Kolpin of USGS. closan (an antimicrobial used in down the contaminants in soils in Bioaccumulation of PPCPs by soaps) and the synthetic musks which they live. worms is not entirely a surprise, galaxolide and tonalide, turned up Robert Hale of the Virginia Inaccording to Stockholm Univerat surprisingly high levels. Even stitute of Marine Science observes sity’s Cynthia De Wit, who points the unamended field, which was that earthworms are mobile and to her own work looking at PBDEs to serve as a control site, had high that the most bioaccumulative and other persistent compounds concentrations of perfumes and chemicals likely remain near the in earthworms (Environ. Sci. Techtriclosan in some places. The result surface, raising issues of avoidnol. 2005, 39, 9064–9070). The new partly underscores how hard it can ance behaviors. He also notes that research underscores that worms be to find an uncontaminated site, the fields were treated only once, could serve as monitoring organsays Cliff Rice at the U.S. Departwhereas in practice, biosolids may isms, she says. Because the worms ment of Agriculture. The authors be applied many times to the same seem to concentrate compounds conjecture that the sources of plot. “The field study incorporates that may be present at undetectthese contaminants may be nearby many variables, so simple interpreable levels in the soils, they can be septic systems or surface runoff. tation is difficult.” “a sort of sentinel, or magnifying Rice notes that biosolids tend to —NAOMI LUBICK
1814 ■ Environmental Science & Technology / March 15, 2008
© 2008 American Chemical Society
