Scientist collected earthworms from a soybean field fertilized with biosolids.
Earthworms Found to Contain Chemicals from Households and Animal Manure
Released: 2/20/2008 12:00:00 PM
U.S. Department of the Interior, U.S. Geological Survey
Office of Communication
119 National Center
Reston, VA 20192 Edward T. Furlong
Earthworms studied in agricultural fields have been found to contain organic chemicals from household products and
manure, indicating that such substances are entering the food chain.
Manure and biosolids, the solid byproduct of wastewater treatment, were applied to the fields as fertilizer. Earthworms
continuously ingest soils for nourishment and can accumulate the chemicals present in the soil.
The chemicals investigated are considered indicators of human and animal waste sources and include a range of
active ingredients in common household products such as detergents, antibacterial soaps, fragrances, and
pharmaceuticals. Some of the detected chemicals are naturally occurring such as plant and fecal sterols and
fragrances. All of these chemicals tend to be concentrated in the municipal waste distribution and disposal process
and are referred to as anthropogenic waste indicators (AWI).
U.S. Geological Survey Scientists and their colleague from Colorado State University at Pueblo published their new
findings today in Environmental Science and Technology. The results demonstrate that organic chemicals introduced
to the environment via land application of biosolids and manure are transferred to earthworms and enter the food
Scientist collected earthworms from a soybean field fertilized with biosolids. The earthworms were analyzed for 77
different chemicals; 20 chemicals were detected in the earthworms.
Scientists found 28 AWIs in biosolids being applied at a soybean field for the first time and 20 AWIs in earthworms
from the same field. Similar results were found for the field where swine manure was applied. Several compounds were
detected in earthworms collected both from the biosolids- and manure-applied fields, including phenol (disinfectant),
tributylphosphate (antifoaming agent and flame retardant), benzophenone (fixative), trimethoprim (antibiotic), and the
synthetic fragrances galaxolide, and tonalide. Detergent metabolites and the disinfectant triclosan were found in
earthworms from the biosolids-applied field, but not the manure-applied field.
Biosolids are made from the sludge generated by the treatment of sewage at wastewater treatment plants. Biosolids
are used as fertilizer by farmers, landscapers, and homeowners when it satisfies U.S. Environmental Protection
Agency and local regulations for nutrient, metal, and pathogen content. About half of the 8 million dry tons of biosolids
produced in the U. S. each year are applied to the land. Biosolids have been found to be rich in AWIs compared to
levels in wastewater treatment plant effluent. In addition, the 1.3 million farms raising livestock in the U. S. generate an
estimated 500 million tons of manure annually, much of which is also applied to fields as fertilizer for crops.
This study is part of a long-term effort by the USGS Toxic Substances Hydrology Program to determine the fate and
effects of chemicals of emerging environmental concern in aquatic and terrestrial environments, and to provide
water-resource managers with objective information that assists in the development of effective water management
practices. It was funded in part by a Research Corporation Cottrell College Award and a Faculty Research Grant from
Eastern Washington University. More information can be found by reading, "Biosolids, Animal Manure, and
Earthworms: Is There a Connection?"