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[SANET-MG] arsenic in animal waste managment

July 8, 2005
Prof. Joe Cummins
Arsenic in animal waste management
The abstracts of two publications are given below. The first publication deals with the problems of waste management in the face of arsenical pharmaceuticals in animal feed. The second article describes a common arsenical used to treat chickens for parasites. Arsenic is known to be a human carcinogen, even at very low level in the water supply or diet. The problem facing organic farmers is knowing their compost source, I believe. However, I would appreciate comments on animal waste, arsenic and compost in organic farming.
Arsenic—a roadblock to potential animal waste management solutions
Keeve E. Nachman, Jay P. Graham, Lance B. Price,and Ellen K. Silbergeld
doi:10.1289/ehp.7834 (available at http://dx.doi.org/)
The localization and intensification of the poultry industry over the past 50 years has incidentally created a largely ignored environmental management crisis. As a result of these changes in poultry production, concentrated animal feeding operations produce far more waste than can be managed by land disposal within the regions they are produced. As a result, alternative waste management practices are currently being implemented, including incineration and pelletization of waste. However, organic arsenicals used in poultry feed are converted to inorganic arsenicals in poultry waste, limiting the feasibility of waste management alternatives. The presence of inorganic arsenic in incinerator ash and pelletized waste sold as fertilizer creates opportunities for population exposures that did not previously exist. The removal of arsenic from animal feed is a critical step towards safe poultry waste management. Environ. Sci. Technol., 37 (8), 1509 -1514, 2003. 10.1021/es026219q S0013-936X(02)06219-3 Environmental Fate of Roxarsone in Poultry Litter. I. Degradation of Roxarsone during Composting J. R. Garbarino,* A. J. Bednar, D. W. Rutherford, R. S. Beyer, and R. L. Wershaw
Roxarsone, 3-nitro-4-hydroxyphenylarsonic acid, is an organoarsenic compound that is used extensively in the feed of broiler poultry to control coccidial intestinal parasites, improve feed efficiency, and promote rapid growth. Nearly all the roxarsone in the feed is excreted unchanged in the manure. Poultry litter composed of the manure and bedding material has a high nutrient content and is used routinely as a fertilizer on cropland and pasture. Investigations were conducted to determine the fate of poultry-litter roxarsone in the environment. Experiments indicated that roxarsone was stable in fresh dried litter; the primary arsenic species extracted with water from dried litter was roxarsone. However, when water was added to litter at about 50 wt % and the mixture was allowed to compost at 40 C, the speciation of arsenic shifted from roxarsone to primarily arsenate in about 30 days. Increasing the amount of water increased the rate of degradation. Experiments also suggested that the degradation process most likely was biotic in nature. The rate of degradation was directly proportional to the incubation temperature; heat sterilization eliminated the degradation. Biotic degradation also was supported by results from enterobacteriaceae growth media that were inoculated with litter slurry to enhance the biotic processes and to reduce the concomitant abiotic effects from the complex litter solution. Samples collected from a variety of litter windrows in Arkansas, Oklahoma, and Maryland also showed that roxarsone originally present had been converted to arsenate.

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