Assessment of human health risks resulting from exposures to arsenic during the use of pelletized poultry house waste and human biosolids fertilizers

Managers of human biosolids have been incorporating the practice of waste pelletization since the mid 1920's, and waste pelletization has recently been embraced by some poultry producers as a way to move nutrients away from saturated farm land. This management strategy facilitates the off site transport and sale of pelletized wastes as fertilizers for home and commercial lawns and gardens. However, arsenical drugs used in poultry production and found in poultry house waste (PHW), as well as the lack of characterization of arsenic concentrations in treated sewage sludge raise concerns for potential human exposures to arsenic that may arise from use of pelletized waste fertilizers. The purpose of this dissertation was to characterize carcinogenic risks and non-carcinogenic hazards resulting from human exposures to arsenic during the use of pelletized PHW (PPHW) and human biosolids fertilizers.; Arsenic concentrations were determined in PPHW and pelletized biosolids fertilizer (PBF) samples. Pellets were processed using strong acid microwave digestion and analyzed by graphite furnace atomic absorption spectroscopy. The mean arsenic concentration in PPHW (20.1 ppm) fell within the lower part of the range of previously report arsenic concentrations in unpelletized PHW and was within the range of preliminary data provided by the Chesapeake Bay Foundation. Arsenic concentrations in PBF were approximately a factor of 5 times lower than those in PPHW, with a mean concentration of 4.1 ppm.; The results of the arsenic analyses were incorporated into a comparative multipathway probabilistic risk assessment to evaluate human exposures to arsenic resulting from the use of pelletized PHW and biosolids fertilizers. For adults, risks resulting from application and post-application exposures were assessed. For children, post-application exposures as well as the pica child scenario were characterized. It was determined that the maximum reasonable estimate (MRE) for adult carcinogenic risk from use of PPHW exceeded the upper limit of acceptable risk range presented in the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). The MRE resulting from use of PBF was close to, but did not exceed the acceptable risk range. It was determined that non-carcinogenic effects were not expected to occur in the adult or child receptor as a sole result of exposures to either PPHW or PBF. Results from evaluation of the pica scenario indicated the potential risk for facial edema and gastrointestinal effects in children consuming PPHW, but not PBF.; The findings of this research indicate that exposures to arsenic in PPHW may be of concern, and that removal of arsenical drugs from poultry feed could eliminate these and other environmental and dietary exposures to arsenic. Also highlighted by this research is the need for screening of biosolids intended for use as pelletized fertilizer. Finally, as indicated by the incremental arsenic risks presented in this study, research is needed to formulate a more comprehensive approach to arsenic regulation that takes into account the multifaceted nature of human arsenic exposures.