Environmental concerns of roxarsone in broiler poultry feed and litter in Maryland, USA.

Roxarsone has been used extensively in the broiler chicken industry. We reviewed the environmental concerns of this usage. To summarize, arsenic added to poultry feed as roxarsone ends up in poultry litter. Fresh litter contains predominately roxarsone, whereas aged litter contains predominately inorganic arsenic. Soil arsenic concentrations from long-term poultry litter applications can exceed Maryland arsenic soil background remediation standards. Due to continued soil accumulation, arsenic-amended litter use as fertilizer is thought to be unsustainable. Surface-applied roxarsone-amended litter does not influence deep aquifer arsenic concentrations but is transported as inorganic arsenic to receiving waters and very shallow groundwater after precipitation. Arsenic in some receiving waters and sediments from agriculturally dominated watersheds have levels above established criteria. Arsenic in fish and shellfish is mostly organic. Phosphorus-based nutrient management will tend to limit PL application rates in areas that have over-applied phosphorus relative to crop needs, resulting in decreased rates of arsenic application and accumulation. Despite most arsenic in surface soils being tightly bound, as surface soils become more enriched in arsenic, the potential for downward movement increases but is limited in most soils due to the high capacity for binding of arsenic to clay minerals and oxides of iron and aluminum in subsoil horizons. In 2012, Maryland passed a law banning the use of arsenic additives except nitarsone in poultry feed. In 2013, the USFDA withdrew approval of roxarsone, carbarsone, and arsanilic but is reviewing nitarsone.

Poultry litter-induced endocrine disruption in fathead minnow, sheepshead minnow, and mummichog laboratory exposures.

Animal feeding operations in the United States produce more than 500 million tons of manure annually. Disposal of poultry waste via application as fertilizer results in substantial runoff of poultry litter-associated contaminants (PLAC). Of particular concern are sex steroids, 17ß-estradiol, estrone and testosterone, responsible for sex differentiation and development of reproductive structures. In a series of laboratory assays, mature male and mixed-sex larval/juvenile fish were continuously exposed to environmentally relevant PLAC solutions. Effects on gonads were assessed histologically, and vitellogenin (VTG) induction was measured as a gauge of estrogenicity. Twenty-one-day exposures to laboratory-generated PLAC solutions routinely induced VTG in mature male Pimephales promelas. Vitellogenesis in Fundulus heteroclitus only occurred at the highest tested PLAC concentration, and Cyprinodon variegatus were unresponsive at any tested concentration. All species produced considerable VTG in response to a 17ß-estradiol-positive control. A pronounced feminization was seen in P. promelas when exposed to PLAC as larvae but not when exposed as juveniles. Runoff from a poultry litter-amended field cropped under standard agronomic practices induced significant VTG in male P. promelas. Results indicate that environmentally relevant PLAC concentrations exhibit endocrine activity sufficient to induce VTG production in male fish and possibly affect sex ratios in resident fish populations.