title: What do we feed to food-production animals? A review of animal feed ingredients and their potential impacts on human health.
abstract: OBJECTIVE
  Animal feeding practices in the United States have changed considerably over the past century. As large-scale, concentrated production methods have become the predominant model for animal husbandry, animal feeds have been modified to include ingredients ranging from rendered animals and animal waste to antibiotics and organoarsenicals. In this article we review current U.S. animal feeding practices and etiologic agents that have been detected in animal feed. Evidence that current feeding practices may lead to adverse human health impacts is also evaluated.
  
  
  METHODS
  We reviewed published veterinary and human-health literature regarding animal feeding practices, etiologic agents present in feed, and human health effects along with proceedings from animal feed workshops.
  
  
  METHODS
  Data were extracted from peer-reviewed articles and books identified using PubMed, Agricola, U.S. Department of Agriculture, Food and Drug Administration, and Centers for Disease Control and Prevention databases.
  
  
  RESULTS
  Findings emphasize that current animal feeding practices can result in the presence of bacteria, antibiotic-resistant bacteria, prions, arsenicals, and dioxins in feed and animal-based food products. Despite a range of potential human health impacts that could ensue, there are significant data gaps that prevent comprehensive assessments of human health risks associated with animal feed. Limited data are collected at the federal or state level concerning the amounts of specific ingredients used in animal feed, and there are insufficient surveillance systems to monitor etiologic agents "from farm to fork."
  
  
  CONCLUSIONS
  Increased funding for integrated veterinary and human health surveillance systems and increased collaboration among feed professionals, animal producers, and veterinary and public health officials is necessary to effectively address these issues.
authors.affiliation: Johns Hopkins Center for a Livable Future, Bloomberg School of Public Health, Baltimore, Maryland, USA. amy@amysapkota.com
authors.forename: Amy R
authors.initials: AR
authors.lastname: Sapkota
authors.forename: Lisa Y
authors.initials: LY
authors.lastname: Lefferts
authors.forename: Shawn
authors.initials: S
authors.lastname: McKenzie
authors.forename: Polly
authors.initials: P
authors.lastname: Walker
mesh_terms: D000821:Animal Feed / Q000032:analysis* / Q000382:microbiology*; D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D000829:Animals, Domestic; D001152:Arsenicals / Q000032:analysis; D001419:Bacteria / Q000302:isolation & purification; D004147:Dioxins / Q000032:analysis; D005506:Food Contamination / Q000032:analysis*; D011159:Population Surveillance / Q000379:methods*; D011328:Prions / Q000032:analysis; D012307:Risk Factors; D014481:United States
chemical_list: D001152:Arsenicals; D004147:Dioxins; D011328:Prions