Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
During the past several years, drug residues in food animal products have become a serious problem fr livestock producers and veterinarians. The reasons for concern are threefold: first, increased sensitivity of testing methods; second, percentage of product containing residues, and third, restrictions on potential carcinogens dictated by the Delaney Amendment. The Federal government monitors foods for residues in order to provide the American people with food that is safe and unadulterated by exogenous chemicals. The use of drugs in the livestock industry today has become widespread, both as fee additives and therapeutic agents.
Trembly, Kent J.; McKean, James D.; and Lloyd, W. Eugene
"Drug Residues in Food Animals,"
Iowa State University Veterinarian: Vol. 40
, Article 2.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol40/iss2/2