USDA tolerance setting

CMA), and the USDA are excellent sources of information relative to current regulatory activities which will impact both production agriculture and the setting of tolerances to ensure food safety. The purpose of this article is to summarize the key impacts of the 1996 OPPTS 860 Residue Chemistry Test Guideline series as they impact research associated with field production of RAC samples to be used in establishing safe tolerance limits for pesticides used in commercial agricultural production. 

The Federal Food, Drug, and Cosmetic Act (FFDCA) deals mainly with pesticide tolerance. Pesticide tolerances are set by the EPA and enforced by the FDA or, in the case of meat, milk, poultry, and eggs, by USDA agencies. 

Analytical Methods for Residues. After the marker residue and target tissue have been identified and a tolerance level or Rm has been set, the sponsor develops determinative and confirmatory methods for the marker residue at the tolerance. The determinative method must be practical and rugged to be useful for routine surveillance monitoring of residues in meat in USDA field laboratories. The confirmatory method is one in which the marker residue is determined unequivocally so that the identity of an above tolerance residue can be supported in a court of law. Methods that are capable of this level of specificity often employ mass spectrometry in one form or another. 

Listeria spp. is probably one of the most seriously treated food-borne pathogens due to its ability to cause listeriosis, a condition with flu-like symptoms which can compromise the human immune system especially in pregnant women, children and the elderly. Mortality rates from full listeriosis are at 20% prompting the USDA and FDA to set a "zero tolerance" against the pathogen. Detection of this microbe is therefore more important than enumeration. In food. Listeria spp. can grow even at refrigerated temperatures and have been isolated from meat and cheese products. 

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