Produce violative residues

Table 13.7 provides information on the antibiotic and sulfonamide violations detected during 1992-1994. Sample sizes differed in the various animal slaughter classes in different years. Thus, it would not be appropriate to attribute undue significance to the number of violations detected of an individual compound. Table 13.7 does provide relevant information about the specific compounds that produced violative residue concentrations in food animals during that period. Residue violations for more than one compound might occasionally occur in the same animal. 

Table 14.5 provides a sense of how frequently the PDP might need to alert the NOP of a violative residue in an organic sample. The table shows all positive samples of fresh organic produce in 2004, the residue level found and the applicable EPA tolerance. The PDP would need to flag any value over one in the column Ratio of residue found to 5% of EPA tolerance ... 

The number of animals sampled compared with the numbers produced will always astound the reader as relatively few animals are normally sampled and analyzed. It is impossible from both a logistical and cost point of view to sample huge numbers of animals. To accomplish a reasonable sampling program, an experience-based approach is both logical and realistic. This approach bases the sample size (number of animals analyzed) on what experience has shown the incidence of violative residues to be in that class of animal. Where a high incidence of violative residues is expected, a smaller number of samples is needed. 

In the enforcement phase of testing, IDA may also conduct follow-up investigation at the animal producer level to uncover the original source and cause of the contamination problem. This often results to seizure of animal feed or seizure and condemnation of carcasses. In accordance with the federal law, offenders may face prosecution if found guilty of contravening FDA tolerance levels. In addition, farmers harboring violative residues may find future shipments impounded unless they can clearly demonstrate compliance with residue standards. 

The use of drugs in food-producing animals inevitably results in the appearance of drug-related residues in milk, meat, and eggs. Antimicrobial residues occur more frequently than desired violative residues occur much less frequently, but in definitely significant numbers. 

The residue profile seen over the years 1976-1978 is similar to that seen in the following years. Table 13.2 lists the violative residue rates for antibacterials in several animal species for the years 1979-1983. The residue violation rate in mature cattle and poultry was very low. Chickens, in particular, had almost a zero violation rate due possibly to highly integrated US chicken-producing operations. In addition, the violation rate for turkeys was still very low although turkeys were mostly raised by independent producers. 

Between May, 1986, and December, 1990, over 35,000 analyses were conducted in the United Kingdom for surveillance for veterinary drug residues in food. The results drawn from these analyses allow the incidence and concentrations of drug residues in the national food supply to be assessed (29). Although a very large number of samples were analyzed, a rather small number of samples were found to contain violative residues that mainly concerned sulfonamides in swine, and oxolinic acid and oxytetracycline in farmed fish. However, the incidence of sulfonamide residues in a range of swine tissues from home-produced and imported sources showed a significant decline over the period 1986-1990 (Table 13.21). 

An overview of the results of the Canadian Veterinary Drug residue control program during the fiscal years 1990/1991-1994/1995 shows that all meat and poultry commodities produced or imported during that period in Canada were totally free of violative residues of many veterinary drugs including chloramphenicol, benzimidazoles, nitrofurans, coccidiostats, zeranol, diethylstilbestrol and... 

Failure to abide by the approved label instructions is by far the leading cause of illegal residues detected in edible animal products. Noncompliance with proper withdrawal periods was responsible for 46% and 54% of the cases of violative residues monitored in the fiscal years 1990 and 1991, respectively, in the United States. Failure to comply with approved withdrawal periods was also identified as the most common cause of the drug violations monitored in the fiscal year 1993 by the Food Safety and Inspection Service of the Food and Drug Administration (FDA). Livestock species producing most violations were the bob veals, with approximately 40%, followed by cull cows with 30%. 

In residue surveys, tissue samples are also collected at random to be submitted to routine testing. If a violative residue is found, the producer is notified and the animals are held in the farm, and tested until they are proven to be residue-free. To provide this proof, producers are allowed to submit a small number of animals for residue evaluation. The marketing status of the producer is reevaluated based on the tissue test results. The carcasses are retained usually for 14-30 days until the test results are available and will be condemned if the results indicate the presence of violative residues. In many cases, producers incur additional expenses for the packer to debone, freeze, and store the retained carcasses. 

Even when no violative residues are found, the carcasses usually depreciate in value a great deal while awaiting the test results. To reduce testing time, the producers may apply to an approved laboratory to have the samples analyzed at their own expense. In the event a violative residue is found, the producer has to submit another group of animals for residue evaluation. This procedure may be repeated until analysis data of tissue samples indicate a residue-free status. In the meantime, the livestock producer is often confronted with increased production costs due to overcrowding caused by inability to market the animals on a timely basis. In addition, weight gains are slowed, feed efficiency becomes poorer, and the value of the product is lowered because of accumulation of excessive finish. 

Post-AMDUCA, veterinarians are permitted to prescribe extralabel uses of approved drug. " The key constraints are that any extralabel use must not result in violative residues in food-producing animals, the use must be by or on the order of a veterinarian within the context of a veterinarian-client-patient relationship, and the use must be in conformance with the new regulations, including the exclusion of compounds prohibited from extralabel use in food-producing animals. ... 

Rapid progress has been reported in the development of methods for sulfonamide residues in tissues, milk, and eggs since the subject was reviewed by Horwitz ( ) in 1981, The colorimetric method of Tishler et al (j ) has in the past been used to detect violative levels of sulfonamide residues in animal tissues. The lack of specificity and the variable background levels produced by this method have been discussed by Horwitz ( ), Matusik et al (15), and Lloyd et al (16), Recently, a number of specific chromatograpiic methods have been described for determination of residues of a variety of sulfonamides, These are summarized in Table 1 and suggest that HPLC is emerging as the method of choice followed by GLC and TLC methods. 

Residues have the potential to cause significant monetary losses to livestock industry. The livestock producer can have direct financial losses from violative drug residues through condemnations of carcasses at slaughter, rejection of milk, increased production costs, test costs, and regulatory action. 

Detection of a violative drug residue is always a disaster that threatens the smaller milk producer much more than the large producer. Recently a veterinarian that consulted with 130 herds with 150,000 cows indicated to the US Dairy Quality Assurance center that none of the herds had a violative load of milk in over 6 months. In contrast, an insurance company that insures smaller dairies reported that 10% of their 9000 clients had a claim in over 12 months. 

Correct interpretation of the analytical results in the field of residue analysis is a matter of major importance. Truly positive, false-violative, false-positive, falsenegative, and truly negative are all types of test results that may be produced during food monitoring for drug residues. Truly positive is a positive test result... 

Violative tabulated as those over tolerance or detected if no tolerance established. Produce categories do not exactly match in listings for residues versus utilization. 

Agonists are synthetic compounds that, in addition to their therapeutic use in veterinary medicine, are able to promote live weight gain in food-producing animals. Such a use, however, may result in the presence of residues in the edible products of treated animals that may cause a real health problem to consumers. An overview of the isolation, separation, quantification, and confirmation procedures that may be used to analyze for violative (3-agonist residues in foods is presented in this entry. 

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