Residue safety

In addition to the need for scientific improvements to allow probabilistic risk assessments to be properly performed and interpreted, there also exists a need to educate stakeholders about what the US system for tolerance establishment and monitoring does and does not do. In simplest terms, the US system can be described as a food quality system but not necessarily a food safety system. This results from the fact that the pesticide tolerances are not safety standards but rather exist as enforcement tools that allow an assessment of how well pesticide application regulations are adhered to. Violative residues demonstrate the likelihood of pesticide misuse but should not be considered, in the vast majority of cases, to represent unsafe residues. Safety considerations govern whether or not the use of pesticides on specified commodities will be permitted tolerances, when granted, serve as indicators of good agricultural practices rather than as toxicological benchmarks. 

The development of veterinary products for cattle, pigs, sheep, poultry and other food producing animals also includes residue testing of all new pharmaceutical products, including adjuvants or other excipients in vaccines. Residue safety studies address the potential risk to humans due to the consumption of food from treated animals. Accordingly, the test substances in these toxicity studies are applied orally. Residue depletion studies (pharmacokinetic studies) in the target species must be carried out to define the occurence, concentration and elimination of the substance and its metabolites in edible tissues, milk and eggs. 

The final step in the process is to create safety risk metrics for each candidate architecture. Because the system engineers on the project created hundreds of feasible architectures, the evaluation process was automated. The actual details of the mathematical procedures used are of limited general interest and are available elsewhere [59]. Weighted averages were used to combine mitigation factors and severity factors to come up with a final Overall Residual Safety-Risk Metric. This metric was then used in the evaluation and ranking of the potential manned space exploration architectures. 

By selecting and deselecting options in the architecture description, it was also possible to perform a first-order assessment of the relative importance of each architectural option in determining the Overall Residual Safety-Risk Metric. 

Evaluating residual safety tkne Evaluating available fiaictlona Trigger degradation manager... 

C3 P4 periodic self-test of the integrity of residual safety data ... 

Health and Safety Factors. Because of their high vapor pressures (methyl vinyl ether is a gas at ambient conditions), the lower vinyl ethers represent a severe fire hazard and must be handled accordingly. Contact with acids can initiate violent polymerization and must be avoided. Although vinyl ethers form peroxides more slowly than saturated ethers, distillation residues must be handled with caution. 

The scraper or knife discharge consists of a blade that removes the cake from the dmm by direct contact with the filter cake. It is normally used for granular materials with cake thickness greater than about 6 mm. In order not to damage the filter cloth, a safety distance of 1 to 3 mm between the blade and the cloth must be observed. If the residual layer is made not of filter aid but of the product, there is danger of its blocking by fine particles and by successive consoHdation by the scraper blade. 

USDA, Domestic Residue Data Book, Food Safety and Inspection Service, National Residue Program, Washington, D.C., 1992 pubHshed aimuaHy. General References... 

The 35 and 50% H2O2 concentrations are used for most industrial appHcations. The standard grades contain sufficient stabilizers to ensure safety. Grades having lower stabilizer content and evaporative residue are available for specialty uses and for aseptic cleansing of containers in food processing and marketing. 

When illegal residues have been found in monitoring studies conducted by the FDA or USD A, the reason has often been that no U.S. tolerance had been requested for that particular pesticide in that specific crop. For example, an imported crop would be deemed to be adulterated and would be seized at the port of entry into the United States if found to contain a pesticide residue in the absence of a tolerance in that crop. This is so even if tolerances have been set for the same pesticide in several crops grown in the United States and the pesticide had been used to control a pest that does not exist in the United States. Furthermore, an international maximum residue level (MRL) might already have been estabUshed for that pesticide—crop combination under the Codex system of standards for food of importance in international trade. The U.S. GAO issued two reports on food safety and pesticides in 1991 (89,90). 

Principles for the Toxicological Assessment of Pesticide Residues in Food, IPCS Environmental Health Criteria Document No. 104, International Programme on Chemical Safety, Geneva, Switzedand, 1990, 117 pp. 

A distinct concern arises in the area of veterinary dmgs because of the possibiUty that dmg residues may be conveyed to humans by the food-producing animals. Therefore, dmg residues and their safety in human food remain a central issue for the Center for Veterinary Medicine (CVM). Animal dmgs also include those products which promotional Hterature claims to improve feed efficiency and increase milk production. An animal food product is regulated under the 1968 Animal Dmg Amendments if it contains a dmg used in feed or premixes (25). 

Many more suppHers and information about their product line can be obtained from compilations such as the Modem Plastics Pmyclopedia (1) and the Thomas Register of Mmerican Manufacturers (2). The choice of a release agent depends on the process conditions involved and the nature of the contacting substrates (3). Apart from the obvious ease of release, other important requirements are minimal buildup of residues on mold substrate, minimal effect on the molded article, adequate film-forming abiHty, compatibiHty with secondary operations and other processing parameters, health and safety requirements, and cost. 

It is necessary to determine the bioburden and make cycle verification studies when ethylene oxide sterilization is used, as it is for other sterilization methods. The manufacturer of hospital sterilization equipment provides cycle recommendations based on the expected bioburden and the consideration of an appropriate safety factor. In ethylene oxide sterilization, it is necessary to determine if residues of the stefilant are absorbed by the sterilized article, and to examine the possible formation of other potentially toxic materials as a result of reaction with ethylene oxide. 

Standardization and Testing". The final vaccine is tested for safety, potency, and residual chemicals. Safety includes testing for endotoxin and stetihty. Potency is evaluated by quantitative determination of the amount of hemagglutinin in the vaccine. Antibody to this glycoprotein is associated with protection. The single radial immunodiffusion (SKID) technique is used to standardi2e the mass of this protein in comparison to a reference preparation. 

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