Past usage

Possible releases of heptachlor to soil may occur at hazardous waste sites or as a result of landfill leachate. Residues of heptachlor or heptachlor epoxide exist in soil as a result of past usage of heptachlor for both agricultural and nonagricultural purposes. Heptachlor was detected in 0.71% of the soil samples taken from the NPL sites included in the CLPSD at an estimated mean concentration of 4.07 ppb in the positive samples (CLPSD 1989). Heptachlor epoxide was not listed in the CLPSD of chemicals detected in soil samples collected at NPL sites. Note that the information from the CLPSD includes data from NPL sites only. 

Avoid interference from past usage of pesticides... 

The formulae — CH2-CH2- and CF2"CF2") are more often used they are acceptable owing to past usage and an attempt to retain some similarity to the CRU formulae of homopolymers derived from other vinyl monomers. 

Past usage. Pharmacy managers should review drug usage reports and new and refill prescription orders to determine what to stock. 

The only past usage in the field of agriculture has been the use of Z. I. P., the zinc salt of dimethyldithiocarbamic acid compound with cyclohexylamine, to keep deer, rabbits, and other rodents from feeding on the bark and twigs of dormant trees in the winter. It cannot be used on the foliage because of phytotoxicity. 

The sad experience with the conditions at IBT, where multiple studies were run simultaneously in the same room with the concomitant problems of mix-ups of animals and treatment cross-contamination by volatile test substances, have resulted in the requirement of sufficient space to assure the isolation of test systems . Through a sufficient number of rooms or at least sufficiently separable areas, it should become possible to avoid any crosscontaminations or mix-ups of projects, tests or treatments. Also the positioning of test systems used in field studies requires an appropriate degree of separation, as it is specified in the GLP Principles ( Test systems used in field studies should be located so as to avoid interference in the study from spray drift and from past usage of pesticides . In the same sense, isolation of individual projects in aquatic toxicity testing should be applied to the extent necessary, to prevent cross-contamination through spray, mist or overflow. 

Test systems used in field studies should be located so as to avoid interference in the study from spray drift and from past usage of pesticides. 

Tools should be used since they relieve staff from manual error prone tasks such as programming and verification. They help to achieve a reproducible level of quality, in part guaranteed and demonstrated by the evidence provided by their past usage. 

Feedback on the in-service behaviour of software may provide confidence in its ability to perform its desired functions in addition to other verifications. If such information is to be used, then an analysis of the relevance of its past usage, especially its compatibility with the proposed new enviromnent and the relevance to the proposed new application, should be provided. 

Unfortunately, most companies still rely on past-usage as a proxy for future demand. Such approaches suffer from deficient end-user demand data as it may hide the causes leading up to this data, ignorance of customer buying patterns and market potential, and inability to access actual demand at the point-of-sale. Clearly, the demand assessment approach needs to be broadened. 

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