Residues, persistence

Water is a good choice of solvent in a standard kitchen percolator because it removes all the water-soluble components from the coffee - hence the flavour. Clearly, however, a different solvent is required if only the caffeine is to be removed. Such a solvent must be cheap, have a low boiling point to prevent charring of the coffee and, most importantly, should leave no toxic residues. The presence of any residue would be unsatisfactory to a customer, since it would almost certainly leave a taste and there are also health and safety implications when residues persist. 

The method of application has significant Impact on the amount applied per unit area and hence on residue persistence ... 

Kanamycin crosses placenta and is found in breast milk. When kanamycin was administered intramuscularly to cattle, sheep, and swine at dosages in the range 5-10 mg/kg bw at 12 h intervals, milk was free of the antibiotic 36 h after the last injection (14). However, kanamycin residues persisted longer in the kidney tissue. 

Unfortunately, streptomycin residues persist for long time at the site of injection and are also found in the kidney. Residue levels in other edible products of drug-treated sheep, pigs, and poultry were generally low and did not necessitate long withdrawal periods. 

When pigs and calves were subcutaneously given marbofloxacin, residues persisted in liver and kidney for up to 4 days posttreatment. Almost all of the residues detected in muscle and fat were due to the parent drug, whereas residues in liver and kidney were also due to drug-related metabolites as well. Residue depletion studies in dairy cows similarly treated showed that a proportion of 73-89% of the total residues in the milk was due to the parent marbofloxacin. 

In swine given radiolabeled ronidazole at the normal feed level for 3 days, total residue concentrations in muscle, kidney, liver, and fat were 8.6, 12.3, 11.9, and 2.5 ppm ronidazole equivalents, respectively, at 0 withdrawal. Total residues persisted in edible tissues by 42 days of withdrawal, at which time muscle contained 130 ppb, whereas liver, kidney, and fat contained 50-60 ppb. Nevertheless, the concentration of the parent drug in the edible tissues was less than 2 ppb at 2 days withdrawal. Ring-intact metabolites including 2-hydroxymethyl-l-methyl-5-nitroimidazole, 1-methyl-2-hydroxymethyl-5-acetamidoimidazole, and 1-methyl-2-carbamoyloxymethyl-5-acetamidoimidazole were found to constitute part of the total residues monitored in the tissues of both animal species. 

The persistence of residues at intramuscular injection sites may be due in part to the irritant response produced in the muscle (52). Chloramphenicol, tylosin, penicillins, dihydrostreptomycin, and oxytetracycline have been shown to produce local irritation at the site of injection, leading to residue persistence this may be exacerbated by the solvent used. However, residues do not persist with proper injection of drugs and use of formulations that do not cause severe irritation (52), as has been demonstrated with one oxytetracycline product that produced little irritation (53-55). 

The pharmacokinetics of FLU and its metabolite 7-OH FLU in sheep tissue was studied using the HPLC method with fluorescence detection (207). Tissue samples were extracted with ethyl acetate. After drying, phosphate buffer (pH 7.8) and hexane were added, and aqueous (lower) phase was injected into an HPLC system. Extraction recovery was 75% for FLU and 60% for 7-OH FLU. The limit of detection was 1 and 4 ytrg/kg for both compounds. The elimination of OXO in eggs (albumen, yolk) was described using an HPLC assay with fluorimetric detection. The limits of quantitation were 5 tg/kg in albumen and yolk. Of the overall oxolinic acid detected in eggs, 95% was concentrated in the albumen. Detectable residues persisted for 9 and 7 days, respectively, in albumen and yolk after the treatment was discontinued (208). Albumen sample was homogenized with water and hydrochloric acid and extracted with ethyl acetate. The supernatant was evaporated and the rest dissolved in mobile phase. Extraction recovery was 65.2%, RSD of 5.3, for a concentration of 10 ig/kg. 

Prasad, R. and J.C. Feng (1990). Spotgun-applied hexazinone Release of red pine (Pinus resinosa) from quaking aspen (Populus tremuloides) competition and residue persistence in soil. Weed Technol., 4 371-375. 

A similar behavior pattern is found in the insecticide residues in the litter-soil complex partly as a result of needle fall fenitrothion residues persist for an extended period (up to one year). Phosphamidon and aminocarb disappear very quickly. 

Results. Table III indicates that the residual persistence varied with the formulation and the substrate. Vinyl tile and painted surfaces retained residues better than glass. Bare plywood was better for M than for the EC. The RF formulation was a clear... 

Table III. Residual persistence of hydroprene formulations on various household surfaces applied at equal rates of active ingredient...

As an example of differences in soil residue persistence between the organophosphates and chlorinated hydrocarbon pesticides, parathion and malathion residues were present at the 0.1 p.p.m. level within 8 days of application whereas aldrin [according to Lichtenstein (23)] when applied at the same concentration, persisted 5 months longer as did aldrin and dieldrin at 40% of the applied dosage. Decker et al. (12) report that aldrin and dieldrin residues in soils never exceeded 13.2% of the total applied when tested one year after the last application. Other workers (24) have reported that on a loamy soil, under existing weather conditions, aldrin and dieldrin residues were present at a level of approximately 20% of the total applied insecticidal dosage over a 5-year period. 

Brozek-Mucha, Z. Chemical and morphological study of gunshot residue persisting on the shooter by means of scanning electron microscopy and energy dispersive X-ray spectrometry. Microsc. Microanal. 17, 972-982 (2011)... 

Solvolysis of (S)-2,6-dimethyloct-5-yl toluene-p-sulphonate gives a tetrahydro-linalool, (i )-2,6-dimethyloctan-6-ol, with about 60% retention of asymmetry. Kirmse and Arold have described several other similar reactions and suggest that a hydrophobic anchimeric interference of alkyl residues persists during the rearrangement, giving chirality to the carbonium ion. ... 

Residue persistence in groundwater appears to be associated with low pH and alkalinity. Groundwater pH and alkalinity increase with depth in the aquifer. High CO2 contents in the groundwater, especially in summer, tend to increase water contents of Ca and Mg by dissolution of dolomitic limestone residues from the aquifer sediments, increasing pH and alkalinity above laboratory-determined values Such conditions apparently promote chemical hydrolysis of aldicarb residues, reducing their persistence in deeper ground-water. 

Several studies with rainbow trout have examined the influence of temperature on tissue residue retention of oxolinic acid. These studies have not identified a clear temperature/residue relationship as has been identified with other compounds such as oxytetracycline (55). The range of results reported indicate greater residue persistence with colder temperatures (56), no residue-temperature dependency (57) and longer residue residence times with warmer temperatures (55). It is difficult to extrapolate between studies as dosages and experimental methods varied markedly. 

OPs and CMs arc the most commonly used pesticides throughout the world. This is partly due to their lack of residue persistence in the environment and in exposed individuals and also due to lesser resistance development in insects compared to the orgaiiochlorine pesticides. From the public health standpoint, in today s world the use of pesticides is a mu.st rather than an option. For example, sporadic incidence.s of West Nile virus are reported in many countries, whereas malaria is still a major problem in developing countries. In both cases, the common vector is the mosquito. Without the use of pesticides against vectors of diseases, the impact on human and animal health would be devastating and the economic loss would be enormous. On the one hand, the world is greatly benefited from the use of... 

Attempts are being made to reclaim large areas of natural oyster beds in the Chesapeake Bay area with 2,4-D. The ability of oysters and clams to concentrate and retain certain pesticides is well known. Shellfish and shrimp are tolerant of many herbicides when exposed to concentrations of 1 ppm (66). The adverse effects noted in a few instances disappeared rapidly. Analyses of oysters and clams taken from experimental areas showed the highest levels of 2,4-D occurred during the first few days and were lost at a fairly rapid rate thereafter. In several tests made by Thomas and Duffy (59), residues of 2,4-D in oysters ranged from 1.45 to 3.0 ppm. No residues were found after 21 days at one location however, in another location the residues persisted for 59 days. In other studies, oysters and clams accumulated maximum 2,4-D residues of 3.8 and 3.6 ppm, respectively (23). Although oysters and clams do accumulate residues of 2,4-D, the rates of elimination are such that they would cleanse themselves of the herbicide before the normal harvest season. 

It is clear from this list that consumers view products as combinations of characteristics the demand for a certain product is demand for the particular combination offered by that product. (This view of a good was first proposed by Lancaster (1966).) Three characteristics are of particular importance for this analysis price, persistence, and the absence of toxic residues. Persistence indicates a chemical s ability to accumulate in the relevant environmental compartment - water for herbicides, animal fat for... 

The limited information available suggests that aminoglycoside residues persist at trace levels in the environment (see also discussion in Chapter 3). 

The first step will be, in all cases, the establishment of an information and training in risk management. It is generally mandatory at workplace. It is also presCTibed on all packaging products for the consumer, as we explained in Sect. 5.2. Apart from the essential information, two types of preventive measures must be put in place technical collective measures and individual protective equipment. Collective actions must always be the priority. Individual measures can be conceived only when collective action leaves a residual persistent risk. 

Collective actions must always be the priority. Individual measures must be conceived only when collective action leaves a residual persistent risk. 

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