Metabolite pesticide

A possible example of this thesis is the crystalline insect toxin found in Bacillus thuringiensis spores and discussed here by Dr. Anderson. Although neither the bacillus nor its spores exhibit useful antibiotic activity against other microorganisms, the very specific toxicity to insects has become of major commercial interest. The enormous number and variety of fungal species available for further examination must lead inevitably to one or more which produces pesticidal metabolites. 

Pesticides and pesticide metabolites e. g. aniline and urea derivatives [4]... 

In recent years greater attention has been given to nitrogen containing pesticides and the possibility of their nitrosation in soil. The N-nitrosamines that form may arise from the parent pesticide or from a pesticide metabolite. The reaction calls for favourable pH conditions (pH 3-4) and excess nitrite. Under field conditions, the nitrosable residues are usually present in traces and only small quantities of these will actually be nitrosated in soils. However, the possibility exists that the small amounts of N-nitrosamines could be assimilated by plants. 

Division of Research and the University of Califomia-San Francisco School of Medicine (Cohn et al., 2003). They measured pesticide metabolites in preserved postpartum maternal serum samples from 1960 to 1963. They also recorded time to pregnancy in their eldest daughters 28-31 years later. The daughters probability of pregnancy fell by 32% for each 10 mcg/1 detected, three decades after the exposure. 

Fujisawa T, Kurosawa M, Katagi T (2006) Uptake and transformation of pesticide metabolites by duckweed (Lemna gibba). J Agric Food Chem 54 6286-6293... 

Thust, R., Mendel, J., Schwarz, H. and Warzoki, R. (1980). Nitrosated urea pesticide metabolites and other nitrosamides. Activity in clastogenicity and SCE assays, and aberration kinetics in Chinese hamster V79-E cells. Mutation Res. 79 239-248. 

Suprock JF, Vinopal JH. 1987. Behavior of 78 pesticides and pesticide metabolites on four different ultra-bond gas chromatographic columns. J Assoc Off Anal Chem 70(6) 1014-1017. 

In many cases, the U.S. tolerances and the Codex MRLs are similar, although there are other cases where they may be quite different. When U.S. tolerances and Codex MRLs can be compared directly, 47% have been shown to be equivalent, 34% of Codex MRLs were found to be lower (more restrictive), and 19% of U.S. tolerances were lower (General Accounting Office, 1991). There are a number of reasons that explain the differences these include the use of different data sets, different methods to regulate pesticide metabolites, and different agricultural production and pest control practices. 

The majority of samples taken in the FDA monitoring program are from imported foods, which constitute approximately two thirds of all the samples taken. Imports are typically sampled at the point of entry into the U.S., while domestic samples are frequently collected close to the production source or at the wholesale level. Samples are usually analyzed using multiresidue techniques capable of the detection of approximately 200 pesticide active ingredients as well as several other pesticide metabolites, impurities, and alteration products. 

Kissel, J.C., C.L. Curl, G. Kedan, C. Lu, W. Griffith, D.B. Barr, L.L. Needham, and R.A. Fenske. 2005. Comparison of organophosphorous pesticide metabolite levels in single and multiple daily urine samples collected from preschool children in Washington State. J. Expo. Anal. Environ. Epidemiol. 15(2) 164-171. 

HODGSON, E., Production of pesticide metabolites by oxidative reactions. J. Toxicol. Clin. Toxicol., 1982,19,609-621. 

Biosensors differ from bioassays mainly by the fact that in bioassays the transducer is not an integral part of the analytical system and biosensors can extract quantitative analytical information of single compounds in complex mixtures. One example is the determination of concentrations of dioxin-like compounds in the blood and environmental samples using the Calux assay, where within a complex matrix its levels are determined with great accuracy (see, e.g., Murk et al. 1997). Additionally, compounds that are difficult to detect (e.g., surfactants, chlorinated hydrocarbons, sulfophenyl carboxylates, dioxins, pesticide metabolites) can more easily be evaluated using biosensors. 

A study in Washington State found that children living with agricultural workers and in proximity to tree fruit orchards may have more opportunity for exposure than children living in homes without such risk factors (Simcox et al., 1995). These findings were supported by an additional study which measured pesticide metabolites in children s urine (Loewenherz et al., 1997 Lu et al., 2000). 

Measurement of pesticide metabolites in nrine holds the potential for developing a more accurate estimate of internal dose, and is particnlarly nsefnl when exposnre is from multiple routes, oral, as well as respiratory and dermal, as is almost always the case for pesticide-exposed workers. If the total nrinary ontput is collected, until either there are no detectable residues or background levels are reached (usually 48-96 h), the levels can be used to estimate the internal dose. Stndies carried out in animals and humans for several pesticides have shown a good correlation between the amount of pesticide applied to the skin and the urinary output (Franklin et al., 1983, 1986 Popendorf and Eranklin, 1987). However, there are limitations to using this approach. The pharmacokinetics of the pesticide must be known in humans, while those pesticides that are highly volatile are extensively metabolized to numerous minor metabolites or seqnestered and are... 

Franklin, C.A., R.A. Fenske, R. Greenhalgh, L. Mathieu, H.V. Denley, J.T. Leftingwell and R.C. Spear (1981). Correlation of urinary pesticide metabolite excretion with estimated dermal contact in the course of occupational exposure to Guthion, J. Toxicol. Environ. Health, 7, 715-731. 

Rauch, S.A., Braun, J.M., Boyd Barr, D., Calafat, A.M., Khoury, J., Montesano, M.A., Yolton, K., Lanphear, B.P. Associations of prenatal exposure to organophosphate pesticide metabolites with gestational age and birth weight. Environ. Health Perspect 120, 1055-1060... 

T Tnequivocal identification of pesticides, pesticide metabolites, and other chemical environmental pollutants in most cases requires more evidence than can be provided by a single chromatographic method. Several approaches may be utilized to secure firm proof of identity. For example, supportive chromatographic data such as relative retention... 

An additional obvious advantage would be the characterization and identification of frequently encountered, unknown components of extracts, which may represent pesticidal metabolites, photochemical and other weathered residues, nonpesticidal chemical pollutants, or co-extractive interferences whose identity may be required. 

The first section of this book describes the application of LC/MS to the analysis of agricultural chemicals and their metabolites. Using LC/MS for residue analysis in agricultural chemistry has become routine in many laboratories. Many pesticides, such as the chlorophenoxy acid and sulfonyl urea herbicides or organophosphorus and methyl carbamate insecticides, are too polar or thermally labile for analysis via GC. The use of LC/MS for the identification of polar pesticide metabolites and conjugates, an area traditionally dominated by radiolabeled compounds, stands out as a particularly dramatic demonstration of the power of this technique. 

Hill RH, Jr, Shealy DB, Head SL, Williams CC, Bailey SL, Gregg M, et al. Determination of pesticide metabolites in human urine using an isotope dilution technique and tandem mass spectrometry. J Anal Toxicol 1995 19 323-9. 

When the products formed by metabolic processes are toxico-logically insignificant and, when this is a known fact, the findings may be valuable in assessing pesticide risk. Contrarily, a number of pesticides yield metabolites known to be highly toxic and these materials may be taken into account in the risk assessment process. Too many times, however, the isolation and identification of pesticide metabolites tell us very little about risks that may be associated with the use of a particular chemical because the information can not be related to in vivo toxicological significance. 

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