Pesticides, classes

Compound CAS Registry Number Molecular formula Pesticide class... 

Pesticide Classes Pesticides Studied % Mutagens Observed... 

Fig. 2 Relative concentration of (a) pesticide classes in each aquifer and (b) total pesticides in each sampled year and aquifer...

Available at http //www.alanwood.net/pesticides/class pesticides.html Yaalon DH, Yaron B (1966) Framework for man made soil changes—outline of metapedogenesis. Soil Sci 102 272-276... 

Repeat-dose neurotoxicity studies may identify behavioral effects or impaired nerve functions that can interfere with mating or maternal care. Developmental neurotoxicity studies have been conducted for specific pesticide classes, following requirements of US-EPA. If such a study is available it can be examined not only for the study-specific endpoints on the developing brain but also compared to the prenatal toxicity study and the two-generation smdy with respect to general endpoints of pre- and postnatal development, respectively. 

Model of Bahnick and Doucette Molecular connectivity indices have been applied to establish structure-soil water partitioning relationships for various classes of compounds. Bahnick and Doucette [22] briefly review such models and present a new model for a variety of organic compounds, including halogenated alkanes, PAHs, chlorobenzenes, PCBs, and different pesticide classes. The model is... 

Of these 86, 47 were fieldworker reentry incidents (Table I). Nine states reported incidents. California had the highest number with 34 incidents, followed by North Carolina with 3. Sulfur led with 9 cases and parathion was involved in 6. All the sulfur cases were from California, usually involving eye irritation. Twenty-five different pesticides, covering all pesticide classes, were implicated in these reported incidents (Table II). But this summary must be judged incomplete as the... 

Call for a phase-out of pesticides classed by the World Health Organisation as being either Extremely Hazardous (WHO la) or Highly Hazardous (WHO lb) as well as the organochlorine endosulfan (WHO 11) ... 

Pesticide Class U.S. Market MOlion % World Market MiHion % U.S. % of World Market... 

Herbicides are the most important pesticide class in terms of production volume and market value. In agriculture they are used to control weeds. Weeds are unwanted plants, such as grasses, sedges, and broadleaf plants, that compete with the desired crop plants for nutrition, water, and land, thereby reducing the yield. Herbicides also have nonagricultural uses as they help in erasing vegetation on streets, railroad tracks, sports fields, and other public areas. 

Many papers on the LC-MS analysis of pesticides and related compounds deal with the characterization of interface and ionization performance, the improvement of detection limits by variation of experimental conditions, and the information content of the mass spectra. As far as ESI and APCI ate concerned, this type of information is reviewed for various pesticide classes in this section (see Ch. 4.7.4 for results with thermospray and Ch. 5.6.1 with particle-beam interfacing). 

Biotransformation of certain chlorinated hydrocarbon insecticides results in their conversion to metabolites which are less polar than the parent chemical. Heptachlor and aldrin are converted to the more lipophilic compounds heptachlor epoxide and dieldrin, respectively, whereas DDT is converted to DDE. The primary residue of DDT, which persists to the present day in animals and humans after exposure over a decade ago, is DDE. Following biotransformation, these compounds distribute to tissues which are higher in neutral lipid content than are the major organs of metabolism and excretion, the liver and kidney. These lipid-rich tissues are relatively, deficient in the so-called mixed-function oxidase (MFO) enzyme systems necessary for biotransformation of the halogenated hydrocarbons to more polar and thus more easily excreted compounds. As a result, these lipophilic chemicals remain unchanged in adipose tissue with only limited amounts returning to the circulation for possible metabolism and excretion. Paradoxically, aldrin and heptachlor metabolism results in an increased rather than reduced body load. This is opposite of the pattern seen for most other pesticide classes. 

The next papers discuss another observation that various sexual abnormalities have been observed in wild populations of some toads, fish, and other reptiles. A link is then postulated that chemicals must be the cause of both. The argument is broadened when some pesticide classes are then thought to be partially responsible for breast cancer in women. 

Table 2-6 Estimated Range of Sediment/Water Partition Coefficients for Various Pesticide Classes (after Pavlou Dexter, 1980)...

Immunoaffinity sorbents (ISs) are more selective compared to ODS sorbents. The first commercial ISs were introduced for the cleanup of samples for the determination of aflatox-ins (Groopman and Donahue, 1988). ISs have been synthesized for a limited number of pesticides and pesticide classes. Immunosorbents arc formed by covalently bonding antibodies to an appropriate sorbent. Immunosorbent is packed into a solid phase extraction cartridge or precolumn as a classical extraction sorbent (Bouzige and Pichon, 1998). There is much interest in developing ISs for single analytes, which are particularly difficult to analyze at the trace level because of a lack of available extraction methods,. such as acephate and methamidophs. 

An extensive body of literature has been published with respect to the quantitative analysis of TPs of pesticides in air [27,28], surface waters [29,30], groundwater [31,32], sediment [33,34], and soil [35,36] and several critical reviews on existing methods have been recently pubhshed [37,38]. A number of multiresidue methods have been developed for the determination of parent compounds and TPs covering a wide range of pesticide classes [37]. Compounds that are typically included into monitoring programmes are organochlorines DDT and its TPs DDE and DDD endosul-fan, endrin, and heptachlor and their TPs triazine herbicide atrazine and its TPs deethylatrazine and deisopropylatrazine chloroacetanilide herbicides and their acidic TPs. 

To undertake an assessment of the different approaches an experimental ecotoxicity data set was generated by randomly selecting fifty transformation products from the daphnid data set described previously. An assessment of the predictive performance of five techniques was undertaken by comparing predictions from each approach to the experimentally determined data. The data set included transformation product ecotoxicity data from a range of pesticide classes, i.e. insecticides, herbicides and fungicides and chemical classes, e.g. organophosphorus insecticides, sulfonylureas and azoles. 

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