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Pesticides mixtures, environmental transformation

Mixtures of Pesticides and Their Environmental Transformation Products. 217... [Pg.205]

The second case refers to hormones, pharmaceuticals, and other compounds that are ingested, metabolized, and excreted by mammals (Table 1). Usually a hormone or pharmaceutical is extensively metabohzed in the body and is excreted by mammals as a mixture of different metabolites. Although the general belief is that metabolism renders a drug more water soluble and consequently less hazardous for the aquatic environment, there are exceptions for pro-drugs and specifically acting metabolites. The third case refers to environmental transformation products of pesticides and other environmental pollutants (Table 1), which are formed both by abiotic and biotic transformation processes. [Pg.208]

Since the production of PCBs ceased in the late 1970s in North America and Europe, current atmospheric sources of PCBs are believed to be predominantly from volatilization from contaminated environmental surfaces such as soil [312-314] and water [291, 315]. However, emission from existing PCB technical mixtures (i.e. capacitors, transformers, constmction materials) may also contribute to atmospheric contamination [316, 317]. The use of PCB atropisomers for source apportionment was first demonstrated by Robson and Harrad [182], who observed that nonracemic soil EFs for PCBs 95, 136, and 149 were statistically different from racemic EFs of all three congeners in the overlying air. In contrast to chiral OC pesticides, the source of atmospheric PCBs was thus not due to volatilization from the sod, but from emission of unweathered PCBs remaining in use. In subsequent work [318], PCB concentrations of indoor air in the West Midlands of the UK had not changed significantly over the past 10 years. Both indoor and outdoor air had... [Pg.113]

Whereas studies on the environmental photochemistry of the majority of pesticides have been conducted extensively, few data exist for PPCPs. Pharmaceuticals are mainly polar compounds containing acidic or basic functional groups (such as carboxylic acids, phenols, and amines) that may be subject to direct and indirect photolysis. Although microbial degradation in waters and soil has been reported for pesticides, less work is reported for PPCPs. The result of such processes can be a complex mixture of reactive intermediates and TPs. Their identification represents a more challenging task than the identification of transformation products stemming from microbial transformation, for which at least some common mechanisms are well established. Therefore, the application of advanced instrumental techniques is of crucial importance. [Pg.49]

Mixtures of OP Compounds In many cases of environmental contamination with OP pesticides where a rapid screening assay would be of value, samples may be expected to contain multiple pesticides. These compounds may be present as parent compounds as well as various oxidative transformation products. Data from Table IV suggest that for mixtures of OP and carbamate insecticides, the most potent AChE inhibitors would dominate the results of the inhibition assay. [Pg.301]


See other pages where Pesticides mixtures, environmental transformation is mentioned: [Pg.172]    [Pg.206]    [Pg.240]    [Pg.209]    [Pg.1236]    [Pg.168]    [Pg.192]    [Pg.104]    [Pg.96]    [Pg.13]    [Pg.950]    [Pg.202]    [Pg.814]    [Pg.1834]    [Pg.24]    [Pg.436]    [Pg.130]   


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Pesticides mixtures

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