Pesticide losses, environmental factors

Figure 7.1 Environmental factors leading to pesticide losses...

Data on exposure and environmental fate are needed, not to determine toxicity, but to provide information that may be useful in the prediction of possible exposure in the event that the chemical is toxic. These tests are primarily useful for chemicals released into the environment such as pesticides, and they include the rate of breakdown under aerobic and anaerobic conditions in soils of various types, the rates of leaching into surface water from soils of various types, and the rate of movement toward groundwater. The effects of physical factors on degradation through photolysis and hydrolysis studies and the identification of the product formed can indicate the rate of loss of the hazardous chemical or the possible formation of hazardous degradation products. Tests for accumulation in plants and animals and movement within the ecosystem are considered in Section 21.7. 

Upon release the formulated control agent is partitioned between the air, the forest vegetation and the forest floor. It is the post application loss of insecticides from conifers which is the subject of the following discussion. Volatilization has become increasingly recognized as a significant factor which limits the efficiency of pesticides and provides a major pathway to general environmental contamination. 

We have tried to emphasize not only the importance of the problem of the availability, but also that of the precise specifications of C, S, (etc.) labelled compounds, namely the specificity of the labelling position and the radiochemical purity. These two parameters are of vital importance for the future application of the labelled molecule in medicine, biology and the environmental sciences. Furthermore, two factors must be considered for the reliability of metabolic studies of drugs and pesticides correct choice of labelling position, since a position that is too exposed can result in loss of the label and consequently incomplete results the other factor is that of stable isotopes and the so-called isotopic effect. 

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