Surfactant Effects on Environmental Behavior of Pesticides - Reviews of Environmental Contamination and Toxicology - page 156

through the preparation of formulations, but fundamental profiles, especially for a
specific monodisperse surfactant, are not fully studied. Reduced volatilization of a
pesticide from the formulation can be explained by analogy of a very simple
organic chemical, but the actual mechanism for the pesticide is still obscure. In
contrast, from the point of view of avoiding groundwater contamination with a
pesticide, adsorption/desorption profiles in the presence of surfactants and adju-
vants have been examined extensively as well as pesticide mobility in the soil col-
umn. The basic mechanism in micelle-catalyzed hydrolysis is well known, and
theoretical approaches including the PPIE model have succeeded in explaining the
observed effects of surfactants, but its application to pesticides is also limited.
Photolysis, especially in an aqueous phase, is in the same situation. The dilution
effect in the real environment would show these effects on hydrolysis and photoly-
sis to be much less than expected from the laboratory basic studies, but more infor-
mation is necessary to examine the practical extent of the effects in an early stage
of applying a pesticide formulation to crops and soil. Many adjuvants, including
surfactants, are biodegradable in the soil environment, and thus their effects on the
biodegradation of a pesticide in soil and sediment may be limited, as demonstrated
by field trials. Not only from the theoretical but also the practical aspect, the foliar
uptake of pesticide in the presence of adjuvants has been investigated extensively
and some prediction on the ease of foliar uptake can be realized in relation to the
formulation technology. However, effect on root uptake of pesticides is to be further
investigated. In an aqueous environment more or less contaminated by various
chemicals such as detergents and their degradates, it is necessary to investigate the
effect of adjuvants on uptake, bioconcentration, and trophic transfer of pesticides
for better understanding of pesticide contamination of aquatic species in the aquatic
environment.
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