Pesticide Degradation in Water - Pesticides: Evaluation of Environmental Pollution - page 92

H 3 CO

OCH 3

OCH 3

H 3 CO

N N

N N

O

O

H

COOH

CO 2 Pr

M2

ZJ0273

FIGURE 4.6
Herbicide ZJ0273 and its main metabolite M2.

underestimated if bound residues may be released from soil. For example, a study on
the phytotoxicity of soil-bound residues of the herbicide ZJ0273, a novel acetolactate syn-
thase potential inhibitor, to rice and corn, revealed that one of its main metabolite (M2)
(Figure 4.6) played a dominant role in the inhibition effect on the growth of rice seed-
lings. In the extractable residues released from bound residues, the most biologically
active M2 accounted for the largest fraction in all soils. Therefore, it was concluded that
the main cause of phytotoxicity from exposure to soil-bound residues of ZJ0273 is related
to the release of ZJ0273 and its degradation products and the subsequent inhibition of
acetolactate synthase (ALS) by M2 (Han et al. 2009).

4.4 Legislative Framework of Pesticide Residues in Water
In the scope of legislation about pesticide residues in water, it is necessary to differenti-
ate between groundwater and surface water. Generally, there is less information on the
presence of pesticides in groundwater than in surface water. In addition, in contrast to
food analysis, where there is more precise and extensive legislation about the definition
of residues and maximum acceptable residue levels, the regulation of residues in water
is still poor with respect to the definition of residues and only gives general reference
to pesticide-related compounds. Although it is worth mentioning that the legislation
has evolved during the last few years to increasingly consider metabolites and degra-
dation products as part of pesticide residues to be considered for risk assessment and
monitoring.

4.4.1 European Union Water Legislation

In 2002, in the European Union (EU), the Water Framework Directive (WFD) (European
Commission 2000) established a new legislative approach to manage and protect water by
the coordination of different EU policies, based on geographical and hydrological forma-
tions (river basins), and made it the responsibility of Member States to draw up river basin
management plans. The WFD takes account of all aspects of water use and consumption.
The objective is that all European waters have to achieve “good ecological and chemical
status” to protect human health, water supply, natural ecosystems, and biodiversity. The