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registration (it costs $40 - $80 million to bring a new pesticide to the market). Too great a
selectivity may also involve costs to the user because mix tures of several compounds may have
to be used to control all pests present in a certain situation. This not only involves greater use of
pesticides but may require more frequent use of spray and a pplication equipment. 3.2 TOXICITY TESTING FOR ENVIRONMENTAL TOXICOLOGY Standardized test methods are routinely used and required by a number of regulatory agencies.
In Canada, several standardized test methods have been suggested by Environment Canada at the
federal level and, at the provincial level, test methods have been developed for use in the
Municipal and Industrial Strategy for Abatement (MISA) as regulated by the Ontario Ministry of
the Environment. In the U.S., a number of test methods have been developed by the U.S. EPA
(CFR 2004) and others such as Environment Canada. The Organization for Economic
Cooperation and Development (OECD) has published a number of methods (OECD 1981, 1984)
and American Society for Testing and Materials (ASTM) has a long history of methods
development, testing and validation ( ASTM 1991). Guidance for
interpreting tests and for analyzing data is also available
(Environment Canada 1999b).
stomate Through the
roots (soil) Figure 3-151
Routes of exposure for plants. 3.2.4
Terrestrial systems, plants
Plant toxicity tests are legion and largely non -standardized,
although an attempt has been made to develop a standardized
testing system in Canada (Boutin et al. 1993) and an update of this
procedure has recently been presented to the USEPA
(Davy et al. 2001) for review but has not yet been adopted.
Environment Canada has published test methods for plan ts
(Environment Canada 2005). Routes of exposure in terrestrial plants include air, soil and water ( Figure 3-15). Aerial
exposure includes volatile substances which enter through stomates as well as particulates and
liquids which enter t hrough the leaf surface. Measures of effect include growth of shoots, roots
and the entire plant as well as reproductive potential as in seed production. More often than not,
scoring systems are used or the measurement endpoint is compared to that in con trol untreated
plants. Measures of effect are usually not quantal but may be subjected to any suitable transform
for the purposes of interpolation. Extrapolation beyond the data range is not recommended for
3.2.2 Terrestrial Systems: Invertebrates
The only assay on a terrestrial invertebrate that is required for regulatory risk assessment in the
USA is the bioassay of the honey bee and its sensitivity to pesticides ( Urban and Cook 1986).
However, a wide range of insects are routinely tested for sensitivity to pesticides in regard to
integrated pest management (IPM) and resistance monitoring programs. Earthworms and other
soil invertebrates are tested in Europe and have been proposed by the OECD as terrest...
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