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Environmental+Toxicology+Tox+2000+notes (2)

Earthworms and other soil invertebrates are tested in

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Unformatted text preview: rial test organisms for soils. Environment Canada ha s a test method for earthworms (Environment Canada 2004). Cuticular Oral Residual Respiratory Various routes of exposure include oral, dermal and respiratory ( Figure 3-16). The dermal route is often exploited in the use of treated surfaces. Death as an endpoint is relatively easily assessed in insects but reproductive effects may also be measured. As the responses are usually quantal, probit analysis can be used for statistical analysis. 3.2.3 Terrestrial systems, vertebrates Laboratory mammals and birds are most commonly used as surrogates for terrestrial wildlife (See Chapter 2, Section 2.6.2 and Chapter 4, Section Figure 32 4.2.1). In most cases, oral toxicity is measured, either Routes of uptake of toxic substances in terrestrial invertebrates as a dose or as a concentration in the diet. Most of the data for terrestrial vertebrates is generated in response to the regulatory requirements for pesticides. Long -term feeding studies for either chronic or lifetime exposures may also be undertaken. Experimentally, exposure is largely through the diet or by direct gavage but, in the environment, exposure may be through several routes, including dermal, respiratory and oral ( Figure 3-17). Exposure through drinking water (contaminated puddles) can also be tested. Exposure through preening in birds has been considered but is not routinely applied as a test method. Measures of effect such as death, reproduction, carcinogenicity, teratogenicity, neurotoxicity and physiological responses are usually considered. As the responses are usually quantal, probit analysis can be used for statistical analysis. Non quantal analysis may be applied to some measures of effect. Test methods for pesticides are published by the U.S. EPA (CFR 2004). 3.2.4 Aquatic systems, algae and macrophytes Tests on aquatic algae and aquatic macrophytes are Dermal commonly required for the registration of pesticides, Respiratory particularly herbicides. See reviews by Parrish (Parrish 1984) Lewis Oral (Lewis 1990) for general methods and interpretation of results. The use of Lemna spp as a representative aquatic macrophyte has been criticized Figure 3-173 as it is not rooted and does not Routes of exposure for terrestrial vertebrates produce seeds. It is, however, relatively easy to grow. Environment Canada has a test method for duckweed (Environment Canada 1999a). Routes of exposure are usually through the aquatic matrix. Measures of effect for algae are number of cells, chlorophyll content and carbon assimilation (photosynthesis). For macrophytes, number of fronds, internodal growth, chlorophyll c ontent and weight are common measures of effect. Statistical treatment is usually a non -quantal graphical analysis of percent of control response. 3.2.5 Aquatic systems, invertebrates Aquatic invertebrates are quite widely used because of the ease of production and because of their small size. These methods have been extensively described in the lit erature (Parrish 1984, Environment Canada 1990b, a, 1992...
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