Methods for Deriving Pesticide Aquatic Life Criteria - Reviews of Environmental Contamination and Toxicology - page 32

did not meet the needs of California regulators, Lillebo et al. (1988) developed a
criteria derivation methodology, specifically for use in California, designed to
ensure full protection of aquatic biological resources. In Australia and New
Zealand, the goal is “to maintain and enhance the 'ecological integrity' of freshwater
and marine ecosystems, including biological diversity, relative abundance and ecological
processes” (ANZECC and ARMCANZ 2000). German quality targets are designed
to “maintain or restore a self-reproducing and self-regulating biocenosis of plants,
animals, and microorganisms that is typical of the location concerned and is as
natural as possible” (Irmer et al. 1995). The OECD guidelines provide methods for
derivation of criteria “where no adverse effects on the aquatic ecosystem are
expected” (OECD 1995). Denmark derives water quality criteria that are defined as
ecotoxicological no-effect concentrations (Samsoe-Petersen and Pedersen 1995).
The PNECs derived by the EU risk assessment methodology (ECB 2003), are
intended to ensure “overall environmental protection,” whereas, the Scientific Advisory
Committee on Toxicity and Ecotoxicity of Chemicals/European Economic Comm-
unity (CSTE/EEC) states that WQOs should permit all stages in the life of aquatic
organisms to be successfully completed, should not produce conditions that cause
organisms to avoid habitat where they would normally be present, should not result
in bioaccumulation, and should not alter ecosystem function (Bro-Rasmussen et al.
1994; originally in CSTE/EEC 1987). The state of North Carolina seeks to ensure
aquatic life propagation and maintenance of biological integrity (North Carolina
Department of Environment and Natural Resources 2003). As discussed previously,
the mandate of the Central Valley RWQCB is to maintain waters free of “toxic
substances at concentrations that produce detrimental physiological responses in
human, plant, animal, or aquatic life” (CVRWQCB 2004).

5.2 Portion of Species to Protect

Despite somewhat differing goals, all methodologies are forced to rely a great
deal on single-species toxicity data to derive criteria. As pointed out in ECB
(2003), two important assumptions are critical to these methodologies, which
seek ecosystem protection by extrapolation from single-species laboratory eco-
toxicity tests: (1) ecosystem sensitivity depends on the most sensitive species;
and (2) protecting ecosystem structure protects community function. This
approach is common throughout the world and results from the relative availa-
bility of data from single-species toxicity tests, compared to multispecies or
ecosystem data.
A corollary assumption is that ecosystems can sustain some level of damage
(e.g., to individuals or populations) from toxicants or other stressors, and subse-
quently recover with no lasting harm. This assumption is not completely supported
in the literature. As discussed by Spromberg and Birge (2005a, b), whether or not
population-level effect results from toxicity-induced physiological responses of
individuals depends very much on life-history characteristics of the particular species.