Criteria or guidelines? Dear Sir: In the recent feature article “Environmental Quality Criteria: What Type Should We Be Developing?’’ ( E S b T , Aug. 1991, p. 1352), Peter Chapman argues that the concept of rigid, enforceable environmental quality criteria is flawed, costly, and may not achieve the level of environmental protection for which they were originally designed. He then goes on to develop an alternative framework to eliminate these shortcomings. In this letter we point out a number of inaccuracies made with regards to Canadian activities in the field of environmental quality guidelines and criteria. In addition, we argue that such guidelines and criteria do have an important role in the Canadian framework for protection of the environment. We will conclude by noting that the alternative framework advocated by Chapman is vague and impractical in the real world. In Canada, the Canadian Council of Ministers of the Environment (CCME) is responsible for the development of environmental quality guidelines (not criteria as stated in the article). In North America, there is an abundance of terminology and definitions associated with guidelines and criteria. These terms are not interchangeable as suggested by Chapman but in fact have distinctly different definitions, derivation approaches, and guiding principles. For example, the CCME defines water quality guidelines as “numerical concentrations or narrative statements recomrnended to support and protect a designated water use” and water quality criteria as the scientific data evaluated to derive the guidelines. CCME guidelines are developed in a flexible framework that emphasizes professional judgment. Results of microcosms or field studies have been used to validate laboratory-to-field extrapolations or to derive the guideline value. Guidelines are designed to be a scientific best estimate of a safe limit that affords protection to water uses ( e g , aquatic life, irrigation water, etc.) during continuous exposure. In the United States water quality criteria are designed to protect most uses (e.g., 95% of aquatic biota) and have an acceptable frequency of exceedance.
Chapman’s inference that numerical criteria or guidelines are used as enforceable standards is inaccurate in the Canadian context. In Canada, it is recognized that guidelines are not a statement about the limit at which adverse effects will occur, but rather the limit at which effects could occur. As Chapman quite correctly points out, enforceable standards must take into consideration site-specific factors such as local environmental conditions, availability of technology, and socioeconomic costs. In Canada, these factors are taken into consideration in the development of site-specific objectives and standards. Canadian guidelines are not used as enforceable standards. Rather, the purpose of Canadian environmental quality guidelines is to streamline initial substance assessments and provide a consistent scientific foundation for the derivation of site-specific objectives and standards. In his article, Chapman makes several generic and specific recommendations for safeguarding environmental quality. They include: (1) measurement and assessment endpoints should be the same in order to avoid extrapolation errors from the former to the latter, (2) community and ecosystem-level measures of health should be derived, (3) stop wasting resources on low-priority issues such as oil spills and trendy chemicals and instead focus on high-priority issues such as climate change and stratospheric ozone depletion, and (4) develop a framework, not a number, to determine environmental quality. In evaluating these recommendations, we should keep in mind the major points made by Chapman in criticizing the environmental quality criteria approach: the recommendations must be biologically relevant, replicable, cost-effective, and ultimately safeguard the environment, Chapman’s first and second recommendations are essentially the same-if protection of ecosystem health is desired (the assessment endpoint) then community and ecosystem-level measures [the measurement endpoints) should be developed and used. In theory, implementation of this recommendation would ensure an accurate determination of ecosystem health simply because it is the most biologically relevant approach possible.
001 3-936X19210926-7$02.50/0 0 1991 American Chemical Society
In practice, however, t,he approach by itself fails on Several counts: (1) the results from most studies that have included measures of community and ecosystem health are highly variable and far exceed the variation between laboratory toxicity tests that Chapman found so objectionable, (2) once effects have been detected, the degradation may already be severe, and (3) site-specific studies of toxic chemical impacts on ecosystems become extremely costly when considered on a national or international scale. Nevertheless, if such information is available then it is used to validate and, if necessary, adjust Canadian environmental quality guidelines. With regards to the third recommendation, there is some truth to his contention of misplaced priorities, although it is interesting to note that stratospheric ozone depletion is due almost entirely to “trendy” chemicals such as chlorofluorocarbons and chlorinated solvents, and Kuwaiti oil spills may be contributing to global climate change (Le., a lot of little problems are usually required to create a big problem). Finally, Chapman’s recommendation to develop a framework, instead of a number, to determine environmental health is admirable except that he fails to develop such a framework and, as outlined above, “numbers” should and do play a major role in the framework used in Canada. In summary, we find it distressing that a leading Canadian environmental scientist is apparently so unfamiliar with the Canadian experience that he fails to accurately present key features of Canadian environmental quality guidelines in an E S b T feature article. D.R.J. Moore Commercial Chemicals Branch Environment Canada R. A. Kent, M. P. Wong, A. R. Davis Water Quality Branch Environment Canada Ottawa, Canada K I A OH3 This letter is the opinion of the authors and not necessarily that of Environment Canada.
Peter M . Chapman replies: I am pleased that Moore et al. have followed my suggestion and have published their comments on my recent feature article in ESbT. GenEnviron. Sci. Technol., Vol. 26, No. 1, 1992 7
