acute in an area that has been changing rapidly, like environmental regulation. Furthermore, environmental policy is an indirect activity: it seeks to influence human behavior with the ultimate goal of changing environmental conditions. Because the environment responds to laws of nature and not to laws made by people, it has proven difficult to achieve satisfactory results through legal analysis alone.

A two-tiered implementation gap exists: laws are not adequately enforced, and even adequately enforced laws do not change environmental conditions sufficiently. As a result, environmental policy has proceeded in cycles as it has become increasingly clear that certain measures or standards do not achieve the desired result. This has inevitably increased the complexity of the policy structure. It is now manifest that single measures of environmental performance do not exist: measurement is necessary along the entire pathway of pollutants to ensure that the ultimate goal—environmental quality—is actually achieved, and policy must follow actual environmental conditions. An OECD study of the early eighties put it succinctly: ''… in practice, there is no single control procedure which can provide a safe barrier to the spread of pollutants, and thus safe environmental protection."⁹

Legislation is needed until satisfactory environmental conditions are attained, and that can frequently require many iterations of the legislative process. Exclusive focus on legislation does not capture the actual nature of environmental management. It can, however, provide useful insights concerning possible regulatory tools to employ.

In the search for more readily comparable aspects of environmental management, attention has turned to "standards." Generally expressed in technical terms, standards appear to offer a comparable basis for evaluating environmental policies in different countries. However, two difficulties exist in comparing standard: variations in the definition of standards and in their application in practice.

Several distinct types of standards exist.¹⁰ It is common to distinguish among product standards, process standards, and environmental quality standards, but in practice further variations exist, including emission standards, exposure standards, and biological standards. Figure 1 provides a schematic overview of the possible points on the pollutant pathway at which standards or objectives may be set.

Attempts to "harmonize" standards internationally have proven difficult. The experience of the European Community (which has undertaken more extensive international harmonization of environmental standards than any other organization) is instructive. It indicates how apparently simple issues such as determining blood lead levels in humans, harmonizing water quality management or defining product standards for automobiles can lead to major complications.¹¹

The EC has experienced what can only be described as competitive standard-setting,