Over the past 50 years, society has adopted a way of life heavily dependent on chemicals. The first evidence of injury by persistent toxic substances also was reported more than 50 years ago. Concern focused on fish and wildlife -- decreased hatching success, metabolic abnormalities, gross birth defects and cancer. As the body of evidence increased, the use of the most insidious persistent toxic substances -- such as DDT and PCBs -- was severely restricted or banned, and initiatives were undertaken to control releases to the environment and to clean up contamination. As a result, contaminant releases decreased significantly and exposure declined.
The Great Lakes environment has improved dramatically over the past quarter century. The biotic community rebounded with increased hatching success among herring gulls, decreased incidence of deformities and return of viable bald eagle populations along the Great Lakes shorelines. Most recently, four species of fish -- young sturgeon, lake trout, lake herring and deep-water sculpin -- have reappeared in Lake Ontario after absences of up to several decades. These successes are positive signs that the lakes are returning to better health. They clearly reflect the effectiveness of legislation, regulations and programs undertaken in both countries, driven largely by increasing public concern about the health and welfare of the environment and by the courage and willingness of governments to deal with Great Lakes environmental problems.
While these improvements were being recorded, evidence continued to build of subtle, more insidious injury, especially neurobehavioural injury resulting from endocrine disruption during fetal development. In addition to substances already identified, others also may cause injury. Among chemicals widely distributed in our environment and reported to have endocrine-disrupting effects are pesticides such as atrazine, alachlor and methoxychlor as well as industrial chemicals such as phthalates, which are used as plasticizers.4 Among the effects of endocrine-disrupting chemicals on fish and wildlife are behavioural abnormality, compromised immune system and sex change. Recognizing this concern, the Commission in its Sixth Biennial Report recommended a weight-of-evidence approach to identify persistent toxic substances.
Thus, despite improvements, society has not yet gone far enough. Contaminant body-burdens remain a concern -- injury is still occurring. Some believe that actions taken to date are sufficient and that, in time, the ecosystem will respond and contaminant concentrations will decrease further, notwithstanding an equilibrium period approaching two decades. Others contend that the system has established an equilibrium, that levels will not appreciably decrease, that society cannot afford to wait and that additional action is required.5
Most disturbing is increasing evidence that persistent toxic substances also injure human beings.6 The first warning signals of human injury by chemicals at levels present in the ambient environment were raised more than a decade ago, when results were published on a study of women who consumed Lake Michigan fish prior to giving birth. As a result of prenatal exposure to PCBs, the infants of these mothers had lower weight and smaller head circumference at birth, as well as a shorter gestational age and poorer neuromuscular development. As they grew, other injury was identified and reported, primarily related to memory, IQ, attention, and learning and behavioural problems. Other studies continue to provide corroborating evidence of injury to humans in the form of subtle functional deficits. The studies have been published in peer-reviewed literature, and those sponsored by the Agency for Toxic Substances and Disease Registry7 and by Health Canada have been the subject of intense Commission consideration, in terms of understanding the nature and the extent of injury as well as investigating the policy implications of that injury.
The evidence is overwhelming: certain persistent toxic substances impair human intellectual capacity, change behaviour, damage the immune system and compromise reproductive capacity. The people most at risk are children, pregnant women, women of childbearing age and people who rely on fish and wildlife as a major part of their diet. Particularly at risk are developing embryos and nursing infants. Injury has occurred in the past, is occurring today and, unless society acts now to further reduce the concentration of persistent toxic substances in the environment, injury will continue in the future. The fact that such injury is occurring, coupled with a lack of knowledge about other, as yet unrecognized, effects is a call for action by all basin stakeholders to minimize and eliminate injury.
The destination of the journey is the achievement of the Agreement's purpose: "to restore and maintain the chemical, physical, and biological integrity of the waters of the Great Lakes Basin Ecosystem." The public have put it more succinctly and clearly -- they want clean lakes, without persistent toxic substances.
To track progress toward this goal and determine when it has been achieved, the Commission over the past few years has characterized the Agreement's purpose in more quantifiable terms, building on the concepts of virtual elimination of inputs and zero discharge, as well as the beneficial use impairments in the Agreement. The Commission, through its Indicators for Evaluation Task Force, identified nine positive desired outcomes8 and proposed specific indicators and measurements to quantify each.
Characterization of the Agreement's Purpose
The driving force behind the Agreement was the continuing concern of the Parties "about the impairment of water quality on each side of the boundary to an extent that is causing injury to health and property on the other side"(Preamble). Although governments -- indeed society -- are striving to achieve the Agreement's purpose, two questions can be asked:
The Agreement states that "it is the policy of the Parties that . . . the discharge of toxic substances in toxic amounts be prohibited and the discharge of any or all persistent toxic substances be virtually eliminated" (Article II). "The intent . . . is to virtually eliminate the input of persistent toxic substances in order to protect human health and to ensure the continued health and productivity of living aquatic resources and human use thereof" and "the philosophy adopted for control of inputs of persistent toxic substances shall be zero discharge" (Annex 12).
In its Sixth Biennial Report, the Commission concluded "that persistent toxic substances are too dangerous to the biosphere and to humans to permit their release in any quantity." Given the impediments to total elimination of persistent toxic substances from the Great Lakes system, virtual elimination of inputs is a more realistic objective. The Commission was quite emphatic that "zero discharge means just that: halting all inputs from all human sources and pathways and to prevent any opportunity for persistent toxic substances to enter the environment as a result of human activity."
In its Seventh Biennial Report, the Commission adopted the report of its Virtual Elimination Task Force, A Strategy for Virtual Elimination of Persistent Toxic Substances, and commended it to governments as a framework for action. The task force's vision for the virtual elimination strategy is "ecosystem integrity, characterized by a clean and healthy Great Lakes Basin Ecosystem and by the absence of injury to living organisms and to society."
The nine desired outcomes developed by the Commission's Indicators for Evaluation Task Force articulate the Agreement's purpose in more quantitative terms. To quantify each, the task force also proposed specific indicators and measurements. Quantitative data and information developed for explicitly stated desired outcomes provide the basis to gauge progress toward the Agreement's purpose and to hold governments accountable for its achievement.