Toward Chemical Integrity:
The Challenge of Contaminated Sediment and Human Health Impacts

Introduction

For people in the region, the Great Lakes have long been an abundant source of food, in the form of fish. In 1990, the International Joint Commission concluded there was a risk of injury from persistent toxic pollutants that had found their way through the ecosystem into the tissues of fish. Based on a growing volume of research, the Commission expressed particular concern about the effects of these substances on children who had been exposed in the womb, and as infants, to residues of toxic pollutants.

"When available data on fish, birds, reptiles and small mammals are considered along with this human research, the Commission must conclude that there is a threat to the health of our children emanating from our exposure to persistent toxic substances, even at very low ambient levels ... The mounting evidence cannot be denied. Governments must emphasize development and implementation of a comprehensive, binational program to lessen the use of, and human exposure to, persistent toxic substances found in the Great Lakes environment. These chemicals appear to be causing serious and fundamental physiological and other impacts on animal populations in the Great Lakes basin, and undoubtedly elsewhere. The dangers posed to the ecosystem, including humans, by the continuing use and release of persistent toxic contaminants are severe."¹

The Commission's 1990 conclusion, based on the earliest findings of harm to the health of children of mothers consuming large quantities of Lake Michigan fish, underscored the fact that scientific studies of the effects of persistent toxic substances on wildlife could predict effects on humans. Those studies had accumulated over the course of 30 years, and consistently showed that exposure to toxic substances in an ecosystem's food chain likely leads to adverse health effects in fish, reptiles, birds and mammals.

Studies continue. Today, a convincing body of scientific research clearly links human exposure to toxic substances in the Great Lakes to serious injury to health. These investigations include both epidemiological and experimental research studies, undertaken by Canada's former Great Lakes Health Effects Program and, in the U.S., by the Agency for Toxic Substances and Disease Registry.

• Table: Systemic Health Effects in At-risk Populations Exposed to Polychlorinated Biphenyls
• Table: Systemic Health Effects to Animals and Humans
  from Exposure to Persistent Toxic Substances

Other relevant findings from this decade of research include:

• numerous health effects observed in animals have been reported in humans
• concentrations of toxic polychlorinated biphenyls (PCBs), in the waters of all Great Lakes are approximately 100 times higher than the Great Lakes Initiative criteria for the protection of human health⁴
• the most significant known human exposure to toxins from the lakes comes from consuming contaminated Great Lakes fish
• the people at higher risk include sport and subsistence fish anglers, some ethnic populations, pregnant women, fetuses, nursing infants, young children, the elderly and the urban poor⁵
• there are effects on the reproductive function, such as conception rates and changes in the menstrual cycle
• maternal consumption of contaminated fish leads to exposure of the developing embryo and fetus and results in irreversible neuro-behavioral and developmental deficits after birth; consuming contaminated fish also affects neurological functioning
• over five million people eat Great Lakes sport fish.⁶ Among these are the high risk populations noted above.

In addition to injury to health, there are also economic and social impacts. The total economic cost to society for dealing with the health effects from exposure to contaminants has only begun to be estimated. At present, almost all of those costs are borne by individuals, families and non-federal institutions. Other costs include declining property values, and impacts on the tourism and recreation industries. Because navigational dredging can stir up or re-suspend contaminated sediment, economic harm can result in the form of added costs to, or restrictions on, the shipping industry. The inability to accurately estimate such costs under-represents the true harm to society from the continuing presence of contaminants and undermines the needed sense of urgency for action.

In short, we now know that injury is occurring. We believe that agencies' political leaders and managers are obligated to act decisively to protect their citizens from further injury.