The risk evaluation supports EPA's conclusion that this section of the river may present an imminent and substantial endangerment to human health. Studies Conducted in Humans GE presents a misleading summary of the results of studies of PCB health effects in humans. This study did not examine cancer as an endpoint and its conclusions referred only to that limited study. EPA relies on the results of published, peer reviewed studies in determining the toxicity of environmental contaminants, and we consider the formulation of conclusions based on studies that have not been published or subject to peer review to be premature. Detailed, controlled studies in animals, including studies in monkeys, have demonstrated immunological, reproductive and neurological effects from PCB exposure.
Epidemiological studies raise concerns for potential noncancer health effects in humans.
We agree that the majority of epidemiological studies of PCBs have been inconclusive. However, these studies do not demonstrate that PCBs do not cause cancer or other serious health effects in humans. In the absence of conclusive data in humans, EPA has relied on the overwhelming evidence in animals that PCBs are probable human carcinogens and have a number of serious potential noncancer health effects. Endocrine disruption is a rapidly developing research area which is of significant potential concern to the Agency. While data on PCBs are still limited, there has been significant discussion about the potential for PCBs to cause endocrine effects.