LETTERS: EPA CONVINCED PCBs ARE HAZARDOUS

To the editor:

In response to growing concerns over health and environmental risks posed by hazardous waste, Congress enacted federal laws to deal with the dangers posed by hazardous-waste sites. Congress gave the Environmental Protection Agency the task of protecting this country's people and the environment and returning our lands to productive use.

EPA has the important role of providing full and accurate information about the risks of pollutants such as polychlorinated biphenyls, or PCBs. The scientific evidence support the conclusion that PCBs probably cause cancer in people. The scientific evidence also shows that PCBs post serious health threats and may pose special risks to children.

Human and animal studies strongly suggest that PCBs probably cause cancer. In 1996, at Congress' request, EPA completed an extensive reassessment of PCBs and cancer. The reassessment reflects EPA's commitment to using the best scientific information and risk-assessment methods in its decision making. EPA reviewed more than 20 studies concerning PCBs' effect on people and animals. All the studies supported the finding that PCBs cause cancer.

EPA is not alone in its concern about PCBs. The International Agency for Research on Cancer has declared PCBs to be a probable human carcinogen. In addition, the National Institute for Occupational Safety and Health has determined that PCBs are a potential occupational carcinogen. The Food and Drug Administration specified PCB concentration limits in baby foods, eggs, milk fat and poultry fat.

Animal experiments have shown that some PCB mixtures produce adverse health effects including liver damage, skin irritations, reproductive and developmental effects and cancer. Therefore, it is very important to consider that there may be health hazards for people.

Studies on people and animals have demonstrated reproductive and developmental effects from PCB exposure. These studies suggest that children may be the most susceptible to PCB exposure.

Two studies in the Netherlands and one study in Japan have shown a connection between increasing PCB exposure and decreasing thyroid hormone concentrations in babies. EPA and the National Academy of Sciences are currently reviewing the available scientific studies to determine whether a strong link with human effects can be established.

EPA is concerned about potential nervous-system and analytical effects in children who have been exposed to PCBs. Monkeys exposed to PCB levels in human milk developed long-term learning disabilities. EPA and other federal agencies are supporting research to better understand these potential effects.

People's immune systems may be impacted following exposure to PCBs. Animal studies have shown that PCBs suppress the immune system. PCB exposure in these animals made them more prone to viral infections that are often fatal.

PCBs also have been shown to cause long-term reproductive problems. Female monkeys exposed to various PCBs showed lower reproductive performance, including spontaneous abortions and reduced birth weights. Adverse reproductive effects continued long after exposure ended and through several generations, suggesting that PCBs can have a lasting effect. The evidence for reproductive effects in animals reinforces concerns of the potential reproductive toxicity of PCBs in people.

Based on all the current available evidence, EPA is convinced that PCB contamination at the Missouri Electric Works site poses a significant threat to public health and the environment. EPA is committed to fulfilling its statutory mandate to protect human health and the environment.

MICHAEL J. SANDERSON, Director

Superfund Division, Region VII

Environmental Protection Agency

Kansas City, Kan.