Learning Disabilities Association-Sponsored Symposium on Chemical Hormone Impostors and Child Development
Heindel, Jerry, Environmental Health Perspectives
The Learning Disabilities Association (LDA) is a parent-run, all-volunteer organization started in 1960. It now numbers 50,000 members with affiliates in every state. The association is self-supported and undertakes advocacy initiatives in the areas of prevention, services, education, and research concerning learning and overlapping developmental disabilities. Originally, the total focus was remediation of specific academic learning disabilities, such as dyslexia, that were evident in the classroom. Over time, attention has broadened with the realization that behavior, social perception, functional coordination, etc. must be considered in the context of whole-person development. The LDA is especially interested in the areas of early assessment and intervention, behavior, social perception, and functional coordination as they pertain to outreach and education. The national LDA maintains 20 committees to cover the multifaceted concerns of members. The committees interact with a myriad of professional and lay sources of information to provide constructive directions and initiatives.
One of the LDA standing committees is the Research Services Committee. A current initiative of this committee is directed at the urgent challenge presented by the recognition that environmental chemicals may be altering hormones, especially those necessary for normal fetal development, and thus contributing to the perceived increase in developmental disabilities. In an effort to address the possible relationship of exposure to endocrine-disrupting chemicals and learning disabilities, the LDA sponsored a symposium, titled "Chemical Hormone Impostors and Child Development: Learning, Behavior and Function," at the LDA International Conference in Atlanta, Georgia, 24-25 February 1999. The Jennifer Altman Foundation, The National Institute of Environmental Health Sciences (NIEHS), The Agency for Toxic Substances and Disease Registry (ATSDR), The Physicians for Social Responsibility, and the U.S. Environmental Protection Agency (EPA) jointly sponsored the symposium.
There is growing evidence that hormonally active chemicals accumulating in the environment worldwide may adversely affect humans and wildlife. There is also evidence that alterations in thyroid hormone levels can compromise brain development from conception on, resulting in learning and functional decrements. Thus the goals of the symposium were to explore the available research data, identify research and policy gaps, identify steps to reduce exposures and motivate public awareness, and to define future directions. The symposium was attended by more than 100 scientists, teachers, and lay persons interested in learning about the current state of knowledge relating exposure to hormonally active compounds, particularly polychlorinated biphenyls (PCBs) and pesticides, with the resulting alterations in brain development, thyroid hormone status, and learning disabilities.
Seven lectures were presented at the symposium. The symposium began with an overview of the data linking exposure to endocrine-active chemicals to human health. Currently the best approach to this problem is to use weight of evidence in determining a possible role of hormonally active compounds; it is difficult to show cause-and-effect relationships between exposure and human disease. Recent laboratory, epidemio-logic, and wildlife biologists' studies conducted in the Great Lakes Basin and elsewhere provide a strong weight of evidence for the hypothesis that some environmental chemicals may act as thyroid hormone disruptors. It was proposed that a research program in this area should use a framework of surveillance of populations at risk and an evaluation of the human and animal data, including exposure information. This information could then be used in prevention, risk communication, and education programs.
The next presentation discussed the role of thyroid hormones in development and the possibility that PCBs might exert their toxicity via alterations of thyroid hormone function during development. …