Drafts of Unofficial Report Looking at Great Lakes Pollution, Health Data, Have Limited Scientific Quality

Published on Sep 5, 2008 - 9:14:06 AM

By: The National Academies

WASHINGTON, Sept. 5, 2008 - Two drafts of a yet-to-be-finalized report looking at health and pollution data from the Great Lakes region have problems that diminish the documents' scientific quality, says a review by the Institute of Medicine (IOM). These shortcomings limit the usefulness of the drafts - prepared by the U.S. Centers for Disease Control and Prevention - in determining whether health risks might be associated with living near the lakes.

Questions about the scientific quality of the drafts and concern following the unauthorized publication of one of the interim drafts on a public Web site led CDC to ask the IOM for an independent review of the documents. The drafts originated with an international commission's request for CDC's Agency for Toxic Substances and Disease Registry (ATSDR) to evaluate the public health implications of hazardous materials present in certain areas within U.S. states in the Great Lakes basin. The IOM committee focused on a 2007 draft and a 2008 version that was prepared after directors within ATSDR expressed apprehension about the 2007 draft's methodology and conclusions and postponed its public release. No final report has been released.

"We found problems in how each draft was developed, which data were used, and what conclusions the authors drew," said Robert Wallace, Irene Ensminger Stecher Professor of Epidemiology and Internal Medicine, College of Public Health, University of Iowa, Iowa City, and chair of the committee that wrote the report. "Our task was to focus solely on the scientific quality of the drafts and not to assess whether pollution around the Great Lakes poses health concerns," he added. "The problems we found in the drafts would limit the ability of officials and others to draw conclusions from them about whether any health risks are associated with living in or near certain places around the Great Lakes."

Most of the concerns about the 2007 draft raised by CDC's peer reviewers and ATSDR directors - particularly how data were selected and used - are valid, the committee concluded. Pollution and health data were lumped together despite differences in where and when the information was collected and despite lack of supporting evidence or explanation of how particular contaminants could lead to any of the identified health problems, the report says. This juxtaposition of data without explanation or support could lead readers to assume links between contamination and health problems regardless of whether they actually exist. Furthermore, some data that might have provided useful evidence apparently were not considered, and the drafts contained little explanation for why the data used were chosen.

The 2008 draft provides only a summary of selected data on chemical releases and contamination and does not add substantially to the understanding of pollution around the Great Lakes, the committee concluded. Though the authors' decision to leave out the health data in the 2008 draft is understandable given its incompatibilities with the available contamination data, it significantly changed the nature of the resulting draft and scope of response to the original request to CDC. The committee also noted problems with using the selected contaminant data as indicators of actual exposures. Moreover, the draft lacks information on other potential sources of contaminants or ways that people could be exposed.

Many of the drafts' problems seem to stem from lack of a clear statement about what each draft was intended to achieve and a clear outline of its approach. The IOM committee noted that the original request for a study could have been interpreted in more than one way; neither draft offered an explanation of how the request was interpreted.

The study was sponsored by the U.S. Centers for Disease Control and Prevention. Established in 1970 under the charter of the National Academy of Sciences, the Institute of Medicine provides independent, objective, evidence-based advice to policymakers, health professionals, the private sector, and the public. The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies.

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