useful for double-checking the thoroughness of the primary search strategies. In addition, the primary and secondary searches combined yielded many pertinent case reports, background, and review articles that were retained for use as supporting material as needed by the committee.

To ensure that the committee reviewed the complete body of evidence before forming its conclusions, searches were conducted through August 2001.

Other Sources

Identifying the pertinent literature was a continuing process throughout the study. In addition to the formal online searches, the committee and staff examined the reference lists of major epidemiologic studies, review articles, and textbooks for relevant citations. The bibliographies of such reports as the International Agency for Research on Cancer’s monograph series, ATSDR’s Toxicological Profiles, the World Health Organization’s Environmental Health Criteria documents, and the technical reports of the European Centre for Ecotoxicology and Toxicology of Chemicals provided many relevant citations. Online library catalogs, including those of the US National Library of Medicine and the National Institutes of Health, were searched for textbooks and other monographs that could provide pertinent overview and background materials for the study.


The results of the online searches and citations identified by other means were imported into ProCite, a software program designed to store and manage bibliographic data. When the search phase was completed, ProCite contained nearly 30,000 citations that included all the relevant and nonrelevant epidemiologic and toxicologic studies, background reports, and other articles. Staff reviewed each citation carefully and identified about 3000 citations as most relevant to the committee’s charge. The citations selected were studies of human populations exposed to the agents of interest that examined the potential for adverse health effects. The full text of those journal articles was retrieved and sent to committee members for their review.

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