Comparison study of overlap among 21 scientific databases in searching pesticide information

The online search activities described here were conducted to provide environmental scientists with literature to use in their review of pesticide chemicals for regulatory decisions. The first criterion for this data gathering process was to have complete coverage to approach 100% recall of the papers published on the pesticide in question. As new databases were developed and current ones were updated, the number of searchable files multiplied. Running large profiles against each data‐base now resulted in, increased online costs, (connect‐time/print charges), greater overlap and duplication and, inundating the reviewer with thousands of citations. Thus it became apparent that the effectiveness of searching this multitude of applicable databases must be evaluated. Where is the overlap? Which data‐bases contain unique citations? How can the number of databases be decreased without minimizing the percentage of coverage?