Chemicals in the workplace: incorporating human neurobehavioral testing into the regulatory process

In February 1996, the United Kingdom Health and Safety Executive sponsored a workshop on the role of human neurobehavioral tests in the regulation of chemical exposures in the workplace. This paper presents the review of neurobehavioral testing that was initially prepared for the workshop but has been expanded and updated for publication. Information sources for the review were drawn from "preamble to the regulation," in the 1989 air contaminants project, an attempt by the Occupational Safety and Health Administration to update the 1968 regulatory limits of workplace exposures. The scientific citations listed in the preamble provide a chemical database to review for evidence of neurobehavioral testing to support limit setting. Several conclusions emerged: 1) A wide range of nervous system effects were reported in the scientific citations for the 172 chemicals identified with effects on the nervous system; 2) Citations of studies with human neurobehavioral test results are used to support limit setting, but many are old studies primarily of acute effects; 3) There is frequently a delay of several years after publication before studies with neurobehavioral testing are cited in regulatory forums; 4) With the 1989 proposed regulatory limits never legally adopted, there has not been an update for most of the substances affecting the nervous system since 1971; 5) Investigators should be more aware of the regulatory process and submit studies reporting neurobehavioral test results to organizations that regulate and recommend workplace exposure limits; 6) Issuances in the Federal Register by the U.S. Environmental Protection Agency provide a framework for assessing neurotoxic risks that can be used by investigators to help identify and report nervous system effects using neurobehavioral testing in a more uniform fashion.