companies, the Social Security Administration, and the Department of Veterans Affairs might have information useful for a specific surveillance project, but most fall short by not having both health and occupational data (data on actual exposures are almost never found), by being drawn from an inadequately defined population, by having restricted availability, or by being limited to a period that is not of interest.

The National Research Council Panel on Occupational and Health Statistics (NRC, 1987a), after reviewing the various sources of information on adverse health events, concluded that the information available on occupational injuries is poor and that the information on occupational illnesses is considerably worse. Those data sources were not designed to determine the causes of disease, nor do they emphasize occupational or environmental exposures. Thus, the contribution of such exposures to the etiology of a given disease is not usually recognized (ASPH, 1988). The end points selected for surveillance are usually restricted to overt clinical disease or death.

Once cases are reported, officials can collect further information and provide appropriate followup and suggestions for prevention in the workplace. The reporting systems must be interactive and provide a means for followup of reported cases to ensure continued physician involvement in the surveillance program. State and local health departments, in collaboration with occupational clinic groups, probably provide the best basis for such reporting systems.

When an excess or cluster of a particular symptom associated with neurotoxicity (National Conference on Clustering of Health Events [1990]) or a new syndrome with involvement of the nervous system is detected, determination of the likely causes is the next stage of the epidemiologic process. It requires careful comparison between observed physical and temporal patterns of exposures to possible toxicants and the occurrence of the cases.

The NIOSH Health Hazard Evaluation Program and similar activities of academic or government groups provide mechanisms for rapid evaluation of reported outbreaks and can therefore confirm initial reports of a possible neurotoxic problem. California has pioneered the development of a reporting system for outbreaks of pesticide poisoning in which collaborating health and agricultural departments can intervene. However, similar systems for the reporting of such diseases by physicians are not well established elsewhere in the United States (ASPH, 1988).

The committee has considered several ideas for improving disease surveillance systems:

• Training of medical professionals. Many medical professionals who are in direct contact with persons with neurotoxic disorders of environmental origin lack the knowledge necessary to recognize these ailments or to identify their etiology. The ability to diagnose the disorders and to associate them with workplace or community exposures must be improved (U.S. House of Representatives, 1986). Physicians need to be made more aware that environmental exposures can produce toxic effects and should be trained to obtain an account of exposures received occupationally, avocationally, etc., as well as medically, when taking a history (Goldman and Peters, 1981). Better initial training in occupational and environmental medicine and the dissemination of more current information on neurotoxic illnesses would benefit both health practitioners and their patients (NRC, 1987a). The development of improved diagnostic tests and criteria would facilitate the recognition of an occurrence of neurotoxicity when it appears.

• Standardized disease definitions. Uniform clinical definitions of the disorders in question are needed to provide a common reporting basis for physicians. Such a nomenclature would also make the assembled

Front Matter (R1-R12)

Executive Summary (1-8)

1. Introduction: Defining the Problem of Neurotoxicity (9-20)

2. Biologic Basis of Neurotoxicity (21-42)

3. Biologic Markers in Neurotoxicology (43-52)

4. Testing for Neurotoxicity (53-94)

5. Surveillance to Prevent Neurotoxicity in Humans (95-110)

6. Risk Assessment (111-122)

7. Conclusions and Recommendations (123-128)

References (129-148)

Index (149-154)