This report about the effects of pesticides on the human immune system makes one thing abundantly clear: we need to know more about these linkages, but we already know more than enough to take preventive action.

Hundreds of millions of farmworkers, farm households, and consumers are probably exposed to dangerous levels of pesticides. Most of these people live in the developing world and the countries of the former Soviet Union. In many cases, they are using chemicals with known acute and chronic toxicity and applying them without adequate safeguards.

The scientific evidence suggesting that many pesticides damage the immune system is impressive. Animal studies have found that pesticides alter the immune system\'s normal structure, disturb immune responses, and reduce animals\' resistance to antigens and infectious agents. There is convincing direct and indirect evidence that these findings carry over to human populations exposed to pesticides.

Even a conservative guess about the years of productive life that are being lost around the world as a result of this problem would suggest that a small investment to minimize the risks will almost certainly provide benefits that far outweigh the costs.

Pesticides and the Immune System: The public health risks continues an effort that dates back over many years at WRI to examine the health effects of environmental pollution and policies that will move us towards more sustainable agricultural practices. In Field Duty: U.S. farmworkers and pesticide safety, Robert Wasserstrom and Richard Wiles assessed both the scientific and policy issues surrounding pesticide use and farmworker safety. In A Better Mousetrap: Improving pest management for agriculture, Michael J. Dover examined the strategies embodied in Integrated Pest Management that could reduce the health risks associated with pesticides. Paying the Price: Pesticide subsidies in developing countries, by Robert Repetto, described how government subsidies for pesticides in developing countries encouraged wasteful use and needlessly increased health risks. More recently, Paul Faeth\'s Growing Green: Enhancing the economic and environmental performance of U.S. agriculture systematically examined the economic and environmental effects on changes in U.S. farm policy.

This study typifies WRI\'s team approach to research. The WRI team included Robert Repetto, WRI vice president and a former professor at the Harvard School of Public Health, and Sanjay Baliga, who graduated from Stanford University and acquired an M.P.H. degree at the University of Michigan. The team was aided by an advisory panel with extensive experience in this field.

Pesticide-induced immunosuppression is one of several emerging, imperfectly understood health risks associated with chemical exposures. The evidence assembled in this report underscores the need to continue improving our understanding of such risks.

For our part, WRI plans to aggressively expand its work in this area in the coming years. In 1995 we began a new program on health, environment, and development headed by Dr. Devra Davis. This program is intended to fully inform policy-makers about the environmental determinants of threats to public health and about the opportunities to reduce the risks of disease through sound environmental stewardship.