Chemists are used to research and manufacture chemical and biological weapons. Chemists, under pressure from their employers, have adopted practices which lead to the underreporting of hazards of chemical pollution, failure to recommend adjustments toxicity thresholds in the light of potential hazards, and failure to investigate adequately the nature of such hazards. Examples include hazards of long-term exposure to low-level chemical pollutants in factories, and environmental consequences of uses of certain chemicals. In each case chemists have denied or suppressed evidence indicative of the levels of danger.