ABSTRACT
Agents may be either biological (pathogens or toxins) or chemical. Contact can potentially produce both local and systemic effects with latency periods of up to 24 h for chemicals and 21 days for pathogens. Lack of immediate clinical symptoms should not be taken as evidence that individuals have not been exposed. Even with a large exposure, pathogens will have an incubation period before signs or symptoms appear. Some agents are carcinogenic.
