Yellow rain: chemical warfare in Southeast Asia and Afghanistan.

Circumstantial and laboratory evidence has accumulated supporting the use in Southeast Asia and Afghanistan of Russian-made lethal chemical agents. In this paper we will attempt to answer the question, "What is Yellow Rain?", summarize some of the massive data on microtoxins and mycotoxicoses, discuss the toxicology of the trichothecenes, give a brief historical perspective on chemical warfare, and touch on some of the political implications of these developments. The ubiquitous and insidious mycotoxins have been more or less causally linked to several human diseases, from ergotism to Reye's syndrome, as well as enormous livestock morbidity and mortality. We raise the concern that the Yellow Rain "experiments" pose the threat of massive use of chemical/biological warfare. The importance of an informed, vocal medical constituency cannot be overestimated.