[Editor's Note] The purpose of this special session was to review and discuss the sampling for and measurement of endotoxin. The session was recorded and a best effort has been made to be true to the discussion.

I would like to welcome you to the last session of this year's Cotton Dust Conference. This special session was organized by Phil Wakelyn and is intended to address the measurement of endotoxin in cotton dust. We have heard a number of reports that have evaluated endotoxin in cotton dust. However, in focussing this session on the measurement of endotoxin we should not exclude some of the other types of biologically active materials we have heard about at these meetings, for example tannin. These other constituents of cotton dust are likely to be important actors in the response to cotton dust and their measurement should concern us as much as endotoxin.

When we speak of cotton dust we are not talking about bulk dust but what you find in the air. Thinking back through our collective experience of working with cotton dust, what have we measured in airborne samples? We've measured gravimetric dust (that's a given, we've got a standard based on that); we've measured endotoxin; and we've measured airborne bacteria. That's it! No other agents have been measured in airborne dust. In the middle seventies there were a number of papers that described the different constituents of cotton. These papers described hundreds of natural products in cotton, none of which have been measured in airborne dust. Many of these natural products are produced by the plant as a response to past pressure and therefore are biologically active chemicals. To further complicate the matter, cotton probably has more pesticides used in its production than any other single crop in the United States. So you've got a tremendous number of chemicals that are toxic to pests that are normally produced by the cotton plant as well as man-made constituents to assist nature. Some of those natural chemicals are tannins. No one has measured tannins in airborne samples. We do know from the data presented at this and other meetings that tannins are toxic. So, I want to introduce the session by focussing on the measurement of endotoxin, but I want us to keep in mind the other constituents in cotton dust that have never been measured.