Five of the top nine pesticides used on cotton in the U.S (cyanide, dicofol, naled, propargite and triflurin) are known cancer-causing chemicals.

Cyanide, Dicofol, Naled, propargite, trifluralin are all toxic isecticides that are used while growing the cotton crop. Classified by the EPA as Category I or II, the most dangerous categories of chemicals.

Cyanide:  The most hazardous compound is hydrogen cyanide, which, because it is a gas at ambient temperatures and pressure, can be inhaled. A supplied air respirator must be worn when working with hydrogen cyanide. Hydrogen cyanide is produced when a solution containing a labile cyanide is acidified because HCN is a weak acid; alkaline solutions are safer to use because they do not evolve hydrogen cyanide. Hydrogen cyanide may be produced in the combustion of polyurethanes; for this reason, polyurethanes are not recommended for use in domestic and aircraft furniture. Oral ingestion of a small quantity — typically 200 mg — of solid cyanide or cyanide solution, and airborne exposure of 270 ppm may lead rapidly (within minutes) to death.[17]

^ Biller, José (2007). Interface of neurology and internal medicine (illustrated ed.). Lippincott Williams & Wilkins. p. 939. ISBN 0-781-77906-5., Chapter 163, page 939

Dicofol: Tests on laboratory animals show that the primary effects after long term exposure to dicofol include increases in liver weight and enzyme induction in the rat, mouse and dog.

There are also effects relating to altered adrenocorticoid metabolism (part of the hormonal system). In the rat hormonal changes were accompanied by the histological observation of vacuolation (empty cavities) of the cells of the adrenal cortex.

Naled: “Naled can cause cholinesterase inhibition in humans; that is, it can overstimulate the nervous system causing nausea, dizziness, confusion, and at very high exposures (e.g., accidents or major spills), respiratory paralysis and death.  http://www.epa.gov/oppsrrd1/REDs/factsheets/naled_fs.htm