Recently the U. S. Environmental Protection Agency (EPA) has identified naturally occurring and man-made fibers of respirable size, including cotton, as priority substances for review of health effects. The basis for this is a concern that respirable natural and synthetic organic fibers may cause lung diseases similar to those caused by asbestos and other mineral fibers. This paper reviews the literature linking man-made and natural organic fibers with ‘fibrogenic lesions' and lung cancer; and summarizes the relevant data with respect to cotton-related dust. Conclusions regarding the risk of developing fibrogenic lesions or lung cancer from exposure to cotton dust/fibers are offered: Epidemiological studies of textile workers and chronic inhalation studies have not shown that exposure to cotton-related dust can cause or is a risk for fibrosis or cancer; pathology studies (postmortem studies of long-term cotton mill workers) have shown no evidence of fibrosis or cancer and are consistent with chronic bronchitis.