Mule spinners' cancer and the wool industry.

Although mule spinning has been used in the cotton and wool industries for about two centuries, the earliest recorded cases of mule spinners' cancer were not reported until the end of the nineteenth century. From then on the number of cases rapidly increased. Evidence accumulated which strongly suggested that the mineral oil used to lubricate the mule spindles was the cause. It is remarkable that mule spinners' cancer was almost entirely confined to the cotton industry, and the wool industry has escaped with very few cases. This difference has never been satisfactorily explained. Various possibilities related to the personnel, the plant, and the process are examined in this paper.