Page:Popular Science Monthly Volume 84.djvu/33

Rh character of the work and the development of cancer. For instance in Röntgen ray technicians, especially in those who began their work, in the first years following the discovery of the rays, when the dangers connected with this occupation, the various precautions used at the present time were as yet unknown, gradually, often after many years of work, a painful condition of the skin arose, mainly on the hands and arms which were exposed to the rays, it became thickened, cracked, ulcers formed. The epithelium grew further down into the deeper tissues and slowly a carcinoma developed which later made metastases. Approximately 70 cases are known where cancer thus developed, and in some cases it developed a considerable time after the exposure to the Röntgen rays had ceased.

Chimney sweeps develop relatively frequently cancer of the skin, especially of the scrotum, and it is interesting that this cancer may be found in young people. It has for instance been observed in a boy eight years old. The cause of this cancer is the irritation produced by soot. Those who are employed in the distillation of tar (especially of gas work tar) in the manufacturing of grease and briquettes are liable to develop cancer of the skin. Certain organic substances contained in tar and pitch cause the development of warts on the skin, which later break down and become transformed into cancers. In men employed in the manufacturing of aniline dyes, and certain other benzol derivatives, wartlike excrescences of the skin may appear; but especially interesting is the frequent appearance of cancers of the bladder in such cases. Each of the affected men had been in the dye works for 20 years or more. Evidently substances excreted through the kidneys exert in such cases an irritating action on the epithelium of the bladder.

There are some other occupations in which certain substances are the direct or indirect cause of the development of cancer. Just as Röntgen rays and certain chemicals, so may also light rays under certain conditions be the cause of cancer, especially in sailors, in whom sometimes the skin of that part of the body which is exposed to the light shows certain changes which lead gradually to the development of cancer. We notice also occasionally in old people and in rare cases even in young men in the face and on the hands, in parts therefore exposed to the action of the light rays, the development of multiple lesions, which in the course of time become transformed into carcinoma. There occurs furthermore in children a congenital skin disease, xeroderma pigmentosum, which develops usually into a carcinoma at places exposed to the light rays.

Very instructive is the cancer which is not rarely found in Kashmir among the carriers of the kangri, a little stove, which burns the skin on which it rests. Gradually cancers develop in the scars; the downgrowth