Document a4BvO0EgOVLBK9nY646ngQ4NN

SPECIAL ASPECTS OF OCCUPATIONAL TUMORS 759 years, scrotal cancer became manifest during the ages of 30 to 40 years. Fol lowing the introduction and partial enforcement of laws restricting the em ployment of infants in this occupation, the manifestation age of the chimney sweeps' cancer increased to 45 to 50 years from 1872 to 1892 (Butlin), and advanced still further during the subsequent decades (1911 to 1935), when the average age of chimney sweeps with scrotal epithelioma was found to be 61.9 years (Henry). The manifestation of the majority of sweep's cancers was delayed by 25 years after the various governmental regulations controlling the employment of boys in this profession had been made more strict, the starting age of employment had been advanced to 16 years, and sanitary and technical improvements and medical measures had been introduced, reducing the intensity of exposure and combatting effectively the precancerous lesions. While Earle and Pott observed scrotal cancer in climbing boys as young as 8 years old, and whereas these tumors were not infrequent in sweeps from 15 to 30 years of age at that time, soot cancer is nowadays not seen before the age of 30 years and is rarely found in individuals between 30 to 45 years old. Similar observations were made in England in connection with the mani festation age of paraffin and oil cancers. From 1911 to 1935 the manifestation age of this type of occupational tumor advanced by 12 years (1911-1915: 54.2 years average} and 1931-1935: 63.5 years average). Somerford attributed this development to the fact that the entrance age of the workers was formerly much lower, as it was a common custom to send children 9 to, 10 years old into the factories. Fibiger} Parodi; Doderleinj Leroux and Peyre; Bang} and Leitch em phasized the point that tissue senscence plays no role in the development of tar and pitch cancer. Pitch cancer is found in individuals between 19 to 79 years old, and tar cancer is observed among workers from 30 to 85 years of age. In a series of 362 tar cancers, 140 cases involved individuals less than 50 years old. Sladden showed that the incidence of pitch cancer among workers of patent fuel plants increased directly with the duration of employment paralleling the age of the workers, so that ultimately in the oldest group 100 per cent of the workers were affected by pitch epitheliomas. While the age distribution of occupational arsenic cancer does not reveal any remarkable shift into younger age groups, such a phenomenon is prominently displayed by the non-occupational type of arsenic cancer (range: 10 to 80 years). Twenty-four out of 39 therapeutic arsenic cancers were in individuals less than 40 years old. Pye-Smith stated that 25 per cent of all therapeutic arsenic cancers affect individuals less than 3 5 years of age, while Ullmann found that this type of malignancy was usually seen before the age of 40 years. Occupational caricer of the bladder of chemical or parasitic genesis is char acterized by an age incidence which favors the younger age groups (aniline' cancer: 52.4 per cent of all cases in individuals less than 50 years old} and