Document zoNwrVEKvEywbgBRLagvGwaka

102 OCCUPATIONAL TUMORS AND ALLIED DISEASES Gas Works: Other Industries: 55 cases of epithelioma 75 46 cases of epithelioma 35 21 deaths 1920-1927 38 1933-1937 6 deaths 1920-1927 7 1933-1937 Including the cases which occurred during the year 1929, the percentage of fatalities from tar and pitch cancer among English workers affected by this disease presents itself as follows: pitch cancer: 336 cases with 11 deaths} tar cancer : 602 cases with 112 deaths. This compilation brings out the interesting fact that tar cancer offers a much worse prognosis than pitch epithelioma. At the present time a plausible explanation for this phenomenon cannot be offered. The possibility exists that the physico-chemical properties of tar enable a better and deeper pene tration of the carcinogenic agent into the cellular layers of the skin, than those of pitch, occurring mainly in the form of dust. As this observation is based entirely on English data, consideration must be given to the fact that tar apparently produces scrotal malignancy more often among English workers (Bridge and Henry) than among continental workers. This fact may account in part for the bad prognosis of tar cancer in England. VIII. AGE It has been maintained by various observers that advanced age represents an intrinsic, predisposing factor for development of cancer of the skin in individuals exposed <to tar and pitch (Teutschlaender). They have, therefore, warned, against the employment of such individuals in tar and pitch opera tions. Other investigators have maintained that duration of exposure rather than absolute age, that is, a hypothetical tissue senility, plays the chief role in the production of tar and pitch malignancy (Kennaway). The following tables illustrate the age distribution of pitch papillomas, pitch cancer, and tar cancer as it is presented by a survey of data available. Years Cases AGE DISTRIBUTION OF PITCH WARTS (Downing) 21-30 31-40 41-50 51-60 61-70 Total 4 9 24 . 16 8 61 AGE DISTRIBUTION OF PITCH AND TAR EPITHELIOMAS Years Pitch Cases Tar Cases 80 15-19 20-29 30-39 40-49 50-59 60-69 70-79 and Total more y" 1 5 H 34 38 20 3 115 6 14 15 32 12 1 80