CHARLES JOHANSEN 



Hgb. percentage of about 30. In the course of 2 years he received about 65 blood 

 transfusions, but then died of agranulocytosis with sepsis and severe haemosiderosis. 



(2) A woman, aged 37. who 7 years earlier had received an injection of a quantity 

 of thorium equivalent to 1 to 2iJig of radium. She died of typical myelosclerosis. 



(3) A man. aged 60, who 10 years earlier had had a dose of thorium deposited 

 which was equivalent to 1 jjig of radium. He died of chronic myelogenic leukaemia. 



(4) A man, aged about 40, who died of stem-cell leukaemia 14 years after he had 

 been contaminated with a thorium dose equivalent to 2[i.g of radium. 



On the other hand, our series showed no increased incidence of cancer and 

 contained no cases of maHgnant tumours whose occurrence could be reason- 

 ably attributed to the thorium contamination. 



In experiments on rabbits I have given intravenous injections of doses of 

 thorium equivalent to from • 005 to • 1 25 [xg of radium per kg. Hitherto, 

 none of these animals have presented leukaemic changes, but so far the 

 cause of death in 8 animals has been a disseminated, malignant tumour, 

 a reticulo-endothelio-sarcoma. These animals had all been given doses of 

 thorium equivalent to 0-07(j.g of radium per kg, or more, and they died 

 between 2 and 3 years after the injection. Presumably a much greater 

 number of animals in the groups will present this form of tumour, since, so 

 far, all animals which received these doses and died more than 2 years after 

 the injection had this tumour as cause of death. None of the controls 

 has presented tumours of any kind. With regard to the malignancy of the 

 tumour, there can be no doubt, as it can be transplanted. After intra- 

 muscular injection of tumour tissue, cortisone-treated animals showed tumour- 

 cell emboli in the pulmonary capillaries a few days later, and a few animals 

 have had tumours in the lungs. 



Exactly the same form of tumour has been found in human beings in three 

 cases, all following injection of thorium into the blood-stream. Horta's^ 

 and Liidin's* patients thus died 3 and 14 years respectively after injections 

 of thorium doses equivalent to about ly.g of radium, and MacMahon's^ 

 patient died 14 years after injection of a dose corresponding to about 4[xg 

 of radium. This last-mentioned patient died of intraperitoneal haemorrhage 

 after spontaneous rupture of the tumour, and I may mention that 2 of my 

 rabbits showed the same cause of death. This form of tumour may thus 

 occur in both man and rabbits, and is presumably one that is specific of 

 thorium deposition in the parenchymatous organs. It may therefore seem 

 strange that we have not observed one case of this tumour in our series of 

 about 250 persons. In my opinion this is just a question of time. Our 

 series exclusively comprises persons who were contaminated with thorium 

 from 4 to 16 years ago, and we know nothing definitely about the length of 

 the period that will pass before radiation-induced tumours in man manifest 

 themselves clinically. 



Several scientists, however, suggest that radiation-induced cancers will 

 appear from 10-30 years after the contamination with an optimum time of 

 16 years. If we acknowledge this assumption the following calculations may 

 give an idea of the cancer problem for our patients. In Figure 1 the block 

 diagram to the left gives absolute numbers of patients as ordinates and 

 years after contamination as abscissa ; it is first noted that only 3 of the 

 patients have passed the 16-years limit. To the right a Gaussian-like curve 



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