by Hidenori Yokoi
At the Toroku mine and refinery in Miyazaki, Japan, white arsenic was
intermit-tently produced by calcinating arsenopyrite for about 28 years between
1920 and 1962. The health damage to nearby residents resulted from this was
officially recognized in 1973 by the Pollution Health Damage Compensation Law.
Even at this point, Dr. Shinkan Tokudome et al. indicated that many cases of
lung cancer had been observed among the residents (*1).
Following this, reports from case and follow-up studies werde made on cancers in Toruku. One of the best among these is, "An Epidemiological Study on Cancer in Certified Arsenic Poisoning Patients in Toroku" (*2) by Toshihide Tsuda (now Assistant Professor, School of Medicine, Okayama University), Tsuyoshi Nagira, et al. of Oita Kyowa Hospital. The subjects of this study were the 141 patients certified as suffering from arsenic poisoning between 1972 and 1989. There were 70 males and 71 females; 85 ex-workers and 56 residents; the four who died within one year of certification were excluded. The study reveals cases of cancer among the 53 deceased and describes some related implications.
According to the report, 16 deaths (just over 30%) were caused by cancer, and among them 8 were lung cancer and the others were one case each of laryngeal carcinoma, carcinomatous pleuritis, ureteral carcinoma, urethral carcinoma, non-Hodgkin's lymphosarcoma, angiosarcoma of the skin, breast cancer and rectum carcinoma. Among those who died from lung cancer, one was accompanied by adenocarcinoma of the stomach, and another by adenocarcinoma of the prostate. The one who died from laryn-geal carcinoma was accompanied by basal cell carcinoma of the skin. It is also reported that there were 26 cases (49%) of Bowen's disease among the 53 deceased and that seven of them were accompanied by respiratory cancers, two were accompanied by urinary tract cancers, one by breast cancer and another by lymphosarcoma.
By April 1996, 157 from Toroku were certified as suffering from arsenic poisoning and 81 had already died. During the six years after the report by Tsuda et al. 26 more passed away while 12 were newly certified. Of the 81 deceased, at least 24 died from cancer. Moreover, there are certified cases of cancer among the survivors and some who were cured of cancer then died from other arsenic related illnesses.
In July 1996, the Japanese Environ-mental Agency added "epithelium carcinoma on the urinary tract including the bladder" to the criteria for compensation for chronic arsenic poisoning. Till then, the Agency had admitted only skin, lung and liver cancers as caused by arsenic. This long awaited addition provides some much deserved recognition of the long struggle by Toroku victims. Unfor-tunately, there have been two more patients suffering from urinary tract cancer in addition to the two cases reported by Tsuda et al., one having already died in December 1994.
The first two victims of urinary tract cancer were ex-workers. The one who died in 1978, at the age of 55, had worked for 11 years at the refinery and developed the disease 41 years after he began work there. The other one, who died in 1980 at the age of 67, was diagnosed after a latency period of 52 years. There are many reports on the various malignant neoplasms as late effects of arsenic exposure. In Toroku, too, there are various cases of cancer as delayed symptoms of chronic arsenic poisoning, and it remains as a grave problem even today.
*1) A report by the Professional Committee for the Social
Medical Survey on the Toroku District, chaired by Masanori Kuratsune, Professor,
Kyushu University School of Medicine (July 1972).
*2) Published in the "Industrial Health" (Vol. 28, 1990), an English quarterly issued by the National Institute of Industrial Health, Kawasaki, Japan.