M.Sc. Rajesh Dikshitin kansanterveyden alaan kuuluva väitöskirja
Lung,Oropharynx and Oral cavity cancer in Bhopal : An epidemiological study (Keuhko-, suunielu- ja suuontelosyöpä Bhopalissa: epidemiologinen tutkimus)
tarkastetaan perjantaina 17.4.1998 klo 12 Tampereen yliopiston terveystieteen laitoksen T-rakennuksessa, osoitteessa Medisiinarinkatu 3.
Vastaväittäjänä on tohtori Timo Partanen Helsingin työterveyslaitokselta. Kustoksena toimii professori Suvi Virtanen.
Dikshit on syntynyt Indoressa Intiassa 1964. Hän on suorittanut Master of Science -tutkinnon Devi Ahilyan yliopistossa Indoressa 1985. Dikshit on toiminut vuodesta 1986 lähtien tutkijana Bhopalin Syöpärekisterissä.
Dikshitin väitöskirja ilmestyy sarjassa Acta Universitatis Tamperensis, Vammalan Kirjapaino Oy, Vammala 1998. ISBN 951-44-4326-8. ISSN 1455-1616
Väitöskirjan tilausosoite: Tampereen yliopiston julkaisujen myynti, PL 617, 33101 Tampere, puh. (03) 215 6055.
Lisätietoja: Suvi Virtanen, puh. (03) 215 7801 (työ).
A chemical disaster caused by a gas leak from the Union Carbide factory at Bhopal on the night between 2nd and 3rd December 1984, took around 2,000 lives and the population is still suffering with the various medical problems in the capital city of the state of Madhya Pradesh, India. The gas which leaked from the tank of factory was mostly methyl isocyanate (MIC). Since MIC has toxic and potential carcinogenic properties, it generated the concern regarding risk of cancer induced as a consequence of the gas exposure at Bhopal. The present study was undertaken to shed light on carcinogenic effects of gas exposure and to study the etiological role of bidi smoking and chewing with or without tobacco in the causation of oral cavity, oropharynx and lung cancer. Indian bidis are kind of cigarette which contains tobacco rolled in a leaf of 'tendu' tree. Bidi contains higher concentration of several toxic substances compared to US cigarette including nicotine and tar.
During the year 1987-1992, increase in lung cancer was observed, whereas no staistically significant changes were seen for oropharynx and oral cavity cancer. No excess risk for the site studied was found to be associated with the gas accident at Bhopal till the year 1992. However, it is possible that the full potential of excess risk,if any, will manifest only 15-20 years after the accident as occurence and detection of malignant tumour may take long time.
Bidi smoking was found to be equally as hazardous as cigarette smoking in causation of lung and oropharynx cancer. The risk for bidi and/or cigarette smokers were marginally increased for oral cavity cancer. The tobacco chewing appeared to be factor associated with oral cavity cancer. The slightly elevated risk for oral cavity cancer even among those who chewed without tobacco was observed.
The study suggest that greater part of cancer of most common cancer site in Bhopal could be prevented by controlling for the smoking and tobacco chewing habits. The intervention studies for giving up of tobacco habits will have much relevance in Bhopal as in this population the lungs are already damaged to some extent due to gas exposure. Even if gas exposure proves to be carcinogenic in future, by preventing the use of tobacco, large number of cancer cases can be prevented.