Nitrate content of drinking water and tumours of the digestive organs

A survey of malignant tumours involving the digestive organs and the bladder registered in 7 districts and 5 towns in the County of Borsod was conducted. Between 1967 and 1983, the number of registered cases of tumours involving the digestive organs (including liver) was 3558 (incidence rate 691.6%) and that of bladder tumours amounted to 293 (incidence rate 56.9%). Males were more frequently affected than females with these types of tumour. Among the lesions of the digestive tract gastric tumours prevailed followed by tumours of the colon and of the rectum. The nitrate and nitrite contents of the drinking water consumed by the patients were also investigated. The average values were compared with the tumour incidence rate of the respective area. In most areas, the trend coincided i.e. lower morbidity was associated with lower average nitrate values. The data available revealed that about two-thirds (64.0%) of tumour cases affecting the digestive organs were living in areas where the nitrate concentration of drinking water was over 100 mg l-1. Analyses based on the various types of disease yielded similar results. The incidence of tumours in patients, drinking water with a nitrate content of 0 to 100 mg l-1 was 34.1 to 41.1%. The possible inter relationships between these figures are analysed and the implementation of additional epidemiologic and pathophysiologic investigations are suggested.