RELATIONSHIP BETWEEN DRINKING WATER, VEGETABLES AND CANCER DEATH IN THE HIGH INCIDENCE AREA OF DIGESTIVE TRACT CANCER

The paper analyzed of investigation datas on the death causes of digestive tract cancer in high-incidence area between 70s and 80s. The results showed that the cancer-adjusted mortalities were 224.14/100000 and 226.66/100000; it was 7 times as high as low-incidence (31.19/100000 and 29.82/100000). In 70s, the cancer death of esophagus, stomach and liver (87.41/100000, 73.93/100000 and 8.59/100000) were 28 times, 10 times and 4 times as high as low-incidence area (3.70/100000, 10.57/100000 and 1.94/100000), respectively (P<0.001). In 80s, the cancer death of esophagus, stomach and liver (68.26/100000, 109.39/100000 and 23.89/100000) were 17 times, 10 times and 4 times as-high as low-incidence area (4.54/100000, 10.84/100000 and 6.35/100000), respectively (P<0.001). In high-incidence area, the cancer death of esophagus was lower, of stomach and liver were higher in 80s than 70s, respectively (P<0.01). The result also showed that the nitrate content of drinking water and vegetables were 21.45mg/I and l185.27mg/kg in highincidence area; it were significant higher than that in lowincidence area (2.14mg/I and 41.60mg/kg), the nitrite content (0.01mg/I) of drinking water in high-incidence area was significant higher than that in low-incidence area (0.004mg/I), but the nitrite content among vegetables was no significant difference between the two regions (P>0.05). Our results suggest that the nitrate and nitrite contents increase in drinking water and vegetables may be an important risk factor of upper alimentary cancer in high-incidence area.