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We assessed the exposure of total N-nitroso compounds (TNOCs) in the inhabitants of high- and low-risk areas for esophageal cancer in southern China. Samples of 24 hr diet and 12 hr overnight urine were collected from 120 male adults in each of the 2 areas, a high-risk area (Nan'ao County) and a low-risk area (Lufeng County) for esophageal cancer. Annual standardized mortality rates of esophageal cancer in Nan'ao and Lufeng are 110/10(6) and 10/10(6) respectively. The 240 healthy male subjects (35-64 years old) were selected by a 3-stage random cluster sample procedure. Levels of TNOCs, NAAs and volatile nitrosamines in the samples were measured. The TNOC detection rate (95%) in the diet, the TNOC daily intake (4.25 +/- 0.84 micromol), TNOC excretion levels (0.04 +/- 0.01 nmol/12 hr) and daily intake of volatile nitrosamines (5.84 +/- 0.71 micromol) in the high-risk area were significantly greater than values in the low-risk area (A +/- B = mean +/- SE). The TNOC detection rate in the diet, the TNOC daily intake, TNOC excretion levels and daily intake of volatile nitrosamines in the low-risk area were 70%, 0.25 +/- 0.06 micromol, 0.02 +/- 0.01 nmol/12 hr and 3.18 +/- 0.31 micromol, respectively. NAA excretion levels showed no difference between the 2 areas (16.3 +/- 7.18 micromol/12 hr for Nan'ao and 31.2 +/- 26.4 micromol/12 hr for Lufeng). Thus, TNOCs are implicated in the etiology of esophageal cancer in southern China., (Copyright 2002 Wiley-Liss, Inc.)

Cancer patients show a salivary NO2- density that is twice that of healthy individuals. This indicates that endogenous NO2- is correlated with the cancer. By applying a culture medium modified by vitamin B1 or KCIO3, we have found that many bacteria in the human body (especially the bowels) can nitrify NH4+ to NO2-. NO2- can be combined with a second amine to form nitrosamine which is a carcinogen. We fed mice using G+ coccus, which can lead to a precancerous lesion and mammary carcinoma, and proved that nitrification in vivo is carcinogenic. We have tested a method to prevent cancer in 7392 workers. Patients with a salivary density of NO2- over 10 ppm for 3 consecutive days and with light symptoms were our targets for preventive treatment using antibiotics and nitrosamine destroyers. The result shows that the average cancer incidence rate in the control group is 58.4% higher than in the experimental group over 9 years. The difference between the two groups is statistically significant (x2 = 8.5, p < 0.01). This is reliable evidence that preventive treatment is effective when based on the idea that endogenous NO2- and nitrosamine are the carcinogens.