Dietary exposure and urinary excretion of total N‐nitroso compounds, nitrosamino acids and volatile nitrosamine in inhabitants of high‐ and low‐risk areas for esophageal cancer in southern China

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.