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

Abstract

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.