This study investigated the association of a tobacco-specific nitrosamine carcinogen,4-(methylnitrosamino)-l-(3-pyridyl)-l-butanol (NNAL) with urinary cotinine (uCot),urinary sodium (uNa) excretion,systolic blood pressure (sBP),and total energy intake in adolescents and children in relation to the subjects\' age.A total of 790 subjects aged 6-19 years were evaluated.NNAL,uCot,corrected NNAL (cNNAL),the NNAL/uCot ratio,uNa,sBP,and nutrient intake were measured.A strong association between uCot and cNNAL was observed in children who were 11 years of age (r=0.881,P＜0.001);however,no significant association was noted in adolescents who were 19 years of age.The uNa level was significantly higher (133.9 mmol/L vs.107.8 mmol/L,P＜0.001) and sBP was significantly lower (105.3 mmHg vs.110.6 mmHg,P=0.012) in adolescents with elevated NNAL than in those without elevated NNAL.NNAL was significantly higher in subjects with increased uNa excretion than in those without increased uNa excretion.NNAL was positively correlated with uNa (r=0.183,P＜0.001) and negatively correlated with sBP (r=-0.142,P＜0.001).Non-smokers with elevated NNAL/uCot ratios had significantly lower total energy intake than those without elevated NNAL/uCot ratios (1729.0 kcal/day vs.1911.0 kcal/day,P=0.008).The relationship between NNAL and uCot varied according to the subjects\' age.NNAL seems to play a role in decreasing sBP by enhancing uNa excretion.Insufficient nutrient intake may contribute to endogenous formation of NNAL in non-smoking adolescents and children.