Detection of methylating activity due to nitrosamide in some nitrosated nigerian foodstuffs

Popular vegetables, condiments and some Nigerian staple foods were evaluated for their relative methylating potential due to nitrosamide formation following nitrosation under standardized conditions. Methylating activity of nitrosated foodstuffs, expressed as N-nitroso-N-methylurea equivalents, was determined by gas chromatography-thermal energy analysis. In positive samples (detection limit 10 μg/kg) methylating activity detected was in the range of 50–1200 μg/kg, the highest activity being found in Telfairia occidentalis (ugwu). This value constitutes the highest amount ever detected for a fresh vegetable. The data suggest that some commonly consumed local foodstuffs might contribute to overall human burden of environmental carcinogens in Nigeria.