The organization of food surveillance in the UK is described, in particular as it has been applied to preservatives and their interaction products in foods. Applications of nitrates and nitrites as preservatives are discussed, together with the consequential exposure of consumers to these anions and their reaction products. Analytical methods for the determination of volatile and non‐volatile N‐nitroso compounds are referred to in relation to the results in food surveillance studies. Concentrations of Apparent TotalN‐nitroso Compounds (ATNC) averaged 2900 μg(N‐NO)/kg in fried smoked bacon compared with 2400 μg/kg in fried unsmoked bacon; of this, known volatile and non‐volatileN‐nitroso compounds accounted for only 10–20%. ATNC were not detected in cheeses except those manufactured with added nitrate when ATNC levels up to 210 μg(N‐NO)/kg were detected. Further studies are needed to determine the identity and toxicological properties of the non‐volatileN‐nitroso compounds.