Analysis of nitrite and nitrate in foodstuffs-method development, ocurrence, regulation, metrological aspects and exposure

Resum

Nitrite and nitrate occurrence in food and suitability as food additive are a controversial issue. Nitrite is an approved additive considered a foremost curing ingredient for the preservation of meat products. Nitrate is a natural constituent of the human diet that, however, raises concern for its suggested potential harmfulness related to cyanosis condition, carcinogenesis and environmental contamination. Therefore, reliable nitrite/nitrate determination is necessary for three main reasons: a) to assess compliance with current regulations on additives and contaminants, b) to determine the content of nitrite/nitrate in individual foodstuffs, diets and water and c) to study the fate of nitrite/nitrate in biological fluids. This thesis summarizes the work on analytical research, regulations enforcement and exposure estimate on nitrite/nitrate in vegetables and meat products carried out at the Swedish National Food Agency. The work undertook a series of studies: First, select and standardize an HPLC-Ion Chromatography method for the determination of nitrite/nitrate in foodstuffs. This method was used to generate data of the occurrence of nitrate in Swedish produced vegetables contributing to the discussion on t he European regulation setting maximum levels for nitrate in lettuce and spinach. Second, an alternative environmental friendly spectrophotometric method was developed to gather data on the content of nitrite/nitrate in meat products in the Swedish market. Actually, these analytical methods are European (CEN) and Nordic (NMKL) official methods, respectively. The collected data plus data from consumption of vegetables, fruit and drinking water was integrated with a nationwide food consumption survey (4-day food diary) to estimate the total intake of nitrate and nitrite in Swedish children and adults. The Acceptable Dairy Intake (ADI) approach applied, which included the nitrite intake from all dietary sources and the endogenous nitrate-nitrite conversion, suggest that the international approach currently used to estimate the ADI causes an underestimation of the real nitrite intake with potential health-relevant risk.