Abstract

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In total, 201 duplicates of all foods and drinks sampled by adult volunteers during a 24-hour sampling period have been analyzed for nitrate, nitrite and volatile N-nitrosamines. For nitrate the mean daily intake was equivalent to 179 mg of potassium nitrate per 24 h, for nitrite this intake was equivalent to 4.2 mg of sodium nitrite per 24 h. The best estimate for the total daily fraction of salivary nitrite originating from dietary nitrate has been calculated as 6.3 mol%/24 h. For N-nitrosodimethylamine the mean daily intake was 0.38 μg/24 h. The most important source of this nitrosamine contributing to the daily dietary intake was shown to be beer, which contributes 71% of the intake of an average consumer. Finally, attention has been drawn to the identification of N-nitroso-5-methyl-l,3-oxazolidine as an environmental nitrosamine present as an impurity in cutting fluids.

No abstract

Aflatoxins are the only food contaminants being monitored routinely on an international scale with methods operating at the order of magnitude of 10 μg/kg. At this concentration level, methods of analysis which can achieve coefficients of variation of 30–40% with recoveries of 70% or greater in interlaboratory collaborative studies can be considered eligible for referee status. In most cases, sample reproducibility is the variable limiting the reliability of methods of analysis. The inherent uncertainty of the identity of chromatographically separated entities requires the application of confirmatory tests to verify that the characteristic measured results from the presence of aflatoxin. The methods are also inoperable without a verification of the identity, purity, and concentration of the reference standards used. Screening methods which reliably eliminate negative samples from further consideration are indispensible for the practical operation of monitoring programs.