Conditions for ingestion and organ content studies: Summary of data submitted by questionnaire

In China, food materials are blended locally and frozen for transport. Most participants will food materials in polyethylene containers by land or by air under refrigeration without any preservative such as formaldehyde. In most centres, a 'conventional' laboratory is used for sample preparation, but with additional facilities to prevent contamination of samples. A constant temperature electric oven, or vacuum drier if available, and blender (or mortar and pestle for some limited purposes) are being used. A blender with titanium blades is felt preferable by participants. In India, Indonesia, Korea, Pakistan and Vietnam (and probably in Bangladesh), NAA is used for most of the first priority elements, and PIXE for some elements. In China, Japan, Malaysia and Philippines, atomic absorption spectrometry, and ICP emission and mass spectrometry are to be employed. However, INAA or RNAA for iodine determination as well as PIXE are also used. For the latter case, samples are generally ashed in a muffle furnace with special care against inclusion of foreign materials; acid decomposition is accomplished with a borosilicate glass beaker and watch glass on a hot plate, and mostly using analytical grade acids. A PTF crucible or pressure vessel with an electric or microwave oven and high purity acids will be useful for ICP-MS determination of Th and U. Standardization procedures should be clearly described, such as the use of standard solutions or the preparation of laboratory standards for neutron irradiation or PIXE measurements. In general, natural matrix reference materials should not be used as calibration standards. Water used, partly in sample preparation, and in chemical analysis is mostly distilled and/or deionized water. Doubly distilled or doubly deionized water is also used. A laminar-flow clean bench (preferably with exhaust function for protection against acid fumes and biological hazard) was previously recommended. However, as also stated before, a conventional laboratory is still usable with care provided that it is segregated or separated from ordinary laboratories where chemicals containing metals and elements of interest are routinely used