PubMed · 758509
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P R Garrett. 1979-01-12. Threshold theory vs linear theory.. https://doi.org/10.1001/jama.241.2.135b
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A simple method for the spectrochemical analysis of water samples by inductively coupled plasma spectrometry is described. Samples from drinking water coolers in 32 schools in Riyadh were collected at a specific time during a typical school day and analyzed for aluminum (Al), beryllium (Be), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), silicon (Si), strontium (Sr), vanadium (V), and zinc (Zn) to ascertain the water quality. The analysis of drinking water showed high concentrations of metals and in some cases exceeded the guideline limits recommended by EEC and WHO.
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The purpose of the study was the assessment of nitrate content in vegetables and potatoes in relation to the acceptable levels of nitrates. The samples for the study were taken by workers of the Province Sanitary- Epidemiological Stations in 39-42 provinces, depending on the season of sampling. The samples were taken from retail shops. Nitrate content was determined by spectrophotometry after previous reduction in cadmium column. The study was conducted in the years 1987-1991. A total of 13,075 samples were analysed. The nitrate levels in excess of the acceptable values were found in 3.2 to 49.9% of the samples, depending on vegetable species. In the case of all vegetables and potatoes the value of the median of the nitrate content was never above the acceptable level. Permanent and systematic control of nitrate levels in vegetables and potatoes is mandatory.