Investigation of Heavy Metals, Nitrate, and Nitrite in The Commonly Available Commercial Packed Drinking Water in Mashhad, Iran

Abstract

Background: Due to the increasing consumption of bottled water in recent years, to ensure the safety, we aimed to evaluate the concentration of 6 toxic heavy metals, nitrate and nitrite components in the commonly sold bottled water in Mashhad, Iran.Methods: The 11 best-selling bottled water brand in Mashhad were identified. Eight bottles from each brand were randomly collected and delivered at the same day to toxicology laboratory of Imam Reza Hospital and refrigerated at 4-6 °C. Spectrophotometry and atomic absorption spectrometry and were used to measure the nitrate, nitrite and heavy metals, respectively. The results were analyzed by SPSS version 16 and compared with the WHO and Australian guidelines. Also, the discrepancy between measured components and the depicted labels’ values were compared.Results: The mean and SD of concentrations of the heavy metals in 11 brand were as below: lead 1.62±0.86 [µg/L], chromium 1.03±0.84 [µg/L], cadmium 0.17±0.07 [µg/L], mercury 3.86±1.57 [µg/L], arsenic 0.89±0.46 [µg/L], aluminum 6.56±4.54 [µg/L]. The mean and SD measured quantities of nitrate, nitrite and pH were 9.96±5.95 [mg/L], 0.01±0.03 [mg/L] and 7.92±5.95, respectively. There was a significant difference between the label values and the quantitative levels except for 3 brands, which was observed with a p value of 0.518 and 0.642 for nitrate level in N4 and N11 brands, as well as 0.681 for pH level in N7 brand. The measured values of heavy metals, nitrate and nitrite in all samples were within domestic, WHO and Australian limits, except for mercury in 9 samples which exceeded the Australian standard [less than 1 µg/L].Conclusion: The heavy metals, nitrate and nitrite concentrations in all samples were within the domestic, WHO and Australian ranges, except for mercury in 9 samples that exceeded the Australian standard. There was a discrepancy between entries of the bottled labels and the measured quantities.

Keywords

• water contamination
• toxicology
• heavy metal intoxication
• instrumental analysis