Most people would take the purity and hygiene of bottled waters for granted.
But just do they fare when put to laboratory tests for a host of chemicals and micro-organisms that may exist in bottled waters.
With the hot summer months just around the corner, the Consumer Council has conducted a massive test on 40 samples comprising 11 distilled waters, 4 mineralized waters and 25 natural mineral waters.
It sought to detect the presence of inorganic chemicals, heavy metals, pesticides, residual disinfectants, as well as to assess their microbiological quality. Highlights of the test results include:
First, 8 natural mineral water samples were detected with Heterotrophic Plate Count (HPC) in the range of 2 cfu/ml to 550 cfu/ml. HPC is a measurement of a wide spectrum of micro-organisms, including bacteria and fungi, which may occur in large numbers in raw water sources.
According to WHO Guidelines for Drinking Water Quality, HPC has little value as an index of pathogen presence but can be useful in operational monitoring as a treatment and disinfectant indicator in order to keep the numbers as low as possible.
There is no limit for HPC stipulated in the WHO Guidelines for Drinking Water Quality and Codex Standard for Natural Mineral Waters. In addition, HPC is not included as one of the microbiological criteria for bottled water stipulated in the Supplementary Information to Microbiological Guidelines for Ready-to-eat Food.
Although a higher HPC level could not directly indicate the presence of pathogens, doctors do suggest that young children, pregnant women, elderly and people with weaker immunity to choose drinking water carefully. Or, to boil natural mineral waters before consumption.
Second, 1 natural mineral water sample was found to contain nitrite in the amount of 0.4 mg/L, which was in excess of the limit (0.1 mg/L) set in the Codex Standard for Natural Mineral Waters.
According to the Joint FAO/WHO Expert Committee on Food Additive (JECFA), the acceptable daily intake (ADI) of nitrite is 0 - 0.07 mg/kg body weight.
This means an adult of 60 kg would have to drink more than 10 L of the sample per day to exceed the ADI of nitrite.
According to the Centre for Food Safety (CFS), there is currently no specific legislation to govern the level of nitrite in bottled waters. However, food sold in Hong Kong must be fit for human consumption.
Third, 2 natural mineral water samples were found to contain antimony, a toxic heavy metal, at concentration of 0.001 mg/L, which was well below the limit (0.005 mg/L) set in the Codex Standard for Natural Mineral Waters.
In the Food Adulteration (Metallic Contamination) Regulations, the maximum permitted concentration of antimony present in certain foods is specified. But bottled water is not listed as one of the specified foods.
Overall, all bottled water samples were not detected with pesticides, residual disinfectants and pathogens.
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