Tapping into Shanghai’s Water Secrets
I recently read an article in the news, ‘2,800 Pigs Dumped in Shanghai River Raises Concern’, which lead to me questioning the pollution levels in Shanghai’s waters. Living in Shanghai, everyday I face a dilemma I always found to be rather minimal, whether or not to drink the water from the tap or to not be lazy and climb the four flights of stairs down to the nearest bottled water dispenser. As I had previously lived in countries such as England, and Japan, where clean water is abundantly available from taps, I assumed that Shanghai’s tap water could not have a large concentration of pollutants within its waters. I used to drink water in Shanghai from the tap, arguing that if anything, the exposure to these unknown particles would harden my immune system, like a child playing in the soil.
About 80% of the water we get in Shanghai is from the Huangpu River. The remaining 20% comes from the Yangtze River. On the list of the most polluted rivers in the world, the Yangtze and the Huangpu are both mentioned, with the Yangtze River Water Resources Commission report noting the total volume of sewage emptied into the Yangtze river totaling approximately 20 million tons. Noteable pollutants within the Shanghai river water are chlorine, heavy metals such as lead, nitrates and bacteria. (WHO, 2011)
Chlorine, a highly efficient disinfectant, is added to water for cleaning purposes, “Chlorine has been hailed as the savior against cholera and various other water-borne diseases, and rightfully so,” says Steve Harrison, president of water filter maker Environmental Systems Distributing. “Its disinfectant qualities…have allowed communities and whole cities to grow and prosper by providing disease-free tap water to homes and industry.” (About.com, 2010) However, Chlorine is defined by the American journal of Public Health to cause “significant increases in certain types of cancer, asthma and skin irritations” (American Journal of Public Health, 2011) . When combined with organic matter found in rivers, chlorine undergoes a chemical reaction to form products such as trihalomethanes (THMs) which is are known carcinogens (a substance capable of causing cancer in living tissue). Chlorine converts chemically by replacing three of the four hydrogen atoms of methane (CH4) with chlorine halogen atoms to produces these THMs. Due to the high levels of bacteria caused by improper dumping of sewage and other biological contamination, Chinese departments of water works simply use more chlorine.
Similarly to chlorine, lead is also extremely dangerous as it is toxic even in the amount of micrograms when entering the body, and leads to higher blood pressure, kidney dysfunction, anemia and colon cancer in adults. Nitrates found in the river water enter through organic runoff such as through fertilizers. These nitrates entering the readily available tap water can be fatal to children under the age of six months, as they cannot perform the chemical process shown below in their stomachs to convert nitrites into nitrates. (Sigler, 2010)
2NO2 –(g) + 2OH –(aq) –> NO3–(aq) + H2O(l) + NO2 –(aq)
If nitrites are not converted into nitrates, this poses a problem as in the early stage of development, nitrite reacts with hemoglobin, which is responsible for the transfer of oxygen, and prevents this transport. Evidently, the effect of this is a decreased oxygen supply to the body, well known as blue baby syndrome (or methemoglobinemia). Nevertheless, it should be known that this condition is very rare.(WHO, 2011)
I believed that by simply boiling Shanghai’s water, it would be safe to drink as boiling kills bacteria and parasites. After researching, I noted that boiling water doesn’t get rid of pollutants. There are plenty of solutions to the issue, for example, the establishment of sediment filters are an inexpensive way to physically trap particles, especially those of a filter size of 1 micron or smaller. (NRDC, 2009) However these filters still do not filter out chemical contaminants. The use of bottled barreled water, though expensive, are generally safe when from a reputable source. Furthermore, Activated carbon filters process most physical contaminants out, such as chlorine, and are EPA approved. Obviously, the key way to target this issue would be to stop it at the core, by removing pollutants from the lakes and river themselves. (WHO, 2011)
To fully assess the risk of drinking Shanghai’s water, we must note that there is a cleaning system to filter the water of the majority of the pollutants. When reading Nick’s post, he noted a water filtering company, Veolia, who first extract their water from underground aquifers and surface water bodies. All the water then passes through a purification process, which includes coarse and fine screening, flocculation and settling, filtration, ozonation and chlorination. (Veolia Water, 2010).These processes can all be explained in further detail in Nick’s blog post. Despite all these processes, nitrates still persist within the water, and hold particular risk to small children, as noted earlier. However, for me and the general population, water pollution holds quite a low risk to our health as it has been filtered numerous times before reaching our taps. The only real risk with Shanghai water is with the concentration of pollutants, not the pollutants themselves. Detrimental health risks only occur in situations in which the concentrations of these pollutants are very high, which is more likely in lesser developed countries, more rural areas, than in Shanghai itself.
About.com (2010). Why is Chlorine Added to Water. Retrieved April 20, 2013 from http://environment.about.com/od/earthtalkcolumns/a/chlorine.htm
Adam Sigler (13 March, 2010). Nitrate/Nitrite Fact Sheet. Retrieved March 19, 2013, from http://waterquality.montana.edu/docs/homeowners/nitrate_fact_sheet.shtml
American Journal of Public Health (2011). Stabilization of Chlorine in Water . Retrieved March 11, 2013, from http://ajph.aphapublications.org/doi/abs/10.2105/AJPH.32.9.1025?prevSearch=chlorine&searchHistoryKey=
NRDC. (2009). Water. Retrieved April 20, 2013, from http://www.nrdc.org/water/
WHO . (January 1, 2011). Nitrate and Nitrite in Drinking Water. Retrieved March 11, 2013, from http://www.who.int/water_sanitation_health/dwq/chemicals/nitratenitrite2ndadd.pdf
WWF Global. (25 October 2010). Threat of Pollution in the Yangtze. Retrieved March 11, 2013, from http://wwf.panda.org/about_our_earth/about_freshwater/freshwater_problems/river_decline/10_rivers_risk/yangtze/yangtze_threats/