Wednesday, October 05, 2016

Should you be worried about lead and asbestos in your drinking water?

This is a follow-up from my earlier post - Ok, water from the water treatment plant is clean... do I still need water filters?


It has a couple of open ended remarks which I feel should be addressed. In addition, I have been queried about these same points by my students.


Lead
Nasty substance to consume. Well known for its neutrotoxicity, it causes mental retardation. Children are especially vulnerable, leading to learning difficulties and delays in development. Being a systemic poison, it can also lead to high blood pressure and kidney damage. Unlike many other elements, lead has no useful purpose in the human body.


Is it in our water or not?
Bear in mind that I am speaking about Singapore tap water here. Apparently, this issue has been brought up before to PUB, especially after the lead in water scare in Hong Kong in 2014.


http://www.straitstimes.com/singapore/askst-could-tap-water-to-homes-be-contaminated-by-heavy-metals-from-the-pipes (Jul 2016)


http://www.channelnewsasia.com/news/singapore/no-lead-contamination/1991828.html (Jul 2015)


In a nutshell, the articles tell us not to be worried about lead in tap water here because
  1. Our local regulations state that “Lead or lead alloy, and water fittings made of lead or lead alloy, including soldering joints with lead content are not allowed for use in potable water supply systems in Singapore,”
  2. Extensive monitoring and sampling are done on water in various stages of its treatment and conveyance, all the way to the tap end in the consumer's premises. No lead has been detected so far.
  3. Older pipes (which MAY have lead) are continually and systematically being replaced with the current safe ones.
My thoughts
  1. Unless you happen to live in a really old building which still retains its leaded pipes over the decades... and unless somehow your building falls under the radar of the extensive sampling and monitoring programme... then maybe you should be worried.
  2. Nevertheless, I still prefer to see more transparency on the sampling and monitoring programme e.g. where and when do sampling and monitoring take place. How often are they done? Better still, more water quality data should be available to the public. A once-a-year report that averages the values for the 100+ water quality parameters seems too superficial.
Image result for Lead in pipes
Figure: lead and copper pipes


Asbestos
This was formerly used in cement piping for reinforcement. Over time, as the cement pipe undergoes wear and tear, the asbestos fibres can end up in the water. Though inhalation of asbestos is the most common route of entry, evidence suggests that cancers in the esophagus, larynx, oral cavity, stomach, colon and kidney may be caused by ingesting asbestos.


First, it seems that WHO is not convinced that ingesting asbestos in drinking water poses any hazard to health. Hence, there is no WHO guideline value for asbestos in drinking water.


See: http://www.who.int/water_sanitation_health/dwq/asbestos.pdf


And in case you are still worried, good news here!


See: http://news.asiaone.com/news/singapore/water-tight-singapore-plugs-leaks-cut-wastage


In 2008, there was a major exercise by PUB to replace 120km of Asbestos-Cement Lined pipes to Ductile Iron pipes with cement lining. It seems the only pipes we have under PUB jurisdiction are either ductile iron with cement lining, stainless steel or copper.


Since asbestos cement (AC) pipes are typically only used by PUB for its major pipes, even your old building should not have them.


Image result for asbestos cement pipe
Figure: AC pipes


Hope the above are helpful to you in assessing your risks and assuaging your fears. Good luck!

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