20 Days of H20

I was excited to discover #20daysofH20 this afternoon.  It is a great way for Water Canary to educate people about water quality.

So each day, for the next 20 days, we’ll be writing a post about a different contaminant.

Today we start with Lead (Pb).

In even small concentrations, lead consumed through drinking water can cause serious health problems.  It is a substance that the WHO concludes “has no known biological benefit to humans.”  Today there is widespread consensus about its dangers.  For instance, in the US if even 15 parts per billion are detected in drinking water, that is enough to trigger a response by the Environmental Protection Agency.

History:

Up until fairly recently lead was the most commonly used material in water pipes – a practice that goes back all the way to Roman times.  One reason for this is that lead is incredibly abundant in nature and far easier to extract than many other metals – but the primary reason is that lead is far easier to work with.  It has a low melting temperature (327.5 °C / 621.5 °F) which makes it more pliable and easier to cast.

By the 1850’s there was enough scientific evidence to link lead pipes to severe health problems, however it took nearly a century for lead to be phased out completely.  According to the NIH, by 1900 over 70% of US cities with populations over 30,000 used lead pipes in their water lines.  This trend began to reverse in the 1930’s as evidence mounted that trace amounts of lead in water posed a serious public health problem, but it was not until the 1960’s when the Safe Drinking Water Act was passed that use of lead pipes was outlawed.

Further reading:

http://www.who.int/water_sanitation_health/diseases/lead/en/
http://www.freedrinkingwater.com/water-contamination/lead-contaminants-removal-water.htm
http://en.wikipedia.org/wiki/Water_pipe#History
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2509614/
http://www.lenntech.com/periodic/water/lead/lead-and-water.htm

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