It is common knowledge that the Romans made water piping and drinking vessels from lead 2,000 years ago. There are anecdotes that use of lead may have caused the fall of the Roman Empire. Whether or not those anecdotes are true, the fact remains that lead poisoning is real threat to human health. It is interesting that it has taken us 2,000 years to pass laws to prohibit the use of lead in materials that we use in our daily lives. Lead pipes were so common in 20th century plumbing that they were incorporated as a murder weapon in the popular family game Clue which was released in 1949.
I think we are all aware of activities and substances that are not good for our health. As humans, we have a habit of giving into our baser impulses. Having the right to make bad decisions is sometimes known as “adulting.” What makes lead poisoning so harmful is that it affects the youngest and most innocent among us. Infants and young children are particularly vulnerable, with one of the worst effects of lead poisoning being irreversible brain damage. Unborn children are the most at risk of suffering from high levels of lead.
Lead is a chemical element with the symbol Pb, which stands for “plumbum” in Latin. In ancient times, plumbers used lead to make pipes because it was easy to work with and was relatively stable. It has a low melting point, high density and is very ductile, which means it can be formed easily into different shapes. From an engineering standpoint, one can see how it would be advantageous to design and manufacture items with such a versatile element. The modulus of elasticity, l, for lead is about eight times less than that of copper, making it much easier to work with. This explains why plumbers from ancient times could roll a sheet of lead into a pipe shape and solder the seam together.
Not to mention that the melting point of lead is much lower than other common metals used in manufacturing, being about three times less than copper. This aids in the smelting process, where the element of interest is isolated and other materials are separated out.
Our collective history in engineering has many examples of ideas that seemed good at the time and ended up having undesirable side effects. One example from medicine that goes back to the age of lead piping is the use of leeches for bloodletting. While this seems like a bad idea, my research has shown that leeches are still used today in modern medicine. It turns out that leeches can repair microscopic blood vessels that are difficult to repair with other means.
A different type of “leeching” that is similar but spelled differently is “leaching.” We should be aware of water as a solvent, something that has the ability to dissolve other solids. When we design laboratory systems with pure water, this is one of the reasons we use non-ferrous piping.
One of the reasons lead is dangerous to humans is that it is a neurotoxin. Neurotoxins are substances that damage brain cells or nerves. Because lead has the potential to harm so many innocent people, we have passed laws to over the years to limit the use of lead. Lead-based paint for homes was banned in 1978; lead piping was banned in 1986 (but allowed to remain if already installed).
As plumbing engineers, we are all too familiar with protecting public health. We work tirelessly to ensure the public is not harmed by cross-contamination through backflow prevention and health is not compromised by waterborne pathogens by implementing best design practices and keeping abreast of new technologies. Even with our best intentions, we find ourselves battling a legacy of misunderstanding that has compromised some of our watersheds.
There are tasks for us to help improve aging infrastructure. Many of us work on buildings that involve the abatement of other dangerous materials such as asbestos. With lead, the biggest danger to workers is dust, and the EPA recommends certain methods of keeping dust to a minimum during demolition.
In a sense, the next millennial may be known as the era “after lead pipe.” The optimist in me knows that we will discover more ways to live better lives, continuing to identify practices that affect public health and safety. Hopefully we all “get a clue” and figure out ways to share them with one another. It is kind of ironic that it took 2,000 years to stop making plumbing piping out of a material that was poisonous to the human body; one of the biggest ironies is that the lead pipe game piece in Clue was made of lead itself.