Get the Lead Out
Before Flint, there was Washington, DC. Likely the DC incident is not fresh in people’s minds. Similar circumstances to those in Flint, MI resulted in elevated lead concentrations in water coming out of the tap in Washington DC about 13 years ago. As a result of our aging infrastructure and the complexity of the issue, we will likely find (if we look) many other instances of lead in drinking water above regulatory standards even after Flint is a distant memory. While drinking water and wastewater may be considered as two very separate issues in your mind, to the general public they are related. And in fact, the pipes can cross. So, read this library and get some fluency in the related issues of lead in drinking water and our aging infrastructure.
The first article in the library is all about how different types of pipes and different types of water disinfectants can react to solubilize lead. The article refers to the EPA Lead and Copper rule- https://en.wikipedia.org/wiki/Lead_and_Copper_Rule. This rule is critical here as it set standards for Pb and Cu concentrations in drinking water as well as for the corrosivity of the transmission pipes. In general, and according to Wikipedia, the rule has been successful with reductions in both Cu and Pb in the majority of the waters sampled. Would that it were so simple….
Our water gets treated with disinfectants to make sure that we don’t get sick from drinking it. The standard disinfectant for many years was chlorine. That kept the microbes at bay and also resulted in minimal dissolution of Pb from pipes. However, concerns that chlorine in the water resulted in the formation of potential carcinogens resulted in the search for alternatives. One of the primary alternatives chosen was chloramine: great for the pathogens, not so good for the Pb. The problem in both Washington DC and Flint MI was not with the water going into the pipes- it was with the Pb that was solubilized when the agencies altered the chemistry of the water by changing from chlorine to chloramine. The first paper goes into detail on the types of pipes and the reactions that water treated with either chlorine or chloramine will have and the relative amount of Pb that ends up in the water as a result. This discussion is further complicated by the fact that our pipes are not all the same. New lead pipes will behave differently than old ones. Brass pipes actually contain % concentrations of Pb. The solder used in many cases was Pb based, and then too there are many miles of old Pb based pipes remaining in most cities. There are further complications. The amount of time that the water sits in the pipe can influence the amount of lead that comes into solution. Lower retention times mean less lead. However, letting the water run for a minute- the standard solution for assuring that only the fresher and lower lead water is used is shown to be ineffective in this study. Another complicating factor is the requirement that cities maintain enough water in the pipes to be ‘fire ready’- great for when your house is burning, but not good at all if you are concerned about solubilizing lead. Final complications include the pH and nitrogen concentrations in the water. Higher N concentrations mean more Pb is in solution. The good news here is that adding P with the chloramine typically reduces the potential for Pb to come into solution and into the water.
The next two articles go into detail about how Pb in the water impacts blood Pb in the kids. The first article is about the blood lead increase in Washington, DC. Here childrens’ blood Pb levels increased over the period when Pb in water was high. The increase was not apparent when the city as a whole was sampled. However, the neighborhood by neighborhood sampling told a different story. Children in higher risk neighborhoods showed more significant increases in blood Pb than in lower risk communities. The ‘at risk’ communities had higher numbers of lead pipe than the low risk areas. About 6% of the kids in these areas had elevated blood Pb, compared with just under 2% nationwide. In the high- risk neighborhoods, the increase was 0- 6% over the mean. Note that Marc Edwards is an author on many of the papers in this month’s library. He is a professor at Virginia Tech and is the source on this topic.
The third paper is the same topic, same scenario, but the one that has been making the National news. Kids in Flint were sampled for blood Pb with levels prior to the switch in water used as a basis for comparison. The increase in kids with elevated blood Pb (2.4-4.9%) was similar to DC and again, increases were more common in disadvantaged neighborhoods with a greater fraction of Pb pipe.
The purpose of the 4th paper is to help you realize that this concern is not limited to faraway places like DC and Flint. Here authors worked with 63 elementary schools in Seattle and 601 elementary schools in LA to sample lead in water and use the data to predict the percentage of kids with elevated blood Pb. As part of this work, the schools then remediated the infrastructure to reduce the Pb in the water.
The infrastructure is the key to all of this. The last paper is actually a book. The National Academy of Science regularly tackles timely issues and often their reports are published as books. These all are free to download (http://www.nap.edu/). In 2006 the National Academy published a study on our drinking water distribution system focusing on understanding and reducing risks. While Pb in drinking water has recently been making headlines, we have to recognize that we expect our drinking water to be free of many additional and also very troubling contaminants. With aging infrastructure and leaky pipes, the path to clean water is increasingly complex. And that is one way that we get the overlap. At a recent NAS conference, the potential for drinking water to be contaminated by untreated sewage through overlapping leaky pipes was brought up. This is a book to download and browse through. Something to think about as Flint moves to the back of our minds.