The water crisis of Flint, Michigan has brought the issue of lead in drinking water back into the public eye. While the overall health implications of the crisis are yet to be seen, recent research published in Lancet Public Health by Dr. Bruce P. Lanphear of Simon Fraser University has shed light on the health risk associated with lead exposure. The study attributed approximately 400,000 deaths annually in the USA alone to lead exposure. Most deaths are associated with cardiovascular disease and ischaemic heart disease. Dr. Lanphear’s estimate was approximately 10 times greater than the previous one. The primary difference is the inclusion of all-cause mortality, cardiovascular disease mortality, and ischaemic heart disease mortality at Blood Lead Levels (BLL) less than 5 µg/dL, the current Centers for Disease Control and Prevention (CDC) acceptable BLL for adults. The CDC has noted that there is no safe BLL identified for children. This highlights the importance of preventing lead crises, like Flint, Michigan (2014-present) and Washington, DC (2001-2004), where residents were exposed to high levels of lead, but also minimizing chronic exposure to all levels of lead. The study did have a key limitation: single baseline BBLs from participants of the Third National Health and Nutrition Examination Survey, conducted between 1988 and 1994, were used to determine cumulative lead exposure. Participants were then followed up on in 2011. Ultimately, the impact of lead in our environment is undeniable.
Lead enters drinking water through the corrosion of lead or lead-containing (ie. brass) pipe, fittings, fixtures, solder and flux occurring in the service line (between the water main and the building) and premise plumbing. Corrosion can be encouraged when changes are made to upstream processes such as changing water sources (Flint, Michigan) or disinfectants (Washington, DC). Corrosion control is typically accomplished by adding a corrosion inhibitor, such as polyphosphate, which forms a protective scale on the inside of pipes. Changes in water quality can destabilize the protective scale resulting in it breaking down and increasing corrosion rates. Another key component of lead release is the biofilm which forms on pipe walls. Biofilms can act as both a source and a sink for lead. Microorganisms produce exopolymeric substances (EPS) which allow them to stick to surfaces and form biofilms. EPS acts as a sink by adsorbing lead to its surface, removing it from the bulk water. However, the EPS can dislodge from the pipe and become a source of lead. It is important to note that while polyphosphate is an effective corrosion inhibitor, it is also a nutrient for microorganisms. Therefore, it is important that corrosion and microbial growth are both monitored and managed effectively. Microbial growth can be monitored using a variety of tools including LuminUltra’s 2nd Generation ATP, which provides a rapid, field-based test for both planktonic microorganisms and biofilms.
If you are concerned about lead in your home’s drinking water, there are a few steps you can take:
- Call your municipality or local water utility and inquire about whether lead is an issue of concern in your community.
- If water hasn’t been used for a few hours, such as overnight or after returning from work, flush the plumbing by running cold water through your tap for a few minutes. Lead is most likely to occur in stagnant water.
- Use the cold water tap for drinking and food preparation.
- Use an NSF International approved treatment device in your home. Not all water filters are able to remove lead, so make sure yours is approved for lead removal and that you are following the manufacturers’ maintenance instructions.