Dr. Lambrinidou Ten Myths About Lead: Below 15 ppt is NOT SAFE

Myth 1: Tap water that tests below 15 parts per billion (ppb) lead is safe for drinking and cooking. 
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Fifteen ppb lead is a technical threshold that was developed and adopted to act as a trigger for water utility compliance with regulatory requirements (Pupovac 2016). It was not meant as a health-based standard. In infants, for example, lead-in-water levels below 15 ppb have been predicted to raise blood lead levels in at least a small percentage of the exposed population (Triantafyllidou, Gallagher, & Edwards 2014). For lead in drinking water, the health-based goal set by the US Environmental Protection Agency (EPA) is zero ppb (EPA 2017), and the recommended healthprotective standard set by the American Academy of Pediatrics (AAP) for lead in water in schools is 1 ppb (AAP 2016). 

It is also important to note that lead levels in drinking water tend to fluctuate. Any lead-bearing plumbing component can release dramatically different concentrations of lead at different times and under different conditions. According to a recent study, “To adequately characterize whether water in a given home with lead plumbing is truly safe, a very high number of samples would have to be collected under a range of flow conditions” (Masters et al. 2016:13). Standard lead-in-water testing, however, involves one or, at most, two samples from a tap, and routinely misses worst-case lead levels. It is, therefore, possible that a drinking water outlet measuring below 15 ppb one time will dispense lead in the hundreds and thousands ppb at other times (Triantafyllidou & Edwards 2012). 

For these two reasons – the toxicity of even low levels of lead in water and the fact that our testing methods are not designed to capture worst-case lead in drinking water – a tap measurement below 15 ppb does not signify that the water is safe for drinking or cooking. Yet the 15 ppb myth is perpetuated even by leading public health institutions like the US Centers for Disease Control and Prevention (CDC).

Myth 2: Tap water that meets federal lead-in-water requirements is safe for drinking and cooking. 

In the US, federal lead-in-water requirements are embodied in the EPA regulation called the Lead and Copper Rule. For a city’s tap water to meet Lead and Copper Rule requirements, water utilities must take one sample from one tap at a small number of “high-risk” homes known to have either a lead service line (i.e., the pipe that connects a house to the water main under the street) or other lead-bearing plumbing prone to leach lead.

For many major metropolitan utilities, for example, the minimum number of tap samples required from the entire system is as low as 50. If 90% or more of the samples collected measure below 15 ppb, the utility is LEAD Action News Volume 18 Number 2 October 2017 Page 9 of 43 deemed “in compliance” with the Lead and Copper Rule. Lead and Copper Rule compliance allows for up to 10% of taps to dispense any concentration of lead whatsoever. For example, in the latest Lead and Copper Rule test results it made public (July-Dec 2015), the Washington DC water utility took one sample from one tap at 110 homes and achieved regulatory compliance with the following results: 59 homes measured at 0 ppb; 50 homes measured between 1-8 ppb; and 1 home measured at 1,269 ppb.

In other words, even when water utilities comply with the Lead and Copper Rule, the consumers they serve can experience both chronic and acute exposures to lead, without triggering a regulatory violation. Despite this fact, the EPA allows water utilities to declare their water “safe” for drinking and cooking, simply because they meet regulatory requirements (Q&A session, EPA Lead and Copper Rule stakeholder workshop, Washington DC, October 14-15, 2008).

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