Lead in Drinking Water – Health Risks to Flint Residents

We have been getting a lot of questions about the health risks associated with drinking unfiltered Flint water. Aside from the obvious statement that “there is no safe level of lead exposure,” we have recent peer-reviewed research from our group that provides useful estimates.

One paper is: Triantafyllidou, S., Gallagher. D. and Edwards, M. Assessing risk with increasingly stringent public health goals: the case of water lead and blood lead in children. Journal of Water and Health. doi: 10.2166/wh.2013.067 58-68 (2014).

Based on our survey, the average lead in first draw Flint water is 10.3 ppb (this was bottle 1 in the survey), and the average lead after 45 seconds of flushing is 10.6 ppb (this was bottle 2). So let’s use the average lead exposure of 10 pbb as the baseline estimate.

According to results in Triantafyllidou et al, (2014), it is estimated that for about 25% of infants drinking formula made from tap water at 10 ppb, their blood lead would rise above the Centers for Disease Control and Prevention (CDC) level of concern of 5 micrograms/deciLiter (or ug/dL). This is why we emphasized that no one should be feeding their infants formula from unfiltered Flint tap water. The risk is very high.

Children aged 1-2 years old consume less water per unit body weight than infants. Thus, their risk is lower. However, they also tend to get some lead exposure from other sources. If we assume they get “normal lead” from dust and soil exposures, consuming unfiltered tap water at 10 ppb is predicted to raise the blood lead of 25% of the 1-2 year old children above the CDC’s level of concern (5 ug/dL). Thus, again, the risk is significant.

If you cannot afford filters or bottled water, flushing can really help. After 3 minutes flushing in Flint water, the average lead was reduced to 4 ppb (bottle 3 in our survey). Even though we consider this too high, it is still about 3 times lower than that obtained from the first 1 liter or after 45 seconds flushing. Thus, the risk is reduced by 3 times as well. In the case of infants using formula with this flushed water, about 5% are expected to have blood lead elevations about the CDC level of concern. Since we consider this risk too high for our kids, we believe it is too high for Flint’s kids as well. It highlights our warning that nobody in Flint should be using unfiltered tap water to make up infant formula, even after flushing.

We also note that pregnant women consuming unfiltered Flint River water are also at risk. As detailed in our other peer reviewed research publications, even modest elevations in a mothers’ blood lead are hypothesized to increase the risk of miscarriages or fetal death. We retrospectively tested that hypothesis for a time period of high water lead exposure in Washington D.C.; indeed, when lead in water was high, miscarriages and fetal deaths were also high (see article here).

While we are most concerned with lead exposure to pregnant women and children under age 6, no one benefits from lead exposure, even though the health risks are lower for other groups.

Therefore, we reiterate our earlier advice to Flint consumers. Until further notice, Flint tap water should only be used for cooking or drinking if one of the following steps are implemented:

  • Treat Flint tap water with a filter certified to remove lead (look for certification by the National Sanitation Foundation (NSF) that it removed lead on the label OR see our table below), or
  • Flush your lines continuously at the kitchen tap, for 5 minutes at a high flow rate (i.e. open your faucet all the way), to clean most of the lead out of your pipes and the lead service line, before collecting a volume of water for cooking or drinking. Please note that the water needs to be flushed 5 minutes every time before collecting water for cooking or drinking. For convenience, you can store water in the refrigerator in containers, to reduce the need to wait for potable water each time you need it.

Bottled water is another option.

To help choose filters that are NSF certified for lead removal, we summarized data from NSF/ANSI 53 Certified Lead Filters below in a user friendly table:


Aquasana Inc. (http://www.aquasana.com/)
Model No. Replacement Part No. Service Cycle Before Replacement (gallons) Amazon Link
AQ-PWFS-D-B AQ-PWFS-R-D 320 Go here
AQ-PWFS-D-W AQ-PWFS-R-D 320 Go here
AQ-PWFS-P-B AQ-PWFS-R-D 320 Go here
AQ-PWFS-P-W AQ-PWFS-R-D 320 Go here
AQ-PWFS-RB-2 AQ-PWFS-R-D 320 Go here
AQ-PWFS-RB1 AQ-PWFS-R-R 320 Go here
Zero Technologies, LLC (www.zerowater.com)
Model No. Replacement Part No. Service Cycle Before Replacement (gallons)
ZD-010RP ZF-201 15
ZD-013D ZF-201 15 Go here
ZD-013W ZF-201 15 Go here
ZD-018 ZF-201 15 Go here
ZD-023-1 ZF-201 15
ZP-001 ZF-201 15
ZP-006 ZF-201 15 Go here
ZP-010 ZF-201 15 Go here
ZS-008 ZF-201 15 Go here


Culligan International Company (www.culligan.com)
Model No. Replacement Part No. Service Cycle Before Replacement (gallons)
FM-15A FM-15RA 200 Go here
FM-25 FM-25R 200 Go here
WFM-17 WFM-17R 200
Kaz Inc. (Pur) (www.purwater.com)
Model No. Replacement Part No. Service Cycle Before Replacement (gallons)
FM-9100B RF-9999 100 Go here
FM-2000B RF-3375 100 Go here
FM-3700B RF-9999 100 Go here
PFM333C PFF331C 100
FM-3333BNM RF-9999 100 Go here
FM-4000B RF-9999 100 Go here
FM-3500B RF-9999 100 Go here
FM-8100L RF-4050L 100
FM-4100B RF-9999 100 Go here
FM-3333B RF-3375 100 Go here
FM-9600B RF-9999 100 Go here
FM-9400B RF-9999 100 Go here
FM-3400B RF-9999 100 Go here
FM-3000 RF-3050 100
FM-9000B RF-9999 100 Go here
PFM370C PFF991C 100
PFM400C PFF991C 100
The Brita Products Company (www.brita.com)
Model No. Replacement Part No. Service Cycle Before Replacement (gallons)
SAFF-100 FR-200 100 Go here
FF-100 FR-200 100

Primary Author: Dr. Marc Edwards
Filters Table: Anurag Mantha

4 thoughts on “Lead in Drinking Water – Health Risks to Flint Residents

  1. I’m new to your website. Two requests since this website emphasizes the ethics of science communication:

    1. Could you provide a lay summary of how and how much lead in water does or does not make its way into blood, bone, and other tissues? For example, I understand how the conservation of mass helps us figure out that to reach a blood lead concentration of 6 micrograms per tenth of a liter (deciliter; so 60 ppb), some lead in water (say your 10 micrograms per liter, 10 ppb) must be consumed. How and why does it become concentrated?

    2. Isn’t this a situation where you could bring lead isotopes to the table to sort out the contribution of different potential lead sources to that total lead loading? Isotopes don’t lie.

    • Hi Tony,

      Here are our responses:
      1) A good resource would be a review paper by Triantafyllidou and Edwards (2012) titled “Lead (Pb) in Tap Water and in Blood: Implications for Lead Exposure in the United States”. If you’d prefer a more direct answer than a link to this paper, please let us know and we’ll respond.

      2) The isotopic fingerprint from lead plumbing is derived from an infinite number of lead sources. If it was all from lead pipe from one mine, isotopic fingerprinting would be ideal.

      However, there are three types of lead plumbing sources including solder, lead pipe and leaded brass, all of which came from different sources. For brass in particular, the lead was added to the alloy from different sources, and all would have different fingerprints. As a result, the isotopic lead fingerprint for every house is different.

      Hope this helps!

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