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.

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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:

PITCHER/POUR OVER FILTERS

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

FAUCET FILTERS

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