90%’ile = 3.9 ppb in Flint Tier 1 homes.
Dr. Susan Masten (Michigan State University) has published results of independent testing in Flint, MI for a 7-month period starting August 28 2017. The 90%’ile lead is 3.9 ppb, for Tier 1 homes, completely consistent with official LCR data from the State of Michigan and our own Flintwaterstudy citizen science sampling in 2017-2018. Read her report below:
It’s great to see such low results. I have one question. In the table, when “service line material” is reported as “Lead-copper” or “lead-galvanized” what exactly does that mean?
Len,
Where the service line materials are reported as X-Y, X is the material on the public side, Y is the material on the private side.
Susan Masten
Dear Dr. Masten:
The 1 liter first draw will likely determine the effect of lead-containing brass plumbing fixtures and lead-soldered plumbing on the lead concentration of 6 hour resident water in such lines. However the 1 liter ‘first draw’ will not likely reflect water that has been resident for 6 hours or more in the actual lead service line upstream from home water meters.
A typical home residential plumbing system cold water line after the water meter will have a volume greater than 1 liter up to the water meter, and the first draw sample will not reach or reflect incoming water that has been fully resident in a 100% lead service line and upstream of the meter.
I don’t know if or how Flint Water Study confronted this issue, but I’d urge that you select some homes for a special study, calculate the total volume of the cold water line from meter to the faucet used for sampling, first draw the first 1 liter and test and then draw the calculated remaining volume of water so as to bring to the tap a verified-by-volume-previous-drawn sample of water resident in confirmed lead service lines to sample and test that service-line-6-hour-resident water to compare with the first liter drawn….and publish the results for a some portion of your sampling site efforts.
regards, Alex Sagady
Alex, I don’t disagree that your proposed study would yield useful results, however, the terms of the settlement were simply to test lead in accordance with the LCR. As such, that is all we are funded to do.
Thank you, I appreciate the feedback. I retired from a utility that had roughly 20,000 lead public services, yet, it was uncommon to find a lead private service. I may be reading too much into your data, but it appears that private lead services are also relatively rare in Flint. With all the publicity on Flint, I don’t believe that point has ever come up before.
On somewhat of a different topic, do you have any plans (funding) to collect sequential samples at some of these locations? I think it would be interesting, as well as reassuring for residents, to measure the lead concentration in water that has actually sat in a lead pipe.
Thank you and good luck with your research.
Len
A serious problem with these results is lead leaching from LSL is known to be higher in the summer. See page 6 at https://archive.epa.gov/region03/dclead/web/pdf/tewg121611.pdf
These sample dates are from the cooler time of the year.
https://pubs.acs.org/doi/10.1021/acs.est.5b05060#/doi/10.1021/acs.est.5b05060
Seasonal Variations in Lead Release to Potable Water
Sheldon Masters*†, Gregory J. Welter‡ and Marc Edwards†
The first 6-month sampling effort began in late August. The second 6-month sampling effort should begin soon and will include the summer months.
Len, based on the data I have for Flint, lead service lines on the private side are quite rare.
Unfortunately, at this point, I do not have funding to collect sequential samples in homes.
Susan, I hope more funding is in your future.
Thank you for the feedback!
Len Schantz
So would you say the public water supply now appears to be safe to drink for all children in Flint?
That was not in my scope of work. As mentioned above, my contract is to do two rounds of testing in accordance with the LCR. The report documents our findings.
We remind everyone there is no such thing as perfectly safe water. Even bottled water has health risks. On a relative basis, there is no reason to believe that present day unfiltered Flint water, currently has a greater health risk than water in other cities with old pipes. Proper use of filters to treat water used for cooking or drinking, would virtually eliminate the water lead risk, but use of the filters is voluntary and a personal decision. It is our position that drinking water passing through lead service line pipes, in any city, has health risks. We would recommend use of the lead filters if you live in a home with a lead pipe, and as long as the State is providing the lead filters free of charge, we would recommend use of the lead filters to treat water used for cooking or drinking in all Flint homes.
On the testing of water in lead pipe issue, our data based on second draw lead service line (LSL) sampling of Flint water, that lead levels are very much improved. Second draw is a good, but imperfect, way of tracking LSL lead. Obviously profile or sequential sampling is best, but for consumer sampling, second draw is an accepted approach: https://flintwaterstudy.org/2017/09/flint-water-study-press-conference-09-15-2017/
– Dr. Edwards
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