Many of us use tap water all the time.
We drink it, cook with it, use it to make baby formula.
用来饮用 炒菜 制作婴儿食物
We trust our tap water.
But you won’t find that trust in Flint Michigan,
because failure at every level of government
allowed lead, a toxic metal,into the water supply.
But concerned citizens and scientists
were able to turn the chemistry to bring the truth to light
to better protect their water, and hopefully, taps across the country.
When Flint started getting its water from the Flint River in 2014,
city officials could have tailored the chemistry of that water
to prevent it from becoming a problem.
We won’t get into all those details here,
but you can read about them in Michael Torrice’s in-depth report for C&EN.
Here’s a link to that.
Without corrosion-limiting chemicals like orthophosphate
Flint’s plumbing lost a protective mineral layer that naturally builds up in its pipes.
Once that was gone, the water began attacking the pipes themselves,
some of which contained lead or were just made of lead.
The U.S. stopped using lead in plumbing decades ago,
but we never got rid of the old stuff.
How much lead plumbing is out there?
We asked Marc Edwards,
one of the key figures in uncovering the Flint water crisis,
at a recent press conference.
Marc: Anywhere from 3 to 13 million lead pipes.
And you know that’s obviously a wide range.
But no one knows. No one knows the number.
Most people don’t even know
if they have a lead pipe in front of their house,
because,frankly, the water utility doesn’t know.
We don’t know where these lead pipes are.
And now people feel that
as long as those lead pipes are there,
and they’re right, it’s a ticking time bomb.
Matt: That bomb went off in Flint.
Here’s Jeff Parks, a research scientist in Marc Edwards’ group,
telling us what the team found in one sample
of Flint resident Lee-Anne Walters’ home.
Jeff: One of her samples was over 13,000 ppb.
Matt: That’s 13,000 parts per billion,
which would be 13 mg of lead in 1 liter of water.
The Environmental Protection Agency and the Centers for Disease Control
both say that no level of lead is safe for children.
But EPA also has a so-called action level for lead at 15 ppb.
That’s nearly one one-thousandth of what Jeff found in Lee-Anne’s home.
We recently visited Jeff to learn how the team measured lead in Flint’s water.
Here he is with water from Lee-Anne’s house.
That rust color you see actually comes from iron pipes.
Lead is a lot tougher to detect with your eyes.
That’s why Jeff uses an instrument called
an inductively coupled plasma mass spectrometer, or ICP-MS.
The machine sucks up a bit of water and
spritzes it into a chamber with a plasma.
It rips electrons away from atoms within the sample.
The ionized atoms are then separated by
what’s called a quadrupole mass spectrometer
that generates an electric field to sort atoms
by how massive they are relative to their charge.
Jeff finds lead by looking for one of its signature isotopes,
but he usually sees lead at levels much lower than 13,000 parts per billion.
Jeff: I don’t calibrate the instrument that high
because we don’t see lead that high.
I talked to Marc about it and he said,
“Well, dilute the sample and run it again
to see is it really that high or has something happened to your instrument.”
We took 1 ml of her sample
and put 99 ml of distilled water
and ran it again and we got 130.
So it was 13,000.
Matt: Jeff used the ICP-MS to analyze more than 270 Flint water samples last fall.
Although Lee-Anne’s house was the worst he saw,
Jeff still found that about 10% of the water samples he tested
had 27 ppb lead or higher.
That’s roughly twice the EPA action level.
But action level doesn’t mean what you probably think it does.
The action level comes from what’s called the Lead and Copper Rule,
which Jeff calls “weirdly worded.”
Marc has some stronger opinions.
Marc: The Lead and Copper Rule is a lousy law to start with.
So even if you’re meeting the law,
you get many homes that have over 150 even 1,000 parts per billion lead.
That’s not illegal in existing law.
You can have hazardous waste levels of lead
coming out of a kindergarten classroom in this country.
There’s no law. People don’t realize.
There’s no maximum amount of lead law
that applies to any tap in the United States anywhere.
Matt: A water system meets the Lead and Copper Rule
when at least 90% of the households it serves
have lead levels below the action level.
But that’s kind of like saying a city is not on fire,
even when 10% of its buildings are burning.
So it’s a pretty lenient rule and Flint still broke it.
所以说 这是相当宽松的标准 而弗林特市没能遵守
But so have other cities in the past, including our nation’s capital.
Marc’s hoping for stricter laws in the future,
but it’s up to legislators and regulators
to change the rules designed to protect the nation’s drinking water.
Meanwhile, Virginia Tech researchers and EPA are now helping Flint residents
re-test the same Flint homes Jeff and the team examined last fall.
Both Marc and Jeff believe they’re going to see much lower lead levels
because the city switched back to less corrosive water
and because Flint’s doing a much better job of controlling water chemistry.
The new data will be posted at flintwaterstudy.org soon,
so be sure to keep an eye on that.
The water should get better,
but there are things that cannot be repaired.
One Flint doctor estimates that as many as 8,000 children
were exposed to lead during this disaster.
And remember, America’s official stance
is that no amount of lead is safe for kids.
Something like that makes it hard for people
to believe in the safety of their tap water.
Marc: Once you’ve been betrayed in this way,
you might never get those people to trust water again.
And who can blame them?
Many of us use tap water all the time.