The lack of a protective layer in the iron
pipes can cause a similar oxidation reaction to the one occurring in the lead pipes:
Fe (s) ➔ Fe2+ (aq) + 2 e–
The aqueous iron ions can cause the
water to turn an unsightly rust color, but
it can also have another troublesome side
effect. This time, elemental chlorine (Cl2)
can be reduced to chloride ions (Cl–).
When the electrons are given up by the
iron and picked up by the chlorine molecules, the following reduction reaction
occurs:
2 e– + Cl2 (aq) ➔ 2 Cl– (aq)
The loss of elemental chlorine is a
potentially huge problem for public health.
Chlorine is added to the water supply
to eliminate waterborne pathogens. The
removal of elemental chlorine via reduction can mean that waterborne pathogens
have a better chance of surviving, causing
disease.
How is Flint’s water now?
In October 2015, Flint switched back
to the Detroit system as the source of its
water. But this incident will still have some
far-reaching consequences.
At the top of the list are the potential
ongoing health problems for an estimated
6,000 to 12,000 children. Nobody can
predict what those problems may be, but
high levels of lead exposure have been
linked to developmental and behavioral
problems in children and issues related to
brain function. It will likely be a long time
before all of the problems come to light,
all of the families affected.
In addition to the long-term health
concerns, a number of lawsuits have been
filed against Flint and Michigan officials,
and millions of dollars will be required to
address the crisis and rebuild the water-pipe system. In January 2016, the U.S.
government pledged $80 million in aid to
the state of Michigan, most of which is
to be used to repair the infrastructure of
Flint’s water-supply system. In February
of the same year, the U.S. Department of
Health and Human Services announced
that $500,000 would be made available to
two Flint-area health centers to help fight
the problems caused by the tainted water.
Through knowledge of chemistry,
including the formation of precipitates, the
pH scale, and redox chemistry, scientists
were able to solve the Flint water mystery.
The crisis was stopped before it became
worse, and Flint’s water supply was made
safer—all thanks to chemistry.
SELECTED REFERENCES
How Lead Ended Up in Flint’s Tap Water. Chem.
Eng. News, 94 ( 7), Feb 11, 2016, pp 26–29.
Haines, G. K. Is this Water Recycled Sewage?
ChemMatters, Feb 2011, pp 8–10.
Walters, L. A. Flint Water Study Updates.
Virginia Polytechnic Institute and State
University: http://flintwaterstudy.org/
[accessed Sept 2016].
Dennis, B. Water in Flint Is Improving but
Still Unsafe to Drink, Researchers Say. The
Washington Post, April 12, 2016: http://
tinyurl.com/zdn3o2a [accessed Sept 2016].
Adrian Dingle is a science writer who lives
in Atlanta, Ga. This is his first article in
ChemMatters.
March 2016: The Flint
water task force, appointed
by Governor Snyder, finds
that state agencies within
Michigan are mainly
responsible for the crisis.
The Flint water crisis may be the most serious lead contamination in
drinking water to date, but other water supplies across the United States have been
affected, too. In 2001, Washington, D.C.,
changed how it treated drinking water,
and lead levels rose dramatically. In 2006,
unsafe levels of lead were found in Durham
and Greenville, N.C. In the summer of
2015, officials discovered significant lead
contamination in the drinking water in
Jackson, Miss., but waited six months before
informing residents. The list goes on.
The U.S. Congress banned the use of
lead water pipes 30 years ago, but the rule
applies only to new water pipes. Millions
of older ones remain in use. One possible
solution is to dig up and replace these lead
pipes, as has occurred between 2001 and
2011 in Madison, Wis. But doing so is
costly, and not all cities have the financial
means to do it. Other solutions include
adding more or different chemicals to the
source water and to continuously test for
contaminants. The problem is not easy to
solve, but at least the Flint water crisis has
raised awareness of the issue, and it may
lead to safer drinking water throughout
the United States in the future.
—Adrian Dingle
January 2016:
Volunteers from around the
country, including students
from Harper Woods High
School, Harper Woods,
Mich. (also pictured
on the cover), donate
water and supplies to
Flint residents.
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