DANGERS
OF CHLORINATED WATER
There were just over
4 million live births in the U.S. in 1992 (4,065,000, to be exact),
according to the STATISTICAL ABSTRACT OF THE UNITED STATES 1997.[1]
In addition to these live births, there were 30,000 fetal deaths
in 1992, the most recent year for which we have data.[2] A fetal
death is one that occurs after at least 20 weeks of gestation
in the womb but prior to birth. In actuality, there were very
likely more than 30,000 fetal deaths in 1992. The STATISTICAL
ABSTRACT (table 124) says, "There is substantial evidence
that not all fetal deaths for which reporting is required are
reported." In any case, life expectancy at birth in the U.S.
in 1992 was 75.8 years,[3] so fetal deaths that year resulted
in the loss of at least 30,000 x 75.8 = 2.27 million person-years
of life. In addition, of course, many of these 30,000 fetal deaths
precipitated a personal crisis for the parents.
In addition to fetal
deaths, there are spontaneous abortions --pregnancies that terminate
spontaneously before the end of the 20th week of gestation. These
are far more common than fetal deaths, though the exact number
is not known. Various studies estimate that spontaneous abortions
occur in somewhere between 6.5% and 21% of all pregnancies.[4]
Thus in 1992, there may have been at least 265,000 to 855,000
spontaneous abortions in the U.S. Together, spontaneous abortions
and fetal deaths are termed "miscarriages." Recent studies
indicate that some miscarriages --as well as some serious birth
defects --may be caused by the chlorine added to drinking water
as a disinfectant.
In the U.S., chlorine
is added to public drinking water supplies as
a public health measure to kill harmful bacteria in the water.
The added chlorine reacts with naturally-occurring organic matter
in the raw water (chiefly humic and fulvic acids), creating a
host of chlorinated chemicals as by-products. Health agencies,
including the federal EPA [Environmental Protection Agency] simply
ignore most of these by-products and know almost nothing about
them. Instead, they focus on four by-products, allowing these
four to act as surrogates for all the others. The four that EPA
pays attention to are chloroform, bromoform, bromodichloromethane,
and chlorodibromomethane. Together, these four are called "trihalomethanes"
or THMs. According to federal drinking water regulations, if a
public water supply serving over 10,000 people contains more than
100 parts per billion (ppb) of total trihalomethanes, the water
is unacceptable. However, since there are usually no other available
sources of drinking water, EPA is usually not in a position to
do anything except urge the water supplier to try to clean up
its act. A study
by the California Department of Health published in March, 1998,
tracked the drinking water consumption and the pregnancy outcomes
of 5144 pregnant women in a prepaid health plan during the period
1989-1991.[5] This was a prospective study --the drinking water
consumption of the women was ascertained as soon as their pregnancy
was registered in the study's database. Later, the outcome of
their pregnancy was compared with the amount of water they drank
and the total amount of trihalomethanes they received by drinking
water (information received from the water companies). The study
found that 16% of women drinking 5 or more glasses of water per
day containing more than 75 ppb THMs had miscarriages, whereas
only 9.5% of women drinking less water, or water lower in THMs,
had miscarriages. Thus among women with high exposure to THMs
in drinking water, the likelihood of spontaneous abortion was
1.8 times as great as it was among women with low exposure. Furthermore,
spontaneous abortion occurred, on average, a week earlier among
women with high exposure (10.2 vs. 11.2 weeks of gestation). The
strength of this study was its prospective nature; it did not
rely on women to remember how much water they drank in the past.
To see if their results represented a real effect, the researchers
compared women who filtered their water, or who let the water
stand before drinking it, with women who drank it straight from
the tap. (THMs are volatile and will slowly leave water that is
allowed to stand.) The results were consistent with THMs causing
spontaneous abortion.
In January of this
year, the Agency for Toxic Substances and Disease Registry published
a case-control study showing that serious birth defects --spina
bifida, or neural tube defects--are associated with total trihalomethanes
ingested in drinking water.[6] Neural tube defects are serious
birth defects in which the spinal cord is not properly enclosed
by bone.
This statewide study
in New Jersey found a doubled risk of neural tube defects among
those with the highest exposures to THMs in drinking water. This
study pointed out that exposure to THMs can also occur through
the contamination of indoor air. Flushing toilets, showering,
and washing dishes and clothes, can inject THMs into household
air, exposing residents.
A previous study of
75 New Jersey towns by Frank Bove had examined 80,938 live births
and 594 fetal deaths that occurred during the period 1985-1988.
This study examined public water company records and compared
pregnancy outcomes to the amounts of THMs delivered to the home
in drinking water. It did not examine the amount of water ingested.
The study found no relationship to fetal deaths, but the likelihood
of neural tube defects was tripled by exposure to THMs at levels
exceeding 80 parts per billion.
This study provoked
a letter to the editor of the AMERICAN JOURNAL OF EPIDEMIOLOGY,[8]
in which the authors suggested a biological mechanism by which
trihalomethanes might cause neural tube defects. Neural tube defects
are known to be associated with vitamin B12 deficiency and the
letter pointed to studies showing that vitamin B12 use by the
body can be disrupted by chloroform, one of the four main trihalomethanes
in chlorinated drinking water.
An even earlier case-control
study reported on pregnancy outcomes among women who delivered
babies at Brigham and Women's Hospital in Boston during the years
1977-1980. Indicators of water quality were taken from public
water supply companies. No data were available on the amount of
water ingested. The water quality indicators were compared among
1039 cases of babies born with birth defects, 77 stillbirths,
and 55 neonatal deaths (babies that died within a week of birth)
vs. 1177 controls. Stillbirths were 2.6 times as common among
women exposed to chlorinated surface water, compared to controls
whose water was disinfected with chloramine instead of chlorine.[9]
More recently, a study
of drinking water and pregnancy outcomes in central North Carolina
reported a 2.8-fold increased likelihood of miscarriage among
women in the highest exposure group for trihalomethanes in drinking
water.[10]
Very recently, a second
study from the California Department of Health has shown that,
in one area of California, women who drank cold tap water had
nearly a five-fold increased risk of miscarriage, compared to
women who drank mostly bottled water very low in trihalomethanes.[11]
Bottled water is often disinfected by a process called ozonation
instead of chlorination. Bubbling ozone through water kills bacteria
effectively, avoids the distinctive taste and odor of chlorine
in the treated water, and produces no dangerous trihalomethanes.
Many people buy bottled water simply to avoid the taste of chlorine.
U.S. EPA is currently setting new standards for trihalomethanes
in drinking water. The new regulations would apply to all water
companies, not just those serving 10,000 people or more, and they
would limit total THMs to 80 ppb, down from the present 100 ppb.[12]
Still, since several studies link trihalomethanes at 75 ppb or
even less to increased miscarriages, EPA's new standard seems
dubious even before it has been established.
American water suppliers
seem stuck on chlorination as the best way to disinfect drinking
water. However, many European cities, and some Canadian cities,
such as Ottawa, have long ago turned away from chlorination in
favor of ozonation to disinfect their water. In recent years,
a few smaller American cities have begun to use ozonation: Emporia,
Kansas and Littleton, Massachusetts, for example. The Santa Clara
Valley Water District in California has announced that it is switching
to ozonation over the next 5 to 8 years, as has the city of Las
Vegas, Nevada.
Still the vast majority
of water supplies in the U.S. remain chlorinated. And water quality
experts remain in the dark about trihalomethane levels in water
delivered to customers. Kellyn S. Betts, writing in ENVIRONMENTAL
SCIENCE & TECHNOLOGY quotes the EPA official in charge of
the new THM regulations saying no one knows how many U.S. water
systems deliver water with THMs exceeding 75 ppb.[12] Betts says
the American Waterworks Association confirmed for her the absence
of data on THM levels in U.S. drinking water systems. The current
reporting system only keeps track of water systems that exceed
100 ppb as an annual average. Erik Olson, a water quality expert
with the Natural ResourcesDefense Council (NRDC), an environmental
group in New York City, points out that THM levels in water supplies
typically increase by as much as a factor of 1.5 to 2 during the
summer months. And he says short-term exposures may be very important
in producing some of the pregnancy outcomes reviewed here --spontaneous
abortions, fetal deaths, and serious birth defects. "We may
be totally overlooking the risk of short-term exposure,"
Olson said.[12]--Peter Montague (National Writers Union, UAW Local
1981/AFL-CIO)
===============
[1]
STATISTICAL ABSTRACT OF THE UNITED STATES 1997 [117th edition]
(Washington, D.C.: U.S. Government Printing Office, October, 1997).
See Table 88.
[2] The
STATISTICAL ABSTRACT for 1997, cited above, Table 123, says there
were 7.4 fetal deaths per 1000 live births in 1992, so the total
number of fetal deaths that year was 7.4 * 4,065 = 30,000.
[3] STATISTICAL
ABSTRACT for 1997, cited above, table 117.
[4] S. Hamamah
and others, "The effect of male factors in repeated spontaneous
abortion: lessons from in-vitro fertilization and intracytoplasmic
sperm injection," HUMAN< REPRODUCTION UPDATE Vol. 3, No.
4 (July 1997), pgs. 393-400.
[5] Kirsten
Waller and others, "Trihalomethanes in Drinking Water and Spontaneous
Abortion," EPIDEMIOLOGY Vol. 9, No. 2 (March 1998), pgs. 134-140.
[6] Judith B.
Klotz and Laurie A. Pyrch, A CASE-CONTROL STUDY OF NEURAL TUBE DEFECTS
AND DRINKING WATER CONTAMINANTS (Atlanta, Ga.: Agency for Toxic
Substances and Disease Registry, January, 1998).
[7] Frank L.
Bove and others, "Public Drinking Water Contamination and Birth
Outcomes," AMERICAN JOURNAL OF EPIDEMIOLOGY Vol. 141, No. 9
(May 1, 1995), pgs. 850-862.
[8] Andrew T.
L. Chen and others, "RE: 'Public Drinking Water Contamination
and Birth Outcomes,'" AMERICAN JOURNAL OF EPIDEMIOLOGY Vol.
143, No. 11 (June 1, 1996), pgs. 1179-1180.
[9] Ann Aschengrau
and others, "Quality of Community Drinking Water and the Occurrence
of Late Adverse Pregnancy Outcomes," ARCHIVES OF ENVIRONMENTAL
HEALTH Vol. 48, No. 2 (March/April 1993), pgs. 105-113.
[10] David A.
Savitz and others, "Drinking Water and Pregnancy Outcome in
Central North Carolina: Source, Amount, and Trihalomethane Levels,"
ENVIRONMENTAL HEALTH PERSPECTIVES Vol. 103, No. 6 (June 1995), pgs.
592-596.
[11] Shanna
H. Swan and others, "A Prospective Study of Spontaneous Abortion:
Relation to Amount and Source of Drinking Water Consumed in Early
Pregnancy," EPIDEMIOLOGY Vol. 9, No. 2 (March 1998), pgs. 126-133.
[12] Kellyn
S. Betts, "Miscarriages associated with drinkingwater disinfection
byproducts, study says," ENVIRONMENTAL SCIENCE & TECHNOLOGY
[ES&T] April 1, 1998, pgs. 169A-170A.
Descriptor terms:
drinking water; trihalomethanes; chloroform; fetal deaths; miscarriages;
statistics; bromoform; bromodichloromethane; chlorodibromomethane;
thms; california; ca; atsdr; nj; new jersey; neural tube defects;
spina bifida; birth defects; epa; ottawa, cn; emporia, ks; littleton,
ma; santa clara, ca; las vegas, nv; Return
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