Study:
THMs in blood increase after showers
CHAPEL HILL, NC
Trihalomethanes (THMs),
byproducts from chlorination, appear to increase significantly
in the bloodstream after showering, says a study by researchers
at the University of North Carolina (UNC) at Chapel Hill School
of Public Health.
Public health experts
suspect the chemicals might boost the risk of cancer and contribute
to reproductive problems such as miscarriages, a release by UNC
said. The study involved 50 women living in Cobb County, GA, and
Corpus Christi, TX, and indicated that showering shifted the distribution
of THMs in blood toward that found in the tap water.
Researchers picked
those cities because water supplies in the former showed "moderately
high" levels of chloroform, the most highly chlorinated THM,
and, in the latter, lower total THM concentrations but a higher
proportion of brominated species, which UNC said are believed
to be potentially more hazardous.
The study aimed to
evaluate whether health workers could use THM concentrations in
drinking water to predict concentrations in people's blood.
Another finding was
that the distribution of the four types of chlorinated
and brominated THM species detected in the women's blood reflected
the differences of type and concentration in their tap water.
Through blood sample analysis, researchers measured THMs in the
blood of 25 women at each site before and soon after they showered,
and compared those levels to concentrations found in tap water
in their houses, the study said. THM concentrations were around
1,000 times lower in blood than in tap water, but after the showers,
median levels in blood increased by a factor of four, said Miles.
"This showed THMs were getting into blood as a result of
water use. It could not address, however, whether the concentrations
were harmful or were linked to any particular health problem,"
Miles added.
Chlorination of tap
water should be studied further to prevent THMs,
suggested Amy M. Miles, one of the authors of the report about
the study that was published in the journal Environmental Science
& Technology. Support for the research came from the American
Water Works Research Foundation, Denver; the Centers for Diseases
Control and Prevention, Atlanta; and the EPA.
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