Chlorination is used primarily to prevent
pathogenic microorganisms from growing. Previous research has shown that
many constituents of urine including urea, uric acid, and amino acids,
interact with chlorine to produce potentially hazardous disinfection
byproducts in swimming pools. However, chemicals from pharmaceuticals
and personal care products, or PPCPs, also could be interacting with
chlorine, producing potentially harmful byproducts.
"The whole motivation for examining
pharmaceuticals and personal care products is that there is this unknown
potential for them to bring about undesired or unexpected effects in an
exposed population," said Ernest R. Blatchley III, a professor with a
joint appointment in the Lyles School of Civil Engineering and the
Division of Environmental and Ecological Engineering at Purdue
University. "There are literally thousands of chemicals from
pharmaceuticals and personal care products that could be getting into
swimming pool water."
A research group led by Ching-Hua Huang, a
professor in the School of Civil and Environmental Engineering at the
Georgia Institute of Technology, has developed an analytical technique
that identifies and quantifies 32 pharmaceuticals and personal care
products in water.
"Because professor Huang had already developed an
analytical method, which is a non-trivial effort, we thought, 'Why not
use it and see what we find in swimming pools?" said Blatchley, working
with Huang and former Purdue doctoral student ShihChi Weng, now a
postdoctoral fellow at Johns Hopkins University. Water samples were
taken from indoor swimming pools in Indiana and Georgia.
Findings are detailed in a research paper that
appeared in December in the journal Environmental Science and Technology
Letters. Of the 32 chemicals investigated, the researchers detected
three: N,N-diethyl-m-toluamide, known as DEET, the active ingredient in
insect repellants; caffeine; and tri(2-chloroethyl)-phosphate (TCEP), a
flame retardant.
"The other 29 could have been present at
concentrations below the detection level," Blatchley said. "And because
there are literally thousands of pharmaceuticals, this is just a small
subset of compounds that could be present in swimming pools. The main
issue is that the release of chemicals into a place like a swimming pool
is completely uncontrolled and unknown. I don't want to be an alarmist.
We haven't discovered anything that would be cause for alarm right now,
but the bottom line is we just don't know."
Some chemicals are volatile, which means they can
escape into the air to be inhaled. Others can be ingested or absorbed
through the skin.
"Swimmers are exposed to chemicals through three
different routes: You can inhale, you can ingest and it can go through
your skin. So the exposure you receive in a swimming pool setting is
potentially much more extensive than the exposure you would receive by
just one route alone," Blatchley said.
His previous research has shown that certain
airborne contaminants are created when chlorine reacts with sweat and
urine in indoor swimming pools. Pharmaceuticals may get into swimming
pool water from personal care products applied to the skin such as
insect repellant, makeup and sunscreen. Many pharmaceuticals that are
ingested are not fully metabolized by the body and are excreted in sweat
and urine.
"Urine, I think, is really the primary mode of
introduction," Blatchley said. "When it comes to pharmaceuticals, these
are chemicals designed to be biologically active at pretty low
concentrations. Birth control pills, for example, contain hormones. If
those chemicals and others are present, especially in a mixture in a
water sample that humans are going to be exposed to, then what are the
consequences of that? That is a largely unanswered question."
The findings also suggest the potential for accumulation of topically applied PPCP compounds in pools.
"Not surprisingly, the concentration of DEET was
much higher in Georgia than in Indiana," he said. "Generally, the
results of this study point to the importance of proper hygiene habits
of swimmers."
The detection method uses techniques called liquid chromatography and tandem mass spectroscopy.
"We also performed experiments in the lab under
much more controlled conditions where we took pure compounds of these
PPCPs and we exposed them to chlorine to see how fast they react,"
Blatchley said. "It turns out some react very quickly and others very
slowly or not at all. We did that because we are interested not only in
the chemicals that may end up in the swimming pool, but also, once they
do end up there, what happens to them? Do they degrade? If so, what do
they degrade to? These too are unanswered questions."
The research paper was authored by Weng; Georgia
Tech doctoral student Peizhe Sun; Weiwei Ben, a visiting scholar at
Georgia Tech from the Research Center for Eco-Environmental Sciences,
Chinese Academy of Sciences; Huang; Purdue graduate student Lester T.
Lee; and Blatchley.
According to the federal Centers for Disease
Control and Prevention, recreational water illnesses (RWIs) are caused
by germs spread by swallowing, breathing in mists or aerosols, or having
contact with contaminated water. RWIs also can be caused by chemicals
in the water or chemicals that evaporate from the water and cause indoor
air quality problems. A wide variety of RWI infections include
gastrointestinal, skin, ear, respiratory, eye, neurologic, and
wound-related. The most commonly reported RWI is diarrhea.
The research is ongoing.
"What we are planning to do is look at, for
example, sales statistics for pharmaceuticals and personal care products
to see which ones of these various compounds are sold in the largest
quantities and then to consider their structure and which of them could
accumulate in a swimming pool and might react with chlorine to produce
other compounds," he said.
In the previous research led by Blatchley, it was
shown that uric acid in urine generates potentially hazardous "volatile
disinfection byproducts" in swimming pools by interacting with
chlorine. The disinfection byproducts include cyanogen chloride (CNCl)
and trichloramine (NCl3). Cyanogen chloride is a toxic compound that
affects many organs, including the lungs, heart and central nervous
system by inhalation. Trichloramine has been associated with acute lung
injury in accidental, occupational, or recreational exposures to
chlorine-based disinfectants.
The previous research suggested that about 93 percent of uric acid introduced to pools comes from human urine.
Writer: Emil Venere, 765-494-4709, venere@purdue.edu
Source: Ernest R. Blatchley III, (765) 494-0316, blatch@ecn.purdue.edu