No day at the beach in Huntington Beach
Our planet's beleaguered oceans have been making headlines all
year, with gloomy reports on collapsing fisheries, invasive
species, plastic pollution and more. But a less-publicized issue
hits closer to home, especially as summer revelers flock to the
beach in droves.
Put bluntly, the problem is poop. Fecal pollution--mainly from
raw sewage--is contaminating large stretches of recreational
water from the Gulf Coast to the Great Lakes.
Swimming in unsafe water can lead to sore throats and diarrhea,
as well as more serious illnesses like meningitis and severe
gastro-enteritis. Recent research has shown that, after many
years of decline, death rates from microbial gastrointestinal
illness are on the rise. "Recreational exposures clearly play a
role in causing these illnesses," says epidemiologist Rebecca
Calderon of the U.S. Environmental Protection Agency.
Pollution caused more than 12,000 beach closings and advisories
in 2002--the second highest number in 13 years--according to a
study by the Natural Resources Defense Council. (The 2001
numbers were slightly higher, mostly because of drought
conditions in 2002.) The continual rise in "no-swimming" days in
part reflects better testing standards, the report notes, but
scientists disagree over how to best monitor pollution and warn
For years, the standard analysis has been based on coliforms--bacteria
that give an estimate of the amount of feces in a sample. Most
officials take one water sample a day and then post a warning
sign on the beach when bacteria levels exceed a specified value.
"It's a flawed system," observes Mark Sobsey, an environmental
microbiologist at the University of North Carolina at Chapel
Hill. Since bacteria must be grown, an analysis can take 24
hours or more. "We are still in this dilemma of making decisions
about water that has already come and gone," he remarks.
To assist state and local officials with monitoring programs,
the EPA introduced the Beaches Environmental Assessment and
Coastal Health (BEACH) Act in October 2000. One goal of the
BEACH Act was to spur development of "rapid indicators" to
measure water quality on an almost continuous basis. "Obviously,
people would like it to be done 10 seconds or less, but we
thought that was pretty unrealistic," says Al Dufour of EPA's
National Exposure Research Laboratory. "There was an arbitrary
goal set up: We were going to attempt to measure water quality
in two hours or less."
A number of new technologies that meet this standard are now
being tested in various environments, and most experts agree
they are a step in the right direction. But recent research
suggests that rapid indicators might not be a panacea.
Stanley Grant of the University of California at Irvine has
analyzed warning errors at Huntington
Beach, Calif. His findings, published the May 1 issue of
Environmental Science & Technology, suggest that even if sample
turnaround were almost instantaneous, error rates in beach
warnings would still be quite high. Grant's work points to a
more fundamental problem: the current "binary" advisory
scheme--wherein a warning sign is either posted or not, giving
the public no further information--is intrinsically error prone,
he asserts. He recommends switching to an "analogue" system,
similar to the one used to issue ozone warnings in urban areas,
assigning a letter grade to beaches from "A" to "F."
Other researchers maintain faith in rapid indicators. Stephen
Weisberg, executive director of the Southern California Coastal
Water Research Project, agrees with Grant that if officials are
taking only one sample each day, then decreasing sampling time
will do little good. "But if you sample once in the morning,
then get the results right away and find out you have a high
level, you can sample again five times in different places
before noon," he counters. Weisberg and Sobsey were among the
experts on the committee for a recent National Research Council
(NRC) report that addressed indicators of waterborne disease.
The report stressed the importance of rapid indicators but
placed them in the context of a three-phase approach to
The first phase is simply an early warning, attainable through
fast and cheap pollution detection techniques. "You don't need a
lot of specificity," Weisberg explains. "You can have some false
positives, but what you don't want is a lot of false negatives."
A false negative means people are swimming in polluted water.
Phase two of the NRC framework--confirmation--requires a larger
set of tools to put the problem in a public risk context.
"Invariably, that means human health or epidemiological studies,
where you quantify the risk of people becoming ill from
swimming," Sobsey says. He advocates following the lead of
European scientists, citing a study conducted by British
researchers from the 1990s in which they made a grid in the
water and sampled continually for days, simultaneously measuring
water quality and exposure levels for specific swimmers.
The EPA is now conducting just such a study in collaboration
with the Centers for Disease Control and Prevention, Calderon
reports. The National Epidemiological and Environmental
Assessment of Recreational (NEEAR) Water Study is combining data
from rapid indicators with beachgoer interviews to get a clearer
picture of the link between water quality and human health. So
far researchers have studied two freshwater beaches on Lake
Michigan and Lake Erie, but the data await analysis.
In the third and final phase of the NRC framework, the emphasis
shifts to ascertaining what caused the problem and how it can be
fixed. This phase requires that investigators use genetic
techniques to distinguish human and animal sources, which can
indicate different pollution sources. If, for example, a human
source is detected, it is most likely from a leaky sewer pipe,
Weisberg notes. Pinpointing the source is also important because
it is possible, although not well established, that animal feces
are less virulent than human feces. "Not that we're saying you
want to swim in bird poop," Wesiberg says. "But in the longer
term, we may be in a position to set different standards and
adjust our warning systems." Tools that quickly differentiate
between human and animal sources using complex libraries of
genetic information are still years away. A simpler method,
however, might be to test the samples for viruses rather than
sequencing DNA from source organisms. Finding a human virus
would automatically rule out an animal source, Dufour explains.
A detailed understanding of contamination sources could also
pave the way for models that forecast pollution events. Grant's
study this past spring noted that pollution levels at Huntington
Beach were consistently higher at high tide, and rain has long
been considered a good predictor of troubled ocean waters. "The
numbers almost invariably go up dramatically when it rains,"
Sobsey says, because storms tend to overwhelm sewage systems.
The EPA has put together a small group of researchers to develop
a forecasting system aimed at keeping officials a day ahead of
problems. "This [would be] far better than the 'I can tell you
tomorrow what you swam in today' scenario we are in," Calderon
But is an accurate forecasting system really just a pipe dream'
Dufour says no: "After all, just think about the weathermen;
they're getting better all the time.