Science / Medicine : Water Bugs : Scientists Worry That New Tests Fail to Detect Dangerous Bacteria
The methods used to monitor the nation’s drinking water are coming under increasing fire from scientists less than three months before new monitoring techniques are scheduled to go into effect.
Not only are current monitoring approaches inadequate, critics charge, but the new methods proposed by the Environmental Protection Agency to detect microbial contamination of drinking water from sewage are substantially less effective than the old methods, according to a recent study by scientists at UC Irvine.
The adequacy of monitoring methods has attracted a great deal of interest because outbreaks of illness caused by contaminated drinking water persist in the United States. The actual number of outbreaks is unknown, since reporting is voluntary. But one study, by the Centers for Disease Control, found that from 1986 to 1988, 50 outbreaks of illness from drinking water were reported, affecting 25,846 people.
While the number of outbreaks appears to have declined in recent years, some individual instances have affected large numbers of people, the CDC reported.
“Monitoring these patterns is important because new diseases can emerge . . . possibly requiring new means of control,†CDC experts reported.
The severity of waterborne illnesses was underscored last winter when 200 residents of Cabool, Mo., were stricken with diarrhea after the town’s frozen water mains burst, leaking sewage water into the town’s supply of drinking water. The residents of Cabool were afflicted with a rare strain of the common intestinal bacterium, E . coli , that has been the cause of an increasing number of outbreaks of diarrheal illness around the world in the past eight years.
E. coli is a type of bacteria found naturally in the intestines of all mammals. The rare strain that hit Cabool, called O157:H7, is usually found in rare meat and in dairy products. But the outbreak in Missouri, in which three people died, increased concern over protecting drinking water from bacterial contamination.
According to the recent UC Irvine study, new testing procedures proposed by the EPA to monitor the safety of drinking water fail to detect any type of E. coli , including the rare, potentially fatal strain.
The failure to detect E. coli is just one of a number of criticisms the EPA is facing regarding its proposed new methods to detect microbial pollution in drinking water. The regulations are scheduled to go into effect Dec. 31.
If enacted, the new monitoring methods will weaken protection of the nation’s drinking water, some experts say.
“I’ve never seen scientists as angry as they are about this,†says Betty Olson, a UCI microbiologist. “These methods have not been adequately tested.â€
Olson’s team looked at the current EPA monitoring procedures and the proposed new tests to see if any of the tests would detect the rare E. coli strain. Routine examination of treated water is required by the Safe Drinking Water Act.
Neither the current nor the new tests detected the rare E. coli strain, and the new tests were less successful in detecting any form of E. coli . About 100 strains of E. coli have been identified, a few of which are known to cause illness.
The issue is significant, Olson says, because all water utilities face the possibility of cross-contamination of sewage and drinking water.
“These new tests are horrible. They’re fine for untreated water, but for water that has been disinfected they tend to give a lot of false results. So something could get by which would be a public health hazard,†said Olson, whose study was co-authored by Debbi Clark of UCI and researchers at the Metropolitan Water District of Southern California.
In the study, one new test proposed for use by the EPA found E. coli in only eight of 43 treated water samples contaminated with E. coli while a second test detected E. coli in only 17 of 43 contaminated samples. None of the tests, including the current standard method, detected the rare strain, E. coli O157:H7.
“It fails (much) of the time,†said Olson of the new test. “It will not detect the rare E. coli organism. We’ve looked at thousands of water samples and we’ve found E. coli in very few. But when we find E. coli we’re concerned.â€
According to Olson and EPA authorities, the new tests were touted as improved because they are quicker and less complicated than the current method.
Defenders of the new methods say that if E. coli was present in a water sample, other bacteria associated with fecal contamination would also be present that would be detected by the new tests.
But the rare E. coli strain has the unfortunate ability to outlast other bacteria, says Ed Geldreich of the EPA’s drinking water research division in Cincinnati.
“The test would pick up all the other (bacteria) if the contamination occurred within a few days (of testing),†he said. “But water is not monitored every day in small areas like Cabool, Mo.â€
Theoretically, Geldreich said, if contamination occurred two or three weeks before a water sample was taken for review, many organisms could die out, leaving the dangerous organism that would not be detected.
“Suppose everything died except this one E. coli . And we know this E. coli can survive a heck of a lot longer than all the other E. colis . So you can get a situation where it can be there and you get a negative test,†he said.
Olson says this scenario has been overlooked by the EPA.
“We feel the EPA should at least seek to develop new methods that will detect such an occurrence, rather than going ahead with one we know would not do so,†Olson said. “The EPA is changing methods without proper information and without proper testing. Until you are able to gather proper information, you shouldn’t go forth (with new regulations).â€
The EPA is in the process of reviewing public comments about the regulations, required before it can issue final rules.
“I’m aware of Betty Olson’s data. We are looking at that as well as other data that has come in,†said Paul Berger of the EPA’s office of drinking water.
Officials at the American Water Works Assn. say they are also concerned about Olson’s observations and are re-evaluating their endorsement of the new EPA monitoring tests, which are called Colilert and Coliquik.
“Our initial position concerning Colilert was in favor of it because it is a fast method and is easy to use,†said John Mannion, executive director of the AWWA. “It’s a boon to water utilities around the country, particularly smaller systems that can’t perform their own bacterial analysis because they don’t have the expertise.
“But I gather, since that time, that some concerns have arisen among some scientists, and I think those concerns have to be thrashed out before there can be commercialization of the method.â€
But Mannion said he feels it is unfair to criticize the new tests for failing to detect the rare form of E. coli because the present methods do not detect the bacterium either. He said that both the new and old systems are adequate to detect other types of E. coli .
“In general, in this country, I think it’s safe to say that treatment systems in America are handling E. coli very, very well,†Mannion said. “At the moment, we feel confident that the disinfectant process of the system copes with E. coli very effectively.â€
But Olson says not enough research money is available to study microorganisms in water and how to preserve the safety of drinking water. The EPA budget for outside research on microorganisms in water was $750,000 this year, compared to $20.6 million available to study chemicals in water, Olson maintains.
While microorganisms are known to cause disease, chemicals have not been identified as the source of any disease outbreaks, she says.
“The real illnesses that are causing people problems are not being studied,†Olson said. “We have a real risk of waterborne disease in the United States.â€
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