MicrobesIncreasinglyViewed as WaterQuality Threat

The EmergingContaminants

by Joe Gelt

ManyU.S. citizens believe that

thanks to our advanced tech-nology and enlightened public policywe can consume without risk thefood and water that are readily avail-able to most of us, as citizens of arich and privileged country. Some ofthose who subscribe to this buoyantand comforting attitude, however,may have lately experienced secondthoughts. Because of various recentand widely reported incidents, manypeople are feeling concern about thequality and safety of our food andwater. This is not surprising; someof these incidents have resulted inserious, widespread sickness, evendeath.

For example, several incidentswere reported of people becomingsick from eating undercooked beefat fast food restaurants. In other mci-dents, more than 70 people becamesick and one died in late 1996 fromdrinking Odwalla apple juice, a

New waterbome microbialpathogens are being discovered, and research is under-way to develop improved methodsfor detection and treatment ofmicrobials indrinking water. (Photo courtesy ofPublicom Incorporated)

brand sold at health food stores, andlast year lettuce from a smallproducer sickened at least 61 peoplein the U.S. Northeast. The latter twoincidents were related to a strain ofE. coli bacteria.

Water too has raised public healthconcerns. Microbial pathogens orcontaminants in drinking water arebeing blamed for various gastrointes-tinal illnesses that have occurred indifferent parts of the country. U.S.citizens, in the unlikely event they hadeven given much thought to con-taminated drinking water, would haveconsidered it a condition out of the

past or one associated with develop-ing countries. Now waterborne sick-ness from microbial contaminants,some with strange and unlikelysounding names - e.g., Oyp-tosporidium, Giardia, Legionella andNorwalk virus - has become a seem-ingly modern concern even forpeople living in the United States.

Estimates project from seven toabout 30 million Americans eachyear develop a gastrointestinal ill-ness, possibly from drinking con-taminated water. EPA also providesa wide range of figures when estimat-ing the nation's annual medical and

WATER RESOURCES RESEARCH CENTER . COLLEGE OF AGRICULTURETHE UNIVERSITY OF ARIZONA

y ARROYO y

Vol. 10 No. 2 March 1998

lost productivity costs due to water-borne illnesses, from $3 billion to $22billion. Of much greater concern arethe deaths related to microbial con-taminants in drinking water. TheCenters for Disease Control andPrevention estimates 900 to 1,000people die each year from microbialillnesses from U.S. drinking water.Other estimates run as high as 1,200deaths. Although difficult to pindown, such figures indicate the exist-ence of a serious problem.

Microbial Contaminantsin History

Microorganismsare present

everywhere in our environment,in soil, air, food and water. Alsocalled microbes, microorganisms areliving organisms, generally observableonly through a microscope. Our ex-posure to them causes harmlessmicrobial flora to establish in ourbodies, although some microbes arepathogens and can cause diseases.These diseases are considered water-borne if the pathogens are trans-mitted by water, to infect humans oranimals that ingest the contaminatedwater. Diseases transmitted by waterare primarily those found in the intes-tinal discharges of humans or animals

The presence of microbial con-taminants in drinking water hasplagued humans throughout history.In fact, outbreaks of cholera, typhoidfever and dysentery are recurringthemes in early U.S. history. For ex-ample, in 1850 and 1851, an especiallyaggressive outbreak of cholera oc-curred in Sonora, an area that in-cluded Tucson at that time. Morethan 1,000 people died in north-western Sonora, while in Tucson the122 deaths that occurred in 1851 farexceeded the number of recordedbirths that year which were 19.

Due to microbial pathogens, aharsh reality confronted those seek-ing gold and glory in the hills of

California. "Diarrhea," reported adoctor in Sacramento, "was sogeneral during the fall and wintermonths and degenerated so frequent-ly into a chronic and fatal malady thatit has been popularly regarded as thedisease of California...." Waterbornemicrobial pathogens cause a wholerange of diarrhea! diseases.

(Possibly California miners wouldhave fared better if they heeded thewords of Moses who showed the goodsense of a sanitation engineer inDeuteronomy 23: 12, 13 when hewarned his followers: "Thou shallhave a place also without the camp,wither thou shall go forth abroad:And thou shalt have a paddle uponthy weapon; and it shall be, whenthou wilt ease thyself abroad, thoushalt dig therewith, and shalt turnback and cover that which comcthfrom thee." The hazards of fecal con-tamination and the principles of basicsanitation were recognized early.)

The occurrence of such outbreaksalerted people to the hazards ofdrinking contaminated water andprompted investigations into ways toprevent the occurrence of waterborneillnesses. Public health officials even-tually achieved success in controllingthe more common forms of water-borne diseases, at least in the UnitedStates and other developed countries.Progress was due to the adoption ofpublic health measures as well as theimplementation of important watertreatment techniques, such as filtra-tion, disinfection and sewage treat-ment. Some believed the battle, if notwon, was at least under control.

Emerging Contaminants

Waterbornemicrobial con-

taminants, however, have at-tracted renewed attention, bothwithin the scientific community andamong the public. Once thought to heunder control, they are now referredto as the "emerging drinking water

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contaminants." What in fact is emerg-ing is an expanded awareness of thepresence of previously undetectedmicrobial contaminants in drinkingwater and their effects on humanhealth. Also emerging is the field ofenvironmental microbiology, as newmicrobial pathogcns are being dis-covered and research is underway todevelop improved methods for detect-ing and treating microbials in drink-ing water.

Microsporidia is an example of anemerging pathogen that is attractingattention. Potentially waterhorne, thispathogen is recognized as causing dis-ease among AIDS patients, althoughhealthy persons also may be suscep-tible to microsporidia. Because of itssinai! size, microsporidia may survivefiltration, and studies thus far indicatethat the pathogen will be fairly resis-tant to many drinking water disinfec-tants. With more research and thedevelopment of improved detectionmethods, researchers will be able tobetter determine the occurrence ofmicrosporidia, both in humans andthe environment. Some researchers

Arroyo is published by the WaterResources Research Center, Collegeof Agriculture, 350 N. CampbellAvenue. University of Arizona, Tuc-son, Arizona 85721; 520-792-9591.Each issue of Arroyo focuses on awater topic of current interest toArizona. A list of past Arroyo topicsis available upon request, and back is-sues can be obtained. Both list andpast copies can be accessed via theWorld Wide Web(http://ag.arizona.edu/AZWATER/).Subscriptions are free, and multiplecopies are available fer educationalpurposes. The editor invites com-ments and suggestions.

Water Resources Research CenterActing Director, Peter WierengaEditor, Joe Gelt,Email; jgelt@ag.arizona.edu

-Microscopic view of bacteria, virusesand prot ozoa. (top to bottom)

believe this microorganism may even-tually need to be monitored and con-trolled in drinking water supplies.

H. pylon is another emergingpathogen. Common among people ex-posed to poor hygienic conditionsfrom childhood, H. pylon also hasbeen found, although much less fre-quently, among the socioeconomic ad-vantaged. Its source is not known, butwater is thought to be a likely route oftransmission. H. pylon causes inflam-

mation of the stomach and seems tobe a factor in the development ofduodenal ulcers. It also is thought toplay a causal role in the chain ofevents leading to gastric cancer. Theoccurrence of H. pylon ranges fromless than one percent of the popula-tion of industrialized nations to threeto eight percent in developingcountries. Researchers continue tostudy this pathogen.

These and other microbial con-taminants are increasingly attractingthe concern of public health autho-rities as well as an interdisciplinaryarray of experts in such fields asmicrobiology, engineering, epidemiol-ogy and risk assessment.

Where Do TheyCome From?

Watcrbornediseases result from

drinking fecal contaminatedwater. To explain the presence ofmicrobial contaminants in drinkingwater is to describe a circuitousroute, from a human or animal sourceback to a human or animal via drink-ing water. Microbial contaminants fol-low a fecal-oral route.

Bacteria, viruses, and protozoa arcthe microorganism groups containingpathogens of primary concern in thestudy of waterborne disease. Humansources account for viruses, whileboth animal and human waste con-tribute protozoa to water. For ex-ample, cattle are considered thesource of much Ciyptosporidium, andGiardia is often traced to beavers.Both Oyptosporidiwn and Giardiaare protozoa.

Each day the average human ex-cretes about 38 grams of urea, mostlyurine, and 20 grams of solids in feces.The excreta contains billions ofmicrobes. These microbes cannotonly survive, but also multiply inwater and are made up of a widerange of organisms, includingpathogenic microbes, which even

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healthy people excrete. Others whohave a disease or who are carriers ofa disease-producing microorganismare a more obvious source of water-borne infections. Estimates indicatethat about five percent of those whohave contacted an enteric or intes-tinal disease remain life-long carriers,even after having recovered from thedisease.

That these intestinal microbial con-taminants can infect a drinking watersource may at first seem puzzling,especially to citizens of a country thatprides itself on its public health stand-ards. Yet through natural flow or acci-dent, various types of water can inter-connect and flow together. For ex-ample, storm water runoff fromresidential, rural and urban areas cancarry waste material from domesticpets and wildlife, to collect in surfacewaters and even enter groundwater.Through accident or equipmentfailure, sewage, a rich source ofmicrobial contamination, might comeinto contact with drinking water.Also, defective on-site wastewater dis-posal or septic systems in rural andother residential areas can contributelarge numbers of coliforms and otherbacteria to both surface water andgroundwater.

These contaminants occur widelyand are not limited to areas inhabitedby humans. A deer or other wildlifefeeding by a clear-flowing, pristinestream in an untrammeled forestedarea is an appealing image. Thishardy specimen of wildlife, however,can contribute contaminants to thestream to infect a downstream hikerenjoying a sip of spring water directfrom the source. Cattle also add con-taminants to water in isolated areas.Cattle graze many back country areasand drink from streams that then flowto other areas or into other watersources.

Fecal contamination can occur inindirect and seemingly unlikely ways.Authorities suspect the contamina-tion of Odwalla apple juice was

caused when the processing plantpressed a decayed apple that had fal-len to the ground and came into con-tact with feces, possibly from a deer.This sickened 70 people and resultedin one death.

Two Scenarios

brief review of two case studies ofoutbreaks of waterborne diseases

will demonstrate the effects such dis-eases have on people, as well asproviding information about theorigins of such outbreaks and othercircumstances related to them.

Milwaukee In Milwaukee, a much-publicized 1993 outbreak of Cyp-tosporidiurn demonstrated the vul-nerability of our country's water sup-plies to microbial contamination. Theoutbreak stands as a defining event inour increased awareness of thehazards of microbial pathogens indrinking water.

The Milwaukee outbreak of Cyp-tosporidium caused the death of 100people, most of whom were elderly,AIDS or cancer patients or otherwisesusceptible to illness. Further, morethan 400,000 others, or about half thecity's population, became sick.Symptoms included water diarrhea,stomach cramps, an upset stomach,and a slight fever. About 725,000 lost"work/school days" were recordedduring the 6-week outbreak, at a costof about $166 million in medical char-ges and lost work time. Water qualitytests at the time did not indicate theexistence of a serious problem.

Since 1992 Ciyptosporidium out-breaks have occurred in various otherparts of the country including two inWashington state and one each inMinnesota and Nevada. The LasVegas, Nevada outbreak caused thedeaths of 19 AIDS patients.

Ciyptosporidium has been recog-nized as a human pathogen only since1976. Initially it was thought to infectprimarily immunocompromised in-

dividuals; i.e. those with a weak im-mune system. With newly developedlaboratory diagnostic techniques, out-breaks were detected among thosewith healthy immune systems. Cattleare believed to be the origin of theMilwaukee outbreak, althoughhumans also can be a source. Studiesindicate that Ciyptosporidiuin ispresent in about 65 to 97 percent ofthe surface water in the UnitedStates. Neither chlorine disinfectantnor standard water filtration systemsfully remove this pathogen from drink-ing water.

Tate, Georgia In January 1982, anoutbreak of Norwalk gastroenteritisoccurred in Tate, a rural communityin north Georgia. Prior to the out-

San ildefonso pottely design

break, the community received heavyrainfall, approximately 4.5 inches onJanuary 2-3. After the storm, resi-dents served by the municipal waterutility noticed their tap water ap-peared turbid. Shortly thereafter resi-dents began reporting gastrointestinalillnesses. Symptoms included nausea,abdominal cramps, diarrhea, and/orvomiting, headache, myalgia and low-grade fever. For most persons, the ill-ness lasted from one to three days. Ofthe 800 persons served by themunicipal water source, 500 may havebeen ill during the outbreak

Investigations revealed that one ofthe three springs the utility used wasunprotected and flowed behindseveral houses with septic tanks. Test-ing of the spring indicated it was the

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likely source of contamination.Both of the above incidents repre-

sent outbreaks of waterborne dis-eases. According to the Centers forDisease Control an outbreak is two ormore illnesses traced to a commonsource. The above outbreaks, al-though ranging greatly in the numbersaffected, are more the exception thanthe norm. More typical and far morecommon are intermittent occurren-ces, with individuals from differentand various locations becoming sickfrom waterborne pathogens. Thesegenerally go unreported to healthauthorities. This pattern complicatesthe tracking of such diseases.

The Problem

partof the reason microbial con-

taminants are receiving belated at-tention, at least in developedcountries, is that their effects are dif-ficult to determine For example, justto ascertain how many people in theUnited States have become sick frommicrobial contaminants in drinkingwater is a formidable challenge. Formost people, the symptoms are notparticularly worrisome, and mostcases go unreported. A person ex-periencing fever, diarrhea, vomitingand nausea may not seek medical at-tention, especially if the symptomsare gone within a few days. The condi-tion may be self-diagnosed as a touchof flu or blamed on yesterday's spicylunch. In truth, however, the personmay be experiencing an acutegastrointestinal infection acquiredfrom drinking water.

Some recent evidence indicates,however, the effects of microbial con-taminants may not be limited only toshort-term gastrointestinal diseases.Recent findings show that waterbornecontaminants also may be linked tocertain long-term chronic conditions,such as diabetes and heart disease.Links with miscarriages also aresuspected.

Only when large outbreaks of awaterborne disease occur - as hap-pened in Milwaukee and Las Vegas -is the event deemed newsworthy.Then the havoc microbial con-taminants can wreak becomesgenerally known. Health officials thentake special note and investigate todetermine a single source for the dis-ease and order lab tests. Also, theCenters for Disease Control would bealerted.

Further complicating the situationis that doctors are unlikely to be onthe look out for rare or emergingpathogens. Confronted with thesymptoms of a waterborne illness, adoctor is unlikely to believe lab testsare justified. If done, the lab workcould alert medical personnel of thepresence of waterborne pathogens.

For a number of reasons, problemsassociated with microbial pathogensin drinking water are expected toworsen in the future. For one, thepopulation most at risk to the effectsof microbial contaminants is increas-ing. Not all people are equally af-fected. Those most at risk include thevery young, the elderly, pregnantwoman, and immunocompromised in-dividuals, i.e., people with a weak im-mune system including AIDSpatients, cancer patients undergoingchemotherapy and organ transplantpatients. Now believed to make up 20to 25 percent of the U.S. population,this high-risk group is expected to in-crease in the future.

For example, the ranks of those 65and over are increasing. By the year2010, people over the age of sixty-fivewill constitute the most rapidly multi-plying sector of the population. Thenumber of immuno-compromised in-dividuals also is expected to increase.This is partly because of the greaterfrequency of organ and tissuetransplants. Also, new forms of can-cer treatment involve the use of im-munosuppressive drugs. What thismeans, in effect, is more people atrisk of serious illness and even death

from waterborne pathogens.The American Academy of Micro-

biology identifies the aging anddeteriorating condition of water treat-ment and delivery systems as alsocontributing to future increases ofwaterborne illnesses. This is morelikely to be a problem in some largeurban or inner city areas of developedcountries. Pathogenic bacteria growin such systems and can pose seriousthreats to human health.

A change in U.S. agriculturalproduction methods also portends anincrease in microbial contaminationof water. The number of livestockfarms in the nation has been dwin-dling, with the surviving farms con-solidating into larger operations.Larger operations on less land meansless space to get rid of animal waste.The result is a doubling of the num-ber of animal-waste spills fromstorage lagoons, polluting rivers andstreams. Some of these lagoons canbe 20 feet deep and half a mile wide.

A recent report, "Animal WastePollution in America," produced bythe Minority Staff of the SenateAgricultural Committee, states that60 percent of rivers and streams havebeen impaired by agricultural runoff.Congress is expected to hold hearingssoon on the problem. Legislation islikely to be proposed for the first timeto require farmers to handle animalwaste much as industries handle toxicbyproducts.

Some officials believe recentagricultural developments will resultin an increased transmission ofanimal pathogens to humans. Also,due to urban spread in certain partsof the country, high-density animaloperations are occurring closer tourban areas, further complicating thesituation.

Testing or Monitoringnumber of problems beset water

quality experts in their efforts to

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determine the presence of microbialpathogens in drinking water. As aresult, testing for microbials lacks theefficiency and accuracy possible whentesting for chemical contaminants indrinking water. Further, for eachgroup of microbes, whether protozoa,virus or bacteria, the method mustcope with a different set of conditionsor characteristics that can complicatethe task of identifying particularmicrobes.

For example, pathogenic protozoaand viruses are likely to be present inwater in very low numbers. Their low-level occurrence, however, does notensure relatively uncontaminatedwater since it takes only one protozoaor virus in a water system to infect aperson with a waterborne disease.(Bacteria are different. Some requireonly 10, but usually the infectiousdose is closer to 1,000.)

The occurrence of viruses andprotozoa at very low numbers createsdifficulties when testing for them indrinking water. Present methods re-quire sampling large quantities ofwater to better ascertain the presenceof an infectious microbe. Just howmuch water to test before determin-ing the water source is relatively freeof pathogens and at an acceptablerisk for drinking is in question. EPA'sgeneral rule is one infection per10,000 people as an acceptable risk. Isthis, however, an achievable goalwhen testing for viruses and protozoain drinking water?

At present, viruses and protozoaare sampled from 400 to 1,000 litersof water. An individual consumes onthe average about two liters of waterper day. In other words, the absenceof pathogens in 1,000 liters of watermay protect only 500 people with ab-solute assurance. (A case might bemade, however, that such a test doesin fact provide a valid statisticalsample.) To reach the EPA goal ofone infection in 10,000 people, 20,000liters of water would need to betested for absolute assurance. To test

such a vast quantity of water forpathogens would be a formidabletask.

Timing also is a factor. Periodictesting may not indicate the presenceof pathogens in drinking water. This,however, may not be an accurate in-dication of the microbial quality ofthe water. Bacteria can "bloom"under favorable conditions, with abloom occurring between scheduledtesting periods. As a result, a testmight not indicate the presence ofpathogenic bacteria. Also, intermit-tent contamination can occur fromhuman or animal sources, possiblyafter water quality sampling or testinghas been done.

Testing for bacteria is done bygrowing bacteria in a growth medium.This involves adding a water sampleto a nutrient media and then incubat-ing. Bacteria that are present will util-

ize the nutrients and grow into anincreasingly turbid solution. Thismethod is generally adequate formost kinds of bacteria because theymultiple very rapidly, a generationgrowing sometimes within 20 minutes,with visible results occurring between24 and 72 hours.

Cell cultures are used to test main-ly for viruses, but also are used forprotozoa. This method involves grow-ing lab stocks of human or monkeycells and then subjecting them to awater sample. Any pathogens that arepresent infect and eventually killenough cells to produce a visual ef-fect. This can be a time-consumingprocess. The generational growth forthe fastest growing virus is five hours,with visible results appearing withinthree days to three weeks. Protozoatake even longer because of theirmore complex life cycle. Testing for

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protozoa, however, is more oftendone with microscopic analysis, alabor-intensive task performed byhighly trained technicians.

Recent scientific advances holdpromise that waterborne pathogenscan be more quickly and accuratelydetected. For example, because ofdevelopments in molecular biology,organisms can now be identified byanalyzing DNA from water sampleswith polymerase chain reaction(PCR) techniques or oligonucleotideprobes. Also, a technique developedat the University of Arizona appliesmolecular methodology to cell cultureto detect organisms in water within 24to 48 hours. With improved methodsfor detecting microorganisms fromwater samples and identifying themwith molecular methodologies, num-bers of specific pathogens in watercan be targeted more quickly and

SOME WATERBORNE DISEASES OFCONCERN IN THE UNITED STATES

Disease Microbial Agent General Symptoms

Amebiasis Protozoan(Entamoeba histolytica)

Abdominal discomfort, fatigue, diarrhea, flatulence,weight loss

Campylobacteriosis Bacterium(C'ampylobacterjejuni)

Fever, abdominal pain, diarrhea

Cholera Bacterium(Vibrio cholerae)

Watery diarrhea, vomiting, occasional muscle cramps

Cryptosporidiosis Protozoan(Cryptosporidium parvum)

Diarrhea, abdominal discomfort

Giardiasis Protozoan(Giardia lomb/ia)

Diarrhea, abdominal discomfort

Hepatitis Virus(hepatitis A)

Fever, chills, abdominal discomfort, jaundice, dark urine

Shigel losis Bacterium(Shigella species)

Fever, diarrhea, bloody stool

Typhoid fever Bacterium(Salmone/la lyphi)

Fever, headache, constipation, appetite loss, nausea, diarrhea,vomiting, appearance of abdominal rash

ViralGastroenteritis

Viruses(Norwalk, rotavirus and other types)

Fever, headache, gastrointestinal discomfort, vomiting,diarrhea

specifically than was previously pos-sible.

For some utilities, especiallysmaller utilities, the cost of using thisdeveloping technology may beprohibitively expensive. As futurewater quality standards increasinglyinclude various microbial con-taminants, such utilities will be at afinancial disadvantage to accuratelytest and treat their water for certainpathogens.

Tests Have Limitations

espite advances being made inmicrobial testing techniques

some pathogens in drinking waterremain undetected. Their presence inwater is evident when a number ofpeople become ill with a waterhorneillness and a common source of drink-ing water is identified. Identifying thespecific microbial that caused the ill-ness, however, may defy the experts'best efforts. In fact, no agent is iden-tified as the specific cause in 50 per-cent of waterborne outbreaks.

It might be that a particularmicrobial has not yet been identifiedas a waterborne pathogen. For ex-ample, C'iyptosporidium was firstrecognized as a source of sickness inhumans as early as 1976, but was notlinked to water until 1985. Until 1985,therefore, waterborne outbreakscaused by Ciyptosporidium werereported as coming from an unknowncause. Scientists believe other water-borne pathogens are in a similarcategory as Ciyptosporidium wasprior to 1985. A microbe may be iden-tified as a source of sickness in theclinic, but not yet recognized as awaterhorne pathogen because testsare not yet available to detect itspresence in low numbers.

Others microbials are known toboth cause disease and to be water-borne but no methods exist to detecttheir presence in water. For example,clinical studies have identified the

Norwalk virus as the leading cause ofviral waterborne disease in the world,and it has been linked to large out-breaks. Yet, no cultural methods existto detect its presence in largevolumes of water. Viruses are espe-cially difficult to detect. Of the about140 different viruses currently iden-tified as transmitted by water, culturaltests are developed for about only 60percent of them.

The lack of a methodology fordetermining the presence of certainpathogens in drinking water compli-cates efforts to regulate them. For ex-ample, EPA, as part of the revisionsto the Safe Drinking Water Act,recently issued a list of proposed newdrinking water contaminants to regu-late. The list includes 13 microbiologi-cal contaminants. However, for someof the listed contaminants - e.g.Cyclospora - no method exists fordetecting them in drinking water.

Meanwhile EPA prescribes a long-established method for monitoringthe microbial quality of drinkingwater that is based on the presence ofcoliform bacteria. Not likely to bepathogenic themselves, coliform bac-teria serve as an indicator, theirpresence in a water sample indicatingthat drinking water may be con-taminated with human wastes. If thecoliform bacteria count is high, fur-ther testing is done for fecal coli-form. Standardized and relativelyeasy and inexpensive to use, tests forcoliform bacteria are more readily ad-ministered than tests determining thepresence of individual pathogens.

A major failing of the test is its un-reliability in indicating the presenceof several important pathogens, in-cluding Legionella, most pathogenicviruses, Ctyptosporidium and Giardia.For example, in Milwaukee and LasVegas water that met standards forcoliform bacteria did not prevent out-breaks Oyptosporidium. Not surpris-ingly, EPA's reliance on the testing ofcoliform bacteria to determine themicrobiological quality of drinking

water is attracting criticism. Critics in-clude the American Water Works As-sociation, the primary trade associa-tion representing U.S. water utilities,which has proposed that EPA nolonger require water utilities tomonitor for total coliform bacteria.

Drinking Water ikeatment

Microbialcontaminants present a

challenge to water treatment ex-perts. Established disinfection andfiltration techniques do not alwaysremove such contaminants fromdrinking water. The effectiveness ofwater treatment varies dependingupon whether the waterborne con-taminant is a bacteria, virus orprotozoa parasite. Bacteria are theleast troublesome and are generallyremoved by current water treatmentprocesses. Diseases such as Salm onel-la, typhus, dysentery and other bac-terial diseases are fairly well control-led, at least in developed countries,through effective water treatment pro-cedures.

Viruses present a greater chal-lenge. They are generally hardier thanbacteria, although they too can becontrolled, but with increasedamounts of disinfectant. Viruseslinked to waterborne disease haveprotein protective coats and are con-sidered to be about 100 times moreresistant to disinfectant than are bac-teria. Key waterborne pathogenicviruses include hepatitis A and Nor-walk virus.

Pathogenic protozoa parasites arethe problem microbial, the con-taminant that poses the greatest riskto human health. Unlike bacteria andviruses, protozoa parasites are resis-tant to commonly used treatment pro-cedures. During their life cycles,some species persist in an environ-mentally resistant cyst stage. They areconsidered to be about 10,000 to50,000 times more resistant to disin-fectant than are bacteria. Even water

treatment by filtration may not do thejob, since parasites such as Ciyp-tosporidium are small enough to passthrough filtration systems. Protozoaparasites are sometimes called the"super bug." Giardia and Cyp-tosporidium are the more commonlyknown waterborne protozoa.

The well-publicized Cyp-tosporidium outbreaks in Milwaukeeand Las Vegas serve as case studiesto document the inadequacy of estab-lished water treatment strategies. Thewater that sickened so many peoplehad been thoroughly treated, both dis-infected and filtered, in compliancewith all established treatment proce-dures and standards. Yet, pathogenicmicrobials obviously survived thetreatment process.

In their quest for improved watertreatment strategies, scientists aretesting different types of disinfectantsand combinations thereof, in effortsto find a treatment to removepathogenic protozoa. They also aretesting the use of ultraviolet light andozone. Also, efforts are being madeto improve the filtration process.Much work remains to be done.

If the removal of all waterbornepathogens is uncertain in a properlyoperating plant, the situation be-comes even more problematic if theoperational reliability of treatmentplants is questioned. And, in fact,questions about reliability of suchplants are arising. Operators are be-coming increasingly aware that watertreatment plants - as is true of allhuman-made systems - do notoperate at loo percent efficiency allthe time. Thus, it is not humanly pos-sìble to provide safe water at the tap100 percent of the time.

A properly operating water treat-ment system involves various opera-tions - flocculation, filtration and dis-infection - and the malfunctioning ofany one them can have possibleserious consequences to water con-sumers, especially since treatmentplants do not operate with back up

systems. If, for a brief period of time,a plant does not operate optimally,pathogenic organisms can enter acommunity's drinking water supply.Lab tests before the incident andafter may not detect the presence ofthe pathogens.

Such incidents may occur only afew times a year and result in waterconsumers' short-term exposure topathogens. However, unlike traceamounts of chemical contaminants,whose effects may become evidentonly after prolonged exposure, the ef-fects of microbial contaminants aremuch more immediate. After a one-time exposure, susceptible membersof a community can become seriouslyill.

San ildefonso potte,y design

In Holland, researchers studiedtreatment plant reliability by moni-toring a plant for the presence ofClostridium perfringens, a particularlyhardy bacteria that responds to watertreatment similar to Cyptosporidium.Monitoring the plant twice daily, theresearchers found that, although theplant was one of the country's finest,the clostridium bacteria passedthrough the plant, unaffected by treat-ment operations, three days of theyear. The researchers are not surewhy.

Water consumers at times mayhave a direct role in treatingmicrobial contaminated water. TheSafe Drinking Water Act requireswater systems serving more than 25

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people to test their water regularlyfor a wide variety of contaminants. Iftests indicate that levels of one ormore microbial contaminants exceedEPA standards, the utility issues aboil water alert, to put water users onnotice to either boil their water orrefrain from drinking it.

Boiling water then becomes thehome remedy, a low-tech, stove-topstrategy to rely on when the utility'scomplex water treatment processfails. Boiling water for about a minuteusually effectively removes microbialcontaminants. In 1995-1996, accord-ing to the EPA, approximately 1,400"Boil Water Alerts" were issues in 28states in response to local waterquality conditions. These alerts are in-tended as short-term remedies. Notonly is boiling water impractical forany large-scale application, but drink-ing it can cause nutritional andgastrointestinal disorders.

Source Protection

Becauseremoving waterborne

pathogens in the treatmentprocess poses various and formidableproblems, some officials stress the im-portance of protecting the watersource, whether lake, river or human-made reservoir, to limit and evenprevent contamination. They view thisprotection as an essential pre-treat-ment strategy. They advocatestrenuous measures to prevent humansewage and animal waste from wash-ing into surface water, whether fromcity, farm runoff or overflowingsewage treatment plants. For ex-ample, in many areas, cattle grazing iscarefully controlled and evenrestricted in drinking-water sourcewatersheds.

Rainfall can transport pathogensfrom contaminated watersheds tosource water and adversely affect itsquality. When studying climatic condi-tions and their effect on the occur-rence of waterborne disease, re-

searchers found that above normalrainfall events usually preceded majorwaterborne outbreaks from surfacewater supplies.

Conditions creating turbidity insource water seem especially tohave an adverse affect on microbialwater quality. A study in Philadelphiademonstrated that when turbidity ofsource water increased, more chil-dren were likely to be hospitalized fordiarrhea, with fewer children hospital-ized for the same cause when tur-bidity decreased. Test resultsdemonstrated that when turbiditylevels are high, increased pathogensare likely to be present in the waterand pass through the treatmentprocess, even if the water meets all es-tablished standards.

Swimming in the Reservoir

Concernfor the quality of source

water has prompted some utilitiesto limit or ban recreational uses ontheir reservoirs. Policies dealing withthis issue are adopted in various areasthroughout the world. For example,Australia takes a strict view of thematter and generally bans all recrea-tion on drinking water reservoirs. Inthe United States, various utilitieshave adopted different forms of thepolicy, from banning all recreationaluse to just disallowing body-contactrecreation; i.e., swimming or anyother recreational activity that resultsin human contact with the water. TheAmerican Water Works Association'sofficial position is that no body-con-tact recreation should be allowed indrinking water reservoirs.

Metropolitan Water District ofSouthern California (MWDSC) is inthe process of determining whether toallow full-body recreation on its new4,500 surface-acre, 800,000 acre-footeastside reservoir. Other kinds ofrecreational activities would be al-lowed on and around the lake, includ-ing fishing, boating, hiking and

equestrian activities. MWDSC doesnot presently allow full-body recrea-tion on any of its reservoirs.

To help decide the issue MWDSCcommissioned a scientific study todetermine the risk posed to drinkingwater quality by permitting full-bodyrecreation on reservoirs. Research onthe topic is limited, and the MWDSCstudy is considered ground-breakingwork. The study included construct-ing a mathematical model to predictthe occurrence of pathogens with in-creased recreational use. A result ofthe study determined that recreationwould significantly increase levels ofCiyptospondium and a broad range ofother pathogens in the reservoir.

For example, among its findingsthe research team determined a swim-mer or bather releases a tenth of agram of feces when entering thewater. This is called the fecal shed-ding rate. Infants could add sig-nificantly more. (When these facts areconsidered along with another figure,i.e., swimmers and waders may ingestfrom 0.3 to 1.7 ounces of water perouting, it becomes apparent that therecreational use of water also posesrisks to swimmers and waders.) Thiswould cause increased levels of Ciyp-tosporidium in the reservoir, Theutility's main concern is with Ciyp-tosporidium since this pathogen posesthe most treatment problems.

The utility worked out a scenarioto estimate additional treatment coststhat could result if full-body recrea-tion were allowed on the reservoir.The scenario anticipated future treat-ment regulations for Cyptosporidiumand applied them to treating reservoirwater after full-body recreation. Theincreased costs of ozonation were es-timated at $17 million to $90 millionin capital costs and $5 million in an-nual operations and maintenancecosts.

The MWDSC board has not yetdecided whether to allow full-bodyrecreation at the reservoir. The boardis awaiting the results of an economic

9

study that also is being done.Decisions affecting the recreation-

al use of a body of water will undoub-tedly have economic implications,and this is a major considerationwhen deciding the issue. Further, adecision to restrict recreational ac-tivities at the eastside reservoir couldaffect how other reservations in thestate are managed. It is an emergingwater issue in California.

In Arizona, drinking water sourcesgenerally are open to varied recrea-tional uses including full-body recrea-tion. For example, recreation is un-restricted in the reservoirs main-tained by the Salt River Project,which provides drinking water to thePhoenix area. Also, advocates forbuilding a Central Arizona Projectterminal storage reservoir in the Tuc-son Mountains bolstered their posi-tion by claiming the facility would bean attractive recreational site. Therecreational use of CAP water, how-ever, is not the issue with many Tue-sonans; whether they should drinkCAP water is the overriding issue.

GroundwaterContamination

jike surface water, groundwater,4once thought to be relatively pris-

tine, also can contain microbialpathogens. Its natural storage in anunderground aquifer is no assurancethat it is free of microbial contamina-tion. The leaking of raw materialsfrom septic systems and sewer linescan contaminate groundwater.

At present, no federal regulationsexist requiring the disinfection ofgroundwater wells that are sources ofpublic water supplies. In contrast, sur-face water supplies are strictly regu-lated. With regards to disinfection ofgroundwater, a patchwork patternprevails, with some states requiringgroundwater disinfection and othersnot. Meanwhile some water suppliersof groundwater may disinfect, al-

though not required by state orfederal laws,

In response to the situation, EPAis in the process of adopting a"Groundwater Disinfection Rule." Aspart of the rule-making process, theagency is conducting a nationwidestudy to determine the extent ofgroundwater contamination, to betterdetermine appropriate rules andregulations. The study thus far has in-dicated that half the groundwater con-sumed as drinking water in theUnited States is not disinfected.

The study also has shown that be-tween 10 and 40 and possibly even 50percent of the wells have ground-water contaminated with microbes.The rather broad range reflects dif-ferent methods of testing to deter-mine contaminants in groundwater.The higher figures are the result ofusing a technique called polymerasechain reaction (PCR). PCR indicateswhether a well was at one time con-taminated, but not whether theviruses are active and represent a cur-rent public health problem. Somecritics believe PCR provides an in-flated figure. Others say that PCRshows whether the potential for viralcontamination is present, and itsresults deserve careful attention.

The microbial pathogens mostcommonly found in groundwaterwells are viruses, from sewage dis-charge or human fecal material. Thesource is readily apparent sincehumans are the only significantsource of waterborne viral pathogens.Viruses are smaller than otherpathogens and can pass through soilto enter the aquifer. Protozoa such asGiardia and Ciyptosporidium are lesslikely to be found in groundwaterwells, They are sufficiently large to befiltered by the soil and removed.Protozoa that are found in ground-water are the likely result of a directinfusion of contaminated surfacewater into the aquifer; e.g. when frac-tured rock acts as a conduit for waterto enter an aquifer.

Detected concentrations ofpathogens in groundwater have notbeen sufficiently large to cause largeoutbreaks of waterborne illness. Themore likely result has been a patternof occasional outbreaks among in-dividuals, with no discernable patternto report to public health officials.

Although called "GroundwaterDisinfections Rule," the impendingEPA regulations have a broader in-tent than just groundwater disinfec-tion. More broadly, the purpose ofthe regulations is to protect the publicfrom fecal contamination in wellwater. Disinfection is one strategy.Other strategies include eliminatingsources of contamination.

In its efforts to develop and imple-ment groundwater disinfection rulesEPA is aware of the financial burdenfederal mandates can impose onsmall water providers. As a result,EPA plans to carefully definegroundwater disinfection require-ments to ensure they will be appliedonly in situations thoroughly warrant-ing their use. The Groundwater Disin-fectant Rules are to be proposed inMarch 1999.

Regulationsecent changes in drinking wateregulations reflect increased offi-

cial concern with microbial contam-inants. When the 1974 Safe DrinkingWater Act (SDWA) was reauthorizedin 1986, the priority then was toreduce chemical contaminants indrinking water to lessen a possiblecancer risk. At that time, Congressdirected the Environmental Protec-tion Agency to establish standards for25 new contaminants every threeyears.

In 1996, the SDWA was againreauthorized, but with a differentwater quality emphasis. In the inter-im, between the 1986 and 1996reauthorizations, water and health of-ficials took a careful look at the long-

lo

term risk of cancer vs. the more imme-diate risk of microbial waterborne dis-ease. They decided that microbialcontaminants such as Ciyp-tosporidium and Giardia posed thehighest potential drinking water riskto human health. As a result, the 1996amendments refocused EPA's com-mitment of setting standards for "25contaminants every 3 years" to a con-cern with microbial contaminants.

The 1996 SDWA amendments alsoaddressed concerns about certain dis-infectants and their byproducts indrinking water. In use since the earlypart of this century, chlorine, whenused to treat microbes, was found toproduce byproducts possibly hazard-ous to human health. Evidence ex-isted that such byproducts might in-crease the risk of cancer as well as ad-verse developmental effects.

Officials thus faced a dilemma. Suf-ficient amounts of disinfectant needto be applied to reduce the hazards ofmicrobial contaminants, without atthe same time unduly raising risks as-sociated with disinfection byproducts.Disinfectants have little effect onciyptosporidium but they are effec-tive against other disease-causingmicrobes. If disinfectants, thepredominant purifying treatmentused by almost all systems, are re-duced to lessen hazardous bypro-ducts, a risk is run of spreading water-borne diseases. An appropriaterisk/benefit tradeoff needs to beworked out.

In response to this issue, the 1996amendments directed EPA todevelop rules dealing with disinfec-tant byproducts or DBPs. EPA estab-lished a regulatory negotiation com-mittee to develop DBP standards.The committee decided more infor-mation was needed before developingfinal microbial and DBP rules and ac-cordingly recommended an extensivenational information collection effort.An Information Collection Rule waspromulgated in May 1996.

The rule requires that drinking

water supply systems serving over100,000 persons collect and report in-formation on the presence and levelsof microbial contamination and disin-fectant byproducts. They also are toreport on the effectiveness of varioustreatment technologies to reducethose levels. Further, utilities are tomonitor for representative bacteria,viruses, and protozoan parasites overan 18-month period. National es-timates then can be made of thepresence and levels of microbial con-tamination in water entering watertreatment plants. Utilities also are tomonitor for a number of parametersrelated to disinfection byproducts.For example, they are to monitor fororganic materials present in waterentering water treatment plants. Suchmaterials react with disinfectants toform byproducts.

Collected information will be usedto determine appropriate modifica-tions of current regulations onmicrobial contamination and to deter-mine the need for further rules. Forexample, the information is expectedto provide EPA with the data neededto set future standards for microbialcontaminants. The data collection in-volves about 500 treatment plants andis expected to cost about $130 million,to be expended over a three periodbeginning in 1997. The schedule callsfor the promulgation of a Interim En-hanced Surface Water TreatmentRule and a Stage 1 DBP Rule byNovember 1998.

Also in response to the 1996SDWA amendments, EPA is develop-ing a Drinking Water ContaminantCandidate List. The October 6, 1997Federal Register published a draft ofthis list to be finalized in early 1998.Listed contaminants are those thatare known or anticipated to occur inpublic water systems. The final listingwill determine priorities for research,guidance, and possible regulation.The list includes 13 microbiologicalcontaminants.

A Global Affliction

arious issues are more frequentlybeing viewed in a global context;

e.g., global warming, the globaleconomy and the global reach of theinformation revolution. The problemof microbial pathogens in drinkingwater also might be seen in a globalperspective. To view it as a problemaffecting all nations of the world, bothdeveloped and developing countries,is not of course to suggest that all na-tions are equally affected. Because ofpublic health advantages, developednations do not suffer the ravages thatdeveloping countries experience frommicrobially-infected drinking water.

San Ildefonso pottery design

A recent United Nation's reportportrays a grim picture of waterquality conditions in some developingcountries. The report states thatabout 80 percent of all diseases andover one-third of deaths in develop-ing countries are the result of peopleconsuming contaminated water. Notonly are the diseases debilitating, butthey also consume valuable time, withabout one-tenth of each person'sproductive time sacrificed to water-re-lated diseases. Further, diarrheakilled over 20 million children indeveloping nations in the last decade.The UN estimates that one in threepeople in the developing world iswithout safe drinking water and safesanitation. Human excreta and

11

sewage are identified as the majorcauses of water quality deteriorationin developing nations.

The effect of such statistics cantruly be numbing. The developed na-tions with their relatively high publichealth standards do not suffer thiskind of tragedy. Yet reasons for con-cern still exist. Dr. Rita Colwell, chair-person of the American Academy ofMicrobiology said, "Microbiologicallysafe drinking water can no longer beassumed, even in the United Satesand other developed countries, andthe situation will worsen unlessmeasures are taken in the immediatefuture. The crisis is global."

Awareness is the key. If people indeveloped nations, because of an in-creased concern about microbialpathogens in their drinking water, ac-quire a keener awareness of the waterproblems of developing countries,possibly a profounder understandingof water quality could arise. Safedrinking water might then becomemore than a public health goal. Ourshared humanity with all otherpeoples of the world, from developedand developing nations, might berecognized in the global effort to en-sure supplies of safe drinking water.

Conclusion

pathogenicmicrobes are increasing-

ly in the news lately, with accountsof tainted meat, infected vegetablesand contaminated water appearingfairly regularly. Such a story recentlyappeared in "Parade Magazine,"America's weekly reader. ItsFebruary 8 edition ran a story titled,"Before the Next Epidemic Strikes."The article posed the question:"What grave threats to our nation'shealth are looming on the horizon?"

In a way, the story of microbesmakes good media copy, with made-to-order elements to attract wide andpopular attention. For one, microbesare invisible. Threats from unseen

dangers convey a sense of drama,even mystery. Also, microbes, by in-fecting our food and water, pose apersonal threat, a danger to hearthand home. Microbes also representan ongoing story, awaiting futurescientific discoveries and, unfor-tunately, further incidents of diseaseand death.

The headlines for an article aboutCiyptosporidium in the Phoenix "NewTimes" exploited the issue for itsdramatic appeal. The article wastitled, "Tale of the Crypto," an ob-vious reference to "Tale of theCrypt." A subhead further preparedreaders: "lt's called crypto and it cankill." (The article was far better thanits headlines.)

More than other water issues, themicrobial threat to drinking water isbeing deemed newsworthy, with allthe advantages and disadvantages ofthat designation. Interested citizenswill have more information availableto them, but may need to develop acritical or independent judgement toensure a proper perspective on the

TFIÍ UNVFRÇITYF

ARIZÖÑATUCSON ARI/ONA

ARROYOThe University of ArizonaWater Resources Research Center350 N. CampbellCollege of AgricultureTucson, Arizona 85721

WRRCWater Resources Research Center

issue. Especially useful when the issueis microbial water quality, criticaljudgement is, in fact, a tool worth cul-tivating to better understand all wateraffairs.

The author thanks all the peopleand organizations contributing infor-mation to this newsletter, especiallythe following: Carlos Enriquez,Chuck Gerba, Ian Pepper, Kelly

Water Resources Research Center Advisory Committee

Phil Briggs, Geraghty and Miller, Inc.William Chase, City of PhoenixHerb Dishlip, Arizona Department

of Water ResourcesChuck Huckeiherry, Pinza countyDavid C. Iwanski, Apri -Business

council ofA rizan a

John L. Keane, Salt River ProjectLois Kulakowski, Southern Arizona

Water Resources AssociationJohn Lewis, inter-Tribal CouncilFloyd Marsh, City of ScottsdaleMichael McNulty, Brown & Bain

Reynolds, University of Arizona; Her-man Bouwer, U.S. Water ConservationLab; Joan Rose, University of SouthFlorida; Bruce Macler, U.S. Envi ron-mental Protection Agency; MarkBeuler, Mie Stewart, MetropolitanWater District of Southern California.The ideas and opinions expressed inthe newsletter do not necessarilyreflect the views of any of the abovepeople or organizations.

Nick Meicher, U.S. G.SErrol L. Montgomery, Errol L.

Montgomeiy & AssociatesDouglas C. Nelson, Arizona Rural

WaterAssociationRobert O'Leary, Water Utilities

Association of ArizonaEd Sadler, Arizona Department ofEnvironmental QualityDavid "Sìd" Wilson, Central Arizona

Water Conservation DistrictDon W. Young,Arizona Attorney

General's Office

The contents of this publication do not necessarily reflect the views or policies oany of the above individuals or organizations.

NON-PROFIT ORG.US POSTAGE

PAIDTUCSON, ARIZONA

PERMIT NO. 190