Drinking Water Contamination

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Drinking Water Contamination

• AOEC Teaching Module
• 2007

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This educational module was produced by Michael
Greenberg, MD, MPH, Arthur Frank, MD, PhD, and
John Curtis, MD for The University of Texas
Health Science Center at San Antonio (UTHSCSA)
Environmental Medicine Education Program and
South Texas Environmental Education and Research
Program (STEER-San Antonio/Laredo/Harlingen,Texas)
Administrative support was provided by the
Association of Occupational and Environmental
Clinics through funding to UTHSCSA by the Agency
forToxic Substances and Disease Registry
(ATSDR), U.S. Department of Health and Human
Services.Use of this program must include
acknowledgement of the authors,UTHSCSA and the
funding support.For information about other
educational modules contact the UTHSCSA STEER
office, Mail Code 7796, 7703 Floyd Curl Drive,
San Antonio,Texas 78229-3900,[phone].
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Outline

• 2 Introductory case studies
• Examples of specific toxicants
• Farm chemicals
• Perchlorate
• Heavy Metals
• Biologicals
• Clinical problem solving

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Objectives

• After completion of this module, the student will
  be able to
• Describe the importance of the water supply as it
  relates to epidemic illness
• Identify issues related to water purity as
  related to the use of industrial and agricultural
  chemicals
• Demonstrate ability to evaluate illness due to
  biological contamination of water

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Case Study 1Introduction to the Problem

• From March 23rd to April 5th, 1993 two water
  treatment facilities in Milwaukee reported record
  setting turbulence in intake water
• April 5th the Department of Health reported an
  outbreak of gastrointestinal illness

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Southern Water Treatment Plant
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Maximal Turbidity of Treated Water in the
Northern and Southern Water-Treatment Plants of
the Milwaukee Water Works from March 1 through
April 28, 1993
Mac Kenzie W et al. N Engl J Med 1994331161-167
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Mystery GI Illness

• 50 of the population served by the southernmost
  plant and 25 of those served by the northern
  plant become ill
• Over 400,000 (26 of population) estimated to be
  affected
• GI illness
• Watery diarrhea lasting approximately 9 days
• Low grade fever
• Average 10 lbs. weight loss

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Investigation

• Cryptosporidium was identified in over 600 stool
  samples (30 of those tested)
• No other causative organisms found in greater
  than 2 of samples
• Later, Cryptosporidium was also found in ice made
  from water during that period

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Cryptosporidium in water

• Disease transmitted by oocysts
• Not destroyed by chlorine or chloramine
• Difficult to identify and not normally screened
  for by water treatment facilities
• Disease is usually self-limited in
  immunocompetent hosts

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Illustrative Points

• Importance of evaluating air, water, and food
  supply in epidemic illness
• Relevant history regarding event
• Symptoms, evaluations of patients
• Impact on water-quality standards
• Impact on U.S. public health including impact on
  HIV/AIDS awareness

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Case Study 2

• In January of 2003, a resident of Hebbronville,
  TX contacted the Texas Department of Health
  concerned about elevated arsenic (As) levels in
  drinking water

Hebbronville Library
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Hebbronville, TX
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Hebbronville

• Agency for Toxic Substances and Disease Registry
  (ATSDR) conducted an evaluation of local
  residents and water supply
• Water supply
• Arsenic levels in the drinking water ranged from
  43.7 to 52.1 µg/L
• Prior to 2006, the maximum contaminant level for
  As was 50 µg/L

Home of the Hebbronville Longhorns
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Evaluation of Population

• 2/3 of the 140 people sampled had urinary
  inorganic As concentrations gt reference
  concentration of 10 µg/L
• Drinkers of tap water had higher-than-reference
  range levels
• Drinkers of bottled water had substantially lower
  levels.

Hebbronville Courthouse
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Evaluation of Population

• According to the ATSDR 91 of the population
  described themselves as Hispanic
• Typical regional diet included rice and beans
  cooked in water - potentially increasing arsenic
  consumption
• 8-9 µg As per serving of rice
• 20-24 µg As per serving of beans
• (if cooked in water containing 50 µg/L)

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Actions Recommended in Hebronnville

• Those with inorganic As levels gt 20 µg/g of
  creatinine to be retested
• Individuals encouraged to discuss their results
  with a personal health care provider
• Evaluation of other (dietary) sources of As
• Efforts to reduce As levels in the public water
  system.

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Implications

• Unclear what, if any, health effects would be
  expected
• Possible parallels to areas such as Taiwan and
  Bangladesh that have experienced high levels of
  environmental arsenic

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Bangladesh

• Borders India and Burma
• Local water wells were commonly contaminated with
  disease-causing microorganisms

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Bangladesh Water Supply

• UNICEF and other international organizations
  promote the use of tube wells for safer water
  supply in the 1970s and 1980s
• Thin tubes sunk in ground usually lt 200 meters
  in depth
• Resulted in high levels of arsenic in soil
  leached into water, first confirmed in 1993

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Quantification of Arsenic Exposure

• In 1980s first reports of arsenic-related
  dermatologic disease
• Analysis of water in British Geological Survey
  showed that gt35 of wells contained
• gt 50 ?g As/L
• In some districts gt80 of wells contained greater
  than 50 ?g As/L
• 8 had As concentrations of
• gt 300 ?g/L

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of Field-tests positive for As
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Chronic Arsenic Toxicity

• Approximately 125 million residents drawing from
  water supply
• In some studies 30-50 of patients had skin
  lesions due to arsenic
• Skin lesions typically develop after latency of
  10 years

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Public Health Implications

• Other potential long-term effects of arsenic
  exposure
• Cancers, including skin, bladder, kidney and lung
• Neurological effects
• Hypertension, vascular disease
• Pulmonary disease
• Diabetes

Environmental Health Perspectives Volume 110,
Number 2, February 2002
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Public Health Issues - Bangladesh

• How to treat the millions of exposed patients?
• Nutritional supplementation?
• Infected hyperkeratotic lesions?
• What about tremendous predicted expense from
  excess cancer morbidity/mortality?

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TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS

• Farm chemicals
• Perchlorates
• Solvents
• Arsenic
• Microbiological Agents

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Occurrence of Nitrite/Nitrate

• Naturally occurring inorganic ions
• Enter groundwater from fertilizer use, including
  anhydrous ammonia
• Releases totaled over 110 million pounds
• Contamination from septic systems
• Chemical characteristics lead to migration to
  ground water

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Exposure

• Groundwater supplies 20 of nitrate intake, but
  can be higher in the setting of water
  contamination
• MCL for nitrates has been set at 10 ppm, and for
  nitrites at 1 ppm
• US Geological survey in 1995 showed gt8,000 wells
  had levels exceeding 10 ppm
• 1-2 of population estimated to be exposed to
  excessive levels of nitrates
• gt600,000 homes draw from contaminated wells and
  rural wells are not routinely tested

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Health Effects

• Nitrites and nitrates cause oxidation
• Nitrates are converted in vivo to nitrites
• More potent oxidizers
• Oxidation of iron in hemoglobin results in
  methemoglobinemia

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Methemoglobinemia

• Oxidized hemoglobin unable to carry oxygen
  effectively
• Infants at risk due to
• Increased levels of fetal hemoglobin
• Reduced levels of methemoglobin reductase
• One cause of infantile cyanosis or Blue-baby
  syndrome
• Has resulted in numerous infant deaths

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Methemoglobinemia Treatment

• Supportive care
• Removal from exposure
• Reducing agents such as methylene blue
• Antioxidants such as vitamin C

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TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS

• Farm chemicals
• Perchlorates
• Solvents
• Arsenic
• Microbiological Agents

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Perchlorates

• Naturally occurring (e.g. in saltpeter deposits)
• Magnesium, potassium, sodium, lithium, ammonium
  perchlorate are manufactured in large amounts
• Uses include solid rocket fuel, ammonium
  perchlorate, explosives

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Perchlorates

• Perchlorates are the primary oxidizers in solid
  rocket fuel
• Perchlorates are also very stable in water

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Exposure

• EPA reports that 40 of 1547 National Priority
  Sites contain perchlorates
• Leaves soil to enter water
• May persist for years
• No proven method for removal from water

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Exposure

• Exposure pathways may include
• Drinking contaminated water
• Also may occur through tobacco use
• Proximity to industrial use of perchlorates

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Perchlorate Contamination

• In 1997 perchlorates were discovered in drinking
  water
• Primarily affects Western States

Environmental Science and Technology/News May 1,
1998
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Health Effects

• Perchlorates effect the thyroid
• Interferes with the thyroids ability to take up
  iodide
• Clinical relevance is unclear
• Human studies generally report insufficient
  evidence to determine risk of carcinogenesis

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TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS

• Farm chemicals
• Perchlorates
• Solvents
• Arsenic
• Microbiological Agents

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Solvents - including MTBE

• Methyl-t-butyl-ether
• Manufactured by reaction of methanol and
  isobutylene
• Flammable liquid with disagreeable odor
• Evaporates quickly
• Added (like ethanol) to gasoline as an oxygenator
  to decrease carbon monoxide emissions.

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Potential Exposure Pathways

• Possible ingestion of MTBE in water
• Concentration dependant
• Dermal exposure while showering or swimming
• Medically important systemic absorption is
  unlikely

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MTBE - possible health effects

• Any adverse effects are expected to be a function
  of exposure and dose
• Vapor exposure (at high concentration for
  prolonged periods) may have mild but reversible
  effects
• Ingestion
• Potential cancer risk is unproven
• Not classified by the IARC
• Only weak evidence of carcinogenicity in some
  animal studies

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Water Purity Standards

• EPA recommends lt 4 mg MTBE/Liter
• State-specific limits exist
• Taste/odor threshold is 20-40 ppb

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TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS

• Farm chemicals
• Perchlorates
• Solvents
• Arsenic/Heavy Metals
• Microbiological Agents

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Heavy Metal Occurrence

• Mostly natural
• Mineral deposits
• Natural soil constituents
• Increased levels may exist at some industrial
  sites

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Potential Exposure Pathways

• Contaminated water supply
• Food grown in contaminated soil or with
  contaminated water

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Potential Health Effects - Arsenic

• Acute
• Possible GI illness, neuropathy
• Uncommon from environmental exposure
• Intentional exposures
• Suicidal
• Homicidal
• Chronic
• Dermatologic, vascular and malignant disease
• Environmental exposure
• Bangladesh

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Treatment for Arsenic/Metals

• For chronic exposure the treatment is REMOVAL
  FROM EXPOSURE
• For acute exposure, consultation with a Poison
  Control Center or medical toxicologist is
  advisable
• Chelation may be considered in some extreme cases

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TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS

• Farm chemicals
• Perchlorates
• Solvents
• Arsenic
• Microbiological Agents

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Microbiological Water Contamination

• Several broad categories, including
• Bacterial
• Protozoa
• Viruses

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Bacterial Contamination

• Travellers diarrhea
• Up to 50 of international travelers may be
  afflicted depending on region
• Approximately 10 million people
• High-risk areas
• Latin/Central America
• Africa
• Middle-East
• Asia

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Travellers Diarrhea

• Caused by infectious agents
• Primarily Escherichia coli
• Produces enterotoxins
• Watery diarrhea lasting several days

E.coli 0157H7
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Travellers Diarrhea

• Prevention
• Avoidance of local waters and ice
• Bottled water for consumption
• Daily bismuth (e.g.Pepto-Bismol) preparations
• Avoidance of strong antacids (PPIs)
• Possibly prophylactic antibiotics for select
  patients

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Treatment

• Usually self-limited
• Only symptomatic treatment usually required
• Antibiotics (sulfa drugs, quinolones) may
  slightly reduce duration of illness

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Dysentery

• Enteroinvasive disease caused by any of several
  organisms
• Salmonella, Shigella, Campylobacter
• Bloody mucoid diarrhea with fever, fecal
  leukocytes
• Antibiotic treatment recommended

Salmonella infantis
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Protozoan Infections
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Protozoal Infections

• Common cause of endemic diarrheal illness
• Typically spread through fecal-oral transmission
• Common types include
• Cryptosporidium
• Giardia

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Cryptosporidium parvum

• Worldwide presence in water supply
• Not effectively killed by chemical purification
  methods
• Prevention through
• Boiling of drinking water
• Water filtration with 1 micron pores

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Life Cycle of Cryptosporidium and Infection of
Host Epithelial Cells
Chen X et al. N Engl J Med 20023461723-1731
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Cryptosporidium - Health Effects

• Watery diarrhea lasting 1-2 weeks in normal hosts
• May result in dehydration, weight-loss
• Usually self-limited, but may be severe in
  immunocompromised hosts
• Treatment includes anti-retrovirals for those
  with HIV
• Possible role for nitrazoxanide

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Giardia Lamblia

• Very common parasitic disease
• More common in warmer climates
• Prevention is similar to measures for
  cryptosporidium
• Boiling of water
• Filtration
• Reverse osmosis
• 1 micron pores

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Viral Diseases

• Multiple viral pathogens
• Rotaviruses
• Hepatitis A
• Enteroviruses
• Most common epidemic (not endemic) diarrheal
  illnesses
• No specific treatment

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Norwalk Virus

• Common cause of epidemic diarrheal illness
• Responsible for recent outbreaks on cruise ships

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Prevention

• Hygiene
• Reduce fecal-oral transmission
• Hand-washing
• Sanitization of surfaces
• Vaccination
• Effective for hepatitis A prevention

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Reported Cases of Hepatitis A, United States
1995 Vaccine Licensed
1996 ACIP recommendations
1999 ACIP recommendations
Source NNDSS, CDC
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States with Hepatitis A Rates gt 10/100,000 1987-97
Rate gt 20/100,000
Rate 10-20/100,000
Rate lt 10/100,000
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• Number of years that Reported Incidence of
• Hepatitis A Exceeded 10 Cases per 100,000,
• by County, 1987-1997

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Hepatitis A Incidence, United States
1987-97 average incidence
2002 incidence
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Approach to the Evaluation and Management of
Infectious Diarrhea
Thielman N and Guerrant R. N Engl J Med
200435038-47
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Water as a Terrorist Target

• Watersheds and reservoirs contain a centralized
  depot of an essential resource for large numbers
  of people
• Often inadequately protected
• Impossible to monitor for all possible pathogens
  at all times

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Prevention of Water Terrorism

• Certain chemical properties of water are
  monitored continuously
• Very large volume of water
• Would require very large amounts of toxins to
  reach harmful levels
• Attractive terrorism agents would have to be
  extraordinarily potent to be effective (such as
  botulinum toxin)

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Clinical Problem Solving

• 40 patients present over a 2-3 day period with GI
  illness
• Watery diarrhea
• Crampy abdominal pain
• No fever/vomiting
• No occupational, social, or family connection
  between most patients

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Key Physician Actions

• Recognize cluster of illnesses
• Try to find shared exposure
• Attendance at a gathering
• Family/workplace picnic etc.
• Eating at same restaurant or similar unusual
  foods
• Face-to-face contact (same school, workplace)

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Observations

• Some hospitals receive many more patients than
  others
• Most patients come from same geographic area
• No particular meals, restaurants, or workplaces
  occur with greater than expected frequency

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Investigation

• Comparing geographical distribution of patients
  to water distribution plans reveals that areas
  affected all receive water from same reservoir
  and treatment plant.

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Role of Community Physician

• Physicians are on the front-line
• They are the interface between the public and the
  public health agencies
• Therefore, physicians must treat not only
  individual patients, but be vigilant to protect
  and treat their entire community

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Key Physician Actions

• Recognition of illness cluster
• Recognition of probable environmental illness
• Development of rational evaluation and treatment
  options
• Reporting responsibilities
• Contact the CDC and local public health officials

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Treatment and Disposition of Patients

• Evaluate and resuscitate as necessary
• Identify and treat dehydration
• Check stool for blood and/or fecal leukocytes to
  screen for enteroinvasive disease (dysentery)
• Symptomatic treatment
• Obtain stool cultures, send stool for evaluation
  for ova and parasites

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References

• http//www.atsdr.cdc.gov/hac/pha/hebbronville/hae_
  p1.htmlsum
• Agency for Toxic Substances and Disease Registry.
  2001. Case studies in environmental medicine
  taking an exposure history. Atlanta US
  Department of Health and Human Services

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References

• American Academy of Pediatrics. 1970. Policy
  statement. Infant methemoglobinemia the role of
  dietary nitrate. Pediatrics 46(3)475-8

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References

• U.S. EPA. Integrated Risk Information System
  Perchlorate and Perchlorate Salts. 2/18/2005
• U.S. EPA. Assessment Guidance for Perchlorate.
  January 26, 2006
• Chen X.-M. et al. Current Concepts
  Cryptosporidiosis. N Engl J Med 2002
  3461723-1731, May 30, 2002.
• Thielman NM, Guerrant RL. Acute Infectious
  Diarrhea. N Engl J Med 2004 35038-47, Jan 1,
  2004