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Drinking Water Contamination AOEC Teaching Module 2007.

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Drinking Water Contamination AOEC Teaching Module 2007
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Drinking Water Contamination AOEC Teaching Module 2007 Slide 2 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 for Toxic 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,(210)567-7407. Slide 3 2 Introductory case studies Examples of specific toxicants Farm chemicals Perchlorate Heavy Metals Biologicals Clinical problem solving Outline Slide 4 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 Slide 5 Case Study #1 Introduction to the Problem From March 23rd to April 5th, 1993 two water treatment facilities in Milwaukee reported record setting turbulence in intake water April 5 th the Department of Health reported an outbreak of gastrointestinal illness Slide 6 Southern Water Treatment Plant Slide 7 Mac Kenzie W et al. N Engl J Med 1994;331:161-167 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 Slide 8 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 Slide 9 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 Slide 10 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 Slide 11 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 Slide 12 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 Slide 13 Hebbronville, TX Slide 14 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 g/L Prior to 2006, the maximum contaminant level for As was 50 g/L Home of the Hebbronville Longhorns Slide 15 Evaluation of Population 2/3 of the 140 people sampled had urinary inorganic As concentrations > reference concentration of 10 g/L Drinkers of tap water had higher-than- reference range levels Drinkers of bottled water had substantially lower levels. Hebbronville Courthouse Slide 16 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 g As per serving of rice 20-24 g As per serving of beans (if cooked in water containing 50 g/L) Slide 17 Actions Recommended in Hebronnville Those with inorganic As levels > 20 g/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. Slide 18 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 Slide 19 Bangladesh Borders India and Burma Local water wells were commonly contaminated with disease-causing microorganisms Slide 20 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 < 200 meters in depth Resulted in high levels of arsenic in soil leached into water, first confirmed in 1993 Slide 21 Quantification of Arsenic Exposure In 1980s first reports of arsenic-related dermatologic disease Analysis of water in British Geological Survey showed that >35% of wells contained > 50 g As/L In some districts >80% of wells contained greater than 50 g As/L 8% had As concentrations of > 300 g/L Slide 22 % of Field-tests positive for As Slide 23 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 Slide 24 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 Slide 25 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? Slide 26 TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS Farm chemicals Perchlorates Solvents Arsenic Microbiological Agents Slide 27 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 Slide 28 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 >8,000 wells had levels exceeding 10 ppm 1-2% of population estimated to be exposed to excessive levels of nitrates >600,000 homes draw from contaminated wells and rural wells are not routinely tested Slide 29 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 Slide 30 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 Slide 31 Methemoglobinemia Treatment Supportive care Removal from exposure Reducing agents such as methylene blue Antioxidants such as vitamin C Slide 32 TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS Farm chemicals Perchlorates Solvents Arsenic Microbiological Agents Slide 33 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 Slide 34 Perchlorates Perchlorates are the primary oxidizers in solid rocket fuel Perchlorates are also very stable in water Slide 35 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 Slide 36 Exposure Exposure pathways may include: Drinking contaminated water Also may occur through tobacco use Proximity to industrial use of perchlorates Slide 37 Perchlorate Contamination In 1997 perchlorates were discovered in drinking water Primarily affects Western States Environmental Science and Technology/News May 1, 1998 Slide 38 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 Slide 39 TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS Farm chemicals Perchlorates Solvents Arsenic Microbiological Agents Slide 40 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. Slide 41 Potential Exposure Pathways Possible ingestion of MTBE in water Concentration dependant Dermal exposure while showering or swimming Medically important systemic absorption is unlikely Slide 42 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 Slide 43 Water Purity Standards EPA recommends < 4 mg MTBE/Liter State-specific limits exist Taste/odor threshold is 20-40 ppb Slide 44 TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS Farm chemicals Perchlorates Solvents Arsenic/Heavy Metals Microbiological Agents Slide 45 Heavy Metal Occurrence Mostly natural Mineral deposits Natural soil constituents Increased levels may exist at some industrial sites Slide 46 Potential Exposure Pathways Contaminated water supply Food grown in contaminated soil or with contaminated water Slide 47 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 Slide 48 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 Slide 49 TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS Farm chemicals Perchlorates Solvents Arsenic Microbiological Agents Slide 50 Microbiological Water Contamination Several broad categories, including: Bacterial Protozoa Viruses Slide 51 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 Slide 52 Travellers Diarrhea Caused by infectious agents Primarily Escherichia coli Produces enterotoxins Watery diarrhea lasting several days E.coli 0157:H7 Slide 53 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 Slide 54 Treatment Usually self-limited Only symptomatic treatment usually required Antibiotics (sulfa drugs, quinolones) may slightly reduce duration of illness Slide 55 Dysentery Enteroinvasive disease caused by any of several organisms Salmonella, Shigella, Campylobacter Bloody mucoid diarrhea with fever, fecal leukocytes Antibiotic treatment recommended Salmonella infantis Slide 56 Protozoan Infections Slide 57 Protozoal Infections Common cause of endemic diarrheal illness Typically spread through fecal-oral transmission Common types include Cryptosporidium Giardia Slide 58 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 Slide 59 Chen X et al. N Engl J Med 2002;346:1723-1731 Life Cycle of Cryptosporidium and Infection of Host Epithelial Cells Slide 60 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 Slide 61 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 Slide 62 Viral Diseases Multiple viral pathogens Rotaviruses Hepatitis A Enteroviruses Most common epidemic (not endemic) diarrheal illnesses No specific treatment Slide 63 Norwalk Virus Common cause of epidemic diarrheal illness Responsible for recent outbreaks on cruise ships Slide 64 Prevention Hygiene Reduce fecal-oral transmission Hand-washing Sanitization of surfaces Vaccination Effective for hepatitis A prevention Slide 65 Reported Cases of Hepatitis A, United States 1995: Vaccine Licensed 1996: ACIP recommendations 1999 ACIP recommendations Source: NNDSS, CDC Slide 66 Rate > 20/100,000 Rate 10-20/100,000 Rate < 10/100,000 States with Hepatitis A Rates > 10/100,000 1987-97 Slide 67 Number of years that Reported Incidence of Hepatitis A Exceeded 10 Cases per 100,000, by County, 1987-1997 Slide 68 Hepatitis A Incidence, United States 2002 incidence 1987-97 average incidence > = 20 10 - 19 5 - 9 0 - 4 Rate per 100,000 Slide 69 Thielman N and Guerrant R. N Engl J Med 2004;350:38-47 Approach to the Evaluation and Management of Infectious Diarrhea Slide 70 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 Slide 71 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) Slide 72 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 Slide 73 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) Slide 74 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 Slide 75 Investigation Comparing geographical distribution of patients to water distribution plans reveals that areas affected all receive water from same reservoir and treatment plant. Slide 76 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 Slide 77 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 Slide 78 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 Slide 79 References http://www.atsdr.cdc.gov/hac/pha/hebbr onville/hae_p1.html#sum http://www.atsdr.cdc.gov/hac/pha/hebbr onville/hae_p1.html#sum 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 Slide 80 References American Academy of Pediatrics. 1970. Policy statement. Infant methemoglobinemia: the role of dietary nitrate. Pediatrics 46(3):475-8 Slide 81 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; 346:1723-1731, May 30, 2002. Thielman NM, Guerrant RL. Acute Infectious Diarrhea. N Engl J Med 2004; 350:38-47, Jan 1, 2004