Methyl Tert-Butyl Ether Contamination in School Water System and Residential Wells
LINCOLN ELEMENTARY SCHOOL
DEMOTTE, JASPER COUNTY, INDIANA
In April 2002, methyl tert - butyl ether (MTBE), a chemical commonly found in commercialautomobile gasoline, was detected in the well water that supplies the Lincoln Elementary School inRoselawn, Indiana. The Indiana Department of the Environmental Management (IDEM) conducteda site visit, performed sampling of this and other selected areas surrounding the school, includinga gasoline station located near the school. IDEM then requested that the Indiana State Departmentof Health (ISDH) review existing data from the site and evaluate the public health implications ofcontamination at the school and surrounding neighborhoods. ISDH and IDEM provided informationto the community during a public availability session in May 2002.
Lincoln Elementary School is located in Roselawn, Indiana, but its mailing address is 10280 North450 East, DeMotte, Indiana. Roselawn and DeMotte are both located in Newton County. The schoolis approximately 1/4 mile north of Highway 10. The school has a current enrollment of approximately450 children, which includes grades kindergarten through six. The school grounds consist of a schoolbuilding and two little league fields. The fields are no longer used. An above-ground sanitary sewertreatment system used by the school is located approximately 1/4 mile north of the property.
The school is situated on approximately 14 acres of land. Residential properties are east of theschool, across the street. No creeks, streams, or ponds are on the property. No industrial sites arelocated near the school. A church and an adult/child day care center (The Generation Center) arelocated within 1/4 mile of the school. The Generation Center also uses the sanitary treatment plant. The site is not on the U.S. Environmental Protection Agency's (EPA) National Priorities List (NPL).
MTBE was found in the school's drinking water and in two residential drinking water wells near the school. The concentrations contained in well water at the residences (9.2 and 2.5 micrograms per liter (µg/L), respectively) were not as high as the levels most recently reported in the school's drinking water. As of spring 2003, efforts are continuing to determine the extent of MTBE contamination and to identify other private wells that might be located in the direction of flow of the contaminated groundwater plume and to investigate permanent solutions to provide clean drinking water to affected community members (1).
Well water samples were collected and analyzed by an independent laboratory selected by theschool corporation. Well water samples also were collected and analyzed by IDEM's contractorsfor the school, as well as other locations in the area (e.g., residences, local salvage yard, and localgas station). MTBE was first found in the school's well in March 2000. Concentrations increasedin 2001 and 2002. Table 1 illustrates this.
Exposure stopped in April 2002, when the school was provided with an alternate water supply, andthe affected residences were provided with filters to remove MTBE from the water. Exposure couldoccur again if filters are not adequately maintained or if the school resumes use of the contaminated well water. The filters in the residences are being provided and maintained bythe parties considered responsible for the occurrence of the MTBE contamination.
|Date||MTBE* detected (µg/L)||Drinking Water Advisory Range (µg/L)†|
|3/13/2000||32||20 - 40|
|2/19/2001||160||20 - 40|
|3/21/2002||350||20 - 40|
* Methyl tert - butyl ether.
† U.S. Environmental Protection Agency Drinking Water Advisory recommendation (based on odor and taste).
Children and others at the school were exposed to MTBE in drinking water for about 2 years. Residents living in the two residences found to have MTBE in the well water also were exposed toMTBE-contaminated drinking water. MTBE in the water was ingested, but some of it also wasinhaled, as it evaporates from the water. Inhalation exposure was more likely to have occurred inresidences that had contaminated well water because the residents showered, washed clothes, andperformed other household chores that would have provided more opportunities for MTBE tovolatilize (evaporate). People also came into dermal (skin) contact with MTBE-contaminated waterwhen they washed their hands or showered in the water. Skin contact is not expected to contributeas much to total exposure as ingestion and inhalation because the skin forms somewhat of aprotective barrier.
The Indiana State Department of Health (ISDH) estimated exposure doses on the basis of the worst-case scenario. Although people at the school were exposed for very short durations of time duringthe school day, ISDH based estimated exposures on adults and children living in residencescontaining MTBE at the maximum level found every day of the year. ISDH estimated that an adult,weighing 70 kilograms (about 155 pounds), would drink about 2 liters of water each day, and a child,weighing 10 kilograms (about 22 pounds), would drink about 1 liter of water a day. That scenariois conservative because it overestimates the actual exposure that any one person was likely to havereceived.
Doses were estimated using the following equation:
|IDw||= ingestion exposure dose (milligrams per kilograms of body weight per day- (mg/kg/day)|
|C||= contaminant concentration (milligrams per liter [mg/L])|
|IR||= ingestion rate (liters per day [L/day])|
|EF||= exposure factor (unitless)|
|BW||= body weight (in kilograms [kg])|
Doses were estimated for both children and adults at the highest level (350 micrograms of MTBE per liter (µg/L) of water that was found in the school's drinking water.
The inhalation dose is assumed to be approximately the same amount as the ingestion dose; therefore, the total adult dose is estimated at approximately 0.02 mg/kg/day, and the total estimated child's dose is estimated at approximately 0.06 mg/kg/day. These levels are several orders of magnitude below the doses at which occupationally exposed persons have reported adverse health effects. No information is available about health effects to the general population, and relevant animal data are sparse (2).
However, unpleasant odors and tastes, such as those associated with MTBE in drinking water, cancause people to have physical reactions. Some people might feel sick to their stomach. Others mightdevelop headaches or nose irritation. Parents reported that some children did experience these typesof symptoms. These symptoms were expected to subside once exposure stopped, and most parentswho reported children with these symptoms did believe the children were better after an alternatewater supply was provided. No permanent, non-cancerous adverse health effects are expected as aresult of the exposures (2).
MTBE has not been shown to be associated with cancer in humans; therefore, the exposures are notexpected to result in cancer. In rat studies, doses that were administered at levels 1,000,000 timesor more than the highest doses estimated for people at or near the school resulted in an increase ina type of testicular cancer, lymphoma, and leukemia (2).
The Indiana State Department of Health (ISDH) and the Agency for Toxic Substances and DiseaseRegistry (ATSDR) recognize that there are unique vulnerabilities to be considered for chemicalexposure in children, especially in scenarios when communities are faced with contaminatedenvironmental media (e.g., air, water, soil), in this case drinking water. As part of ATSDR's ChildHealth Initiative, ISDH and ATSDR evaluate whether site-related exposures will be of particularconcern for children.
In general, children appear to be more sensitive to the effects of contaminants because they aresmaller, resulting in higher doses of toxic exposure per body weight. The developing body systemof children can sustain damage if exposures occur during certain growth stages. Additionally,children have a greater body burden of contamination than adults due to their smaller size. However,no evidence exists that suggests MTBE will affect children differently than it does adults.
Through conversations with parents of children attending the school, ISDH learned that somechildren experienced symptoms, such as gastrointestinal distress, while exposed to contaminateddrinking water. Parents did believe that those symptoms subsided once an alternate water supply wasavailable (3). Health education regarding MTBE exposure would be helpful to school administratorsand the nearby community.
The Indiana State Department of Health (ISDH) and the Agency for Toxic Substances and DiseaseRegistry (ATSDR) conclude the following:
- As long as an alternate water supply is used and the residential filters on the water fromcontaminated water wells are maintained, the drinking water at the school and in the nearbyresidences, people are not likely to become ill. Because levels found have not been shown to causeadverse health effects in the occupational setting, but little data are available about exposure to thegeneral population, the contaminated groundwater poses no apparent public health hazard. The watercan be used without fear that unpleasant tastes and odors might cause stomach upsets and othersymptoms often associated with taste and odors. Persons exposed in the past to MTBE at LincolnElementary school and in their nearby residences might have experienced those types of discomforts.The symptoms were expected to stop when exposure stopped in April 2002, when the school wasprovided bottled water for drinking, cooking, and cleaning and water filters were installed on theprivate wells. No permanent adverse health effects are expected as a result of those exposures.
- Investigation to identify the geographical extent of the MTBE plume and other private wells thatmight be impacted should continue to identify possible exposures.
- Health education would help school administrators and nearby residents understand the healthimplications of MTBE exposure.
- Continue to provide Lincoln Elementary School and other affected community residences withclean water until a permanent solution is determined.
- Determine the extent of the plume and whether other private wells that are in the direction ofgroundwater flow are affected to ensure that others persons are not being exposed
- Provide health education support to Lincoln School and the community.
- The Indiana Department of Environment (IDEM) will ensure that the school and otheraffected individuals receive a clean and safe water supply.
- IDEM and/or designated contractors will continue to investigate the extent of the plume.
- ISDH will provide health education support to Lincoln School and the community.
(1) Mundell and Associates, Inc. Initial Site Characterization report to Indiana Department of 2000Environmental Management. Indianapolis: 2000 Dec.
(2) Agency for Toxic Substances and Disease Registry (ATSDR), Toxicological profile for methyltert - butyl ether. Atlanta: U.S. Department of Health and Education; 1996 Aug.
(3) Agency for Toxic Substances and Disease Registry (ATSDR). Public Availability Session atLincoln Elementary School in DeMotte, Indiana: Unpublished data, 2002 U.S. Department of Healthand Human Services; May 2002.
(1) U.S. Environmental Protection Agency (EPA). Drinking Water Advisory: ConsumerAcceptability Advice and Health Effects Analysis on Methyl tert- butyl ether (MTBE). Washington:U.S. Environmental Protection Agency; 1997 Dec.
(2) Agency for Toxic Substances and Disease Registry (ATSDR), ToxFAQs TM for Methyl Tert -Butyl Ether (MTBE). Atlanta: U.S. Department of Health and Human Services; 1997 Sep.
Environmental Epidemiology Section
Indiana State Department of Health
Category A. Urgent Public Health Hazard
Actions must be taken immediately to mitigate and/or prevent exposures or to prevent harm from physical hazards present at the site.
Category B. Public Health Hazard
Exposures can adversely impact public health, but commitments have made to stop the exposure or to eliminate the physical hazards.
Category C. Indeterminate Public Health Hazard
Critical exposure information is insufficient or missing, so no conclusion can be made about the effects to public health.
Category D. No Apparent Public Health Hazard
Exposure may be occurring, but not at levels that would be harmful to humans.
Category E. No Public Health Hazard
Exposures never occurred and never will.
This MTBE Contamination in School Water and Residential Wells Health Consultation wasprepared by the Indiana State Health Department in cooperation with the Agency for ToxicSubstances and Disease Registry. The health consultation is in accordance with guidelines and procedures present at the time the health consultation was begun.
Gail D. Godfrey
Technical Project Officer
DHAC, SSAB, SPS
This health consultation has been reviewed by the Division of Health Assessment and Consultation, ATSDR. ATSDR concurs with the findings in the health consultation.
Chief, SPS, SSAB, DHAC, ATSDR