Ethylene Dichloride (EDC) and Other Contaminants
Found in a Residential Well Water Sample
LAKE CHARLES, CALCASIEU PARISH, LOUISIANA
The Louisiana Department of Environmental Quality (LDEQ) requested assistance from theLouisiana Department of Health and Hospitals, Office of Public Health (LOPH), Section ofEnvironmental Epidemiology and Toxicology (SEET) regarding the discovery of ethylenedichloride (EDC) or 1,2-dichloroethane in a residential well near Lake Charles, Louisiana(Attachments 1 and 2). The private wells at residential properties, and commercial properties inthe vicinity, have been sampled for volatile organic compounds (VOCs) biannually since 1993 asthe result of two known EDC plumes within the 200-foot sands of the Chicot Aquifer and thediscovery of EDC in other nearby commercial wells supplied from the same aquifer. The City ofLake Charles draws its municipal drinking water from the 700-foot sands.
The home with the well is located in a highly industrialized area. The Louisiana Toxic ReleaseInventory Report, an annual LDEQ report of discharges by manufacturing facilities in the state,notes that 20 manufacturing facilities are in Calcasieu Parish . Calcasieu Parish ranks 6thamong the parishes in discharges to air(1) and 5th in discharges to surface water.
In 1992, the presence of EDC was confirmed in the two water supply wells at the ChateauCharles Hotel. Both wells were completed in the 200-foot sands of the Chicot Aquifer. Thewells were sampled about seven times that year, and EDC ranged in concentration from 7micrograms per liter (µg/L) to 55 µg/L . In 1993, the hotel was connected to the local publicwater supply.
In a 1997 letter, the LDEQ and Department of Transportation and Development (DOTD) agreedthat the hotel could maintain the two wells for fire protection with the stipulation that the wellsbe properly maintained and accessible to the LDEQ for sampling purposes. The wells have beensampled occasionally since 1993, and the results have shown no detectable levels of EDC.
The hotel is located south of CONDEA Vista, and north of PPG Industries, Inc. Both facilitiesproduce EDC, and both have areas of EDC-contaminated groundwater. Union Pacific Railroadlines are located just north and south of the hotel, and these tracks are used to transportchemicals. Groundwater flow is generally to the south.
Several private wells completed in the 200-foot Chicot Aquifer are in the area around the hotel. LDEQ conducted a well survey of the area, using DOTD data and performing a door-to-doorsearch. That well survey identifies all the water wells within a half-mile radius of the hotel. Mostof these wells supply bathrooms and kitchens, and as a result the volume of water pumped is low.
There was only one well identified that provides water for human consumption at a residentialproperty. At all other locations bottled water is supplied for drinking.
In March 1999,EDC was detected in the residential well at 1.6 µg/L. The well was resampled inJune 1999, and EDC was confirmed at 5 µg/L. The residential well water sample was alsoanalyzed for other VOCs including acetone, chloroethane, and 2-butanone (methyl ethyl ketone) (Table 1).
According to LDEQ, the home owner had been informed of his well sampling results as ofSeptember 1999. LDEQ also reported to SEET that no one is currently living in the home.
SEET responded to LDEQ request by letter (Attachments 2 and 3). The response provides thatdecisions regarding future sampling be determined through a meeting between LDEQ,LOPH/SEET, and LOPH Safe Drinking Water.
The contaminants found in the private well water included EDC, 2-butanone, acetone, andchloroethane (Table 1). All are volatile organic compounds. SEET was not provided with asummary of the data validation package so even the data that was presented with a "J flag" wasincluded. A "J flag" indicates that the result is an estimate. A "U flag" indicates that thecompound was present at a concentration less than the detection limit. Acetone (6 µg/L), UJflagged) was also present in the Trip Blank (5 µg/L, UJ qualified). Because acetone was in boththe field sample and the blank, it is likely that it was a laboratory contaminant and was notaddressed further. Chloroethane and 2-butanone are not regulated by the Safe Drinking WaterAct but were compared to other available health based guidance values.
The United States Environmental Protection Agency (USEPA) Region 3 and Region 6comparison values shown in Table 1 include the inhalation exposure pathway resulting fromvolatilization of contaminants from the tap water to the air during showering, dishwashing orlaundering. They do not include dermal exposure to the contaminants during bathing. TheUSEPA maximum contaminant level (MCL) for drinking water and ATSDR comparison valuesdo not take into account inhalation nor dermal exposure to the contaminants during tap water use. Inclusion of these additional pathways of exposure in any calculations would increase the dose of volatile contaminants to which a resident is exposed.
|Concentration in well |
June 2, 1999 (µg/L)*
|USEPA Maximum Contaminant Level (µg/L)||5||5.0||not available||not available|
|ATSDR Drinking Water Comparison Values (µg/L)||7||0.4||6,000||not available|
|USEPA Region 6 Screening Levels (µg/L)||6||0.12||1,900||8,600|
|USEPA Region 3 Risk Based Concentrations (µg/L)||8||0.12||1,900||3.6|
|LDEQ Risk Evaluation/ Corrective Action Program GW_SS (µg/L)†||9||5.0||190||860|
|* µg/L = micrograms per liter . |
† GW_SS = Groundwater Screening Standard.
EDC is an chemical used in the manufacture of vinyl chloride. Previously it was used to clean materials and as a de-greaser. EDC is classified as a B2 carcinogen, a probable human carcinogen. In animal studies, EDC in drinking water resulted in statistically significant increases in a variety of types of cancer in organs, such as the liver, pancreas, and adrenal gland . A single human epidemiologic study identified an increase in colon and rectal cancers in men who consumed water contaminated with EDC . Exposure to other chemicals during these men's lifetimes is likely to have contributed to the cancer but could not be singled out from the exposure to EDC in drinking water.
Noncancerous, adverse health effects from EDC have also been noted in animal studies, but at exposure concentrations far greater than these found in the well water. These effects were seen in the hepatic, renal, and reproductive organs.
The maximum EDC level detected in the private well water sample was 5 µg/L, which is also USEPA's MCL. This level exceeds the USEPA Region 6, and Region 3 screening levels and ATSDR comparison values which range from 0.12 µg/L to 0.4 µg/L. Although health effects would be unlikely at this level, LOPH recommends future sampling of this well to ensure that the levels of EDC do not increase to a level that may represent a health concern.
The level of 2-butanone in the well water, 27 µg/L, is far below all four of the screening values presented in Table 1, which range from 190 µg/L to 6,000 µg/L. Therefore 2-butanone is not considered to be a health concern.
The No Observed Adverse Effect Level (NOAEL), which forms the basis of the USEPA Reference Dose (RfD) for 2 -butanone, is derived from the finding of decreased fetal birth weight of rat pups born from parents exposed to 2-butanone via drinking water . The intermediate metabolite of 2-butanone, 2- butanol, was mixed into the drinking water of infant rats. A decrease in birth weight was noted in the off-spring of these rats. The NOAEL of 1,771 milligrams per kilograms per day (mg/kg/day) was noted for a 1 percent solution of 2-butanol in drinking water. The Lowest Observed Adverse Effect Level (LOAEL) of 3,122 mg/kg/day was set at 3 percent of 2-butanol in drinking water. The level of 2- butanone in the private well water is vastly lower at about one ten thousandth of a percent.
The concentration of chloroethane in the well water is 0.6 µg/L. This value is less than the three comparison values found ranging from 3.6 µg/L to 8,600 µg/L, and is therefore also at a level which is not a health concern.
Children are uniquely susceptible to adverse effects through exposure to chemicals. Both before birth and as young children, organs form that are necessary for survival and maintenance throughout their lives. These organs can be more susceptible to damage during immaturity. Also, malformations that might occur during development can result in irreversible impairment.
Drinking water is an exposure route of particular concern to infants. In the first six months of life, babies drink seven times as much water per pound of body weight as do adults in the United States. This health consult has used conservative comparison and screening values to consider children. Furthermore, the presence of 2-butanone in the water, was of concern because the NOAEL on which the USEPA's RfD is based is the decreased fetal birth weight of rat pups born to parents exposed via drinking water .
The quality of the water for ingestion in the residential well is considered to presently be No Apparent Public Health Hazard [5, 6, 7, 8]. The EDC concentration is just at the USEPA MCL but above the USEPA Region 6 and Region 3 comparison values. The other contaminants identified, chloroethane and 2-butanone are not contaminants regulated by the Safe Drinking Water Act. However, the concentrations of these contaminants are well below any levels that would initiate further action according to ATSDR or Regional EPA branches. They are presently not a public health concern.
- The state agencies should continue to sample the residential well used for potable purposes and identify any future residential wells that may be installed in the area because of known groundwater contamination.
- An inter-agency consensus should be reached regarding the frequency of future sampling.
- An assessment should be made of the indoor air concentrations of contaminants in the other residences if future sampling results begin to approach levels at which volatilization from use of the water in the home could become a health concern.
- The residential property owner of the private well that was sampled should be regularly updated on the findings of the state agencies.
- Louisiana Department of Environmental Quality (LDEQ). Toxic Release Inventory. BatonRouge, Louisiana. 1999.
- Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for 1,2 Dichloroethane (Ethylene Dichloride). Atlanta: US Department of Health and HumanServices. 1994.
- National Cancer Institute (NCI). Bioassay of technical grade 1,2 dichloroethane (ethylene dichloride) for possible carcinogenicity. Bethesda, MD: NCI, Division of Cancer Cause and Prevention. 1978.
- US Environmental Protection Agency (USEPA). Integrated Risk Information System (IRIS). Methyl ethyl ketone (2-butanone). Cincinnati: USEPA, Office of Health and Environmental Assessment, Environmental Criteria and Assessment Office. 1999.
- USEPA. National Primary Drinking Water Regulations. Office of Ground Water andDrinking Water. 1999.
- USEPA. Human Health Medium Specific Screening Levels. Web site address www.epa.gov/earthlr6/6pd/rcra_c/pd_n/r6lines.pdf. Region 6, USEPA. 1999.
- ATSDR. Drinking Water Comparison Values. Atlanta: US Department of Health and HumanServices. May 10, 1999.
- USEPA Risk Based Concentrations. Web site address www.epa.gov/reg3hwmd/risk/rbc.pdf. Region 3, USEPA. 1999.
- LDEQ. Risk Evaluation/Corrective Action Program (RECAP). Baton Rouge, LA: LDEQ.December 20, 1998.
Louisiana Office of Public Health
ATSDR Regional Representative
ATSDR Technical Project Officer
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
This Health Consultation, Ethylene Dichloride and Other Contaminants Found in a Residential Well Water Sample (Lake Charles, Louisiana), was prepared by the Louisiana Office of Public Health under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the health consultation was begun.
Tammie McRae, MS
Technical Project Officer, SPS, SSAB, DHAC
The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health consultation and concurs with the findings.
Chief, State Program Selection, DHAC, ATSDR
1. Sixth of parishes with facilities that released more than 100,000 pounds to the air.