CHEMICAL COMMODITIES, INCORPORATED
OLATHE, JOHNSON COUNTY, KANSAS
The Chemical Commodities, Inc. (CCI) site, which occupies about 1½ acres, is in alargely residential area of Olathe, Kansas. The facility, in operation from 1951 until1989, stored and recycled chemicals that were surplus, off-specification, or had exceededtheir specified shelf life (1). Chlorinated solvents stored at the facility leaked onto the soiland contaminated the shallow groundwater, forming a plume of contaminants whichmigrated off-site into the adjacent residential neighborhood. Previous soil vapor andcrawl space air sampling indicate a potential for volatile compounds in the soil andgroundwater to migrate to indoor air (1,2,3).
In September and October 2002, Environmental Protection Agency (EPA) collectedindoor air samples in the living area (family room, living room, or bedroom) and crawlspace of eight residences and in the living area and the basement of another house todetermine if chemicals in the groundwater plume are volatilizing into the houses locatednear the CCI site. EPA has requested that the Agency for Toxic Substances and DiseaseRegistry (ATSDR) evaluate results of air samples and address the following issues:
- EPA's response action decision to install ventilation systems and conduct additionalair sampling in the affected area; and
- EPA's conclusions that there are potential cancer and non-cancer risks associated withchronic exposures to the levels of contaminants found in crawl spaces and living spacesof homes near the site (4).
ATSDR has prepared this Health Consultation to address the EPA request.
Available Data and Data Limitations
EPA staff collected indoor air samples in crawl spaces, a basement, and in the livingareas of residences, in September and October 2002, to better characterize the impact ofsoil gases migrating into homes above the CCI groundwater plume. Indoor air sampleswere collected continuously over a 24-hour period from nine homes using a pressurizedmetal cylinder (SUMMA© canister) and analyzed for volatile compounds (4).
Twenty-four hour sampling provides a time weighted average of the concentrations ofchemicals in the indoor air over that period of time. Because only one round of samplingis analyzed for this indoor air evaluation, only a "snapshot" of exposure to contaminationat one point in time is provided. Actual concentrations of contaminants may vary inhomes based on seasonal changes, heating and ventilation system use, and other factors. Additional information on these factors and the possible impacts on the concentrations ofcontaminants present in the air are not provided from one round of sampling.
In further evaluating the quality of the available data, another data concern has been raised. It should also be noted that duplicate samples were collected at two of the homes sampled. At one of the homes, the concentrations of contaminants in the initial sample and duplicate sample varied by three orders of magnitude (0.186 µg/m3 vs. 377 µg/m3). It is possible that this variation may be the result of sampling or laboratory error. Additional quality assurance information was not provided for these samples.
Indoor air exposure pathway
ATSDR identifies human exposure pathways by examining environmental and humancomponents that might lead to contact with a contaminant. A pathway consists of fiveprincipal elements: source of contamination, transport through an environmentalmedium, point of exposure, route of exposure, and an exposed population. Completedexposure pathways are those for which the five elements are evident, and indicate theexposure to contaminants has occurred in the past, is currently occurring, or is expectedto occur under future conditions. As part of this Health Consultation, ATSDR focused onthe evaluation of the available indoor air data and the potential for health effects resultingfrom inhalation of contaminants, also referred to as the indoor air exposure pathway.
It is possible for contaminants to volatilize from soil and groundwater, migrate throughthe air spaces in soil above groundwater, and enter buildings. Volatile chemicals cancollect in the home and be inhaled by dwellers. Many variables can influence the levelsof volatile chemicals in the home from the soil, including contaminant chemicalproperties, soil characteristics, seasonal variations, and building construction.
Air samples from crawl space/basement and indoor living areas were considered in thisevaluation. Exposure to air from crawl space is assumed to be limited to occasional activities, such as home repair or seasonal maintenance. ATSDR does not consider crawlspace air to be full-time breathable air. However, crawl space air data indicates that thepotential may exist for contaminants to impact air within the living spaces of homes. Indoor air samples, collected from living spaces, were considered to address long-termexposures to residents. Short-term exposure to crawl space air was evaluated in thisHealth Consultation. In addition, long-term crawl space data, considered as a worst-casescenario, was also considered for informational purposes.
The first step of ATSDR's evaluation process involved screening the available indoor airdata to determine the contaminants of concern (COCs). As part of the ATSDR screeningprocess, maximum detected concentrations of contaminants were compared withComparison Values (CVs) to determine which chemicals required additional evaluation. CVs are concentrations of chemicals in the environment, below which no adverse healtheffects are expected to occur. CVs are generic, non-site-specific values and can be basedon either carcinogenic (cancer-causing) or non-carcinogenic effects. Non-cancer valuesare calculated from ATSDR's Minimal Risk Levels (MRLs) and/or EPA's ReferenceConcentrations (RfCs). ATSDR MRL's are derived for continuous inhalation exposureover a 24-hour period, for conservatism. Many individuals may go to work or schooland, therefore, have may be exposed to potential contaminants for shorter periods oftime. Some of the available CVs for individual contaminants are based on intermediateexposure (14 to 365 days). Because chronic exposure (greater than 365 days) tocontaminants in indoor air is possible, the scientific literature for these contaminants wasreviewed, even if concentrations did not exceed the available intermediate exposure CVs. Cancer-based comparison values are calculated from the U.S. Environmental ProtectionAgency's (EPA) inhalation risk unit. CVs based on cancerous effects account for alifetime exposure (70 years) with an unacceptable theoretical excess lifetime cancer riskof 1 case per 1 million exposed people (or 1 x 10-6). When a contaminant concentrationexceeds its respective CV, it does not necessarily indicate that health effects are expectedto occur. Rather, it indicates that further evaluation of the particular contaminant and theways in which individuals might be exposed to it are necessary.
Table 1 presents a list of the contaminants detected in indoor air samples and those thatexceed their respective CVs and are identified as COCs.
|Air Contaminant||Highest detection indoor air (µg/m3)||Highest detection crawlspace air (µg/m3)||Non-Cancer Comparison Value (MRL) (µg/m3)||Cancer Comparison Value (CREG) (µg/m3)|
|trans 1,2- Dichloroethene||2.22||18.5||785||n/a|
Bolded values indicate an exceedance of the non-cancer and/or cancer Comparison Value.
CREG = Cancer Risk Evaluation Guide
MRL = Minimal Risk Level
µg/m3 = micrograms per cubic meter
n/a= not available
Based on the available data, air samples collected from crawl spaces were found tocontain greater concentrations of contaminants that those collected from living spaceareas. Additionally, the majority of the identified COCs were selected as a result ofexceeding their respective cancer CVs. Further evaluation of the identified COCs isdiscussed in the following non-cancer and cancer sections.
When maximum detected concentrations of contaminants exceed non-cancer CVs,additional evaluation of the potential health effects from exposure is necessary. In thesecases, contaminant concentrations measured in indoor air (crawl space and living areas)were then compared to the concentrations from individual studies documented in thescientific literature that have reported non-cancer health effects. Toxicological profiles,prepared by ATSDR for various chemicals, were the primary source of the scientificliterature that is utilized in this part of the evaluation process. ATSDR also utilizedinformation provided in EPA's Trichloroethylene Health Risk Assessment: Synthesis andCharacterization (5).
Based on the results of the CV screening, the only contaminant detected above its non-cancer CV is cis 1,2-dichloroethene (1,2-DCE). Concentrations of cis 1,2-DCE weredetected above the CV in indoor air sample collected from the crawl space in one home. Additional crawl space samples collected from this home, including a duplicate sample,indicated concentrations of 1,2-DCE that do not exceed the non-cancer CV. Review ofthe available scientific literature indicates that health effects are observed atconcentrations that are thousands of times higher than the concentration of 1,2-DCEmeasured in crawl space air. Therefore, health effects are not expected to result fromexposure.
As previously discussed, CVs may only be available for intermediate exposure tocontaminants (14 to 365 days). Because chronic exposure to contaminants (greater than365 days) in air is possible, the scientific literature for these contaminants was reviewed,even if concentrations did not exceed the available intermediate exposure CVs. Thesecontaminants include carbon tetrachloride, 1,1-dichloroethene, trans 1,2-dichloroethene,1,1,2,2-perchloroethane, 1,1,1-trichloroethane, trichloroethylene (TCE), and vinylchloride. The available data for these contaminants indicates that non-cancer healtheffects are not likely to result from exposure, with the exception of TCE. Therefore, amore detailed review of the scientific literature for TCE was conducted.
A review of the available human and animal studies of inhalation to TCE indicates central nervous system, endocrine, and liver effects among individuals exposed to TCE via inhalation (5,6). Concentrations of TCE detected in indoor air samples collected in living spaces and crawl spaces exceed the provisional EPA of 40 µg/m3. Adverse health effects, particularly central nervous system effects, have been reported in several occupational and laboratory exposure studies at concentrations within two orders of magnitude of those measured in indoor air in livings areas and crawl spaces associated with the CCI site. Based on the evaluation of scientific literature and TCE concentrations in indoor air associated with the CCI site, ATSDR concludes that non-cancer health effects, particularly to the central nervous system, may occur among individuals with long-term exposure to TCE in indoor air (crawl spaces and living areas) associated with the CCI site. Short-term exposure to crawl space air is not likely to be associated with health effects.
Exposure to a cancer-causing compound, even at low concentrations, is assumed to beassociated with some increased risk for evaluation purposes. The estimated excess riskof developing cancer from exposure to contaminants associated with the site wascalculated with consideration of site-specific factors, such as contaminant concentration,inhalation rate (20 m3/day), exposure duration (365 days/year), exposure frequency (30years), and body weight (70 kilograms). ATSDR also incorporated EPA's chemical-specific Cancer Slope Factors (CSFs or cancer potency estimates) to calculate theincreased excess lifetime cancer risk. This calculation is not a specific estimate ofexpected cancers. Rather, it is an estimate of the increase in the probability that a personmay develop cancer sometime during his or her lifetime following exposure to aparticular contaminant. Therefore, exposure is averaged over the lifetime of anindividual (365 days/year for 70 years). There are varying suggestions among thescientific community regarding an acceptable excess lifetime cancer risk, due to theuncertainties regarding the mechanism of cancer. The recommendations of manyscientists and EPA have been in the risk range of 1 in 1,000,000 to 1 in 10,000 (asreferred to as 1 x 10-6 to 1 x 10-4) excess cancer cases. An increased lifetime cancer riskof 1 in 1,000,000 (or 1 x 10-6) or less is generally considered an insignificant increase incancer risk.
Risk calculations indicate that an elevated cancer risk is associated with exposure tocontaminants associated with the CCI site that are present in indoor air, primarily due tothe presence of TCE. Although a cancer CV is currently not available for TCE, there isscientific literature that indicates the potential for cancerous effects associated with TCEexposure. Therefore, the available cancer studies of humans and animals wereconsidered in the evaluation of TCE (5). Elevated cancer risk has been observed forthose exposed to indoor air in living areas (4 x 10-3). Cancer risk was not evaluated forshort-term exposure to crawl space air since it is considered to be very limited in durationand frequency. Long-term exposure to crawl space air is expected to be associated withan elevated cancer risk (2 x 10-2). A review of the scientific literature indicates inhalationexposure to TCE has been associated with various types of cancer, including liver,kidney, and non-Hodgkin's lymphoma (5,6).
ATSDR reviewed the available indoor air data for the CCI site and concludes thefollowing:
- Based on the limited available indoor air data, inhalation of contaminants(primarily TCE) in living spaces of homes overlying the CCI site may pose apublic health hazard. It is possible for exposure to be associated with cancer andnon-cancer health effects. ATSDR's conclusion is consistent with EPA'sconclusion for the evaluation of indoor air from living spaces of homes in thevicinity of the CCI site.
- Contamination detected in crawl space air is not likely to pose a health hazardbecause exposure in these areas is expected to be limited in duration andfrequency (i.e., maintenance, etc.). However, the presence of contaminants incrawl space air indicates the potential for higher levels of contaminants to enterthe home, which may result in long-term exposure to residents. Long-termexposure to contaminant concentrations measured in crawl space is likely to beassociated with cancer and non-cancer health effects. Additional air sampling isneeded for further evaluation of the likelihood of this occurrence.
- Limited data was available for the evaluation of inhalation exposure tocontaminants associated with the CCI site. Therefore, it is recommended thatadditional monitoring of the indoor air is necessary to determine if higher levelsof contamination from crawl space enter air in living spaces of the home due toseasonal changes, heating and ventilation system changes, and other factors.
- In the event that additional data confirms the presence of indoor air contaminantsat concentrations observed in samples collected in September and October 2002,it is recommended that activities be undertaken to reduce exposure to residents. These activities may include the installation of ventilation systems to minimizeexposure of residents to contaminants present in indoor air, as proposed by EPA.
Annmarie DePasquale, M.P.H.
Division of Health Assessment and Consultation
Superfund Assessment Branch
LTJG Shawn Blackshear, M.S.
Health Service Officer, USPHS
Office of Regional Operations, Region 7
- Groundwater Technology, Inc. Site Characterization Report Former ChemicalCommodities, Inc. 1996.
- Agency for Toxic Substances and Disease Registry. U.S. Public Health Service. Health Consultation: Chemical Commodities Inc. April 30, 1996.
- U.S. Environmental Protection Agency. Memorandum. Request for Technical Assistance onChemical Commodities, Inc. Site. From Mary Peterson, USEPA Region 7, Superfund Division, RemedialProject Manager to Shawn Blackshear, ATSDR Region 7, Office of Regional Operations, RegionalRepresentative; January 22, 2003.
- U.S. Environmental Protection Agency. Final Report for Toxic Air Monitoring in Residences NearChemical Commodities, Inc. Region VII Environmental Services Division, U.S. Environmental ProtectionAgency; November 13, 1989.
- U.S. Environmental Protection Agency. Trichloroethylene Health Risk Assessment: Synthesis andCharacterization. USEPA Office of Research and Development. August 2001.
- Agency for Toxic Substances and Disease Registry. U.S. Public Health Service. Toxicological Profile for Trichloroethylene. September 1997.