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PUBLIC HEALTH ASSESSMENT

NORTH RAILROAD AVENUE PLUME
ESPAÑOLA, RIO ARRIBA COUNTY, NEW MEXICO


SUMMARY

The Agency for Toxic Substances and Disease Registry (ATSDR) has evaluated the public health significance of groundwater contamination that underlies parts of the City of Española, New Mexico and the adjacent Santa Clara Pueblo, defined as the North Railroad Avenue Plume (NRAP) site. The U.S. Environmental Protection Agency (EPA) has added the NRAP site to its National Priorities List (NPL) and, therefore, ATSDR is mandated by Congress to prepare a public health assessment (PHA) for the site.

ATSDR prepared the initial release of this PHA, dated September 1999, using data available through March 1999. The initial release focused solely on contaminated groundwater and potential exposures to individuals within the City of Española boundary. This public comment release of the PHA evaluates contamination and potential exposure to individuals within the City of Española, as well as on the adjacent Santa Clara Pueblo. This public comment version of the PHA comprehensively re-evaluates the data included in the initial release and evaluates the extensive newer data obtained during recent field investigations at the site. The public comment release of the PHA is a comprehensive, stand-alone document and fully replaces the initial release of the PHA prepared for the site.

Tetrachlorethylene (PCE), trichloroethylene (TCE), which is a PCE breakdown product, and a few other chlorinated chemicals were first discovered in 1989 during sampling initiated for two municipal supply wells (Bond and Jemez wells). This discovery occurred the first time that analyses of city well water for volatile organic compounds (VOCs), a class of compounds that includes PCE, TCE, and other chlorinated chemicals, was required under EPA's Safe Drinking Water Act (SDWA). The city discontinued use of the Bond and Jemez wells when the 1989 sampling results became available. Investigations in the area indicated that the Norge Town Dry Cleaner and Laundromat (Norge Town) facility at 162 North Railroad Avenue (currently 113 North Railroad Avenue) is the likely source of the chlorinated chemicals in the groundwater.

Exposure pathways of principal interest discussed in this PHA address water supplied by the former public wells (Bond and Jemez wells), groundwater from private non-drinking water wells (used for irrigation and other uses), indoor air, outdoor air, and soil. Potential exposure via surface water and sediment from the Rio Grande and adjacent ditches has also been evaluated in this document.

Based on evaluations of the available data and associated exposure pathways, ATSDR concludes the following:

  • Past exposure to groundwater from the public water supply (Bond and Jemez wells) posed a public health hazard to individuals residing within the City of Española. It should be noted that use of the contaminated public water supply wells was discontinued in 1989, when the contamination was discovered.
  • Individuals residing on the Santa Clara Pueblo did not receive their drinking water from the public water supply within the City of Española in the past. Therefore, these individuals were not exposed to contaminants from the Bond and Jemez wells. Individuals residing on the Santa Clara Pueblo received their water from private wells and Pueblo community supply wells. No contaminants have been detected in private wells used for drinking water purposes, which are located directly adjacent to Santa Clara Pueblo Trust Land. The Pueblo community supply well has also not been impacted by contamination. Based on the available information, no health effects are expected among individuals from the Santa Clara Pueblo who use private wells and/or community supply wells for drinking water purposes. Therefore, no apparent public health hazard is posed from exposure.
  • Exposure to groundwater from private non-drinking water wells (within the City of Española), soil, indoor and outdoor air, sediment, and surface water indicate no apparent public health hazard.
  • ATSDR has evaluated community health concerns and concluded that no adverse health effects are expected to occur based on the issues raised.
  • Information reviewed by ATSDR indicates that repairs have been made to the Norge Town facility to effectively prohibit future contaminant releases to groundwater. In addition, proposed remediation efforts at the site are considered adequately protective of public health.

Based on the conclusions of the PHA, ATSDR has made the following recommendations:

  • It is recommended that no new private wells be installed in the vicinity of the site.
  • Twelve private drinking water wells, located directly adjacent to Santa Clara Pueblo Trust Lands, should be periodically monitored by NMED until cleanup measures are completed to determine whether these wells remain unimpacted from local groundwater contamination.
  • Active private wells within the City of Española that are used for non-drinking water purposes should be monitored periodically by NMED until cleanup measures are completed to determine whether the levels of contaminants (if present) are of public health significance.
  • Limited surface water and sediment sampling should be conducted periodically by NMED until cleanup measures are completed to determine whether surface water and sediment remain unimpacted by contamination.

INTRODUCTION

The Agency for Toxic Substances and Disease Registry (ATSDR), in Atlanta, Georgia, is one of the agencies of the U.S. Department of Health and Human Services. ATSDR is required to conduct a public health assessment (PHA) for sites proposed for the Environmental Protection Agency's (EPA's) National Priorities List (NPL), under authorities provided by the Superfund law (Comprehensive Environmental Response, Compensation, and Liability Act of 1980 or CERCLA) and its amendments. In July 1998, EPA proposed the North Railroad Avenue Plume (NRAP) site in the City of Española, New Mexico for the NPL and the site was formally listed in January 1999.

ATSDR researches and prepares written PHAs to evaluate a community's exposure to contaminants at hazardous waste sites. ATSDR also makes recommendations regarding the public health activities that may be necessary. The evaluation may include some or all of the following broad categories of public health activities:

  • assessing how people might be exposed to contaminants;
  • evaluating possible health effects from exposure to contaminants for a variety of appropriate public health actions;
  • recommending medical tests, health education, and health promotion;
  • making recommendations to local, state, and federal agencies; and
  • involving and working effectively with the community.

In the initial release of the PHA, ATSDR evaluated the public health significance of groundwater contamination that underlies the City of Española, New Mexico based on the data available at that time [1]. This public comment version of the PHA includes a comprehensive evaluation of the data previously collected and the additional sample data collected through 1999 [2]. The public comment version of the PHA also evaluates potential exposure to individuals on the adjacent Santa Clara Pueblo, which was not addressed in the initial document. ATSDR reviewed available environmental data, exposure pathway information, toxicological information, and community health concerns from individuals within the City of Española and on the Santa Clara Pueblo to determine whether adverse health effects were/are likely to occur among exposed individuals. Evaluations also considered whether actions are needed to reduce or prevent the potential for significant site-related exposure and associated adverse health effects. This public comment version of the PHA is a comprehensive, stand-alone document and fully replaces the initial release.

The NRAP site is comprised of zones of groundwater contaminated with chlorinated compounds, such as PCE (also referred to as perchloroethylene or tetrachloroethylene) and trichloroethylene (TCE), a breakdown product of PCE. These contaminants also belong to a class of compounds referred to as volatile organic compounds (VOCs). Multiple groundwater contamination zones or plumes (also referred to as columns of water containing chemicals) lie beneath part of southwestern Española. The shallow contaminant, dissolved-phase groundwater plume is hydraulically connected with the Rio Grande and extends to within 10 feet of the Rio Grande. However, contamination has not been detected in the river. The source of groundwater contamination with PCE and other associated chemical compounds at the site appears to have originated at the Norge Town Dry Cleaner and Laundromat (Norge Town) [2].

As part of the initial release of the PHA, potential exposures to a separate contamination plume in the plaza area within the City of Española were also included in the evaluation. This separate groundwater contamination plume consists of fuel-related contaminants (benzene, ethylbenzene, toluene, and xylenes, which are also referred to as BTEX contaminants) associated with leaking underground storage tanks at nearby former service stations located southwest of the Norge Town facility (near Hill Street and Los Alamos Avenue) [2]. Although the petroleum-impacted groundwater is not part of the NRAP site, it was addressed in the initial PHA because the BTEX plume is located in the vicinity of the PCE plume. Because the BTEX contamination has separate contaminant source(s) and on-going investigation at the site is being conducted under the authority of the New Mexico Environment Department (NMED), the BTEX contamination will not be evaluated further in this updated PHA. The information presented in the initial release of the PHA has been provided in Appendix A for the reader's information. Appendix A also includes contact information for a state representative who can provide additional information on the status of the BTEX contamination site investigation.


SITE BACKGROUND

Site Location

The NRAP site consists of an approximately 58-acre plume of contaminated groundwater extending in an elliptical shape to approximately 3/4 miles south, southeast of the source at the Norge Town facility, which is located at 113 North Railroad Avenue (previously 162 North Railroad Avenue) in Española, Rio Arriba County, New Mexico.

Site History

The building at the Norge Town facility was built between 1960 and 1965, according to aerial photographs. It is estimated that PCE has been used in the dry cleaning process at Norge Town from approximately 1970 to present. The original coin-operated dry cleaning machines were replaced with new, closed system machines in the late 1980s and currently remain at the Norge Town facility. Approximately 150 gallons of PCE are currently used each year at the facility. According to the current property operator, some of the PCE is recycled, while unusable sludge Exiting ATSDR Website is stored in small barrels until disposed of by a contracted company.

Previous investigations showed high levels of chlorinated chemicals in materials contained in the facility lint trap. The lint trap is located 13 inches east of the Norge Town facility building and approximately 20 feet south of the northeastern corner of the building. The purpose of the lint trap was to remove particles and lint from the Norge Town facility effluent prior to discharge to the sewer system. The piping associated with the lint trap was in disrepair and some contaminants in the effluent were released to the environment rather than discharged to the sewer system. The piping has since been removed and the lint trap has been filled with sand and can no longer be used [2].

PCE and some other chlorinated chemicals were discovered in sampling initiated in 1989 for two public supply wells (Bond and Jemez wells). This was the first analysis of city water for VOCs required under EPA's Safe Drinking Water Act (SDWA). ATSDR's discussions with City of Española utility personnel indicate that use of the Bond and Jemez wells was discontinued based on the 1989 sampling results [2].

The available analytical data indicates that soil and groundwater at the NRAP site have been contaminated with chlorinated solvents, including PCE and TCE. Groundwater in the vicinity of the site has been measured at a depth of 5 feet below the surface of the ground. The PCE contamination exists in three groundwater units: the shallow unit (also referred to as an aquifer) (about 5 to 130 feet deep), the upper deep unit (about 130 to 210 feet deep), and the lower deep unit (greater than 210 feet deep). Although PCE and related compounds have been detected in each of these groundwater units, the shallow unit is the most heavily contaminated. The PCE contamination extends from the Norge Town facility and spreads to the southeast due to the natural flow direction of the shallow groundwater in the area. Contamination extends from the Norge Town facility to the Santa Clara Pueblo, across the Santa Clara Ditch and towards the Rio Grande located to the east of the site. PCE and TCE have been detected in deeper groundwater in the vicinity west of the Jemez well. Currently, contamination in the deeper groundwater extends to State Road 201 and is less extensive than contamination present in shallower groundwater [2]. Contamination of the lower deep aquifer is not yet fully characterized. A vicinity map that depicts the approximate locations of the shallow and deeper PCE groundwater plumes is presented in Appendix B, Figure 1.

Demographics

The population of the City of Española is approximately 11,200. The Santa Clara Pueblo has an estimated population of 2,400 [3]. Appendix B, Figure 2 presents a map and demographic information on the community surrounding the NRAP site. Using 2000 census data, ATSDR has calculated population information for the area within a 1-mile radius of the plumes using an area-proportion spacial analyses technique. These analyses provide the following estimated demographic statistics:

Total population 4,363
White 2,965
Black 21
American Indian, Eskimo, Aleut 329
Asian or Pacific Islander 2
Other Race 893
Hispanic origin 3,614
Children ages 6 and Younger 467
Adults ages 65 and Older 573
Females ages 15 - 44 908
Total housing units 1,831

Land Use and Natural Resources

The NRAP site is located in an area comprised of residential, commercial, and light industrial property. Surrounding the Norge Town facility are several unpaved and unvegetated lots that are unfenced and accessible to the public. The shallow PCE plume underlies many businesses, service facilities, some residences, and undeveloped properties within the City of Española. A small portion of the PCE plume has also migrated to the adjacent Santa Clara Pueblo land in the vicinity of the Rio Grande.

Approximately 25 residences within the City of Española overlie the current area of the shallow PCE plume. Many residences in the vicinity of the groundwater plume have private wells that are utilized for irrigation purposes. A single, private drinking water well exists at a residence that overlies the PCE plume within the City of Española. According to the property owners, the well is not in use at this time. Private drinking water wells located on the Santa Clara Pueblo are not overlying the PCE plume. Based on the available data and planned remediation efforts at the site, these wells are not likely to be impacted by contaminants associated with the PCE plume. According to the available records and interviews with residents, wells within 1,000 feet of the Bond and Jemez wells and the vicinity of the PCE plume are not being used for drinking water purposes [2].

Nearly 80% of the residents of the City of Española, or about 8,800 individuals, obtain their drinking water from the municipal water supply. The City of Española has confirmed that all residences within the plume boundary receive drinking water from the city's public water supply based on a building-by-building tour with representatives from the public works department, ATSDR, and New Mexico Environment Department (NMED). Individuals residing on the Santa Clara Pueblo received their water from private wells and Pueblo community supply wells.

The nearest residence to the PCE plume source is about 200 feet east of the Norge Town facility. Las Cumbres Learning Services, Inc., which provides several services to the community including a learning center for disabled children and a daycare center, is located on Hunter Street near the eastern boundary of the shallow PCE plume. The daycare center has a preschool for children of approximately 2 to 5 years of age. In addition, a junior high school, with an enrollment of 1,107 students, is located 1 block east of the Norge Town facility. While Las Cumbres Learning Services, Inc. overlies the shallow PCE plume, the junior high school is not within the plume boundary [2]. Appendix B, Figure 1 presents the location of each of these facilities and the approximate boundaries of the shallow and deeper PCE groundwater plume.

The Rio Grande, which flows north-to-south, is located approximately ½-mile to the east of the Norge Town facility. Individuals residing within the City of Española and the Santa Clara Pueblo use the river for irrigation, raising livestock, fishing, and other recreational purposes. It should be noted that no drinking water intakes from the Rio Grande are located less than 15 miles downstream of the site [3]. The Santa Clara Ditch lies west of the river and conveys irrigation water from the river southward onto the Santa Clara Pueblo.


DISCUSSION

Available Data Used

Several investigations have been conducted from 1989 to 1999 to characterize the extent of the contamination associated with releases to environmental media (for example: soil, groundwater, air, surface water, or sediment) from the site. Available data include groundwater samples collected from the shallow, upper deep, and lower deep groundwater units in the vicinity of the PCE plume. Soil samples (1 to 5 feet deep) were collected at the Norge Town facility, the nearby Las Cumbres Learning Services, Inc., and on the Santa Clara Pueblo. Surface water and sediments from nearby ditches and the Rio Grande were also collected and analyzed for contaminants. In addition, indoor and outdoor air samples were collected in the vicinity of the plume during recent field investigations [2].

Evaluation Process

The process by which ATSDR evaluates the possible health impact of contaminants is summarized in the following section and described in more detail in Appendix C. There are two steps in the evaluation process. The first step involves screening the available data to determine the contaminants of concern (COCs) for each media. As part of the ATSDR screening process, maximum detected concentrations of contaminants are compared with Comparison Values (CVs) to determine which chemicals, if any, require additional evaluation. CVs are concentrations of chemicals in the environment, below which no adverse health effects are expected to occur. In the event that a contaminant concentration exceeds its respective CV, it does not necessarily indicate that health effects are expected to occur. Rather, it is indicated that further evaluation of the particular contaminant and the ways in which individuals might be exposed to it is necessary. It should also be noted that other contaminants may be evaluated further if concerns are received from the community regarding the presence of the particular contaminant(s) [4].

During the second step of the evaluation process, several important factors are considered in order to determine whether chemicals and exposure situations could be a public health hazard. These factors include the sampling locations and data quality, specific exposure route (ingestion, inhalation, or direct skin contact), contaminant concentration, exposure frequency, exposure duration, toxicity information, human susceptibility, and community health concerns. Therefore, the second step involves the calculation of child and adult exposure doses for the identified COCs, which incorporate site-specific (if available) information on these important factors. Exposure doses are estimated amounts of a contaminant that individuals come in contact with as a result of specific exposure situations.

The calculated, site-specific exposure doses are then compared with safe doses (also referred to as health guidelines), which indicate levels below which health effects are unlikely to occur due to exposure. The health guidelines are health-protective values that have incorporated various safety factors to account for varying human susceptibility and the use of animal data to evaluate human exposure. In the event that the calculated, site-specific exposure dose for a chemical is greater than the established health guideline, it is then compared to the exposure doses from individual studies documented in the scientific literature that have reported health effects. Toxicological profiles, prepared by ATSDR for various chemicals, are the primary source of the scientific literature that is utilized in this part of the evaluation process. If a COC has been determined to be cancer-causing (carcinogenic), a cancer risk is also estimated.

A complete discussion of ATSDR's evaluation process is presented in Appendix C.

Pathway Analysis

ATSDR identifies human exposure pathways by examining environmental and human components that might lead to contact with COCs. A pathway analysis considers five principal elements: a source of contamination, transport through an environmental medium, a point of exposure, a route of human exposure, and an exposed population. Completed exposure pathways are those for which the five elements are evident, and indicate that exposure to a contaminant has occurred in the past, is currently occurring, or will occur in the future. ATSDR regards people who come in contact with contamination as exposed. For example, people who reside in an area with contaminants in air, or who drink water known to be contaminated, or who work or play in contaminated soil are considered to be exposed to contamination. Potential exposure pathways are those for which exposure seems possible, but one or more of the elements is not clearly defined. Potential pathways indicate that exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future. However, key information regarding a potential pathway may not be available. It should be noted that the identification of an exposure pathway does not imply that health effects will occur. Exposures may, or may not be, substantive. Thus, even if exposure has occurred, human health effects may not necessarily result.

ATSDR reviewed site history, information on site activities, and the available sampling data. Based on this review, ATSDR identified numerous exposure pathways that warranted consideration. Each of the completed and potential exposure pathways identified for the NRAP site are discussed in the following sections. Additional pathways were also considered in this evaluation. However, these pathways were eliminated for further evaluation based on the available data. The considered and eliminated exposure pathways are also discussed in the following sections. Each of the pathways identified at the NRAP site are summarized in Appendix C, Table 1.

The COCs identified for each of the exposure pathways identified for the NRAP site are discussed in the following sections and presented in Tables 1, 2, 3, and 4. Other contaminants reviewed, but not selected for additional evaluation, are not addressed further in this assessment. For the reader's information, the tables also include the chemical-specific CVs, which ATSDR considered in the selection process. A more detailed discussion of each of the available CVs is presented in Appendix C.

Completed Exposure Pathways

Former Public Water Supply Wells

Groundwater samples were collected from public supply wells from 1989 to 1999 to determine the extent of the PCE groundwater contamination. Public water supply sampling included samples collected from the Bond well (inactive), Jemez well (inactive), the junior high school tap water, the Rio Grande irrigation well, and the Santa Clara Pueblo community supply well. PCE and TCE were detected in the Bond well at maximum detected concentrations of 14.3 µg/L (micrograms per liter) and 2.3 µg/L, respectively. The Jemez well contained concentrations of PCE and TCE at 102 µg/L and 8.3 µg/L, respectively. No contaminants were detected in the Rio Grande irrigation well, the Santa Clara Pueblo community supply well, or junior high school tap water [2].

In the past, the Bond and Jemez wells were part of the public water supply system that provided drinking water to individuals residing within the City of Española. Individuals residing on the Santa Clara Pueblo did not receive drinking water from the City of Española public water supply system. Groundwater samples from the Bond and Jemez wells were first analyzed for VOCs in 1989. The contamination of these wells was discovered at this time and the wells were removed from use. Concentrations of contamination in these wells prior to 1989 are unknown. Prior to 1989, individuals served by the public water supply may have been exposed to chemicals in drinking water, principally through ingestion. More limited exposure may have resulted from inhalation (during showering and bathing) and through direct contact with skin, also referred to as dermal contact. The Bond and Jemez wells are currently not used as a drinking water source and future potable use of these wells is not planned. When the wells were in service, water was pumped directly into an interconnected distribution system. Users nearest the Bond and Jemez wells may have received water from just one of those wells at times, with little or no mixing. At other times, water from the Bond and Jemez wells mixed with water from other pumping wells. Because the wells had been used intermittently during their service and the onset of groundwater contamination and variability of concentrations are unknown, the actual concentrations of contaminants to which users may have been exposed to in the past are not known.

As previously discussed, groundwater data are not available prior to 1989. Therefore, the frequency, duration, and concentrations of contaminants that individuals may have been exposed to in drinking water are unknown. Several groundwater modeling analyses (groundwater and contaminant transport) have been undertaken at the NRAP site for the purpose of characterizing and better understanding groundwater and water-quality conditions that may have existed in the past and that may exist in the future. Detailed descriptions of the modeling analyses are presented in Appendix D of this document. A summary of the modeling analyses is presented below.

  • Three-dimensional groundwater flow and contaminant transport (advection-dispersion) modeling was conducted by Duke Engineering and Services, Inc. to determine the feasibility of different cleanup alternatives for the site [5].

  • Migration of the dissolved PCE in the shallow groundwater aquifer at Española, New Mexico was simulated by analytical models. Two-dimensional fate and transport modeling, using the analytical contaminant transport analysis system (ACTS) software, was conducted by ATSDR to estimate the concentration of the contaminants at the Jemez well and the length of time that individuals may have been exposed to contaminated drinking water. The Jemez well was selected as a point of reference because it has been more heavily impacted by contamination than the Bond well.

  • In an attempt to narrow the uncertainty associated with the concentration of the PCE source, a one-dimensional analytical parameter estimation model, CXTFIT was used to determine the most likely values for fate and transport parameters (including source concentration) based on field data [2,5] and published data (Appendix D).
  • Analytical model simulation using a best-fit analysis indicates that the onset of PCE contamination at the Jemez well occurred at about 2,200 days (or approximately 6 years) from PCE migration within the shallow aquifer [6]. Thus, human exposure to PCE-contaminated groundwater from the Jemez well probably occurred for approximately 14 years (1976 to 1989). The results of simulation and field data indicate that concentrations at the Jemez well during its operation were potentially in the range of 100 µg/L to 500 µg/L. Analysis of mechanisms for PCE contamination of the Jemez well, based on data collected at observational (or monitoring) wells and simulations, indicates that PCE migration within the shallow aquifer was not likely to be the primary mechanism for the intrusion of PCE and its related degradation products into the Jemez and other water supply wells in the Española area. Rather, pumping at the Jemez well and other nearby water supply wells facilitated vertical migration (or movement) of PCE and its degradation products into the upper deep and deep groundwater units or aquifers.

In addition to public well data and information gained from groundwater modeling efforts, groundwater samples were also collected from monitoring wells installed in the area of the NRAP site. Monitoring wells are not used for drinking water purposes and are instead used to evaluate the extent of groundwater contamination. Data was collected from two monitoring wells [R-09(I2) and R-15(D1)], in the vicinity of the Bond and Jemez wells, from 1992 to 1999. The Bond and Jemez wells are at a depth of approximately 100 and 260 feet, respectively. Monitoring well R-09(I2) is approximately 100 feet deep and is located about 200 feet southwest of the Jemez well. Monitoring well R-15(D1) is approximately 200 feet deep and is located about 600 feet southeast of the Jemez well. Although the monitoring well data does not indicate the concentrations that individuals were exposed to in the past as a result of contaminated drinking water, PCE and TCE concentrations measured in the monitoring wells are the maximum detected concentrations in the groundwater in vicinity of the Bond and Jemez wells. Therefore, this data has been considered in the evaluation of exposure to contaminated drinking water in this PHA for conservatism. The maximum detected concentrations of contaminants associated with the monitoring wells is 570 µg/L of PCE in monitoring well R-15(D1) and 24 µg/L of TCE in monitoring well R-09(I2).

Table 1 presents the contaminants that have been detected above established CVs in samples collected from the public water supply and associated monitoring wells.

Table 1.

Public Water Supply Sample Results and Associated Monitoring Well Data (µg/L)
Contaminant Bond Well Jemez Well Monitoring Well Data1 Tap Water CV CV Source
Max. FOD Max. FOD Max.
PCE 14 2/2 102 3/3 570 100
5
RMEG (child)
MCL
TCE 2.3 2/3 8.3 3/3 24 0.090
5
CREG
MCL

Notes:
1 PCE data is from monitoring well R-15(D1) (approximate depth: 200 feet) and TCE data is from monitoring well R-09(I2) (approximate depth: 100 feet). These detections are the maximum detected concentrations of PCE and TCE in deep monitoring wells. These monitoring wells are located in the vicinity of the Bond (approximate depth: 100 feet) and Jemez (approximate depth: 260 feet) wells.
µg/L = micrograms per liter
Max. = maximum detected concentration
FOD = frequency of detection = number of samples in which the chemical was detected/total number of samples
CV = Comparison Value
RMEG = Reference Media Evaluation Guide
CREG = Cancer Risk Evaluation Guide
MCL = maximum contaminant level

Based on the groundwater samples previously collected from the Bond well (1989 to 1991), Jemez well (1989 to 1991), and associated monitoring wells (1992 to 1999), exposures were evaluated to determine the likelihood of human health effects. Adult and child exposure doses were calculated for the concentrations of contaminants based on the maximum detected concentration in groundwater in the vicinity of the Bond and Jemez wells (PCE = 570 µg/L, TCE = 24 µg/L). For adults, an exposure duration of 14 years (based on the available data and groundwater modeling efforts) to 20 years (worst-case scenario; assumes exposure from the time that operations began at the Norge Town facility) was incorporated into the calculations. The exposure doses incorporated several conservative assumptions, including the assumption that no mixing or possible dilution of contaminant concentrations occurred. These assumptions may have resulted in an overestimation of potential exposure to individuals. A complete discussion of the assumptions utilized in the calculations is provided in Appendix C.

PCE

An evaluation of the available PCE data for the Bond and Jemez wells, and associated monitoring wells indicate that the estimated doses via ingestion for adults [0.016 milligrams per kilogram per day (mg/kg/day)] and children [0.036 mg/kg/day] are slightly above the established health guideline of 0.010 mg/kg/day. The health guideline is the EPA's Reference Dose (RfD), which is based on a study of mice that indicated no health effects at 14 mg/kg/day and liver effects at 70 mg/kg/day [7]. The concentration of PCE associated with liver effects in the study is hundreds of times greater than the calculated exposure doses. ATSDR's acute (or short-term) Minimal Risk Level (MRL) for PCE is 0.050 mg/kg/day, based on a short-term (one-week) study of mice that reported evidence of development neurotoxicity at exposure doses of 5.0 mg/kg/day, which is significantly greater than the exposure doses calculated for groundwater associated with the NRAP site [8].

Animal studies of PCE exposure resulting from ingestion have reported kidney effects. In addition, a study of mice and rats reported liver cancer among exposed mice. Animal subjects in these studies were exposed to doses of PCE that were thousands of times greater than the doses from contaminated drinking water exposure associated with the NRAP site [9].

According to EPA's Science Advisory Board, the available scientific evidence confirms that PCE exposure has been associated with the development of cancer in animals based upon three types of cancer in two species studied. These include liver tumors in male and female mice (but not rats), kidney tumors in male rats, and possibly, leukemia in male and female rats. Complications within each study and in their biological interpretations have made it difficult to understand the cancer-causing potential of PCE [10]. The final EPA cancer classification for PCE is currently under review. The available data suggest PCE is classified on the continuum of "possible" to "probable" human carcinogen.

A discussion of the available human studies is presented in the "Human Health Studies of PCE and TCE" subsection.

TCE

The samples collected from the Bond well (1989 to 1991), Jemez well (1989 to 1991), and associated monitoring wells (1992 to 1999) were considered in the evaluation of TCE exposure in drinking water. Exposure doses for adults and children have been calculated for the concentrations of TCE based on the maximum detected concentration of TCE in the groundwater in the vicinity of the Bond and Jemez wells, which was 24 µg/L from monitoring well R-09(I2).

The evaluation of the TCE concentrations detected in groundwater indicates that the estimated doses via ingestion for adults (0.00070 mg/kg/day) and children (0.0020 mg/kg/day). The calculated doses for adults and children exceed the EPA provisional RfD of 0.00030 mg/kg/day [13]. Studies used in the derivation of the EPA provisional RfD and other studies have reported an association between TCE exposure and the development of liver, kidney, and developmental effects at doses thousands of times greater than those calculated for exposure to drinking water contaminated with TCE in proximity to the NRAP site [14,15].

The EPA cancer classification for TCE is also under additional review by EPA. Animal studies indicate kidney cancer in rats and liver cancer in mice exposed to TCE. In the majority of these studies, animal subjects were exposed to very high concentrations of TCE [15,16].

A discussion of the human health studies regarding TCE exposure is presented in the "Human Health Studies for PCE and TCE" subsection that follows.

Human Health Studies for PCE and TCE

The results of several studies of human exposure to PCE and TCE in the drinking water supply have been reviewed. The studies provide some information on the cancer and non-cancer health effects associated with exposure to humans. These studies are discussed in the following paragraphs.

A study was conducted at the U.S. Marine Corps Base Camp LeJeune in North Carolina that examined adverse pregnancy outcomes associated with exposure to VOCs, including PCE and TCE, in the drinking water supply. Although the actual concentrations that women were exposed to and the duration of their exposure are unknown, concentrations of PCE and TCE in the water supply may have been as high as 215 µg/L and 1,400 µg/L, respectively. Estimates indicate that exposure may have occurred for over 25 years. The study concluded that women over 35 years of age that were exposed to PCE and TCE were 4 times more likely to have infants that were small for gestation age. Only a slightly increased incidence was observed among the entire study group of women [17]. ATSDR is currently conducting a more extensive study of this community [18].

Residents of Woburn, Massachusetts were exposed to drinking water contaminated with VOCs, including PCE at concentrations of 21 µg/L and TCE at concentrations of 250 µg/L or greater. The findings of one of the studies of this community indicated that developmental anomalies related to the central nervous system, chromosomes, and oral cleft were associated with exposure [19]. However, the scientific community has noted limitations with this study regarding the biological relevance of grouping these anomalies for the purpose of statistical analysis. As a result, the findings of this study are difficult to interpret and apply to other exposed individuals [11]. Studies of the exposed individuals in Woburn have also reported an association between exposure to contaminated drinking water and an increased risk of childhood leukemia [19,20,21]. Numerous studies have evaluated the findings of the Woburn study and have identified several shortcomings (for example, lack of information on exposure doses, duration of exposure, and the fact that several of the leukemia cases reported in the study did not have access to the contaminated drinking water) [11,22,23,24,25,26].

In response to an increased incidence of childhood cancer in Dover Township, New Jersey, a study evaluated potential community exposures to toxic chemicals in the environment. Chemicals, which include PCE, TCE, and various other contaminants, were detected in the area's drinking water supply. In addition, contaminants were also likely to be present in the air as a result of emissions from the nearby hazardous waste sites. The results of the study indicate an increased risk of leukemia among young females via prenatal exposure to contaminants in the drinking water supply and exposure to contaminants present in the air. Several uncertainties exist regarding this study, such as the potential exposure to various contaminants, limited available groundwater and air data, and lack of information on exposure doses and duration [27].

ATSDR reviewed another study of birth outcomes in 75 towns in New Jersey, where individuals ingested drinking water contaminated with VOCs, including PCE and TCE [28]. The study concluded that oral cleft defects were elevated. Several limitations have been identified in the study, such as confounders (smoking, additional occupational exposures, medical history), which do not allow for the results of this study alone to conclude definitively on the association between developmental effects and exposure [11]. A review of the available scientific data indicates that further study of the likelihood of the contaminants to result in development effects is necessary. Another study of these New Jersey communities reported an increased incidence of childhood leukemia and non-Hodgkin's lymphoma in females exposed to greater than 5.0 ug/L of TCE in drinking water [29]. Limitations of the studies include lack of information regarding contaminant levels, exposure duration, and water consumption variations among individuals.

A review of the available studies of PCE exposure via inhalation indicates that PCE and TCE has been associated with liver, kidney, neurological, developmental effects, and leukemia among subjects exposed to very high concentrations [11,14]. Studies have reported skin effects, such as chemical burns and blistering from prolonged exposure to concentrated PCE and TCE used in dry cleaning operations [12,14]. Exposure to PCE and TCE via inhalation and dermal contact is expected to be significantly lower than among study subjects. Although ingestion is the major route of exposure, individuals may also have been exposed to PCE and TCE via inhalation and dermal contact during showering.

ATSDR maintains the TCE exposure subregistry, which compiles health-related information from the nearly 5,000 participants that have been exposed to TCE from contaminated drinking water [30]. The participants were exposed to TCE concentrations ranging from 2.0 µg/L to 24,000 µg/L (or 0.002 mg/L to 24 mg/L) for up to 18 years. Studies of this population indicate that individuals exposed to TCE may have an increased incidence of health effects, particularly stroke. Other health effects reported among participants of the TCE subregistry include anemia, urinary tract disorders, liver and kidney effects, diabetes, and skin conditions. Based on the available information, a cause-effect relationship has not been demonstrated between TCE exposure and the reported health effects. Studies of the participants of the subregistry and the potential for health effects related to TCE exposure are ongoing.

In summary, some uncertainties exist in the available scientific literature regarding levels of PCE and TCE associated with health effects and the actual exposure to individuals residing within the City of Española who received drinking water from the public water supply. However, the available information from groundwater samples collected from the public water supply wells (Bond and Jemez wells), nearby monitoring wells, and the groundwater modeling efforts support the possibility that individuals may have been exposed to elevated concentrations of contaminants in the public water supply. Therefore, ATSDR concludes that an increased risk of health effects may have existed for children and the developing fetus, who were exposed to contaminants in drinking water provided by the City of Española in the past (prior to 1989) primarily due to ingestion. Health effects of concern are developmental effects and childhood leukemia.

It should be noted that individuals residing on the Santa Clara Pueblo did not receive their drinking water from the public water supply within the City of Española in the past. Individuals residing on the Santa Clara Pueblo received their water from private wells and Pueblo community supply wells. Therefore, these individuals were not exposed to contaminants from the Bond and Jemez wells.

Private Well Water

Individuals residing within the City of Española receive their drinking water from the public water supply. Some city residents have private wells that may be utilized for non-drinking water uses, such as watering lawns and gardens, or filling swimming pools. Residents of the Santa Clara Pueblo receive their drinking water from private wells and the community water supply. In order to evaluate the potential impact of contamination, groundwater samples were collected from private wells in the City of Española and wells located directly adjacent to Santa Clara Pueblo Trust Land.

Seven private irrigation (non-drinking) wells in the site vicinity and within the City of Española were sampled from 1991 to 1998. It is unknown whether these private wells were impacted by the PCE groundwater plume prior to 1991, because no sample data is available. PCE, TCE, chloroform, and 1,2-dichloroethane (1,2-DCA) were detected in some of the samples collected from the private wells. Only one private well was found to contain concentrations of PCE and TCE. This well is not currently in use by the property owner. No contaminants were detected in the one inactive, private residential well within the City of Española, which was previously used for drinking water purposes.

Samples were also collected (1998-1999) from twelve active, private, drinking water wells, which are located directly adjacent to Santa Clara Pueblo Trust Land. Based on the sample results, no contaminants were detected in the twelve private wells that were sampled [2]. Although data is not available prior to 1998, the available information indicates that wells located directly adjacent to Santa Clara Pueblo Trust lands were not impacted by contamination in the past and exposure is not likely in the future. Therefore, no health effects are expected to occur.

Table 2 presents the COCs that have been selected for groundwater from private wells.

Table 2.

Groundwater Sample Results - Private Wells (µg/L)
Contaminant Seven Irrigation Wells Tap Water CV CV Source
Max. FOD
Chloroform 39 2/17 6 CREG
1,2-DCA 2.0 1/17 0.4 CREG
PCE 56 4/14 100
5
RMEG (child)
MCL
TCE 37 4/17 0.090
5
CREG
MCL

Notes:
µg/L = micrograms per liter
Max. = maximum detected concentration
FOD = frequency of detection = number of samples in which the chemical was detected/total number of samples
CV = Comparison value
CREG = Cancer Risk Evaluation Guide
RMEG = Reference Media Evaluation Guide
MCL = maximum contaminant level

Residents using their private wells for non-drinking purposes may have been exposed in the past, may be exposed at this time, or may be exposed in the future to chemicals present in groundwater. Ingestion of water from irrigation wells is not known to have occurred and is unlikely in the future, because individuals with these wells receive public water for drinking purposes. Although it is possible for individuals to inhale contaminants that have volatized from groundwater used for irrigation purposes or swimming pools, these exposures are not expected to be significant due to the large quantities of outdoor air that dilute the contaminants that have become airborne. Incidental ingestion of water during swimming is also possible, but exposure is considered very limited due to the minimal amount of water expected to be ingested and the concentration of contaminants present in the water. Therefore, the evaluation of exposure to private well water focuses on exposure via direct (or dermal) contact while swimming in pools that have been filled with water from private wells. This is considered a protective approach because individuals are likely to have more limited contact with the water from private wells during irrigation activities (for example, less surface area exposed, shorter exposure duration in comparison to swimming).

Dose estimates were calculated for exposure to PCE, TCE, chloroform, and DCA in order to evaluate the potential for adverse health effects to result from direct contact with water from non-drinking water wells. Exposure evaluation was conducted using the maximum detected concentrations of contaminants. A complete discussion of the assumptions utilized in the calculations is provided in Appendix C.

Chloroform

Based on the available information, adverse non-cancer and cancer health effects are not expected to a result from direct contact of children or adults to chloroform during irrigation activities or swimming in pools that have utilized water from private non-drinking water wells. The estimated doses are 0.00040 mg/kg/day and 0.0019 mg/kg/day for adults and children, respectively, which do not exceed the established health guideline of 0.010 mg/kg/day. The health guideline is the ATSDR's oral MRL and EPA's oral RfD, which is based on an animal study that reported liver effects at concentrations that were hundreds of times greater than those associated with exposure to chloroform during private well water use [31]. Based on the available scientific literature, there are no human studies that evaluate exposures specifically to chloroform because it exists in addition to other disinfection byproducts that may contribute to exposure in many of the available studies [31].

Although no cancer data exists for direct contact, chloroform is considered to be cancer-causing at very high doses via direct contact because it is absorbed through the skin, is metabolized, and is likely to cause toxicity in much the same way as chloroform absorbed by other exposure routes [13]. EPA has categorized chloroform as a probable human carcinogen, based on "sufficient evidence" of carcinogenicity in animals [13]. The doses of chloroform that have been associated with liver and kidney tumor production in the available animal data are thousands of times greater than those resulting from exposure to private well water for non-drinking water purposes [13,31,32,33,34,35,36,37]. Therefore, adverse health effects are not expected to occur as a result of exposure to groundwater from private drinking water wells that are used for non-drinking water purposes.

1,2-DCA

Adverse health effects are not likely to be associated with adult and childhood exposure via direct contact with 1,2-DCA present in private well water during non-drinking water uses. The estimated doses are 0.0000008 mg/kg/day and 0.0000040 mg/kg/day for adults and children, respectively, are well below the established health guideline of 0.20 mg/kg/day. The health guideline is ATSDR's oral MRL, which is based on an animal study that reported kidney effects at concentrations that were thousands of times greater than those associated with exposure to 1,2-DCA during private well water use [38].

There is limited human data regarding the cancer-causing potential of 1,2-DCA in humans. EPA has categorized 1,2-DCA as a probable human carcinogen, based on "sufficient evidence" of carcinogenicity in animals [13]. High level 1,2-DCA exposure has been associated with cancer through ingestion, inhalation, and direct contact. Exposure to 1,2,-DCA via private well water use for non-drinking purposes is assumed to occur only by direct contact with the water. The findings of one mice study indicates that exposure to 1,2-DCA at very high concentrations can penetrate the skin, can be absorbed, and has been associated with the production of cancer [37]. However, the concentrations associated with exposure to private well water in the vicinity of the NRAP site are very low concentrations and are not expected to produce health effects.

PCE

Health effects are not expected to occur among individuals exposed to PCE in private well water resulting from non-drinking water uses. The doses calculated for adults and children exposed to PCE via direct contact with groundwater from private wells while swimming does not exceed the established health guidelines. The calculated doses are 0.0015 mg/kg/day and 0.0077 mg/kg/day for adults and children, respectively. The health guideline of 0.010 mg/kg/day is both EPA's oral RfD and ATSDR's oral MRL and is based on liver effects in mice at doses greater than 70 mg/kg/day. The doses observed in the study that result in liver effects is thousands of times greater than the calculated doses for direct contact with private well water [7]. According to ATSDR's toxicological profile, the available scientific data indicates that health effects have not been reported at doses less than 70 mg/kg/day and the majority of health effects have been observed at doses greater than 100 mg/kg/day [11]. Studies of direct contact by workers indicate burning and blistering among individuals whose skin was directly exposed to very highly concentrated PCE [39,40,41,42]. Exposures associated with private well water use are not expected to result in adverse health effects due to the low concentrations of PCE present.

Information on the cancer-causing potential of PCE is currently under review. While there are some data to support each classification, it is being decided whether PCE should be designated as a possible human carcinogen or a probable human carcinogen. The U.S. Department of Health and Human Services has determined that PCE may reasonably be anticipated to be a carcinogen, based on studies reporting liver tumors in mice and kidney tumors in male rats [11]. There is very limited data on the potential for direct PCE exposure to result in cancer. One mice study reported no skin tumor production following the application of high concentrations of PCE on the skin of animals over approximately a 20-month period [37]. As with the studies available for non-cancer health effects, cancer studies indicate effects at doses greater than 100 mg/kg/day, which is thousands of times greater than the doses calculated for individuals exposed to PCE in private well water utilized for non-drinking water purposes. Therefore, health impacts are not expected as a result of exposure to PCE in private wells used for non-drinking water purposes.

TCE

Based on the available information, adverse non-cancer and cancer health effects are not expected to a result from direct contact with contaminants of children or adults to TCE during irrigation activities or swimming in pools that have utilized water from private (non-drinking water) wells. Limited health guideline information is available for the evaluation of direct contact with TCE. The estimated doses are 0.00060 mg/kg/day and 0.0031 mg/kg/day for adults and children, respectively, which do not exceed the available health guideline of 0.20 mg/kg/day. The health guideline used in this evaluation is ATSDR's oral MRL for acute exposure (less than 14 days), which is based on an animal study that reported developmental effects at concentrations thousands of times greater than those associated with exposure to TCE during private well water use [14]. The EPA provisional RfD of 0.00030 mg/kg/day (based on ingestion exposure) has been developed and may be updated upon completion of additional studies. Occupational studies have indicated skin effects, such as dermatitis, irritations, and rashes, as a result of direct contact with highly concentrated solutions of TCE (approximately 90%-98% undiluted TCE). The concentrations of TCE reported in the available occupational studies are significantly higher than those that may be present in private well water. Therefore, it is not likely for skin effects to occur based on direct contact with TCE concentrations in water from private wells [43,44,45,46,47].

Consensus has not been reached by the scientific community regarding the cancer-causing potential of TCE. EPA is currently re-evaluating the available scientific literature on the potential for TCE exposure to result in various types of cancer [13]. The International Agency for Research on Cancer (IARC) has classified TCE as a probable carcinogen in humans, based on the available animal studies [48]. The American Conference of Governmental Industrial Hygienists (ACGIH) has categorized TCE as not suspected as a human carcinogen [49]. However, the data in humans are considered inconclusive [50]. Few studies are available regarding direct contact with TCE. The available data indicates that workers directly exposed to very high concentrations of TCE on their skin and also exposed by inhalation of TCE experienced increased incidence of stomach, liver, prostate, and lymphohematopoietic cancers [51]. The concentrations that workers were exposed to in the study were significantly higher than those expected among individuals that are in direct contact with water from private wells. Additionally, an animal study of direct contact with TCE reported no cancerous effects from high-level exposure [37]. Based on the concentrations of TCE that individuals are likely to be exposed to from private well water use for non-drinking water purposes, health effects are not expected to occur.

To summarize, ATSDR concludes that cancer and non-cancer health effects are not expected to results from direct contact with chemicals present in groundwater from private wells within the City of Española that are used for non-drinking water purposes, such as irrigation or the filling of swimming pools.

Potential Exposure Pathways

Indoor Air

Volatile contaminants from groundwater may be released as a vapor to the overlying soil (soil gas) and migrate through the soil to the ground surface. Therefore, some of the VOCs present in the shallow PCE plume may migrate upwards toward the ground surface, and may enter buildings through utility openings and floor cracks or similar defects. As a result, concentrations of contaminants in groundwater beneath the building may be present in indoor air in buildings and residences overlying the contamination. To determine whether individuals might be exposed to contaminants in indoor air, samples were collected from properties overlying the PCE plume in 1999, including the Las Cumbres Learning Services, Inc. office and classroom, and a private residence on Chavez Street. An indoor air sample was also collected from the library of the junior high school, which is located several hundred feet east of the PCE plume. No contaminants were detected in indoor air samples collected from the Las Cumbres Learning Services, Inc. classroom and the junior high school library.

The contaminants, whose concentrations exceed the established CV and were selected as COCs in indoor air, are presented on Table 3 and discussed in the following text.

Table 3.

Indoor Air Sampling Results (milligrams per cubic meter [mg/m3])
Contaminant Las Cumbres, Office Private residence on Chavez Street Ambient Air CV CV Source
1,1-DCE 1.1 ND 0.000020
0.020
0.20
CREG
Int. EMEG/MRL
RfC
1,2,4-TMB ND 0.070 0.0062 RBC/PRG

Notes:
mg/m3 = milligrams per cubic meter
CV = Comparison Value
ND = not detected
Int. = intermediate
EMEG = Environmental Media Evaluation Guide
MRL = Minimal Risk Level
CREG = Cancer Risk Evaluation Guide
RfC = Reference Concentration
RBC = Risk-Based Concentration
PRG = Preliminary Remediation Goals

1,1-Dichloroethene (1,1-DCE)

1,1-Dichloroethene (1,1-DCE) was detected at a concentration of 1.1 milligram per cubic meter (mg/m3) at the office at the Las Cumbres Learning Center, Inc. in September 1999. No VOCs were detected in a sample collected from a classroom at the Las Cumbres Learning Center on the same day. Three subsequent follow-up samples were collected at the office area and analyzed for VOCs. The follow-up sampling indicated that 1,1-DCE and the other VOCs analyzed for were not present in the samples [52]. Therefore, additional evaluation of 1,1-DCE in indoor air at the Las Cumbres Learning Services, Inc. office was not conducted. Exposure to 1,1-DCE is not considered likely and, therefore, health effects are not expected.

1,2,4-Trimethylbenzene (1,2,4-TMB)

1,2,4-Trimethylbenzene (1,2,4-TMB) was detected in an indoor sample collected from a private residence located on Chavez Street at a concentration of 0.070 mg/m3. It is likely that 1,2,4-TMB concentrations in this sample are not related to the contamination in the PCE plume. Gasoline products, some paints, paint thinners, and other household products have been known to contain concentrations of 1,2,4-TMB. Limited human toxicological data is available to evaluate exposure to 1,2,4-TMB. A study of workers chronically exposed to solvents containing 1,2,4-TMB and other chemicals reported respiratory and central nervous system effects from exposure to very high concentrations (50 mg/m3 to 300 mg/m3), which are hundreds to thousands of times greater than the 1,2,4-TMB concentrations detected in the house on Chavez Street. No carcinogenic evaluation is available to evaluate exposure to TMB [13].

Based on the available data, ATSDR concludes that individuals are not likely to experience cancer and non-cancer health effects due to contaminants in indoor air associated with the NRAP site.

Outdoor Air

There is some potential for exposure to outdoor air containing chemicals that overlie shallow groundwater contamination. Contaminants present in the shallow groundwater plumes may migrate upwards toward the ground surface and may also enter the outdoor air. Contaminant concentrations released to outdoor air will typically be reduced quickly as a result of dilution with large quantities of outdoor air.

Two outdoor air samples were collected from areas overlying the groundwater plume in 1999. Sample locations include the play area at Las Cumbres Learning Services, Inc. and near the lint trap (source) at the Norge Town facility. Table 4 presents the contaminants that have been detected above CVs in outdoor air samples and evaluated further in this PHA.

Table 4.

Outdoor Air Sampling Results (mg/m3)
Contaminant Las Cumbres, Play Area Lint trap at Norge Town Facility Ambient Air CV CV Source
PCE ND 0.98 0.040 Chronic EMEG/MRL
1,2,4-TMB 0.18 ND 0.0062 RBC/PRG

Notes:
mg/m3 = milligrams per cubic meter
CV = Comparison Value
ND = not detected
EMEG = Environmental Media Evaluation Guide
MRL = Minimal Risk Level
RBC = Risk-Based Concentration
PRG = Preliminary Remediation Goal

PCE

PCE was detected in the outdoor air near the lint trap at the Norge Town facility (source) at a concentration of 0.98 mg/m3, which exceeded the lowest established CV. The liver and nervous system are the primary target organs for humans exposed to high concentrations of PCE via inhalation [40,53,54,55,56]. Severe respiratory, kidney, and liver effects have been reported among humans exposed to high concentrations of PCE (greater than 6,000 mg/m3) [11,57,58]. In a study published by the National Institute for Occupational Safety and Health, individuals were exposed to concentrations of PCE ranging from 0 to approximately 1,000 mg/m3 for 7.5 hours per day, 5 days per week, or 1 week. The study concluded that no adverse pulmonary, liver, or kidney effects were observed among these individuals [57]. The concentration of PCE associated with exposure to outdoor air overlying the groundwater plume is thousands of times less than the concentrations associated with health effects. Therefore, no adverse health effects are likely from exposure to PCE in outdoor air.

As previously discussed, the carcinogenic classification of PCE is currently under EPA review. The available data are primarily studies of workers exposed to concentrations much greater than concentrations of PCE detected in outdoor air in the vicinity of the Norge Town facility. The findings from animal and human health studies provide some evidence for PCE carcinogenicity in animals and limited evidence for carcinogenicity in humans. There is little consistency between the types of cancers reported in animals and humans, suggesting that there is not a common outcome for PCE exposure. However, based on the available data, an increased risk of cancer is not likely to result from inhalation exposure to PCE in outdoor air overlying the PCE plume.

1,2,4-TMB

1,2,4-TMB was detected at 0.18 mg/m3 in outdoor air samples collected from the Las Cumbres Learning Services, Inc. play area. Based on the available information, TMB in the outdoor air is not expected to be the result of contamination at the Norge Town facility, as gasoline, paints, and other products may emit this contaminant into the air. As previously discussed, there is very little available data for the evaluation of 1,2,4-TMB exposure. The available occupational studies indicate respiratory and central nervous system effects from inhalation of 1,2,4-TMB at concentrations that are hundreds to thousands of times greater than those indicated from the outdoor air samples collected as part of the investigation at the NRAP site. No carcinogenic evaluation is available to evaluate exposure to TMB [13].

ATSDR concludes that, based on the available air data, individuals exposed to contaminants in outdoor air are not expected to experience adverse non-cancer effects or an increased risk of cancer as a result of exposure.

Additional Exposure Pathways Considered and Excluded

ATSDR considered several exposure pathways and excluded them from further evaluation. Review of the available information for these pathways indicated that they do not pose a public health threat. A brief rationale for the exclusion of these pathways is provided below. These pathways include the following:

On-Site Soils

Subsurface soil samples were collected from 23 locations in the area adjacent to the lint trap at the Norge Town facility at depths ranging from 1 to 5 feet deep. Samples were collected during several investigations conducted in 1996, 1998, and 1999. Very low levels of VOCs were detected in subsurface soil [2]. The results of the data indicate that none of the samples contained concentrations of VOCs that exceed the established soil CVs. Therefore, no additional evaluation of VOCs was conducted for exposure to on-site soils. Arsenic was also detected in soil. Arsenic is not expected to be site-related and is present at typical naturally-occurring concentrations. Therefore, exposure by adults and children of the community has not been evaluated further in this PHA.

Off-Site Soils

Subsurface soil samples were also collected from four locations adjacent to Las Cumbres Learning Services, Inc. in 1999. The samples were collected at depths ranging from 1 to 5 feet deep. Four subsurface soil samples were collected on the Santa Clara Pueblo at depths ranging from 1 to 4 feet deep [2]. No contaminants were detected above CVs in off-site soil. Additionally, future impact to off-site soil is not expected to occur.

Surface water

Eleven surface water samples were collected from the Santa Clara Ditch, the Guachupangue Arroyo, and the Rio Grande in 1996, 1998, and 1999. None of the contaminants associated with the NRAP site were detected in surface water samples above CVs [2]. In addition, future remediation efforts at the site are expected to greatly reduce soil and groundwater contamination in the area. Therefore, surface water is not likely to be significantly impacted and health effects via exposure to surface water are not expected to occur under future conditions.

Sediment

Six sediment samples were collected from the Rio Grande and associated drainage ditches in 1996, 1998, and 1999. No contaminants were detected above CVs [2]. As previously discussed, the proposed remediation efforts are expected to minimize the introduction of contamination to the surface water and sediment in the future. Therefore, future exposure to sediment is not expected to result in health effects.

Fish Consumption

Contaminants have not been detected in surface water in the vicinity of the NRAP site. It should also be noted that PCE and TCE have not been found to readily accumulate in fish tissue [11,14].

Plant Uptake

PCE and TCE have not been found to readily accumulate in plants [11,14].

Animal Uptake

PCE and TCE have not been found to readily accumulate in animals [11,14].

ATSDR Child Health Initiative

To ensure that the health of the nation's children is protected, ATSDR has implemented an initiative to protect children from exposure to hazardous substances. ATSDR recognizes that the unique vulnerabilities of infants and children demand special emphasis in communities faced with contamination of their water, soil, air, or food. Infants and children are usually more susceptible to toxic substances than adults due to their immature and developing organs. Children are smaller, which results in higher doses when compared with adults. Most importantly, children depend completely on adults for risk identification and management decisions, housing decisions, and access to medical care. ATSDR's evaluation contained within this document considered children as a susceptible subpopulation.

Children and the developing fetus may have been exposed to contaminants, particularly PCE and TCE, present in the public water supply prior to 1989. To a much lesser extent, children may have been exposed in the past or may currently be exposed to contaminants as a result of swimming in pools that have been filled with water from private (non-drinking water) wells. Exposure to children from non-drinking water uses has been evaluated in this PHA and ATSDR concludes that health effects are not expected to occur. The potential for health effects among children exposed in the past to contaminated drinking water is discussed below.

Several studies have reported adverse health effects, primarily developmental effects among babies born to women exposed to PCE, TCE, and other contaminants in the drinking water supply during their pregnancies. Limited studies also suggest an association between PCE and TCE exposure and an increased risk of childhood leukemia. These studies have many limitations, such as lack of information on exposure duration and frequency. In addition, some important information is also unavailable for the NRAP site, such as the data on the concentrations of PCE and TCE prior to 1989 and the length of time that individuals were likely to be exposed. However, based on the available data, groundwater modeling efforts and an interpretation of the available scientific literature, past exposure to contaminated drinking water from the Bond and Jemez wells may have resulted in an increased risk of developmental effects, and possibly childhood leukemia.

Health Outcome Data Evaluation

Health outcome data may help determine whether the incidence rates of certain adverse health effects are higher than expected in the area potentially affected by a site. ATSDR conducts a review of health outcome data when the toxicological evaluation of a completed exposure pathway indicates the likelihood of adverse health outcomes. The evaluation of health outcome data may give a general picture of the health of a community, or it may confirm the presence of excess disease or illness in a community. However, elevated rates of a particular disease may not necessarily be caused by hazardous substances in the environment. Other factors, such as personal habits, socioeconomic status, and occupation, may also influence the development of disease. In contrast, even if elevated rates of disease are not found, a contaminant may still have caused illness or disease.

The Superfund law requires that health outcome (for example, mortality and morbidity) data be considered in a PHA [59]. This consideration is done using specific guidance in ATSDR's PHA Guidance Manual and a 1996 revision to that guidance [4,60]. The main requirements for evaluating health outcome data are the presence of a completed human exposure pathway, high enough contaminant levels to result in measurable health effects, sufficient persons in the completed pathway for health effects to be measured, and a health outcome database in which disease rates for population of concern can be identified.

Birth weight data were not available for the period of interest (1970s and 1980s). Española city-level data was not available until the late 1980s. An accurate meaningful comparative analysis of low birth weight is not possible. For both 1989 and 1990, the percentage of low birth weight babies was approximately 9% for Española city, similar for Rio Arriba County (8%). Information for birth defects was not available for the period of interest. Other child health data were not routinely collected for the period of interest; therefore, a meaningful analysis is not possible.

Cancer rates for children and adults was considered, however; varying population estimates for Española 1970-2000 created a concern for producing accurate rates. New Mexico state health officials are trying to resolve this dilemma, until such time we are unable to provide accurate meaningful comparative cancer data.

Further, no direct relationship with the plume contamination would be drawn from this analysis of cancer data. Only the determination of whether rates of certain cancers in Española are more than usual, based on a comparison with an appropriate area (for example, state rates). This descriptive analysis is incapable of drawing a cause-effect relationship for the chemicals of concern. The major risk factors for human cancer in the United States are tobacco; dietary imbalances; and the ingestion of carcinogens, hormones, radiation (predominantly ultraviolet-induced skin cancer and radon-related pulmonary tumors), and viruses [61].

Community Health Concerns

ATSDR advertised and conducted two 1-hour meetings in early December 1998 at the Northern New Mexico Community College. The goal of the meeting was to have citizens meet with ATSDR staff and raise any health-related concerns about the site. In addition, some employees of the New Mexico Department of Health and some members of the Rio Arriba Environmental Health Association (EL RAEHA) steering committee attended.

In April 1999, ATSDR attended an EL RAEHA Steering Committee meeting. ATSDR staff from the Divisions of Health Assessment and Consultation and Health Education and Promotion presented background information about ATSDR, information on the PHA process, and possible options for community health education. Additional health-related concerns were expressed at this meeting.

ATSDR representatives also met with members of the Santa Clara Pueblo Tribal Council in July 2001. ATSDR's involvement at the site and some community concerns of the tribe were discussed during this meeting.

During the public comment period for this PHA, ATSDR plans to hold public meetings within the City of Española and on the Santa Clara Pueblo to gather any additional community concerns. Responses to these concerns will be addressed in the final version of this PHA. The community health concerns that have been received, to date, are paraphrased in the following text.

What health effects have been associated with ingestion of manganese in drinking water? Are residents in the vicinity of the NRAP site likely to be exposed to concentrations of manganese in groundwater that are harmful?

Manganese is a naturally occurring metal found in rocks. It has also been used in pesticides (maneb and mancozeb), as an additive in gasoline, and can be produced from the burning of fossil fuels. While manganese is an essential nutrient required for normal body function, too much manganese may result in illness. Conflicting human studies are available regarding the potential health effects of manganese exposure from ingestion. Most information regarding exposure via ingestion to manganese has been derived from animal studies. Studies in animals have shown that very high concentrations of manganese in food and water may result in neurological effects [62]. To avoid staining of clothing and plumbing fixtures, EPA recommends that the concentrations of manganese in drinking water not be more than 50 µg/L [62]. Municipal water supplies are expected to meet the EPA criteria, which ATSDR considers adequately protective of human health. Therefore, individuals that receive their drinking water from the public water supply are not likely to be exposed to concentrations of manganese above 50 µg/L.

Inhalation exposure to very high concentrations of manganese has been associated with several neurological effects. Long-term exposure to high concentrations of manganese, typically in the workplace, has been associated with a condition referred to as "manganism." The symptoms associated with manganism are similar to those experienced by individuals with Parkinson's disease. These symptoms include mental and emotional disturbances, muscle weakness, speech impairments, tremor, and other neurological effects.

Manganese has been detected in groundwater collected from monitoring wells in the vicinity of the NRAP site. Monitoring wells are not used for drinking water purposes, but rather for periodic sampling and evaluation of groundwater conditions. Manganese was detected during August 1998 groundwater sampling at concentrations ranging from non-detect to 2,890 µg/L. Based on the available information, it is not clear whether the manganese concentrations are naturally occurring, or whether manganese is present due to human activities, such as pesticide application or the impact of gasoline containing manganese as an additive. Manganese is not expected to be associated with site-related activities. It is recommended that private drinking water wells be sampled for manganese prior to use.

In the event that manganese was detected in private irrigation wells, individuals will not likely be exposed to significant concentrations of manganese. Due to its chemical properties, manganese present in water is not expected to volatile into air or to result in significant exposures through inhalation. Therefore, adverse health effects from exposure during irrigation well use are not likely to occur.

If plant foods are irrigated with contaminated waters, will I become ill from eating the plants?

The main contaminants of concern at the NRAP site are PCE and TCE. Based on the available data, these contaminants are not substantively absorbed and accumulated by vegetation [11,14]. Therefore, ATSDR does not believe that eating plants irrigated with contaminated former public or private well water is likely to be associated with adverse health effects.

Can contaminants in the groundwater cause persistent skin rashes?

Limited data is available regarding the effects of skin from direct contact with contaminants in groundwater. A human study of PCE concluded that direct contact with highly concentrated solutions of PCE was associated with burns, blistering, and other skin effects. However, no damage to skin has been reported in animals exposed chronically to PCE [11]. Skin irritations, burns, and rashes have been found to result from occupational exposure to TCE. The dermal effects are usually the consequence of direct skin contact with highly concentrated solutions, significantly higher than detected concentrations of TCE in the vicinity of the site [14]. The concentrations of PCE evaluated in the available studies are significantly greater than the concentrations in groundwater in the vicinity of the NRAP site.

Are houses located over, or near, the contaminated groundwater?

ATSDR staff observed commercial development and several homes present near and overlying the shallow PCE groundwater plume from its origin on North Railroad Avenue to Santa Clara Bridge Road (State Road 201). The local junior high school is located several hundred feet east of the shallow PCE groundwater plume.

What are the combined health effects for Española residents who may be exposed, in some manner, to the groundwater plume associated with the NRAP site and may also be exposed to Los Alamos National Laboratory contaminants or other contaminant sources in Española?

ATSDR reviewed the Environmental Protection Agency's Toxic Release Inventory (TRI) to determine if any additional sources of contaminants in Española, New Mexico were listed. The TRI database provides information about annual releases of toxic chemicals for many industrial facilities. The database does not include toxic release information for any facilities in Española, New Mexico. However, Los Alamos National Laboratory is in the vicinity of Española and past activities conducted at the site have generated both radioactive and chemical waste.

Currently, ATSDR is in the process of reviewing the available data for Los Alamos National Laboratory and preparing a PHA to evaluate potential exposures to contaminants present at the site. Upon completion, the PHA will be released to the public for comment. Potential health effects for Española residents exposed to contaminants associated with the NRAP site, as well as exposed to potential contamination at Los Alamos National Laboratory cannot be adequately assessed until the Los Alamos National Laboratory PHA has been completed.

If I use the water in my private well for non-drinking water purposes, such as filling a swimming pool, can my children become ill?

Based on the available data, adverse health effects are unlikely to occur from direct contact with contaminants (PCE, TCE) in private well water during non-drinking water uses, such as during irrigation and/or filling of a swimming pool. A complete discussion of this exposure pathway is addressed in the Discussion Section of this PHA.



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