PUBLIC HEALTH ASSESSMENT
LITCHFIELD AIRPORT AREA
(a/k/a PHOENIX GOODYEAR AIRPORT)
GOODYEAR, MARICOPA COUNTY, ARIZONA
3.0 ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
This public health assessment evaluates if a public health hazard exists to residents living near the PGA North site. To assess the potential adverse health effects of environmental contamination to the surrounding community near the PGA North site, the concentration of the contaminant in a specific medium (soil, air, or water) is compared to a screening value for that contaminant in that particular medium. The screening value is used to identify the chemicals that need to be evaluated in site-specific detail in the public health assessment.
There are several types of screening values which are dependent on the type of exposure pathway (dermal, ingestion, and inhalation) and the medium in which the contaminant is found (soil, air, or water). The screening levels are calculated using conservative health protective assumptions. These provide guidance in determining if the level of a chemical could present a public health hazard to nearby populations. If the concentration of the chemical is below the screening value, adverse health effects would not be expected. If the chemical concentration is above the screening value, then it is called a contaminant of concern (COC) and is further evaluated to determine if adverse health effects are likely to occur. The different screening levels used in this PHA are described below.
Soil Screening Levels
Site-specific soil contaminant concentrations are compared to Soil Remediation Levels (SRLs) to determine which soil contaminants will be evaluated further in the Public Health Assessment. SRLs for soil ingestion are calculated by ADHS, Office of Environmental Health using a human health-based approach that is generally consistent with risk assessment methodologies. SRLs protect against toxic doses of systemic toxicants, and limit excess lifetime cancer risk to one-in-one million (10-6) for known human carcinogens and to one-in-one hundred thousand (10-5) for possible and probable human carcinogens. ATSDR accepts the Arizona SRLs as an appropriate screening level that can be used for site purposes. Chemical concentrations in soils that exceed SRLs may not necessarily represent a health risk. Rather, when contaminant concentrations in soil exceed these standards, further evaluation may be necessary to determine whether the site poses an unacceptable risk to human health (ADHS 1997a).
Groundwater Screening Levels
Groundwater contaminants found in private wells were compared to the USEPA maximum contaminant levels (MCLs). The MCLs are enforceable drinking water regulations that are protective of public health to the extent feasible in public water supplies. If levels of contamination in a well were found above the MCL, then exposure intakes were calculated and compared to the ATSDR minimal risk levels (MRLs).
The selected list of contaminants of concern (COCs) indicates which contaminants will be evaluated further in the public health assessment. It does not mean that the listed contaminant will cause adverse health effects from exposures. The following sections present the levels of contaminants found in soil and groundwater and compare them to the appropriate comparison values. This will identify the COCs that need to be evaluated further to determine if they present a public health threat to the residents who live near the PGA North site.
3.1.1 On-site Soil Contamination
The Unidynamics facility is completely fenced off to prevent public access. Prior to 1978, waste solvents were disposed of in four dry wells on the Unidynamics property. In 1989, during the remedial investigation at Unidynamics facility, 51 volatile organic compounds (VOCs) were found in the on-site soil, including trichloroethylene (TCE), methyl ethyl ketone (MEK), isopropanol, trichloroacetic acid (TCA), toluene, and acetone. Table 1 lists the 1989 soil contaminants and their comparisons to nonresidential SRLs (Crane 1989).
Table 1: On-site Soil VOC* Contaminants Concentrations and Comparison to SRLs†.
|
Chemical |
Range (ppm ‡) | Occupational SRL (ppm) | Above SRL? |
| TCE § | <1.0 - 5,586 | 70 | YES |
| MEK ¶ | <1.0 - 179 | 27,000 | NO |
| Isopropanol | <1.0 - 962 | 10,000 | NO |
| TCA ** | <1.0 - 42 | 4,500 | NO |
| Toluene | <0.5 - 6 | 70 | NO |
| Methanol | <1.0- 48 | 340,000 | NO |
| Acetone | <1.0 - 232 | 8,800 | NO |
TCE concentrations were below the respective nonresidential SRL until depths of approximately 34 feet deep with the highest TCE soil concentrations found at 39 - 50 foot depths. The highest TCE concentration in surface soil (0-2ft.) was 0.2 ppm. Concentrations of acetone, MEK, toluene, isopropanol, TCA, and methanol were below their respective SRLs. ADHS was unable to obtain more recent soil data. According to Malcolm Pirnie (consultant for Crane Co.), the levels of these chemicals have been reduced since remediation activities (air stripping, well injection) began in 1994. If surface runoff has occurred, it would not be a problem since the surface levels of TCE are below the SRL.
Chemical analyses for metals in samples from the dry wells and sedimentation tanks indicate that seven of the 11 metals that were analyzed were found above background concentrations. These included aluminum, barium, arsenic, mercury, lead, chromium and zinc (Dames & Moore 1988). These levels have also been reduced since the remediation activities began. The 1989 metals concentrations are provided below in Table 2.
Table 2: Highest 1989 On-site Soil Metals Concentrations and Comparison to SRLs*.
|
Metal |
Highest Concentrations (mg/kg †) | SRL (mg/kg) | Above SRL? |
| Aluminum | 80,000 | 1,000,000 | NO |
| Barium | 3,240 | 110,000 | NO |
| Arsenic | 110 | 10 | YES |
| Mercury | 4.0 | 180 | NO |
| Lead | 3,100 | 2,000 | YES |
| Chromium | 290 | 4,500 | NO |
| Zinc | 4,200 | 510,000 | NO |
As shown on Table.2, the 1989 concentrations of arsenic and lead were above the respective SRLs. Pesticides were found in concentrations that were representative of background concentrations in agricultural areas. ADHS does not have available data to determine the type or amount of radioactive materials that were used at the facility.
3.1.2 On-site Groundwater Contamination
As of February 1999, Subunit A had levels of TCE that range from less than 1.0 micrograms per liter (µg/L) to 4,500 µg/L with the highest concentrations on-site (Crane 1989). Perchlorate was found in Subunit A in an on-site monitoring well at 81 µg/L. The Subunit B/C has levels of TCE ranging from non-detect to 4 µg/L with the highest concentrations being on-site. Table 3 below shows the concentrations of TCE and perchlorate in the two subunits compared to MCLs (ADEQ 1999; Malcolm Pirnie 1999a).
Table 3: Current On-site TCE* and Perchlorate Concentrations in the Two Groundwater Subunits Compared to MCLs†.
|
Subunit |
Range of TCE Concentrations (µg/L‡) | Above TCE MCL? (5 µg/L) |
Range of Perchlorate Concentrations(µg/L) | Above Perchlorate HBGL§ (31.5 µg/L) |
| A | ND - 4500 | YES | NDe - 81 | YES |
| B/C | ND - 4 | NO | ND | NO |
The drinking water for the Goodyear municipal wells comes from Subunit C. The Goodyear Well #10 is the only municipal well in the groundwater plume area. TCE has never been detected in this well. As can be seen from Table 3, perchlorate has not been detected in Subunit B/C.
3.1.3 Past On-site Thermal Oxidizer Emissions
The thermal oxidizer was in operation intermittently from 1994 to 1998 during which time it was periodically tested for removal efficiency of the on-site soil contamination. The thermal oxidation system was turned off in October 1998 to evaluate the need for continued soil remediation at the Unidynamics facility.
According to the data provided by Malcolm Pirnie and CH2MHILL, the only chemical that was analyzed in the emissions since January 1996 was TCE. The levels of TCE detected in the emissions ranged from 0.25 µg/L to 59 µg/L during the years 1996 to 1998 (CH2MHILL 1999b). Although pilot testing was conducted in 1993, emissions data from June 1994 to December 1995 were not available. Tests for dioxin were not normally included in the monitoring tests that were conducted on the thermal oxidizer at the Unidynamics facility.
According to the National Research Council (NRC), the release of dioxins from a thermal oxidizer unit is dependent on several factors. These include the type of chemicals and chemical mixtures, the internal temperature of the unit while in operation, and whether the unit is equipped with a quencher. According to Therm Tech, the manufacturer for the thermal oxidizer at the Unidynamics facility, when their units are operated properly and have the correct pollution equipment, there is no release of dioxins (Therm Tech.1999). ADHS was unable to get data to verify this statement.
As stated in the NRC report on Waste Incineration and Public Health, all types of organic chemicals, including polychlorinated dioxin/furans, can be destroyed under high-temperature oxidizing conditions. Destruction can occur at around 1800 o Fahrenheit (ºF) or higher if oxygen and organic molecules are well mixed as in practical combustion devices. Destruction of polychlorinated dioxins/furans present in the waste feed stream can take place at temperatures as low as 1350 o F if oxygen and organic molecules are perfectly mixed. However, dioxins and furans are also produced within the incineration process from precursors that are not destroyed below 1,800 o F. Although dioxins/furans may be present in the incoming mixture, most of the dioxins/furans in the exhaust gases are the products of formation within the incinerator and not persistence of the compounds present in the waste stream (NRC1999, p.3-19). According to Malcolm Pirnie, the internal temperature of the thermal oxidizer when in operation was around 1,600 ºF (Malcolm Pirnie 1999b).
Without proper emissions data, the ADHS cannot determine if, or how much, dioxin was present in the emissions from the thermal oxidizer on the Unidynamics facility and whether the emissions presented a public health hazard to community residents in the past.
There is also an air stripper at the facility which is used to remediate the contaminated groundwater. The TCE is routed through granular activated carbon and adsorbs to the carbon. The carbon must be changed out periodically in order for the system to effectively remove the TCE before it is released into the outside air. Thus, proper operation of the air stripper and carbon vessels is very important. If improperly operated, it could result in a release of TCE to the air. ADHS does not have available data to evaluate whether this unit has been or is currently being correctly operated.
The off-site contamination consists of a groundwater plume that extends from the Unidynamics facility northward for approximately 2 miles.
3.2.1 Off-Site Groundwater Contamination
Globe and SunCor Private Wells
There are seven private irrigation wells and one private domestic well located on the northern portion of the groundwater plume. Three of these wells are known as the Globe Wells #1, #2, and #4 and are located west of Bullard Road. The other 4 wells, known as the SunCor wells, are located east of Bullard Road.
Globe Well #1, which is located behind the house on Bullard Road, and Globe Well #2, located further west from Globe Well #1, provide irrigation water to the small irrigation canals that parallel the RID on the south side to the west of Bullard Road. Globe Well #4 is located in the middle of the fields. SunCor irrigation wells #33A, #33B, and #33C located on the northern end of the groundwater plume. SunCor Well #33A has a permanent activated carbon treatment system and is being incorporated in the final groundwater remedy. Water from this well is being used to irrigate the golf courses and decorative lakes in Pebble Creek and will be similarly used for the new SunCor housing development which is being built east of Bullard Road. SunCor Well #33B is used only for emergency purposes. SunCor Well #33C has been abandoned.
The MCL for TCE is 5 µg/L. Since perchlorate does not yet have an MCL, it is compared to ADHS's interim screening level known as the health-based guidance level (HBGL) for perchlorate of 14 µg/L. The Globe Well #1 and #2 have levels of TCE above the MCL. SunCor Well #33A has elevated levels of TCE but this is corrected with the use of a carbon filter system. All the wells that were tested for perchlorate had levels below the HBGL. Tables A1 - A10 in the Appendix summarize the sampling data of these wells from 1997 to 1999 (Malcolm Pirnie 1999a).
The irrigation water from the Globe wells flows into a holding pond located nearby between the RID and the small canals. According to the ADEQ, the holding pond which is owned by the Globe Corporation, has never been tested for contaminants. The irrigation water is cycled through the fields and held in the holding pond until further need arises. It is safe to assume that the water in the holding pond has traces of TCE and perchlorate as does the irrigation water in the small canals since they are connected. Table 4 provides a summary of the TCE and perchlorate levels found in the Globe and SunCor wells and comparisons to the appropriate screening levels (Malcolm Pirnie 1999a; ADEQ 1999).
Table 4: TCE* and Perchlorate Concentrations in Private Irrigation/Domestic Wells (February 1997 - February 1999).
| Well | TCE | Perchlorate | Comments | |||
| Range µg/L‡ (before filter) | Filter system? | Above MCL§ of 5 µg/L? | Range (µg/L) | Above HBGL¶ of 31.5 µg/L? |
||
| Globe #1 | 39 | NO | YES | ND** | NO | Used for irrigation 20 days/month. |
| Globe #2 | ND - 25 | NO | YES | 5 | NO | Used to irrigate fields west of Bullard Road. |
| Globe #4 | ND - 1 | NO | NO | NS†† | NS | Is minimally used for irrigation. |
| Globe Domestic | 19 - 250 | YES | < 1.0 (after filter) |
ND | NO | Used as drinking water. |
| SunCor 28A |
ND-<1 | NO | NO | NS | NS | --- |
| SunCor 29A |
ND-< 1 | NO | NO | NS | NS | --- |
| SunCor 33B |
ND-< 1 | NO | NO | NS | NS | Rarely used. |
| SunCor 33A |
340 - 490 | YES | ND (after filter) |
NS | NS | Used for golf course and decorative lakes in Pebble Creek and the new SunCor developments. |
|
SunCor |
ND- 270 | NA‡‡ | NA | 6 | NO | Abandoned. |
Results shown in Table 4 indicate that the treatment system on the Globe Domestic private well and the SunCor Well #33A continues to be effective in decreasing the TCE concentrations to <1 µg/L which is below the MCL of 5 µg/L. Photographs of the Globe and SunCor wells, the connecting canals, and holding pond are located in the Appendix.
Park Shadows Apartments Private Wells
Park Shadows Apartments are located on Litchfield Road approximately one-half mile south of the Unidynamics plant encompasses 44 square acres. There is a drinking well and an irrigation well located on the grounds. The drinking well, which draws water from the Subunit B/C aquifer which is clean, has been regularly sampled over the past several years and has never had any detection of TCE. The irrigation well is screened at a higher level and pulls water from Subunit A. According to the ADEQ, TCE concentrations in the irrigation well have been detected at 2.2 µg/L twice over the past 10 years. However, in March 2000, TCE was detected at a level of 23 µg/L in the irrigation well. ADEQ has strongly advised the Park Shadows Apartments management not to change the irrigation well into a drinking water well. Table 5 provides the concentrations of TCE in the wells at the Park Shadows Apartments.
Table 5: TCE* Concentrations in Private Wells at Park Shadows Apartments
| Wells | TCE (µg/L†) | Above MCL‡? | Perchlorate |
| Irrigation Well | ND§ - 23 | YES | NS¶ |
| Drinking Water Well | ND | NO | NS |
As can be seen from Table 5, TCE has been detected in the irrigation well at the Park Shadows Apartments at levels above the federal MCL. The private wells at Park Shadows have not been tested for perchlorate.
In this section, TCE was identified as a COC in on-site soil. Both TCE and perchlorate were identified as COCs in on-site groundwater. TCE was identified as COC in off-site groundwater. These COCs will be further evaluated based upon a toxicological evaluation in order to determine if they present a public health threat.
In order to determine if residents are being exposed to the chemicals at levels of public health concern at the site, pathways are identified to determine if and how residents are being exposed to the contaminants. A resident can only be exposed if a pathway is completed at levels of public health concern. Pathway analysis considers the source of contamination, the transport of the contaminant through environmental media, an exposure point, a potential route of exposure, and the existence of a receptor population. Both current and future potential pathways are evaluated.
4.1 Incomplete Exposure Pathways
Incomplete current exposure pathways indicate that the contamination is present but is not able to reach the surrounding population for a variety of reasons.
On-site Soil and Groundwater Contamination
The Unidynamics property is fenced off preventing any public access to the site and exposures to the soil and groundwater contamination. Unidynamics used to dump some of their waste in an area near the mountains just west of the facility known as White Tanks. The investigation of the contamination at White Tanks is still being conducted.
The thermal oxidation system was turned off in October 1998 to evaluate the need for continued soil remediation at the Unidynamics facility. Currently, no one in the Goodyear area is being exposed to the emissions from the thermal oxidizer.
Future exposures to thermal oxidizer emissions will not occur unless the thermal oxidizer is put back into operation. USEPA is in the process of deciding if the thermal oxidizer is needed for further on-site soil remediation. If the thermal oxidizer is put back into operation, ADHS will request to review and evaluate the proposed sampling plan for testing air emissions to ensure it is protective of public health. In addition if the thermal oxidizer is used again, ADHS will request the air emissions data to evaluate and determine if a public health threat exists.
SunCor Well # 33A, which has a carbon filter treatment system, is currently being used to provide water for the ornamental lakes and golf course in the Pebble Creek housing development. Use of the treated water does not represent a health hazard if the carbon treatment system is functioning properly.
4.2 Complete Past, Current, and Future Exposure Pathways
Past Occupational Exposure Pathways
It is known from our preliminary overview that many former Unidynamics workers were exposed to TCE and other chemicals in their jobs on a daily basis. These would have included inhalation, ingestion, and dermal exposures to the various chemicals used at the plant. Their reports indicated that they were exposed to many different chemicals including nitric acid, tear gas, MEK, hydrochloric acid, explosive chemicals, radioactive materials such as tritium and cobalt, and TCE while performing different types of jobs.
Past Air Emissions Exposure Pathways
Past thermal oxidizer emissions could have led to inhalation exposures for residents living nearby the unit. Because many community residents are concerned about their past inhalation exposures to the thermal oxidizer emissions, ADHS has calculated past inhalation exposure doses from the available emissions data. These are presented in Section 5.1.1.1.
Current and Future Exposure Pathways
It is possible that dermal, inhalation, and ingestion exposures have occurred and will continue when farmworkers irrigate the fields, and when children play in the irrigation water in the small canals or at the Park Shadows Apartments. Additional exposures may also occur if the abandoned wells in the area are fixed and used for drinking or irrigation purposes, or if an irrigation well is converted into a drinking water well. Photographs of the Globe wells, small irrigation canals, and nearby irrigation water holding pond are provided in the Appendix.
Approximately 2,000 homes have been built in the Pebble Creek housing development, of which 1,500 are currently sold. It is anticipated that approximately 6,000 residents will soon be living in this area assuming three residents per house. The new SunCor housing development that is currently under construction will have approximately 3,500 homes and 10,500 residents. Construction for the new Globe housing development, which will be located just west of Bullard Road and south of the Roosevelt Irrigation District (RID) canal, has not yet begun but approximately 2,000 homes are planned bringing in approximately 6,000 new residents into the area. The Globe Corporation, who owns the land west of Bullard Road, stated that the Globe wells may be shut down when housing construction begins since they won't be needed for irrigation purposes.
Table 6 provides a description of the past, current and potential future exposure pathways that have been identified and the estimated surrounding population at risk. These estimates assume three persons per residence.
Table 6: Summary of Exposure Pathways.
|
Source |
EXPOSURE PATHWAY ELEMENTS | Time | ||||
| Media | Point of Exposure | Route of Exposure | Estimated Population† | COC ‡ | ||
| Unidy-namics | air soil groundwater |
air emissions soils groundwater |
ingestion inhalation dermal |
300 | TCE§ | past |
| Thermal Oxidizer | air | air emissions | inhalation | 400 | TCE | past |
| Park Shadows Apts. | groundwater | water used for irrigation purposes | ingestion dermal inhalation |
600 | TCE | past current future |
| Globe #2 Well | groundwater | water in irrigation canals | ingestion dermal inhalation |
10 farmworkers | TCE perchlorate |
past current future |
| Globe #2 Well & SunCor #33A |
groundwater | irrigation water for canals, golf courses, & ornamental lakes |
ingestion |
Pebble Creek 4,500 res.¶ (2,000 homes) |
TCE perchlorate |
past current |
| Globe #2 Well & SunCor #33A |
groundwater | irrigation water for canals, golf courses, & ornamental lakes | ingestion dermal inhalation |
Pebble Creek 4,500 res. (2,000 homes) SunCor 10,500 res. (3,500 homes) Globe 6,000 res. (2,000homes) |
TCE perchlorate |
future |
5.0 PUBLIC HEALTH IMPLICATIONS
The potential for adverse health effects in persons exposed to site-specific contaminants through current or future exposure pathways has been analyzed by ADHS. Some children could be exposed to TCE and perchlorate if they play or drink the water in the small irrigation canals or in the holding pond located next to the larger RID canal. Two of the Globe irrigation wells have concentrations of TCE at levels which are above USEPA's MCL. TCE was also recently detected in the irrigation well at the Park Shadows Apartments at a level which is above the federal MCL. Concentrations of perchlorate were found in Globe Well #2 irrigation well but the level was not above the health-based guideline value. Based on these facts, TCE is the only contaminant of concern which merits detailed evaluation.
5.1.1 Health-Based Guidance Levels (HBGLs)
Health-Based Guidance Levels (HBGLs) are tools used to assist in evaluating the public health risk posed by each specific contaminant of potential concern. They are calculated by ADHS using a human health-based approach that is generally consistent with risk assessment methodologies recommended by ATSDR and USEPA. ADHS has used standard exposure assumptions, and, where necessary, has made conservative assumptions based upon research of the particular exposure scenario and professional judgement. Equations used to quantify exposures were based upon generally accepted methods, models, toxicity values, and assumptions developed by USEPA. The standard exposure assumptions were obtained primarily from Risk Assessment Guidance for Superfund (RAGS), Supplemental Guidance Standard Default Exposure Factors (USEPA 1991). The risk management values used to calculate the HBGLs are consistent with the methodology used to calculate the Arizona residential Soil Remediation Levels (SRLs). HBGLs protect against noncancer health effects, and limit excess lifetime cancer risk to one-in-one million (10-6) for known human carcinogens and to one-in-one-hundred-thousand (10-5) for possible and probable human carcinogens.
Health-Based Guidance Levels (HBGLs) are individually protective of human health, including sensitive groups, over a lifetime. Chemical concentrations that exceed the applicable HBGL may not necessarily represent a health threat. Rather, when contaminant concentrations exceed the HBGL, further evaluation may be necessary to determine the potential public health risk. The HBGLs calculated in this public health assessment consider the human health threat from the cumulative inhalation, ingestion and dermal contact with TCE in the small irrigation canals. They were also calculated for inhalation contact with TCE in the emissions that came from the thermal oxidizer.
5.1.1.1 Health-Based Guidance Levels (HBGLs) for Past On-site Thermal Oxidizer Emissions
The ADHS calculated an annual ambient air HBGL for TCE levels that were detected in the emissions of the thermal oxidizer during the time it was in operation to determine if residents were exposed to levels of TCE that could affect their health. The highest TCE level detected was used in the calculations, which assumed that people were consistently exposed to that level for 30 years, 350 days per year. The exposure duration for carcinogens was assumed to be 30 years, with six of those years as a child and 24 years as an adult. Since exposure to contaminants in air may be different for children and adults, carcinogenic risks during the first 30 years of life were calculated using age-adjusted exposure factors. These factors integrate exposure from birth until age 30, combining contact rates, body weights, and exposure durations for small children and adults. Exposure doses were averaged over a lifetime (70 years) for carcinogens.
Annual HBGLs are also specifically protective of noncancer health effects for childhood exposure. Exposure assumptions reflect childhood inhalation rates and body weight. The focus on children is protective of the higher daily intake rates by children relative to their body weight. For noncancer health effects, the exposure duration was assumed to be 350 days per year for six years. Exposure doses are averaged over the period of exposure (six years) for noncancer health effects. Air HBGLs use the default childhood inhalation rate of 10 cubic meters per day (m3/day) and default body weight of 15 kilograms (kg) (USEPA 1989,1991).
The ADHS used a "box model" to calculate the movement of the emissions from the stack of the on-site thermal oxidizer into the residential areas of Goodyear (ADHS 1997). It assumes the air is well-mixed within the box and the dimensions of the box are equal to the human breathing zone height and the length of the emission source in the predominant wind direction. Given these assumptions, ADHS estimated outdoor ambient air TCE concentrations of 0.0016 mg/m3 due to the past vapor emissions from the thermal oxidizer on the Unidynamics facility.
Table 7 displays the estimated outdoor TCE air concentration using the highest TCE concentration detected in the available thermal oxidizer emissions data. This outdoor air concentration was then compared to the HBGL to determine if the TCE in the emissions presented a health threat when the thermal oxidizer was in operation.
Table 7: Estimated Outdoor Air Concentrations of TCE* in the Thermal Oxidizer Emissions and Comparison to the HBGL† (1996 through 1998).
|
Range of Emission TCE Concentrations |
Estimated Outdoor Air TCE Concentration in Emissions | Ambient Air HBGL for TCE | Above HBGL? |
| 0.25 - 59.0 µg/L‡ | 0.0016 mg/m3 § | 0.009 mg/m3 | NO |
As can be seen in this table, the concentrations of TCE in the past emissions from the on-site thermal oxidizer did not exceed the HBGL. This indicates that the level of TCE in the emissions would not be considered a health threat to the community even if the thermal oxidizer operated for 30 years. But this is not applicable to dioxin emissions since it they were not tested for during the time the thermal oxidizer was in operation.
5.1.1.2 Health-Based Guidance Levels (HBGLs) for the Contaminated Water in the Small Irrigation Canals
This section analyzes all the various exposure pathways that children, adults, and farmworkers may be exposed to the contaminated water in the small irrigation canals. ATSDR and ADHS standard exposure assumptions for intake rates, body weights, exposed dermal surface area, averaging times, and exposure duration were used. Equations and exposure factors are provided in Table A11-A29 in the Appendix. ADHS calculated both residential and occupational HBGLs as comparison values that would incorporate all the various exposure pathways to the contaminated water via incidental ingestion and dermal contact, and inhalation pathways.
The residential exposure scenario conservatively assumes that adults and children are exposed to the contaminated irrigation water via inhalation, ingestion, and dermal contact during periodic flood irrigation times or play activities such as playing in the canal water. A child is assumed to play in the irrigation water for 4 hours per day, 350 days per year (City of Phoenix 1998) for six years. The child is exposed via incidental ingestion and dermal contact with the contaminants in the water for a 4-hour period during each irrigation event (ADHS 1997a). An adult is assumed to have incidental contact with the irrigation water that has flooded the fields while walking next to the irrigated fields. It is assumed that the amount of time for this activity would account for one hour per day, 350 days per year for 30 years. The adult is exposed via inhalation of contaminants escaping from the flood irrigation waters for the 4 hours that the water is assumed to be standing in the property.
The occupational exposure scenario for flood irrigation quantifies exposures to workers involved in maintenance of the irrigated properties. This exposure scenario conservatively assumes that workers are exposed to contaminants in the flood irrigation water via incidental inhalation, ingestion and dermal contact during regular farming activities. A farmworker involved in flood irrigation duties is assumed to have incidental inhalation, ingestion, and dermal contact with the flood irrigation water for eight hours per day, 250 days per year for 25 years (ADHS 1997).
ADHS's HBGLs for flood irrigation indicated the highest concentration of TCE in the contaminated groundwater that would not be considered to cause adverse health effects when used for irrigation purposes in the fields. The residential HBGL for TCE is 397 µg/L for adults and 87 µg/L for children. The occupational HBGL is 100 µg/L for adults. As seen in Table 8 below, estimated exposure doses from ingestion of contaminated water from the Globe #2 well and the Park Shadows irrigation well are below the respective HBGL.
Table 8: Comparison of TCE* Concentrations in the Globe Irrigations Wells to the HBGLs† .
| Chemical Found in Private Well | Exposure Pathway | Usage of Private Well | Comparison of Exposure Intake to HBGL | ||
| TCE Levels in Wells | HBGL | Exceeds HBGL? | |||
| TCE | Globe #1 Globe #2 Irrigation Wells |
irrigation of fields | 39 µg/L‡ 22 µg/L |
adult: 397 µg/L
child: 87 µg/L occupational: 100 µg/L |
NO |
| TCE | Park Shadows Irrigation Wells | irrigation of apartment grounds | 23 µg/L | NO | |
ADHS concludes that the TCE levels detected in irrigations wells Globe #1, #2, and Park Shadows do not represent a current public health threat.
5.1.1.3 Ingestion Exposures to Eating Edible Plants Irrigated with Contaminated Groundwater
In response to community concern, the ADHS conducted research to determine if a public health threat exists from the consumption of vegetables that could be grown in the fields that have been irrigated with the TCE contaminated groundwater. A literature search was conducted to identify how volatile organic compounds (VOCs) are taken up by edible plants and what the accessability of the VOCs are to humans who might eat the plants. ADHS has concluded that there are insufficient data to identify the possible health threat related to the ingestion of edible plants grown with the use of contaminated groundwater.
While much of the present research has focused on the uptake of pesticides into plants, the research on the uptake of industrial pollutants by plants and food crops is rudimentary. Studies have focused on the uptake of individual organic chemicals by crops such as corn, radishes, barley, beets, wheat, and soy. However, experimental results have been inconsistent, and have been dependent on the various factors within the study.
Trapp and McFarlane (1995) have developed mathematical models to account for some of these variables in order to predict the uptake of organic chemicals into plants and the fate of different chemicals. However, the authors suggest that more data are needed for a variety of chemicals and tissues to strengthen the correlations. Consistent correlations would enable investigators to predict how much of a chemical is absorbed into the plant and its accessability to humans.
Available data suggest that the uptake of organic contaminants by plants is dependent on the various properties of the chemical, the plant, and its environment. Until these variables can be determined and identified, any health threat to humans due to the consumption of food grown with TCE contaminated groundwater cannot be determined.
5.1.2 Limitations of Toxicological Data
More detailed toxicological information on TCE and perhclorate are summarized in the Appendix for reference. Each chemical is summarized with regard to use, interaction with other chemicals, exposure routes, toxicokinetics, toxic (health) effects, carcinogenicity and regulatory status. Much of this information is provided by the Toxicological Profiles published by the ATSDR. ADHS recognizes that the scientific literature includes limitations, such as the extrapolation of high-dose animal studies to low-dose human exposures and studies done on single chemicals while many exposures may be to complex mixtures of chemicals. ADHS has considered these factors in the evaluation of the PGA- North site.
5.2 Health Outcome Data Evaluation
5.2.1 Evaluation of Arizona Department of Health Services (ADHS) Health Studies
The ADHS studies reviewed in the Health Outcome Data Section 1.5, analyzed cancer and childhood leukemia mortality and incidence rates in Maricopa County, including the Goodyear area, since 1965. These studies measured the mortality of five disease categories and the incidence of childhood cancers and leukemia. These studies did not measure morbidity (illness) or any adverse health effects that do not result in death or cancer. There was no indication of elevated mortality or incidence rates of total cancers or childhood leukemia in the Goodyear area found in these studies.
If higher cancer rates had been found in the Goodyear area, no causal relationship could be drawn from these findings. Since the development of cancer has multiple risk factors and potential causes (e.g., lifestyle, genetics, socioeconomic status, and environmental), it is not possible to assume that a given disease condition is or is not caused by a specific environmental contaminant. In addition, past exposures cannot be quantified or verified eliminating the possibility of determining causation in any health study that would be conducted. Therefore, if an additional study were conducted, it would not be able to determine if any cancers in residents in the Goodyear area are due to past exposures to TCE or any other contaminants from the PGA North site.
5.2.2 SunCor Housing Development Risk Assessment (1998)
In 1998, a risk assessment was conducted by Papadopulos & Associates, for the new SunCor housing development. It evaluated the human risk that residents might have from exposure to potential volatilization of TCE from contaminated groundwater beneath the SunCor housing development in Goodyear, Arizona. The ADHS reviewed the risk evaluation to determine if the assumptions and calculations used in the report were correct.
The potential migration of TCE from the groundwater through the overlying soil area and into the air was evaluated to determine the potential TCE concentrations in air that residents might breathe. The risk assessment concluded that TCE in the groundwater does not represent a significant risk from volatilization through soil to residents who live in the SunCorp development. There are limitations to modeling indoor air concentrations. ADHS cannot determine the accuracy of the modeling results without having access to the necessary data.
5.3 Health Concerns Evaluation
This section reviews the results of the ADHS survey, and addresses the concerns that were voiced by the community residents and former Unidynamics workers.
This survey process has been extremely successful in helping the ADHS identify and address many of the concerns of the community residents and former Unidynamics workers. Residents had many misunderstandings, worries, and concerns related to living near the PGA North site. ADHS helped to clarify many of these misunderstandings, alleviate some of the community fears, and address major concerns on a one-to-one basis with community members. In addition, ADHS sent environmental health educational materials to survey participants and doctors in the area.
The community survey is meant only to be used as guidance in identifying and addressing public health and community concerns. It is not designed to be a scientific epidemiological study. Since the results are not medically confirmed (with a few exceptions), the survey data cannot and should not be used to make conclusive statements concerning the health of the residents who live near PGA North site or who worked at the Unidynamics plant.
They are deeply concerned that many of their health problems are due to living near the PGA North site and being exposed to the contamination. Since some of the health conditions that were reported, such as eye and respiratory problems, are not legally required to be reported to a registry, there is no available health outcome database to use for comparison. This makes it extremely difficult to determine if any amount of a specific illness in an area is unusual. Therefore, no conclusions can be made as to whether the community residents are experiencing unusual adverse health effects (other than those that result in death) that would be related to exposure to the chemical contamination at the PGA North site.
Former Unidynamics workers have voiced major concerns about their health problems that have developed subsequently to their employment at the plant. Some of the health problems expressed by former workers (respiratory, heart, nerve, and eye problems) are consistent with long term exposure to working with high levels of TCE. However, ADHS is unable to link the cause for these health problems directly to past exposures to chemicals at the plant since there are many confounding factors. Because the development of cancer and other diseases have multiple risk factors and potential causes (e.g., lifestyle, genetics, socioeconomic status, and environmental), it is usually not possible to assume that a given disease condition is or is not caused by exposures to specific environmental contaminants. Past exposures of former workers at the Unidynamics plant cannot be quantified or verified. This eliminates the possibility of determining causation of subsequent diseases that former workers developed.
5.3.1 Community Residents Concerns
This section identifies and addresses the concerns of the community residents who were not former Unidynamics workers.
TCE is a clear, odorless, nonflammable liquid used for vapor degreasing of fabricated metal parts. Consumer products that contain TCE include typewriter correction fluid, paint removers and strippers, cosmetics, rug cleaners and spot removers, and adhesives. Before 1977, TCE was used as a general anesthetic, analgesic, grain fumigant, disinfectant, pet food additive, and extractant of spices and caffeine in coffee (ATSDR 1997).
5.3.1.1 Community Drinking Water Concerns
Yes. The drinking water in Goodyear, Litchfield, and Pebble Creek is safe to drink. The quality of drinking water supplied in these areas meets drinking water standards established by USEPA in the Safe Drinking Water Act amended in 1991. The municipal wells in the City of Goodyear, Litchfield Park Service Company, and Pebble Creek are monitored on a quarterly basis and there have been no detections of contaminants above drinking water standards. These standards are protective of public health. More specifically, the City of Goodyear routinely monitors wells in proximity to the TCE plume at least quarterly to ensure that the water is safe for consumption. The ADHS reviewed the past data from the samples taken from Goodyear wells #2, #3, and #10. The results show that these wells have no VOCs, including TCE at levels of public health concern. Since Goodyear well #10 is the only Goodyear municipal well that is located over the plume, it is being watched carefully to ensure that it is not contaminated.
The Crane Co. maintains 24 groundwater monitoring wells throughout the contaminated groundwater area under the direction of ADEQ. The purposes of the monitoring program are to define the horizontal and vertical extent of contamination, and to provide data on the effectiveness of the groundwater containment and cleanup program. This also helps to identify any municipal wells that may be in the path of migrating contaminated groundwater (USEPA 1999).
Groundwater is water found in large amounts under the ground surface. There are three main bodies of groundwater underneath the PGA North site that are called aquifers. Located at different depths, they are known as the upper Subunit A, middle Subunit B, and the lower Subunit C aquifers. The upper aquifer (Subunit A) contains groundwater that became contaminated from waste solvents that were disposed of in dry wells on the Unidynamics facility and is not used as a source for drinking water by the City of Goodyear. The middle aquifer (Subunit B) produces very little water and restricts groundwater from moving from the upper Subunit A to the lower Subunit C aquifer. The lower aquifer (Subunit C) is used for drinking water, agricultural and industrial purposes in the Goodyear area (USEPA 1999). The middle and lower Subunits B and C are often called the lower B/C Subunit aquifer.
TCE has been detected in a small area in the lower B/C Subunit aquifer. This contamination has not migrated to the Goodyear municipal wells. The Goodyear municipal well #10 is the only well that is located in the plume area. TCE has never been detected in this well. This situation is being monitored carefully by various agencies to prevent the municipal wells from becoming contaminated. Remediation activities are pulling the contamination away from the municipal wells so they will not become contaminated. Community residents are encouraged to call the ADHS and ADEQ for updates on this situation if they are concerned.
There are two private wells at Park Shadows Apartments. One is used for irrigation purposes and the other for drinking and domestic purposes. These wells are sampled on a regular basis as determined by ADEQ. Results from past samples have found that the drinking well had no detected VOCs, including TCE. Water samples from the irrigation well have detected levels of TCE at 2.2 micrograms per liter (µg/L) consistently for the past several years. Recent samples from this irrigation well have shown levels of TCE at 23 µg/L. This is above the USEPA's MCL of 5 µg/L but below the HBGL for irrigation water. This is not considered a health hazard. The drinking water well pulls water from Aquifer C which remains free of TCE. These wells have not been tested for perchlorate. It is recommended in this report that perchlorate be tested in these wells.
The water from the Globe wells, where the signs are posted, is contaminated with low detections of TCE and perchlorate. The water from these wells flows into the small irrigation canals that are used to irrigate the agricultural fields and is stored in the nearby holding pond. Because a new SunCor housing development is being built nearby which will bring more children into the area, the ADHS conducted an exposure assessment to determine if the water presents a health hazard to children. The analysis showed that the levels of TCE and perchlorate are not high enough to cause health problems even if children play in the canals every day of the year. The well water is being routinely monitored by ADEQ. Even though TCE and perchlorate are present in the small canals, it won't hurt anybody who comes in contact with the water or drinks it.
However, there are several physical hazards apparent around the canal area. There are rusty broken pipes around the various pumps in the area that are accessible to children. There are large open cement drains that children can crawl into and an open well that a child could fall into. This is also a concern since new residential areas are being built nearby. Photographs of these areas are included in the Appendix.
It is likely that farm workers could be exposed to the contaminated water in the small irrigation canals when working in the fields. This would happen if they drank the water, used the water to cool themselves, or used it to wash their hands and face. The ADHS conducted an exposure assessment to determine if the water presents a health hazard to farm workers. Although the water is contaminated, the levels of TCE and perchlorate are not high enough to cause health problems, even if the farm workers come in contact with it eight hours a day for 250 days per year. The water is being monitored by ADEQ. The remediation activities that are taking place will eventually clean the groundwater and the water in the canals. Even though TCE and perchlorate are present in the small irrigation canal water, the levels will not cause adverse health effects to anyone who comes in contact with or drinks the water.
Yes. Full scale remediation (cleanup) of the groundwater contamination began on the PGA North site in September 1990. The Crane Co. established groundwater monitoring, groundwater cleanup, and soil cleanup programs to implement the required cleanup. Groundwater cleanup is being accomplished through a network of groundwater extraction and groundwater injection wells. Six groundwater extraction wells pump approximately 1,300 gallons per minute to contain and restore the contaminated aquifer.
The extracted groundwater is treated to remove the VOCs. Then it is either re-injected back into the aquifer or used for irrigation. The groundwater treatment unit removes the VOCs using air stripping technology and then treats the contaminated air coming from the unit with granular activated carbon. There has been a drastic reduction of TCE concentrations since treatment began. The extraction wells have removed approximately 26,000 pounds of VOCs from the groundwater since operation of the system began. It is estimated that the system at the Unidynamics plant will operate for at least 25 years.
ADHS has routinely conducted several studies to analyze the amount and types of cancer during the past three decades throughout Maricopa County. These studies also include the Goodyear area. Results from these studies show that the Goodyear area did not experience elevated mortality or incidence rates of cancer, or childhood leukemia during the years from 1965 to1990.
According to the American Cancer Society (ACS), there are many causes of cancer. These include genetic factors, viruses such as the Epstein Barr virus which can cause various lymphomas, and the human papillomavirus (HPV) that can cause non-melanoma skin cancer, and environmental factors (ACS 1999). The ACS has available information on the different types of cancer, their causes, and treatment. Currently, no evidence suggests that the TCE in the groundwater has resulted in higher rates of cancer in the Goodyear area residents.
VOCs do not significantly collect in the human body. This class of chemicals is easily processed by the body and eliminated. Therefore, exposure in Goodyear to water contaminated with TCE or other VOCs should not result in collection of VOCs in people.
How much is collected in the body depends on the chemical properties of the contaminants. One of the main factors responsible for chemicals collecting in the body is when a chemical does not break down easily in the body. Because TCE is easily broken down by the body and excreted, it is unlikely that TCE would accumulate in the body tissues of people living in the Goodyear area.
The drinking water in Goodyear, Litchfield, and Pebble Creek is safe to drink and clean of perchlorate. However, there are small amounts of perchlorate in the Globe well #2 which provides water to the irrigation canals west of Bullard Road. It is not possible for the residents of Goodyear to come in contact with the perchlorate in the groundwater unless they drink, swim or rinse off in the irrigation water in the canals or holding pond. The perchlorate concentration in the irrigation canals is below the ADHS health guideline of 14 parts per billion (ppb). Nonetheless, the ADHS sent out health education information packages to doctors throughout the Goodyear area, to inform them of the perchlorate in the water, and the likelihood of any health effects from being exposed to the perchlorate.
Perchlorate originates as a contaminant in the environment from the solid salts of ammonium, potassium, or sodium perchlorate. The perchlorate part of the salts is quite soluble in water and can persist for many decades under typical groundwater and surface water conditions, because of its resistance to react with other available elements. Perchlorates dissolve easily in water and are quite capable of migrating to groundwater.
Perchlorates are used in pyrotechnics, explosives and jet or rocket fuels. They are also used as catalysts or as digesting agents in analytical chemistry laboratories, as etching and engraving agents, as an ingredient in electrolytic baths in depositing lead and electro-polishing and in the manufacture of various chemical compounds. Perchlorates can be used in oxygen-generating devices for life-support systems in submarines, space ships, bomb shelters and breathing apparatuses. Perchlorates can be used in paper and wooden matches and automobile air bags.
Potassium perchlorate is used to treat Grave's disease, an autoimmune disorder that affects the thyroid function leading to a hyperthyroid state. Perchlorate can interfere with the function of the thyroid. When this happens, the pituitary gland responds to the low level of hormones by producing thyroid-stimulating hormone (TSH) causing the thyroid gland to become enlarged. This can cause hypothyroidism where people can feel sluggish, depressed, cold, or tired. There are many causes for hypothyroidism. Thyroid disorders are very common, and are more frequent in females than in males.
USEPA is in the process of developing a federal standard for perchlorate that will be based on the research currently being conducted around the country. ADHS uses the health-based guidance level in the interim. As stated earlier, it is not possible for the residents of Goodyear to come in contact with the perchlorate in the groundwater unless they drink, swim or rinse off in the irrigation water in the canals or the holding pond.
5.3.1.2 Community Concerns Related to Air Pollution
The thermal oxidizer was in operation intermittently from 1994 to 1998. It was periodically tested for TCE removal efficiency of the on-site soil contamination. It was turned off in October 1998 to assess whether further soil remediation was needed. Presently, no one is being exposed to the emissions from the thermal oxidizer.
The dioxin emissions from a thermal oxidizer are dependent on the type of air pollution control equipment being used, the chemicals that are being burned, internal temperatures, and other operating conditions. Therm Tech, the manufacturer of the thermal oxidizer at the PGA North site, stated that this unit has all the necessary components to prevent dioxins from being formed. The unit has a quencher; it provides good mixing of the combustion gases enough to prevent dioxins from being created in the oxidizing chamber. ADHS was not able to get testing data on dioxin levels in emissions from other thermal oxidizers.
Chemicals in the emissions, including dioxins, from the thermal oxidizer will become diluted when they are released into ambient air. However without proper data, ADHS cannot determine if or how much dioxin was present in the past emissions from the thermal oxidizer at the PGA North site. The emissions data for the thermal oxidizer at the PGA North site includes only TCE since that is what was being removed from the soil. Past emission data and exposure dose analysis for TCE is provided in Section 5.1.1.
ATSDR reports that the average American adult has a circulating level of dioxin of seven picograms per gram (seven parts per trillion) of body fat (ATSDR 1998).It is estimated that the daily intake of dioxins and furans by a maximally exposed individual living near a modern thermal oxidizer is only 0.9%of the total daily intake and 99.1% is from other various sources, primarily meat and dairy products (ATSDR 1998, p.467).
Many Goodyear residents in the survey complained of respiratory problems. This included problems with asthma, hayfever, and other bronchial irritations. Many residents believe that their respiratory problems are due to the contamination on the PGA North site. However, due to the type and nature of the contaminants present at the PGA North site, it is extremely unlikely that they would cause these types of respiratory complaints reported by the community. There are several other environmental problems present in the Goodyear area that could cause these types of respiratory complaints. In fact, respiratory problems are found throughout the Phoenix Valley.
Residents also reported that a strange smell occurs in the area at night periodically. When this occurs, they and their children develop breathing difficulties which prevents them from going outside in the evenings. The nearby aluminum smelter, IMSAMET, was often identified as the source of the odors.
Many community residents are concerned about the emissions form the IMSAMET facility (formerly known as Imsalco). The aluminum recycling plant is located at 3829 South Estrella Parkway, near the southwest corner of Goodyear Airport. This facility is not part of the PGA Superfund Site, however, ADHS investigated these concerns.
IMSAMET of Arizona was first built to burn old airplane parts after WW II. It is now an aluminum smelter facility that recycles aluminum. Aluminum dross (impure aluminum) is brought to the site from both primary and secondary aluminum industries, and then crushed and milled to produce purified aluminum ingots. The ingots are then shipped out to industries such as auto makers, aluminum siding makers and roofing companies that use the recycled aluminum in their products. Four tons of recycled aluminum is shipped out every month to such industries.
The IMSAMET facility was investigated in 1989 in response to a series of complaints by local citizens about excessive emissions (white smoke and odors). As a result, the facility was issued 29 citations in 1989 by Maricopa County for operating in violation of County Visible Emissions Standards at night. During this investigation, "the white horizontal smoke plume appeared well over 1/4 mile from the source with no end in sight." Odors from the emissions produced were similar to a strong ammonia smell combined with a pungent onion odor (Maricopa County Memos 1990). IMSAMET installed a new baghouse to control the particulate emissions from the furnaces, and continued to educate their employees on proper operating procedures for the furnaces.
The type of industrial process conducted at IMSAMET will release smoke, odor, and particulates (small particles) into the air. According to Maricopa County, Level II source testing is conducted periodically by IMSAMET for criteria pollutants which include carbon monoxide (CO), nitrogen oxides (NOx), and particulate matter (small particles in the air). Since 1995, Level II source testing for criteria pollutants conducted by IMSAMET has indicated that the facility is in compliance according to the permit conditions listed by Maricopa County, with the exception of a test conducted in 1999. This test showed elevated levels of CO and the results are being verified. Maricopa County staff also visited the facility in response to the ADHS inquiry but stated that nothing could be identified as the cause of the odors. ADHS encouraged Maricopa County to continue its investigation especially at night.
Community residents continue to complain of intermittent white smoke at night which they believe causes their respiratory problems. Even though the levels of particulates in the emissions are within acceptable limits, the inhalation of particulates may cause respiratory irritation, aggravate mucous membranes, and create discomfort in those people already prone to respiratory disease (Maricopa County memos, 1990). Testing for specific substances such as lead, beryllium, cadmium, or dioxins have not been conducted. Community residents are encouraged to call the Maricopa County Environmental Response and Complaint line at 602/506-6616 if they would like to find out more about the IMSAMET facility, discuss their concerns, or find out more about its compliance history. IMSAMET will also offer tours of their facility for interested residents.
Additional air quality issues exist in the Goodyear area that could explain some of the respiratory problems that are affecting so many community residents. There are high levels of dust and particulate matter in the air that come from farming activities and pesticide spraying. These types of activities are known to cause respiratory problems but are oftentimes overlooked since much of the community focus is on the contamination at the PGA North site. The contamination at the PGA North site does not have the necessary environmental characteristics that normally cause such health problems throughout a surrounding community. This is described below in more detail.
Maricopa County has been in violation of the standards for small air particles (particulate matter less than 10 microns in size, called "PM-10") for most of the past decade. Particulate matter consists of airborne particles made of solid and liquid droplets of materials that vary in size and origin. The small particles can be inhaled into the respiratory tract causing respiratory problems. The smallest of these particles (less than 2.5 microns in size) are thought to be the most damaging since they can be breathed deeply into the lungs causing severe irritation.
The causal link between exposure to small particulate matter and adverse health effects is well established. While some people are not affected by this type of air pollution, others will be very sensitive and develop certain types of bronchial irritations including asthma, and hayfever. The estimated number of premature deaths due to PM-10 in Arizona is 963 per year. Those affected are primarily the elderly and those already suffering from a cardiopulmonary or respiratory disorders (ADHS, 1995). Particulate matter, including the smaller dust particles, can also carry certain allergens, or even viruses that may cause respiratory irritation.
According to the American Lung Association of Arizona (ALAA), respiratory problems are now extremely prevalent throughout Maricopa County. The growth of Phoenix has led to a tremendous amount of construction and farming activities which have increased particulates and dust in the air, pollens and molds, and other respiratory irritants throughout the Valley and the outlying areas (AALA 1999). Also, new pollens and molds have been introduced into the area as people have moved into the Phoenix Valley and planted different types of trees and shrubs.
Pesticides in the Goodyear Area
The Goodyear area is a large agricultural area with a climate that allows farmers to grow crops all year round which includes aerial spraying of pesticides throughout the year. There have been several reports by community residents that pesticide spraying occurs on the fields and also over cars driving on the roads. While many residents may not be reactive to this type of spraying, others may be very sensitive and develop certain health problems from being exposed to the aerial drift of pesticides. Residents who believe that they have experienced this type of exposure should contact medical doctors who are familiar with pesticide poisoning and discuss their individual situations.
Currently, community residents are not being exposed to chemicals on the PGA North site at levels that would be considered a public health hazard. The only possible exposures that residents may have to any chemicals related to the PGA North site is to the water in the small irrigation canals located on the north end of the groundwater plume, and typical exposure scenarios indicate this does not pose a public health hazard.
5.3.2 Former Unidynamics Workers Concerns
This section identifies and addresses the concerns that were expressed by many of the former Unidynamics workers.
As a defense contractor, Unidynamics was responsible for the design, development, production, testing, and support of tactical and strategic weapon and defense systems. A variety of chemicals such as nitric acid, hydrochloric acid, tear gas, explosive powders, paints, glue, oils, acetone, and other chemicals were used in this industry.
It is known from our preliminary overview that many former Unidynamics workers were exposed to TCE and other chemicals in their jobs on a daily basis. Their reports indicate that they were exposed to many different chemicals including nitric acid, tear gas, MEK, hydrochloric acid, explosive chemicals, radioactive materials such as tritium and cobalt, and TCE while performing different types of jobs. Many former Unidynamics workers reported that they were not adequately told of the dangers of the chemicals with which they were working and safety precautions were not always enforced.
During the survey, former employees described the type of work they did, and how they worked with the various chemicals. The workers responsible for cleaning metal parts did so by dipping them in large open vats of TCE with their bare hands up to their elbows on a daily basis. This would be an indication of direct dermal and inhalation exposures to TCE. Other employees packed hand grenades with powder, or tested tear gas components. The smoke from these tests would fill the building and everyone in the building would breathe the fumes. Reports indicated that employees continuously smelled fumes throughout the work day. Ventilation was not effective in getting rid of the chemical fumes from the daily chemical processes in the buildings. Employees stated that oftentimes these activities were conducted without proper protective equipment. While shoes, shop coats, and safety glasses were sometimes used, gloves or masks were not used regularly when working directly with the chemicals. These reports indicate that inhalation and dermal exposures occurred on a daily basis.
A separate building was used for making radioactive components for defense purposes. It is possible that employees were exposed to the radioactive materials. Without proper data, ADHS cannot determine the type of materials that were used or how they were handled.
Employees were responsible for the waste disposal of chemicals, including the radioactive waste, into dry wells located in the back of the facility. In 1980 and 1984, radioactive waste in the dumping area outside was cleaned up and taken to a proper radioactive waste facility. Chemical wastes were also taken to an area many miles west of Goodyear known as White Tanks where they were dumped, burned, and exploded. This aspect of the dumping is not covered in this report and can be addressed when additional data becomes available.
The employees that worked with the explosive powders described that they would go home covered in a pink chemical powder from the plant. This powder would then be spread in the carpet, clothes, towels, and curtains in their homes where their children would play with it. The powder would not wash out of their clothes, hair or skin. It would even get in the food in the kitchen. Although there was some concern about this voiced by the former workers, they stated that no one really understood the danger of children playing with the powder at that time and it was considered a normal occurrence. This situation would indicate direct dermal, inhalation, and possibly ingestion exposures to the pink powder, however ADHS does not know the chemical makeup of the powder.
A majority of the workers who called ADHS believed that their current health problems were caused from their past exposure to the chemicals used at Unidynamics. The major complaints reported by former workers included skin cancer, respiratory, heart, nerve, and eye problems. There were reports of various cancers such as male breast cancer, skin cancer and multiple melanoma, lung, throat and rectal cancers, leukemia, non-hodgkin's disease. Other health problems included vertigo, memory loss, facial swelling, skin problems, throat and esophagus problems, and headaches. It is very difficult to determine if these conditions are caused by previous exposures to the chemicals used at the Unidynamics plant since the exposures happened in the past and direct causation cannot be proven. While some of the symptoms that have been described by former employees are consistent with chemical exposures, there are many confounding factors that interfere with the determination of cause and effect in such a situation.
The use of radioactive materials at the former Unidynamics facility has been documented. However, ADHS was unable to obtain data to determine types of materials, and how they were used. This would help to determine what exposures to the radioactive materials may have occurred to the former workers. ADHS will conduct an investigation if future information becomes available on the type and amount of radioactive materials that were used at the facility.
It is beyond the scope of this general health assessment to conduct an epidemiological study of the health effects from past occupational exposures in this situation. However, since TCE is the chemical of concern that has been the focus of the remediation activities, the following paragraphs provide some description of health effects from occupational exposures to TCE. This will provide an indication of the types of health effects that have been suggested in studies conducted on chemical exposures to TCE in occupational settings.
A summary of animal and human studies that have been conducted on TCE can be found in the ATSDR Toxicological Profile for TCE (ATSDR 1997). The toxicological profiles are prepared in accordance with guidelines developed by the ATSDR and USEPA. They succinctly characterize the toxicologic and adverse health effects information for hazardous substances. Each peer-reviewed profile identifies and reviews the key literature that describes a hazardous substance's toxicologic properties.
Respiratory problems were the most noted Unidynamics worker health symptom. Although this type of health problem has many causes, it is possible that past exposures to chemicals used at Unidynamics may have caused respiratory problems for some of the former workers. In fact, one former worker stated that their doctor had requested that they change their job because the chemical exposures at work had compromised their esophagus and respiratory system. Morphology of lung cells has been studied in rats and mice exposed to TCE. A 30-minute inhalation exposure to 500 parts per million (ppm) resulted in changes in the nonciliated epithelial cess of the bronchial tree. Similar Clara cell-specific damage was observed in mice after a 6-hour exposure to 100 ppm TCE. A reduction in pulmonary enzyme activity was also observed. In an occupational study, a worker developed labored breathing and respiratory edema after welding stainless steel that had been washed in TCE. This was attributed to inhalation of the decomposition products of TCE. However, he also had a history of smoking which may have predisposed the subject to these respiratory effects (ATSDR 1997, p. 12).
Another common health complaint described by former workers were heart problems. Cardiac effects including tachycardia, ECG abnormalities, and arrhythmias have been reported in humans following acute inhalation exposures to TCE. A number of deaths following acute inhalation exposure to TCE have been attributed to cardiac effects (ATSDR 1997, p. 167). A few case studies of persons who died following acute occupational exposure to TCE have revealed cardiac arrhythmias to be the apparent cause of death. In animals, TCE is apparently responsible for the cardiac sensitization because chemicals that inhibit the metabolism of TCE increase its potency. In one study, hypertension, enlarged, heart, and arrhythmia were seen in some workers accidentally exposed to TCE at a level that was unspecified but at least 15 ppm. Sufficient human and animal information is available to identify the nervous system as the most sensitive target for the acute effects of TCE from inhalation.
Information from occupational studies on humans indicated that, while the nervous system may be the most sensitive target of TCE exposure, other targets include the liver and kidneys. Short term exposures showed that working with TCE and its breakdown products have led to residual neuropathy, characterized by nerve damage particularly characterized by facial numbness, jaw weakness, and facial discomfort (ATSDR 1997, p. 27). Other reported neurological effects of chronic occupational exposure to unquantified TCE levels include memory loss, mood swings, trigeminal neuropathy, cranial nerve VII damage and decreased psychomotor function, impaired acoustic-motor function, and psychotic behavior with impaired cognitive function. A case study of a retired metal degreaser who had been exposed to between 1.5 and 32 ppm for 1-2 hours per day over a period of 20 years reported symptoms of headache, forgetfulness, vertigo, nausea, and loss of feeling in hands and feet persisting for 4 years after retirement(ATSDR 1997, p. 38). Other symptoms of workers exposed to chronic long term exposures to TCE (between eight and 170 milligrams per cubic meter (mg/m3)) for one to two hours per day over a period of 20 years reported symptoms of headaches, forgetfulness, vertigo, nausea, and loss of feeling in hands and feet (ATSDR 1997, p. 171). Human experimental studies revealed mild effects on motor coordination, visual perception, and cognition (ATSDR 1997, p. 138). The symptoms noted above were reported by some of the former Unidynamics workers in the community survey.
A TCE registry has been established by ATSDR to monitor people in communities where exposure could be verified and doses could be adequately estimated. The participants are interviewed regularly to collect important health data over their lifetimes to provide more understanding of the effects of exposure to TCE. Thus far, data indicate excess numbers of heart disease and respiratory cancer deaths, as well as stroke, anemia, liver and kidney disease, and hearing and speech impairment. The greatest limitation to these studies is the difficulty in estimating dose, and possible exposure to multiple chemicals (ATSDR 1997, p.170).
The development of adverse health effects from exposure to TCE is "dose" and "situation" dependent. According to the ATSDR Toxicological Profile for TCE, a susceptible population will exhibit a different or enhanced response to TCE than will most persons exposed to the same level of TCE in the environment. Reasons may include genetic makeup, age, health and nutritional status, and exposure to other toxic substances such as cigarette smoke. These factors may result in a reduced detoxification or excretion of TCE, compromising the function of organs affected byTCE. In addition, people who consume alcohol or are treated with disulfiram may be at greater risk of TCE poisoning because ethanol can inhibit the metabolism of TCE and cause it to accumulate in the bloodstream, increasing its potential effects on the nervous system. Compromised hepatic and renal function may place one at higher risk upon exposures to TCE or its metabolites since the liver serves as the primary site of TCE metabolism and the kidney as the major excretory organ for TCE metabolites. Metabolism of TCE differs significantly between men and women (ATSDR 1997, p. 161).
Although many of the self-reported symptoms reported by workers appear to be consistent with TCE exposures, the cause for such symptoms cannot be fully determined by this health survey. An in-depth study would be required to determine if an association between past exposures to TCE and present health problems could be identified. Since the exposures occurred in the past, and since there are many factors that would interfere with the analysis, such a study would have many limitations preventing a solid conclusion. In other words, based on the available data, there is no way to determine if a worker's past exposure to the chemicals used at Unidynamics is the definite cause of their current health problems. Former workers, who are concerned about their exposures to the chemicals at the plant, are encouraged to speak with a doctor who is trained in occupational exposures and to discuss their health status and previous exposures to chemicals for a more specific individual exposure assessment.
A summary that provides a description of additional studies conducted on occupational exposures to TCE and their results is provided in the Appendix, and also in the 1997ATSDR Toxicological Profile for TCE.
According to the ATSDR Toxicological Profile for TCE, tumors in the lungs, liver, and testes were found in studies using high doses of TCE in rats and mice, providing evidence that high doses of TCE can cause cancer in experimental animals. Based on the limited data in humans regarding TCE exposure and cancer, and evidence that high doses of TCE can cause cancer in animals, the International Agency for Research on Cancer (IARC) has determined that TCE is probably carcinogenic to humans. In general, the associations drawn from the limited epidemiological data in humans, as well as cancer studies in animals, are suggestive yet inconclusive. Based on the available data, cancer should be an effect of concern for people exposed to TCE in the environment and at hazardous waste sites (ATSDR 1997, p.5, 153). In general, people with the greatest potential for exposure to TCE are those exposed in the workplace. Health effects from these exposures depend on many factors including sex, age, type and length of exposures to TCE, and concentrations of TCE.
Three European studies have found slight but statistically significant increases in cancer in workers exposed to TCE. One such study showed that the combined incidence of stomach, liver, prostate, and lymphohematopoeitic cancers was increased among 2,050 male and 1,924 female Finnish workers who were occupationally exposed primarily to TCE and other solvents. The workers were exposed principally through inhalation, although there was some dermal contact. In a study of Swedish workers who worked with TCE, a statistically significant increase in non-hodgkin's lymphoma was observed. However, these studies are limited by uncertainties in the exposure data, small sample sizes, and likely exposure to other chemicals (ATSDR 1997, p. 46, 96).
The ADHS survey showed that among the workers, skin cancer including melanoma was the most prevalent cancer. This was followed with cases of lung cancer, non-hodgkin's lymphoma, male breast cancer, and throat cancer. Other epidemiologic studies have examined the effect on workers from inhalation exposure to TCE. A significant increase in bladder cancer and lymphomas was detected in a cohort of 1,424 men with unspecified exposure to TCE. In another study, a significant rise was also discovered in the incidence of lung/bronchus/trachea, cervix, and skin cancers in more than 330 deceased cleaning and/or laundry workers who worked with TCE.
It is not known whether exposure to TCE can cause lupus. Systemic lupus erythematosus (SLE), commonly called lupus, is a chronic multisystem inflammatory disorder. The exact cause of lupus is unknown. In lupus, the body produces abnormal antibodies that react against the person's own tissues. Lupus can affect many organs of the body including the heart, lungs, kidneys, and central nervous system. The disease can look like many different illnesses; it may cause some rashes, arthritis, anemia, seizures, or psychiatric illness (American College 1992).
SLE is four times more common in African Americans compared with Caucasians in the United States. Hispanics and Asians have been reported to have higher rates than Caucasians. An elevated prevalence of SLE has been found in North American Indians. However, this increased prevalence was isolated to three of 75 American Indian tribes. A prevalence rate of 119 per 100,000 persons was reported in Sioux women (Fessel 1988).
According to the ATSDR Toxicological Profile for TCE, learning disabilities and mental retardation have not been associated with chronic exposure to TCE in the drinking water.
Several former workers told stories of workers getting injured or killed in explosions, having severe breathing and eye problems from the chemical fumes in the plant, and dipping their arms in large TCE vats to wash metal parts without the use of gloves or eye protection. According to some reports, safety precautions were not enforced or encouraged. There were descriptions of workers who, after working with a toxic pink powder all day at work, would go home covered in the powder which would then get into the carpets, drapes, towels, clothes, and hair of their children and would not wash out.
Some former workers stated that they contacted the Occupational Safety and Health administration (OSHA) on several occasions about the poor working conditions at the plant but for political reasons, they were not allowed to speak with OSHA representatives alone without their supervisors. They felt that this prevented OSHA from knowing about the poor safety conditions at the plant allowing for the continuation of more injuries on the job. Other workers stated they were afraid to say anything because they would lose their jobs.
OSHA has one investigation on record that was conducted in 1989. They found poor electrical set ups in the plant that were subsequently fixed. By law, OSHA is only able to address current existing problems at work sites. The OSHA is unable to currently address past occupational complaints of former Unidynamics workers particularly since the Unidynamics plant is now closed. According to the OSHA, a complaint can be filed with them anonymously and it will be followed up especially if more than two people call in. The OSHA tries to provide anonymity for employees who file a complaint by keeping their names, positions, and other employee identifying information unknown to the employer in question (OSHA 1999). The federal OSHA has a web site that reports the investigations that have been conducted at occupational facilities around the country.
5.4 ATSDR's Child Health Initiative
ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants and children demand special emphasis in communities faced with contamination of their water, soil, air, or food. Children are at greater risk than adults from certain kinds of exposures to hazardous substances emitted from waste sites and emergency events. They are more likely to be exposed because they play outdoors, they often bring food into contaminated areas, and the developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. HBGLs used in this report are specifically protective of childhood exposure for adverse health effects.
There are four major issues that relate to children living near the PGA North site. They are as follows:
In summary, there are many physical hazards in and around the irrigation canals that could pose a health threat to children who might play in the area. Since new housing developments are being built near these irrigation canal areas, it is important to secure these areas in such a way to prevent children from gaining access and getting hurt.
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