HEALTH CONSULTATION
Motorola 56th Street Facility
Phoenix, Maricopa County, Arizona
EPA Facility ID:
AZD980883300

Prepared by:
Arizona Department of Health Services
Under Cooperative Agreement with the
Agency for Toxic Substances and Disease Registry

Introduction
The purpose of this health consultation is to determine whether contaminants in groundwater
from the Motorola 56th Street facility represent a threat to public health.
Background
The Motorola 56th Street facility is located on the northwest corner of 56th Street and Earll Drive
in Phoenix, Arizona. The facility is in an area primarily surrounded by residential and commercial
property. The site is surrounded by single-family houses on the north, 56th Street on the east and
Earll Drive on the south. The 56th Street facility occupies about 14 acres of land that contain four
buildings, parking lots, and landscaped areas.
The facility is located in a suburban area of residential properties ranging from very small to
approximately 1 acre, with approximately 3000 persons living within 1 mile. Many homeowners
have lived in the homes for 20+ years. Some new homes have been built on previously vacant lots
or on properties recently subdivided.
The Motorola 56th Street facility was first occupied in the spring of 1950 as the Western Military
Electronics Center. From 1950 to 1958, it was primarily used for bench type electronics, electronic
assembly, and semiconductor production. The chemicals used in these processes included solvent
degreasers such as trichloroethylene, acetone, and freon, and metals such as cadmium, chromium,
and arsenic.1
From 1959 through 1961, the facility was used primarily for document storage. Beginning in 1962,
manufacturing of electronics resumed to include assembly of circuit boards, plating, and
degreasing. Chemicals used between 1962 and 1974 included trichloroethylene,
tetrachloroethylene, and a number of acids and metals including arsenic. In 1975, the facility began
manufacturing liquid crystal products. These activities continued until 1982, when it was
converted to office use. 1
The investigations that have been conducted to date have shown that there are residual levels of
arsenic and fluoride in down-gradient private wells west of the facility. Solvent contaminants that
were found in the 1980s are no longer present at detectable levels in down-gradient private wells.
Groundwater data from the affected area are currently available for 5 private irrigation wells downgradient (west) of the facility. All of the homes receive their drinking water from the city of
Phoenix municipal water system. There are no municipal production wells in the known area of
contamination. The closest currently operating public supply well is located 3.5 miles up-gradient
(east) of the facility.2
Attempts to locate the actual irrigation well sites at the private homes were undertaken on 4
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occasions: February 18, March 6, March 19, and March 20, 2003. ADHS staff located all of the 5
current well owners and spoke to the residents about the wells and their uses. In all cases, the
irrigation wells were specifically used to water outside plants, or were no longer being used. In
addition, the occupants were all aware of the non-potable nature of the water.
Discussion
Data Used
Comprehensive organic priority pollutant and inorganic chemical analyses were performed on
groundwater samples collected from 5 down-gradient irrigation wells in 1993. The samples were
analyzed for common volatile organic compounds and metals.3
Contaminants of Concern
This section identifies the chemicals of concern for the Motorola Inc. 56th Street facility. The
discussion addresses the available data; the methodology used in the identification process; the
criteria for selection; and determination of the extent and levels of contamination.
Groundwater
Table 1 displays the frequency and ranges of detection for the 2 compounds that were present in at
least one private well above the ATSDR Comparison Values of 3 µg/L for arsenic and 4 µg/L for
fluoride (The Arizona Department of Health Services used the U.S. Environmental Protection
Agency (EPA) Maximum Contaminant Level for Fluoride as a surrogate for a comparison value
(CV) because ATSDR does not have a CV for Fluoride). Solvent contaminants that were found in
the 1980s are no longer present at detectable levels in the wells. Only arsenic and fluoride are
present in water above an ATSDR CV or the EPA Maximum Contaminant Level. There are several
monitoring wells in the area placed to track the progress of the contaminants as they moved
through the aquifers. The sampling of these wells has indicated a steady decline in levels of the
industrial solvents in the groundwater.
Table 1. Private Well Sampling Results
Chemical

Frequency
of
Detection

Range
(µg/L)

ATSDR
Child
Comparison
Value (µg/L)

Arsenic
Fluoride

5/5
4/5

8-96
6-16

3
4*

Frequency of
Detection
Above
Comparison
Value
5/5
4/5

*USEPA Maximum Contaminant Level. No ATSDR Comparison Value Available
2

Contaminant
of Concern?

Yes
Yes

Exposure Pathways
It is possible that dermal, inhalation, and ingestion exposures have occurred and may continue
when residents irrigate their lawns and flowers and when children play in the irrigation water.
ADHS evaluated the environmental and human components that lead to human exposure to
determine whether people are exposed to contaminants from the site. An exposure pathway
consists of five elements: a source of contamination; transport through an environmental
medium; a point of exposure; a route of exposure; and a receptor population.
ADHS categorizes an exposure pathway as a completed or potential exposure pathway if the
exposure pathway cannot be eliminated. In completed exposure pathways, all five elements exist,
and exposure to a contaminant has occurred in the past, is occurring, or will occur in the future.
In potential pathways, at least one of the five elements is missing but could exist. Potential
pathways indicate that exposure to a contaminant could have occurred in the past, could be
occurring, or could occur in the future. This exposure assessment focuses on residents who live
west of the facility and have private irrigation wells. It estimates the types and magnitudes of
exposures to chemicals of potential concern and possible exposure pathways associated with
contamination detected at the site.
Complete Exposure Pathways
There are 5 known exposure points (private irrigation wells) to chemicals in the groundwater
plume. Complete exposure pathways are identified in Table 2. Exposure is through incidental
contact with irrigation water.
ADHS staff spoke to current residents who owned 5 irrigation wells, and all were aware of the nonpotable nature of the water from the wells. The water from the wells is used for outside watering
purposes such as for trees, flowers, and grass.
Table 2. Complete Exposure Pathways
Source

Motorola
56th St

EXPOSURE PATHWAY ELEMENTS
Media

Point of
Exposure

Route of
Exposure

Estimated
Population

COC

Groundwater

Exposure to
irrigation
water

ingestion
inhalation
dermal

30

Arsenic
Fluoride

3

COC = contaminant of concern
Groundwater
There are currently 5 wells near or in the area of known contamination. Table 3 lists the private
irrigation wells in the vicinity of the groundwater plume.
Exposures to irrigation water containing the chemicals of concern were estimated by assuming that
a child plays in the flood irrigation water once per week for a 4 hour time period. While playing in
the water, the child is assumed to incidentally ingest 0.05 liters (50 milliliters) during each play
event. The estimate assumes a standard child’s body weight of 15 kilograms. Inhalation and
dermal contact with the water did not contribute to the dose estimate because arsenic and fluoride
are inorganic, nonvolatile, and very poorly absorbed through the skin. Childhood doses were
compared to ATSDR Minimal Risk Levels, which are exposure doses below which no adverse,
non-cancer health effects are expected.
Table 3. Arsenic Dose Estimates and Minimal Risk Levels (MRLs)
Well Number

Arsenic
Concentration
(mg/L)

Child’s Estimated Daily
Dose
(mg/kg/day)

MRL
(mg/kg day)

Child Dose
Exceeds
MRL?

55-502277
55-638243
55-633954
55-639604
55-501995

0.016
0.008
0.025
0.027
0.096

0.000028
0.000016
0.00004
0.00004
0.00016

0.0003
0.0003
0.0003
0.0003
0.0003

No
No
No
No
No

Table 4. Fluoride Dose Estimates and Minimal Risk Levels (MRLs)
Well Number

Fluoride
Concentration
(mg/L)

55-502277
55-638243
55-633954
55-639604
55-501995

9
ND
7
6
16

Child’s Estimated Daily
Dose
(mg/kg/day)
0.016
-0.012
0.012
0.028
4

MRL
(mg/kg day)

Child Dose
Exceeds
MRL?

0.06
0.06
0.06
0.06
0.06

No
No
No
No
No

The exposure analysis suggests that incidental exposure to irrigation water at the 5 private
irrigation wells presents no public health hazard.

Child Health Issues
All exposure dose estimates were calculated assuming childhood exposure, thus incorporating
exposure assumptions that reflect a child’s greater intake of water relative to body weight. All
conclusions and recommendations about using water from these wells were based on the
characteristics of this sensitive population.
Conclusions
There are 5 private irrigation wells down-gradient of the Motorola 56th Street facility that have
elevated levels of arsenic or fluoride in the water. All the wells are used solely for flood irrigation,
and none are plumbed into the dwellings. Use of the private wells for flood irrigation poses no
public health hazard.
Recommendations
No recommendations
Public Health Action Plan
The Arizona Department of Health Services will notify the well owners of the results of this health
consultation.

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PREPARERS OF THE REPORT
Arizona Department of Health Services, Office of Environmental Health
Brian Hasty, MT
Will Humble, MPH
ATSDR Regional Representative
William Nelson
Office of Regional Operations, Region 9
Office of the Assistant Administrator
ATSDR Technical Project Officer
Gail Godfrey
Division of Health Assessment and Consultation
Superfund Site Assessment Branch
State Programs Section

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References
1. Kary Ray.. 1985. Chemical disposal methods report of Motorola Inc. 56th Street Facility,
Phoenix, Arizona.
2..Arizona Department of Environmental Quality Site and Hazard Evaluation Unit. 1991.
Site inspection of the Motorola 56th Street Facility.
3. Dames and Moore, Inc. 1993. Dry well abandonment report Motorola 56th Street
Facility. Phoenix, Arizona.

3. Certification
This Motorola 56th Street Facility Health Consultation was conducted by the Arizona Department
of Health Services in cooperation with the Agency for Toxic Substances and Disease Registry.
The health consultation was conducted in accordance to policy and guidance at the time the health
consultation was begun.

Technical Project Officer
ATSDR, DHAC, SSAB, SPS
This health consultation was reviewed by ATSDR. ATSDR concurs with the findings.

Chief, SPS

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