Health Consultation
Cooper Commerce (Unichem) Industrial Site
CERCLIS No. AZR000002550
Gilbert, Maricopa County, Arizona

Evaluation of Recent Data
From
Groundwater Monitoring Wells

Prepared by
Office of Environmental Health
Environmental Health Consultation Services
Arizona Department of Health Services
Under Cooperative Agreement With the
U.S. Department of Health and Human Services
Agency for Toxic Substances and Disease Registry (ATSDR)

Purpose
This health consultation evaluates tetrachloroethylene (perchloroethylene, perc, PCE) and
trichloroethylene (TCE) results obtained from groundwater monitoring wells in 2004. The
primary public health concerns were exposures to children by incidental contact with
groundwater used for watering yards and potential exposures from using groundwater for
drinking water. Another concern was contamination migrating beyond the site boundaries in two
groundwater aquifers.

Site Description
Cooper Commerce Industrial Park (CCIP) is located in Gilbert, Arizona, about 25 miles
southeast of Phoenix. The industrial park is comprised of mixed-use light and heavy industrial
enterprises, and is about 80 acres in size. It is located off Cooper Road, ½ mile south of
Guadalupe Road, in the 800 block of West Commerce Avenue (Appendix A). CCIP is adjacent
to other mixed-use industrial facilities along the rail line that serves the area. Residential
developments have been built to the west of the industrial area, across Cooper Road.
The initial discovery of PCE and TCE in shallow groundwater near the industrial park in 1990
led to an investigation to determine the sources of these contaminants. A large metal fabrication
enterprise at the east end of the business park was determined to be the source (J. Little, Arizona
Department of Environmental Quality, personal communication, August 11, 2004).
The primary groundwater contaminant, PCE, is used as a solvent in many of the industrial
operations common in CCIP. TCE was also found at concentrations near the maximum
contaminant level (MCL) of 5 micrograms/liter (µg/L). These contaminants were discarded in
dry wells or directly onto the ground before environmental regulations prohibited such disposal
practices. Although shallow groundwater contamination was initially discovered on this site in
1990, this site was not placed on the state’s Superfund (Water Quality Assurance Revolving
Fund) list until 2003 because of site ranking criteria.

Background
This area contains two groundwater aquifers. One is shallow, with water from 115–165 feet; the
other is deep, with water from 580–610 feet. Presently, there are no known connections between
these aquifers, and only the deep aquifer is used for drinking water supply.
In 1990, land surrounding CCIP was largely agricultural and the population of Gilbert was less
than 25,000. By 2004, about 125,000 people were living within the incorporated area of Gilbert.
This growth has placed a premium on all groundwater supplies within the town limits. Gilbert
currently uses the deep groundwater aquifer for 25% of its water supply. Water in the shallow
aquifer is affected by PCE and TCE, but this aquifer is not used for drinking water at this time.
Arizona groundwater regulations consider all groundwater to be of drinking water quality, even
if at the present time the water is not potable. Therefore, the contaminated aquifer has the
potential to be a future drinking water source (ADEQ 1992).

1

Prolonged drought conditions extending back about 9 years, and expected to continue for several
more years, have placed a strain on surface water supplies. This demand on surface water
sources may result in some shallow, otherwise unused groundwater sources being tapped for
drinking water. The closest drinking water well is presently located within ½ mile down-gradient
of the plume of the contaminants. This well is drilled into the deep aquifer, in which neither PCE
nor TCE have been detected.

Groundwater Contamination
Both PCE and TCE were found in a Salt River Project (SRP) irrigation well located adjacent to
CCIP in June 2001. This well is drilled 615 feet into the deeper aquifer and has a 24-inch
perforated case from 210 to 580 feet. The SRP well is currently used to supply irrigation water to
local users (Personal Communication with Dr.Greg Elliott, SRP water quality expert, October
15, 2004). PCE and TCE levels in this well were below the respective MCL (5 µg/L) for each
chemical, but there was concern about groundwater contamination spreading beyond the
boundaries of the industrial park. The perforated casing of the SRP well is below the shallow
aquifer. To the best of our knowledge, the SRP well does not provide a connection between the
shallow and deep aquifers.
In response to finding PCE and TCE in the SRP irrigation well, two monitoring wells (104S and
104D) were installed about 1,000 feet north of CCIP in July 2003. These wells are located
between the contaminated area of the shallow aquifer and the nearest drinking water supply
well. The closest drinking water well is about ½ mile north of CCIP, near the intersection of
Guadalupe and Cooper Road, and is drilled into the deeper aquifer. Groundwater flows to the
northwest and this drinking water well is in the path of contaminants that could be carried offsite. To date, neither PCE nor TCE have been detected in this well.
Monitoring well 104S was drilled approximately 125 feet below ground surface into the shallow
aquifer where PCE and TCE were initially found. Monitoring well 104D was drilled into the
deeper aquifer from which drinking water is presently drawn.

Data Used
Monitoring Well Data
Monitoring wells 104S and 104D were sampled in August, September, and December of 2003,
and March 2004. Table 1 shows the levels of PCE and TCE found in these wells. PCE and TCE
were not detected in samples collected from monitoring well 104D, which is in the deep aquifer
used for drinking water supply.

2

Table 1. Data for recently installed monitoring wells in Gilbert, Arizona (ADEQ 2004)
PCE (µg/L)*
Date
8/7/03
9/4/03
12/8/03
3/10/04
Date
8/7/03
9/4/03
12/8/03
3/16/04

TCE (µg/L)*
MW104D (deep)
<2.0
<2.0
<2.0
<2.0
MW104S (shallow)
6
3.6
4.5
2.4

<2.0
<2.0
<2.0
<2.0
16
5.8
17
10

* Numbers in bold exceeded maximum contaminant levels (MCLs) of
5 µg/L for tetrachloroethylene (perchloroethylene, perc, PCE) and
trichloroethylene (TCE).

Drinking Water Well Data
Neither PCE nor TCE have been detected in the nearest drinking water supply well.

Contaminants of Concern
The primary contaminant of concern in shallow groundwater is PCE, which was found at more
than 3 times the U.S. Environmental Protection Agency (EPA) MCL of 5 µg/L (EPA, 1992).
TCE slightly exceeded the EPA MCL of 5 µg/L in one sample (Table 1).

Exposure Analysis
This section analyzes the exposure pathways by which children and adults may come into
contact with contaminated water in the irrigation canals. The analyses use ATSDR and ADHS
standard exposure assumptions for intake rates, body weights, exposed skin surface area,
averaging times, and exposure duration. Equations and exposure factors are provided in
Appendix B. Table 2 shows the current EPA MCL, the ADEQ noncancer health-based guidance
levels (HBGLs) (ADHS, 1996), and the ATSDR oral Minimal Risk Levels (MRLs), (ATSDR
2004).
Table 2. EPA maximum contaminant levels (MCLs), ADEQ health-based guidance levels
(HBGLs) for flood irrigation, and ATSDR oral minimal risk levels (MRLs) for PCE and
TCE
Chemicals of Concern

MCLs (µg/L) HGBLs (µg/L) Oral MRLs (mg/kg/day)

Tetrachloroethylene
(perchloroethylene, PCE)

5

170

0.05 (acute)*

Trichloroethylene (TCE)

5

920

0.2 (acute)*

*No chronic MRLs currently available.

3

Our exposure analysis focused on use of contaminated water for flood irrigation of yards in
neighborhood residences, with child exposures being the primary concern. Flood irrigation
adequate to maintain Bermuda grass was used to quantify water applications (K. Tiggs, R.
Templeton, City of Phoenix Parks and Recreation Department, personal communication, January
22, 1998). An irrigation frequency of 24 days per year was used. The duration of each irrigation
flood event was assumed to be 4 hours. These are considered to be independent acute exposures.
We used EPA standard default assumptions to calculate potential exposures from contaminants
in flood irrigation water. Inhalation exposures were calculated using a mass transfer model for
bodies of water (EPA 1995). We also used primarily EPA standard default exposure assumptions
to quantify potential exposures to nearby residents.
Estimating wind dispersion of these contaminants was done by applying the EPA Q/C dispersion
term for Phoenix, Arizona. Q/C is the inverse concentration factor for air dispersion (EPA 1996
b). The model uses the inverse of the mean concentration at the center of a 0.5-acre body of
water. Skin absorption of the contaminants is quantified using chemical-specific permeability
coefficients (EPA 1992).
Skin contact and inhalation pathways were assessed using the ADHS noncancer HBGLs for
incidental contact end uses of water developed for the State of Arizona (ADHS 1996). HBGLs
are calculated using a human health-based approach generally consistent with risk assessment
methodologies recommended by EPA and ADHS. These guidance levels use standard default
exposure assumptions. Where necessary, the levels reflect conservative assumptions based upon
research of the particular exposure scenario and professional judgment. Equations used to
quantify exposures were based upon generally accepted methods, models, toxicity values, and
assumptions developed by EPA. The standard exposure assumptions were obtained primarily
from Risk Assessment Guidance for Superfund (RAGS), Supplemental Guidance Standard
Default Exposure Factors (EPA 1990).
HBGLs are individually protective of human health, including sensitive groups, over a lifetime.
Chemical concentrations for a particular exposure use that exceed the applicable HBGL may not
necessarily represent a health risk. Rather, when contaminant concentrations exceed the HBGL,
further evaluation may be necessary to determine whether using groundwater for the given purpose
poses an unacceptable risk to human health.
HBGLs consider human health risks from inhalation, ingestion, and skin contact with chemicals in
groundwater. ADEQ plans to include HBGLs as the human health-based criteria in the final end use
standards for groundwater that will be protective of human health and the environment, including
groundwater and the ecology.
The methods used to calculate noncancer HBGLs are conservative, which means that equations
and assumptions tend to over-estimate risk. For example, the equations that quantify exposures
do not consider attenuation of contaminants over time. Additionally, for scenarios with serial
exposure pathways and routes, such as flood irrigation, the equations assume that no contaminant
mass is lost before the last exposure in the series.

4

Our residential exposure scenario assumes that adults and children are exposed to contaminated
irrigation water by inhalation, ingestion, and skin contact during periodic flood irrigation of
yards. We also considered that children be exposed to contaminants by playing in canal water.
Children are assumed to play in the irrigation water for a total of 4 hours/day, 24 days/year, for
12 years.
This is based upon the premise that the yard is flooded once per week for a 6-month period,
which is the normal irrigation schedule for the properties that receive flood irrigation water. The
child in our scenario is exposed through incidental ingestion and skin contact with the
contaminants in the water for a 4-hour period during each irrigation event (EPA 1989). The adult
is exposed by inhalation of contaminants escaping from the flood irrigation waters for the 4
hours that the water is assumed to be standing on the property (K. Tiggs, R. Templeton, City of
Phoenix Parks and Recreation Department, personal communication, January 22, 1998). This
scenario is considered to be a series of independent acute exposure events because these
chemicals do not bioaccumulate.
PCE
As noted in Table 2, the HBGL for PCE in flood irrigation water is 170 µg/L. The highest PCE
level found in samples from the SRP irrigation well was 10 times less than the HBGL (Table 3).
To estimate exposure, we assumed a child might play in flood irrigation water containing PCE
for a 4-hour period, 1 day per week, for 6 months each year over 12 years. A child is assumed to
incidentally ingest 0.05 liters (50 milliliters) during each play event. We used a standard child
body weight of 15 kilograms (kg) (EPA 1992). The highest chemical concentration detected was
used to represent a worst-case exposure scenario. This scenario is considered to be a series of
acute exposure events.
Table 3. Comparison of PCE* Concentrations in MW104S to the HBGL†
Exposure Pathways

Private Well Use

Highest PCE Level

HBGL

HBGL
Exceeded?

Ingestion, Inhalation,
Dermal

Irrigation of yards

17 µg/L‡

170 µg/L

No

*PCE=tetrachloroethylene; † HGBL= noncancer health-based guidance level. These HGBLs assume that adults and children are
exposed to the contaminated irrigation water 24 days per year; ‡ µg/L = micrograms per liter.

The ingested dose from flood irrigation water was doubled to take into account skin absorption
and inhalation of vapors resulting from contact with the irrigation water. The assumption is that
the combined dose from these two routes of exposure is equivalent to that of ingestion. Appendix
B shows the calculations to determine the HGBL for exposures to PCE from the flood irrigation
water.

5

We compared the estimated child exposure dose for PCE to the acute ATSDR MRL for oral
ingestion of PCE. MRLs are levels at which no adverse, noncancer health effects are expected.
Our estimated child exposure dose was 25 times below the MRL of 0.05 mg/kg/day (Table 4).
Our estimated child exposure dose was also 5 times below the EPA chronic reference dose (RfD)
of 0.01 mg/kg/day.
Table 4. Comparison of Estimated Child Exposure Dose to PCE* with ATSDR MRL†
Exposure
Pathways
Ingestion,
Inhalation,
Dermal

Private Well
Use

Estimated Exposure
Dose‡

MRL†

MRL Exceeded?

Irrigation of
yards

0.0002 mg/kg/day

0.05 mg/kg/day (acute)

No

*PCE = tetrachloroethylene;
the assumed ingestion dose.

†

MRL = ATSDR minimal risk level. ‡Total dose from all pathways was calculated by doubling

TCE
As noted in Table 2, the HGBL for TCE in flood irrigation water is 920 µg/L. The highest TCE
level from our monitoring well samples was about 153 times below the HBGL (Table 5).
Table 5. Comparison of TCE* Concentrations in MW104S with HBGL†
Exposure Pathways

Private Well Use

Highest PCE Level

HBGL

HBGL Exceeded?

Ingestion, Inhalation,
Dermal

Irrigation of yards

6 µg/L

920 µg/L

No

*TCE = trichloroethylene; † HGBL= health-based guidance level. This HBGL assumes that adults and children are exposed to
the contaminated irrigation water 24 days per year; ‡ µg/L = micrograms per liter.

Child exposures to irrigation water containing TCE were estimated in the same manner
previously described for PCE. Calculations to determine the HGBL for exposures to TCE from
the flood irrigation water are shown in Appendix B.
The estimated child exposure dose for TCE was compared to the acute ATSDR MRL for oral
ingestion of TCE. MRLs are levels at which no adverse, noncancer health effects are expected.
Our estimated child exposure dose was about 1,000 times less than the acute MRL (Table 6).
There is currently no EPA chronic RfD for this chemical. Our scenario considers the typical type
of exposure to be a series of independent exposure events.

6

Table 6. Comparison of Child Estimated Exposure Dose to TCE* in Irrigation Water With
ATSDR MRL†
Exposure
Pathways
Ingestion
Inhalation
Dermal

Private Well Use

Estimated Exposure
Dose‡

MRL

MRL Exceeded?

Irrigation of yards

0.00006 mg/kg/day

0.2 mg/kg/day (acute)

No

†

‡

* TCE = trichloroethylene; MRL= ATSDR minimal risk level; Total dose from all pathways was calculated by doubling the
assumed ingestion dose.

Cancer
EPA is currently re-evaluating the carcinogenic classification for TCE. There is currently no
cancer risk evaluation guide available for TCE or PCE. The International Agency for Research
on Cancer has determined that TCE is a probable human carcinogen. That determination is based
on limited human data and sufficient data in experimental animals (ATSDR 2001). At the
Cooper Commerce Site, exposures to TCE and PCE, if they occur, are infrequent and to very low
levels. No increased risk of cancer is expected as a result of these exposures.

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. The highest concentration of TCE or PCE in the
contaminated groundwater would not be considered to cause adverse health effects when used
for irrigation purposes in the yards.
ADHS used the noncancer health effects calculations with intermediate duration exposures to
estimate the childhood exposures, and the use of the HBGLs to determine if any adverse health
effects would result.

Conclusions
Use of the SRP irrigation well for flood irrigation purposes poses no public health hazard.
Estimated exposure doses for ingesting contaminated water from the SRP irrigation well were
below those associated with adverse health effects. The SRP well is used solely for flood
irrigation.
Although water in the shallow aquifer is contaminated with PCE and TCE at levels above the
MCLs, this water is not currently used for drinking water purposes.

7

PCE and TCE were not detected in new wells located between the site and the nearest drinking
water wells drilled into the deep aquifer.
Drinking water supplied from Gilbert’s municipal well currently meets all federal and state
standards indicating that the water is safe. Contaminants associated with this site have not been
detected in an aquifer currently used for drinking water. Future use of the shallow aquifer for
drinking water purposes raises the question of future exposures.
The levels of tetrachloroethylene (perchloroethylene, perc, PCE) and trichloroethylene (TCE) in
the irrigation well would not be considered a health hazard to children who might play in or
otherwise contact the irrigation water.

Recommendations
Continue monitoring of the lower aquifer data collected by ADEQ to determine if the
contaminants will affect the drinking water supply.

Public Health Action Plan
ADHS will review follow-up sampling results.
ADHS will work with the ADEQ to keep the public informed about sampling results.

References
[ADEQ] Arizona Department of Environmental Quality. 1992. Aquifer Water Quality Standards
in Reclassified Aquifers. Arizona Administrative Code Title 18, Chapter 11, Article 407,
Revised 1992. Available at URL: http://www.azsos.gov/public_services/Title_18/18-11.htm.
[ADEQ] Arizona Department of Environmental Quality. 2004. Quarterly report for Cooper
Commerce monitoring wells. Phoenix: Arizona Department of Environmental Quality.
[ADHS] Arizona Department of Health Services. 1996 Health –based guidance levels for noncancer health effects. Phoenix: Arizona Department of Health Services .
[ATSDR] Agency for Toxic Substances and Disease Registry. 2001 Jan. Case studies in
environmental medicine: trichloroethylene (TCE) toxicity (revised). Atlanta: US Department of
Health and Human Services. Available at URL:
http://www.atsdr.cdc.gov/HEC/CSEM/tce/index.html
[ATSDR] Agency for Toxic Substances and Disease Registry. 2004. Minimal risk levels (MRLs)
for hazardous substances. Available at URL: http://www.atsdr.cdc.gov/mrls.html.
[EPA] US Environmental Protection Agency. 1989. Risk assessment guidance for Superfund
(RAGS). Volume 1, Human health evaluation manual (part A), interim final. EPA/540/1-89/002.
8

Washington, DC: US Environmental Protection Agency. Available at URL:
http://www.epa.gov/superfund/programs/risk/ragsa/index.htm.
[EPA] US Environmental Protection Agency. 1990. Exposure factors handbook.
EPA/600/8089/043. Washington, DC: US Environmental Protection Agency.
[EPA] US Environmental Protection Agency. 1991. Risk assessment guidance for Superfund
(RAGS), supplemental guidance standard default exposure factors. Washington, DC: US
Environmental Protection Agency.
[EPA] US Environmental Protection Agency. 1992. Dermal exposure assessment: principles
and applications. EPA/600/8-91/011B. Washington, DC: US Environmental Protection
Agency. Available at URL: http://www.epa.gov/nceawww1/pdfs/derexp.pdf.
[EPA] US Environmental Protection Agency. 1992. Maximum contaminant levels for
drinking water. Washington D. C: US Environmental Protection Agency. Available at URL:
http://www.epa.gov/safewater/mcl.html#mcls
[EPA] US Environmental Protection Agency. 1995. Air/Superfund national technical
guidance study series. Guideline for predictive baseline emissions estimation for Superfund
sites, ASF-21. EPA/451/R-96/001. Research Triangle Park: US Environmental Protection
Agency.
[EPA] US Environmental Protection Agency. 1996b. Soil screening guidance: user's guide.
EPA/540/R-96/018 (PB96-963505). Washington, DC: US Environmental Protection Agency.
Available at URL: http://www.epa.gov/superfund/resources/soil/introtbd.htm.
[EPA] US Environmental Protection Agency. 2004. Region IX preliminary remediation goals
(PRGs). San Francisco: US Environmental Protection Agency. Available at URL:
http://www.epa.gov/region9/waste/sfund/prg/files/04prgtable.pdf.
[EPA] US Environmental Protection Agency. 1997. Health effects assessment summary
tables (HEAST): annual update, FY 1997. EPA/540/R-97/036. Cincinnati: US Environmental
Protection Agency.
[EPA] US Environmental Protection Agency. 1998. Integrated Risk Information System
(IRIS). Duluth: US Environmental Protection Agency. Available at URL:
http://www.epa.gov/iriswebp/iris/index.html.

9

CERTIFICATION
The Arizona Department of Health Services, under a cooperative agreement with the Agency for
Toxic Substances and Disease Registry (ATSDR), prepared this health consultation on Cooper
Commerce Industrial Park. This consult was prepared in accordance with approved methodology
and procedures existing at the time.

____________________________________
Allen Robison
Technical Project Officer
Superfund and Program Assessment Branch
Division of Health Assessment and Consultation

The Division of Health Assessment and Consultation has reviewed this health consultation and
concurs with its findings.

_________________________________
Bobbie Erlwein
Team Leader, Cooperative Agreement Team
Superfund and Program Assessment Branch
Division of Health Assessment and Consultation
ATSDR

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Appendix A
Site Maps

Regional Location Map adapted from
http://www.ci.gilbert.az.us/generalplan/regional-vicinity.html
Location of Unichem International Map adapted from www.mapquest.com
Map of Well Locations adapted from
http://www.ci.gilbert.az.us/generalplan/public-facilities.html

Regional Location Map

Location of Unichem International

Unichem

11

Location of New Monitoring Wells, Salt River Project Well and Gilbert Wells
(adapted from http://www.ci.gilbert.az.us/generalplan/public-facilities.html)
Unichem
International (x)

Gilbert Well (●)

New Monitoring
Wells

Salt River Project
(SRP) Well (●)

12

Appendix B
Exposure Dose Equations
Tetrachloroethylene (perchloroethylene, perc, PCE) and trichloroethylene (TCE) have been
detected in the shallow aquifer below Gilbert, Arizona. People could be exposed to those
contaminants in water from the aquifer. The Arizona Department of Health Services (ADHS)
used Agency for Toxic Substances and Disease Registry (ATSDR) guidance documents to
calculate potential exposure doses for people exposed to that water. The doses were calculated
using the following equations:
Ingestion of chemicals in water:
EED =

CW x IR x EF
BW

EED: Estimated exposure dose (mg/kg/day)
CW: Contaminant concentration in water (mg/L)
IR:
Water intake rate (L/day)
EF: Exposure factor
BW: Body weight (kg)
-----------------------------------------------------------------CW =

0.017 mg/L (PCE)

0.006 mg/L (TCE)

IR:
BW:

Adults
2 L/day
70 kg

Children
1 L/day
15 kg

EF = Annual Exposure Frequency x Annual Exposure Duration x No. of Years of Exposure
Averaging Time
Child EF =

1 day/week x 24 weeks/year x 12 yrs = 288 days = 0.066
12 yrs x 365 days/yr
4,380 days

Child EED= 0.017 mg/L (PCE) x 1 L/day x 0.066 = 0.0011 = 0.000075 mg/kg/day
15 kg
15
Adult EF also equals 0.066
Adult EED = 0.017 mg/L (PCE) x 1L/day x 0.066 = 0.0011 = 0.000016 mg/kg/day
70 kg
70
Child EED= 0.006 mg/L (TCE) x 1L/day x 0.066 = 0.0004 = 0.00003 mg/kg/day
15 kg
15

13

Adult EED = 0.017 mg/L (TCE) x 1L/day x 0.066 = 0.0004 = 0.000006 mg/kg/day
70 kg
70

Conclusions
Using conservative exposure assumptions, the estimated exposure doses for children and
adults to PCE and TCE in irrigation water are well below respective minimal risk levels or
reference dose values.

Landscape Flood Irrigation
Childhood ingestion of volatile organic compounds, noncancer
Cw 2 ( µ g/L) =

HQ x BW ch x AT nc x RfD o x CF5
IR w x IT ing x EF ing x ED ch

Parameter

Definition (units)

Default

Reference

HQ

Hazard Quotient, (unitless)

1

ADHS 1997

BWch

Body Weight, child (kg)

15

EPA 1989

ATnc

Averaging Time, noncancer (days)

2,190

EPA 1989

RfDo

Reference Dose, oral (mg/kg/day)

ChemicalSpecific

EPA 1997, 1998,
or NCEA

CF5

103 (µg/mg)

1,000

---------------

IRw

Ingestion Rate, water (L/hour)

0.05

EPA 1991

ITing

Irrigation Time, ingestion (hours/day)

4

ADHS 1998

EFing

Exposure Frequency, ingestion
(days/year)

33

COP 1998

EDch

Exposure Duration, child (years)

6

EPA 1991

ADD CORRECT REFERENCES THAT CORRESPOND TO LISTINGS IN MAIN
REFERENCE SECTION. COP 1998 IS PERSONAL COMMUNICATION; ADD
FOOTNOTE HERE. IRIS WOULD BE EPA 1998; HEAST WOULD BE EPA 1997;
NCEA = ???. ADHS 1997 AND 1998 NEED TO BE ADDED OR REVISED.

14