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PETITIONED PUBLIC HEALTH ASSESSMENT


PHELPS DODGE CORP DOUGLAS REDUCTION WORKS
DOUGLAS, COCHISE COUNTY, ARIZONA




APPENDIX A - FIGURES

LIST OF FIGURES

FIGURE 1 - UNITED STATES GEOLOGICAL SURVEY MAP OF DOUGLAS, AZ

FIGURE 2 - MEAN INHALABLE PARTICULATE MATTER LEVELS

FIGURE 3 - HIGHEST ANNUAL TSP MEANS

FIGURE 4 - HIGHEST ANNUAL SULFUR DIOXIDE MEANS


Figure 1 - United States Geological
Survey Map of Douglas, AZ



Figure 2 - Mean Inhalable Particulate
Matter Levels



Figure 3 - Highest Annual TSP Means



Figure 4 - Highest Annual Sulfur
Dioxide Means


APPENDIX B - TABLES

LIST OF TABLES

TABLE 1A - CONTAMINANT CONCENTRATIONS IN ON-SITE SLAG PILE

TABLE 1B - CONTAMINANT CONCENTRATIONS IN ON-SITE SURFACE SOIL PRIOR TO REMOVAL

TABLE 1C - CONTAMINANT CONCENTRATIONS IN ON-SITE SURFACE SOIL

TABLE 2A - CONTAMINANT CONCENTRATIONS IN ON-SITE GROUNDWATER

TABLE 2B - CONTAMINANT CONCENTRATIONS IN ON-SITE SURFACE WATER

TABLE 3 - CONTAMINANT CONCENTRATIONS IN ON-SITE AIR

TABLE 4 - CONTAMINANT CONCENTRATIONS IN OFF-SITE RESIDENTIAL SOIL

TABLE 5 - CONTAMINANT CONCENTRATIONS IN OFF-SITE GROUNDWATER

TABLE 6 - CONTAMINANT CONCENTRATIONS IN WHITEWATER DRAW

TABLE 7 - CONTAMINANTS CONCENTRATIONS IN OFF-SITE AIR

TABLE 8 - PHELPS-DODGE PATHWAYS SUMMARY

TABLE 9 - SUMMARY OF BIOMONITORING DATA FOR DOUGLAS, AZ

TABLE 10 - OTHER HEALTH OUTCOME DATA FOR DOUGLAS, AZ

TABLE 1A.

CONTAMINANT CONCENTRATIONS IN ON-SITE SLAG PILE
CONTAMINANTMAXIMUM CONCENTRATION (mg/kg)BACKGROUND RANGE (mg/kg) SOURCEYEAR
copper8062-300bkgrn1989
lead80400EPA1989

TABLE 1B.

CONTAMINANT CONCENTRATIONS IN ON-SITE SURFACE SOIL PRIOR TO REMOVAL
ContaminantMaximum concentration (mg/kg)Mean concentration (mg/kg)Comparison value (mg/kg) SourceYear
arsenic184042220EMEG1989
cadmium25012450000EMEG1989
chromium30.318300EMEG1989
copper1640001080002-300bkgrnd1989
lead60501671400EPA1989

TABLE 1C:

CONTAMINANT CONCENTRATIONS IN ON-SITE SURFACE SOIL
CONTAMINANTMAXIMUM CONCENTRATION (mg/kg)COMPARISON VALUE (mg/kg) SOURCE YEAR
arsenic 118 0.6EMEG 1995
cadmium 63.2 1.0EMEG 1995
chromium 44.4 10.0RMEG 1995
copper 13200 * * 1995
lead 1220 400EPA 1995
mercury 4.5 4EMEG 1995

* no comparison value available

TABLE 2A:

CONTAMINANT CONCENTRATION IN ON-SITE GROUND WATER
CONTAMINANTMAXIMUMCONCENTRATION (mg/L) COMPARISON VALUE (mg/L) SOURCEYEAR
arsenic0.04320.003 EMEG1989
copper0.0358 1.3 MCL1989
lead0.00270.015 MCL1989

TABLE 2B:

CONTAMINANT CONCENTRATIONS IN ON-SITE SURFACE WATER
CONTAMINANTMAXIMUM CONCENTRATION (mg/L)COMPARISON VALUE (mg/L) SOURCEYEAR
arsenic 0.014 0.003EMEG 1995
copper 0.061 1.3MCL 1995
lead 0.021 0.015MCL 1995

TABLE 3.

CONTAMINANT CONCENTRATIONS IN ON-SITE AIR
CONTAMINANTMAXIMUMCONCENTRATION (fibers/cc) COMPAR.VALUE (fibers/cc)SOURCECARCIN. CLASSCOMPAR. VALUE EXCEEDED?
asbestos0.9240.1RELAYes

Table 4.

CONTAMINANT CONCENTRATIONS IN OFF-SITE RESIDENTIAL SOIL
CONTAMINANTMAXIMUM CONCENTRATION (mg/kg)MEAN CONCENTRATION (mg/kg)COMPARISON VALUECOMP. VALUE EXCEEDED?YEAR
(mg/kg)SOURCE
lead1170254400EPAYes1985
lead564172400EPAYes1989
arsenic35.81520EMEGYes1989
cadmium13.7550000EMEGNo1989
chromium1512300EMEGNo1989
copper533016702 - 300bkgrnYes1989

TABLE 5:

CONTAMINANT CONCENTRATIONS IN OFF-SITE GROUNDWATER
CONTAMINANTMAXIMUM CONCENTRATION (mg/l)COMPAR. VALUE (mg/l)SOURCECARCIN. CLASSCOMP. VALUE EXCEEDED?YEAR
arsenic0.0010.00002CREGAYes1984
barium0.080.7RMEG
No1984
cadmium0.0020.002CREG
No1984
chromium0.0030.1MCLG
No1984
lead0.020.015MCLGB2Yes1984
mercury0.00010.002LTHA
No1984
selenium0.0230.03EMEG
No1984
silver0.0030.05RMEG
No1984
zinc0.082.1LTHA
No1984

Table 6.

CONTAMINANT CONCENTRATIONS IN WHITE WATER DRAW
CONTAMINANTMAXIMUM CONCENTRATION (MG/L)COMPAR. VALUE (MG/L)SOURCECARCIN. CLASSCOMP. VALUE EXCEEDED?
arsenic0.10.003RMEGAYes
barium3.330.7RMEG
Yes
cadmium0.0310.002EMEG
Yes
chromium0.50.1MCLG
Yes
copper0.711.3MCLG
No
lead0.360.015MCLGB2Yes
manganese8.941RMEG
Yes
mercury0.0020.002LTHA
No
selenium0.2580.03EMEG
Yes
zinc1.142.1LTHA
No

Table 7.

CONTAMINANT CONCENTRATIONS IN OFF-SITE AIR
CONTAMINANTMAXIMUM CONCENTRATION (mg/m³)COMPAR. VALUE (mg/m³)SOURCECARCIN. CLASSCOMP. VALUE EXCEEDED?
arsenic0.0001212.3E-07CREGAYes
benzene0.01080.0001CREGAYes
cadmium7.8E-055.6E-07CREGB1Yes
cobalt2.5E-05



copper0.0081



lead1.18E-050.0015NAAQS


No
manganese0.00053E-07EMEG
Yes
nickel0.0001

A
particulates1.756



PM100.2210.05NAAQS
Yes
sulfur dioxide 10 (3hr)0.365NAAQS(3hr)
Yes
zinc0.0043



Table 8.

PHELPS-DODGE PATHWAYS SUMMARY
COMPLETED PATHWAYS
PATHWAY NAME:AMBIENT AIRSURFACE SOILOCCUPATIONAL EXP.
Source:Smelter EmissionsSmelter Emissionsdemolition wastes
Environmental Medium:Airsoil and dustair
Exposure Point:residential areasresidential areason-site
Exposure Route:Inhalationingestion
inhalation
inhalation
ingestion
Receptor Population:Adults and ChildrenAdults & Childrenworkers
Exposure Duration:ChronicChronicintermediate
Time Period:Pastpast, present, futurepast
Contaminants of Concern:Arsenic, cadmium, lead, PM10, SO2, ManganeseLeadasbestos
Estimated Number Exposed (see demographics section)Douglas + Agua Prieta: 90,000
within 1 mile: 200
90,000
Pirtleville: 1200
Douglas < 18: 4359
unknown
POTENTIAL PATHWAYS
PATHWAY NAME:SURFACE WATERFOOD CHAINSOIL/DUSTGROUNDWATER
Source:slag/leachatesmelter emissions
car emissions
smelter emissions
car emissions
smelter
groundwater
Environmental Medium:surface waterfood chaindustOff-site municipal wells
Exposure Point:White Water Drawplants & livestockinside homes
Exposure Route:ingestioningestion ingestion/inhalationingestion
Receptor Population:childrenconsumersadults & childrenadults & children
Exposure Duration:acuteintermediatechronicchronic
Time Period:pastpast, present, futurepast, present, futurepast, present, future
Contaminants of Concern:metalsleadleadarsenic, lead
ELIMINATED PATHWAY
PATHWAY NAME:SLAG PILE
Source:smelter
Environmental Medium:slag
Exposure Point:on site
Exposure Route:*
Receptor Population:*

Table 9.

SUMMARY OF BIO MONITORING DATA FOR DOUGLAS, AZ
DATEHEALTH OUTCOMEPARAMETERDATACOMPARISON VALUE(Reference Number)
VALUESOURCE
1985Mean Blood Lead Levels, childrenPica children
(n = 10)
11.5ug/dl10 ug/dlCDC(4)
non-Pica children
(n = 104)
13.1ug/dl10 ug/dlCDC
0 - 2 miles from stack
(n = 40)
13.7ug/dl10 ug/dlCDC
2 - 5 miles from stack
(n = 74)
12.7ug/dl10 ug/dlCDC
Urine Arsenic Levels, childrenpercent above normal4.5%
(n = 6)
50 ug/L(normal)CDC
percent above excessive exposure level 1.4%
(n = 2)
100 ug/L (excessive level)CDC
1975Mean Hair Arsenic Levels, children 1-5 years oldDouglas
(n = 95)
0.43ug/g1.0 ug/gATSDR(16)
Mean Urine Arsenic LevelsDouglas
(n = 95)
18.7ug/L50 ug/LCDC
Mean Blood Lead LevelsDouglas
(n = 95)
20.47ug/dl10 ug/dlCDC
Mean Hair Lead LevelsDouglas
(n = 95)
25.94ug/g
Hair Cadmium LevelsDouglas
(n = 95)
1.72ug/g

Table 10.

OTHER HEALTH OUTCOME DATA FOR DOUGLAS, AZ
DATEHEALTH OUTCOMEPARAMETERDATA(Reference Number)
1992Special Education, (incuding learning disabled and mentally handicapped) listed as percentage of enrolled studentsSarah Miley Elementary11% (34)
Clawson Elementary8%
Faras Elementary15%
A Avenue Elementary10%
1979Total number lung cancer cases 1970 -1977Douglas, Az population56(17)
Lung cancer Standard Mortality Ratio (SMR)males in DouglasSMR = 161
females in DouglasSMR = 130
Lung cancer casesmales < 7 km from smelter20
males > 15 km from smelter28
females < 7 km from smelter5
females > 15 km from smelter3

APPENDIX C - COMPARISON VALUES

Comparison Values

When conducting public health assessments, ATSDR uses comparison values -- contaminantconcentrations in specific media -- to select contaminants for further evaluation. The valuesprovide guidelines for estimating a dose at which health effects might be seen. Comparisonvalues used in the Environmental Contamination and Other Hazards and the Public HealthImplications sections of this public health assessment are listed and described in the followingparagraphs.

* CREG= Cancer Risk Evaluation Guides
* DWEL= Drinking Water Equivalent Level (µg/L)
* EMEG= Environmental Media Evaluation Guides
* MCL = Maximum Contaminant Level (µg/L)
* MCLG= Maximum Contaminant Level Goal (µg/L)
* MRL = Minimal Risk Level (mg/kg/day)
        IMRL=Intermediate Risk Level
        CMRL=Chronic Risk Level
* PEL= Permissible Exposure Limit (mg/m3)
* REL= Recommended Exposure Limit (mg/m3)
* RfD= Reference Dose (mg/kg/day)
* RfC= Reference Concentration (mg/m3)
* ppm= milligrams per liter (mg/L water)
       milligrams per kilogram (mg/kg soil)
* ppb= micrograms per liter (µg/L water)
       micrograms per kilogram (µg/kg soil)
* kg= kilogram
* mg= milligram
* µg= microgram
* pg= picogram
* L = liter
* m3= meters cubed
* NAAQS = National Ambient Air Quality Standards

Cancer Risk Evaluation Guides (CREGs) are estimated contaminant concentrations that would beexpected to cause no more than one excess cancer in a million persons (10E-6) exposed over alifetime. CREGs are calculated from EPA's cancer slope factors.

The drinking water equivalent level (DWEL) is a lifetime exposure level specific for drinkingwater (assuming that all exposure is from that medium) at which adverse, noncancer health effectsare not expected.

Environmental Media Evaluation Guides (EMEGs) are calculated from ATSDR minimal risklevels (MRLs); they consider body weight and ingestion rates.

Maximum Contaminant Levels (MCLs) are contaminant concentrations that EPA deemsprotective of public health (considering the availability and economics of water treatmenttechnology) over a lifetime (70 years) at an exposure rate of 2 liters of water per day (for anadult).

Maximum Contaminant Level Goals (MCLGs) are drinking water health goals set at levels atwhich no known or anticipated adverse effect on the health of persons is expected and whichallow an adequate margin of safety. Such levels consider the possible impact of synergisticeffects, long-term and multi-stage exposures, and the existence of susceptible groups in thepopulation. When there is no safe threshold for a contaminant, the MCLG should be set at zero.

A Minimal Risk Level (MRL) is an estimate of daily human exposure to a chemical (in mg/kg/day)likely to be without an appreciable risk of deleterious effects (noncancer) over a specified durationof exposure. MRLs are derived from data in human and animal studies and are reported for acute(< 14 days), intermediate (15-364 days), and chronic (> 365 days) exposures. MRLs arepublished in ATSDR Toxicological Profiles for specific chemicals.

The Occupational Safety and Health Administration's Permissible Exposure Limit (PEL) in air isan 8-hour, time-weighted average developed for the workplace. The level may be exceeded, butthe sum of the exposure levels averaged over 8 hours must not exceed the limit. The NationalInstitute for Occupational Safety and Health recommends exposure limits (RELs) for theworkplace. RELs are based on time-weighted average (TWA) concentrations for up to a 10-hourworkday during a 40-hour work week.

EPA's Reference Dose (RfD) and Reference Concentration (RfC) are estimates of the dailyexposure to a contaminant unlikely to cause adverse health effects. RfDs and RfCs do notconsider cancer.

The Clean Air Act of 1990 established National Ambient Air Quality Standards (NAAQS) for sixcriteria pollutants. Concentrations exceeding NAAQS in ambient air may endanger public health.

EPA classifies the carcinogenic potential of contaminants using the weight of evidence oftoxicological data. The Agency has established five classes of carcinogenicity:

A.    human carcinogen,
B1 and B2.    probable human carcinogen,
C.    possible human carcinogen,
D.    not classifiable as to human carcinogenicity, and
E.    evidence of noncarcinogenicity in humans.

Further, the B1 classification is supported by sufficient human evidence. The B2 classification issupported by sufficient animal evidence, but insufficient human evidence.

References

  1. Agency for Toxic Substances and Disease Registry. Public Health Assessment Guidance Manual. Atlanta: ATSDR, March 1992.
  2. National Institute of Occupational Safety and Health. Pocket Guide to Chemical Hazards. Washington D.C.: Department of Health and Human Services, June 1990.

APPENDIX D - RESPONSES TO PUBLIC COMMENTS

RESPONSES TO PUBLIC COMMENTS

ATSDR received many comments on the Public Release of this Public Health Assessment. Several of the comments have been addressed by making changes or additions in the publichealth assessment text or tables. Other issues that would be better answered by anotheragency such as EPA have been referred. The remaining questions and comments have beenaddressed by ATSDR separately in this Appendix. Responses by ATSDR are indicated initalics.

Comments are addressed using the following outline:

I. COMMENTS REGARDING CONCLUSIONS OF THIS PUBLIC HEALTHASSESSMENT

  1. GENERAL COMMENTS
  2. EPA LEAD GUIDELINES

II. HEALTH EFFECT ISSUES

  1. GENERAL
  2. LEAD EXPOSURE
  3. OTHER

III. COMPETING INTERESTS

  1. LEAD DISCUSSION
  2. ASBESTOS DISCUSSIONS
  3. OTHER

IV. RATIONALE FOR CONDUCTING PUBLIC HEALTH ASSESSMENTS

V. OTHER COMMENTS


I. COMMENTS REGARDING CONCLUSIONS OF THIS PUBLIC HEALTHASSESSMENT

Several comments dispute whether the Phelps Dodge site presented a public health hazard tothe Douglas and Aqua Prieta community. For a site to be considered a public health hazard,two elements must be present. 1) Evidence exists that exposures have occurred, are occurring,or likely to occur in the future. It is our opinion that exposures have occurred viacontaminated soil and ambient air. 2) The estimated exposures are to a substance orsubstances at concentrations in the environment that, upon long-term exposures (greater than1 year), can cause adverse health effects to any segment of the receptor population. It is ouropinion that levels of lead in surface soil was (and may still be) in sufficient amounts whilethe plant was operating to present a health risk for long-term exposure for children. Also,levels of PM10 and sulfur dioxide in air were in sufficient amounts to present a health risk forlong-term exposure. With these two criteria met, it is our opinion that the site posed a publichealth hazard.

It should be noted that the purpose of describing the public health category of a site is todetermine the most appropriate health activities to protect public health. In this case, ATSDRrecommended lead poisoning prevention activities for the community, local health careproviders, and the state health department.

A. GENERAL COMMENTS

1)    Phelps Dodge strenuously opposes the conclusions of the assessment...the only remedy is for the ATSDR to reject the document in its entirety by issuing a statement renouncing its conclusions. Anything less will constitute approval of an Assessment which makes mockery of the scientific process.

    As stated above, it is our opinion that this site meets the criteria for designation as a public health hazard. We have no plans for changing the conclusions; they are completely consistent with the public health assessment process and guidelines.

2)    Given the content of the report....the conclusion is unwarranted. There is nodemonstration...that the alleged elevated soil lead levels are a hazard or that they arederived...from the Douglas Reduction Works (DRW)...nor is there any information...to concludethat learning impairment existed as a problem in Douglas children.

    As stated above, it is our opinion that the levels of lead in off-site soil were and may still be ahealth hazard, and that the smelter, while operational, contributed to lead contamination offsite. Determining whether health effects (such as learning impairment) are directly attributableto exposures is not an essential criteria in determining whether or not a site is a public healthhazard. As stated above, the possibility for an adverse health effect is the criteria needed. Thepotential for soil exposure to contribute to elevated blood lead levels in Douglas' children is the reason werecommended lead poisoning prevention activities.

3)    The existing DRW site does not present a public health hazard.

    We are most concerned about off-site contamination that happened while the smelter wasoperational. Now that the smelter is gone, the potential for the site to be a source of off-sitesurface soil and ambient air contamination is reduced. Investigations are ongoing to assess thepotential for groundwater contamination. Also, EPA is also investigating off-site surface soilcontamination that may still persist. Of course, the smelter itself no longer presents a publichealth hazard, since it no longer exists.

4)    There is no evidence provided in this report that 1) there were excessive emissions, 2) thatthose emissions reached the citizens of Douglas, or 3) that other conditions did not totallyovershadow any contribution of contaminants from the DRW site.

    It is ATSDR's opinion that exposures to emissions from the smelter did happen, and that thoseexposures to soil and air contamination were at concentrations that could result in health effects. It is based on this reasoning that we deemed the site a public health hazard and proceeded withpublic health activities, focusing on lead poisoning prevention.

B. EPA LEAD GUIDELINES There was disagreement among commenters as to what the EPA Guidelines are for lead levels insoil, and whether those guidelines support or refute ATSDR's conclusions. The most recent EPAguidelines recommend:

"...400 ppm soil lead as a screening level for lead in soil for residential scenarios. Residential areas with soil lead below 400 ppm generally require no further action. However, in some special situations, further study is warranted below the screening level. For example...areas of higher than expected human exposure [is a] situation that could require further study."
Levels in Pirtleville averaged just under 400 ppm, with many samples exceeding 400 ppm asfound in 1985. EPA also found levels exceeding 400 ppm in 1989. In addition, it is our opinionthat conditions in Douglas, including little or no grass cover, unpaved roads, and a dry climate,may result in higher than usual human exposures to soil. Therefore, we believe that EPA'sguidance supports our conclusions that lead concentrations in residential soils are a publichealth hazard, and lead poisoning prevention activities are warranted.

5)    Based on 1989 EPA Sampling Data, soil lead levels in the Douglas Area do not pose a public health hazard.

    EPA only took seven soil samples, which makes it difficult to make any conclusions about overall off-site soil conditions. However, as noted above, levels did exceed the guidance value of 400 ppm.

6)    EPA Guidance on health protective soil lead levels refute the authors contention that current soil lead levels create a public health hazard...numerous studies...refute the authors contention.

    It is our opinion that EPA Guidance does not refute our conclusion, in fact, their guidance is supportive. See discussion above.

7)    Authors do not choose to refer to the current EPA guideline for residential soil lead levels, namely 500 mg/kg. The levels in Douglas generally appear to be below this level.

    The new EPA Guidance has been added to the Public Health Assessment. Many soil lead levels are above EPA Guidelines. The guidance value is 400 mg/kg, not 500 mg/kg.

II. HEALTH EFFECTS ISSUES

To determine whether we think health effects might be expected from a given exposure, wefirst consider whether people came into contact with contaminants. If they have, then weconsider whether they could have absorbed (by breathing, swallowing, or skin contact) a highenough dose of the contaminant to cause health effects. We strive to characterize exposuresand possible health implications as accurately as possible. However, complete data are oftennot available, and in that event, exposure assumptions are conservative. This means we tendto make our conclusions based on prudent public health practice rather than anunderestimate of the hazard to human health. This ensures that we will make decisions thatare highly protective of public health.

A. GENERAL

8)    [Inappropriate data presentation on Tables] Reporting maximum levels without providing ranges, numbers of samples, standard deviations, or other indications of the data variability is very misleading.

    Please note that means are provided on Tables 1B and 4 in Appendix B and in Figures 2, 3, and 4 in Appendix A. Data variability and numbers of samples are discussed in the text as well, in the Environmental Contamination and Other Hazards Section, and in the Exposure Pathways Section. Maximums are presented and discussed for public health purposes, please see note above.

9)    The data presented in the tables are biased because only the maximum concentration measured from a single sample is reported....mean or median concentrations resulting from analyses of all samples should be reported.

    Please see the above response.

10)    I have never known anyone who was medically impaired by the smelter emissions (past the annoyance stage). I do know doctors who state that they have never treated anyone who was injured by the smelter smoke.

    The public health assessment process dictates that, if a potential for a health hazard exists, protective actions need to be taken. The purpose of a public health assessment is not to determine whether people's health were impacted by smelter smoke or contamination. We determine if the potential exists. In this case, we believe that elevated levels of contamination in off-site soil and air were a public health hazard, and actions, such as lead poisoning prevention, needed to be implemented.

B. LEAD EXPOSURE

Some of the comments concerned the reported blood lead levels, especially those from 1985. There may have been some quality control issues with the results, and estimates indicate that thelevels may have been about 33 % lower than reported (averaging about 9.8 µg/dL instead of13.7 µg/dL). Some commenters argue that, since this average is below the CDC guideline of 10µg/dL, there is no need for lead poisoning prevention activities in Douglas. However, the exactwording of CDC's guidelines is as follows:

"If many children in the community have blood lead levels 10 µg/dL, community interventions(primary prevention activities) should be considered by appropriate agencies."
Whether the average blood lead levels in Douglas were exactly 9.8 µg/dL, around 10 µg/dL, or 13.7 µg/dL, there are still many children with blood lead levels 10 µg/dL. Therefore, community interventions to prevent lead poisoning in children, are an appropriate recommendation, and a need for the Douglas community.

11)    The mean blood lead level of children tested in Douglas in 1985 was below CDC's recommended safe level of 10 µg/dL.

    The estimated mean was calculated at about 10 µg/dL, not measured. Again, whether the mean was 10 µg/dL or 13.7 µg/dL, CDC Guidelines dictate community interventions.

12)    [CDC blood lead guidelines and the lack of comment concerning current controversies]..clearly there has been much discussion and revelation concerning the work by Needleman and his collaborators. Recent investigations strongly support the fact that these studies overestimated risk.

    CDC's Guidelines are not solely based on Dr. Needleman's work (which has withstood extensive review) . The concern about adverse effects on central nervous system functioning at blood lead levels as low as 10 µg/dL is based on a large number of rigorous epidemiologic and experimental studies. Evaluation of 24 major studies provides strong support for the belief that children's IQ scores are inversely related to lead burden.

13)    Table 8 shows that mean levels 0-2 miles from the stack were 13.7 µg/dL compared to 12.7 µg/dL at 2-5 miles from the stack...the authors seem to rely here on the raw data without any statistical verification of significance.

    Both averages were over the CDC guideline value of 10 µg/dL and indicated the need for publichealth intervention (see opening comments). Determining public health needs is the purpose ofthis assessment, and this data helped determine the need for lead poisoning prevention activitiesfor Douglas. This recommendation would have been made regardless of whether or not 13.7was significantly different from 12.7.

C. OTHER

14)    It should be a high concern to design a comprehensible health screening for arsenic and cadmium, but the study does not conclude that these are contaminants worthy of monitoring in the human body.

    For health screening of heavy metals such as arsenic and chromium to be meaningful, exposures must be current. Biomonitoring is not useful in determining the extent of past exposures, because the metals are no longer present in blood or urine. There is currently no evidence that excessive exposures to arsenic and cadmium are happening. If environmental monitoring indicates that exposures are ongoing, then ATSDR will consider a recommendation for health screenings for arsenic and cadmium.

15) Past air emissions from the DRW site have not increased the risk of cancer or disease in the local population.

    It is our opinion that past air emissions from the smelter were a public health hazard for the local population. Air monitoring in the residential area indicated that exposures to sulfur dioxide, lead, and inhalable particulate were occurring, and at levels that, on a long-term basis, may cause adverse health effects.

III. COMPETING INTERESTS

Several commenters believe that the public health assessment was skewed and biased towards focusing blame on the former smelter. The major concern of a health assessment is to use existing data to analyze whether a health threat exists and, if so, to determine what actions need to be taken to protect the health of the public. Determining the source of contamination is important if it will affect our recommendations about how to reduce or stop exposure, but establishing the responsibility or the degree of responsibility for contamination is not part of ATSDR's mandate. When investigating a site, we consider the public health effect of any contamination we identify, not just contamination that can be directly linked to the site and only the site.

A. LEAD DISCUSSIONS

16)    Emissions from vehicles using leaded gasoline in Mexico, and other sources of lead,contribute wholly or in part to soil/lead and blood/lead levels in the Douglas area...the conclusionblindly assumes that past operations at the DRW site were the sole cause of the allegedlyincreased soil lead levels in the area.

    We believe that our conclusions do not make this assumption. Based on air emissions data andon-site and off-site soil monitoring, we do conclude that the smelter probably did contribute tolead contamination in Douglas. The percentage of the smelter's contribution to soilcontamination is not discussed and is beyond the scope of the public health assessment (seediscussion above).

17)    Tone of the report and assumption that most of the community lead is from DRW.

    The focus of this public health assessment is the former smelter, as requested in the petitionfrom community members. However, we do discuss other sources of lead contamination withinthe Public Health Assessment, please see the Pathway Analysis Section. Again, it is not ourmandate to assume or estimate the degree to which one source may have contributed to off-sitecontamination.

18)    Are lead and arsenic separable in the analysis...If the lead and arsenic are released from stack emissions simultaneously, and if wind erosion carries soil-contaminated lead to Douglas, why would these metals not be found elevated together?

    The maximum release of lead from the stack was 0.0118 mg/m3, while the maximum release ofarsenic from the stack was 0.000121 mg/m3. Different emission amounts may result in differentconcentrations in surrounding soil. However, as stated above, establishing the degree ofresponsibility for contamination is not part of ATSDR's mandate. Our goal is to use existingdata, analyze whether a health threat exists, and implement actions to protect public health.

19)    Approach of the authors was decidedly designed to emphasize the possible contribution of DRW....the authors minimized many sources [of lead exposure] and neglected others totally.

    Again, the petition and community health officials specifically cited the Phelps DodgeReduction Works. Other sources were discussed, and their identification was essential inconducting appropriate community and health profession education.

20)    The authors are misleading in asserting that DRW is the only known industrial source of lead pollution in a section that also mentions gasoline and auto exhaust.

    By industrial source, we mean a stationary industrial site. There were no industrial releasesreported on the Toxic Release Inventory Database for Douglas from years 1987-1990. Werecognize that gasoline exhaust is another source of lead pollution for Douglas and Aqua Prieta. Please note the discussion in the "Exposure Pathway Analyses" section.

21)    The authors relied heavily on a case report about a child with a blood lead level of 30 µg/dL ...there was a note that there was chipped, leaded paint on outdoor furniture.

    This information has been added, as well as additional blood lead monitoring data from 1991 until 1993. Please see the Health Outcome Data Evaluation Section.

22)    The report seems to imply that the only source of leaded gasoline is Mexico.

    We recognize that leaded gasoline is also still sold in some gas stations in Arizona. This information has been added to the public health assessment.

B. ASBESTOS DISCUSSIONS

Several of the comments debate the discussions regarding the workers that alleged occupationalasbestos exposure during demolition activities. The purpose of including this discussion in thepublic health assessment was to provide public health guidance for those workers, in case therehad been improper respiratory protection months before the OSHA inspection. If protection hadbeen adequate during those months, this section may be disregarded. If not, then we hope thatthe information addressing their concerns is helpful, and that they consult their physicians forappropriate follow up for asbestos exposure.

23)    [In regards to asbestos exposure] The document ignores expert agency reviews which were contemporaneous.

    We do not believe that this Public Health Assessment ignores expert reviews. Please note that the OSHA inspection report is discussed in the Environmental Contamination and Other Hazards Section, and is cited as reference number 5.

24)    [In regards to asbestos exposure] The authors do not identify whether [elevated levels of asbestos] were found during the time that the complainant stated he was not wearing a respirator, or whether it occurred when he was undisputedly wearing approved respiratory protection.

    Elevated levels were found on both occasions. See the discussion in the Environmental Contamination and Other Hazards Section.

25)    The authors do not consider the accuracy of the petitioner's claim.

    The purpose of including a petitioner's concern is to address his or her health concerns regarding possible asbestos exposure.

26)    Because state agencies determined that no improper asbestos exposure occurred, the authors of the assessment had no basis for accepting this petition...or for concluding that an asbestos exposure pathway ever existed.

    We did not conclude that an exposure pathway for asbestos existed, just that it may have been possible. Again, the asbestos discussion was included to address worker health concerns.

C. OTHER

25)    The arsenic data: other possible conclusions and author bias. The fact that authors "expected" high levels of arsenic demonstrates their bias and lack of objectivity.

    The assumption is based on typical ambient arsenic levels around copper smelters as stated in the Hazardous Substance Data Base.

26)    There are many forms of arsenic in the environment, including arsenic species in foods. If the samples were not tested for inorganic arsenic, their relevance would be highly questionable.

    We agree that there are many forms of arsenic in the environment, however, note that we did not conclude that the concentrations of arsenic in the environment in Douglas presented a public health hazard.

27)    There is no evidence that past or present emissions from the DRW or any other source threaten to contaminate groundwater.

    It is our opinion that there is not enough information at this time to determine whether or not the slight elevations of arsenic and lead in groundwater are site-related, naturally occurring, or are related to some other source.

IV. RATIONALE FOR CONDUCTING A PUBLIC HEALTH ASSESSMENT

Several comments regard ATSDR's decision to conduct a public health assessment for this site. The wording in the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) reads as follows:

"The Administrator of ATSDR may perform health assessments for releases or facilities where individual persons or licensed physicians provide information that individuals have been exposed to a hazardous substance, for which the probable source of such exposure is a release. In addition to other methods (formal or informal) of providing such information, such individual persons or licensed physicians may submit a petition to the Administrator of ATSDR providing such information and requesting a health assessment."
It is ATSDR's opinion that the petition and other requests for an ATSDR health assessment at the Phelps Dodge site met the criteria for conducting a health assessment according to CERCLA.

28)    Phelps Dodge also questions the ATSDR's authority to undertake the Assessment at all....even if ATSDR's decision to perform the Assessment in response to the former employee's petition was proper, the scope of the Assessment has gone far beyond the on-site exposure to asbestos which was the basis for that petition.

    ATSDR received other requests and concerns from community members and officials regarding past air and soil contamination, in addition to the petitioners request. It is our opinion that the public health assessment complies with Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) as amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA). CERCLA states under section 110 subsection 6(F) that "the term 'health assessment' shall include preliminary assessments of potential risk to human health posed by individual sites and facilities, based on such factors as the nature and extent of contamination, the existence of potential pathways of human exposure (including ground or surface water contamination, air emission, and food chain contamination), the size and potential susceptibility of the community within the likely pathways of exposure, the comparison of expected human exposure levels to the short-term and long-term health effects associated with identified hazardous substances and any available recommended exposure or tolerance limits for such hazardous substances, and the comparison of existing morbidity and mortality data on diseases that may be associated with the observed levels of exposure" (49).

29)    I am not aware that ATSDR is the proper agency to handle workplace requests. It is my understanding that these issues are for OSHA and perhaps NIOSH to address.

    OSHA was involved with the workplace asbestos-exposure issue. See the Environmental Contamination and Other Hazards Section. Also, note that ATSDR may respond to "any individual" as stated in CERCLA.

V. OTHER COMMENTS

30)    The DRW site is not now, and never has been, the site of a municipal landfill. The City of Douglas purchased the land from Phelps Dodge to operate a landfill, but that land is not on the DRW site.

    Sentence clarified to show that the landfill is on former DRW property.

31)    The northern portion of the facility has an eight-foot high, chain-link fence.

    Sentence added on page 5.

32)    The authors claim that while it was flowing, elevated levels of heavy metals were detected in Whitewater Draw. ADEQ had admitted that proper sampling protocol was not followed in gathering its Whitewater Draw surface water samples.

    ATSDR did not conclude that Whitewater Draw presented a public health hazard. It is unlikely that additional QA/QC data from ADEQ would change that conclusion.

33)    The authors state that discharges made to Whitewater Draw from the DRW site were "not permitted by EPA"...the intimation in this choice of language is that these discharges were illegal.

    The reason that a permit was not needed is explained on both page 4 and 8 where this statement occurs; i.e. that a court decision determined that Whitewater Draw was not a "navigable water of the United States".

34)    Whitewater Draw actually flows on the eastern border of the DRW site.

    Sentence on page 8 corrected.

35)    Since the closure of the smelter, literally, hundreds of yucca plants, all north of the smelter, in the old emissions belt, are now dying and dead. Before closure, one rarely saw a dead yucca, maybe one in a thousand, due to old age.

    ATSDR will pass this information on to EPA.

36)    Report title: There was no health assessment conducted in this study...no directed examinations of residents with a standard protocol was utilized for this "study".

    A health assessment is not meant to be a study. It is the first step in evaluating the health of communities impacted by a release of a hazardous substance. A health assessment considers the community as an aggregate, and its exposure to a hazardous substance release. The legal definition of a health assessment as stated in CERCLA is as follows:
    "..the term 'health assessment' shall include preliminary assessments of the potential risk to human health posed by individual sites and facilities, based on such factors as the nature and extent of contamination, the existence of potential pathways of human exposure, the size and potential susceptibility of the community within the likely pathways of exposure, the comparison of expected human exposure levels to the short-term and long-term health effects associated with identified hazardous substances and any available recommended exposure or tolerance limits for such hazardous substances, and the comparison of existing morbidity and mortality data .."

    It is our opinion that the Phelps Dodge Public Health Assessment meets this definition. CERCLA goes on to state that an epidemiological study (such as suggested in the above comment) may be considered as a subsequent public health activity.

37)    Do "zero" levels exist?

    This statement refers to the Ambient Air Pathway discussion, "Background levels of arsenic in rural parts of the United States ranged from 0.0 to 0.0001 mg/m3". This is a direct quote from the Hazardous Substance Database. The "zero" level probably means that the air monitoring instruments could not detect arsenic.

38)    Significant figures and conventions to rounding numbers. [For instance, in regards to the discussion of ambient air concentrations of arsenic] The statement that 0.000121 is greater than 0.0001 mg/m3 is ignorant...wrong, inflammatory, and likely to produce undue anxiety among the community.

    Whether 0.000121 is slightly above 0.0001 or essentially equal will not impact ATSDR's conclusion that, based on the air monitoring data, arsenic did not pose a public health hazard for residents. Because of the qualitative nature of assessments, rounding measured levels to significant figures would have no influence on the conclusions of this document.

39)    I have difficulty with some low-level elevations above a CDC-guideline being listed as a "Health Status" in the conclusions.

    "Health Status" has been changed to "Health Outcome Data".

40)    Contradictory reasoning: that smelting increased during daylight hours when smoke tendedto travel to Mexico. Smelting was generally increased in the evening and at night when airinversion patterns reversed and smoke tended to stay above the ground and/or flow into Mexico.

    Sentence corrected.

41)    With 200 acres of slag over nearly 90 years from two smelters, the contaminant levels in the waste will vary enormously. This should be noted in the report.

    We have no data to indicate that contaminant levels in the slag pile vary enormously, but we acknowledge that variability is possible. However, note that the public health assessment concludes that human exposure to slag (via ingestion) is a very unlikely human exposure pathway.

42)    There is an obvious need to expand leachability and toxicity testing into Mexico [because of groundwater monitoring results in both Agua Prieta and Douglas].

    ATSDR has recommended ongoing groundwater monitoring to ensure that levels of heavy metals in Douglas' drinking water are within MCLs, and have worked with the Pan American Health Organization and Mexican Federal Health authorities to encourage Agua Prieta health officials to conduct similar activities. EPA will conduct investigations to determine whether the site is eligible for listing on the National Priorities List under CERCLA. We will pass this concern on to EPA.

43)    We would like it noted that after crossing the border, Whitewater Draw becomes Rio Agua Prieta, a perennial body of water that is vulnerable to any contamination generated by the Phelps Dodge site.

    Noted.

44)    We take issue with ATSDR'S health outcome (table 9) that describes the area of concern as having a population of 12,822 when the actual population impacted probably exceeds 90,000 on both sides of the border.

    The public health assessment was revised to include this information.

45)    Instead of discussing this important fact [that benzene and arsenic have been within background levels], they are discussed and revealed in a circuitous manner.

    The public health implications of benzene and arsenic levels are discussed within the framework of the Public Health Assessment Guidelines.


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