PUBLIC HEALTH ASSESSMENT
NATIONAL ZINC COMPANY
BARTLESVILLE, WASHINGTON COUNTY, OKLAHOMA
Appendix 1
Figure 1
Appendix 1, Figure 1 - Map of the Proposed National Zinc
Company National Priorities List Site, Bartlesville, OK
Appendix 2
Health Comparison Values
Health comparison values for the Agency for Toxic Substances and Disease Registry (ATSDR) public health assessments are contaminant concentrations that are found in specific media (air, soil, and water) and that are used to select contaminants for further evaluation. The values provide guidelines that are used to estimate a dose at which health effects might be observed. The health comparison values were developed by using the most conservative assumptions (i.e., worse case). For example, soil health comparison values are developed for children who exhibit pica behavior. Soil ingestion in pica children greatly exceeds the soil ingestion rate for the normal population. Health comparison values used in the Environmental Contamination and Other Hazards and the Public Health Implications sections of this public health assessment are listed and described below.
Cancer Risk Evaluation Guides (CREGs) are estimated contaminant concentrations that would be expected to cause no more than one excess cancer in a million (10E-6) persons exposed over a lifetime. CREGs are calculated from EPA's cancer slope factors.
Environmental Media Evaluation Guides (EMEGs) are based on ATSDR's minimal risk levels (MRLs) and factor in body weight and ingestion or inhalation rates. Reference Dose Media Evaluation Guides (RMEGs) are the same as EMEGs, except that they are based on the U.S. Environmental Protection Agency (EPA) reference doses (RfDs).
An MRL is an estimate of daily human exposure to a chemical (in mg/kg/day) that is likely to be without an appreciable risk of deleterious effects (noncarcinogenic) over a specified duration of exposure. MRLs are based on human and animal studies and are reported in the ATSDR Toxicological Profiles for acute (< 14 days), intermediate (15-365 days), and chronic (> 365 days) exposures.
EPA's RfD is an estimate of the daily exposure to a contaminant that is unlikely to cause adverse
health effects. However, RfDs do not consider carcinogenic effects.
Appendix 3 - Environmental Exposure Pathways
Tables 1 and 2
| Appendix 3, Table 1 - Completed Environmental Exposure Pathways at the Proposed National Zinc Company National Priorities List Site | ||||||
| Pathway Name |
Point of Exposure |
Route of Exposure |
Exposed Population |
Time of Exposure |
Contaminants of Concern |
Estimated Exposed Population |
| Surface Soil | The Smelters and Surrounding Residential Areas |
Ingestion Inhalation Skin Contact |
Smelter Workers and Residents near the Smelter |
Past Present Future |
Cadmium Lead Zinc |
More Than 5,000 |
| Air | The Smelters and Surrounding Residential Areas |
Inhalation Ingestion Skin Contact |
Smelter Workers and Residents near the Smelter |
Past | Cadmium Lead Zinc Sulfuric Acid |
More Than 5,000 |
Appendix 4 - Comparison of Estimated Exposure Doses
to Health Guidelines
Calculation of Exposure Doses for Soil Ingestion
The exposure doses for soil ingestion were calculated in the following manner. The maximum concentration for a contaminant was
multiplied by the soil ingestion rate for adults, 0.0001 Kg/day; children, 0.0002 Kg/day; or pica children, 0.005 Kg/day. (The habit of
ingesting large amounts of soil is called pica.) This product was divided by the average weight for an adult, 70 Kg (154 pounds) or
for a child, 10 Kg (22 pounds). Those calculations assume that there is frequent daily exposure to soil contaminated at the maximum
level. A qualitative summary of these results can be found in the table above.
Appendix 5 - Response to Comments Received during the Public
Comment Period for the National Zinc
Company Public Health Assessment
The National Zinc Company (NZC) Public Health Assessment was available for public review and comment from September 21, 1994, through November 20, 1994. The Public Comment Period was announced in the Tulsa World and the Bartlesville Examiner-Enterprise. Copies of the public health assessment were made available for review at the Westside Community Center and the Bartlesville Public Library. In addition, the public health assessment was sent to nine persons or organizations. On October 13, 1994, the Agency for Toxic Substances and Disease Registry (ATSDR) held a Public Meeting at the Westside Community Center. The Public Meeting was arranged so that the public could discuss the findings of the NZC Public Health Assessment with ATSDR and to permit the public to provide ATSDR with any comments.
During the Public Comment Period, ATSDR received comments from two individuals, two
consulting firms, the Oklahoma State Department of Health (OSDH), and the Oklahoma
Department of Environmental Quality (ODEQ). Comments and ATSDR responses are
summarized below. The comment letters can be requested from ATSDR through the Freedom
of Information Act.
| Comment: | I would like to request an additional 30 days beyond the October 20, 1994, date to
make a public comment regarding the Health Assessment of NZC. |
| Response: | ATSDR extended the Public Comment Period for the NZC Public Health
Assessment until November 20, 1994. |
| Comment: | Since the Resource Conservation and Recovery Act (RCRA) and Superfund are
separate divisions, but both involved in cleanup recommendations and activities,
there needs to be some cooperation within U.S. Environmental Protection Agency
(EPA) to co-ordinate (or at least interpret for the public) what their current and
future recommendations will be for both divisions. Citizens should have some
input on RCRA recommendations as they do with Superfund. |
| Response: | Because ATSDR is an independent non-regulatory agency separate from the EPA
and the ODEQ, we can not direct these agencies to coordinate their activities.
However, ATSDR will submit your comment and concern to the appropriate
individuals within EPA and ODEQ. |
| Comment: | Footnote 5 on page 29 should be revised to read as follows: "The Maternal and
Child Health Service, Oklahoma State Department of Health (OSDH), conducted
the blood lead testing in collaboration with the OSDH environmental unit. The
OSDH environmental unit became a part of the Oklahoma Department of
Environmental Quality in 1993. This unit continues to oversee the overall
community activities." |
| Response: | The public health assessment has been revised accordingly. |
| Comment: | The response to question 4, "Is Multiple Sclerosis (MS) caused by lead and/or
cadmium?", goes into detail that is not pertinent to the issue being discussed.
OSDH would like to recommend that a significant portion of this response be
deleted. |
| Response: | The public health assessment has been revised as recommended. |
| Comment: | Change the last sentence of the first full paragraph on page 33 to read as follows:
|
| Response: | The public health assessment has been revised as recommended. |
| Comment: | Summary, paragraph three, line eight. The ODEQ believes that the use of
"National Zinc Site" or " historical smelter operations" should be utilized to avoid
confusion as to the current status of the Zinc Corporation of America facility
which is not included in the National Zinc Company CERCLIS site. |
| Response: | The public health assessment has been revised to avoid the confusion. |
| Comment: | Page 3, paragraph five, line four. The use of the word "safe" would appear to
inappropriate; we would suggest substitution by "acceptable." |
| Response: | Based upon current scientific information, the blood lead levels detected in the
Bartlesville children were above levels which are known not to be safe (i.e.,
adverse health effects could occur) or acceptable by current guidelines. ATSDR
prefers the term "safe" because it not only indicates that health officials have
determined that these levels are not acceptable but that adverse health effects
could occur. |
| Comment: | Page 5, paragraph two. Dr. Edd Rhoades, chief of Pediatrics, Oklahoma State
Department of Health conducted medical education regarding lead exposure
during 1992. |
| Response: | This information has been added to the public health assessment. Thank you for
providing it to ATSDR. |
| Comment: | Page 5, paragraph three. Discussion of actions regarding the "National Zinc Site"
under the Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA) and actions regarding the Zinc Corporation of America facility
under RCRA should be separated to avoid confusion. |
| Response: | The public health assessment has been revised as recommended. |
| Comment: | Page 8, paragraph two, last sentence. Appendix 2 contains no listing of the health
comparison values; these appear in Tables 1, 2, and 3. |
| Response: | The public health assessment has been revised to avoid the confusion. |
| Comment: | Page 21, paragraph one. The value being referred to as "exposure dose" is in
actuality an "exposure level" or "estimated chronic intake" rather than a dose.
The use of the term "dose" is misleading. |
| Response: | The use of the term "exposure dose" is being used in accordance with the ATSDR
Public Health Assessment Guidance Manual. |
| Comment: | Page 21, paragraph three. The statement that there are no health guidelines for
exposure to lead in soil is inaccurate. EPA and ODEQ have set action guidelines
for interpretation of lead concentrations in soil of 500 ppm in residential areas.
The underlying basis for this guideline is the protection of human health. |
| Response: | ATSDR has not been able to establish a minimal risk level (MRL) for lead
because a threshold has not yet been defined for the most sensitive effects of lead
(i.e., neurotoxicity). EPA has not been able to establish a reference dose (RfD)
for the same reason. The action level discussed by the commentator was
established to help site investigators determine whether additional soil sampling
should be conducted at a site. The guidelines do not establish any health
guidance and should not be used to predict health outcomes. |
| Comment: | Page 22, paragraph one under a. Cadmium, Soil. The soil concentration
presented as acceptable (non-pica children) for cadmium, 375 parts per million
(ppm), is considerably above the risk based level proposed for residential areas by
the ODEQ in the Proposed Plan (100 ppm) which is criticized by ATSDR in their
comments on the ODEQ Proposed Plan, dated October 12, 1994. It would appear
that ATSDR is inconsistent in what is considered to be an acceptable level of
cadmium in soil. |
| Response: | In the latter part of the paragraph cited by the commentator, ATSDR states:
In ATSDR's comments to ODEQ concerning the Proposed Plan, ATSDR did not
recommend a cleanup level. ATSDR only provided ODEQ with it's opinion on
what factors should be considered and evaluated when developing a cleanup
level. Therefore, ATSDR does not believe it is being inconsistent. |
| Comment: | Page 23, paragraph one (Air) and paragraph five (Risk of Cancer). The
maximum air concentration (0.61 micrograms of cadmium per cubic meter of air
[µg/m3]) cited was determined to be an invalid sample by EPA and ODEQ.
Therefore, the use of an invalid sample point to determine risk of cancer is
inappropriate. We would suggest the use of the average air value or presentation
of risk by a range based on the range of concentrations measured in the area. |
| Response: | The public health assessment has been revised to correct this misunderstanding
and to clarify the agency's opinion |
| Comment: | Page 23, paragraph five (Risk of Cancer). The structure of the paragraph is
misleading. The reference to the cadmium smelter worker study which identified
a two fold increase in the rate of lung cancer could be read to refer to the
historical smelter operation in Bartlesville. This not the case. The paragraph
should be rewritten to clarify that the data from the study are not reflective of the
concentrations associated with the National Zinc site. |
| Response: | The public health assessment has been revised to avoid the confusion. |
| Comment: | Page 24, c. Sulfuric Acid. The discussion regarding the fact that current
exposures to sulfuric acid are not present in the area and that health consequences
related to the 1977 releases would not be occurring in the present needs to be
strengthened here and in the Summary and Conclusions Sections. |
| Response: | This issue was also raised by another commentator. The public health assessment
has been revised as recommended. |
| Comment: | Information concerning the 1977 through 1979 Environmental Consultants
Laboratory blood lead study was not included in the public health assessment. |
| Response: | This information has been added to the public health assessment (i.e.,
Background and Review of Blood Contaminant Data sections). Thank you for
bringing this information to the attention of the Agency. |
| Comment: | Page 32, response to questions 4. The inclusion of the material relating multiple
sclerosis and latitude is misleading. It is not clear what significance this material
has to the question that was posed and the situation in Bartlesville. |
| Response: | This issue was also raised by another commentator. The public health assessment
has been revised as recommended. |
| Comment: | Page 34, A. Public Health Actions Taken. The commentator provided ATSDR
with information which should be included in this section. |
| Response: | ATSDR appreciates receiving this information and has included it in the
appropriate sections of the public health assessment. |
| Comment: | The inclusion of zinc as a contaminant of concern is problematic. In the baseline
risk assessment prepared for EPA by CH2M Hill, the Remedial
Investigation/Feasibility Study (RI/FS) and the proposed plan have all indicated
that the contaminants of concern at the site included lead, cadmium, and arsenic.
Zinc has been determined to be of significance as an ecological concern. |
| Response: | In accordance with the ATSDR Public Health Assessment Guidance Manual
health comparison values are used to determine which contaminants should be
looked at more closely in the public health assessment. As stated in the
Environmental Contamination and Other Hazards section:
"A contaminant is selected for further evaluation if the contaminant concentration in a valid environmental sample exceeds comparison values. The presence of a contaminant on the lists in the tables of this section does not mean that either exposure to the contaminant or adverse health effects has occurred or will occur. Inclusion in the list indicates only that the potential for human exposures to the selected contaminants and the potential for adverse human health effects as a result of any exposures to the selected contaminants will be discussed in more detail in later sections of this Public Health Assessment." ATSDR evaluates the possible toxicological effects of zinc in the Toxicological
Evaluation section of the public health assessment. In that section, ATSDR states
that there is some possibility of noncarcinogenic health effects for children
exposed to zinc in residential soil. However, it is uncertain that these health
effects would occur because of the different zinc metabolism between adults and
children. |
| Comment: | ATSDR has failed to consider the off-site groundwater monitoring data that
indicate groundwater is not a potential exposure pathway. The commentator
provided ATSDR with copies of their investigation reports. |
| Response: | ATSDR appreciates receiving the off-site groundwater monitoring data. The data
will be included in the public health assessment and the conclusions and
recommendation will be changed as appropriate.
It should be noted that the investigation reports were submitted to EPA just
before and during the Public Comment Period for the NZC Public Health
Assessment. Therefore, this information was not available to ATSDR in order to
develop the public comment release public health assessment. |
| Comment: | Air monitoring data show that dust from the residue piles is not a threat to public
health. The commentator provided ATSDR with copies of their investigation
report. |
| Response: | ATSDR appreciates receiving the air monitoring data. The data will be included
in the public health assessment and the conclusions and recommendation will be
changed as appropriate.
It should be noted that the investigation reports were submitted to EPA just
before and during the Public Comment Period for the NZC Public Health
Assessment. Therefore, this information was not available to ATSDR in order to
develop the public comment release public health assessment. |
| Comment: | ATSDR has overestimated risk, casting doubt on it's conclusions and
recommendations. The commentator made eight specific points. |
| Response: | ATSDR does not believe it has overestimated the possible risk associated with the
NZC Site. ATSDR will respond to each of the commentators points. |
| Comment: | Point 1. An overly conservative target risk level for use in evaluating need for
remediation. |
| Response: | The target risk levels cited by the commentator are the health comparison values
in the public health assessment. In accordance with the ATSDR Public Health
Assessment Guidance Manual health comparison values are used to determine
which contaminants should be looked at more closely in the public health
assessment. As stated in the Environmental Contamination and Other Hazards
section:
"A contaminant is selected for further evaluation if the contaminant concentration in a valid environmental sample exceeds comparison values. The presence of a contaminant on the lists in the tables of this section does not mean that either exposure to the contaminant or adverse health effects has occurred or will occur. Inclusion in the list indicates only that the potential for human exposures to the selected contaminants and the potential for adverse human health effects as a result of any exposures to the selected contaminants will be discussed in more detail in later sections of this Public Health Assessment." ATSDR evaluates the possible toxicological effects for each of the contaminants selected (i.e., above health comparison values) in the Toxicological Evaluation section of the public health assessment. In this section, ATSDR discusses the possible health effects and the uncertainty of the toxicological information. The ATSDR Minimal Risk Levels (MRLs) and Cancer Risk Evaluation Guides (CREGs) used in this public health assessment come from the chemical specific ATSDR Toxicological Profile. Each Toxicological Profile is peer reviewed and released for public comment. Each Toxicological Profile describes how each MRL and CREG is developed. It is important to note that ATSDR did not base its conclusions and
recommendations solely on the toxicological information. The blood lead studies
have consistently shown that children living near the smelter have blood lead
levels above the Centers for Disease Control and Prevention guidelines. |
| Comment: | Point 2. A flawed RfD for zinc, especially as applied to infants and children. |
| Response: | ATSDR agrees that there is some uncertainty associated with the zinc RfD as it
applies to infants and children. In the toxicological section, ATSDR states that
there is some possibility of noncarcinogenic health effects for children exposed to
zinc in residential soil. However, ATSDR is uncertain whether these health
effects would occur because of the different zinc metabolism between adults and
children (page 24 of the public comment release public health assessment). |
| Comment: | Point 3. Use of a single maximum value for a metal in soil to estimate exposure. |
| Response: | ATSDR did not only use a single maximum value for estimating exposure. In the
Toxicological section, ATSDR indicates at what environmental soil concentration
exposures would exceed an ATSDR Minimal Risk Level (MRL) or EPA
Reference Dose (RfD). For example, on page 22 of the public comment release
public health assessment ATSDR states:
"Soil concentrations of cadmium of 375 mg/kg and greater result in exposure
doses for small children (10 kilograms [Kg]/22 lbs) that exceed the lowest
observed effect level in humans of 0.0075 milligrams of cadmium per kilogram
body weight per day (mg/kg/day). For small children who ingest large amounts
of soil (i.e., pica children), the lowest effects level is exceeded when the cadmium
level exceeds 15 mg/kg. Cadmium soil levels in the community around the Zinc
Corporation facility vary from 0.2 - 1,372 mg/kg." |
| Comment: | Point 4. The inclusion of the pica child to evaluate chronic effects. |
| Response: | In accordance with the ATSDR Public Health Assessment Guidance Manual, the
possible toxicological effects for all people living and working at a site, including
sub-populations (i.e., pica children), should be discussed in a public health
assessment. ATSDR agrees that there is some uncertainty as to how much and
how long a child ingests soil. As indicated in the response to sub-comment
number 3, even non-pica children may be exposed to cadmium in soil at levels of
public health concern. Therefore, ATSDR conclusions are not based solely on
the possible exposures to pica children. |
| Comment: | Point 5. Lack of consideration of the bioavailability of metals in soil. |
| Response: | Bioavailability of metals in soils is an issue that needs to be considered when
evaluating the toxicity of metals found in soils. However, bioavailability is
dependent upon site-specific conditions (e.g., chemical species of the soils and
metals, the nutritional status of the exposed population, etc.).
ATSDR is familiar with the site-specific bioavailability study conducted by PTI Environmental Services. However, this study does have some limitations. The primary limitation is that the rodent is not the best model for representing bioavailability in a child. The pig is thought to be a better animal model for metal bioavailability studies (Weis CP and Lavelle JM. Characteristics to consider when choosing an animal model for the study of lead bioavailability. Chemical Speciation and Bioavailability. 1991;3(3-4):113-119.). In addition, the regimen of introducing the contaminants with the feed may alter bioavailability. A child may ingest soil or dust on an empty stomach. This would result in more metal uptake. The animal model also does not represent a child or infant with poor nutrition, a possible situation at the NZC site. Therefore, ATSDR decided that there is not any good site-specific bioavailability data. Most of the toxicological studies cited by ATSDR reported the exposure dose
(dose in the feed) given to the animals. In addition, the epidemiologic worker
studies cited by ATSDR reported the environmental concentrations (exposure
doses) that the workers were exposed to. Given the uncertainty surrounding the
bioavailability of metals and the differences between animal and human metal
uptake, ATSDR compared the exposure dose of the animals and the exposure
dose of the workers in the epidemiologic studies to the exposure doses that the
people near the NZC site may experience. In addition, ATSDR relied upon the
result of the blood lead and blood cadmium studies. These studies indicate that
people near the site have higher blood lead and blood cadmium levels than people
farther away from the site. ATSDR came to its conclusions by using this weight
of evidence approach. |
| Comment: | Point 6. Lack of consideration of antagonistic interactions between cadmium and
zinc. |
| Response: | ATSDR has added a new sub-section to the public health assessment which
discusses the interaction between cadmium, lead, and zinc. The information is
based upon the ATSDR Toxicological Profiles for cadmium, lead, and zinc. |
| Comment: | Point 7. Failure to incorporate site-specific data on the transfer of metals from
soil to dust. Specifically, using the default values in the EPA Integrated Exposure
Uptake Biokinetic Model for lead in children (IEUBK). |
| Response: | ATSDR is very familiar with the IEUBK. ATSDR's believes that the IEUBK
should not be used to predict health outcomes. In addition, ATSDR believes that
the IEUBK should not be used as the sole basis for selecting the lead cleanup
level at this site or any other site. The IEUBK is not validated for all sites and
situation and does not take into account all of the health aspects needed to be
considered when trying to determine possible health outcomes or when selecting
a soil cleanup level. For example; the type and variation of soil cover within the
area, the nutritional status of the population within the area, and the possible
interactions between lead and the other site-related contaminants may all
influence exposure and need to be considered and evaluated. |
| Comment: | Point 8. No consideration of results from recent studies demonstrating a minimal,
if any, impact on blood lead levels after soil removal. The commentator
specifically cited the EPA's Three-City Lead study. |
| Response: | ATSDR is familiar with the Three-City Lead study. Although the study was very
large and well conducted, it does have some limitations. The main limitation is
the study did not determine where the study children played and spent their time
outside. Therefore, the study may have a significant exposure bias. ATSDR
believes the Three-City Lead study is a significant step in understanding the
relationship between lead poisoning and the sources of lead. However, additional
studies are needed to confirm the Three-City Lead study results.
The results of the Three-City Lead study can not be directly related to the
situation in Bartlesville. As discussed above, various site-specific factors
influence the bioavailability of lead and other metals. The specific situations at
the three cities in the EPA study (Baltimore, Boston, and Cincinnati) are different
from Bartlesville (e.g., the NZC smelter). |
| Comment: | The draft public health assessment is irrelevant and misleading. The draft public
health assessment was issued out of sequence to the RI/FS report. Its' conclusions
conflict with those in the Proposed Plan. |
| Response: | ATSDR does not believe the public health assessment is irrelevant and
misleading. As required by the CERCLA, as amended by the Superfund
Amendments and Reauthorization Act (SARA), ATSDR must conduct a public
health assessment within one year of a site being proposed for listing on the
National Priorities List (NPL) (a.k.a., "Superfund"). In accordance with
ATSDR's procedures, an initial release public health assessment for the proposed
National Zinc Company site was completed one year after the proposed listing.
The initial release was reviewed by EPA and the State of Oklahoma.
ATSDR is not aware of any conflict between the public health assessment and the
Proposed Plan to clean-up the NZC site. The public health assessment concludes
and recommends that the site should be remediated. The Proposed Plan describes
remedial action alternatives considered for addressing the elevated metal
concentrations in the soil at the NZC site and identifies the remedial action
selected by the ODEQ. The public health assessment does not recommend how
and to what extent the site should be remediated. |
| Comment: | The document should be withdrawn or significantly revised. We strongly
recommend that the draft public health assessment either be withdrawn or be
revised to focus only on the evaluation of epidemiological data in response to
community health concerns. The document should simply refer the reader to the
EPA baseline risk assessment and the ODEQ Proposed Plan. |
| Response: | ATSDR has revised the NZC Public Health Assessment to include the
groundwater and ambient air monitoring data provided by two commentators.
These additional data did not change ATSDR's major conclusion that the NZC
site is a public health hazard.
As required by the CERCLA, as amended by the SARA, an ATSDR public health
assessment is required to evaluate the nature and extent of contamination,
pathways of human exposures, and the size and susceptibility of communities
within the likely pathways. In order to comply with this congressional mandate,
ATSDR must conduct its' own evaluation. ATSDR can not simply refer the
reader to other reports. This public health assessment was conducted in
accordance with the ATSDR Public Health Assessment Guidance Manual. |
| Comment: | The draft public health assessment should have been issued before the public
comment period for the RI/FS and certainly before issuance of the ODEQ's
Proposed Plan. |
| Response: | On May 15, 1994, ATSDR issued the initial release public health assessment for
the proposed NZC NPL site. In accordance with ATSDR procedures, the initial
release completed ATSDR's statutory requirements under CERCLA. Both EPA
and ODEQ were provided copies of the initial release prior to the release of the
EPA risk assessment or the ODEQ Proposed Plan.
ATSDR would have preferred to have issued the public comment release of this
public health assessment prior to the draft RI/FS. However, the accelerated
investigation and cleanup of this site, which ATSDR fully supports, resulted in
the public comment release being issued sightly after the draft RI/FS was
released. |
| Comment: | ATSDR should explain the inconsistencies and errors in the draft public health
assessment to the community. Specific examples were provided by the
commentator. |
| Response: | ATSDR will respond, below, to each of the specific comments. |
| Comment: | Page 1, last paragraph, 2nd bullet. Evaluation of groundwater as a threat to
human health should not be considered as a recommended action. |
| Response: | Based upon the data submitted by another commentator, ATSDR agrees that the
groundwater monitoring recommendation is not necessary. The public health
assessment has been revised accordingly. |
| Comment: | Page 4, 4th paragraph, last sentence. EPA removed soils from 25 (not 29) high
access areas and from 10 (not 11) residences. |
| Response: | The NZC Public Health Assessment has been revised accordingly. |
| Comment: | Page 5, 3rd paragraph, 2nd sentence. This sentence regarding finalization of NPL
listing is incorrect. |
| Response: | The sentence has been deleted from the public health assessment. |
| Comment: | Page 5, 5th paragraph, 3rd sentence. Final cleanup levels were not presented in
EPA's risk assessment but in the Proposed Plan by ODEQ based on information
presented in EPA's risk assessment and the RI report. |
| Response: | The public health assessment has been revised accordingly. |
| Comment: | Page 8, 3rd full paragraph, 1st sentence. ATSDR did not evaluate "... all
available environmental monitoring data (1971 to present)." That is the crux of
the problem. |
| Response: | ATSDR was not provided a copy of the RI/FS until September 14, 1994. The
public health assessment was issued on September 7, 1994. The relevant data in
the RI/FS has been added to the public health assessment. |
| Comment: | Page 17, 1st paragraph, 2 sentence. This sentence is incorrect and indicates
careless interpretation of data. Cadmium and lead could not have been
discharged from the smelter as indicated by the 1977 and 1992 ambient air data
because smelter discharges ceased after 1976. |
| Response: | As required by the Emergency Planning and Community Right-to-Known Act of
1986, the owners of the smelter reported to EPA that the Zinc Corporation of
America released to the air an average of 3,429 pounds of lead, 1,474 pounds of
cadmium, and 23,600 pounds of zinc each year for the years 1987 to 1991. This
information is presented and discussed in the public comment release public
health assessment. |
| Comment: | Page 18, last paragraph, 2nd sentence. This sentence is not correct. The RI data
indicated that garden soils had significant lower concentrations of arsenic,
cadmium, lead, and zinc than soils from the same yard. |
| Response: | This information will be incorporated into the public health assessment. This part
of the public health assessment discusses the potential exposure pathways.
Although this information indicates that the gardens sampled to date do not
appear to have significant metal concentrations, it does not preclude that gardens
in the past could have had significant metal concentrations which could have been
taken-up by plants. |
| Comment: | Page 19, 1st paragraph. Analysis of soil samples near the Caney River are not
particularly relevant to sediments in the Caney River downstream of Eliza Creek.
The facility ditch sediment sample referred to in the draft public health
assessment (Table 1) is not from "... local drainage ditches near the Caney River." |
| Response: | Nowhere in this paragraph does ATSDR refer to the sediment data contained in
Table 1. This paragraph discusses the sediment data taken in Eliza Creek and in
Caney River. Table 1 clearly states that the environmental data presented was
taken from locations at the Zinc Corporation of America.
This paragraph has been revised to clearly state how the agency came to its
conclusion. The data presented in the RI will also be included in this discussion. |
| Comment: | Page 22, Section 2. The possibility of health consequences. These evaluations
for cadmium and zinc are preliminary, screening level evaluations that are
superseded by the more exhaustive, site-specific analysis in the RI. |
| Response: | This part of the public health assessment was developed in accordance with the
ATSDR Public Health Assessment Guidance Manual. |
| Comment: | Page 23, 5th paragraph. Regarding the cancer risk associated with cadmium
inhalation, it is important to note that no single individual will be exposed to the
maximum observed cadmium concentration (0.61 µg/m3) for a lifetime. |
| Response: | This section of the public health assessment has been revised to clarify this issue. |
| Comment: | Page 23, 6th paragraph and page 24, 1st full paragraph. The inclusion of zinc as
a contaminant of concern is problematic. A flawed RfD for zinc was used and
applied to infants and children. ATSDR did not consider the antagonistic
interactions between cadmium and zinc. |
| Response: | ATSDR agrees that there is some uncertainty associated with the zinc RfD as it
applies to infants and children. In the toxicological section, ATSDR states that
there is some possibility of noncarcinogenic health effects for children exposed to
zinc in residential soil. However, ATSDR is uncertain that these health effects
would occur because of the different zinc metabolism between adults and children
(page 24 of the public comment release public health assessment).
ATSDR has added a new sub-section to the public health assessment which
discusses the interaction between cadmium, lead, and zinc. The information is
based upon the ATSDR Toxicological Profiles for cadmium, lead, and zinc. |
| Comment: | Page 28, 4th paragraph. The only recent body tissue data available are for lead,
consequently there is no evidence that site-related cadmium exposures are
occurring at the present time. Moreover, the results of a body tissue monitoring
study recently conducted by ATSDR in Palmerton, Pennsylvania suggests that
significant cadmium exposures are not currently occurring in Palmerton. Because
of the similar histories of the two sites and because the environmental cadmium
exposures would have been significantly less in Bartlesville, the results of the
ATSDR study in Palmerton strongly indicate that significant cadmium exposures
are not currently occurring in Bartlesville. |
| Response: | The public health assessment has been revised to clearly indicate that there is no
body tissue data for cadmium.
The ATSDR study in Palmerton found significantly higher urine cadmium level
in people from the target area than in the comparison area (ages 40 through 75).
ATSDR was not able to determine whether this difference was due to past or
current exposures. The results of the Palmerton study can not be directly related
to the situation in Bartlesville. The demographic make-up of Palmerton is
different than Bartlesville. In addition, Bartlesville has a different soil matrix
than Palmerton. |
| Comment: | Page 29, 5th paragraph. In explaining the wide range of increases in blood lead
levels associated with lead in soil, it is important to note that the smallest
increases in blood lead levels were observed in communities with mines or
inactive smelters. This observation has been explained by studies demonstrating
reduced absorption of lead from these soils. |
| Response: | This information has been added to the public health assessment. |
| Comment: | Page 33, Recommendation No 2 regarding determination of the total extent of
groundwater contamination. This recommendation is not relevant. |
| Response: | Based upon the data submitted by another commentator, ATSDR agrees that the
groundwater monitoring recommendation is not necessary. The public health
assessment has been revised accordingly. |
| Comment: | Page 33, Recommendation No. 3. Air emissions from the residual piles are being
controlled as indicated by the ongoing ambient air monitoring program under the
oversight of EPA Region VI. This recommendation is not relevant. |
| Response: | Based upon the data submitted by another commentator, ATSDR agrees. This recommendation has been revised to state that the control of air emissions from the residual piles should continue. |
FOOTNOTES
1. The National Toxicology Program in its Annual Report on Carcinogens classifies a chemical as a "known human carcinogen" based on sufficient human data. Its classification of a chemical as being "reasonably anticipated to be a carcinogen" is based on limited human or sufficient animal data.
2. IARC defines a class 1 carcinogen as a substance which studies in humans indicate a causal relationship between the agent and human cancer. Class 2 carcinogens are those reasonably anticipated to be carcinogens. For a 2A classification, there is limited evidence of carcinogenicity from human studies which indicate that a causal interpretation is credible, but not conclusive. A classification of 2B indicates that there is sufficient evidence of carcinogenicity from studies in experimental animals.
3. In EPA's classification scheme, a chemical is considered a class A or human carcinogen based on sufficient evidence from studies of humans. A substance is considered class B1 if there is limited evidence from human studies. B2 is used when evidence for carcinogenicity is inadequate or non-existent based on human studies, but sufficient based on animal studies.
4. Category I: The substance meets the definition of a
potential occupational carcinogen in (i) humans, or (ii) in a
single mammalian species.
Category II: The substance (i) meets the definition of a potential
occupational carcinogen but the evidence is suggestive.
5. The Maternal and Child Health Service, Oklahoma State Department of Health (OSDH), conducted the blood lead testing in collaboration with the OSDH environmental unit. The OSDH environmental unit became a part of the Oklahoma Department of Environmental Quality in 1993. The unit continues to oversee this work.
6. Personal communication with Monty Elder, Oklahoma Department of Environmental Quality.
