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PUBLIC HEALTH ASSESSMENT

PALMERTON ZINC PILE
PALMERTON, CARBON COUNTY, PENNSYLVANIA


APPENDIX A. FIGURES

Figure 1
Figure 1. Site Sketch


Figure 2. Contours of Zinc Concentrations in the Soil Around Palmerton, Pennsylvania


Figure 3. Contours of Lead Concentrations in the Soil Around Palmerton, Pennsylvania


Figure 4. Contours of Cadmium Concentrations in the Soil Around Palmerton, Pennsylvania



APPENDIX B. HEALTH CONSULTATION MEMORANDUM

April 12, 1993

Senior Toxicologist, TSS, ERCB, DHAC (E57)

Health Consultation: Palmerton Zinc Superfund Site (3026)
          Palmerton, Pennsylvania

Charles Walters
ATSDR Senior Regional Representative
EPA Region III
Through: Director, DHAC (E32)
          Chief, ERCB, DHAC (E57)
          Acting Chief, TSS, ERCB, DHAC (E57)


BACKGROUND AND STATEMENT OF ISSUES

The U.S. Environmental Protection Agency (EPA) has asked the Agency for Toxic Substances and Disease Registry (ATSDR) to evaluate public health threats posed by exposures to metals detected in areas surrounding the Palmerton Zinc Superfund Site (PZSS) in Palmerton, Pennsylvania and to comment on their proposed removal response action levels in residential surface soil and dust within homes where children 6 years old and younger and/or pregnant women reside. The proposed response will be taken at homes where contamination exceeds both 1,500 milligrams of lead per kilogram of soil (mg lead/kg soil) or dust and 100 mg cadmium/kg soil or dust [1]. Homes where only one of the metals is above the removal response action level will be evaluated on a case-by-case basis [1]. EPA has indicated that the proposed removal action is an interim measure and that future removal or remedial actions, targeted at lower lead and cadmium levels, may be necessary [20].

Palmerton is located in a rural area consisting of a series of deep, narrow valleys. This area has a population of approximately 13,000 persons with 5,500 residing in Palmerton itself. Approximately 850 persons live within 1 mile of the site (1980 census). The town lies in the Lehigh Valley along the Aquashicola Creek in Carbon County. Stony Ridge lies to the north of Palmerton; Aquashicola Creek, a trout-stocked stream, runs the length of the valley; and the Blue Mountain borders the valley on the south. The Appalachian Trail runs along the crest of Blue Mountain. The Lehigh Gap cuts through Blue Mountain south of Palmerton.

The PZSS consists of two separate zinc smelting plants, one east and one west of town. The site was placed on the National Priorities List (NPL) in 1982. The east plant is on the southern bank of the Aquashicola Creek, and the west plant is on the Lehigh River at its confluence with the Aquashicola Creek. The PZSS was used for primary zinc smelting from 1898 until 1980. In 1980, the east plant began a secondary metal refining and processing operation [2], and in 1987, the west plant closed [3]. Access to both the east and west facilities is restricted.

Environmental studies conducted in the Palmerton area have shown that metals such as lead and cadmium have been detected in various environmental media [2]. A 1987 Pennsylvania State University study investigating the uptake of cadmium by garden vegetables and the effect of cadmium and zinc on plants concluded that soils contaminated with high levels of zinc or cadmium will not support plant growth. The study also concluded that the dietary cadmium increase would be from 35 to 50 micrograms per day (µg/day) if a person grew all of his own vegetable intake [2]. Fish analyses were conducted by the U.S. Fish and Wildlife Service in 1985, and the data were analyzed by ATSDR in 1987 to determine if adverse health effects could occur if the fish were consumed. ATSDR concluded that fish from streams in the immediate area of Blue Mountain should not be consumed more than once per week [4].

In a study conducted by EPA in 1991, lead, cadmium, arsenic, and zinc were detected in area soils and in dusts in living spaces inside residences [5]. The data from the EPA study were analyzed by ATSDR's Division of Health Studies (DHS). Tables 1-4 provide a summary of the information derived from the DHS's analysis of the 1991 study. Previous studies are summarized in the draft of the Remedial Investigation and Risk Assessment, Volumes I through V, January 27, 1988 [2].

The DHS is conducting a human health study in the Palmerton area. Blood lead and urine cadmium levels are being investigated along with environmental levels of lead and cadmium. DHS used the environmental sampling data provided by EPA with the following changes: (1) environmental data from six homes were not included because the participants had lived in their homes less than 6 months or the home was located outside of the study boundary, the eligibility requirements for the study; (2) environmental sampling results measured at less than the detection limit were recorded as one-half the detection limit; (3) a few homes and facilities included in the EPA sampling were not part of the ATSDR study; and (4) all samples marked as either duplicates or not usable were deleted from the data set. Individuals participating in the study have been notified of their results. The results of this study will be available to the public early in 1993.

Contamination of the valley, Blue Mountain, and Stony Ridge with high concentrations of metals is believed to be due to smelter stack emissions and erosion of the massive tailings piles located at the east facility. Winds, which blow primarily from the northeast and southwest through the Lehigh Gap and continue northeasterly up the Aquashicola Creek valley [6] are a major factor in the distribution of the metals.

Many areas of Palmerton are devoid of vegetation, a factor which increases the likelihood of contaminant migration and uptake. The area surrounding the PZSS facilities has sparse vegetation. There is very little vegetation on contaminated areas of Blue Mountain, Stony Ridge, and the cinder bank located at the east plant. Residential yards in Palmerton have variable amounts of ground cover. Some of these yards are bare or have sparse vegetation, some have rock gardens, and some have had sod installed. Metals in surface water runoff from the denuded mountain and waste piles have been transported into area streams [4]. EPA is trying to minimize migration of contaminants from Blue Mountain by applying fly ash and waste water treatment sludge on its slopes to get vegetation to grow [7].

Because of the nature of the contamination, EPA has divided the site into four operable units. Operable Unit #1 is the defoliated north slope of Blue Mountain. Operable Unit #2 is the cinder bank at the east plant. Operable Unit #3 consists of off-site soils. Operable Unit #4 is focusing on surface water and groundwater [8]. Separate Remedial Investigations (Ris) are being conducted on the four operable units designated by EPA.

ATSDR's Division of Health Education (DHE) is providing health education in the Palmerton area. DHE has provided information and health education programs on lead and cadmium for physicians, nurses, and other health care providers. Staff from DHE have met with members of the Community Task Force and the Community Assistance Panel and has provided information about lead and cadmium toxicity for members of the community.

Table 1. Concentrations of lead detected in environmental media [5].

media
median
maximum
minimum
75%3
N4
bare soil1
474
5,050
3.1
782
82
garden soil1
248.5
932
38.1
309
40
perimeter soil1
579
10,600
26.4
1,020
161
sandbox &
play areas1
202
1,780
0.6
495
76
interior dust1
640.5
6,400
20
973
176
porch dust1
1,190
17,700
1.5
2,410
175
street dust1
935
14,300
49.4
1,470
173
30 min tap water2
1.5
43.3
0.3
2.1
176
overnight tap water2
1.6
31.4
1
2.6
166
1     mg lead/kg soil
2     microgram lead/liter water (ug lead/L water)
3     75 percentile
4     number of samples evaluated


Table 2. Concentrations of cadmium detected in environmental media [5].

media
median
maximum
minimum
75%3
N4
bare soil1
56.8
234
0.9
101
82
garden soil1
28.2
126
1.6
42
40
perimeter soil1
47
256
0.7
75
161
sandbox & play areas1
21.4
680
0.1
60
76
interior dust1
37.4
2,501
0.13
60
176
porch dust1
58
1,220
0.2
90
175
street dust1
62.4
664
8
91
173
30 min tap water2
2.5
11.7
0.5
2.5
176
overnight tap water2
2.5
10.6
0.5
2.5
166

1     mg cadmium/kg soil
2     ug cadmium/L water
3     75 percentile
4     number of samples evaluated


Table 3. Concentrations of zinc detected in environmental media [5].

media
median
maximum
minimum
75%3
N4
bare soil1
5,710
29,200
198
8,700
82
garden soil1
2,825
11,800
278
4,265
40
perimeter soil1
5,330
26,000
77.9
9,410
161
sandbox & play areas1
2,270
13,500
4
5,310
76
interior dust1
4,840
62,500
508
7,910
176
porch dust1
7,680
78,000
10
12,200
175
street dust1
11,300
94,200
284
17,500
173
30 min tap water2
558.5
1,250
11.8
620
176
overnight tap water2
716.5
1,840
8.5
881
166
1     mg zinc/kg soil
2     ug zinc/L water
3     75 percentile
4     number of samples evaluated


Table 4. Concentrations of arsenic detected in environmental media [5].

media
median
maximum
minimum
75%3
N4
bare soil1
22.2
138
5.2
34
82
garden soil1
14.9
45
5.3
18.9
40
perimeter soil1
19.l3
138
0.76
31.9
161
sandbox & play areas1
13.3
140
0.4
24.7
76
interior dust1
12.2
503
0.1
19.7
176
porch dust1
11.1
213
0
22.7
175
street dust1
94.3
492
3.5
137
173
30 min tap water2
5
10
1
5
176
overnight tap water2
5
5
1
5
166
1     mg arsenic/kg soil
2     ug arsenic/L water
3     75 percentile
4     number of samples evaluated


DISCUSSION

The primary routes of human exposure to the contaminants detected in off-site areas are ingestion and inhalation. Ingestion of contaminated soil via hand-to-mouth activities may be an important route of exposure, particularly among children. Consumption of contaminated water or food can also result in exposure. Inhalation of airborne particulates can be another important route of exposure.

The levels of the metals detected in environmental media are only one factor that needs to be considered when evaluating potential exposures and health threats. For this consultation, other site-specific factors such as extent of vegetation, frequency and duration of exposure, and sensitive populations were also evaluated.

Opportunities for exposure are greater when there are no protective barriers (e.g., vegetation, pavement, or concrete cover) between people and sources of contamination such as soil. Large areas of Blue Mountain, Stony Ridge, and the cinder bank do not have protective barriers. Many of the yards in residential areas do not have barriers between people and contaminated soil. Although the public does not have access to the cinder bank on-site at the PZSS facility, wind and precipitation may transport materials in the cinder bank off-site. Access is not restricted to contaminated off-site areas such as the mountains surrounding the PZSS facilities. Again, wind and precipitation can result in relocation of contaminants from these areas. EPA's attempts to vegetate Blue Mountain will help prevent migration of these contaminants.

The frequency and duration of human exposure to lead, cadmium, zinc, and/or arsenic are difficult to determine. Elevated levels of these metals were not detected at all sampling locations nor were they universally elevated in areas where sensitive populations such as small children are frequently found. Sand box/play areas, bare and garden soil, and interior and porch dusts are areas where direct contact with the contaminated medium can occur; consequently, the frequency and duration of exposures are likely to be greater in these areas than in areas such as soil in residential yards that are vegetated or have some type of barrier between people and the contaminated medium. Due to infrequent contact, metals in street dusts, or on the cinder bank or mountains represent the least threat to human health as long as the contaminants remain where they are. Street dusts, material from the cinder bank, or soil from the surrounding mountains that are transported into high human contact areas become greater health threats since both increased frequency and increased duration of contact with contaminants are likely to occur.

Education can be effectively used to minimize exposure to hazardous substances. Information and training has been provided to health care providers in Palmerton concerning biological monitoring and potential adverse health effects that may occur in people that are exposed to lead and cadmium. The general public has also been advised about potential adverse health effects associated with exposure to lead and cadmium.

Certain subgroups of the population may be more susceptible to the toxic effects of lead exposure. These include preschool age children (less than 6 years old), pregnant women, fetuses, elderly, smokers, alcoholics, and people with genetic diseases affecting heme synthesis, nutritional deficiencies, and neurological or kidney dysfunction [9].

Specific subgroups that are susceptible to the effects of cadmium, arsenic, and zinc have not been unequivocally identified; however, susceptible populations may exhibit a different or enhanced response to these metals than will most persons exposed to the same level of these contaminants in the environment. Reasons include genetic makeup, developmental stage, health and nutritional status, and chemical exposure history. These parameters result in decreased function of the detoxification and excretory processes (mainly hepatic and renal) or the pre-existing compromised function of target organs. For these reasons, ATSDR expects that the elderly with declining organ function and the youngest in the population with immature and developing organs will generally be more vulnerable to these substances than healthy adults [10, 11, 12].

Lead in the environment may cause serious adverse health effects, particularly in young children. Young children and fetuses are especially sensitive to the toxic properties of lead. Factors accounting for this susceptibility include (1) the immaturity of the blood brain barrier which allows entry of lead into the immature nervous system; (2) hand-to-mouth behavior and pica behavior which leads to consumption of lead contaminated media; (3) enhanced gastrointestinal absorption of lead (affected by the nutritional status of the child); (4) low body weight; and (5) the ready transfer of lead across the placenta to the developing fetus [9]. These factors put children exposed to lead at a much higher risk of developing adverse health effects than adolescents and adults.

Studies indicate that ingestion and inhalation of lead contaminated soil can lead to elevated blood lead levels and adverse health effects. Blood lead levels of 10 micrograms per deciliter (ug/dL) and above have been associated with adverse developmental effects in fetuses and hearing impairment, growth impairment, and reductions in intelligence quotient (IQ) in children [9, 14]. Lead has long been known to have effects on heme biosynthesis. Lead inhibits the activity of certain enzymes involved in heme biosynthesis such as -aminolevulinic acid dehydratase (ALAD). Reductions in ALAD production in adults have been demonstrated at an oral dose of 0.02 mg/kg/day for 3 days and at air concentrations of as little as 3.2 micrograms of lead per cubic meter of air (ug/m3) for 3 to 4 months [9].

Since lead readily crosses the placental barrier, exposure of women to lead during pregnancy results in uptake by the fetus. Prenatal exposure to lead (8-14 ug/dL fetal cord blood lead level) is associated with premature delivery, decreased birth weight, impaired postnatal neuro-behavioral development, and decreased postnatal growth rate [9].

Blood levels in young children are raised, on average, about 5 ug/dL for every 1,000 mg/kg of lead in soil or dust, and may increase 3 to 5 times higher than the mean response depending on play habits and mouthing behavior. Even lower soil levels of lead (150 to 250 mg/kg) have been suggested as contributing to excessive blood lead levels in some children [15, 16]. Ingestion of 200 mg of soil per day (mg soil/day) containing 1,780 mg lead/kg soil (the maximum amount of lead found in a sandbox/play area) by a 10 kg child would result in a dose of 0.04 mg/kg/day. A dose of 0.05 mg/kg/day for 5 days per week for 200 days has been shown to cause adverse neurological effects in monkeys [9]. Ingestion of the maximum level of lead detected at an accessible off-site area (see Table 1) by a 10 kg child would result in a dose of 0.5 mg/kg/day. Ingestion of contaminated food could appreciably increase the dose of lead.

Mouthing activities by infants and pica behavior by young children could result in a several fold increase in the dose of lead [16]. Infants and young children have a normal propensity for ingestion of non-food items. Pica behavior is a compulsive ingestion of non-food items and has a typical onset in the second year of life [17]. Soil and dust ingestion rates are highly variable and are affected by several factors including seasonal changes, socioeconomic and cultural factors, degree of exposed versus covered soils and dusts, and variations in nutritional status of the people being evaluated [16]. Soil ingestion rates for children have been reported to range from 16 to 191 mg/day [13]. Five thousand milligrams soil per day is considered to be an appropriate ingestion level for children with pica behavior [16].

Inorganic arsenic is a human carcinogen via the inhalation pathway. Epidemiological studies of workers demonstrated that the risks of respiratory cancer increased as the concentration of arsenic in the air increased. Airborne concentrations that resulted in an increased incidence of cancer in those studies ranged from 10 to 300 micrograms of arsenic per cubic meter of air (ug/m3) [11].

There is convincing evidence from a large number of epidemiological studies and case reports that ingestion of inorganic arsenic increases the risk of developing skin cancer. There is also evidence that ingestion of arsenic increases the risk of cancer in other tissues and organs. These studies indicate that exposure to levels ranging from 0.009 to 0.04 mg/kg/day for several years have been associated with an increased incidence of cancer [11].

Chronic exposure to arsenic can result in a variety of noncarcinogenic adverse health effects. Ingestion of low levels of arsenic has been shown to cause adverse health effects such as gastrointestinal disturbances (0.05 mg arsenic/kg/day for 2-3 weeks), pigmentation of the skin (0.05 mg arsenic/mg/day for 0.5-15 years), peripheral neuropathy (0.05 mg arsenic/kg/day for 0.5-15 years), and adverse cardiovascular effects (0.05 mg arsenic/kg/day for 2-3 weeks) [11]. Inhalation of arsenic has been shown to cause adverse immunological effects in laboratory animals. Alveolar macrophage injury was observed when mice were exposed to levels as low as 0.94 mg arsenic/m3 for less than 1 week and 0.5 mg arsenic/m3 for 4 weeks [11].

EPA's oral Reference Dose (RfD) for arsenic is 0.0003 mg/kg/day [18]. An RFD is an estimate (with uncertainty spanning perhaps an order of magnitude) of the daily exposure of the human population to a chemical that is likely to be without risk of deleterious, noncancerous effects during a lifetime. If a 10 kg child were to ingest 200 mg soil/day containing 15 mg arsenic/kg soil, the amount of arsenic ingested would be 0.0003 mg/kg/day, a dose equal to the RfD. Ingestion of 200 mg soil/day containing 140 mg arsenic/kg soil (the maximum amount of arsenic found in a sandbox/play area) by a 10 kg child would result in a dose of 0.003 mg arsenic/kg/day. Ingestion of the maximum level of arsenic detected at an accessible off-site area would result in a dose of 0.01 mg/kg/day. Mouthing activities by infants and pica behavior by young children could result in a several fold increase in the dose of arsenic [16].

The kidney is the most sensitive target organ for chronic oral exposure to cadmium [10]. Following absorption from the gastrointestinal tract, cadmium is distributed throughout the body and preferentially accumulates in the kidney and liver [10]. Cadmium is excreted very slowly from the body, and its half-life in humans has been estimated to be 10-38 years [19].

Cadmium concentrations in the kidney are near zero at birth, but increase roughly linearly with age and peak between ages 50 and 60. After the age of 60, kidney concentrations begin to decline slowly [19]. Human studies have indicated that adverse renal effects may occur when the concentration of cadmium in the renal cortex exceeds 200 micrograms/gram (ug/g) wet weight [10]. When this critical concentration is exceeded, proteinuria, as manifested by increased urinary excretion of low molecular weight proteins such as beta 2-microglobulin, can occur.

EPA derived an oral RfD for cadmium in food of 0.001 mg/kg/day [18]. If a 10 kg child were to ingest 200 mg soil/day containing 50 mg cadmium/kg soil, the amount of cadmium ingested would be 0.001 mg/kg/day, a dose equal to the RfD for food. If the same child ingested soil from a sandbox/play area containing 680 mg cadmium/kg soil (see Table 2), the dose would be 0.01 mg/kg/day. Ingestion of the maximum level of cadmium detected at an accessible off-site area would result in a dose of 0.05 mg/kg/day. Ingestion of contaminated food could appreciably increase the dose of cadmium. Mouthing activities by infants and pica behavior by young children could result in a several fold increase in the dose of cadmium [16].

Zinc is an essential element required for normal growth, bone formation, brain development, behavior, reproduction, fetal development, sensory function (taste and smell), immune function, membrane development, and wound healing. The recommended dietary allowance for zinc is 5 mg/day for infants (0-1 year), 10 mg/day for children (1-10 years), 15 mg/day for males (11-51 years), 12 mg/day for females (11-51 years), 15 mg/day for pregnant women, 19 mg/day for women during the first 6 months of lactation, and 16 mg/day during the next 6 months of lactation [12]. Excessive zinc intake, however, can cause adverse health effects. Ingestion of 2 to 4 mg zinc/kg/day (140 to 280 mg/day for a 70 kg person) for several weeks has been shown to cause a reduction in high density lipoproteins, an increase in low density lipoproteins, and produced adverse gastrointestinal effects. Chronic ingestion of similar levels of zinc has resulted in decreased hematocrit [12].

The RfD for zinc is 0.3 mg/kg/day [18]. If a 10 kg child were to ingest 200 mg soil per day containing 15,000 mg zinc/kg soil, the amount of zinc ingested would be 0.3 mg/kg/day, a dose equal to the RfD. If the same child ingested soil from a sandbox/play area containing 13,500 mg zinc/kg soil (see Table 3), the dose would be 0.27 mg/kg/day. Ingestion of the maximum level of zinc detected at an accessible off-site area would result in a dose of 1.6 mg/kg/day. Mouthing activities by infants and pica behavior by young children could result in a several fold increase in the dose of zinc [16].


CONCLUSIONS

Based on the information reviewed, ATSDR concludes the following:

  • The levels of lead, cadmium, zinc, and arsenic detected in the Palmerton areas sampled may pose a health threat, particularly to young children;

  • EPA's removal action levels of both 1,500 mg lead/kg and 100 mg cadmium/kg residential soil or interior dust may not be protective of the health of children and pregnant women;

  • EPA has not developed removal action levels for arsenic and zinc;

  • Migration of contaminants has occurred in the past and may currently be occurring;

  • EPA is attempting to control erosion of the bare, contaminated surfaces of Blue Mountain; and

  • ATSDR has provided educational materials to health care providers and the public.


RECOMMENDATIONS

  • Consider lowering the removal action levels for lead and cadmium in areas such as sandboxes, day care centers, interior dusts, and park areas where there are no protective barriers between the contamination medium and people, and where frequency and duration of exposure are likely to be high for sensitive populations;

  • Consider having independent removal action levels for lead and cadmium rather than requiring both to be elevated before removal action will be taken;

  • Develop removal action levels for arsenic and zinc;

  • Continue to implement measures to prevent migration of contaminants; and

  • Continue to provide educational materials to the public and health care providers as appropriate.

If additional information becomes available or if further clarification is required, please contact this office at (404) 639-6360.

                                                                            Raymond E. Grissom, Ph.D.

            Concurrence: Steven Haness, Ph.D.

cc:
Sara Sarasua

ATSDR:DHAC:ERCB:TSS:Rgrissom:jaf:4/12/93:6360
Doc: PAL.11


REFERENCES

  1. U.S. Environmental Protection Agency. Request for Funds for a Removal Action, Palmerton Zinc NPL Site, Palmerton, PA. March 3, 1993. From: A.F. Koller, EPA III Remedial Project Manager, To: S.L. Laskowski, EPA Acting Regional Administrator.

  2. Remedial Investigation Contractor (REWAI). Palmerton Zinc Off-Site Study Area Draft of Remedial Investigation and Risk Assessment, Volumes I through V, January 27, 1988.

  3. U.S. Environmental Protection Agency. Declaration for the Record of Decision, Operable Unit #2, June 1988, U.S. Environmental Protection Agency, Region IV, Philadelphia, Pennsylvania.

  4. Agency for Toxic Substances and Disease Registry. Preliminary Health Assessment Palmerton Zinc Site, February 4, 1987, U.S. Department of Health and Human Services, Agency for Toxic Substances and Disease Registry, Atlanta, Georgia.

  5. U.S. Environmental Protection Agency. Palmerton zinc pile superfund site amended quality assurance project plan. October 8, 1991.

  6. U.S. Environmental Protection Agency. ERC Report on Palmerton, January 1989, U.S. Environmental Protection Agency, Environmental Research Center, Las Vegas, Nevada.

  7. U.S. Environmental Protection Agency. Declaration for the Record of Decision, Operable Unit #1, September 1987, U.S. Environmental Protection Agency, Region III, Philadelphia, Pennsylvania.

  8. U.S. Environmental Protection Agency. Superfund Program Fact Sheet, Palmerton Zinc Site, May 1988, U.S. Environmental Protection Agency, Region III, Philadelphia, Pennsylvania.

  9. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Lead, U.S. Public Health Service, Agency for Toxic Substances and Disease Registry, Atlanta, Georgia, October 1991.

  10. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Cadmium, U.S. Public Health Service, Agency for Toxic Substances and Disease Registry, Atlanta, Georgia, October 1991.

  11. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Arsenic, U.S. Public Health Service, Agency for Toxic Substances and Disease Registry, Atlanta, Georgia, October 1991.

  12. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Zinc, U.S. Public Health Service, Agency for Toxic Substances and Disease Registry, Atlanta, Georgia, October 1992.

  13. Stanek E , E Calabrese, and L Zheng, 1990. Soil ingestion estimates in children: influence of age and sex. Trace Substances in Environmental Health 24:33-43.

  14. Centers for Disease Control. Preventing Lead Poisoning in Young Children. October 1991.

  15. Chaney RL and HW Mielke, 1986. Standards for soil lead limitations in the United States. Trace Substances in Environmental Health 20:355-377.

  16. Reagan PL and EK Silbergeld, 1990. Establishing a health based standard for lead in residential soils. Trace Substances in Environmental Health 23:199-238.

  17. Dorland's Illustrated medical Dictionary, 1988.

  18. IRIS, 1993. Integrated Risk Information System. U.S. Environmental Protection Agency, Washington D.C.

  19. U.S. Environmental Protection Agency, Final Draft for the Drinking Water Criteria Document on Cadmium, April, 1985.

  20. U.S. Environmental Protection Agency. Palmerton Zinc Draft Consultation. March 23, 1993. Personal Communication: From: A.F. Koller, EPA III Remedial Project Manager, To: Jack Kelly, ATSDR Region III representative.


ATTACHMENT

PUBLIC COMMENTS AND RESPONSE

Comments received in a March 8, 1993, letter are presented here. The person commenting had concerns about the case-control study by the National Cancer Institute (NCI) that was briefly referred to in the Health Outcome Data Evaluation section of the public health assessment.

Comment: The NCI Study indicated "a two fold risk for lung cancer was associated with residences near the smelter" and the reviewer states this is inaccurate and not statistically significant.

Response: The NCI Study, based on their method of analysis, did show this statistic; however, as pointed out by the reviewer, this difference was only apparent for a select four year period and only when comparing the data to the specified control area. When compared to the State mortalities or to other time periods this was not true. (See Health Department Data Outcome). It also is true that the number of individuals involved were few and that it was not statistically significant. This report was referenced in the public health assessment because all available health outcome data for the area are evaluated. Inclusion of the study in that section of the document does not substantiate the study's accuracy or completeness.


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