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HEALTH CONSULTATION

JACOBS SMELTER SITE
STOCKTON, TOOELE COUNTY, UTAH


BACKGROUND AND STATEMENT OF ISSUES

Mr. Jeff Coombs, Director of Environmental Health, Tooele County Health Department (TCHD)requested that the Environmental Epidemiology Program (EEP) review the potential for adversehealth effects resulting from exposure to lead and arsenic in the soils at Stockton, Utah. The U.S.Environmental Protection Agency (USEPA) has conducted a survey of soil lead and arseniclevels. The TCHD, with assistance from USEPA, conducted a survey of blood lead levels andurine arsenic levels.

The Jacob's Smelter site is located in the town of Stockton, Tooele County, Utah. Stockton is acommunity with 437 residents located on State Route 36, approximately 5 miles south of TooeleCity, Utah. The town is approximately 45 miles southwest of Salt Lake City, Utah. Development of the mining industries in Stockton started following the discovery of silver andlead in the foothills east of the town. Numerous smelters were built around Stockton to supportmore than 100 operating mines and leases. Mining activities were at their height during the1870s (1, 2).

In 1997, the Utah Department of Environmental Quality (UDEQ) collected 29 soil samples fromStockton and the surrounding area. Analysis of the samples revealed the presence of elevatedlevels of lead (maximum = 68,400 mg/kg of soil) and arsenic (maximum = 30,400 mg/kg of soil)in the soil. The concentrations of those metals are much higher than are usually encountered inresidential areas and could be a potential health concern to area residents (2).

Following the discovery of high levels of lead and arsenic in residential area soils, USEPA andthe Bureau of Reclamation (BOR) conducted a much more extensive soil sampling study of thearea to identify residences where the lead levels were above 3,000 mg/kg of soil. The results ofthat investigation were presented to the community on January 21, 1999, (3) and emergencyremedial action was begun March 1, 1999, to remove those soils.


DISCUSSION

Environmental Data

Soil Lead Concentrations: Four hundred eighty seven surface soil samples (0-2 inches) werecollected from 248 properties within the residential area during the summer months of 1998. Those samples were evaluated for lead and arsenic using X-ray fluorescence (XRF) technology. The soil concentrations of lead ranged from 13 mg/kg to 41,537 mg/kg, with an averageconcentration of 1,474 mg/kg (2). Figure 1 presents a map of Stockton showing the leadconcentrations (4). Ten percent of the samples were also analyzed by Inductive Coupled PlasmaMass Spectrometry (ICP-MS). Subsurface samples were taken from 242 of the original samplingsites for samples 2-6, 6-12, and 12-16 inches below the surface. The soil lead levels wereconsistent through the different depths, indicating that no gradient of concentration of lead is inthe soil as a function of depth. The primary phase of lead in the soil is cerussite (PbCO3), whichaccounts for approximately 73% of the soil lead mass. The lead bearing soil particles tended tobe small (< 100 µm in diameter) and are not tightly bound or integrated with the surrounding matrix, increasing the bio-availability (2).

Soil Arsenic Concentrations: Difficulties were encountered in detecting arsenic by the XRF method because of strong masking by the presence of high levels of lead in the sample. However, laboratory analysis via ICP demonstrated a strong correlation between lead and arsenic, making it possible to estimate the concentrations of arsenic in the soil. The estimated soil concentrations of arsenic ranged from 12 mg/kg to 2,728 mg/kg with an average concentration of 108 mg/kg. The primary phases of arsenic are lead arsenic oxide (PbAsO, 52% of the soil arsenic), arsenic iron oxide (AsFeO, 34%), and arsenic iron sulfide (AsFeSO4, 12%). Most of the particles are small (<100 µm in diameter) and are almost completely (87-100%) liberated from the surrounding soil matrix (2).

House Dust Lead and Arsenic Concentrations: Indoor house dust samples were obtained from atotal of 23 residences in Stockton. Samples were collected from three locations (each 0.33 m2)within each residence. Samples were analyzed for lead and arsenic. Indoor dust lead levelsranged from 103 mg/kg to 1,370 mg/kg with a mean lead concentration of 455 mg/kg. Indoordust arsenic levels ranged from 8 mg/kg to 153 mg/kg with a mean lead concentration of 40mg/kg (2).

Potential for Lead Contamination in the Drinking Water: All residences in Stockton are on a community water source. Water is obtained from Soldier Canyon and is processed by a slow sand filter treatment plant (6). First flush water samples were taken from 23 homes. The measured concentration of lead in the tap water ranged from <2 to 5 µg/L with an average lead concentration of 1.2 µg/L (2).

Biomonitoring Data

During September of 1998, Tooele County Health Department (TCHD) and USEPA conducted abiomonitoring study among residents of Stockton to investigate exposure to lead and arsenic. Participants were identified by conducting a door-to-door survey and selected from residentsliving within areas where the soil lead level was above 500 ppm (500 mg / kg of soil). Fourteenhomes with children less than seven years of age were identified in the study area. A total of 26children is living in the study area. Residents from eight of the 14 homes with children andresidents from six additional homes participated in the study. Blood lead levels were measuredfor 16 of the 26 children that were less than seven years old and 10 older persons (7 to 21 yearsof age) from those homes (1). Urine arsenic levels were measured for 10 children that were less than seven years old and 22 older persons (7 to 63 years of age) from those homes (1, 2).

All blood lead tests were below 10 µg/dL. All urine arsenic tests, except one, were below the detection limit (<15 µg/L). The one elevated arsenic level was found to be organic arsenic and was attributed to diet and not to environmental exposure to the arsenic in the soil in Stockton (1).

Public Health Concerns and Demographics

Chemicals of Concern: Lead and arsenic are present in the soil at concentrations that pose potential adverse health effects to exposed persons. House dust samples collected indicate that excessive indoor lead and arsenic contamination from the soil is not occurring (2). However, the baseline risk assessment discussed the relative liberation and bio-availability of the metal-containing particles. This suggests that while a completed pathway may not be shown for inside homes, there is a high potential for adults and children working and playing in their yards and surrounding contaminated areas to be exposed. Since all residences are connected to a community public water supply which is offsite, water is not a source of exposure.

Possibly Exposed Population: The population of Stockton is a predominately white communityof approximately 437 residents. Approximately 6% of the population is Hispanic (5).Approximately 80 children, ages 0-6 years old, live in Stockton, with 26 children living in areasin which the soil lead concentration was detected above 500 ppm. The majority of the residentslive on the east side of Highway 36 (Conner Avenue) and in the northern half of the community. School children are bussed into Tooele (approximately 5 miles to the north). Blood lead levelsand urine arsenic measurements in study participants indicate that children and adults were notexposed to excessive levels of either lead or arsenic from the contaminated soil.

Adverse Health Effects of Lead Exposure: Lead poisoning is the most significant and prevalent disease of environmental origin in the United States, particularly among children. Lead exposure in children is a particular hazard because children absorb lead more readily than do adults. Environmental lead is a toxic substance that is affecting the growth and development of up to one million U.S. preschool children today, with effects that include learning disabilities and possibly more serious effects, depending upon blood lead levels (6). High levels of lead can adversely affect many systems in the body, including the neurological, reproductive, gastrointestinal, hematopoietic, and renal systems (7). The effect of lead that is usually considered to be of the greatest concern in children is the impairment on the neurological system and the resulting developmental and behavioral problems (2, 6). Blood lead levels as low as 10 µg/dL can adversely affect the behavior and development of children (8). Figure 2 provides shows blood lead levels at which the lowest observed health are seen (12).

During September of 1998, TCHD and EPA tested the blood lead levels of a small group of residents of Stockton living within areas where the soil lead level was above 500 ppm. All blood lead test results were below 10 µg/dL, within the normal range. Based on the limited data obtained by TCHD and EPA, the residents of Stockton did not have significant lead exposure from the contaminated soil or from other sources prior to September 1998. Blood lead tests can only detect recent lead exposure and cannot provide accurate information on exposure that occurred earlier than two to three weeks prior to testing (8).

Studies have found that on a volume basis, up to 16% of house dust was lead dust derived from apaint source and up to 26% of house dust was lead dust derived from mining wastes. Thosestudies suggest that the contribution of lead from mining and smelting wastes were at least asimportant a source as lead-based paint for exposure of children to lead (10, 11).

Adverse Health Effects of Arsenic Exposure: Organic arsenic is relatively non-toxic. However,ingestion of as little as 20 mg of inorganic arsenic may produce life-threatening toxicity. Themost sensitive body sites to arsenic include the respiratory system, the liver, the heart, thehematopoietic system, the kidneys, and central nervous system (9).

Arsenic can enter the body by ingestion and inhalation. Absorption by ingestion is generallyrapid and complete. Absorption by inhalation with the exception of certain salts of arsenite andarsenate are also rapid and nearly complete. Dermal contact may result in some localizedtoxicity; however, there is no evidence of direct dermal absorption of arsenic. The half-life ofwhole body arsenic is approximately five days (9).

The TCHD and EPA investigation conducted in September 1998 included arsenic exposuretesting. No one tested was found to have elevated levels of arsenic in their urine that could be attributed to arsenic from the site. The one elevated arsenic level was attributed to diet.


CHILD HEALTH INITIATIVE

Approximately 80 children under the age of seven years old live in Stockton, and 26 children livein areas with soil lead levels above 500 ppm. Young children are at particular risk fromenvironmental exposure to lead and arsenic because they are more sensitive to the toxic effects ofthose metals. Children are less developed and may have developmental harm from exposure thatwould not be experienced by a completely developed adult. Neurological development is ofparticular concern for children because lead and arsenic exposure can cause learning andbehavioral disabilities. In addition, children are more likely to have behaviors that will increase soil exposure.


CONCLUSIONS

The Jacob's Smelter Site is considered a public health hazard (ATSDR health hazard category B)because of the high levels of lead and arsenic in the soil in residential areas. However, biologicaltesting for blood lead and urine arsenic did not indicate that the residents were exposed toexcessive levels of lead or arsenic.

Emergency cleanup efforts have begun to remove the most accessible layer of dirt (the topeighteen inches) with plans to evaluate the site for further remediation. The cleanup activitieswill remove the health hazard associated with the contaminated soil. However, during thecleanup process, the community may be exposed to high levels of lead or arsenic from thecontaminated dust generated during the soil removal activities.


RECOMMENDATIONS

  1. Appropriate remedial actions should be taken to prevent exposure during clean-upactions.

  2. Community education on the adverse health effects of lead and arsenic should beprovided to Stockton residents. This information should include methods of controllingand reducing exposure to contaminated dust generated during the cleanup process.

  3. Blood lead testing of children ages 0-5 years of age that have not previously been tested and follow-up blood lead screening every 6 months during the cleanup is encouraged.

PUBLIC HEALTH ACTION PLAN

EEP will work with the TCHD to provide effective community education about the risks of lead and arsenic exposure to the community during the cleanup process and about methods to reduce exposures to lead and arsenic.

EEP will assist TCHD in monitoring the efficacy of EPA's emergency response clean-upactivities to minimize exposure of the residents of Stockton to lead-contaminated soils. EEP will review data reported to the Utah Blood Lead Registry for trends in blood lead levels among Stockton residents and will provide summary reports of those trends to UDEQ and to TCHD.

EEP will work with TCHD to encourage continued screening of children in Stockton for blood lead levels and will monitor the results of that screening in order to identify any increases in blood lead levels that may indicate increased exposure.


REFERENCES

  1. ISSI Consulting Group, Inc. (1999). Data Report: Bio-monitoring Investigation, Jacob'sSmelter - Stockton, Utah, February 1999. Prepared for US EPA Region 8 by ISSIConsulting Group, Inc., 999 18th Street, Suite 1450. Denver, Colorado 80202.

  2. ISSI Consulting Group, Inc. (1999). Baseline Human Health Risk Assessment, JacobsSmelter Site, Stockton, Utah, Risks to Residents From Arsenic and Lead in Soil. February 26, 1999. Prepared for US EPA Region 8 by ISSI Consulting Group, Inc., 99918th Street, Suite 1450. Denver, Colorado 80202.

  3. Environmental Epidemiology Program. (1999). Memorandum for the Record: EPACommunity Meeting, Stockton, Utah, January 22, 1999. Bureau of Epidemiology, UtahDepartment of Health, Salt Lake City, Utah.

  4. Environmental Epidemiology Program. (1999). Memorandum for the Record:Development of ArcView Map of Stockton Soil Lead Levels. Bureau of Epidemiology,Utah Department of Health, Salt Lake City, Utah.

  5. Environmental Epidemiology Program. (1999). Memorandum for the Record:Conversation with Stockton City Office. Bureau of Epidemiology, Utah Department ofHealth, Salt Lake City, Utah.

  6. Holtz, M., Kniepmann, K., and Kohn, L. (1998), Occupational Therapy in Pediatric LeadExposure Prevention. American Journal of Occupational Therapy, 52(1):53-59.

  7. Agency for Toxic Substances and Disease Registry. (1993). Toxicological Profile forLead. USDHHS (PHS), Atlanta Georgia (publication number PB93-182475).

  8. Centers for Disease Control and Prevention. (1991). Preventing Lead Poisoning inYoung Children. U.S. Department of Health and Human Services. Atlanta, Georgia.

  9. Ryan, R. P., and Terry, C. E. (1997). Toxicology Desk Reference. The Toxic Exposureand Medical Monitoring Index, 4th Ed. (1997-1998). Taylor & Francis, Publishers, Bristol, Pennsylvania.

  10. Sterling, D. A., Johnson, D. L., Murgueytio, A. M., and Evans R. G. (1998), SourceContributions of Lead in House Dust from a Lead Mining Waste Superfund Site. Journalof Exposure Analysis and Environmental Epidemiology, 8(3):359-373.

  11. Murgueytio, A. M., Evans, R. G., Sterling, D. A., Clardy, S. A., Shadel, B. N., and Clements, B.W. (1998), Relationship Between Lead Mining and Blood Lead Levels inChildren. Archives of Environmental Health, 53(6):414-423.

  12. Agency for Toxic Substances and Disease Registry. (1992). Case Studies inEnvironmental Medicine: Lead Toxicity. USDHHS (PHS), Atlanta, Georgia.

REPORT PREPARED BY

Samuel D. LeFevre, M.S., Epidemiologist
Environmental Epidemiology Program
Bureau of Epidemiology
Utah Department of Health

R. Wayne Ball, Ph.D., DABT
Toxicologist
Environmental Epidemiology Program
Bureau of Epidemiology
Utah Department of Health


CERTIFICATION

This Jacob's Smelter Site Health Consultation was prepared by the Utah Department of Health,Environmental Epidemiology Program under a cooperative agreement with the Agency for ToxicSubstances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the public health consultation was begun.

Gail D. Godfrey
Technical Project Officer, SPS, SSAB, DHAC


The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health consultation and concurs with the findings.

Sven Rodenbeck
Chief, SPS, SSAB, DHAC, ATSDR


APPENDIX

Table 1.

Summary of Environmental Data for Stockton, Tooele County, Utah, Collected by the U.S. Department of Environmental Quality During the Summer of 1998.
    LEAD ARSENIC

Soil Concentrations Average
Range
1,474 mg/kg
13 - 41,537 mg/kg
108 mg/kg est.
12 - 2,728 mg/kg est.
EPA Bare Residential
Soil Action Level
Interim
Abatement
400 mg/kg†
5,000 mg/kg†
 
House Dust Average
Range
455 mg/kg
103 - 1,370 mg/kg
40 mg/kg
8 - 153 mg/kg
Drinking Water Concentrations Average
Range
1.2 µg/L (ppb)
<2 - 5 µg/L (ppb)
 
EPA Drinking Water Action Level   15 µg/L (ppb)‡ 50 µg/L (ppb)‡

† Federal Registry, Vol 60 No 175 (September 11, 1995), page 47253.
‡40 CFR 141.80 Lead and Copper Rule

Map of Stockton, Tooele County, Utah Showing Soil Lead Levels
Figure 1. Map of Stockton, Tooele County, Utah Showing Soil Lead Levels.

Lowest Observable Adverse Effects Levels of Inorganic Lead on Children and Adults
Figure 2. Lowest Observable Adverse Effects Levels of Inorganic Lead on Children and Adults (12)


Table 2.

Completed Environmental Exposure Pathways
Pathway Name: Source Medium Exposure Point Exposure Route Receptor Population Time of Exposure Exposure Activity Estimated Number Exposed Chemicals (identify by name or reference to tables in document)
Residential Soil Smelter Tailings Soil Residential Property Ingestion of Soil Stockton Residents Past,
Present,
Future
Activities in yard.
Gardening.
437 total
26 children
Lead
Arsenic
Ingestion of Produce Eating produce from home garden.
Inhalation of Contaminated Dust Wind blown dust.


Table 3.

Potential Environmental Exposure Pathways
Pathway Name: Source Medium Exposure Point Exposure Route Receptor Population Time of Exposure Exposure Activity Estimated Number Exposed Chemicals (identify by name or reference to tables in document)
Residential Soil Smelter Tailings Soil Residential Property Ingestion of Soil Stockton Residents Past,
Present,
Future
Activities in yard.
Gardening.
437 total
26 children
Lead
Arsenic
Ingestion of Produce Eating produce from home garden.
Inhalation of Contaminated Dust Wind blown dust.


Table 4.

Exposure and Demographic Table
Pathway Name Unknown Estimated Pop. in Pathway Range Minimum Range Maximum
a. Pot. Pathways On-site  

437
(26 children 0-6 years of age)

400
22 children

500
80 children

b. Pot. Pathways Off-site   0 0 0
c. Total Pot. On and Off-site   0 437
(26 children 0-6 years of age)
400
22 children
500
80 children
d. Compl. Pathways On-site   437
(26 children 0-6 years of age)
400
22 children
500
80 children
e. Compl. Pathways Off-site   0 0 0
f. Total Compl. On and Off-site   437
(26 children 0-6 years of age)
400
22 children
500
80 children
g. Pot and Compl. Pathways On-site   437
(26 children 0-6 years of age)
400
22 children
500
80 children
h. Pot and Compl. Pathways Off-site   0 0 0
i. Total Pot. And Compl. On and Off-site   437
(26 children 0-6 years of age)
400
22 children
500
80 children


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