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The proposed National Zinc Company (NZC) NationalPriorities List (NPL) Site is located inthe City of Bartlesville in Washington and Osage Counties, Oklahoma. The proposed NPL siteincludes all of the lead- and cadmium-contaminated land within a several mile radiussurrounding the Zinc Corporation of America facility. A primary cause of the lead and cadmiumsoil contamination is the past emissions produced by the NZC and other smelting operationsconducted at the current location of the Zinc Corporation of America facility.

Based on the available information, the Agency for Toxic Substances and Disease Registry (ATSDR) concludes that the proposed NZC NPL site is a public health hazard becauseindividuals are being exposed to cadmium, lead, and zinc surface soil contamination at levelsthat could result in adverse health effects. Children are more likely than adults to ingest surfacesoil contamination. Blood lead studies have demonstrated that the children living in the area ofsurface soil contamination have higher blood lead levels than children living outside the area ofcontamination. Individuals who are exposed to the surface soil contamination may experienceproteinuria (i.e., protein in urine, which is evidence of mild kidney damage); decreasedmetabolism of vitaminD; impaired hearing and growth; and slightly lower IQs. Remediation ofthe contaminated soils should remove this public health hazard.

Environmental monitoring studies conducted in the past indicate that individuals could havebeen exposed to cadmium, lead, zinc, and sulfuric acid at levels that could result in adversehealth effects. Blood cadmium and blood lead studies conducted in the 1970s revealed thatchildren living near the smelter were exposed to elevated levels of cadmium and lead. Individuals who were exposed in the past to the air emissions from the smelter and to the surfacesoil contamination could have experienced decreased hemoglobin synthesis, anemia, increasedblood pressure, impaired hearing and growth, slightly lower IQs, and encephalopathy. Cadmiumair emissions from the historical smelter operations could have increased the risk of developingcancer for lifetime residents of Bartlesville. exposure to sulfuric acidair emissions could haveresulted in irritations of the eye, nose, throat, lung, and skin at the time of exposure, but does not pose a current threat to the health of individuals in this area.

Analysis of samples taken from groundwater monitoring wells on and near the ZincCorporationof America facility indicate that the groundwater contamination found on the facility has notmigrated very far. No drinking water wells are known to exist within the area of contamination. Therefore, it is unlikely that any drinking water wells have been contaminated with facility-relatedmetals.

Results of ambient-air monitoring dataindicate that the interim dust control measures at theresidual piles are preventing significant air emissions. ATSDR scientists are concerned that airemissions from the residual piles at the Zinc Corporation of America could occur whenever thepiles are disturbed or the interim measures are not continued.

ATSDR recommends the following actions:

ATSDR recommends the following actions:
1)Continue to clean up the contaminated soils in residential areas.
2)Continue to control air emissions from the residual piles.
3)Evaluate adverse health outcomes that could be related to past exposures.
4)Conduct a thorough review of all health outcomedata bases (i.e., cancer registry, birthdefects registry, and birth weight records) as the data becomes available.
5)Educate community members and health professionals on the nature and possibleconsequences of exposure to contaminants at theproposed NZC NPL site.


A. Site Description And History

The proposed National Zinc Company (NZC) National Priorities List (NPL) Site is located inthe City of Bartlesville in Washington and Osage Counties, Oklahoma. The proposed NPL siteincludes all of the lead- and cadmium-contaminated land within a several mile radiussurrounding the Zinc Corporation of America facility (see Appendix 1, Figure 1). A primarycause of the lead and cadmium soil contamination is the past emissions produced by the NZCand other previous smelting operations conducted at the current location of the Zinc Corporationof America facility (1).

NZC began operations at the site in 1907, primarily to recover metals such as zinc, cadmium,and lead from industrial materials. NZC used smelting and chemical processing to recover themetals. In addition to the NZC smelter, a vanadium smelter (closed in the mid-1980s) and twoother zinc smelters (closed in the 1920's) have operated on the land that presently encompassesthe current Zinc Corporation of America facility. Zinc Corporation of America purchased NZCin 1987 and continued recovery operations (1).

The only emission control used by the NZC smelter prior to 1969 was a limited sulfuric acidrecovery operation built in 1927. A more efficient acid recovery operation, which greatlyreduced the sulfur dioxide emissions, replaced the old sulfuric acid recovery plant in 1969. An electrostatic refining process that replaced the NZC horizontal retort furnaces in 1976 greatly reduced particulate stack emissions (1).

From 1975 through 1985, the community surrounding the former NZC smelter was thesubjectof five major studies. Baker et al. published "Nationwide Survey of Heavy Metal absorption inChildren Living near Primary Copper, Lead, and Zinc Smelters" in the American Journal ofepidemiologyin 1977 (2). The data for this study were collected in 1975. Lead and cadmiumlevels were determined in 1,744 children, 1-5 years old, living in 19 U.S. towns. Childrenselected from towns not containing smelters were used as controls. The evaluation includedanalyses of blood, urine, and hair for metals. The Baker et al. study indicated that children inBartlesville had the highest mean blood cadmium, hair cadmium, and blood lead levels amongthose evaluated.

The U.S. Environmental Protection Agency (EPA) and Research Triangle Institute conductedaseparate study, "Epidemiological Study Conducted in Populations Living Around Non-ferrousSmelters," in 1977 (3). This study confirmed that blood lead levels in Bartlesville children wereabove safe levels.

Blood lead studies were conducted by Environmental Consultants Laboratory fromSeptember1977 to December 1979 as a part of a class action law suit against the owners of the NationalZinc Smelter (4). Blood samples were obtained from 169 individuals (children and adults) whoresided within 1.6 kilometers (approximately 1 mile) of the smelter. This study also confirmedthat blood lead levels were high in people living next to the smelter.

Two studies (1979 and 1980) evaluated the soil concentrations ofmetals in the Bartlesvilleschool yards. Both studies found elevated concentrations of lead and cadmium in surface soiland dust in the school yards and schools (greater than 500 milligrams of lead per kilogram ofsoil [mg/kg] or greater than 30 mg/kg of cadmium) (5,6).

A 1985 doctoral dissertation by a University of Oklahoma student evaluated the health risksassociated with the lead and cadmium environmental contamination of air, water, soil, and paintin the Bartlesville area (4). This study concluded that residents of census tract 0002, directlynorth of the smelter, had the highest potential for exposure to elevated levels of lead andcadmium. The study also concluded that children within census tract 0002 represented thehighest risk group.

In May 1991, the Oklahoma State Department of Health (OSDH) asked the Agency for ToxicSubstances and Disease Registry (ATSDR) to evaluate the public health threats posed byexposures to metals believed to be in the community surrounding the old NZC smelter (1). ATSDR issued a health consultation for NZC in July 1991. The ATSDR Health Consultationconcluded that the lead and cadmium soil concentrations found at schools and residential areaswere a potential public health concern. ATSDR recommended that the extent of metalcontamination be characterized, biomedicalmonitoring be considered, and community healtheducation programs be provided to the residents and the local medical community.

In November 1991, EPA began an accelerated cleanup program at the proposed NZC NPLsite. The first step in the accelerated cleanup program was characterizing the extent of metalcontamination around the former NZC site (Phase I) by taking screening samples within a36-square-mile area (centered around the former NZC site) (7). One-square-mile grids wereformedout of the 36-mile area and at least one surface soil (top three inches of soil) grab sample wastaken from each grid. These samples were analyzed for 24 target metal compounds, and theresults indicated that lead and cadmium were elevated and warranted more extensive evaluation.

During the Phase II characterization and removal action, EPA took surface samples from 54highaccess areas (playgrounds, schools, and day-care centers) (7). The results of these samplesindicated that 29 of the 54 candidate high access areas had at least one sample above EPA'saction levels established for emergency removal purposes (500 mg/kg for lead and 30 mg/kg forcadmium). In addition to the high access areas, other locations were also sampled to determinethe nature and extent of lead and cadmium contamination. These other locations were residencesat which elevated blood lead levels were detected in resident children. The results of these twoassessments prompted EPA to remove contaminated surface soil from the 25 high access areasand 10 residences.

In August 1992, EPA conducted Phase III of the cleanup program. About 2,000 soil samplesfrom the surface down to 24 inches were collected at specific grid locations to verifythe extent of metals contamination across Bartlesville and the surrounding area (8). As part of Phase III, soil samples were collected from yards of 22 residences occupied by children withblood lead levels of 10 micrograms of lead per deciliter of blood (µg/dL) orgreater.

While EPA was conducting the Phase I and II site characterization and removal actions,ATSDRfunded OSDH (now the Oklahoma Department of Environmental Quality [ODEQ]) to performblood lead studies (biomedical monitoring) (9). The studies' results indicate that blood leadlevels in children are higher in the area where soils contain high levels of lead. A more detaileddiscussion of the blood lead studies is presented in the Health Outcome Data Evaluation section of this Assessment.

In addition to funding the blood lead studies conducted by OSDH, ATSDR also sponsored aseminar to educate physicians. Dr. Roy DeHart, Director of the Division of Occupational andEnvironmental Medicine, University of Oklahoma Health Sciences Center, discussedimplications of lead exposure when he spoke to about 50 people at the meeting of theWashington County Medical Society February 12, 1992. Also during 1992, Dr. Edd Rhoades,Chief, Child Health and Guidance Services, OSDH, conducted medical education regarding leadexposure to children.

EPA proposed listing the NZC site on the NPL in May 1993 (7). On March 15, 1994, EPAapproved the State Pilot Delegation Program (10). The program transferred the administrationof the remediation of the site from EPA to ODEQ. This program is being undertaken in lieu offinalizing the NZC site on the NPL. Also on March 15, 1994, ODEQ and the PotentiallyResponsible Parties (PRPs) signed a Consent Agreement and Final Order.

The Phase III removal action began in March of 1994 (7). This action is being conducted bythePRPs. The removal action will focus on residences with surface soil contamination of greaterthan 1,500 mg/kg for lead and/or 90 mg/kg for cadmium. These levels are three times EPA'saction levels of 500 mg/kg for lead and/or 30 mg/kg for cadmium. As in the initial removals, allsoil above the action levels will be excavated in 6-inch increments down to a maximum depth of24 inches. To date, 263 residential yards have been remediated.

A Remedial Investigation/Feasibility Study (RI/FS) prepared by the PRPs was made availableto the public on July 1, 1994. The RI/FS was finalized on September 1, 1994 (11).

On December 13, 1994, ODEQ issued a Record of Decision (ROD) for the first operable unitforthe proposed NZC NPL site (10). The first operable unit addresses the portions of the site thatare most likely to impact human health. The function of this operable unit is to reduce the risksto human health associated with exposure to the contaminated materials. The major componentsof the selected remedy outlined in the ROD include:

  • removal and disposal of contaminated soils (arsenic concentrations higher than 60 mg/kg, cadmium concentrations higher than 100 mg/kg, or lead concentrations higher than 925 mg/kg) followed by restoration of yards in residential areas;
  • implementation of a program to monitor blood lead levels throughout (annually) and after the remedial action (comprehensive studies 2 years and then 5 years after completion of the remedial action) in the affected community; and
  • removal, tilling, capping, and/or treatment of contaminated soils (arsenicconcentrations higher than 600 mg/kg, cadmium concentrations higher than 200mg/kg, or lead concentrations higher than 2,000 mg/kg) in commercial andindustrial areas.

In the future, ODEQ will issue a ROD for the second operable unit for the proposed NZCNPLsite (10). The second operable unit will address any undue risks the site poses to environmentalreceptors.

In order to address the contamination at the former NZC facility, EPA issued a ResourceConservation and Recovery Act (RCRA) corrective action order on August 26, 1993. The orderrequires the owners of the Zinc Corporation of America facility to develop and implement acleanup plan for the environmental (e.g., soil and groundwater) contamination at the facility(12). To date, the owners of the Zinc Corporation of America facility have conducted ambientair monitoring near the residue piles and groundwater monitoring at and near the facility (13,14). In addition, the owners have instituted dust suppression measures at the residue piles and areexpediting closure of two surface impoundments at the facility (13).

B. Site Visit

A site visit was conducted by ATSDR staff (Sven E. Rodenbeck and Dr. John Crellin fromtheDivision of Health Assessment and Consultation, Superfund SiteAssessment Branch, andJennifer Lyke and Roberta Erlwein from the ATSDR Region VI Office) on October 26 - 28,1993, to collect information for the Public Health Assessment for the proposed NZC NPL Site(Update 14). Public Availability Sessions were held on October 27. In addition, meetings wereheld with EPA; ODEQ; Citizens Against Toxics (CAT), a local citizens' group; the City ofBartlesville; representatives of various other organizations; and other individuals.

The following observations were made during the site visit:

-During the site visit, the Zinc Corporation of America smelter was notoperational while modifications to the plant were being conducted andactivities associated with the RCRA corrective action order were beingimplemented.

-The Zinc Corporation of America facility has approximately 77structures (manufacturing buildings, offices, etc.) and 5wastewater impoundments. It is totally surrounded by an 8-footchain-link fence and is patrolled by security guards 24 hours perday. The impoundments are reported to range in size from 10,000square feet to 687,500 square feet. There are several waste piles atthe facility. The largest is a pile of goethite, which may includecadmium, copper, lead, zinc, manganese, cobalt, and iron, and thepile is reported to contain 4 million cubic feet of material.

-The Phillips Research Center is located across State Road 123directly west of the Zinc Corporation of America facility.

-Most of the contaminated areas are residential areas. Lower costresidential areas are near the smelter.

In addition to a general site survey, the ATSDR staff visited most of the high access areas thathave been remediated by EPA.

During the publiccomment Period (September 21, 1994 through November 20, 1994) for thispublic health assessment, ATSDR staff (Sven E. Rodenbeck, Dr. John Crellin, and Ms. JenniferL. Lyke) held a Public Meeting on October 13, 1994. The meeting permitted the public todiscuss the public health assessment in an open forum. During the Public Comment Period,comments concerning this public health assessment were given verbally and were submitted inwriting. In addition, meetings were held with ODEQ, CAT, and the City of Bartlesville. Thepublic comments along with ATSDR's responses are summarized in Appendix 5.

C. Demographics, Land Use, And Natural ResourceUse

1. Demographics

Bartlesville is the county seat for Washington County and has a population of about 46,700. The three major employers in the city are Phillips Petroleum Company, Zinc Corporation ofAmerica, and Reda Camco Incorporated (a pump manufacturer). The National Institute forPetroleum Energy Research is also located in Bartlesville.

According to 1990 census data, Washington County's population was approximately 48,800(91.2 percent white, 2.6 percent black, and 6.2 percent other; 59 percent male and 41 percentfemale). Children (0-9 years old, 51.4 percent male and 48.6 percent female) made up 14.3percent of the Washington County population in 1990.

2. Land Use

The largest portion of the land area on the proposed NPL site is residential. Some of theresidences have gardens. Three elementary schools and 10 day-care centers are also locatedwithin the proposed NPL site. Most of the properties directly bordering the Zinc Corporation of America facility are zoned for industrial use.

Most of the unzoned areas north and west of Bartlesville are used for agricultural purposes. Agricultural products that are commonly grown or raised in the Bartlesville area include beefcattle, horses, hogs, sheep, soybeans, wheat, sorghum, corn, and alfalfa.

The Prairie National Wild Horse Refuge is located a few miles southwest of Bartlesville. Itwasestablished in 1989 and covers more than 18,000 acres. A Bison Refuge is north of Bartlesville.

3. Natural Resource Use

Surface runoff from the Zinc Corporation of America facility is primarily towards the south. Two tributaries (North and West) of Eliza Creek collect the surface runoff. These tributariescombine and flow into Eliza Creek approximately 4,000 feet south of the facility. Eliza Creekcombines with Sand Creek and they discharge into the Caney River south of the City ofBartlesville. Fishing may be conducted in Eliza and Sand Creek. In addition, the flood plain ofSand Creek is actively mined for sand. The Caney River flows through the center of Bartlesvilleand is used for recreation and fishing.

Lake Hudson and Lake Hulan, north of the NZC site, supply the Bartlesville drinking water. The lakes are not within the drainage basin of the proposed NPL site. According to EPA, nowells within a three mile radius of the former NZC facility are used for drinking water.

D. Health Outcome Data

ATSDR selects health outcomes for further evaluation from health outcome databases thathaveinformation on the area near the site. Oklahoma has a cancer incident registry and a birth defectregistry.

Cancer and birth defects could be plausible health outcomes from exposure to lead andcadmium. Please refer to the Toxicologic Evaluation subsection for more detailed information.

In addition to the health databases maintained by OSDH, the National Center for HealthStatistics, Centers for Disease Control and Prevention (CDC), maintains vital statisticsinformation (birth and mortality records) for the various counties in the U.S. Mortality statisticswere obtained for Washington County for the years 1979 through 1988.


During the October site visit, the Agency for Toxic Substances and Disease Registry(ATSDR)staff members determined the community health concerns via conversations with localgovernment officials, U.S. Environmental Protection Agency (EPA) officials, OklahomaDepartment of Environmental Quality (ODEQ) officials, members of Citizens Against Toxics(CAT), and individual citizens (during the public availability sessions). The residents andofficials raised the following health-related concerns:

  1. Is the cancer incidence (as the result of occupational and environmental exposures) in the Bartlesville area elevated?
  2. Is the incidence of birth defects in the area elevated? If so, could the increased incidence be caused by the same causes producing birth defects in horses born near the smelter before the smelter used pollution control devices ("smelter colts")?
  3. Are behavioral problems of children in the area related to the environmental contamination?
  4. Is Multiple Sclerosis (MS) caused by lead and/or cadmium?

The Community Health Concerns Evaluation section of this Public Health Assessmentaddressesthese concerns.

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