PUBLIC HEALTH ASSESSMENT
NATIONAL ZINC COMPANY
BARTLESVILLE, WASHINGTON COUNTY, OKLAHOMA
Because the proposed National Priorities List (NPL) site incorporates the Zinc Corporation ofAmerica facility and all of the known site-related lead and cadmium surface soil contaminationin Washington and Osage Counties, there is no "off-site" contamination. Therefore, this PublicHealth Assessment does not contain a separate section or discussion of "off-site" contamination. This section of the Public Health Assessment is divided into two subsections. The firstsubsection discusses the environmental contamination found on the Zinc Corporation of Americafacility. The second subsection is concerned with any environmental contamination found in thecommunity surrounding the Zinc Corporation of America facility which could have originatedfrom National Zinc Company (NZC).
In order to determine what environmental contaminants may be a concern, the Agency for ToxicSubstances and Disease Registry (ATSDR) has evaluated all of the available environmentalmonitoring data (1971 through 1994). Comparison values were used as a basis for evaluation ofthe data and to determine which contaminants should be looked at more closely. Comparisonvalues are estimated health-based environmental concentrations below which no known oranticipated adverse effect on the health of persons should occur. The values allow an adequatemargin of safety. Appendix 2 contains descriptions of the comparison values used in this Public Health Assessment.
A contaminant is selected for further evaluation if the contaminant concentration in a validenvironmental sample exceeds comparison values. The presence of a contaminant on the lists inthe tables of this section does not mean that either exposure to the contaminant or adverse healtheffects has occurred or will occur. Inclusion in the list indicates only that the potential forhuman exposures to the selected contaminants and the potential for adverse human health effectsas a result of any exposures to the selected contaminants will be discussed in more detail in latersections of this Public Health Assessment.
1. Environmental Contamination at the Zinc Corporation of America Facility
Ecology and Environment, Inc., inspected the facility on June 2-4, 1981, for EPA (15). Waterand soil samples were collected to assess the extent of contamination at the facility. A surfacewater and sediment sample was taken from Reservoir A, one of the five wastewaterimpoundments. A groundwater sample was taken from each of the four monitoring wells at thefacility. Soil samples (depths not provided) were collected at three locations. Additionalsamples (depths not provided) were collected from the residue piles at the facility. No volatileor semi-volatile organic compounds were detected at levels above comparison values in any ofthe samples.
On November 12-13, 1991, U.S. Environmental Protection Agency (EPA) personnel conducteda compliance evaluation inspection (CEI) at the Zinc Corporation of America facility (12). Eighteen samples were taken at the residue piles. During the CEI, the inspectors observed thatthe piles were marked on all sides by erosion patterns and surrounded by water which remainedfrom a recent rain.
On February 18, 1992, the owners of the Zinc Corporation of America facility sampled thegroundwater under the facility from 36 groundwater monitoring wells (12). These samples wereanalyzed for total metals (arsenic, antimony, barium, beryllium, cadmium, chromium, cobalt,copper, lead, mercury, mercury, nickel, silver, selenium, thallium, tin, vanadium, and zinc). The results of the analyses were reported in the Resource Conservation and Recovery Act (RCRA)permit application submitted by the owners of the Zinc Corporation of America facility.
As required by the EPA RCRA corrective action order of August 1993, the present owners of theZinc Corporation of America facility have conducted ambient air monitoring near the residuepiles and have investigated whether the groundwater metal contamination found at the facilityhas migrated off the facility (13,14). The results of the ambient air monitoring indicates that theinterim dust suppression method is preventing any significant emissions from the residue piles. The groundwater monitoring investigation indicates that some of the groundwater contaminationat the facility has migrated towards the south and northwest (arsenic <0.002-0.012 milligrams ofarsenic per liter of water [mg/L], <0.02-0.3 mg/L of lead, <0.01-0.03 mg/L of nickel, and 0.4-12.8 mg/L of zinc). Some of the metal concentrations found just off the facility are above healthcomparison values (0.00002 mg/L for arsenic, 0.007 mg/L for cadmium, 0.1 mg/L for nickel,and 3.0 mg/L for zinc; there is not a health comparison value for ingesting lead). However, theconcentration of metals in groundwater off the Zinc Corporation of America facility aresignificantly less than that found on the facility.
No stack monitoring (air emission) data is available for the NZC facility. It has been estimatedthat the facility discharged approximately 1,500 tons (3 million pounds [lbs]) of particulatematter per year before 1976 (7). A review of the EPA Toxic Chemical Release Inventory (TRI)database indicates Zinc Corporation of America released an average of 3,429 lbs of lead, 1,474lbs of cadmium, and 23,600 lbs of zinc into the air each year from 1987 to 1991 (17).
NZC also discharged sulfur dioxide to the ambient air (16). In July 1977, a major malfunction occurred at the NZC sulfuric acid recovery plant. This malfunction resulted in
|* - This indicates only one environmental sample was taken.|
** - See Appendix 2 for a description of the comparison values and their sources.
mg/L - milligrams of contaminant per liter of water, mg/kg - milligrams of contaminant per kilogram of soil, µg/m3 - micrograms of contaminant percubic meter of air, NR - not reported or analyzed.
significantly more sulfur dioxide being discharged than was regularly discharged. Once releasedto the ambient air, sulfur dioxide converts to sulfuric acid. Residents near the plant reported tothe EPA that vegetation damage and human respiratory damage occurred because of themalfunction. From July 28 through September 26, 1977, EPA monitored the ambient airsurrounding NZC. Based upon this investigation, EPA concluded that the July incident occurredbecause of operator error. Long-term emissions from NZC (not just the one event) may havedamaged local plants, and certain metals (i.e., lead, zinc, iron, and copper) were found toincrease in the ambient air downwind from the plant.
2. Environmental Contamination found in the Surrounding Community
Environmental sampling of surface soil, drinking water, ambient air, and sediment has beenconducted in the community surrounding the current Zinc Corporation of America facility sincethe late 1970s. Table 2 presents results of the historical sampling efforts by EPA and others(1977-1982) (3-6), while Table 3 presents the results of the most current EPA environmentalsampling effort (Phases I, II, and III) (18-20). Also included in Table 3 are the results of the Remedial Investigation conducted by the Potentially Responsible Parties (11).
During the current EPA surface soil sampling effort, cadmium was detected 12.6 percent of thetime (167/1324) above the action level (30 milligrams of cadmium per kilogram of soil[mg/kg]), while lead was detected in surface soil samples 12.1 percent of the time (160/1324)above the action level (500 mg/kg). The spatial distribution of these metals is coincident with apoint source air emission (i.e., the highest levels detected are nearest the former NZC smelterand the surface soil contamination is downwind of the facility) (18).
In addition to comparing the detected concentrations of metals found in surface soils to healthbased comparison values, it is also prudent to identify whether the detected levels are within theranges for background or normal soil levels, especially when only a limited number of the soillevels are above the comparison value. According to the U.S. Geological Survey, the typical soilbackground levels of arsenic, nickel, and zinc are <0.1 to 97 mg/kg, <5 to 700 mg/kg, and 10 to2,100 mg/kg, respectively. Arsenic was detected above the maximum background level of 97mg/kg in only 1.6 percent (23/1421) of the samples analyzed in 1991-1992. Because arsenic hasbeen used in various commercial products (e.g., pesticides) and the spatial distribution of theelevated arsenic results is not coincident with air emissions from the NZC facility; the arsenicfound in the Bartlesville residential soils does not appear to be a site related contaminant. (Note: Arsenic is found at the facility in the soil and residue piles). Because nickel was not detectedabove background levels in residential surface soils, this metal is not considered to be a siterelated contaminant. Zinc was detected above background levels in 19.6 percent (260/1324) ofthe samples taken in 1991-1992. In addition, the spatial distribution of zinc is coincident with apoint source air emission coming from NZC. Therefore, zinc should be considered a site-relatedcontaminant.
|* - See Appendix 2 for a description of the comparison values and their sources.|
mg/kg - milligrams of contaminant per kilogram of soil
mg/L - milligrams of contaminant per liter of water
µg/m3 - micrograms of contaminant per cubic meter of air
NR - not reported or analyzed
|* - See Appendix 2 for a description of the comparison values and their sources.|
mg/kg - milligrams of contaminant per kilogram of soil
mg/L - milligrams of contaminant per liter of water
µg/m3 - micrograms of contaminant per cubic meter of air
NR - not reported or analyzed
During the Remedial Investigation, 4 surface soil samples were taken from gardens located inthe area of Bartlesville with the highest surface soil contamination (south of West HensleyBoulevard and west of Short Avenue ) (11). Analytical results of these samples found 3.7 to12.9 mg/kg of arsenic, 3.2 to 66.6 mg/kg of cadmium, 65.4 to 339 mg/kg of lead, and 564 to6,680 mg/kg of zinc. Surface soil samples were also taken from 12 gardens in Oak Park Village. Analytical results of these samples found 2.6 to 9.3 mg/kg of arsenic, 0.7 to 11.4 mg/kg ofcadmium, 11.2 to 194 mg/kg of lead, and 86.9 to 1,020 mg/kg of zinc.
Surface water and sediment samples were taken from drainage ditches, the North Tributary, andthe West Tributary through which storm water from the Zinc Corporation of America facilityflows (11,18). In addition, surface water and sediment samples were taken from the ElizaCreek, the Sand Creek, and the Caney River. Analytical results of the samples indicate thatarsenic, cadmium, lead, and zinc are present in the ditches, tributaries, and creeks abovebackground levels. Most of the high concentrations of these contaminants were found in thedrainage ditches, the North Tributary, and the West Tributary near the facility. The highestconcentrations were found in the North Tributary. Analytical results of samples taken from theSand Creek and the Caney River indicate that arsenic, cadmium, lead, and zinc are atbackground levels within these bodies of water.
EPA has conducted two ambient air monitoring studies in the community surrounding NZC. The first study was conducted shortly after the major malfunction at NZC in 1977 (16). Theanalytical results of samples taken indicated that the air contained cadmium at concentrations ofless than 0.03 micrograms of cadmium per cubic meter of air (µg/m3) (the analytical detectionlimit) to 0.26 µg/m3 downwind of NZC. Lead was detected at 0.17 µg/m3 to 2.5 µg/m3 duringthe 1977 study.
The second EPA ambient air monitoring study was conducted in 1992. This study foundcadmium and lead concentrations of less than 0.002 to 0.61 µg/m3 and 0.05 to 6.8 µg/m3respectively (16). However, the highest level of cadmium detected (0.61 µg/m3) was invalidatedbecause the location where this sample was taken was more representative of street dust thanambient air concentrations.
The City of Bartlesville Water Department has taken 135 drinking water tap samples (1992-1993). All of these samples were taken without flushing the standing water from the householdpipes (first draw). The Oklahoma State Environmental Laboratory analyzed all of the samplesfor lead. According to the laboratory analysis, only 2 of the 135 tap samples (1.5 percent)contained lead above the laboratory detection limit of 0.005 mg/L (0.035 and 0.007 mg/L). Both of these drinking water taps had been sampled previously. Analytical results for theprevious sampling period did not find lead above the laboratory detection limit of 0.005 mg/L(20). The two samples containing lead above detection levels probably represent lead pipesolder within those homes and not site-related contamination.
The City of Bartlesville Water Department also takes drinking water samples to determinewhether the city drinking water contains any chemicals above the EPA Safe Drinking Water ActMaximum Contaminant Levels. Analysis of these samples was conducted by the OklahomaState Environmental Laboratory. The analytical results indicate that there are no chemicals inthe City of Bartlesville drinking water above health comparison values (20).
ATSDR was able to obtain quality assurance and quality control (QA/QC) information for mostof the data presented in this Public Health Assessment. This information indicates appropriateQA/QC was performed for the samples. The conclusions presented in this Public HealthAssessment are based in part on the data presented. The validity of the conclusions, therefore,depends on the accuracy and reliability of the data provided.
No physical or other hazards, except those normally found at an industrial facility or residentialarea, were noted during the ATSDR site visit.
To identify possible facilities that could contribute to the surface soil contamination inBartlesville, ATSDR searched the 1987 to 1991 files of the Toxic Chemical Release Inventory(TRI) databases for the zip codes where the site is located (74003, 74004, 74005, and 74006)(17). TRI was developed by the EPA from chemical release information (air, water, and soil)provided by certain industries.
Several limitations of TRI data should be noted (21). The air release data in TRI may beestimates or actual measurements. Many of the reported data are estimates based onconservative (overestimated) scenarios. Consequently, the levels of emissions recorded in TRIare often biased on the high side. In addition, reporting is restricted to specific chemicals thatare used or released above specified amounts. Finally, it is believed there have been and still areindustries that do not report releases. Smaller industries may not be aware that reportingrequirements exist or that they are responsible for such reports.
The search of TRI indicates that four facilities within the selected zip codes have dischargedchemicals to the environment (17). Only Zinc Corporation of America and B&WMicronutrients reported discharging any of the chemicals identified in this Public HealthAssessment. As previously discussed, Zinc Corporation of America released to the air anaverage of 3,429 lbs of lead, 1,474 lbs of cadmium, and 23,600 lbs of zinc each year for theyears 1987 to 1991. B&W Micronutrients reported releases to the air of an average of 2,025 lbsof zinc each year for the years 1988 to 1991. These air releases should not contributesignificantly to the surface soil contamination in Bartlesville.
In this section of the Public Health Assessment, the possible environmental exposure pathwaysare evaluated to help determine whether individuals have been, are being, or will be exposed tosite-related contaminants. The pathway analysis consists of five elements:
- identifying contaminants of concern possibly related to the site;
- determining that contaminants have been, are being, or will be transported through an environmental medium;
- identifying a point of exposure (i.e., a place or situation where humans might be exposed to the contaminated media);
- determining that there is a plausible route of human exposure (i.e., can the contaminant enter the body?); and
- identifying an exposed population (i.e., how many people, if anyare at the point of exposure?).
An environmental exposure pathway is considered complete when there is good evidence that allfive elements exist (22). The presence of a completed pathway indicates that human exposure tocontaminants has occurred in the past, is occurring, or will occur in the future. When one ormore of the five elements of an exposure pathway are missing, that pathway is consideredpotential. The presence of a potential exposure pathway indicates that human exposure tocontaminants could have occurred in the past, could be occurring, or could occur in the future. An exposure pathway can be eliminated from consideration if at least one of the five elements ismissing and will never be present. If there is uncertainty about the site-relatedness of thecontaminants of concern in an exposure pathway, the pathway will be evaluated as if thecontaminants were site-related.
The completed environmental exposure pathways, the potential environmental exposurepathways, and the specific pathways eliminated from consideration are discussed below. Inaddition, Appendix 3, Tables 1 and 2, present the estimates of the number of exposed individualsat the proposed NZC NPL site. The population estimates are based upon the informationcontained in the EPA Hazard Ranking System Report for the proposed NZC NPL site (thenumber of residences within an one mile-radius from the facility) (23).
There is good evidence that people have been, are being, and will continue to be exposed tosurface soil contamination through ingestion, inhalation, and skin contact at the proposedNational Zinc Company (NZC) National Priorities List (NPL) site (the "Surface Soil" pathway). In addition, people have been exposed to direct ambient air discharges from past operations atthe NZC facility through inhalation, ingestion, and skin contact (the "Air" pathway).
1. Surface Soil
Analysis of surface soil samples (0-3 inches) clearly demonstrates cadmium, lead, and zinccontamination at levels above health comparison values. The contaminated surface soil is foundat the Zinc Corporation of America facility and in the surrounding residential areas. Individuals,primarily children, will be exposed to the surface soil contamination via inadvertentconsumption and skin contact with the soil on hands or food items, mouthing of objects, or theingestion of nonfood items (pica). In addition, these individuals will inhale the soilcontaminants whenever the surface soil is disturbed (e.g., dust and particulate matter). Allchildren mouth or ingest nonfood items to some extent. The degree of pica behavior varieswidely in the population, and is influenced by nutritional status and the quality of care andsupervision. Groups that are at increased risk for pica behavior are children aged 1 to 3 yearsold, children from families of low socioeconomic status, and children with neurologic disorders(e.g., brain damage, epilepsy, and mental retardation).
Analysis of surface soil and residue pile samples at the smelter facility revealed cadmium, lead,and zinc contamination at higher levels than those found in the residential soils. Therefore theworkers at the smelter can ingest, inhale, and have skin contact with the surface soil and residuepile contamination.
The blood lead studies funded by the Agency for Toxic Substances and Disease Registry(ATSDR) and performed by the Oklahoma State Department of Health (OSDH and theOklahoma Department of Environmental Quality (ODEQ) in 1991 and 1992 clearly indicate thatblood lead levels in children are higher in the area where surface soils are contaminated withhigh levels of lead (see discussion in the Health Outcome Data Evaluation section). Thesestudies strengthen the determination that people have been, are being, and can be exposed tosurface soil contamination.
No stack monitoring data are available for the operational activities that occurred at NZC in thepast. However, it has been estimated that the facility smelter discharged approximately 1,500tons (three million pounds [lbs]) of particulate matter per year into the ambient air prior to 1976. The chemical makeup of the particulate matter would have included the metals detected in theresidue piles and in the residential soils (primarily cadmium, lead, and zinc). The 1977 and1992 ambient air monitoring indicated that cadmium and lead were being discharged into theambient air from the smelter. In addition, the magnitude of the air discharges is reflected by thevery high levels of surface soil contamination found at the facility and in the residential soils; theprimary cause of the residential soil contamination is air deposition of air discharges from thesmelters. Therefore, individuals working at the smelters and/or living near the NZC facilitywould have inhaled, ingested, and experienced skin contact with the particulate matter beingdischarged by NZC.
The 1975 and 1977 epidemiologic studies conducted in Bartlesville confirm that individualswere exposed to high levels of lead and cadmium (see discussion in the Health Outcome DataEvaluation section). These studies found that children in the Bartlesville area had higher bloodlead and cadmium concentrations than the concentrations of children who did not live near azinc smelter.
Since NZC changed the metal extraction process, the direct discharges to the ambient air havebeen greatly reduced. In addition, the facility attempts to mitigate the dispersion of metals fromthe residue piles by spraying the piles with a latex material.
Besides the particulate and metal discharges, NZC also discharged sulfur dioxide to the ambientair. The major malfunction that occurred at the NZC sulfuric acid recovery plant in July 1977resulted in significantly more sulfur dioxide being discharged than is regularly discharged. Oncereleased to the ambient air, sulfur dioxide converts to sulfuric acid. Residents near the plantreported to the U.S. Environmental Protection Agency (EPA) that vegetation damage and humanrespiratory damage occurred because of that malfunction. Based upon the July 28 throughSeptember 26, 1977, investigation, EPA concluded that the July incident occurred because ofoperator error; long term emissions from NZC may have damaged local plants; and certainmetals (i.e., lead, zinc, iron, and copper) were found to increase in the ambient air downwindfrom the plant. Therefore, it is likely individuals were exposed (i.e., via inhalation, ingestion,and skin contact) to elevated levels of sulfuric acid in the ambient air.
People could potentially be exposed to site-related contaminants via sediment, surface water andbiota. These potential pathways could have occurred in the past, could be occurring now, orcould occur in the future. In addition, the ambient air could become contaminated whenever theresidue piles at the Zinc Corporation of America facility or the contaminated subsurface soils(greater than 3 inches) are disturbed.
1. Sediment and Surface Water
Surface water runoff (storm water) and wastewater generated at the Zinc Corporation ofAmerica facility are retained and treated (sedimentation) in the facility impoundments anddisposed of via two permitted injection wells. Under normal operational conditions no surfacewater or sediment from the facility should move off-site. However, the owners of the facilityhave reported off-site releases of storm water runoff because of overtopping of theimpoundments during storms. Nine releases have been reported to the Oklahoma WaterResources Board (eight from 1985 to 1987 and one on May 4, 1991).
Analysis of surface water and sediment samples from one of the facility wastewaterimpoundments and one of the ditches on the facility indicates that arsenic, cadmium, lead,manganese, nickel, and zinc could migrate beyond the facility boundaries. Analysis of sedimentsamples taken in the ditches, the North Tributary, and the West Tributary near the facilityindicates that cadmium, lead, and zinc have migrated beyond the facility boundaries. Individualscould potentially be exposed to the sediment contamination via inadvertent consumption,inhalation, and skin contact with the sediment. Ingestion, inhalation, and skin contact with thesurface water contaminants could potentially occur during heavy storm. However, suchexposures are not likely to occur very frequently.
It is unlikely that the general public would be exposed to the contaminated sediment and surfacewater at the facility, because access to the facility is restricted. The total facility is surroundedby an 8-foot fence and is patrolled 24 hours a day. Workers could potentially ingest, inhale, or have skin contact with the sediment and surface water at the smelter.
Any plants grown in the soils contaminated with cadmium, lead, and zinc will have the tendencyto incorporate the metals in the plant tissue (uptake) (24-26). In general, metals may accumulateon plant surfaces as a result of atmospheric deposition of dust or particles containing the metals. The metals may enter plant tissues through absorption of particles that adhere to foliage surfacesand/or via active transport through the roots. The higher metal concentrations in plants arefound in the older parts of the plants.
During the October 1993 site visit, ATSDR staff members saw residential-area garden plots thatcould have high surface soil concentrations of cadmium, lead, and zinc. Analytical results ofsurface soil samples taken from garden plots within the affect areas of Bartlesville indicate thatthese gardens contain metal concentrations which are slightly elevated above back ground levels(11). These sampling results may be representative of present conditions. However, the metalconcentrations in the past may have been higher until the tilling of the soil and importation ofsoil amendments each season reduced the metal concentration in the garden plots. Any plantsgrown in these plots before the metal concentrations were reduced may have accumulated highercadmium, lead, and zinc concentrations than plants grown outside the contaminated area wouldaccumulate. Therefore, individuals ingesting or experiencing skin contact with these plants mayhave been exposed to the metals accumulated in the plants.
Fish can bioaccumulate cadmium, lead, and zinc (24-26). However, analysis of surface waterand sediment samples from Sand Creek and the Caney River indicate there is not any significantmetal contamination in these bodies of water (11). Some elevated levels of cadmium, lead andzinc were found in the Eliza Creek near the location where the North Tributary connects to theEliza Creek. Sand Creek and Caney River are used for recreational fishing. Some recreationalfishing may take place in the Eliza Creek, but not as frequently. Therefore, it is not likelyanyone would be exposed to any significant amount of metals from fish in the Eliza Creek, SandCreek, or the Caney River.
3. Residue Piles and Subsurface Soils
Because there are very high concentrations of metals in the residue piles (i.e., arsenic, cadmium,lead, manganese, nickel, and zinc) and in the residential subsurface soils (i.e, cadmium, lead, andzinc), these metals could be released to the ambient air as dust and particulate matter wheneverthe piles or soils are disturbed. During the October 19-20, 1992, site inspection, EPA personnelobserved particles being blown from some of the residue piles. Therefore, individuals (e.g.,workers) near the residue piles or residential soils whenever they are distributed couldpotentially inhale, ingest, and have skin contact with the dust and particulate matter and beexposed to the metals.
The 1993 Resource Conservation and Recovery Act (RCRA) corrective action order requires theowners of Zinc Corporation of America to design and implement procedures to prevent particlesfrom being blown from the residue piles (12). The owners of Zinc Corporation of America haveimplemented an interim dust suppression program. Analytical results of ambient air samplestaken near the residue piles indicate that the interim dust suppression program has significantlyreduced the emission of dust and particulate matter from the piles. Therefore, it is unlikelyanyone should be exposed to a significant amount of dust or particulate matter from the residuepiles; provided the dust suppression program continues to be implemented.
Two exposure pathways have been eliminated from consideration. These are human exposuresto site-related contaminants in drinking water and groundwater.
1. Drinking Water
Analysis of samples from the Bartlesville drinking water supply system (past and present) didnot detect any significant amounts of site related contaminants. Therefore, it is not likely thathumans were exposed to site-related contaminants by ingesting drinking water. The drinkingwater source for the City of Bartlesville is north of the proposed NPL site and is not likely to become contaminated as a result of the proposed NZC NPL site.
Analysis of samples taken from monitoring wells at and near the Zinc Corporation of Americafacility indicates that the groundwater directly under the facility is highly contaminated witharsenic, cadmium, lead, and manganese (i.e., above health comparison values) (12,13,14). Thecontamination has moved toward the northwest and south. However, this contamination doesnot appear to have migrated very far off the facility's property. According to EPA, no drinkingwater wells exist within a 3-mile radius of the facility. Therefore, it is unlikely that any drinkingwater wells have been contaminated with facility-related metals.
Lead is a naturally occurring element that has been used almost since the beginning ofcivilization. Because of the many industrial activities that have brought about its widedistribution, lead is ubiquitous in the environment today. All humans have lead in their bodies,primarily as a result of exposure to manufactured sources (25).
In addition to the emissions from the NZC plant, other environmental sources of metallic leadand its salts are paint, auto exhaust, and food. For Bartlesville children, the most importantpathways other than the smelter are ingestion of chips from lead-painted surfaces, inhalation oflead from automobile emissions (past exposure because lead is no longer used in gasoline), andfood from lead-soldered cans (past exposure because lead-solder is no longer used in food cans)(25).
The lead content of paint was not regulated until 1977. Many older structures, residential andcommercial, have leaded paint that is peeling, flaking, and chipping. Children can ingest loosepaint as a result of pica behavior and through mouthing of items contaminated with lead frompaint, dust, and soil. High levels of lead in soil and house dust have been associated withincreased blood lead levels in children (25). It has been estimated (based upon house paintsamples) that 29 percent of the homes in Bartlesville have interior lead paint (27).
In addition to the environmental sources, many occupations, hobbies, and other activities resultin potential exposures to high levels of lead and can put the entire family at risk of leadpoisoning (25). Plumbers, pipe fitters, printers, smelter workers, and battery manufacturingworkers can be exposed to lead at the work place. These workers can also bring the lead intotheir homes via dirty clothing. Hobbies and other activities which have the potential for highlead exposures include making glazed pottery, lead soldering (e.g., in electronics manufacturingor repair), making stained glass, and target-shooting at firing ranges. Lead-glazed pottery,particularly if it is imported, is a potential source of exposure that is often overlooked.
As discussed in the Pathways Analyses section, the surface soil and the ambient air exposurepathways are considered completed (i.e., human exposure has occurred or is occurring). Thecontaminants of concern are cadmium, lead, and zinc for the surface soil and ambient airpathways; in addition, sulfuric acid is a contaminant of concern for the ambient air pathway.
The Toxicological Evaluation portion of this section discusses the possible health hazard fromexposure to the contaminants of concern in surface soil and ambient air. Community healthconcerns are addressed in the Community Health Concerns Evaluation section, and healthoutcome data are discussed in the Health Outcome Data Evaluation section.
Typically, the toxicological evaluation in a public health assessment is a comparison of theestimated exposure dose (i.e., the amount of a substance individuals in an exposure pathway areexposed to daily) with an appropriate health guideline. The guideline is usually either theAgency for Toxic Substances and Disease Registry's (ATSDR's) Minimal Risk Level (MRL) orthe Environmental Protection Agency's (EPA's) Reference Dose (RfD). The MRLs and RfDsare estimates of daily human exposure to a contaminant below which noncarcinogenic adversehealth effects are unlikely to occur (22). That means that any exposure dose below theappropriate MRL or RfD does not represent a hazard to human health. However, for exposuredoses above an MRL or RfD, there is a significant degree of uncertainty about whether adversehealth effects will occur. Therefore, a review of the toxicological literature is done to determinewhether the specific exposure situation represents a hazard to public health. The results of thecomparison of exposure doses to health guidelines, and the methodology for calculating theexposure doses are described in Appendix 4.
In addition to evaluating those exposures where ATSDR was able to determine the level ofexposure (i.e., calculating an exposure dose), the possible health consequences of the 1977sulfuric acid incident is discussed.
There are no health guidelines for exposure to lead in soil, so the exposure doses for lead in thismedium can not be evaluated directly. However, blood lead concentrations do relate well topossible health effects (25). The blood lead studies conducted in the Bartlesville area arediscussed in the Health Outcome Data Evaluation section.
The adult, children, and pica children exposure doses for the maximum cadmium level in thesurface soil exposure pathway exceed the cadmium health guideline. The children and picachildren exposure doses also exceed the health guidelines for the maximum zinc level in thesurface soil exposure pathway, but the adult exposure doses do not. The possible healthconsequences of exposure to those chemicals which exceed the health guidelines are discussed.
For the ambient air exposure pathway, the air contaminant concentrations were compareddirectly to inhalation MRLs without any additional calculation. Cadmium in the ambient air ofthe surrounding community exceeded the inhalation health guideline. This result is discussed.
One of the three contaminants of concern, lead, is considered a probable human carcinogenwhen contacted through ingestion and inhalation routes, and another, cadmium, is consideredcarcinogenic only when contacted through the inhalation route (28). In the only relevant study,zinc has not been shown to cause cancer in one laboratory animal (26). EPA has not made adetermination as to whether zinc could potentially cause cancer in humans (28). There iscurrently no scientific data on how strong lead is as a cancer causing chemical (i.e., cancerpotency factor) (28). Therefore, only the risk of cancer because of exposure to cadmium couldbe evaluated.
2. The Possibility of Health Consequences
The possible health consequences of those exposure doses that exceeded health guidelines--cadmium and zinc--are described in the following paragraphs. Exposure to sulfuric acid is alsodiscussed.
Health assessors determine the possibility of health consequences by comparing the exposure tothe results of epidemiologic evaluations of human exposures to a chemical. If valid human dataare not available, information from properly conducted animal studies are used. The type ofdata used for an evaluation is indicated for each chemical.
Based on human data, there is some possibility of noncarcinogenic health effects for childrenexposed to cadmium in residential soil (24). Soil concentrations of cadmium of 375 mg/kg andgreater result in exposure doses for small children (10 kilograms [Kg]/22 pounds [lbs]) thatexceed the lowest observed effect level in humans of 0.0075 milligrams of cadmium perkilogram 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 15milligrams of cadmium per kilograms of soil (mg/Kg). Cadmium soil levels in the communityaround the Zinc Corporation facility vary from 0.2 through 1,372 mg/kg.
The lowest observed effect for ingestion of cadmium in humans is proteinuria, which is thedischarge of proteins from the kidney into the urine (24). Epidemiologic studies of individualsliving a lifetime in cadmium-contaminated areas in Japan, Belgium, and China identified rates ofproteinuria that were statistically greater than rates identified in uncontaminated areas. Proteinuria is considered a mild adverse effect on the kidney. Human studies do not identify adose where more serious kidney problems begin. Animal studies indicate this level may beabout 5 times greater than the exposure dose for small children with the habit of pica and 130times greater than for small children who do not ingest large amounts of dirt.
Other animal studies reveal that serious developmental and immunological effects begin to beobserved at 3 and 70 times greater than the exposure doses for pica children and small childrenrespectively (24). Because of animals' and humans' differences in responses to toxins, it ispossible that these more serious effects could occur.
Based on a study of workers exposed to cadmium for 30 years (not related to the National ZincCompany [NZC] or the Zinc Corporation of America facility), it is possible to conclude that aircadmium levels of 0.2 micrograms of cadmium per cubic meter of air (µg/m3) or greater couldcause mild damage to the kidney as evidenced by an increase in proteinuria (24). There is noambient air monitoring data during the historically high air emissions from the smelter. It hasbeen estimated that the facility discharged approximately 1,500 tons of particulate matter peryear before 1976. Given the high cadmium surface-soil contamination and the high levels ofcadmium measured in the blood and hair of people living near the smelter, it is possible that theambient air concentrations of cadmium near the smelter could have exceeded 0.2 µg/m3 for asignificant period of time.
Nine percent of the workers, in the aforementioned study, exposed to 23 µg/m3 of cadmium for30 years had proteinuria, while the usual rate of proteinuria in an unexposed population is 5%(24). Because those exposed were healthy workers, it is reasonable to conclude that moresensitive individuals, such as children or the elderly, could experience health effects. Whenthere are no data for those sensitive individuals, the effects level for the workers is adjusteddownward by a factor of 10. Measured air levels at Bartlesville of 0.2 µg/m3 or greater liewithin the zone of concern for sensitive individuals.
As described in the Environmental Contamination and Other Hazards section, the measurementof air cadmium levels was done after significant emission controls had been installed at thesmelter in 1977. Therefore, it is probable that exposure levels were higher prior to 1977, andthat the chance of adverse health effects due to cadmium was also higher, especially given themaximum exposure length of 70 years.
It is likely that residents of the area around the smelter are exposed to cadmium both throughingestion and inhalation and that those residents' risk of health effects would therefore begreater. Because there are differences in the way the body metabolizes inhaled versus ingestedcadmium, it is not possible to calculate what this greater risk might be.
Risk of Cancer
Evidence (i.e., the high surface concentrations of cadmium, the high particulate emission rate,and the high blood and hair cadmium levels in people) indicates that people living near thesmelter could have been exposed to high levels of cadmium in the ambient air. This exposurecould represent a moderate increase in the risk of cancer for residents around the smelter. Thecancer slope factor on which this conclusion is based comes from a study of cadmium smelterworkers (not related to NZC) exposed for 6 months to 29 years to dust and fumes from cadmiumand other metals (28). The study identified a two-fold increase in the rate of lung cancer. Othercauses of lung cancer, such as smoking or arsenic, were properly taken into account.
Based on human data, there is some possibility of noncarcinogenic health effects for childrenexposed to zinc in residential soil (28). Soil concentrations of zinc of 50,000 mg/kg and greaterresult in exposure doses for small children (10 Kg/22 lbs) that exceed the lowest observed effectlevel in humans of 1.0 mg/kg/day. For small children who ingest large amounts of soil (i.e., picachildren), the lowest effects level is exceeded when the zinc level exceeds 2,000 mg/kg. Zincsoil levels in the community around the Zinc Corporation facility vary from 13.7 through109,000 mg/kg.
The lowest observed effect for ingestion of zinc in humans is a 47% decrease in the level of theenzyme erythrocyte superoxide dismutase, which regulates the copper levels in the body (28). Along-term decrease in erythrocyte superoxide dismutase would result in a copper deficiency. Small children likely experience this effect at a higher dose than adults because childrenmetabolize zinc more slowly than adults. Therefore, children would need more zinc per unitbody weight than adults for this effect to occur. Zinc is an essential nutrient, and therecommended daily allowance for children, 10 milligrams of zinc per day (mg/day), is actuallythe same dose, 1 mg/kg/day, for a 10 Kg child as the lowest observed effect level seen in studiesof adults (29). Studies of adults indicate that it is unlikely that small children who do not havethe habit of pica (ingesting 5 or more grams of soil a day) would experience other health effects(28). Pica children ingesting soil contaminated with levels of zinc greater than 4,000 mg/kgcould possibly experience a decline in high-density lipoprotein levels, or impairment of immuneresponse. Because of the zinc metabolism differences between adults and children, it isuncertain that these health effects would occur in children.
c. Interactions Between Cadmium, Lead, and Zinc
Zinc is an essential element from the diet (26). However, there are no known benefits ofcadmium or lead (24,25). Many different metals (e.g., calcium) and nutrients interact with theabsorption, distribution, and excretion of cadmium, lead, and zinc. There is some evidence thatthese interactions may reduce the amount of cadmium, lead, and zinc absorbed into the body. Inaddition, cadmium, lead, and zinc compete for some similar target sites inside the body. Thiscompetition may result in decreased accumulation of cadmium in cells. If this occurs, the toxiceffects of exposure to cadmium would be reduced. There are some studies which indicate thatsimultaneous exposure to cadmium and zinc decreases the toxic effect of cadmium. In addition,zinc may have a protective effect against lead toxicity. However, some toxicological studiesindicate that simultaneous exposure to lead and cadmium increases the toxic effects. Asindicated by this discussion, there are many factors which influence these interactions (e.g., thedose of each metal, the nutritional status of the person exposed, etc.) and at this time it is notpossible to precisely predict how cadmium, lead, and zinc may interact when people are exposedsimultaneously to all three metals.
d. Sulfuric Acid
As described in the Pathways Analyses section, there was a major malfunction of the NZCsulfuric acid recovery plant in July 1977, resulting in the release of excessive amounts of sulfurdioxide (16). Residents around the NZC facility reported that the release caused health effects. Those effects and the chance of long-term consequences from the exposures are discussed.
Once in the air, sulfur dioxide can be converted to sulfuric acid, especially in the presence ofcertain metals (30). This is important because sulfuric acid is much more toxic (i.e., causesharm at much lower concentrations) than sulfur dioxide. The two chemicals are identical in thehealth effects caused, which are the irritation and eventual burning of the eyes, nose, throat,lungs, and skin at the time of exposure. In addition, the teeth can be etched. While those effectscan be permanent, they are not delayed in their onset. Thus, any health consequences of theexposure in July 1977 would have occurred at that time, and not later.
In this section, health outcome data of two types are reviewed and evaluated: cancer mortalitydata for Washington County, and lead and cadmium data for Bartlesville residents. In addition,the guidelines that ATSDR follows for evaluating information from health outcome databasesare reviewed.
In a public health assessment, available health outcome databases are identified for the area nearthe site. From those data, ATSDR selects health outcomes for further evaluation based onbiological plausibility or community health concerns (22).
For biological plausibility, the decision to evaluate health outcome data depends on whether a completed exposure pathway exists for a chemical suspected of causing the health outcome ofconcern (22). The selection of a noncarcinogenic health outcome is based on a review of thetoxicologic literature for that contaminant of concern.
When a contaminant of concern has been identified as a carcinogen, health outcomes for themajor anatomical sites are usually selected for evaluation (22). Designating a chemical as acarcinogen for purposes of health outcome data evaluation is based on the following criteria:
- Classification by the National Toxicology Program (NTP)(1) in itsAnnual Report on Carcinogens as a "known human carcinogen" or"reasonably anticipated to be a carcinogen"; or
- Classification by the International Agency for Research on Cancer (IARC)(2) as a1, 2A, or 2B carcinogen; or
- Classification by EPA(3)as an A, B1, or B2 carcinogen.
- Classification by the United States Occupational Safety and Health Agency(OSHA)(4)
A latency period of at least 10 years between exposure and diagnosis has been observed in moststudies of human cancer (22). If exposure began less than 10 years prior to the latest dataavailable, analysis of health outcome data for cancer incidence or mortality is not likely to be useful, particularly if the exposure level is low.
Even when health outcomes do not meet ATSDR's guidelines for biological plausibility,evaluation of health outcome data can provide a basis for addressing community healthconcerns.
Cancer is considered a biologically plausible health outcome because cadmium and lead areconsidered probable human carcinogens and because both contaminants are in completed air andsoil human exposure pathways (24,25). Significant exposure to lead and cadmium in air and soiloccurred for about 70 years.
Developmental or birth defects were considered biologically plausible health outcomes. Lead is strongly associated to those effects and is in the air and soil completed exposure pathways (25).
Neither cancer incidence nor birth defects data could be evaluated in this public healthassessment because The Oklahoma State Tumor and Birth Defect Registries have no accessibledata for Washington County for either cancer or birth defects. Cancer incidence data have beencollected for Washington County by the local hospital for several years; however, those data arecurrently not compatible with the state's system. The Oklahoma State Department of Health(OSDH) is in the process of making the Washington County data compatible. The OklahomaBirth Defects Registry is scheduled to incorporate Washington County data into the state systemin 1994/1995.
2. Cancer Mortality Data
To identify cancer mortality rates, ATSDR reviewed mortality data on 30 anatomical sites forWashington County. The database used for the review is maintained by the Office of Analysisand Epidemiology of the National Center for Health Statistics, Centers for Disease Control andPrevention (CDC).
Information specific to the City of Bartlesville area is not available. Mortality data forWashington County were accessed for 1979 to 1988, the only years available. The age-adjustedrates for Washington County were compared to the rate for Oklahoma. Because the Bartlesvillearea is about 91% white, the comparisons listed below will be for whites. The comparison ofrates for African-Americans and others produced results similar to those described in thefollowing paragraphs.
Of the 30 anatomical sites evaluated, the number of deaths for multiple myeloma and ovariancancer in Washington County was greater than what would be expected from the numbers forthe State of Oklahoma. There were 25 deaths from multiple myeloma in Washington County for1979 to 1988, while 15 would have been predicted based on the 1,031 deaths for the State ofOklahoma. There were 34 deaths from ovarian cancer, while 22 would have been expectedbased on the 1,498 deaths for the state.
The available data on cadmium and lead do not identify ovarian cancer or multiple myeloma aspossible health outcomes (24,25). Human studies do not identify any cancers associated withexposure to lead. Occupational studies indicate that cadmium may be a weak lung carcinogen. Animal studies indicate that cadmium can cause lung cancer and that lead can cause kidneycancer. For Washington County, the occurrence of lung and kidney cancer was as expectedfrom the state rates.
a. Ovarian Cancer
The rates of ovarian cancer are greatest in highly industrialized countries and in women 40 to 70years old (38). There is an indication of some kind of environmental or dietary influence on theoccurrence of this cancer, based on studies of Japanese women. The rate of ovarian cancer inJapan is one of the lowest in the world. However, the rate in Japanese who move to the UnitedStates as children is close to that for white Americans. However, the only proven associationwith an environmental agent is the association with asbestos. No association was demonstratedfor viruses, radiation, or other substances. There is also an association of ovarian cancer withdisordered endocrine function. Occurrence is greater in women who had few or no pregnanciesor were infertile.
b. Multiple Myeloma
Multiple myeloma is a cancer in which there is an over production of defective B-cells (39). B-cells are a type of white blood cells. Multiple myeloma makes up about 1% of all cancers inwhites and 2% in African-Americans. The average age of onset is about 70 years. Factors suchas family history of multiple myeloma and exposure to petroleum products, asbestos, andradiation have been associated with the occurrence of multiple myeloma. This cancer has notbeen associated with cadmium and lead.
Evaluations of cancer mortality data have limitations. The cancer mortality data used do notinclude information on personal risk factors (smoking, diet, alcohol, etc.) or on occupational andenvironmental exposures to chemicals. Analyses of those data can only be descriptive andcannot be used to determine associations with possible agents. There is an inherent 5% chancethat any excess in observed cancer cases is due to random variation alone.
Another limitation is whether mortality data reflect the actual frequency of a health outcome(i.e., deaths plus those who survive) (40). Factors such as quality of health care, high survivalrates, and misclassification of cause of death can lead to differences in mortality rates eventhough the true frequency of the health outcome has not changed.
3. Studies of Contaminants in Body Tissues
Testing blood, tissue, or other body fluids from individuals living around a site for possible sitecontaminants can identify whether exposure has occurred and whether contaminantconcentrations are high enough to cause adverse health effects. The linking of elevated levels of a contaminant to a site requires the evaluation of other possible exposure sources.
The body tissue data for Bartlesville residents indicates that exposure to site-related cadmiumand lead has occurred in the past. Only blood lead studies have been conducted recently (1991through 1993). These studies indicate that people are presently being exposed to lead. Thisconclusion is based on the identification of elevated blood lead and cadmium concentrations,elimination of other possible exposures, and an association between soil cadmium and leadlevels and blood cadmium and lead levels.
a. Review of Blood Contaminant Data
There are four major sets of data on blood cadmium and lead for the Bartlesville area during the1970s (2,3,9). In 1975, CDC conducted a study of 19 cities with lead, copper, or zinc smeltersand found that 78 of 87 Bartlesville children (89.6%) had blood lead levels above 10micrograms of lead per deciliter of blood (µg/dL), 33 of 87 (37.9%) had levels above 30 µg/dL,and 3 of 87 (3.4%) had levels above 80 µg/dL (2). Those children were 1 to 5 years old, andeach lived within 4 miles of the NZC smelter. The mean blood lead level for the 86 childrenwas 28.6 µg/dL. The mean blood cadmium level was 0.5 µg/dL, and 15 of 87 children hadlevels of 1.0 µg/dL or greater. The mean blood lead and blood cadmium levels for theBartlesville children were the highest of the mean levels for the 19 smelter towns investigated.
In 1977, the Research Triangle Institute conducted a comprehensive exposure assessment ofBartlesville residents which included testing of blood, hair, soil, house dust, interior paint, andtap water (3). For children 1 to 5 years old living near the smelter, 54 of 67 (80.6%) had bloodlead levels of 10 µg/dL or greater, 25 of 67 (37.3%) had levels of 30 µg/dL or greater, and 1 of67 (1.5%) had a level of 80 µg/dL or greater. Twenty-seven of the 67 children (40.3%) testedhad blood cadmium levels above 0.2 µg/dL, and 4 of those had levels 1.0 µg/dL or greater. TheResearch Triangle Institute study also included tests of 341 individuals older than 5 years, andresults indicated similar blood lead and cadmium levels to those of the younger children.
Blood lead studies were conducted by Environmental Consultants Laboratory from September1977 to December 1979 as a part of a class action law suite 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; 53.9 percent of the samplesexceeded the 1976-1980 National Health and Nutrition Examination Survey (NHANES) meanblood lead for all ages of 13.9 µg/dL.
In 1991 to 1993, the OSDH(5), with assistance of ATSDR and the Washington CountyDepartment of Health, sampled the blood of Bartlesville residents for lead (31). Of the childrenunder 6 years old, 36 of the 246 living in the contaminated area of Bartlesville (14.6%) hadblood lead levels of 10 µg/dL or greater. The highest level was 24.0 µg/dL. In contrast, none ofthe 127 children under 6 who resided in the non-contaminated area of Bartlesville had levels of10 µg/dL or greater.
b. Evaluation of Blood Contamination
These four sets of data support an association between contaminant levels in blood and living inthe area near the smelter. The two sets of data from the 1970s were obtained when there werelittle or no restrictions on smelter emissions (4). The much higher blood lead levels (80% at 10µg/dL or greater) identified in the 1970s studies indicate that the smelter emissions had a stronginfluence on blood levels. This conclusion is further supported by the sampling of house dust,residential soil, and blood in the Research Triangle Institute study, which identified higher levelsof cadmium and lead in all three media in the area downwind from the smelter than in areasupwind from the smelter (4). This area is north of the smelter. Parental occupation and leadlevel in interior paint were not related with blood lead levels. Incidentally, the percentage of homes in Bartlesville with lead in interior paint was similar to percentages in two nearbycommunities where blood lead levels were much lower.
The results of the 1990s testing, while lower than those from the 1970s, indicate that childrenliving around the smelter have higher blood lead levels than children living elsewhere inBartlesville (31). Those elevated levels appear to be due, at least partially, to the elevatedresidential soil lead levels. This determination is based on the follow-up of children with 10µg/dL or greater blood lead and an association between blood lead levels and soil lead levels.(6)
Additional evidence for an association between children's blood lead levels and lead soilcontamination comes from three literature reviews evaluated (32-34). All 3 concluded that soillead levels of 1,000 mg/kg would increase concentrations in blood by 0.6 to 65 µg/dL, with anaverage increase of 4-5 µg/dL. This wide range was due to different sources of lead, exposureconditions, and exposed populations. The smallest increases in blood lead were observed incommunities with mines or inactive smelters. The health effects associated with such anincrease would depend partly on the existing body burden of lead.
c. Toxicology of Lead and Possible Health Consequences from Exposure
Exposure to lead causes a wide range of effects (25). The level of lead in blood is a goodmeasure of recent exposure, and it also correlates well with health effects. Children areespecially sensitive to lead, and many of its effects are observed at lower concentrations inchildren than in adults. Levels of 10 µg/dL and perhaps lower in children's blood have beenassociated with decreased IQ and impaired hearing and growth. Neurological effects may persistafter exposure has ceased and blood lead levels have returned to normal (35). Lead cansignificantly affect both the reproductive process and the development of the fetus at blood leadlevels in a pregnant woman as low as 10 µg/dL. Documented effects include reduced productionof sperm, premature birth, and low birth weight. In adults, levels as low as 15 µg/dL are linkedto increases in blood pressure and erythrocyte protoporphyrin.
The increased vulnerability of children results from a combination of factors, including thefollowing:
|(1)||The increased susceptibility of the developing nervous system to theneurotoxic effects of lead, |
|(2)||A higher average rate of soil ingestion among children than among adults,|
|(3)||The greater efficiency of lead absorption in the gastrointestinal tract ofchildren,|
|(4)||Children's greater prevalence of iron or calcium deficiencies, which mayexacerbate the toxic effects of lead, and|
|(5)||The ready transfer of lead across the placenta to the developing fetus (36).|
For the OSDH/ODEQ study's 36 children with blood lead levels of 10 µg/dL and greater, effectssuch as slightly decreased IQ, impaired hearing and growth, and decreased Vitamin Dmetabolism were possible. Whether any of those effects occurred was dependent on thenutritional status and total body burden of lead for each child (25,37). Increased blood leadlevels created the possibility of such health effects as decreased hemoglobin synthesis, colic,anemia, kidney damage, and encephalopathy for many of the children in the 1970s Bartlesvillestudies (25,37).
d. Possible Health Consequences from Exposure to Cadmium
Health effects were possible for those children in the two 1970s studies with blood cadmiumlevels of 1.0 µg/dL and perhaps lower (24). Kidney dysfunction was identified among workerswith blood cadmium levels of 1.0 µg/dL who had been exposed to cadmium for 20 years. Littleis known about cadmium exposure's health consequences for children. There is a discussion ofthe toxicology of cadmium in the Toxicological Evaluation section of this public healthassessment.
The community health concerns identified earlier are addressed as follows:
- Is the cancer incidence (as the result of occupational and environmental exposures)in the Bartlesville area elevated?
There was not appropriate cancer incidence data available for the Bartlesville area to allow an answer to this question. However, ATSDR did evaluate cancer mortality data for WashingtonCounty. As described in the Health Outcome Data Evaluation section, deaths from multiplemyeloma and ovarian cancer were greater than would have been expected from state rates. There is no evidence that cadmium or lead can cause those two cancers.
- Is the incidence of birth defects in the area elevated? If so, could the increasedincidence be caused by the same causes producing birth defects in horses born nearthe smelter before the smelter used pollution control devices ("smelter colts")?
This question could not be addressed because of a lack of information. Appropriate birth defectdata for the Bartlesville area were not available. Birth record databases identify only those birthdefects that can be recognized at birth (40). The developmental effects associated with leadexposure are not diagnosed until well after birth (25). Therefore, birth record data were notobtained.
- Is the environmental contamination related to behavioral problems of children inthe area?
Lead exposure can cause behavioral problems in young children (25,37). To determine whethera specific child's behavioral problems are linked with lead, it would be necessary to test the childfor exposure to lead and, if an elevated level were found, to investigate possible exposuresources, including soil, paint, etc. Through this process, an association between theenvironmental contamination and a child's behavioral problems could be established.
- Is Multiple Sclerosis (MS) caused by lead and/or cadmium?
There is no indication that MS is caused by lead or cadmium (41). MS is a disease which causesthe myelin coating around the nerves to disappear over time. This process usually results in agradual loss of neural function. The average age of onset of MS is about 30 years. Viral agentsare suspected as the causative agent for MS, but there is no strong evidence supporting a linkwith any specific virus. There is no good evidence for an association with any chemical or with radiation.