Environ Geochem Health (2009) 31:47–59 DOI 10.1007/s10653-008-9154-0
O RI G I N A L P A P E R
Potential health impacts of heavy-metal exposure at the Tar Creek Superfund site, Ottawa County, Oklahoma John S. Neuberger · Stephen C. Hu · K. David Drake · Rebecca Jim
Received: 6 March 2007 / Accepted: 17 January 2008 / Published online: 28 February 2008 © Springer Science+Business Media B.V. 2008
Abstract The potential impact of exposure to heavy metals and health problems was evaluated at the Tar Creek Superfund site, Ottawa County, Oklahoma, USA. Observed versus expected mortality was calculated for selected conditions in the County and exposed cities. Excess mortality was found for stroke and heart disease when comparing the exposed County to the state but not when comparing the exposed cities to the nonexposed rest of the County. However, sample sizes in the exposed area were small, population emigration has been ongoing, and geographic coding of mortality data was incomplete.
J. S. Neuberger (&) Department of Preventive Medicine and Public Health, University of Kansas School of Medicine, Mail Stop 1008, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA e-mail:
[email protected] S. C. Hu Scripps Clinic, Green Hospital, 10666 North Torrey Pines Road, GEN2, La Jolla, CA 92037-1093, USA e-mail:
[email protected] K. D. Drake US Environmental Protection Agency, Region VII, 901 North 5th Street, Kansas City, KS 66101, USA e-mail:
[email protected] R. Jim L.E.A.D. Agency, 19257 South 4403 Drive, Vinita, OK 74301, USA e-mail:
[email protected]
In an exposed community, 62.5% of children under the age of 6 years had blood lead levels exceeding 10 g/dl. The relationships between heavy-metal exposure and children’s health and chronic disease in adults are suggestive that a more thorough investigation might be warranted. A number of possible environmental and health studies are suggested, including those focusing on possible central nervous system impacts. Unfortunately, the exposed population is dispersing. One lesson learned at this site is that health studies need to be conducted as soon as possible after an environmental problem is identiWed to both study the impact of the most acute exposures and to maximize study sample size—including those exposed to higher doses—and minimize the loss of individuals to follow-up. Keywords Hazardous wastes · Health studies · Lead · Mining wastes · Superfund site Abbreviations ATSDR Agency for Toxic Substances and Disease Registry BRFSS Behavioral Risk Factor Surveillance Survey CDC Centers for Disease Control and Prevention dL Deciliter EPA US Environmental Protection Agency ICD International Statistical ClassiWcation of Diseases mg/kg Milligrams per kilogram OR Odds ratio
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SEM/ EDS USGS g/L m WHO
Environ Geochem Health (2009) 31:47–59
Scanning electron microscope/energy dispersive spectroscopy US Geological Survey Micrograms per liter Micron or micrometer World Health Organization
Introduction We present a case study of a prominent Superfund site in the United States. This overview provides background information on community exposures and health indicators, illustrates the diYculties of evaluating this site’s public health impact, suggests potential health problems, indicates the lack of previous in-depth health research at the site, and suggests areas for future environmental and health research. A Superfund site is an abandoned hazardous waste site in the United States subject to the Comprehensive Environmental Response, Compensation and Liability
Act (CERCLA) of 1980. The CERCLA law allows federal funding to be spent on investigating and remediating the environmental contamination at these designated sites. Additionally, the law has many other provisions that apply to these sites, such as requirements for a public process (i.e., a public meeting and a formal comment period) and the ability of the federal government (the US Environmental Protection Agency) to seek funds from private and public companies that are deemed liable for the contamination. The Tar Creek Superfund site (site) area is part of the Tri-State Mining District of Kansas, Missouri, and Oklahoma, USA (Drake 1999) (Figs. 1, 2). Besides Ottawa County, Oklahoma, the district includes Cherokee County, Kansas; Jasper County, Missouri; and Newton County, Missouri (Fig. 2). Beginning in the latter half of the nineteenth century, until the early 1970s, when the last of the mines were closed, the area was a major supplier of zinc and lead (ATSDR 1996; Missouri Department of Health 1995; Reed and Czarnecki 2006). The district produced 50% of the
Fig. 1 The Tar Creek Superfund site (US Environmental Protection Agency)
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Fig. 2 Overall impacted area in three states and four counties (http://www. fws.gov/mountain-prairie/ NRDA/CherCO_KS/CherokeeCounty.htm, accessed 3/5/07)
US production of zinc and 10% of the production of lead during the 100-year period 1850–1950. The district was also an important source of cadmium and germanium (US Department of Interior 1983). Portions of the district were declared a Superfund site in the mid 1980s for two reasons: (1) the presence of high concentrations of lead, zinc, and cadmium in the mine wastes and tailings, and (2) the presence of acid mine water (with high concentrations of heavy metals) emerging from surface and groundwater into the surrounding creeks, particularly in Oklahoma. Lead concentrations of up to 13,000 mg/kg were found in mine tailings (or Xoatation ponds) and 1,600 mg/kg (max) in mine waste (chat) in Cherokee County, Kansas, just north of the Tar Creek site (ATSDR 1997a, US Environmental Protection Agency 2004). After site evaluation and measurements, US EPA decided on site boundaries. Background soil levels of less than 240 mg/kg of lead and 25 mg/kg of cadmium were not considered to be mining-inXuenced. The Tri-State district is the largest heavy-metalmining Superfund site location in the United States in terms of the total area degraded, the volume of chat left behind, and the size of the population exposed. There are four Superfund sites within the Tri-State district. Areas in Cherokee County, Kansas, and
Newton and Jasper Counties, Missouri, have been remediated by the EPA (ATSDR 1993; US Environmental Protection Agency 1996, 1997b). Whereas all four contiguous counties in the three states have similar environmental degradation issues, the Tar Creek portion in Ottawa County, Oklahoma, has been more environmentally degraded than the other three. Environmental damage is extensive, with sinkholes, Xoatation ponds, and mine tailings present. Tar Creek is potentially an extremely hazardous area because of its size (40 square miles), the number of people exposed, the presence of extensive mine-tailing accumulations (some piles are as high as 250–300 feet), the concentration of heavy metals (especially lead, cadmium, and zinc), and the exposed population of children (ATSDR 1993; US Environmental Protection Agency 1997b). Approximately 10% of the county’s area and 18% of the county’s population lives in Wve cities included within the site boundaries, with 45% of the county’s population (15,000) living either on site or in close proximity. Public water supply wells have been contaminated by mine water, including lead and cadmium (US Geological Survey 1995). The town of Picher’s water supply contained elevated levels of metals in 1985 and an alternative water supply was established (ATSDR 1993).
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Lead exposure has been linked to kidney, neurologic, and vascular toxicity and mortality from hypertension and stroke. Cadmium exposure has been linked to kidney disease, chronic obstructive pulmonary disease, and hypertension, including mortality from stroke. (ATSDR 1999a, 1999b; Sullivan and Krieger 2001; Klaassen et al. 1996). An increased risk for tuberculosis, silicosis, and lung cancer has been related to occupation in the lead–zinc mines (Burke et al. 1979; Neuberger and Hollowell 1982a, 1982b; Snider et al. 1982). Lung cancer among miners was related to cigarette smoking, exposure to mining dusts, and radon (Neuberger et al. 1983). Mortality analysis in Cherokee County during the 1980–1985 period revealed that there were a statistically signiWcant excess of deaths for both genders combined from heart disease, stroke, pneumoconioses, kidney disease, and accidents. Mortality rates in Galena City were signiWcantly elevated for hypertensive disease (women aged 65 and older), ischemic heart disease (men and women aged 65 and older), and cerebrovascular disease (women aged 45–64) (Neuberger et al. 1990). A prevalence survey of residents of the Galena contaminated area and two control towns revealed that among women aged 65 years of age and older who had resided for 5 or more years in that area, there was a statistically signiWcant increase in the reported prevalence of chronic kidney disease, heart disease, and anemia. Statistically signiWcant relationships existed for the total population between residency factors and stroke, chronic kidney disease, hypertension, heart disease, skin cancer, and anemia. Residency factors included proximity to the smelter, exposure to mine tailings, private well-water use, and length of residence in the area (Neuberger et al. 1990). Given the above information, we thought it important to investigate whether residence at or near this Superfund site in Ottawa County, Oklahoma, was related to excess mortality, low birth weight, or blood lead levels in children.
Materials and methods Mortality data were obtained from the Oklahoma State Department of Health and were analyzed to determine whether there were signiWcant diVerences when comparing the county to the state and the exposed cities to
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the unexposed area of the county outside the site. Observed mortality was compared with expected mortality for conditions selected either because of their associations with heavy metals or because they were elevated in previous studies either in Cherokee County or Galena, Kansas, (Neuberger and Hollowell 1982a, 1982b; Neuberger et al. 1983; Neuberger et al. 1990). The conditions chosen were lung cancer, tuberculosis, bronchitis, emphysema, and asthma combined; kidney disease, hypertension, stroke, and heart disease. The observed number of children with low birth weight or who died in infancy (conditions associated with elevated blood lead levels) were also compared to that expected based on rates from the state. Geographic comparisons were made both between the site, the county (exposed areas of Ottawa County versus unexposed areas) and the state. The exposed area of the county has been deWned to include Wve cities/towns located within the boundaries of the Superfund site (Fig. 1). Their populations in 2000 were: Cardin 150, Commerce 2,645, North Miami 433, Picher 1,640, and Quapaw 984. The populations of the four unexposed cities/towns (three of which are far oV-site and thus oV the map) in 2000 were: Afton 1,118, Fairland 1,025, Miami 13,704, and Wyandotte 363. The total population of Ottawa County in 2000 was 33,194; that of the state of Oklahoma was 3,450,654. Death- and birth-certiWcate information was obtained for the period 1999–2001 from the Oklahoma State Department of Health. Population data were obtained for Ottawa County, the state, and Wve cities from the year 2000 US Census. Low birth weight was reported for infants weighing 500 mg/kg, the highest was 10,800 mg/kg. In 2,055 homes sampled in the mid-1990s, 65% had soil lead concentrations greater than 500 mg/kg (US Environmental Protection Agency 1997b). Four schools, three day care centers, and 11 ball Welds and/or parks also had elevated levels of soil lead (ATSDR 1995a, b). In addition, 7/28 areas Table 5 Behavioral riskfactor survey comparing Ottawa County to the state of Oklahoma 2001–2002
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Reported health or exposure problem
measured for soil cadmium were elevated >100 mg/kg, with the highest at 448 mg/kg (US Environmental Protection Agency 1997b). Two schools, one day care center, and four ball Welds and/or parks had elevated levels of soil cadmium (ATSDR 1995a, b). In the mid-1990s, the prevalence of elevated blood lead levels (¸10 g/dl in children aged 6–72 months) was 62.5% in one of the mining towns, with an overall prevalence of 30.5%. In a 1992–1993 survey of 189 Native American children from the Tar Creek area, 35% had elevated blood lead levels (exceeding 10 g/dl) (ATSDR 1997a; US Environmental Protection Agency 1997b). In a July and August 1995 survey of blood lead levels in 230 children in the Wve mining communities of Picher, Cardin, Commerce, Quapaw, and North Miami, 28.3% had elevated blood lead levels (¸10 g/dl), with some exceptionally high (¸30 g/dl). These Wndings compare with a state rate of elevated blood lead levels of 2.4% (ATSDR 1997a). During 1991–1994, the CDC estimated that 4.4% of children aged 1–5 years had blood lead levels in excess of 9 g/dl (Kegler et al. 2000). In an autumn 1996 survey of Picher, Cardin, and Quapaw, 38.3%, 62.5%, and 13.4%, respectively, of children exceeded the blood lead level of 10 g/dl (US Environmental Protection Agency 1997b). Thus, these levels were elevated in the mining towns, varied among the exposed communities (with Picher and Cardin the highest), and decreased over time.
County % yes (n)
95% ConWdence interval
State % yes (n)
95% ConWdence interval
Asthma
18.6 (18)
6.9–30.3
10.7 (1,245)
10.0–11.4
Hypertension
30.6 (20)
18.4–42.8
28.6 (1,438)
26.9–30.2
Arthritis
30.7 (21)
18.7–42.6
27.0 (1,395)
25.4–28.6
Joint pain or swelling
48.5 (41)
35.0–62.0
46.5 (3,405)
45.1–48.0
Smoked 100 or more cigarettes
60.1 (74)
49.6–70.5
49.4 (5,547)
48.2–50.6
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In the summer and autumn of 1997, venous blood samples were obtained from a representative sample of 224 children aged 1–6 years in northeastern Ottawa County, Oklahoma (Malcoe et al. 2002). The mean blood lead level was 5.8 g/dl, and increased risks for blood lead levels >10 g/dl were independently associated with the increase in mean Xoor-dust lead and yard-soil lead. Interior and exterior lead-based paints were weakly correlated with blood lead levels, whereas lead in drinking water was not correlated with blood lead levels. In another report, the adjusted odds ratio for blood lead levels >10 g/dl was 3.4 (95% CI = 1.3–8.8) for children living in the exposed (Superfund) towns. In addition, nearly 20% of the homes that were nearby but outside the mining area had contaminated soil, thus supporting the idea that these heavy-metal contaminants were being transported regionally, most likely via the atmosphere (i.e., wind) (Lynch et al. 2000). In the summer and autumn of 2000 a crosssectional study was conducted after a 2-year remediation eVort. Venous blood lead levels of children aged 1–6 years in 2000 (n = 387) showed a statistically signiWcant decrease in blood lead levels in both the exposed and nonexposed communities (Kegler and Malcoe 2004). Blood lead level data for 1996–2000 for children under the age of 6 years were summarized by the Oklahoma Childhood Lead Poisoning Prevention
Program (Table 6). A total of 79,748 tests were performed on 50,927 children. Five mining and four nonmining cities within Ottawa County were included. Both the highest and the most recent blood lead levels were utilized. The percentages of children with elevated (¸10 g/dl) blood lead levels for the highest blood lead test (n = 2,058 children tested in the county) were 29.03% in Cardin and 22.65% in Picher. Corresponding Wgures for the most recent blood lead test (n = 2,055 children tested in the county) were 18.18% for Cardin and 16.81% for Picher. Comparable Wgures for the county were 7.14 % and 5.35%, respectively. The highest values in both sets of readings were in the exposed towns of Picher and Cardin. Comparing the highest blood lead test to the most recent blood lead test, all values in the Wve mining cities declined with the exception of North Miami (Braggio 2002). This is most likely due to the combination of remediation eVorts and community education.
Discussion Whereas there is evidence of excessive mortality among adults at the county level of detail, this excess disappears when comparing the exposed cities to the rest of the county. These Wndings are similar to the results for Cherokee County, Kansas, but are in
Table 6 Percent and number of children younger than 6 years of age with venous conWrmed elevated blood lead levels in 1996–2000. Five cities, Ottawa County, and state of Oklahoma Cities/places
Highest blood lead test
Most recent blood lead test
% Not elevated (n)
% Elevateda (n)
% Not elevated (n)
% Elevateda (n)
Cardin
71.0 (22)
29.0 (9)
81.8 (27)
18.2 (6)
Commerce
96.3 (257)
3.8 (10)
96.9 (252)
3.1 (8)
North Miami
90.0 (36)
10.0 (4)
89.7 (35)
10.3 (4)
Picher
77.4 (181)
22.7 (53)
83.2 (198)
16.8 (40)
Quapaw
90.5 (200)
9.5 (21)
92.6 (200)
7.4 (16)
Five exposed cities
87.8 (696)
12.2 (97)
90.6 (712)
9.4 (74)
Rest of Ottawa County citiesb
96.1 (1,215)
4.0 (50)
97.2 (1,233)
2.8 (36)
Total Ottawa County
92.9 (1,911)
7.1 (147)
94.7 (1,945)
5.4 (110)
State of Oklahoma
98.0 [97.6–98.4]c (49,908)
2.0 [1.6–2.4]c (1,019)
98.5 [98.2–98.8]c (50,158)
1.5 [1.2–1.8]c (769)
Equal to or exceeding 10 g/dl Afton, Fairland, Miami, and Wyandotte c 95% ConWdence interval (Braggio 2002) a
b
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Environ Geochem Health (2009) 31:47–59
contrast to the results found in Galena, Kansas. The results found at this site could possibly be related to: (1) population emigration, and/or (2) the absence of speciWc geographic coding for mortality at the city or zip code level of detail. The population of Picher is declining and now is only a fraction of what it was when the mining operations were ongoing. Individuals originally exposed on-site now, some 25 years later, have likely moved oV-site and now reside outside of the exposed cities. In 2004, there was an acceleration of this process by a buyout of 51 households in Picher with children under the age of 6 years by the state of Oklahoma. There are other plans to oVer a buyout to additional residents of the impacted area. Exposures to mine wastes are not totally conWned to the Wve exposed cities. Airborne and waterborne contaminant pathways exist that can spread out some of this material regionally, including to some of the unexposed cities/towns and areas of Ottawa County. Examples of other activities that can spread the tailings include removal of chat for use in gravel roads, wall plasters, and mortar construction throughout the Tri-State Mining District (Neuberger et al. 1990; Perry et al. 2005). An eVort is now underway to characterize sediments in local streams and rivers potentially impacted by mining activities. Locally grown food supplies (e.g., tomatoes) or Wsh may also be contaminated with metals (e.g., cadmium). Some yard soils in unexposed areas may also be contaminated with heavy metals from nonmining waste sources (e.g., lead paint). Whereas the entire universe of unexposed areas was not sampled, the area of greatest concern was investigated, and the majority of pollution from mining waste was determined to be in the exposed areas (US Environmental Protection Agency 1997a). Whereas mortality data are frequently used for population surveillance and are readily available, such data can be insensitive to the underlying incidence of disease. The overall small sample size aVects the statistical power of the analysis. With the exception of heart disease, stratiWcation by gender may not be that meaningful because of that problem. A larger sample size (e.g., a 5-year mortality data set) would have signiWcantly helped, particularly at the city level of detail. To determine what health problems might have been elevated in an earlier time, mortality data from the Oklahoma State Department of Health from 1988
55
through 1998 were accessed (www.health.ok.gov/ ok2share) recently (2 Oct 2007). For children, the results indicated a reduced rate of both infant mortality and low birth weight in Ottawa County compared with the state, with comparisons similar to what were observed in this analysis. For adults, results indicated that for Ottawa County residents, mortality rates were increased 56.5% for lung cancer; 100% for tuberculosis; 40.0% for bronchitis, emphysema, and asthma; 69.2% for kidney disease; 100.0% for hypertension; 42.0% for stroke; and 31.8% for heart disease when compared with the state. The online system does not provide either age-adjusted data for the adult analyses or statistical signiWcance. Thus, its results cannot be considered deWnitive. However, it does suggest a potential problem. Another investigation that included mortality outcomes from 1999 to 2003 found elevated ageadjusted total mortality rates for each year in Ottawa County compared with both the state and the United States. Over the total time, age-adjusted mortality rates were elevated for ischemic heart diseases and some other conditions, although the authors indicated that this result was most likely due to chance (ATSDR 2006). An investigation of persistent mortality clusters in US counties found that Ottawa County had a statistically signiWcantly elevated age-adjusted total mortality rate in at least four of seven 5-year periods from 1968 through 2002. These data were not gender or race speciWc (Cossman et al. 2007). In all the various supplementary examples cited, mortality data from earlier years that focus on the most crucial historic data—comparing exposed to nonexposed cities—do not exist. The lower socioeconomic status of the exposed communities could also be a limitation, potentially leading to higher than expected mortality. Communities within the county and site were compared socioeconomically using the median family income for 1999 obtained from the Year 2000 US Census (exposed communities: $25,417–$30,547; county: $32,368; state: $40,709). However, no signiWcant excess of infant or selected adult mortalities were found in these exposed lower socioeconomic status communities. The relationship between mortality and environmental exposures at this site can only be considered associations or correlations at the group or community level of detail. Studies on individuals are needed
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to establish more reWned associations or correlations; those at the individual level of detail. Using health outcome and exposure results from individuals, one can assess causality using such factors as consistency with other studies (human and animal), biological plausibility, and the presence of a dose–response relationship. Possible confounders, such as smoking, can best be addressed at the individual level of detail. Whereas the BRFSS survey indicates that there has been no overall excess of smoking among residents of Ottawa County, there has been an excess among men. This could be a contributing factor to their observed excess in heart disease and stroke mortality. However, data are not available that evaluate the relationship between health outcomes and smoking either in Ottawa County or within the subset exposed population. Sample sizes in the survey were very small, and the survey was not designed to focus on the comparison between exposed and nonexposed areas. The survey did not attempt to identify any particular environmental exposure problem. Because of the high poverty rate in Ottawa County (about 20%) (Health Care Information Division 2001) and the fact that the BRFSS survey was via the telephone, a number of residents may not have been surveyed. A 2005 BRFSS survey indicated a higher prevalence of asthma and some other conditions in Ottawa County compared with the state, although the authors indicated that this result was most likely due to chance. This Wnding for asthma is similar to the results obtained in this study. This 2005 survey was not designed to focus on the comparison between exposed and nonexposed areas. It is unclear what the survey sample size was in either Ottawa County or the state (ATSDR 2006). More subtle eVects of lead contained in mining wastes should not be ignored, particularly among children. Whereas a variety of heavy metals (and silica) are present to varying degrees, lead appears to be the greatest environmental exposure of concern to human health, particular for children. Pathways of lead exposure are primarily from soil and from windborne dust, with hand to mouth behavior common among younger children. Whereas mortality data for infants or the total population did not clearly indicate a statistically signiWcant underlying problem, some of the children aged 6–72 months did have elevated blood lead levels in the range of 10–20 g/dl. This exposure could have
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resulted in lower intelligence quotient (IQ) scores, decreased attention span, decreased bilateral coordination, hearing deWcit, decreased speech and language processing, decreased hemoglobin formation, decreased Wne-motor skills, and decreased school performance (ATSDR 1997b; Klaassen 1996). Even for blood lead levels
