PUBLIC HEALTH ASSESSMENT
KERR-MCGEE REFINERY SITE
CUSHING, PAYNE COUNTY, OKLAHOMA
A. On-Site and Off-Site Contamination
ATSDR reviewed investigation data and made an initial selection of contaminants that may warrant further evaluation for public health significance. The extensive investigation programs, initial selection process, and tables of the contaminants chosen for further evaluation are presented in Appendix C (begins on Page 36)
The contaminants identified by that process and the exposure pathways in which they occur then were evaluated to determine whether any may be of public health significance. Those health significance evaluations identified several contaminants of possible public health concern (Key Contaminants) in certain environmental media both on site and off site. Those Key Contaminants are identified in the next paragraph.
Key contaminants that were determined to warrant health clarification discussion in the Public Health Implications section (Page 14) include:
C. Quality Assurance and Quality Control
ATSDR has relied on laboratory data provided in the referenced documents. Not all such data included quality control information. The completeness and reliability of laboratory information could affect the validity of ATSDR's conclusions.
ATSDR believes that the disposal pits, radiation management areas, building remnants, and debris do not pose physical or other personal hazards to knowledgeable workers. The potential hazard to intruders is mitigated by the substantial fences surrounding pits and radiation management areas, the fence system (at least 3 wire strands) and postings surrounding the entire property, and the general remoteness of the property.
ATSDR identifies human exposure pathways by examining environmental and human components that might lead to contact with contaminants. A pathway analysis considers five elements: a source of contamination, the presence or transport of contaminants in an environmental medium, a point where human exposure could occur, a route of human exposure, and an exposed population. Completed exposure pathways are those for which the five elements are evident, indicating that exposure to a contaminant has occurred in the past, is currently occurring, or will occur in the future. ATSDR regards people who come in contact with contamination as exposed: for example, people who drink contaminated water, or who reside in an area with contaminated air, or who work or play in contaminated soil are considered exposed Potential exposure pathways are those for which one or more of the elements is not clearly defined but through which exposure is plausible. Potential pathways indicate that exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future.
A. Completed and Potential Exposure Pathways Identified
ATSDR staff (through review of site history; past, current, and future activities; and media sampling data) have identified numerous completed past, current, or future exposure pathways on the site, off the site on Property A, and elsewhere off site. Those completed pathway components are summarized in Appendix D in three separate tables: 1) On-Site Pathways; Table D1 (see Page 115), 2) Off Site Pathways other than Property A; Table D2 (see Page 116), and 3) Property A Pathways; Table D3 (Page 117).
ATSDR also identified a few potential exposure pathways. Those pathways elements are summarized in Appendix D--Table D4 (Page 118).
Comprehensive evaluations of pathway components and issues have defined four key exposure pathways that warrant health-related discussions (presented in the Public Health Implications Section, which follows). Those key pathways are summarized below.
In this section we will discuss the possible health effects in people associated with key completed and potential exposure pathways, evaluate state and local health databases, and address specific community health concerns. Key exposure pathways are summarized in the preceding section.
Introduction
To evaluate health effects, ATSDR compares the estimated amount of exposure for a chemical or chemicals to health guidelines, such as ATSDR's Minimal Risk Level (MRL), which are derived from human and animal studies. The MRL is an estimate of daily human exposure to a contaminant below which non-cancer, adverse health effects are unlikely to occur. ATSDR also compares the estimated amount of exposure directly to human and animal studies, which are reported in ATSDR's chemical-specific toxicological profiles. Not only do the toxicological profiles provide health information, they also provide information about environmental transport, human exposure, and regulatory status. The toxicological profiles used in the preparation of this report were arsenic, barium, beryllium, cadmium, cobalt, copper, iron, magnesium, manganese, silver, and zinc. We also used toxicological profiles for naphthalene and polycyclic aromatic hydrocarbons. Certain inorganic metals (for example, copper, manganese, chromium, magnesium, iron, and zinc) are essential to human health but may be harmful if taken in excess. We have used guidelines established by the National Academy of Science as safe and adequate dietary intake levels for those metals. No MRLs have been established for any of the radionuclides present at the Kerr-McGee site. ATSDR does have toxicological profiles for uranium, radium, radon, and thorium.
Soil Ingestion Pathway
Inorganic Metals
Many inorganic metals were found in soil, sludge, and sediment from the site and from off the site at levels that warrant some explanation. They are arsenic, barium, beryllium, cadmium, cobalt, copper, iron, magnesium, manganese, silver, and zinc. Most of these inorganic metals were at levels typically found in soil from the western United States. Occasionally, some locations had levels that are greater than those typically found. Except for lead on Property A, none of the levels of inorganic metals in soil, sediment, and sludge, however, are likely to cause harmful effects in people regardless of whether the site or off-site areas are used for industrial, commercial, or residential purposes.
The one possible exception is lead on Property A in soil and in sediment from the stock pond. (Note: the lead and possible related exposure are not associated with the Kerr-McGee site.) If wide-spread soil contamination exists at higher levels detected in limited early sampling of Property A soil (2,564 parts per million--ppm) and sediment (1,839 ppm), then if pre-school children live or play on Property A or at the pond's edge frequently (either now or in the future), they could be exposed to levels of lead that might cause harmful effects. Significant exposure could occur if the property is developed residential. Such lead exposure could cause learning problems, lower IQ scores, and damage hemoglobin, a component of blood. It's uncertain if those effects are likely because so few soil and sediment samples have been taken to date. Therefore, it's not known if lead contamination is widespread.
Drinking Water Pathway
Inorganic Metals
Drinking water contaminants and related exposures are not associated with the Kerr-McGee site. Water taken from a private well in January 1990 contained 0.054 ppm lead and 14.5 ppm iron. Two samples taken in 1995 showed lead was as much as 0.045 ppm. Since this well was not used as drinking water, no one in the house was exposed to lead or iron. In 1995, analyses of two water samples for metals (but not iron) showed lead was 0.045 ppm and nondetect, respectively.
Several water samples taken in December 1989, and January 1990, from private wells contained iron at 0.06 - 1.2 ppm. In addition, one public well used to supplement reservoir well water also contained iron ranging from 1 to 16 ppm in 1989 and 5.9 ppm in 1995 (Table 12). Iron levels in private and public well water exceed EPA's secondary MCL for iron. EPA developed the secondary MCL for iron as a guide to when drinking water might be objectionable because of taste and aesthetic characteristics. Exceeding the secondary standard for iron means that the water may smell or taste bad. It may also stain clothes.
Several other inorganic metals (arsenic, cadmium, copper, magnesium, manganese, and zinc) were found in private and municipal wells. The levels detected, however, are not harmful.
Elevated levels of sodium (greater than 20 ppm) were found in a private well being used for drinking water at the residence on Property A and also in public water supply wells used to supplement reservoir water obtained from the Big Creek watershed. (Note: sodium and related exposure are not associated with the Kerr-McGee site.) While sodium is generally non-toxic, people who are on a salt-restricted diet because of medication or because of previously diagnosed cardiovascular disease should avoid drinking water that contains sodium at levels greater than 20 ppm (25, 26). Sodium intake in such instances could lead to adverse drug reactions or could contribute to cardiovascular disease.
It's uncertain whether or not people using municipal water have been at risk from sodium exposure because the well water probably mixed with some reservoir water before distribution, which should have reduced the sodium levels.
Sludge Ingestion Pathway
2-Methylnaphthalene and Naphthalene
2-Methylnaphthalene and naphthalene, natural components of crude oil, are present in sludge on the Kerr-McGee site at a maximum level of 5,000 and 620 ppm, respectively. ATSDR has been informed that the sludge pits are being cleaned up. If for some reason the sludge pits would not be fully and adequately remediated and if pit locations later are developed for residential use, some children at play are likely to be exposed to 2-methylnapthalene and naphthalene. That exposure would occur as children, especially pre-school children, accidentally swallow particles that cling to their hands while playing. Exposure would be greater for a small percentage of pre-school children who are known to purposely swallow soil. We designate such activity as soil-pica behavior, the activity of eating non-food items. Such behavior is highest in 1 and 2 year-old children and diminishes as they approach elementary-school age. Children might also be exposed via inhalation as 2-methylnapthalene and naphthalene evaporate into the air. However, it's not possible to estimate the level of exposure.
No information in human studies and very limited information from animal studies are available about the toxic effects of 2-methylnaphthalene. One mouse study that injected 2-methylnapthalene into the peritoneum (a membranous sac that surrounds the body's internal organs) showed damage to certain cells in the lungs. One could postulate that children playing on or near sludge might breathe in 2-methylnapthalene vapors. That inhalation exposure, if high enough, might damage those cells. However, there is much uncertainty in that statement since we do not know the concentration of 2-methylnaphthalene in air above or beyond the sludge, and since we are uncertain about it's ability to damage Clara cells once inhaled.
Since naphthalene is structurally similar to 2-methylnapthalene (differs only by a methyl group), naphthalene toxicity might be used as a guide to the toxicity of 2-methylnapthalene. Combining the concentrations of 2-methylnaphthalene and naphthalene and using naphthalene's toxicity as a guide, pre-school children who accidentally swallow contaminated materials are not likely to experience any harmful effects. The same is true for adults. However, pre-school children who have soil-pica behavior might experience effects to the blood, liver, and neurological system. Some children of Asian, Mediterranean, or African origin are more sensitive to 2-methylnaphthalene and naphthalene. This is because children with those origins are likely to have lower levels of glucose-6-phosphatase, an enzyme responsible for altering naphthalene to a less toxic form (26, 27).
Benzo(a)anthracene, Benzo(a)pyrene, Chrysene, and Phenanthrene
Benzo(a)anthracene, benzo(a)pyrene, chrysene, and phenanthrene, which are present in sludge on the Kerr-McGee site, are known as polycyclic aromatic hydrocarbons or PAHs. Studies have shown that benzo(a)anthracene, benzo(a)pyrene, and chrysene are carcinogenic in animals, which suggests that they may cause cancer in humans. No evidence has shown that phenanthrene can cause cancer in humans or animals.
If for some reason the sludge pits would not be fully and adequately remediated, industrial, commercial, or residential development involving the sludge pit locations could lead to human exposure to PAHs. Such exposure, especially should the locations become residential, might increase the possibility of people getting cancer should they come in contact with the sludge contaminants. Skin contact with the PAHs in the sludge may also cause irritation, burning, inflammatory spots, eruption of blood vessels, and sensitization to sunlight.
As mentioned in the preceding section, ATSDR has not established MRLs for any of the radionuclides present at the Kerr-McGee site or for ionizing radiation. ATSDR does have toxicological profiles for uranium, radium, radon, and thorium. A general discussion about radioactivity and health is provided in Appendix E.
Overview: Gamma Radiation Exposure and Health
Gamma radiation, a very penetrating type of ionizing radiation similar to x-rays, is emitted from certain radioactive elements in the ground (and sometimes other media) and travels through the air to the human body. Emissions are continuous, and body exposure can occur at some distance from the actual contamination source. The general health effects of ionizing radiation can be divided into those that are related to dose and those that are not dose related. The effects that are not dose related possibly have a threshold (minimum dose) that must be exceeded before the effects are observed. These effects are non-stochastic or deterministic effects. The risk of developing cancer from exposure to ionizing radiation, however, may be dose related with perhaps no threshold - a stochastic or random effect.
Ionizing radiation can damage body cells in multiple ways. The radiation can damage strands of genetic material, DNA, in a cell. The cell may not be able to repair this type of damage and will die, or the cell may live on but function abnormally. If an abnormally functioning cell divides and reproduces, a mutation may develop in the tissue. The rapidly dividing cells that line the intestines and the stomach and blood cells in the bone marrow are very sensitive to ionizing radiation damage. Organ damage results from the cumulative effects on individual cells. Organ damage has been reported with doses of 25 to 500 rads (note: an annual level that is 100 to 500 times higher than estimated at the site). Acute radiation effects are seen only after doses of greater than 50 rads. When human reproductive system cells are damaged by radiation, genetic damage may occur in the offspring. The type of malformation is related to the stage of fetal development and the cells that are differentiating at the time of exposure.
Site-Specific Gamma Radiation and Effects
Radiological contamination at the site is localized within specific areas. Site area surveys using sensitive measuring instruments show ionizing radiation occurs at some of these areas at levels slightly elevated above background levels, and at some locations, including some sludge in Pit 4 (located in the northeast part of the property), at somewhat greater levels. For purposes of this discussion, ATSDR calls the areas of greater radiation "hot spots". The majority of the "hot spot" areas are located north of Deep Rock Road, which is shown on Figure 1. These areas have been posted and in many cases fenced to reduce potential exposures from inadvertent intrusion.
ATSDR concludes that ionizing radiation is a completed exposure pathway. Many of the workers and some of the other nonworker adults and children that have been on the site have been exposed without having been directly in contact with radioactive materials. In evaluations, ATSDR conservatively assumed the "hot spot" contamination to be uniformly distributed over an "area-wide" ground surface and that human receptors spend extensive time at that location. These assumptions conservatively overestimate the radiation exposure and potential for health effects. In actuality, the chances of such exposure magnitudes having occurred are remote.
For purposes of this discussion, ATSDR considers the exposure rate in roentgens to be equivalent to rem (a unit of radiation dose). Current regulatory public exposure limits to ionizing radiation are 100 millirem per year (10 CFR 20.1301). This also applies to workers who are not classified as occupational radiation workers (see 10 CFR 20.1003). Using the assumption that the contamination is uniformly distributed in the "hot spot" areas and the exposure rate (except at Pit 4) is 50 microroentgens per hour (µR/h) or about 0.05 millirem per hour, this statutory limit would be reached after spending 8 hours per day for one year (250 days) in a "hot spot" area. No adverse health effects would be expected at this dose.
Many of the hot spots, including portions of sludge at Pit 4, contain elevated levels of both ionizing radiation and radioactive material. Within the Nuclear Process Areas, the maximum ionizing (gamma) radiation levels detected exceeded 120 microroentgens per hour (µR/h). Similarly, in Pit 4 reported values were also 120 µR/h. Although the level of ionizing radiation at these locations would result in an annual dose in excess of the current 100 millirem per year limit using the above occupancy scenario, no adverse health effects would be expected as a result of the remediation activities.
Among the radionuclides, thorium-232, radium-226, and uranium-234/235/238 well exceed background levels in soils. The maximum concentrations found were 206 picocuries per gram (pCi/g) for thorium-232, 494 pCi/g for radium-226, 940 pCi/g for uranium-234, 36 pCi/g for uranium-235, and 116 pCi/g for uranium-238. These levels were not necessarily restricted to the Nuclear Process Area but typically were in areas that had been fenced to preclude inadvertent intrusion. Background concentrations for these radionuclides, excluding uranium-235, are less than 4 pCi/g. For uranium-235, the site-associated background is on the order of 0.15 pCi/g. The maximum concentrations of radionuclides in the Pit 4 sludge range from 8.3 to 34 pCi/g. Radium-228 was elevated; whereas, the radium-226 is not considered elevated in the pit. Incidental ingestion exposure by workers or others to these concentrations would not be expected to result in adverse health effects during remediation.
If for some reason sludge in Pit 4 (or any other sludge that might be similarly impacted) and other hot spots would not be fully and adequately remediated, the levels of ionizing radiation do pose a serious, long-term health effect as exposures can approach or exceed 1 rem per year for persons associated with future industrial, commercial, or residential development. Furthermore, when coupled with the possible incidental ingestion of radionuclide-contaminated sludge, these risks are increased as the radiation dose from the ionizing radiation component must be added to the radiation dose from the ingestion pathway. At this potential level of exposure the chance of leukemia, other cancers, or organ damage is greatly increased. Considering the degree of oversight by both ODEQ and NRC regarding ongoing remediation activities the chance for a future significant exposure is remote.
Uranium
The primary human studies about exposure to uranium have been on uranium miners and uranium mill workers. Those workers were exposed to high levels of uranium dust and fumes and other radioactive elements in confined conditions (28). The studies have shown there has been a statistically significant increase in lung cancer deaths among these workers. That greater incidence effect may have been attributable to the decay of uranium into radon and its further decay products or other non-radioactive constituents those workers might have inhaled.
Toxicological effects from the ingestion of uranium are the result of the action of uranium as a metal and not its radioactive properties. The primary toxic chemical effect is seen in kidney damage. Studies in rabbits, mice, and dogs showed kidney damage in a dose-related effect. The dose of uranium given in these tests is thousands of times higher than would be expected at the site. In humans, the absorption of ingested uranium is very low; an estimated 5 per cent crosses the gastrointestinal tract. The current theory is that a concentration in the kidneys equal to 3 micrograms of uranium per gram of kidney weight is necessary before kidney damage is seen. The concentrations of uranium in the contaminated areas of the Kerr-McGee site are elevated; however, at the concentrations present, health effects arising from uranium exposure are considered unlikely.
C. Health Outcome Data Evaluation
We have evaluated cancer mortality (deaths) in the area because of citizens' concerns about cancer. The Oklahoma Department of Health provided data on cancer deaths by age, sex, and type of cancer in Cushing, Payne County, and the State of Oklahoma for 1976 to 1990.
We omitted the town of Stillwater from the Payne County population because it is a college community. Having such a young population may reduce the cancer rate for Payne County. Cushing and the remainder of Payne County were selected as the study populations and Oklahoma as a reference population. Due to low number of cancer deaths in the population, we had to combine data for all 15 years to generate a cancer mortality rate. The results are presented in Appendix F, Table F1 (page 122).
No significant differences appeared between any female cancer type for Cushing when compared to Oklahoma or to Payne County.
Men in Cushing may have more deaths from prostate cancer than the State of Oklahoma. The cause of this increase is unknown. Significantly fewer male deaths occurred from lung cancer in Payne County than in Oklahoma or Cushing. Payne County may have fewer total male cancer mortalities for its population than the State of Oklahoma. It's difficult to be certain of the results of the analysis, however, because the number of cancers and the number of people in the population are small.
This evaluation of cancer rates cannot be used to determine if the Kerr-McGee site has caused cancer in people who worked there or who lived near the site. It can be used to give the reader an idea if certain types of cancer or if cancer in general are significantly elevated in Cushing or Payne County. Knowing the cancer rates can be used to decide whether or not educational efforts are warranted by educating people about life-style factors that might contribute to cancer.
D. Community Health Concerns Evaluation
During an early phase of our investigations, community members raised several concerns, which are addressed below:
While some inorganic metals were found in soil on the site and in Property A that have been shown to cause cancer at very high exposure levels, the levels in soil at the site are at or near background levels for those metals. It's unlikely that the inorganic metals will cause cancer in people under those circumstances.
The analysis of cancer statistics for Cushing and Payne County showed that women in those areas have the same cancer rates as the state as a whole. For men, the only cancer that was found to be elevated was prostrate cancer. It's not possible to determine if contaminants at the Kerr-McGee site are responsible for the elevated rate of prostrate cancer in men.
A private well on Property A and several supplemental municipal water supply wells in Cushing contained elevated levels of sodium. The source of sodium appears to be natural and not attributable to the Kerr-McGee site. While sodium is usually not harmful, people who are on a salt-restricted diet because of medication or because of previously diagnosed cardiovascular disease should avoid drinking water that contains sodium at levels greater than 20 ppm (25, 26). Sodium intake in such instances could lead to adverse drug reactions or could contribute to cardiovascular disease.
It's uncertain whether or not people using municipal water are at risk from sodium exposure because the public water supply was probably mixed with water from the reservoir, which may have reduced the sodium levels.
Gross alpha and gross beta radiation levels known in some private wells and radiation in public wells are below levels of public health concern and below Maximum Contaminant Levels (MCL) water quality criteria. Without more extensive radionuclide sampling, we cannot fully evaluate the radionuclide contamination presence or origin in private and municipal wells.
None of the several other ponds examined in the site vicinity are in the site watershed. The nearest two ponds are on adjacent property north of the Kerr-McGee site and are located spatially and topographically such that substantive contamination from the site is not likely to have occurred. Water samples obtained from that pond do not show elevated levels of the radioactive, water quality, and metals analyzed; however, organic compounds were not analyzed, and sediments were not sampled. Hence the analyses are not sufficient to confirm whether the two ponds are suitable for swimming. Sampling conducted at other ponds in the site vicinity also was limited, but those ponds are at locations that are not likely to have been affected by the site.
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