The Agency for Toxic Substances and Disease Registry (ATSDR) is a federal public health agency within the United States Department of Health and Human Services.
From the article:
“… 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.”
PUBLIC HEALTH ASSESSMENT
KERR-MCGEE REFINERY SITE
CUSHING, PAYNE COUNTY, OKLAHOMA
ATSDR reviewed investigation data and made an initial selection of contaminants that maywarrant further evaluation for public health significance. The extensive investigation programs,initial selection process, and tables of the contaminants chosen for further evaluation arepresented in Appendix C (begins on Page 36)
The contaminants identified by that process and the exposure pathways in which they occur thenwere evaluated to determine whether any may be of public health significance. Those healthsignificance evaluations identified several contaminants of possible public health concern (KeyContaminants) in certain environmental media both on site and off site. Those KeyContaminants are identified in the next paragraph.
Key contaminants that were determined to warrant health clarification discussion in the PublicHealth Implications section (Page 14) include:
- Lead in Property A soils and sediment
Note: not associated with Kerr-McGee site
- Lead, iron, sodium in some private wells
Note: not associated with Kerr-McGee site
- Iron and sodium in public wells that supplement municipal water supply
Note: not associated with Kerr-McGee site
- 2-Methylnaphthalene, naphthalene, benzo(a)anthracene, benzo(a)pyrene, chrysene, andphenanthrene in waste pit sludge on Kerr-McGee site
- Radiation on Kerr-McGee site
ATSDR has relied on laboratory data provided in the referenced documents. Not all such dataincluded quality control information. The completeness and reliability of laboratory informationcould affect the validity of ATSDR’s conclusions.
ATSDR believes that the disposal pits, radiation management areas, building remnants, anddebris do not pose physical or other personal hazards to knowledgeable workers. The potentialhazard to intruders is mitigated by the substantial fences surrounding pits and radiationmanagement areas, the fence system (at least 3 wire strands) and postings surrounding the entireproperty, and the general remoteness of the property.
ATSDR identifies human exposure pathways by examining environmental and humancomponents that might lead to contact with contaminants. A pathway analysis considers fiveelements: a source of contamination, the presence or transport of contaminants in anenvironmental 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 elementsare evident, indicating that exposure to a contaminant has occurred in the past, is currentlyoccurring, or will occur in the future. ATSDR regards people who come in contact withcontamination as exposed: for example, people who drink contaminated water, or who reside inan 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 clearlydefined 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 thefuture.
ATSDR staff (through review of site history; past, current, and future activities; and mediasampling data) have identified numerous completed past, current, or future exposure pathwayson the site, off the site on Property A, and elsewhere off site. Those completed pathwaycomponents are summarized in Appendix D in three separate tables: 1) On-Site Pathways; TableD1 (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 aresummarized in Appendix D–Table D4 (Page 118).
Comprehensive evaluations of pathway components and issues have defined four key exposurepathways that warrant health-related discussions (presented in the Public Health ImplicationsSection, which follows). Those key pathways are summarized below.
- Soil ingestion (completed exposure pathway)
1) Children and adults who reside on Property A in the past or in the future. (Note:exposure there is not associated with Kerr-McGee site), or,
2) Children and adults who occasionally may enter the Kerr-McGee property arelikely to be exposed to certain contaminants when they accidentally swallowsmall amounts of contaminated soil that clings to their hands, or
3) Adults who worked on the Kerr-McGee site and who had activities that broughtthem into contact with soil, for example, while working at the sludge pits..
- Drinking water (completed exposure pathway) — Children and adults are likely to have been exposed to elevated levels of sodium when drinking water from certain private or public wells (Note: exposure not associated with Kerr-McGee site).
- Sludge residue (potential exposure pathway) — If for some reason sludge deposits on the Kerr-McGee site are not fully and adequately remediated, after future development of the property for residential, commercial, business, or recreational use, children and adults could be exposed to certain contaminants when they accidentally swallow small amount of contaminated particles that cling to their hands.
- Radiation (completed exposure pathway) — Workers at Kerr-McGee have been exposedto radiation and some other adults and children who have entered the site have beenexposed. If for some reason, affected areas are not fully and adequately remediated, afterfuture development of the property for residential, commercial, business, or recreationaluse, children and adults could be exposed.
In this section we will discuss the possible health effects in people associated with keycompleted and potential exposure pathways, evaluate state and local health databases, andaddress specific community health concerns. Key exposure pathways are summarized in thepreceding section.
To evaluate health effects, ATSDR compares the estimated amount of exposure for a chemicalor chemicals to health guidelines, such as ATSDR’s Minimal Risk Level (MRL), which arederived from human and animal studies. The MRL is an estimate of daily human exposure to acontaminant below which non-cancer, adverse health effects are unlikely to occur. ATSDR alsocompares the estimated amount of exposure directly to human and animal studies, which arereported in ATSDR’s chemical-specific toxicological profiles. Not only do the toxicologicalprofiles provide health information, they also provide information about environmentaltransport, human exposure, and regulatory status. The toxicological profiles used in thepreparation of this report were arsenic, barium, beryllium, cadmium, cobalt, copper, iron,magnesium, manganese, silver, and zinc. We also used toxicological profiles for naphthaleneand polycyclic aromatic hydrocarbons. Certain inorganic metals (for example, copper,manganese, chromium, magnesium, iron, and zinc) are essential to human health but may beharmful if taken in excess. We have used guidelines established by the National Academy ofScience as safe and adequate dietary intake levels for those metals. No MRLs have beenestablished for any of the radionuclides present at the Kerr-McGee site. ATSDR does havetoxicological profiles for uranium, radium, radon, and thorium.
Soil Ingestion Pathway
Many inorganic metals were found in soil, sludge, and sediment from the site and from off thesite at levels that warrant some explanation. They are arsenic, barium, beryllium, cadmium,cobalt, copper, iron, magnesium, manganese, silver, and zinc. Most of these inorganic metalswere at levels typically found in soil from the western United States. Occasionally, somelocations 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 causeharmful 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.) Ifwide-spread soil contamination exists at higher levels detected in limited early sampling ofProperty A soil (2,564 parts per million–ppm) and sediment (1,839 ppm), then if pre-schoolchildren 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 exposurecould occur if the property is developed residential. Such lead exposure could cause learningproblems, lower IQ scores, and damage hemoglobin, a component of blood. It’s uncertain ifthose 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
Lead and Iron
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 notused as drinking water, no one in the house was exposed to lead or iron. In 1995, analyses oftwo 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 containediron at 0.06 – 1.2 ppm. In addition, one public well used to supplement reservoir well water alsocontained iron ranging from 1 to 16 ppm in 1989 and 5.9 ppm in 1995 (Table 12). Iron levels inprivate and public well water exceed EPA’s secondary MCL for iron. EPA developed thesecondary MCL for iron as a guide to when drinking water might be objectionable because oftaste and aesthetic characteristics. Exceeding the secondary standard for iron means that thewater 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 fordrinking water at the residence on Property A and also in public water supply wells used tosupplement reservoir water obtained from the Big Creek watershed. (Note: sodium and relatedexposure 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 previouslydiagnosed cardiovascular disease should avoid drinking water that contains sodium at levelsgreater than 20 ppm (25, 26). Sodium intake in such instances could lead to adverse drugreactions or could contribute to cardiovascular disease.
It’s uncertain whether or not people using municipal water have been at risk from sodiumexposure 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 onthe Kerr-McGee site at a maximum level of 5,000 and 620 ppm, respectively. ATSDR has beeninformed that the sludge pits are being cleaned up. If for some reason the sludge pits would notbe 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. Thatexposure would occur as children, especially pre-school children, accidentally swallow particlesthat 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 beexposed 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 availableabout the toxic effects of 2-methylnaphthalene. One mouse study that injected 2-methylnapthalene into the peritoneum (a membranous sac that surrounds the body’s internalorgans) showed damage to certain cells in the lungs. One could postulate that children playingon or near sludge might breathe in 2-methylnapthalene vapors. That inhalation exposure, if highenough, might damage those cells. However, there is much uncertainty in that statement sincewe 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. Combiningthe concentrations of 2-methylnaphthalene and naphthalene and using naphthalene’s toxicity as aguide, pre-school children who accidentally swallow contaminated materials are not likely toexperience any harmful effects. The same is true for adults. However, pre-school children whohave 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 tohave lower levels of glucose-6-phosphatase, an enzyme responsible for altering naphthalene to aless 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 sludgeon the Kerr-McGee site, are known as polycyclic aromatic hydrocarbons or PAHs. Studies haveshown 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 thatphenanthrene 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 humanexposure to PAHs. Such exposure, especially should the locations become residential, mightincrease the possibility of people getting cancer should they come in contact with the sludgecontaminants. 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 theradionuclides present at the Kerr-McGee site or for ionizing radiation. ATSDR does havetoxicological profiles for uranium, radium, radon, and thorium. A general discussion aboutradioactivity 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 fromcertain radioactive elements in the ground (and sometimes other media) and travels through theair to the human body. Emissions are continuous, and body exposure can occur at some distancefrom the actual contamination source. The general health effects of ionizing radiation can bedivided into those that are related to dose and those that are not dose related. The effects that arenot dose related possibly have a threshold (minimum dose) that must be exceeded before theeffects are observed. These effects are non-stochastic or deterministic effects. The risk ofdeveloping cancer from exposure to ionizing radiation, however, may be dose related withperhaps no threshold – a stochastic or random effect.
Ionizing radiation can damage body cells in multiple ways. The radiation can damage strands ofgenetic material, DNA, in a cell. The cell may not be able to repair this type of damage and willdie, or the cell may live on but function abnormally. If an abnormally functioning cell dividesand reproduces, a mutation may develop in the tissue. The rapidly dividing cells that line theintestines and the stomach and blood cells in the bone marrow are very sensitive to ionizingradiation damage. Organ damage results from the cumulative effects on individual cells. Organdamage has been reported with doses of 25 to 500 rads (note: an annual level that is 100 to 500times higher than estimated at the site). Acute radiation effects are seen only after doses ofgreater than 50 rads. When human reproductive system cells are damaged by radiation, geneticdamage may occur in the offspring. The type of malformation is related to the stage of fetaldevelopment 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 usingsensitive measuring instruments show ionizing radiation occurs at some of these areas at levelsslightly 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 thisdiscussion, ATSDR calls the areas of greater radiation “hot spots”. The majority of the “hotspot” areas are located north of Deep Rock Road, which is shown on Figure 1. These areas havebeen 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 theworkers and some of the other nonworker adults and children that have been on the site havebeen 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 healtheffects. 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 beequivalent to rem (a unit of radiation dose). Current regulatory public exposure limits toionizing radiation are 100 millirem per year (10 CFR 20.1301). This also applies to workerswho are not classified as occupational radiation workers (see 10 CFR 20.1003). Using theassumption that the contamination is uniformly distributed in the “hot spot” areas and theexposure rate (except at Pit 4) is 50 microroentgens per hour (µR/h) or about 0.05 millirem perhour, this statutory limit would be reached after spending 8 hours per day for one year (250days) 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 bothionizing radiation and radioactive material. Within the Nuclear Process Areas, the maximumionizing (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 radiationat 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 resultof the remediation activities.
Among the radionuclides, thorium-232, radium-226, and uranium-234/235/238 well exceedbackground 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 foruranium-235, and 116 pCi/g for uranium-238. These levels were not necessarily restricted to theNuclear Process Area but typically were in areas that had been fenced to preclude inadvertentintrusion. Background concentrations for these radionuclides, excluding uranium-235, are lessthan 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 dopose 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 tothe 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 ofoversight by both ODEQ and NRC regarding ongoing remediation activities the chance for afuture significant exposure is remote.
The primary human studies about exposure to uranium have been on uranium miners anduranium mill workers. Those workers were exposed to high levels of uranium dust and fumesand other radioactive elements in confined conditions (28). The studies have shown there hasbeen a statistically significant increase in lung cancer deaths among these workers. That greaterincidence effect may have been attributable to the decay of uranium into radon and its furtherdecay 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 ametal and not its radioactive properties. The primary toxic chemical effect is seen in kidneydamage. Studies in rabbits, mice, and dogs showed kidney damage in a dose-related effect. Thedose of uranium given in these tests is thousands of times higher than would be expected at thesite. In humans, the absorption of ingested uranium is very low; an estimated 5 per cent crossesthe gastrointestinal tract. The current theory is that a concentration in the kidneys equal to 3micrograms 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 areconsidered unlikely.
We have evaluated cancer mortality (deaths) in the area because of citizens’ concerns aboutcancer. The Oklahoma Department of Health provided data on cancer deaths by age, sex, andtype 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 collegecommunity. 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 andOklahoma as a reference population. Due to low number of cancer deaths in the population, wehad to combine data for all 15 years to generate a cancer mortality rate. The results arepresented in Appendix F, Table F1 (page 122).
No significant differences appeared between any female cancer type for Cushing when comparedto Oklahoma or to Payne County.
Men in Cushing may have more deaths from prostate cancer than the State of Oklahoma. Thecause of this increase is unknown. Significantly fewer male deaths occurred from lung cancer inPayne County than in Oklahoma or Cushing. Payne County may have fewer total male cancermortalities for its population than the State of Oklahoma. It’s difficult to be certain of the resultsof the analysis, however, because the number of cancers and the number of people in thepopulation are small.
This evaluation of cancer rates cannot be used to determine if the Kerr-McGee site has causedcancer in people who worked there or who lived near the site. It can be used to give the readeran idea if certain types of cancer or if cancer in general are significantly elevated in Cushing orPayne County. Knowing the cancer rates can be used to decide whether or not educationalefforts are warranted by educating people about life-style factors that might contribute to cancer.
During an early phase of our investigations, community members raised several concerns, whichare addressed below:
- Are the numbers and types of cancers in the area attributable to the Kerr-McGee site?
It seems unlikely that cancers in Cushing or Payne County are being caused bychemical or radiological contamination at the Kerr-McGee site. To increase therisk of someone getting cancer from environmental exposure, they would have tobe exposed to significant levels of a cancer-causing chemical or radiationfrequently for long periods (years). The most significant contamination by achemical on the site that can cause cancer is from PAHs in the sludge pits. Thepublic is not likely to be exposed to these site chemicals frequently over manyyears because residents would have to come in direct contact with sludge for PAHexposure to occur.While some inorganic metals were found in soil on the site and in Property A thathave been shown to cause cancer at very high exposure levels, the levels in soil atthe site are at or near background levels for those metals. It’s unlikely that theinorganic metals will cause cancer in people under those circumstances.
The analysis of cancer statistics for Cushing and Payne County showed thatwomen in those areas have the same cancer rates as the state as a whole. Formen, the only cancer that was found to be elevated was prostrate cancer. It’s notpossible to determine if contaminants at the Kerr-McGee site are responsible forthe elevated rate of prostrate cancer in men.
- Are the private and municipal drinking water supplies contaminated?
Private wells and certain municipal water wells in Cushing that are used tosupplement reservoir water have some inorganic metals. The levels of thoseinorganic metals are not harmful. The source of those inorganic metals does notappear to be from the Kerr-McGee site but rather they are naturally occurring inthe groundwater.A private well on Property A and several supplemental municipal water supplywells in Cushing contained elevated levels of sodium. The source of sodiumappears to be natural and not attributable to the Kerr-McGee site. While sodiumis usually not harmful, people who are on a salt-restricted diet because ofmedication or because of previously diagnosed cardiovascular disease shouldavoid 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 couldcontribute to cardiovascular disease.
It’s uncertain whether or not people using municipal water are at risk fromsodium exposure because the public water supply was probably mixed with waterfrom the reservoir, which may have reduced the sodium levels.
Gross alpha and gross beta radiation levels known in some private wells andradiation in public wells are below levels of public health concern and belowMaximum Contaminant Levels (MCL) water quality criteria. Without moreextensive radionuclide sampling, we cannot fully evaluate the radionuclidecontamination presence or origin in private and municipal wells.
- Are people being exposed to contaminants that might bioaccumulate in humans?
None of the chemicals present on the Kerr-McGee site or in Property A soils willbioaccumulate in humans through a food-chain pathway. If lead contaminationis widespread on Property A at high levels, lead could accumulate in childrenwho might live or play on that property.
- Is it safe to swim in or water livestock from area ponds?
The stock pond on Property A is in the same watershed as the Kerr-McGee siteand has been shown, through limited sampling, to contain substantivecontamination. Thus, swimming in that pond is inappropriate unless measuresare taken to clean up the pond. ATSDR is unable to comment on suitability of thepond for watering stock.None of the several other ponds examined in the site vicinity are in the sitewatershed. The nearest two ponds are on adjacent property north of the Kerr-McGee site and are located spatially and topographically such that substantivecontamination from the site is not likely to have occurred. Water samplesobtained from that pond do not show elevated levels of the radioactive, waterquality, and metals analyzed; however, organic compounds were not analyzed,and sediments were not sampled. Hence the analyses are not sufficient to confirmwhether the two ponds are suitable for swimming. Sampling conducted at otherponds in the site vicinity also was limited, but those ponds are at locations thatare not likely to have been affected by the site.
- Are the numbers of illnesses and deaths in area neighborhoods attributable to the Kerr-McGee site?
It seems unlikely that chemical or radiological contamination at the Kerr-McGeesite caused illnesses and deaths in neighborhoods near the site.
- Should citizens monitor their radiation doses with radiation badges?
Radiation levels present on the Kerr-McGee site, at their fenceline, and in off-siteareas would not indicate that any type of personnel monitoring would benecessary.