PUBLIC HEALTH ASSESSMENT
IDAHO NATIONAL ENGINEERING AND ENVIRONMENTAL LABORATORY (U.S. DEPARTMENT OF ENERGY)
[a/k/a IDAHO NATIONAL ENGINEERING LABORATORY (USDOE)]
IDAHO FALLS, BUTTE, CLARK, JEFFERSON AND BIN COUNTIES, IDAHO
ATSDR's PHAs are exposure, or contact, driven. A release of a hazardous waste does not always result in human exposure. Rather, people are exposed to a contaminant such as those identified at the INEEL site only if they come in contact with it; they might be exposed by breathing, eating, or drinking a substance containing the contaminant, by skin contact with a substance containing the contaminant, or from close proximity to gamma emitters. ATSDR concentrated its review on the time period 1987-2000. Exposures prior to 1987 are being estimated by the CDC dose reconstruction project.
This section evaluates the estimated exposure doses for contaminants of concern for completed and potential exposure pathways for potentially affected populations. In these evaluations, ATSDR considered the frequency and duration of the estimated exposures. For populations affected by more than one pathway, ATSDR also considered the combinations of contaminants and exposure routes. This section also presents the potential health effects from each contaminant of concern in a completed pathway.
ATSDR considered characteristics of the exposed populations–such as age, sex, nutritional status, genetics, lifestyle, and health status–that influence how a person absorbs, distributes, metabolizes, and excretes contaminants. Where appropriate, ATSDR includes these characteristics in the contaminant-specific discussions.
In evaluating public health hazards, ATSDR first tries to determine exposure by carefully evaluating the elements of an exposure pathway that might lead to human exposure. These elements include (1) a source of site-related contamination, such as drums or waste pits; (2) an environmental medium in which the contaminants might be present or from which they might migrate, such as groundwater or soil; (3) points of human exposure, such as drinking water wells or gardens; (4) routes of exposure, such as breathing, eating, drinking, or touching a substance containing the contaminant; and (5) a receptor population. (Figure 4 explains exposure pathway evaluation in more detail.) ATSDR then identifies an exposure pathway as completed or potential, or else eliminates that pathway from further evaluation. A completed exposure pathway exists if all elements of human exposure link the contaminant source to a receptor population. A potential pathway is one that ATSDR cannot rule out, even though one of the necessary elements is not apparent.
If a completed or potential exposure pathway exists, ATSDR then considers whether chemicals of concern were present, are present, or are expected to become present. (No matter how much of a contaminant of concern is present, a public health hazard exists only if people come in contact with, or are otherwise exposed to, harmful levels of that contaminant.)
Following the strategy outlined above, ATSDR identified completed and potential exposure pathways by which the public could be exposed to contamination specifically associated with INEEL. All of these involve workers and visitors drinking INEEL drinking water. The following table (Table 5) shows all of the exposure pathways. A discussion about which pathways are completed, potential or eliminated begins on Page 41.
Table 5. Exposure Pathways Evaluation Table
| Pathway Name | Exposure Pathway Elements | Comments | |||
| Point of Exposure | Route of Exposure | Potentially Exposed Population | Time Frame of Exposure | ||
| Completed Exposure Pathways | |||||
| Groundwater/ Drinking Water | Taps served by wells at the CFA | Ingestion | On-site workers and sporadic visitors | Past | Past: Elevated levels of tritium were detected in well CFA#1 during the mid- to late-1980s. Workers and visitors who drank water supplied by these wells could have been exposed to radionuclides, but not at high enough levels to make them sick. Currently, the INEEL water supply meets safe drinking water standards. |
| Potential Exposure Pathways | |||||
| Groundwater/ Drinking Water | Drinking water supply wells and distribution system | Ingestion | On-site workers and sporadic visitors | Past | Past: Monitoring since the 1970s has revealed that the groundwater beneath the site is contaminated with a variety of non-radiological contaminants and radionuclides. ATSDR did not review groundwater and drinking water data for early years of operation. Therefore, it is not known with certainty whether people at the INEEL could have been exposed to contaminants when they drank water in the past (before the 1970s). |
| Eliminated Pathway | |||||
| Groundwater/ Drinking Water | On-site wells and off-site private drinking wells | Ingestion, skin contact, and inhalation | On-site workers and off-site residents | Current and potential future | On-site production well water is being and will be monitored to ensure that water delivered to the taps is safe for drinking. Any groundwater contamination is expected to be greatly diluted before reaching off-site areas. |
| Surface Waters | Surface water | Ingestion and dermal contact | Workers or off-site residents | No likely past or current exposure, or potential future exposure | On-site surface water is not used for recreation. Surface water from on site does not directly affect surface water off site, because surface water flow is directed toward INEEL. Low levels of radionuclides, not specifically related to INEEL, have been detected in off-site surface water at levels below CVs. Infrequent and brief contact should not cause health effects. |
| Soils | Potential contact with soils during a site visit or hunt | Ingestion, dermal contact, and inhalation | Workers, occasional site visitors, or hunters | Limited past worker exposure. No likely current or potential future exposure | Public access is restricted at all facility operation sites. ATSDR assumes that workers in these areas are protected from high exposure by guidelines mandated by the Occupational Safety and Health Administration (OSHA). Minimal soil contamination is expected in the limited areas of public access. Low levels of radionuclides, unrelated to INEEL, have been detected in off-site soil. Brief, infrequent contacts are not hazardous. |
| Air | On-site work areas | Air | On-site workers, sporadic visitors, nearby off-site residents | Limited past worker exposure. No likely current or potential future exposure | The Draft Historical Dose Reconstruction for Air Releases from the ICPP, found that the ICPP contributed only a fraction of the thyroid dose as that from the Nevada Test Site. Air pollutants have been detected at several facilities on site. No public exposure has occurred or is occurring, because access is restricted at all facility operation sites. ATSDR assumes that workers in the area are protected from high exposure by OSHA-mandated guidelines. Very low levels of non-radiological contaminants and radionuclides, unrelated to INEEL, have been detected in off-site ambient air. Brief, infrequent contacts are not hazardous. |
| Ambient Radiation | Off-site work areas, off-site locations | Whole body | On-site workers, sporadic visitors, nearby off-site residents | Possible past worker exposure. No likely current or potential future exposure | Gamma radiation readings were high near certain INEEL facilities. The public is restricted from these areas, and ATSDR assumes that workers are protected from high exposure by OSHA-mandated guidelines. Off-site levels do not vary greatly between nearby and distant locations nor from estimated natural background effective doses, and the levels are insufficient to affect public health. |
| Biota | Off-site work areas | Ingestion | Residents of neighboring residential areas | No past, current, or potential future | Radionuclides have been detected in crops grown off the site and also in the muscles of livestock raised at the site and game grazing there. The levels of radionuclides were similar between nearby and distant locations and consistent with background concentrations. |
Past Exposure of Workers to Tritium in INEEL Drinking Water
During the mid- to late-1980s, tritium was detected at levels above EPA's MCL–20,000 pCi/L–in a supply well in the CFA. (Information is lacking on the concentrations that might have been in the distribution system that fed site taps during this period. But because the distribution system was supplied by at least 2 wells, water from a well exceeding a sample was always diluted by one or more wells that did not.) Workers and visitors to this area who drank water from this supply were exposed to levels of tritium. The wells were never used by the general public nor by surrounding communities as a drinking water supply. Currently, the levels of tritium in the CFA wells (and distribution system) are safely below EPA's MCL.
Past Exposure of Workers to INEEL Drinking Water Contaminants
Elevated levels of a variety of non-radiological contaminants (primarily VOCs and metals) and radionuclides (primarily tritium and strontium-90) have been detected in on-site groundwater since the early 1970s. Elevated levels of VOCs have also been detected in on-site production wells, but not in samples taken from the distribution system that feeds site taps. Because the groundwater has been contaminated for a long time and the site water supply has relied solely on groundwater, ATSDR has determined that on-site groundwater is a potential pathway of past exposure. Currently, no exposure to harmful levels of contaminants is occurring via the groundwater/drinking water pathway. INEEL monitors its drinking water to ensure that it meets safe drinking water standards.
ATSDR has not identified any other complete or potential exposure pathways. For other pathways, (1) exposure to the general public has been prevented and/or (2) no site-related contamination is present and/or the measured levels are consistent with background concentrations. Specifically:
Non-Radiological Contamination
If a person is exposed to a contaminant, several factors determine the type and severity of health effects associated with that exposure. These include exposure dose (how much of the substance is taken into the body), frequency (how often), and duration (how long); the route of exposure (breathing, eating, drinking, or skin contact); and the multiplicity of exposure (the combination of contaminants and pathways involved). Once exposure takes place, characteristics such as age, sex, nutritional status, genetics, lifestyle, and health status of the exposed individual influence how the individual absorbs, distributes, metabolizes, and excretes the contaminant. Together, those factors and characteristics determine the health effects that might result from exposure to a contaminant.
After identifying exposure pathways, ATSDR considers information about exposures in light of scientific information from the toxicological and epidemiologic literature. ATSDR may estimate exposure doses, which are estimates of how much contaminant a person is exposed to on a daily basis. When estimating exposure doses, ATSDR looks at many variables, including contaminant concentration, exposure amount, exposure frequency, and exposure duration. For example, exposures in the workplace are different from those in a residential setting.
ATSDR may compare estimated exposure doses to standard toxicity values. For noncancer effects, ATSDR uses ATSDR's minimal risk levels (MRLs) and EPA's reference doses (RfDs) to eliminate exposures that are not expected to result in adverse health effects. Chronic MRLs and RfDs estimate what level of daily human exposure to a substance is likely to pose no appreciable risk of adverse noncancer effects over a specified duration. Chronic MRLs and RfDs are values based on the levels of exposure reported in the literature that represent no-observed-adverse-effect levels (NOAELs) or lowest-observed-adverse-effect levels (LOAELs) for the most sensitive outcome for a given route of exposure (e.g., inhalation, ingestion). Uncertainty (safety) factors are applied to NOAELs or LOAELs to account for variation in the human population and the uncertainty involved in extrapolating human health effects from animal studies. ATSDR then reviews toxicological and epidemiological literature to evaluate the weight of evidence for adverse effects.
Comparison values and estimated dose comparisons allow ATSDR to decide which substances are present at such low levels that they are not expected to cause harm, and for which ATSDR can therefore confidently decline further evaluation. The substances not eliminated, and for which there are completed or potential pathways, are further considered in this section. When ATSDR evaluates a substance's potential to make people ill, the agency looks at site-specific factors that influence likely exposure doses. The agency also re-examines relevant scientific literature about the substance (and sometimes related substances) and how observations from the literature relate to the conditions of exposure at the site. ATSDR explores probable speciation, bioavailability, environmental fate and transport, cultural practices, the means by which experimental animals are exposed compared to how local populations might be exposed, how occupational levels and routes of exposure compare to levels and routes of exposure for the public, and many other factors.
ATSDR also evaluates the likelihood that site-related contaminants could cause cancer in people who would not otherwise develop it. To screen for the potential for cancer to occur, ATSDR uses cancer slope factors (CSFs) that define the relationship between exposure doses and the likelihood of an increased risk of developing cancer over a lifetime. But CSFs are developed by use of data from studies of animals or humans exposed to doses much higher than those typical of exposures to contaminated air, water, or soil. When evaluating the potential for cancer to occur, ATSDR must consider the relevance of such extrapolations from high exposure doses administered in animal studies to the lower exposure levels typical of human exposure to environmental contaminants.
Built into the CSF derivation is the assumption of a linear-no-threshold (LNT) model that assumes that the dose is proportional to the probability of cancer from the high doses used in the laboratory down to the doses encountered in the environment. LNT assumes that natural defenses are not effective against cancer at lower doses. A CSF represents the upper-bound estimate of the probability of developing cancer at a defined level of exposure. CSFs tend to overestimate the actual risk in order to be protective in screening and to avoid the risk of missing potentially significant exposures that should be evaluated.
ATSDR also considers the cancer effect levels (CELs) reported in the literature. A CEL is the lowest dose of a chemical in a study or group of studies that was found to produce increased incidences of cancer (or tumors).
Consumption of Volatile Organic Compounds in Drinking Water at INEEL in the Past
In the past, TCE and carbon tetrachloride (both volatile organic compounds, or VOCs) in some INEEL production wells (RWMC #1, TSF #1, and TSF #2) exceeded ATSDR CVs and EPA MCLs for drinking water. The production wells fed into a facility , but not site-wide distribution system in which the water from each production well was diluted by the water from other production wells. The diluted water in the separate distribution systems was used for drinking. There are no data showing that contamination in any of the facility distribution systems exceeded ATSDR CVs or EPA MCLs for drinking water.
To determine whether drinking water containing carbon tetrachloride or TCE had the potential to increase adverse health outcomes, ATSDR estimated exposure doses. In estimating to what extent people might be exposed to contaminants, ATSDR used assumptions about how much contaminated water they drank and how often they drank it. The assumption was that the average contaminant concentrations in people's drinking water were equal to the maximum detected concentrations in the wells, rather than the lower maximum concentrations found at drinking water taps. ATSDR assumed that an adult consumes 2 liters of water every day for 365 days each year. These assumptions allowed ATSDR to estimate the highest relevant exposure dose and to determine whether health effects could occur.
The estimated exposure doses for either a child or an adult were below its RfD for carbon tetrachloride, 0.0007 milligrams per kilogram of body weight per day (mg/kg/day). The RfD for carbon tetrachloride was derived from a laboratory study that found a NOAEL of 1 mg/kg/day–more then 50,000 times greater than the doses ATSDR estimated (ATSDR 1994).
No chronic MRL or RfD currently exists for TCE. For this reason, ATSDR reviewed the available toxicologic literature to determine possible adverse effects associated with exposure at doses estimated for this pathway. On the basis of this review, the exposure doses ATSDR estimated for TCE are several orders of magnitude lower than the lowest doses that, according to the toxicologic literature, can produce noncancer effects in experimental animals administered oral doses of TCE (ATSDR 1997).
Remember that ATSDR assumed that the water in the distribution system could have averaged as high as the maximum found in one well feeding the system and that people received all their drinking water from this system. This was an overestimate of actual exposure, because lower contaminant concentrations have been found in the affected wells, the distribution system drew from uncontaminated wells in addition to the contaminated ones, and people ingest water from many sources (e.g., prepackaged juices, soda, water supplies at the workplace). Therefore, ATSDR concludes that drinking water containing the highest detected levels of TCE reported in the production wells is not expected to result in adverse noncancer effects.
TCE has been shown to cause cancer in laboratory animals given large doses. The link between cancer in humans and TCE in drinking water is controversial, however. Available studies are inconclusive, and the data are inadequate to establish a link. EPA is currently reviewing the scientific literature to determine how to classify TCE's carcinogenicity.
ATSDR compared doses estimated for exposed workers or visitors to doses estimated not to result in cancer. ATSDR assumed that people were exposed to the maximum detected concentrations of carbon tetrachloride (5.5 ppb) and TCE (15 ppb) and that exposure occurred daily over the entire exposure period. This is an overestimate of actual exposure, for people would have also ingested water from other sources.
Using these exposure assumptions, ATSDR determined that the levels of VOCs found in the drinking water supply systems did not pose a health threat to INEEL workers or the surrounding community.
For radiological contaminants, ATSDR uses information on radiation exposure and its effects, as related to environmental levels. This information comes from federal agencies, including EPA, the US Department of Energy (DOE), and the Nuclear Regulatory Commission (NRC). ATSDR also uses other publicly available data sources and recommendations on radiation dose limits. The National Council on Radiation Protection and Measurements (NCRP), the International Commission on Radiological Protection (ICRP), and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) develop these sources.
Consumption of Tritium in Drinking Water at INEEL in the Past
People were exposed to tritium in drinking water from on-site water supply wells in the past; however, those exposures did not pose any health risk to workers or site visitors. Tritium concentrations in drinking water in the CFA were measured as high as 38,900 pCi/L in 1987. This was above EPA's MCL of 20,000 pCi/L; therefore, ATSDR evaluated the estimated dose.
If a full-time worker in the CFA were to drink 2 liters of this water daily for 7 days per week and 52 weeks per year, that worker would receive less than 2.6 millirems of whole-body dose in that year, or about 2.0% of the whole-body radiation background dose. This dose estimate is very protective, because it was calculated from the historic maximum tritium concentration and it assumes that the workers drank all their water from the contaminated well at the CFA. Any part-time worker or visitor to the site would receive only a small fraction of this already insignificant dose.
Health Outcome Data Evaluation
The ATSDR public health assessment process has not been able to find evidence of releases of substances to the public at levels that might be expected to result in any ill health. However, to address community concerns, ATSDR evaluated data for six counties adjacent to INEEL for the occurrence of congenital anomalies (birth defects) and for cancer incidence and mortality, comparing the data with data for the state of Idaho as a whole. This comparison allowed ATSDR to determine whether certain health conditions are unusually common in the six counties, but it did not provide any information about the possible causes of birth defects and cancer.
Using exposure data covering the period 1987-2000, ATSDR has not identified any populations near INEEL that were or are being exposed to levels of contaminants that would be expected to result in acute or chronic health effects. However, to address community concerns about various health outcomes reported in the vicinity of INEEL, and to consider latency periods for potential past exposures, ATSDR evaluated health outcome data from several existing vital records and disease surveillance databases. As part of the evaluation process, ATSDR reviewed vital record and birth defect information from the Idaho Department of Health and Welfare's Center for Vital Statistics and Health Policy. ATSDR obtained the assistance of the INEEL Health Effects Subcommittee, the Idaho Division of Health (Bureau of Environmental Health and Safety and the Center for Vital Statistics and Health Policy), and the Cancer Data Registry of Idaho.
ATSDR examined records for six counties in the vicinity of INEEL (Bannock, Bingham, Bonneville, Butte, Clark and Jefferson). ATSDR's evaluation of cancer rates for the counties of concern indicated that the types of cancers commonly associated with radiological and chemical exposures are within the range of what would be expected on the basis of comparisons with the state of Idaho. Rates of certain cancers, cases, or deaths were less than expected, and some were greater than expected. In most instances, the differences were not statistically significant. Most of the small increases in cancer rates were likely a result of random variability, since there did not appear to be any consistent increases across counties or within counties (e.g., although breast cancer incidence was significantly increased in Clark County, it was significantly decreased in the more populous Bingham County, compared to the incidence in the rest of the state).
ATSDR identified community health concerns through meetings with community members, state and local officials, and INEEL personnel. ATSDR also reviewed site documents, including Community Relations Plans. Concerns raised during these interviews are discussed and addressed below: transuranic waste, operations of an incinerator, high cancer rates, Pit-9, the SL1 Reactor accident, contaminated on-site water supply wells, and reburial of plutonium over the aquifer.
Operations of a Transuranic Waste Incinerator
DOE has placed a moratorium on construction and operation of incinerators, pending an evaluation of alternative technologies. If INEEL incinerates transuranic wastes in the future, it will do so at its advanced mixed waste treatment plant. If that happens, health and safety issues will be addressed: the incinerator's emission control system will be set up to filter ultrafine particles of plutonium.
Choices about particular remedial actions at particular sites are made by federal and state regulatory agencies other than ATSDR. These agencies must consider public health implications along with other risk management considerations. If requested, ATSDR can review the actual trial burn data (stack emissions data) and/or ambient air monitoring data to evaluate the potential public health implications of this facility. ATSDR's "Public Health Overview of Incineration as a Means to Destroy Hazardous Waste" is available at ATSDR's webpage at: http://www.atsdr.cdc.gov/HAC/hwincin.html
While ATSDR does not endorse or promote the use of any particular technology, ATSDR believes that properly designed and operated incinerators can destroy or decontaminate certain kinds of hazardous wastes (primarily organic contaminated wastes) in a manner that is protective of public health. Incinerators are neither inherently safe nor unsafe.
High Cancer Rates in the Counties Surrounding INEEL
ATSDR's evaluation of cancer rates for the counties surrounding INEEL found that certain cancer types occurred more often than expected. Sometimes the differences were statistically significant. On the other hand, other types of cancer occurred less often than expected, and sometimes these differences were also statistically significant.
For males, significant increases in cancer rates in a single county were seen for bone and joint cancers, prostate cancer, and acute lymphocytic leukemia. For women, significant increases were seen in brain and breast cancer rates in a single county. Significant decreases in the incidence of certain cancers for men (total leukemia and acute lymphocytic leukemia) and for women (thyroid and breast cancer) were observed for a single county when compared to the state's experience. There were also significant decreases in rates for certain cancers (e.g., lung and bronchus cancer) among men and women across multiple counties. Overall, both men and women had higher rates for some cancers and lower rates for others compared to the state's rate, with some bias toward negative deviations.
Status of Cleanup Measures at Pit 9
Pit 9 was operated as a waste disposal pit from November 1967 to June 1969.
(See Figure 4. Pit 9 Aerial View.) It was used to dispose of approximately 110,000
cubic feet of transuranic waste from the Rocky Flats Plant and additional low-level
wastes from waste generators located at the INEEL. The total volume of the pit
is approximately 250,000 cubic feet of overburden, 150,000 cubic feet of packaged
waste, and 350,000 cubic feet of soil between and below the buried waste. Most
of the transuranic waste consists of drums of sludge (contaminated with a mixture
of transuranic waste and organic solvents), drums of assorted solid waste, and cardboard boxes
containing empty contaminated drums.
Lockheed Martin Advanced Environmental Systems (LMAES), the subcontractor chosen for Pit 9 cleanup, was terminated for default on June 1, 1998, by INEEL contractor Lockheed Martin Idaho Technologies Company. The Pit 9 interim action was intended to provide information about methods for retrieval and treatment of buried transuranic waste and information on the status of contaminant migration and waste characteristics. After LMAES began its work slowdown in the summer of 1997, it became clear that a contingency plan was needed to assure that these objectives could be met. The litigation regarding LMAES has negatively impacted implementation of the contingency plan.
The clean-up of Pit 9 has recently been fast tracked. On July 30, 2002 workers began bolting and welding together a steel shoring box to be fitted around the perimeter of the dig zone in a small portion of Pit 9. In April of 2002, the DOE agreed with the state of Idaho and the EPA to start construction at Pit 9 by Nov. 30, 2002.
Much of the plutonium-contaminated waste in Idaho came from the fabrication of plutonium weapons parts at the Rocky Flats Plant near Denver, Colorado, and other weapons facilities. Waste that is stored above ground will eventually be moved to the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico. Disposal of the waste that was buried before 1970 will be addressed under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Currently, the reburial of plutonium is on hold.
ATSDR, in its consultation on the Pit 9 remedial action plan dated September 1993, recommended not going through with the planned action, because the cleanup levels would not be protective of public health.
Exposures That Resulted from the SL-1 Reactor Accident
The Stationary Low-Power Reactor No. 1's (SL-1's) mission was to provide power to radar stations along the northern perimeter of North America; a series of such stations was known as the Defense Early Warning Line. The design work was done by Argonne National Laboratory in 1955-1956 under the name Argonne Low Power Reactor. The Army's designation for the plant, SL-1, indicates that the plant was a stationary, low-power reactor and that it was the first of its kind.
SL-1 and its planned successors did not include a conventional reactor containment structure. Because they were designed for deployment in remote areas, it was not thought to be necessary. Instead, the reactor building was a simple steel cylinder with quarter-inch-thick walls. It was 48 feet high and 38.5 feet in diameter. No special provisions were made to ensure that the building would be airtight.
The accident occurred on January 3, 1961, at the Atomic Energy Commission's National Reactor Testing Station near Idaho Falls, Idaho. The cause of the accident was most likely operator error. A technician must have manually withdrawn one of the control rods; rapid boiling of water in the channel caused the rod to be ejected with great force. The result was a power excursion, fuel failure, and release of fission products.
Three technicians were working at SL-1 that night. They all died, making this the first fatal accident caused by a nuclear fission reactor outside the former Soviet Union. There was a fatality associated with the September 1983 accident at the RA-2 reactor in Argentina. Though the victims all received lethal doses of radiation, two died from other injuries before they could die from the radiation. Monitoring for radiation releases from the site began almost immediately. Calculations, completed later, indicate that approximately 10 curies had been released by early morning on January 4, 20 curies by the morning of January 5, and a total of 50 more curies between January 6 and January 30, 1961.
According to calculations conducted at the time, about 99.99% of the total fission product inventory in the core was retained inside the reactor building, even though it was not designed as a containment facility. During the recovery period, 23 people received radiation doses greater than 3 rem. Of those, three received total whole body doses in excess of 25 rems, but none received enough to display any near-term symptoms (Thompson 1973).
Potential Health Threats Posed by Contaminated Water Supply Wells
In the past, VOCs and tritium were detected in INEEL drinking water supply wells at levels above screening comparison values, but drinking the water at INEEL would not pose any health risks to on-site workers or to the sporadic visitor. One reason is that people did not drink directly from the drinking water well, but rather from drinking water distribution systems in which the water from the contaminated well was diluted by water from uncontaminated wells. Comparison values are designed to be very protective of people (including children) over a lifetime of drinking water. Because of a large margin of safety built into the comparison values, the worker's or sporadic visitor's lifetime intake would be much lower than the levels shown to cause health effects.
Monitoring to date has confirmed that no contamination has migrated to any off-site drinking water supply wells. Groundwater moves south-southwest from INEEL toward Minidoka, about 73 miles away (Johnson 2000). It would take between 50 and 220 years for the groundwater to reach the town, at which point the concentrations in the plume would be greatly diluted–less than 0.02% of the original value.
Exposure to Plutonium That Is Being Reburied over the Snake River Aquifer at INEEL
All reburial activities at INEEL are in landfills monitored for leakage. The only plutonium that would be permitted for reburial on site would be at concentrations below the WIPP acceptance criteria of 100 nanocuries per gram. Plutonium was once thought to be insoluble and not likely to migrate through soil. We now realize that colloids of plutonium tend to move through soil more readily than previously thought. This is still not a health threat, because the plutonium is not in a bio-available form.
ATSDR recognizes that the unique vulnerabilities of infants and children demand special emphasis in communities faced with contamination of their water, soil, air, or food. Children are at greater risk than adults from certain kinds of exposures to hazardous substances emitted from waste sites and emergency events. In general, children are more likely to be exposed because they play outdoors and they often bring food into contaminated areas. They are shorter than adults, which means they breathe dust, soil, and heavy vapors close to the ground. Children are also smaller, so they receive higher doses of chemical exposure proportional to their body weight. The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Most importantly, children depend completely on adults for risk identification and management decisions, housing decisions, and access to medical care.
Contaminants have been detected in INEEL drinking water wells in the past. Children probably never visited the operational portions of INEEL served by the affected wells. People did not drink directly from the drinking water wells, but from drinking water distribution systems in which the water from contaminated wells was diluted by water from uncontaminated wells. A child who visited the area could have had only sporadic, indirect exposure to drinking well water. Comparison values that may have been exceeded in drinking water are designed with a large margin of safety to protect people (including children) from prolonged, continuous exposure for a lifetime of drinking water 24 hours per day, 7 days per week, and 52 weeks per year. A child visiting the site would be expected to take in far less than the protected intake rates. Because of the margins of safety built into the comparison values, the child's lifetime dose would be orders of magnitude below doses shown in the scientific literature to cause harm to the most sensitive species.
ATSDR also attempted to identify populations of children in the vicinity of INEEL and any public health hazards threatening these children. Approximately 73 children under the age 6 and younger live within 10 miles of the INEEL facilities. ATSDR determined, however, that harmful exposures are not expected to occur, because children cannot access areas of concern or locations of contamination at INEEL and no harmful exposures associated with INEEL are specific to children at boundary community schools, residential areas, or recreational areas. Following a careful evaluation of these pathways as they relate to children, ATSDR determined that no harmful exposures have occurred in the past, nor are they likely to occur either now or in the future. These potential exposure pathways are discussed in the "Pathways Evaluation" section of this document.
On the basis of our evaluation of available environmental information, for the period 1987-2000, ATSDR categorized the exposure situations at INEEL as "no apparent public health hazard". ATSDR concluded that although there have been exposures in the past, no adverse health effects are expected. Conclusions regarding specific health concerns are as follows:
The Public Health Action Plan for the INEEL contains a description of actions to be taken by ATSDR and other government agencies at and in the vicinity of the site after the completion of this public health assessment. The purpose of this Public Health Action Plan is to ensure that this public health assessment not only identifies public health hazards but also provides a plan of action designed to mitigate and prevent adverse human health effects from exposure to hazardous substances in the environment. If additional information for the INEEL site becomes available, that may change the conclusion of this PHA, human exposure pathways should be reevaluated, and these conclusions and recommendations should be amended, as necessary, to protect public health.
Authors
Michael Brooks, MSHP, CHP
Senior Health Physicist, Lead Health Assessor
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
ATSDR
Jo A. Freedman, Ph.D., D.A.B.T.
Toxicologist
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
ATSDR
Steve Martin, M.B.A.
Data Analyst, Federal Facilities Information Management System
Office of Program Operations and Management
Information Resources Management Branch
ATSDR
Reviewers
Sandra Isaacs
Chief, Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
ATSDR
Rita Ford
Chief, Energy Section
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
ATSDR
ATSDR Region X Representative
Richard W. Robinson
Environmental Protection Specialist
Seattle, WA
Peer Reviewers
James E. Watson, Ph.D.
University of North Carolina at Chapel Hill
Professor, Department of Environmental Sciences and Engineering
Sydney W. Porter, CHP
Porter Consultants, Inc.
Ardmore, PA
David J. Tollerud, M.D., M.P.H.
University of Louisville
Associate Director, Institute for Cellular Therapeutics
Director, Specimen Repository Core Facility
Clinical Professor, School of Medicine
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