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PUBLIC HEALTH ASSESSMENT

FEED MATERIALS PRODUCTION CENTER (US DOE)
[a.k.a. FERNALD ENVIRONMENTAL MANAGEMENT PROJECT]
HAMILTON AND BUTLER COUNTIES, OHIO

POTENTIAL EXPOSURE PATHWAYS

Surface Water Pathway

Background

Liquid wastes from the Fernald site are transported to off-site areas at two primary locations, Manhole 175 and the storm sewer outfall ditch. These off-site discharge points are shown in Figure 6. The combined effluent from the site discharges through Manhole 175, at the sewage treatment plant, into the Great Miami River located east of the site about 1.2 miles downstream from the city of Ross. The storm sewer outfall ditch (SSOD) discharges into a branch of Paddy=s Run Creek at the western site boundary (Killough et al. 1998b).

Manhole 175 is the final discharge point for major waste streams leaving the facility. During the years of production, each of the individual production plants had collection sumps and treatment equipment to remove uranium from the process waste water. Waste water from each plant was sampled and analyzed to ensure that the uranium concentration was within allowable regulatory limits. The filtrate was then pumped to the General Sump for discharge through Manhole 175 to the Great Miami River. The General Sump consisted of several receiving and settling tanks. The settling tanks were used to reduce the release of contaminants into the Great Miami River (Killough et al. 1998a).

Paddy=s Run Creek is a small stream with intermittent flow lying along the western boundary of the site. Generally, there is surface flow in the creek from January to May. The remainder of the year, the creek bed is dry except for intermittent flow following heavy rains. Discharges to Paddy=s Run from the facility originate from overflow of the SSOD and from stormwater (or surface water) runoff from the on-site production area on the western side of the property. The creek joins the Great Miami River approximately 1.5 miles south of the facility. The Great Miami River is a turbulent, flowing stream all year round and supports a variety of fish and wildlife.

Before 1955, all runoff from the site went directly to Paddy=s Run Creek. In 1955, the storm sewer lift station was installed to collect runoff water collected in the storm sewer system. The runoff water passed through the storm sewer lift station before discharging through Manhole 175 to the Great Miami River. Because the storm sewer lift station was not connected to the production facilities, any chemical or radioactive contaminants in surface runoff were assumed to be from leaks and spills (Killough et al. 1998a).

Figure 6 - Surface water discharge points from the Fernald site to Paddy's Creek and the Great Miami River
(Reference: Killough et al. 1998b)

Throughout the 1950s and 1960s, daily storm sewer samples continued to reflect spills and leaks of radioactive process effluents and chemicals from various portions of the site, including the pilot plant and waste pit area (Voilleque et al. 1995). When the capacity of the storm sewer lift station was reached, water overflowed through the SSOD to Paddy=s Run. Flow to the storm sewer system, and ultimately to Paddy=s Run Creek, was quite variable and depended on total rainfall and rainfall patterns (Killough et al. 1998a). The facility monitored flow and uranium concentrations in the SSOD at a point downstream of its confluence with Paddy=s Run Creek. However, there were additional, unmonitored releases to Paddy=s Run Creek (due to surface flow from the western part of the site) at points north of its confluence with the SSOD (Killough et al. 1998a).

Estimates of uranium releases to the Great Miami River and Paddy=s Run Creek are relatively well known compared to other pathways of exposure, such as air (Killough et al. 1998a). The greatest magnitude of releases to surface water occurred in the early 1960s. During the early 1960s, the average quantity of uranium released to the Great Miami River was estimated to be 5 times greater than the quantity released to Paddy=s Run Creek (Killough et al. 1998a). Uranium releases to the river and creek steadily declined from the early 1970s to 1988 due to a decrease in production and improvements in the effluent handling system on site (Voilleque et al. 1995). For example, the facility installed a surface water retention basin (SWRB) in 1986 to reduce the volume of effluent entering the SSOD from the site.

Uranium was the primary material processed at the Fernald facility, although some thorium processing occurred at various times throughout the operation history (from 1951 to 1988). Consequently, the majority of surface water releases from the Fernald facility were uranium and thorium. Smaller releases of radium 228 and radium 224 (decay products of thorium 232), and of radium 226 (decay product of uranium 238), also occurred. Other radionuclides, such as technetium 99, neptunium 237, and plutonium 239, were released in the processing of recycled uranium that was not completely separated from the fission and activation products before it was used by the facility as feed material. Recycled uranium was processed at the Fernald facility beginning in 1962 (Voilleque et al. 1995).

The types of uranium used at the facility, and thus discharged to nearby surface waters, changed over the years of production. Normal or natural uranium represented the greatest fraction of uranium in the releases to the Great Miami River from 1951 to 1967 and from 1970 to 1976. Releases of enriched uranium were minor until 1964; between 1964 and 1971, the percentage of enriched uranium fluctuated from 20% to 60% of all uranium released to the river. Only a small fraction of depleted uranium was released to the river until 1977; the percentage rose to 80% to 90% of the total uranium in effluents after 1977 (Voilleque et al. 1995).

Environmental Data

Beginning in the 1950s, the facility regularly measured uranium concentrations and volumes in liquid effluent released from the site to the Great Miami River. The facility collected composite samples from the liquid effluent released to the river, and analyzed them for uranium, on a daily basis. Monthly, three-monthly, and six-monthly composites were analyzed for other radionuclides (e.g., radium 226, radium 228, cesium 137) (DOE 1972 - 1999).

Before the 1960s, there was no continuous monitoring of water flow through the storm sewer to Paddy=s Run Creek (Voilleque et al. 1995). Facility personnel periodically took grab samples downstream of the storm sewer lift station and analyzed them for total uranium. The facility has been monitoring effluent to Paddy=s Run Creek from 1966 to the present (DOE 1972 - 1999). Samples are analyzed for uranium and a variety of other radionuclides (Voilleque et al. 1995; DOE 1972 - 1999). These environmental data are reported in the annual Site Environmental Reports.

Judging that the waste streams flowed from each of the production buildings on site, contractors for CDC speculated that several uranium compounds were present in the liquid waste effluent discharges to the Great Miami River and Paddy=s Run Creek (Voilleque et al. 1995). The ratios of the various uranium compounds depended largely on the pH of the water. Based on the high volume of water released from the facility, many of the uranium compounds, even the relatively insoluble compounds (e.g., uranyl fluoride, UF4), would have been dissolved in the waste streams. Compounds containing uranium, such as the uranyl ion (UO2++), would probably predominate. There may have also been small particulates of the insoluble uranium compounds, triuranium octaoxide (U3O8) and uranium dioxide (UO2), among the suspended solids present in the liquid effluent releases from the facility (Voilleque et al. 1995).

Other radioactive contaminants released to surface water from the Fernald facility at various times over the years of operation included decay, fission, and activation products of uranium, thorium, and recycled uranium. For example, releases of thorium and its decay product (radium 228) occurred when thorium was processed at the site in the 1950s and from 1964 to 1988. The facility measured certain radionuclides in liquid effluents to the Great Miami River and Paddy=s Run Creek during various periods of operation. Beginning in 1976, the facility measured concentrations of plutonium, neptunium, radium, and some fission products (cesium 137, ruthenium 106, technetium 99, and strontium 90) in liquid effluents to the Great Miami River; however, the extent of these measurements varied over time (DOE 1972 - 1999).

There were also "unplanned" releases of contaminants to the Great Miami River and Paddy=s Run Creek from accidental spills, leaks, or discharges from the facility. Contractors for CDC estimated concentrations of uranium and other radionuclides in these "unplanned" releases using information contained in incident reports and other written correspondence about incidents at the Fernald facility from 1954 to 1989 (Voilleque et al. 1995). The release points for unplanned releases to surface water are the same as for "routine" releases; that is, through Manhole 175 to the Great Miami River or to Paddy=s Run Creek.

Estimated Exposure Doses

ATSDR scientists evaluated past, current, and potential future exposure to chemicals in surface water off site of the Fernald facility. Uranium is the only chemical evaluated for this pathway.

ATSDR scientists also evaluated current and potential future exposure to radioactive contaminants in surface water off site of the Fernald facility. Uranium and thorium are the primary radioactive contaminants, and strontium 90; technetium 99; cesium 137; radium 226 and 228; neptunium 237; and plutonium 238 and 239 are the secondary radioactive contaminants evaluated for this pathway. Collectively, we refer to all radionuclides evaluated for this pathway as "radioactive contaminants."

Past exposures to radioactive contaminants in surface water were addressed in the Fernald Dosimetry Reconstruction Project and Fernald Risk Assessment Project (Voilleque et al. 1995; Shleien et al. 1995; Killough et al. 1998a, 1998b; CDC 1998, 1999). A description of these projects, conducted by and for CDC, is provided in Appendix D of this report.

Exposure to contaminants while wading or playing in Paddy=s Run Creek or the Great Miami River may occur via incidental ingestion and direct contact with the skin (dermal contact). ATSDR scientists assumed that ingestion of surface water was the only route of exposure (and exposure medium) for chemicals in Paddy=s Run Creek and the Great Miami River. We made this assumption because uptake into the body (absorption) through the skin is minimal for uranium (ATSDR 1999b) and it is unlikely that children will accidentally ingest sediments while wading and playing in the creek and river (Killough et al. 1998b).

ATSDR scientists assumed that exposure to radioactive contaminants in Paddy=s Run Creek and the Great Miami River may occur via ingestion of surface water, and via external exposure to radioactive contaminants in surface water in the creek and river. Children residing near the Fernald site are most likely to play or wade in Paddy=s Run Creek in the spring, when it is a flowing stream. Older children and adults may periodically play, wade, or fish in the Great Miami River. These activities probably occur only sporadically, because the river is turbulent and rapidly flowing.

   

Estimating Exposure Dose

   
    

ATSDR scientists evaluated two hypothetical exposure scenarios for exposure to chemical and radioactive contaminants in surface water pathways: (1) a young child who plays in Paddy's Run Creek near the site and incidentally ingests contaminated surface water, and (2) an older child who plays in the Great Miami River near the site and incidentally ingests contaminated surface water.

   

In estimating chemical and radiological doses, ATSDR evaluated two hypothetical exposure scenarios. The first scenario assumes exposure to a young child, 2 to 5 years old, weighing 13 kg, who incidentally ingests one-quarter of a liter of contaminated water while playing in Paddy=s Run Creek every day, 6 months of the year (EPA 1999).

The second hypothetical exposure scenario assumes exposure to an older child, 6 to 11 years old, weighing 20 kg, who incidentally ingests one-quarter of a liter of contaminated water while playing in the Great Miami River every day, 6 months a year (EPA 1999).

We assumed exposure to a child because children, with their immature or developing systems, may have increased sensitivity to the toxic effects of uranium. ATSDR does not have direct evidence that shows whether children play or have played in Paddy=s Run Creek or the Great Miami River. However, 1990 Census data for Butler and Hamilton Counties indicate that 922 persons live within 1 mile of the Fernald facility. Of these, an estimated 110 persons are 6 years old or younger (as discussed in the "Background" section of this report under " Demographics"). The closest residence is located directly southeast of the site and off-site contaminated areas in Paddy=s Run Creek and the Great Miami River are not restricted. Therefore, ATSDR scientists made conservative assumptions to estimate exposure dose from chemical and radioactive contaminants in surface water pathways.

Chemicals

ATSDR scientists calculated two types of chemical exposure doses for exposure to uranium in surface water for the two hypothetical exposure scenarios (described above). These are a body dose and a dose to the kidney.

The kidney is the target organ for chemical effects of uranium ingestion. The chemical effects of uranium result only after the uranium is absorbed from the gastrointestinal tract into the bloodstream and transported (distributed) to the kidney. In estimating dose to the kidney, ATSDR scientists assumed that 5% of the uranium in ingested surface water is absorbed into the blood. This is a conservative assumption, because data from human ingestion studies and pharmacokinetic models indicate that the maximum absorption of uranium from the gastrointestinal tract (e.g., stomach, small intestine) ranges from 2% to 4% for the most soluble forms of uranium (ATSDR 1999b; ICRP 1995a).

The gastrointestinal absorption of uranium does not vary substantially by age (ATSDR 1999b; ICRP 1995a). Recent information suggests that children 5 years old and older have rates of gastrointestinal absorption for uranium that are similar to those of adults (ICRP 1995a). Gastrointestinal absorption rates are not known for children younger than 5. Because there is no indication that uranium soil absorption rates for children are higher than for adults, ATSDR scientists assumed the absorption rate for a small child (2 to 5 years) is equal to that for an older child (6 to 11 years), and that rates for children under 12 years (for both exposure scenarios) are similar to the maximum absorption rate for adults (or 5%). In estimating dose to the kidney, we assumed that 12% of the absorbed uranium dose is distributed to the kidney (ICRP 1979, 1995a; Zhao and Zhao 1990).

   

Health-Based Guidelines for Chemical Uranium

   
    

There are two types of health guidelines for ingested chemical uranium. These are: (1) a body dose, presented as milligrams of uranium per kilogram of body weight per day (mg/kg/day), and (2) a dose to the kidney, presented as micrograms of uranium per gram of kidney (µg/g).

   

We then compared our estimated chemical exposure doses for ingestion of uranium in surface water to the health-based guidelines to determine whether further evaluation of public health hazard was warranted. Additional information about the health-based guidelines for uranium is presented in the "Public Health Implications" section of this report.

Radiation

ATSDR scientists calculated three different types of exposure doses for radioactive contaminants in surface water. These are a committed effective dose (whole body), an equivalent dose (bone surface), and an external dose to the whole body. The bone surface is the major target organ for radiation effects from ingested uranium and most of the other radioactive contaminants in surface water.

Past Exposure

Contractors for the CDC estimated past concentrations of uranium and other radionuclides in Paddy=s Run Creek and the Great Miami River at downstream locations where humans are likely to be exposed while wading, playing, or swimming. The estimates were based on measurements of contaminant concentrations at the points of discharge into Paddy=s Run Creek and the Great Miami River, information about additional "unplanned" releases of materials to these surface waters, and simple dilution models (Killough et al. 1998a). The dilution models were used to account for the dilution and transport of contaminants in the receiving body of water (Paddy=s Run Creek or the Great Miami River) at a potential point of exposure downstream of the discharge point. Their estimated maximum exposure concentrations are presented in Table 13 (below).

Table 13. Estimated maximum past uranium concentrations at potential exposure points in surface water off site of the Fernald facility

 Potential Exposure Point

Estimated Maximum Uranium Concentration (mg/L)

Year of Maximum Concentration

Paddy=s Run Creek

529

1964

Great Miami River

17

1960 and 1964

Key mg/L = micrograms of uranium per liter of water Source: CDC 1998

 

We used these estimated concentrations to calculate past chemical exposure doses for surface water pathways. Our estimated doses for both hypothetical exposure scenarios are presented in Table 14 (below).

 

Table 14. Estimated maximum past uranium (chemical) exposure doses for hypothetical exposure scenarios for surface water pathways

 Exposure Point

Estimated Maximum Uranium Concentration
(mg/L)

Estimated Body Dose*
(mg/kg/day)

Estimated Kidney Dose* (mg/g)

Scenario #1: Younger child playing in Paddy=s Run Creek

529

0.005

0.002

Scenario #2: Older child playing in the Great Miami River

17

0.0001

0.00005

Key
mg/L = micrograms of uranium per liter water
mg/kg/day = milligrams of uranium per kilogram of body weight per day
mg/g = micrograms of uranium per gram of kidney

* Equations used to estimate doses for this pathway are described in Appendix BCExposure Doses and Health-Based Guidelines.

 

Our estimated exposure doses for scenario #1, past exposure to a small child via incidental ingestion of surface water in Paddy=s Run Creek, slightly exceeds the health-based guideline for ingested chemical uranium. Our estimated exposure dose for scenario #2, past exposure to an older child via incidental ingestion while playing in the Great Miami River, is lower than the guideline value by a factor of 20. Our estimated kidney doses for both scenarios are 50 to 2,000 times lower than the proposed lower-bound threshold for kidney toxicity (Morris and Meinhold 1995).

ATSDR scientists evaluated the public health hazard for this pathway together with other exposure pathways (i.e., groundwater, soil, air, and biota) that contribute to total uranium exposure to Fernald residents. This evaluation is presented in the "Public Health Implications" section of this report.

The effects from past exposure to the radioactive contaminants in off-site surface water have been addressed in the Fernald Dosimetry Reconstruction Project and the Fernald Risk Assessment Project (Voilleque et al. 1995; Shleien et al. 1995; Killough et al. 1998a, 1998b; CDC 1998, 1999). A brief description of these projects conducted by and for CDC is presented in Appendix D of this report.

Current Exposure

The Fernald facility routinely measures concentrations of uranium and other radionuclides in the Great Miami River and Paddy=s Run Creek. These environmental sampling data are reported in the annual Site Environmental Reports (DOE 1972 - 1999). Maximum current uranium concentrations at potential exposure points in Paddy=s Run Creek and the Great Miami River are presented in Table 15 (below).

Table 15. Current uranium concentrations at potential exposure points in surface water off site of the Fernald facility

 Exposure Point

Uranium Concentration (mg/L)

Year the Concentration Was Detected in Surface Water

Paddy=s Run Creek downstream of site (sample location W7)

53

1990

Great Miami River Effluent (Manhole 175)

902*

1989

Great Miami River downstream of site (sample location W4, Miamitown)

4.8

1995

Key
mg/L = micrograms of uranium per liter water
* The uranium concentration at Manhole 175 represents the highest annual average concentration; uranium concentrations at Paddy=s Run Creek (sample location W7) and the Great Miami River (sample location W4) represent annual maximum concentrations.

Source: DOE 1972B1999

ATSDR scientists used these measurements to estimate current chemical exposure doses for the two hypothetical exposure scenarios for surface water pathways. For exposure scenario #2, incidental ingestion of water in the Great Miami River by an older child, we used the maximum uranium concentration detected in the Great Miami River downstream of the discharge point to the river, to estimate exposure doses. We assumed that this concentration represents uranium concentrations in the river, considering dilution in river water before reaching a point where human exposure is likely to occur. Our estimated chemical exposure doses for both hypothetical exposure scenarios are presented in Table 16 (below).

Table 16. Estimated current uranium (chemical) exposure doses for hypothetical exposure scenarios for surface water pathways

 Exposure Point

Estimated Uranium Concentration
(in mg/L)

Estimated Body Dose*
(mg/kg/day)

Estimated Kidney Dose* (mg/g)

Scenario #1: Younger child playing in Paddy=s Run Creek

53

0.0005

0.0002

Scenario #2: Older child playing in the Great Miami River

4.8

0.00003

0.00002

Key
mg/L = micrograms of uranium per liter water
mg/kg/day = milligrams of uranium per kilogram of body weight per day
mg/g = micrograms of uranium per gram of kidney

* Equations used to estimate doses for this pathway are described in Appendix BCExposure Doses and Health-Based Guidelines.

Our estimated exposure doses for scenarios #1 and #2, under current conditions, are lower than the health-based guidelines for ingestion of uranium. Our estimated kidney doses for these scenarios are also considerably lower than the proposed lower-bound threshold for kidney toxicity (Morris and Meinhold 1995).

Despite the fact that our estimated doses are lower than health-based guidelines for ingested uranium, ATSDR scientists evaluated the public health hazard for this pathway together with other exposure pathways (i.e., groundwater, soil, air, and biota) that contribute to total uranium exposure to Fernald residents. This evaluation is presented in the "Public Health Implications" section of this report.

Annual maximum concentrations of radioactive contaminants in surface water at potential off-site exposure points in Paddy=s Run Creek and the Great Miami River are presented in Table 17 (below).

Table 17. Maximum concentrations of radioactive contaminants, by year, at potential exposure points in surface water off site of the Fernald facility

 Exposure Point

Radionuclide

Concentration in pCi/L (Bq/L)

Year of Maximum Concentration

Great Miami River effluent (Manhole 175, Discharge 001)

Strontium 90 Technetium99
Ruthenium 106
Cesium 137
Lead 210
Radium 226
Radium 228
Actinium 227
Thorium 228
Thorium 230
Thorium 232
Thorium 234
Uranium 234
Uranium 235
Uranium 236
Uranium 238
Neptunium 237
Plutonium 238
Plutonium 239/240
0.40 (0.01)
< 1,690 (62.6)
< 90 (3.33)
< 11 (0.41)
< 8.5 (0.31)
< 4.9 (0.18)
< 10.6 (0.39)
< 1.0 (0.04)
< 0.3 (0.01)
0.7 (0.03)
< 0.5 (0.02)
267 (9.89)
185.4 (6.87)
11.1 (0.41)
7.0 (0.26)
267 (9.89)
< 0.21 (0.01)
< 0.10 (0.00)
< 0.13 (0.00)

1990

Great Miami River downstream of effluent (sample location W4)

Strontium 90
Radium 226
Radium 228
Total uranium
1.2 (0.04)
0.29 (0.01)
5.2 (0.19)
3.2 (0.12)

1995

Paddy=s Run Creek downstream of site (sample location W7)

Paddy=s Run Creek downstream of site (sample location W7)

0.07 (0.00)
6.00 (0.22)
13.5 (0.5)

1995

Key
pCi/L = picocuries per liter
Bq/L = becquerels per liter

ATSDR scientists used these concentrations to estimate current radiation exposure doses for the two hypothetical scenarios for surface water pathways. Table 18 (below) presents ATSDR=s estimated committed effective doses (whole body) and committed equivalent doses (bone surface) from ingestion of the water, and external doses from being covered with water (submersion) for radioactive contaminants in surface water in Paddy=s Run Creek and the Great Miami River.

Table 18. Estimated exposure doses for radioactive contaminants in surface water for the hypothetical exposure scenarios

 Exposure Point

Year of Maximum Concentration

Estimated Committed Effective Dose (whole body) for 1-Year Intake, Maximum Concentration, in mrem (mSv)*

Estimated Equivalent Dose (bone surface) for 1-Year Intake, Maximum Concentration, in mrem (mSv)*

Estimated External Dose (skin) for 1-Year Exposure, Maximum Concentration, in mrem (mSv)H

Scenario #1: Younger child playing in Paddy=s Run Creek

1995

5.23 (0.052)

176.6 (1.766)

3.1E-06 (3.1E-08)

Scenario #2: Older child playing in the Great Miami River

1995

3.7 (0.037)

161.6 (1.616)

7.3E-06 (7.3E-08)

Key
mrem = millirem
smSv = millisieverts

* Used ICRP 67 and ICRP 72 Methodology and Conversion Factors .
H
Used EPA=s Federal Guidance Report No. 12 for Conversion Factors.

The external exposure to the skin is insignificant and will not be evaluated further. Further evaluation of other human exposures to radioactive contaminants in surface water, and other pathways that contribute to radiological doses at the site (i.e., groundwater, soil, air, biota) is discussed in the "Public Health Implications" section of this report. Included in this discussion is a determination of whether these estimated doses represent an increased likelihood of developing fatal cancers or bone cancer during a person=s lifetime.

Potential Future Exposure

Remediation activities at the Fernald site are expected to continue for several years. During that time, former production buildings will be destroyed and contaminated soils around and under these buildings will be removed from the area and transported to an off-site disposal area. This should minimize releases to surface waters and the potential for human exposure to chemicals and radioactive contaminants in the Great Miami River and Paddy=s Run Creek. According to available environmental data, there is no indication that future activities will result in human exposure to contaminated surface water off site of the Fernald facility. However, if additional information becomes available indicating that contaminants have been released or migrated to surface water off site, the surface water exposure pathways should be re-evaluated.

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