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PUBLIC HEALTH ASSESSMENT

US DOE MOUND FACILITY
[a/k/a MOUND PLANT (USDOE)]
MIAMISBURG, MONTGOMERY COUNTY, OHIO


APPENDIX A: HISTORIC RELEASES OF NONRADIOACTIVE SUBSTANCES TO WATER AND AIR

Background

In this appendix we review data describing releases of nonradioactive substances from the Moundfacility to the environment. The Mound environmental monitoring reports are the primary source ofthe data. This Appendix is intended to supplement information presented in the EnvironmentalContamination and Evaluation section in the main body of this public health assessment. Thisdiscussion is divided into considerations of nonradioactive substances in water and nonradioactivesubstances in air.

Exposures to Nonradioactive Substances in Water

ATSDR scientists reviewed Department of Energy (DOE) data (1971-1995) in the Moundenvironmental monitoring reports for nonradioactive liquid effluents to the Great Miami River andthe Miami-Erie Canal. Mound employees did not routinely sample the river itself for nonradioactivesubstances because there have always been many other contributors of nonradioactive substances tothe river upstream from Mound. Initially, the effluent data represented analyses of a compositesample from each of Mound's liquid effluent streams. After 1974, the effluent streams to the GreatMiami River and the Miami-Erie Canal were analyzed separately.

From 1971 to 1975, Mound employees compared levels of nonradioactive substances in liquideffluents to Environmental Protection Agency (EPA) Surface Water Criteria for Public WaterSupplies. In July 1975, the Mound Laboratory received an EPA National Pollutant DischargeElimination System (NPDES) permit, which specifies how effluent streams will be sampled andwhat criteria they must meet. The sampling criteria under the Mound permits were substantiallyrevised in 1981. The State of Ohio became the administrator of the permits when they wererenewed and modified in 1985. The permits were renewed with modifications in 1992, andmodified again in 1994. The data collected under the effluent regulatory system and published inthe Mound annual environmental reports are the subject of this portion of our review.

Over the 25-year period (1971-1995), there have been numerous instances where the standards forthe effluent streams set by the NPDES permits (or their predecessors) were exceeded; however, therehave been far fewer such instances since 1985, when the Ohio EPA ordered Mound officials to takecorrective actions to control the release of suspended solids. ATSDR scientists consider thestandards outlined in the NPDES permits to be protective of the public's health. Many of therecorded instances where effluent streams exceeded test standards during the 25 years have beenrelated to releases from the sanitary (sewage) treatment facility. Effluent tests that indicateperformance of the sanitary (sewage) treatment facility include suspended solids, chlorine, fecalcoliform, and biochemical oxygen demand. Reasons given in the reports for exceeding permitstandards include equipment problems, high rains or melting snow, and salting roads to removesnow and ice. Rain, snow, and salt affect the surface runoff and change the quality of the effluentstreams. There were also occasional instances where oil and grease exceeded standards in the earlieryears and other times when copper, iron, and nickel exceeded standards. There was one instance(1989) where 1,1,1-trichloroethane was slightly above standards. In nearly all of these cases,deviations from the standards were small.

ATSDR scientists are not concerned that any of these data represent a public health hazard exceptthe fecal coliform bacteria test results in the early 1980s. During a period from 1981 through 1986,there were one or more instances each year where fecal coliform bacteria exceeded the standard. In1982, 1983, and 1984, the levels were 12, 8, and 12 times the standard, respectively. (The standardwas 2,000 MPN per 100 mL [milliliters], maximum reading, where MPN stands for "most probablenumber" and is a way of counting bacteria colonies in the laboratory.) We are concerned thatpeople swimming and boating in the Great Miami River at the recreational facility at theChautauqua Dam might have been exposed to pathogenic microbiological organisms because offecal pollution from the Mound facility.

The 1982, 1983, and 1984 fecal coliform maximum readings were the only three that were at levelsof concern among the 6 years when the standards were exceeded. In 1984, the high fecal coliformreading occurred in January. Since we do not know of anyone who was swimming in the river inJanuary, we do not believe there was any public health hazard associated with this release. In 1982and 1983, however, the high readings occurred in August. The effluents released from the Moundsite on these sampling dates did pose a health hazard to people engaged in recreational activitiesdownstream in the Great Miami River. The most common health effects from exposure to thesereleases, if any, would have been gastroenteritis, Giardiasis, Salmonellosis, and Shigellosis [1, 2]. These releases are not persistent contaminants in the environment, and they would not pose a long-term public health problem.

Conditions in the Great Miami River may not have been conducive to the survival ofmicroorganisms on the days that high levels of fecal coliform were present in Mound's liquideffluents. The river may have been chemically or physically toxic to microorganisms. On the otherhand, we have taken into account dilution in the river, and we consider that the temperature of thewater in August was likely conducive to the multiplication of bacteria and other microorganisms. We don't know what the actual conditions were, so we consider the releases a health hazard.

In addition to the data we've just described (NPDES data), ATSDR scientists considered whathistorical water release information we are missing.

In the 1950s, nonradioactive liquid releases to the Great Miami River included strong inorganicacids, citric acid, formic acid, detergents, soaps, chelating agents, lubricating oils, organic solvents,sodium hydroxide, sodium tartrate, formaldehyde, and many other substances [3]. These chemicalswere released to the waste stream that flowed off site to the river without restriction [3]. There is noindication that liquid chemical wastes were ever released to the Miami-Erie Canal.

We do not know the quantities of nonradioactive substances released to the river, or those already inthe river, during this time period. Therefore, we are not able to estimate doses to people who swam,boated, or engaged in other recreational activities in the Great Miami River before 1971, andingested or breathed nonradioactive substances from the river, or got water on their skin or ate fishfrom the river.

In summary, there were two instances in the early 1980s when the Mound facility released to theenvironment liquid effluent containing nonradioactive contaminants that posed a public healthhazard. The contaminants are pathogenic microorganisms. There are no other documented releasesof nonradioactive substances from Mound at levels that posed a public health hazard; however, wedo not know how much chemical pollution Mound Laboratory employees released to the GreatMiami River in the 1950s.

Exposures to Nonradioactive Substances in Air

Mound scientists began reporting particulate matter concentrations on and off site in 1971 [4]. Thestandard was 60 micrograms per cubic meter (µg/m3), annual geometric mean, from 1972 through1993. The National and the Ohio Ambient Air Quality Standards for particulate matter werechanged (made more stringent) to 50 µg/m3, annual arithmetic mean, in 1994. In the 1970s and theearly 1980s, air particulate matter concentrations regularly exceeded the Ohio Ambient Air QualityStandard both on site and off site at the Mound facility. Since 1989, all the Mound air particulatematter concentration measurements have met the standards. However, the U.S. EPA is currentlyimplementing further changes to the air particulate matter standards (making them more stringentagain) to reflect newer information about the toxic effects from breathing particulate matter. Therefore, air particulate matter concentrations that met ambient air quality standards historicallywould not necessarily meet the newly proposed ambient air quality standards.

Many particulates do not exhibit a specific toxic effect but may still inhibit the clearancemechanisms in the lungs or, at relatively low concentrations, cause sensitization or allergic reactionsin sensitive individuals. The Ambient Air Quality Standards for particulate matter were establishedto protect the public from excessive, respirable, solid material in air. The standard specifies a massconcentration in air and not the chemical identity of the solid material. The standard today appliesto particulate matter that has an aerodynamic diameter of 10 micrometers or less [5]. This size ofparticulates describes "respirable" particles. Larger particles are exhaled or swallowed during thenormal breathing process and do not cause health problems. Mound's data is derived by weighingfilter papers from the air monitors before and after pulling air through them. This method(gravimetric) results in a total particulate mass that may include particles larger than 10micrometers; to the extent that it does, the data overstate the health hazard. Since we don't knowwhat portion of the data represent respirable particulates, we don't know whether the air quality wasever a problem. To the extent that air particulate matter under 10 micrometers exceeded thestandard, more people could have experienced allergic reactions and difficulties breathing.

Mound's environmental reports state that the particulate matter measurements are a measure of theambient air quality in the area and that emissions from the site add a "negligible contribution" to theambient air. This may be true. The Mound facility did not exceed emissions standards during theyears that particulate concentrations at air monitors exceeded ambient air quality standards. Nevertheless, we have very little data for nonradioactive substances in air before 1976 and nonebefore 1971.

ATSDR scientists reviewed information pertaining to the sources of nonradioactive airborne emissions from Mound. Since 1971--and possibly much earlier than that, although we don't know how early--the primary source of nonradioactive emissions to the air from the Mound facility has been the site steam power plant. The power plant operates on natural gas except in very cold weather, when it is converted to No. 2 fuel oil. Mound scientists began reporting emissions of particulates and sulfur dioxide from the power plant, organic compounds from the paint shop, and particulates from the explosives disposal and fire-fighting training areas in 1976. Other sources for nonradioactive air emissions mentioned in other environmental reports include maintenance grinding operations, carpentry shop operations, and construction and deconstruction activities on site. In 1994, Mound staff stopped reporting air emissions by on-site operations and simply reported air emissions as total suspended particulates, sulfur oxides, nitrogen oxides, volatile organic compounds, carbon monoxide, and lead.

Mound employees burned solid and liquid wastes in Area B from 1948 to 1969 [6]. The MoundPlant RI/FS (Remedial Investigation/Feasibility Study) Site-Wide Work Plan contains the followingdescription of these materials: "administrative and laboratory trash including paper, glass, wood,plastics, kitchen garbage, ...bottled urine samples ...[and] perhaps ...beryllium, mercury,trichloroethene, carbon tetrachloride, nickel carbaryl, benzene, alcohol, photo processing solutions,and plating materials..." [6]. The State of Ohio enacted a law banning non-permitted, open burningin 1969, and the practice was discontinued. Since it was legal, we expect that open burning was awide-spread practice on both public and private properties throughout the period before it wasbanned. We are not able to estimate the inhalation exposures to air emissions from these activities atthe Mound Laboratory because we do not know the quantities of the emissions. We note, however,that burning wastes containing metals (beryllium, mercury, and nickel) can result in very toxicairborne particulate matter [7].

In summary, the available data for nonradioactive air emissions from Mound (1976-1995) do notindicate that the emissions were at levels that would cause adverse health effects. The reported airparticulate matter concentrations, both on and off site, have not exceeded EPA and Ohio AmbientAir Quality Standards since at least 1989. However, we don't know whether the air (since 1989)would meet the new ambient air quality standards for particulate matter. Finally, there are noMound data describing nonradioactive air quality before 1971, including 21 years when Mound Laboratory personnel disposed of solid and liquid wastes by open burning.

References

  1. Brock TD, Brock KM, Ward DM. Basic microbiology with applications, third edition.Prentice-Hall, Englewood Cliffs, New Jersey, 1986.

  2. Centers for Disease Control. Water-related disease outbreaks, surveillance, annual summary 1982, and annual summary 1983, (reports) issued 1983 Aug and 1984 Sep, respectively.

  3. US Department of Energy, Albuquerque Operations Office, Environmental RestorationProgram. Operable Unit 9, site scoping report volume 7- waste management report, MoundPlant, Miamisburg, Ohio. Draft Revision 0;1991 Nov.

  4. Carfagno DG, Westendorf WH. Environmental monitoring report: July - December 1971and 1971 summary. Mound Laboratory, Monsanto Research Corporation, US AtomicEnergy Commission. MLM-1922; 1972 May 22.

  5. Environmental Protection Agency. National primary and secondary ambient air quality standards for particulate matter, Code of Federal Regulations, 40 CFR 50.6, 1987 Jul 1.

  6. US Department of Energy, Albuquerque Field Office, Environmental Restoration Program. Remedial investigation/feasibility study, Operable Unit 9, site-wide work plan, field sampling plan, Mound Plant, Miamisburg, Ohio. Volume I, work plan text (sections 1-15). Final;1992 May.

  7. Goyer RA. Toxic effects of metals. (In) Casarett & Doull's toxicology, the basic science of poisons, fifth edition, Klaassen CD (editor). McGraw-Hill, New York. 1996:691-736.

APPENDIX B: POLONIUM-210 RELEASES FROM THE MOUND LABORATORY

Polonium-210 in Air

The Monsanto Chemical Company brought polonium-210 research to the Mound Laboratory fromthe Dayton Project when the Miamisburg plant opened in 1948; work with radioactive materials("hot-side" operations) began in 1949. From the beginning, Mound Laboratory scientistsestablished an aggressive environmental monitoring program. However, we do not have all theenvironmental data today that they originally collected, and the quality of the data is not as high asthe quality of environmental data generated today.

We have polonium air summary data for most months (1949 through March 1954), quarters (April1954 through 1962), half-years (1963 into the early 1970s), and years (1972 through 1974). Mound Laboratory scientists stopped reporting concentrations of polonium-210 in the environmentin 1975. They had stopped using it several years before and environmental levels had decreased,through radioactive decay, to three orders of magnitude below the Radioactivity ConcentrationGuide value recommended by the United States Energy Research and Development Administration,the immediate predecessor to DOE, at that time.

Although a few of the earlier reports are missing or are illegible, the air data we have are consistent. In many of the air samples, Mound Laboratory personnel detected no polonium. Among thesamples where they did detect polonium, the maximum levels from different reporting periods anddifferent locations range from 2.7 x 10-13 microcuries per milliliter (µCi/mL) to 6.56 x 10-11µCi/mL. The highest level detected (6.56 x 10 -11 µCi/mL) is more than three times as high as thenext highest level in the set of environmental reports we have.

The usefulness of the available data--especially data from the 1950s--is limited. Air samples collected before 1972 were not collected in one location around the clock as the air samples Mound scientists collect today at their permanent air monitoring stations. Therefore, we cannot be sure that the polonium-210 air data reported before 1972 reflect maximum, or even average, concentrations of polonium-210 that people might have breathed at these locations.

Nevertheless, ATSDR staff asked, do the available data show that there was a problem? Weconsidered whether a person who breathed air containing the highest concentration of polonium-210that we have data for would have experienced any adverse health effects. A 1958 quarterly healthphysics report indicates polonium-210 was measured at 6.56 x 10-11 microcuries per cubiccentimeter (µCi/cc) in air at Fairhaven, Ohio; (this is equivalent to 6.56 x 10-11 µCi/mL) [1]. Thiswas the maximum reading recorded during the third quarter of 1958 and the highest measurementwe located in any of the environmental reports.

We note that the data do not permit us to estimate with any certainty what concentrations of polonium-210 people actually were exposed to. During the same quarter in which the highest polonium concentration in air was recorded, a second sample was collected at the same location one month later; the polonium-210 concentration in the second sample was 2 orders of magnitude lower than the first. If we simply average the two numbers, the resulting dose is half the higher number. But we don't know what the real long-term exposures were. It is very likely that exposures to polonium in air from the Mound Laboratory over the quarter, on average, were much lower than the highest reading because of non-continuous operations at the plant and variable wind patterns. On the other hand, we may not have measurements of higher concentrations in air that resulted in higher exposures--at this location or elsewhere.

When we consider the reported air concentrations, we must also acknowledge that there isuncertainty as to the minimum dose of polonium-210 necessary to cause adverse health effects. Thisis because polonium-210 is naturally occurring and is found throughout the human body. Thismakes it difficult to assign the cause of an adverse health outcome to exposures to environmentalpolonium. The human body normally incorporates polonium-210 from air, water, food, andespecially tobacco smoke, and a person's body content of polonium will vary with diet and smokinghabits [2]. We know from human studies where polonium-210 accumulates in the body once it is inthe bloodstream, but our toxicity information comes from studies of mice and rats subjected to highdoses of polonium-210, not from human evaluations.

Studies of uranium miners have shown that polonium-210 is distributed throughout many bodytissues, but it tends to concentrate in the testes and kidney cortex. However, the distribution ofpolonium-210 in miners may result from primary exposure to and distribution of radioactive lead,which decays to polonium-210, and not primarily from the distribution of polonium-210 [3]. Otherstudies show that when ingested, polonium-210 aggregates in the gut wall but eventually appearspredominantly in the red blood cells, sperm, and seminal fluid. Researchers studied the effects ofpolonium-210 on reproduction in mice; depletion of spermatocytes occurred at doses greater than0.01 µCi per kilogram of body weight (0.01 µCi/kg) [4]. Bone cancers and lymphomas in miceoccurred at higher doses (0.46 µCi/kg and 0.9 µCi/kg, respectively), and sarcomas, carcinomas ofsoft tissue, liver damage, and malignant renal tumors occurred in rats at even higher doses (6µCi/kg) [4].

We used the results from the mice studies to evaluate polonium-210 exposures in humans. Thelowest observed adverse effect level of polonium-210 that has been shown (in mice) to cause healthproblems is 0.01 µCi per kilogram of body weight [4]. A 30-kg child would have to breathe thehighest-polonium air concentration (6.56 x 10-11 µCi/mL) continuously for around 300 days beforereceiving this much polonium radioactivity, and an adult male would have to breathe the air formore than a year before receiving this much radioactivity. Based on this information, we do notbelieve that people would have experienced adverse health effects from air exposures to polonium-210 released from the Mound Laboratory. However, based on the shortcomings of the air datacollected before 1972, the data gaps before 1960, and the relative magnitude of polonium-210operations and releases during the 1950s, we cannot conclude that there were no exposures at levelsof health concern, either. Therefore, this exposure pathway is indeterminate.

Polonium-210 in Water

Mound Laboratory personnel monitored several locations in the Great Miami River for polonium-210 from very early in the plant's history. Nevertheless, as with air data, we have only limited datafrom the 1950s describing releases of liquid wastes containing polonium-210 and concentrations ofpolonium-210 in the Great Miami River. Reports before September 1951 indicate the number ofsamples that were collected from the river, but they do not provide the results of the sample analyses.

In the OU9 Site Scoping Report, Volume 7 - Waste Management document, Mound Plant staffreported liquid effluent radioactivities and waste sludge radioactivities (and liquid volumes of each)generated by the polonium-210 program [5]. These data cover September 1952 and October andNovember 1953 only; they show the highest levels of polonium-210 released to the Great MiamiRiver among all the data available.

The highest river concentration of polonium-210 for which we have data (7.4 x 10-5 µCi/mL) wasrecorded on August 22, 1955, at the location where the effluents enter the Great Miami River.

To evaluate these data, we estimated the dose for a person who swam in the river at the ChautauquaDam recreation facility and swallowed 100 milliliters of river water. (We know that it is unlikelythat people would swim in the Great Miami River in October or November, but we are evaluatingthe data as though the same releases or measured concentrations could have occurred at any time.)

We chose the Chautauqua Dam area of the river because a recreational facility that includes aswimming beach is there. We estimated the concentration of polonium-210 in the river at theChautauqua Dam for the polonium-210 release data by first calculating the average concentration ofpolonium-210 released to the river in each of the three months, and then reducing theseconcentrations by an amount that would be expected from dilution in the river. For the riverconcentration data, we took the highest level of polonium-210 measured in the river (at the effluentoutfall) and diluted it to a concentration we would expect at the Chautauqua Dam.

We estimated a dilution factor in the river by averaging the concentrations of polonium-210measured at the Chautauqua Dam during the period from the middle of 1960 through the end of1969. We compared this average to the average polonium-210 concentration measured in MoundLaboratory liquid effluents during the same period. The ratio of the two averages, 0.017, is anapproximate dilution factor.

Although the effluent data are presented as polonium radioactivities in waste water and in sludgeseparately, we assumed people would be exposed to polonium-210 from both waste water andsludge effluents. We don't actually know how the sludge behaved in the river- whether it enteredthe river continuously, whether the polonium in sludge would dissolve or become suspended in theriver water, and whether it would travel downstream at the same rate as the polonium released inwaste water. And we don't actually know the concentrations of polonium-210 in the effluentsreleased. Therefore, we assumed the total volumes and polonium radioactivities in both waste water and sludge were released continuously, together, throughout each month.

TABLE I. GREAT MIAMI RIVER CONCENTRATIONS AND DOSES FROM POLONIUM-210 IN MOUND LABORATORY EFFLUENT.

Month Polonium-210 concentration in water + sludge, in effluent (µCi/mL).* Polonium-210 concentration in water, at Chautauqua Dam (µCi/mL).** Polonium-210 radioactivity ingested in 100 mL river water (µCi). Radiation dose to an adult from ingesting 100 mL river water (mrem).
SEP 1952 8.96E-04 1.52E-05 0.0015 2.90
OCT 1953 4.29E-04 7.29E-06 0.0007 1.39
NOV 1953 3.10E-04 5.27E-06 0.0005 1.00
* Calculated from data in the Mound Plant OU9 Site Scoping Report, Waste Management Report [5]. ** Calculated as previous column times 0.017.

The maximum effluent concentrations of polonium-210 we calculated in waste water and sludgetogether are higher than the reported highest concentrations of polonium-210 measured in the GreatMiami River for these months. We have data for two of the three months; October 1953 river dataare illegible in the report. Reported maximum concentrations in the river at the effluent outfall are2.0 x 10-7 µCi/mL in September 1952 and 3.3 x 10-7 µCi/mL in November 1953. If we consideronly the water portion of the effluent data (not the sludge), the calculated concentrations ofpolonium-210 in effluent are still greater than the maximum measured concentrations at the outfall. The concentrations measured in the river and those we calculated from the effluent release data maybe different because the polonium-210 in sludge may not be dissolved in the river water, or the riverwas sampled at a time when the concentration of polonium-210 in the effluent was below averagefor the month, or there was some dilution by the river at the river sampling location.

The greatest amount of polonium-210 was released to the Great Miami River in September 1952,and the highest radiation doses would result from ingesting river water during this month (or anymonth with an equivalent release). Table I shows how much radioactivity and radiation dose aperson would receive from ingesting 100 mL of water. During September 1952, a personswallowing 100 mL of water would ingest 0.0015 µCi of polonium-210. For an infant (10 kg), thisquantity is more than 50 times smaller than our lowest observed adverse health effect level of 0.01µCi/kg; for an adult (70 kg), it is more than 450 times smaller. The radiation dose (2.90 millirems[mrem]) from this amount of radioactivity is also very small. This dose does not represent a healthhazard.

The available data show the maximum measured concentration of polonium-210 in the GreatMiami River is 7.4 x 10-5 µCi/mL. The diluted concentration of this quantity at the ChautauquaDam is about 1.2 x 10-6 µCi/mL. The dose would be about 0.23 mrem. This radiation dose is not ahealth hazard.

These calculations were meant to investigate whether people exposed at the most likely location inthe Great Miami River to polonium-210 released to the river would have experienced adverse healtheffects. Our results show they would not. However, we acknowledge that a person could haveswallowed more than 100 mL of contaminated water from the river, or the concentrations in theeffluents could have been higher than we calculated, or someone could have ingested water closer tothe effluent outfall where the concentrations were higher. (In our calculations, ingestion of 100 mLof effluent water at the outfall would have been a health hazard, but we don't think anyone woulddrink this water.) Regardless of our calculations, it is possible that more polonium-210 was releasedto the river than the available data indicate. We conclude, therefore, that although the data do notshow that polonium-210 released to the area waterways ever posed a public health hazard, the data are incomplete. Therefore, this pathway is indeterminate.

References

  1. Meyer HE. Quarterly health physics report through September 30, 1958. MoundLaboratory, Monsanto Chemical Company, Miamisburg, Ohio. 1958 Oct 23. (partial)

  2. Hunt VR. Polonium-210 measurements in human semen. Health Phys 1990 Apr;58(4):511-4.

  3. Blanchard RL, Moore JB. Body burden, distribution and internal dose of Pb-210 and Pa-210 in a uranium miner population. Health Phys 1971; 21:499-518.

  4. Thomas PA. Dosimetry of Po-210 in humans, caribou, and wolves in northern Canada. Health Phys 1994 Jun;66(6):678-90.

  5. US Department of Energy, Albuquerque Operations Office, Environmental RestorationProgram. Operable Unit 9, site scoping report volume 7- waste management report, MoundPlant, Miamisburg, Ohio. Draft Revision 0;1991 Nov.

APPENDIX C: HISTORIC RELEASES OF PLUTONIUM-238, HYDROGEN-3 (TRITIUM), AND OTHER RADIONUCLIDES TO THE ENVIRONMENT

Plutonium-238 and Hydrogen-3 (Tritium) in Air

Plutonium-238 was first incorporated in an RTG (radioisotopic thermonuclear generator) in 1961 atMound for use in the SNAP (Satellite Nuclear Auxiliary Power) program; however, research anddevelopment for this program began earlier [1, 2]. Studies of hydrogen-3 (tritium) began at theMound Laboratory in 1954 [1].

During the 1960s, the Mound Laboratory released the largest quantities of both plutonium-238 andtritium to the environment in the plant's history.

In 1960, the Mound Laboratory released more than 250 millicuries of plutonium-238 to theatmosphere [2]. This quantity is more than 16,000 times the quantity released to the air in 1994 [3]. In only one other year, 1967, did the air releases of plutonium-238 exceed even 20% of the quantityreleased in 1960. By 1972, total plutonium-238 air releases were about 0.1% of the quantityreleased in 1967, and they have been much lower than that in the years since 1972 [1, 2].

The earliest available data that describe air releases of tritium are for 1959 [1, 2]. Throughout the1960s, the Mound Laboratory released to the air tritium that exceeded 100,000 curies in every year;in 3 of those years, tritium releases exceeded 300,000 curies. The peak year for tritium air releaseswas 1967, when Mound operators released 364,685 curies [2]. By 1972, total tritium air releaseswere about 8% of the quantity released in 1967. With one minor exception, quantities of tritiumreleased to air have decreased since the early 1970s. In November 1989, there was an accidentalrelease of 38,268 curies of tritium to the atmosphere through the stack of the SW building [4].

We used a simple air transport and dispersion model, CAP88-PC, to evaluate the plutonium-238and tritium air releases [5, 6]. CAP88-PC (or the mainframe version, CAP88) is the computer codeused for assessing regulatory compliance with NESHAPs (the National Emission Standards forHazardous Air Pollutants). It incorporates a number of adjustable parameters, such as identity andquantity of radionuclides in air emissions, stack height, exit velocity, average meteorologicalconditions, and fraction of food products produced locally. The program calculates radiation dosesto people in the pathway of the stacks emissions. It computes effective doses for inhalation;ingestion of produce, leafy vegetables, milk, and meat; air submersion; and ground shine (radiationfrom radionuclides deposited on the ground surface). For tritium, CAP88 also computes dosecomponents from skin absorption and drinking water. CAP88 uses dose coefficients based on theICRP-26 and ICRP-30 dosimetry model; it uses a specific activity model for tritium dose estimates[7, 8, 9].

We obtained annual summaries of on-site meteorological data for 1989 through 1994 from MoundPlant senior scientists. We secured other information, such as stacks locations and heights,diameters, and exit velocities, and information about how Mound Plant scientists run their programfor NESHAPs compliance analyses from Mound's 1994 annual environmental monitoring report orfrom Mound senior scientists [3]. Using input from Mound's 1994 report, we were able toreproduce their results for 1994 to within a few percentage points. We then used the computermodel to calculate effective doses for air emissions of plutonium-238 and tritium for 1960, 1967,and 1989. We chose 1960 and 1967 because these were the years when plutonium-238 and tritiumreleases were highest, respectively. Also; 1967 was the year of the second-highest plutonium-238releases. We chose 1989 because it was the only recent year in which high releases of either radionuclide occurred.

TABLE I. ANNUAL EFFECTIVE DOSES DUE TO PLUTONIUM-238 AND HYDROGEN-3 (TRITIUM) AIR RELEASES FROM THE MOUND FACILITY, CALCULATED USINGCAP88-PC.

Year Releases Direction Distance Total Dose Percent of Dose
Pu-238 H-3 Pu-238 H-3
units curies curies NSEW meters millirems % %
1960 2.50 E-1 102,427 NE 825 - 1,150 19 55 45
1967 5.43 E-2 364,685 NE 975 36 6 94
1989 4.00 E-6 41,534 NNE 825 - 1,050 65 0.00 100

In Table I, direction and distance represents the direction and distance from the release point on thesite to the location with the highest dose estimate. The doses calculated are the total annual effectivedoses from exposures to plutonium-238 and tritium air releases. Percent of dose is the approximateportion of the total dose attributable to either plutonium-238 or tritium for that year's annualreleases.

In 1989, the total dose is higher than in the other years even though the total quantity of both plutonium-238 and hydrogen-3 released to the air in that year was lower than in the other years. For the years 1960 and 1967, we assumed the releases of radionuclides occurred at a constant rate throughout the year. For 1989, we know the accidental release of tritium in November of that year--accounting for 92% of the total tritium released for the year--occurred in one day. Because the dose a person gets depends on the concentrations of radionuclides in the air, and the concentrations depend upon the duration over which the radionuclides are released, a person directly in the pathway of the tritium release in 1989 would have breathed a sufficiently higher concentration of tritium to receive a larger radiation dose than someone in the pathway of the air releases in either of the other years. Nevertheless, this dose (65 mrem) is not a public health hazard. Based on these dose estimates and the evidence we present below, we have concluded that plutonium and tritium air releases from the Mound facility have never posed a health hazard.

We acknowledge that the CAP88 dispersion model does not account for unusual terrain, unusualweather, and inconsistencies in the dispersion of particulates from the Mound stacks. We don'tknow whether the releases during the year were frequent or consistent in magnitude. Also, weinserted the 1994 stacks configuration and meteorological conditions from the Mound Plant into themodel to represent conditions in 1960 and 1967; (we used 1989 meteorological data to model 1989doses). These assumptions may not be entirely valid, but we think these doses are useful as anestimate of the general magnitude of doses a person would receive from airborne releases for theseyears.

We also know that sources other than the stacks may have contributed to off-site air contamination. We expect that these types of releases (for example, resuspension of contaminated dirt duringexcavation on site) would be close to the ground and that particulates from these releases would nottravel as far as those from the stacks releases. For example, in 1994, the SM (Special Metallurgical)Building was torn down. The SM Building was near Mound Road across from the golf course andwas in the area where Mound employees conducted plutonium operations. We expect that somedust and dirt will be disturbed during the tearing down of buildings; we note that the highest level ofplutonium-238 recorded at an air monitoring station in 1994 occurred at the station nearest the SM Building [3].

Although we recognize that the CAP88 dispersion model may not provide us with precise doseestimates, we have additional evidence that the air releases of plutonium-238 and tritium never posed a health hazard.

  1. None of the air samples collected by Mound personnel during the 1960s show that these radionuclides in air were ever a health problem.
  2. Unlike the polonium air data, our data set of plutonium-238 and tritium releases to theenvironment and plutonium-238 and tritium air monitoring results is uninterrupted. Theplutonium-238 air sampling data before 1972 are limited in the way that we described forpolonium-210 air data (i.e., the air samples were not collected continuously; see AppendixB). Also, we do not have data for tritium releases to air from 1954 through 1958. Nevertheless, these data limitations do not appear to be significant. Tritium releases in 1959and 1960, for example, were considerably lower than tritium releases for the remainder ofthe 1960s. Mound environmental reports state tritium was not detected at monitoring sitesbefore 1967. This information suggests we have air measurements during the years whenplutonium-238 and tritium concentrations were highest in air, and none of the data indicate these radionuclides were ever at levels of health concern.

  3. The soil data do not indicate that high releases of plutonium were ever a health problem.
  4. Neither the metal nor the dioxide forms of plutonium (two chemical forms used at Mound)are particularly soluble in water. Plutonium binds tightly to soil and will remain in place insoil for many years. Therefore, the soil presents us with a cumulative record of plutoniumreleases from Mound [1, 10]. The soil does not typically bind tritium very well, however,and soil does not serve as a cumulative record of tritium releases(1). With the exception ofplutonium-238 contamination in the Miami-Erie Canal, which resulted from a pipelinebreak and ground spill, the soil data do not show any plutonium-238 anomalies near theplant. We might expect such anomalies if large air releases escaped the detection of the air-sampling efforts. What the regional soils data show is that plutonium-238 concentrationsdecrease as distance from the Mound Plant increases [11]. This information at least tells usthe most likely areas where air releases would have had the greatest impact: areas close tothe plant. Department of Energy, Ohio Environmental Protection Agency, and ATSDR andthe National Air and Radiation Environmental Laboratory soil samples taken near theMound Plant do not show that plutonium-238 is a health problem today, and so plutonium-238 was not likely a health hazard in the past.

We conclude that the plutonium-238 and hydrogen-3 air releases from the Mound facility were never a public health hazard and that we have sufficient available data to make this conclusion.

Plutonium-238 in Water

In 1960, plutonium solid and liquid wastes were handled as "packaged waste" and were shipped off site for disposal. Mound's environmental reports issued until 1965 state that there were no direct discharges of plutonium into the waterways [12]. In 1965, Mound scientists began reporting plutonium-238 concentrations in the Mound drainage ditch, which flows from the site into the Miami-Erie Canal and from there into the Great Miami River. In 1967, Mound scientists began reporting plutonium concentrations in the Great Miami River at the same locations where they were reporting polonium-210 concentrations.

Although we do not have data on plutonium-238 concentrations in the Great Miami River before 1967, we have data for plutonium-238 in the Mound drainage ditch dating from 1965 [13]. The highest concentration of plutonium-238 reported in the Mound drainage ditch was in 1967. The highest reported releases of plutonium-238 in water to the environment were for the years 1968 and 1969 [2]. Therefore, it appears that we have data on plutonium-238 concentrations in the river for the years when releases were the highest. If we consider that someone could swallow water from the Great Miami River while swimming at the Chautauqua Dam recreational facility, and we assume this person swallowed the highest concentration of plutonium-238 measured at this location, the radiation dose the person would have received is much less than 1 millirem (mrem). This amount of plutonium-238 does not pose a health hazard.

In 1971, Mound scientists reported hydrogen-3 and plutonium-238 concentrations in Miamisburg municipal drinking water. They continued, in subsequent years, to report tritium concentrations in Miamisburg water, but they didn't report plutonium in city water in their annual environmental reports again for another 4 years. When they started again (1975), they also began reporting plutonium-238 in the private wells in and near Bud's Trailer Park. Among all the municipal and private wells data, the highest concentration of plutonium-238 reported, 0.491 picocuries per liter (pCi/L), was in Miamisburg's water in 1971 [14]. (This sample was taken from a resident's tap, not a municipal well.) However, even if people had used only this water for drinking, cooking, and bathing, they would have received an annual radiation dose from the plutonium of less than 1 mrem. This amount of plutonium-238 does not pose a health hazard.

We also considered whether plutonium-238 in Miamisburg's municipal water would have been a health hazard during 1967, when releases of plutonium-238 in water from the Mound facility were highest. Plutonium-238 releases in water in 1967 were about 16 times higher than those in 1971. We estimated that a person using Miamisburg's water for all purposes in 1967 would have received, at the most, no more than approximately 6 mrem. This dose includes contributions from plutonium-238, polonium-210, and hydrogen-3. This amount of radiation does not pose a health hazard.

We conclude, therefore, that plutonium-238 in the area waterways has never been a public health hazard.

Other Radionuclides

Mound scientists began studying a large variety of radioisotopes besides polonium-210, plutonium-238, and hydrogen-3 during the 1950s. These radioisotopes included actinium-227, radium-226, thorium-230, and protactinium-231 [2]. Many of these radioisotopes were used in smaller quantities (laboratory scale) than polonium-210, plutonium-238, and hydrogen-3. Wastes generated from these Mound programs were recycled or contained for off-site shipment, and there are fewer environmental data available for them than for polonium-210, plutonium-238, and hydrogen-3. Many of these radioisotopes were (and are) quite valuable and in some cases, recovery of these isotopes for resale was the purpose of the program. Neither the records of releases and spills nor the more recent characterization of the off-site soils and water indicate that these radioisotopes were ever a public health hazard [4, 11, 15, 16, 17].

Mound officials began publishing the concentrations of plutonium-239 in on-site and off-site air samples with the 1975 annual environmental data and concentrations of uranium-233, -234, and 238 in surface water with 1978 data. They later expanded monitoring programs for each of these radionuclides. The data for plutonium-239 and the uranium isotopes indicate that the levels of these radionuclides in the environment have always been very low and that they have never been a public health hazard.

References

  1. US Department of Energy, Albuquerque Field Office, Environmental Restoration Program. Remedial investigation/feasibility study, Operable Unit 9, site-wide work plan, field sampling plan, Mound Plant, Miamisburg, Ohio. Volume I, work plan text (sections 1-15). Final;1992 May.

  2. US Department of Energy, Albuquerque Operations Office, Environmental Restoration Program. Operable Unit 9, site scoping report volume 7- waste management report, Mound Plant, Miamisburg, Ohio. Draft Revision 0;1991 Nov.

  3. EG&G Mound Applied Technologies, Environmental Technology & Monitoring Section. Mound site environmental report for calendar year 1994. US Department of Energy. MLM-3814;1995 May.

  4. US Department of Energy, Albuquerque Operations Office, Environmental Restoration Program. Operable Unit 9, site scoping report volume 11- spills and response actions, Mound Plant, Miamisburg, Ohio. Draft final revision 0;1992 Jan.

  5. U.S. Environmental Protection Agency. AIRDOS-EPA: A computerized methodology for estimating environmental concentrations and dose to man from airborne releases of radionuclides, EPA 520/1-79-009, 1979 Dec.

  6. U.S. Environmental Protection Agency. User's guide for CAP88-PC, Version 1.0, EPA 402-B-92-001, 1992 Mar.

  7. Department of Energy. A method for calculating radiation doses from radioactivity released to the environment, Oak Ridge National Laboratory, Oak Ridge, Tennessee, ORNL-4992, 1976.

  8. International Commission on Radiological Protection. Radiation protection. ICRP Publication 26. Pergamon Press, Oxford, England, 1977 Jan.

  9. International Commission on Radiological Protection. Radiation protection. ICRP Publication 30, Part I, Limits for intakes of radionuclides by workers, A report of Committee 2 of the ICRP. Pergamon Press, Oxford, England 1978 Jul.

  10. Farmer BM, Carfagno DG. Stability of plutonium contaminated sediments in the Miami-Erie Canal. Mound Facility, Monsanto Research Corporation, US Department of Energy. MLM-2483 UC-11;1978 Mar 1.

  11. EG&G Mound Applied Technologies, Environmental Restoration Program. Operable Unit 9, Regional soils investigation report, Mound Plant, Miamisburg, Ohio. US Department of Energy. Revision 0;1995 Mar.

  12. Adams PC, Meyer HE. Environmental monitoring report: July - December, 1964 and 1964 summary. Monsanto Research Corporation, Mound Laboratory, US Atomic Energy Commission. MLM-1241; 1964 Dec 31, Issued 1965 Mar 26.

  13. Adams PC, Meyer HE. Environmental monitoring report: January - June, 1965. Monsanto Research Corporation, Mound Laboratory, US Atomic Energy Commission. MLM-1275; 1965 Jul 16.

  14. Westendorf WH. Environmental control program, monthly report. Monsanto Research Corporation. September 22, 1971. (August 1971 report)

  15. EG&G Mound Applied Technologies, Environmental Restoration Program. Residential, municipal, and industrial well investigation, Operable Unit 9, Mound Plant, Miamisburg, Ohio. US Department of Energy. Technical report, revision 0;1995 Apr.

  16. US Department of Energy. Operable Unit 9 Surface Water and Sediment Investigation Report, Mound Plant, Miamisburg, Ohio, Technical Memorandum revision 0, April 1996.

  17. Agency for Toxic Substances and Disease Registry. ATSDR and NAREL environmental data tables. Cover letter to Mr. Arthur W. Kleinrath, DOE, 1996 Feb 22.

1. The soil does not provide a record for polonium-210 releases either, because this radionuclide has a 138.4-day half-life. All the polonium-210 released in the 1950s has decayed and is long gone from Mound and Miamisburg area soils. Plutonium-238, on the other hand, has an 87.7-year half-life, and more than half of it released in 1960 should still be in area soils.


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