Assessing the Human Health and Ecological Risk of Tritium Associated with Vermont Yankee Brooke Churas, Allison Rapp, Kacy Roeder, Natasha Yandow

Background Information What is tritium? - Radioactive isotope of hydrogen - Low energy beta emitter - Same physical, chemical, pharmalogical properties as hydrogen Where does tritium come from? - Naturally present in the environment in small amounts as: Tritiated water (HTO) Gaseous tritium (HT) Organically bound tritium (OBT) - Byproduct of nuclear fission What are the regulatory limits on tritium? - The EPA sets limits on tritium in drinking water at 20,000 picocuries per liter n_Sunset/Ball%20HydroCarbon%20Chrono/IM G_7753.jpg

Understanding Units 1 curie = amount of material that will produce 3.7 x nuclear decays per second. 1 becquerel = amount of material which will produce 1 nuclear decay per second. 1 curie = 3.7 x becquerels. 1 picocurie = 1x curies 1 Sievert = 100 Rem

Tritium and Vermont Yankee: Department of Health Timeline January 7, 2010 – tritium contamination reported February 14, major source of tritium leak was identified Soil and water testing confirm pathway of contamination through the discovery of cobalt-60, manganese-54, zinc-65 and cesium-137 Tritium concentrations have been decreasing in samples from groundwater monitoring wells, confirming that the leak has been stopped. Increase in frequency and number of water and environmental samples Contaminated groundwater found to move west to east into the Connecticut River. March- Rigorous monitoring continues April- new groundwater well in service Continued testing shows no tritium in excess of the lower limit for detection (Vermont Department Health 2010)

GZ-1: <LLD GZ-2: <LLD GZ-3: 52,000 GZ-4: 2,400 GZ-5: <LLD GZ-6: <LLD GZ-7: 757,000 GZ-8: No sample; dry well GZ-9: <LLD GZ-10: <LLD GZ-11: 750 GZ-12: 267,000 GZ-13S: <LLD GZ-13D: 1,200 GZ-14S: 258,000 GZ-14D: <LLD GZ-15: 710,000 GZ-16: <LLD GZ-17: <LLD GZ-18: no well yet GZ-19S: <LLD GZ-19D: <LLD GZ-20: 130,000 GZ-21: million Most recent well results in (pCi/l) or below the lower level of detection (<LLD).

Goal To combine evidence of the health impacts of tritium with case studies and current knowledge pertaining to the Vermont Yankee controversy in order to provide a risk assessment of the Vermont Yankee tritium leak to human and environmental health.

Objectives Compare case studies with the situation at Vermont Yankee Use lab studies to assess health effects of tritium on human and non-human organisms Study biological pathways of tritium in plants and in the human body Utilize information given during interviews with State Toxicologist Bill Bress, Radiological Health Chief Bill Irwin Present key recommendations regarding Vermont Yankee while accounting for uncertainties

Tritium Sources Natural tritium is created at a rate of kg/yr Natural tritium is created at a rate of kg/yr Nuclear sources contribute 0.06 kg/yr Nuclear sources contribute 0.06 kg/yr Atmospheric weapon tests totaled 560 kg by 1963 but by 2008 were reduced to about 40 kg Atmospheric weapon tests totaled 560 kg by 1963 but by 2008 were reduced to about 40 kg (Boyer 2009 )

The Tritium Cycle Tritium is most commonly found as tritiated water, tritiated methane and tritiated molecular hydrogen. Tritium is most commonly found as tritiated water, tritiated methane and tritiated molecular hydrogen. Tritiated water moves through the water cycle as normal water does, moving through water bodies, atmosphere, soils, groundwater, largely ending up in oceans. Tritiated water moves through the water cycle as normal water does, moving through water bodies, atmosphere, soils, groundwater, largely ending up in oceans. ges/groundwater.gif

Findings: Tritium in Plants Plant Absorption of Tritium Plants take in tritium through their foliage and through soil Most tritium is quickly released back into the atmosphere through transpiration Tritium absorbed by a plant will quickly reach equilibrium with the tritium in the soil Tritium absorption depends on several factors Plant type, stage of development, water mass of organism, leaf area index Stomatal resistance, stomatal gating, stomatal gating Soil type, soil bacteria Meteorological conditions, temperature, relative humidity (Boyer 2009)

Differences in plant absorption of TritiumDifferences in plant absorption of Tritium C3 plants absorb more atmospheric tritium during the day than at nightC3 plants absorb more atmospheric tritium during the day than at night C4 plants typically contain less tritium than C3 plantsC4 plants typically contain less tritium than C3 plants Lichen, mosses and fungi absorb tritiated water rapidly because they lack a cuticle and stomatal apparatusLichen, mosses and fungi absorb tritiated water rapidly because they lack a cuticle and stomatal apparatus Findings: Tritium in Plants (Boyer 2009) b5bb87aee74a86fdae78ed564e663/stom a.gif

Boyer’s ConclusionsBoyer’s Conclusions It is assumed that high levels of tritium exposure will cause DNA mutations but the environmental impacts are minimized by extremely limited exposure.It is assumed that high levels of tritium exposure will cause DNA mutations but the environmental impacts are minimized by extremely limited exposure. Based on Boyer’s findings the environmental health impacts of the Vermont Yankee tritium leaks will not be significant.Based on Boyer’s findings the environmental health impacts of the Vermont Yankee tritium leaks will not be significant. Findings: Tritium in Plants (Boyer 2009)

Findings: Studies on Rats and Mice Yamamoto (1998) orally exposed mice continuously throughout their lives: - High (5.0 x pCi/L – 1.6 x pCi/L) dose rates mice died of haematopoietic injury. - Moderate (1.0 x pCi/L – 2.5 x pCi/L) dose rates the mice died from tumor development. A threshold dose rate was determined to be 12mGy/day. The lowest dose rate of radiation that the mice were exposed to was 2.35 x 10 8 pCi/L. Vermont Yankee Maximum: 2.5 x 10 6 pCi/L (Bress 2010). Cancer-causing thresholds in mice are not being crossed.

(Vermont Department Health, 2010) GZ-1: <LLD GZ-2: <LLD GZ-3: 52,000 GZ-4: 2,400 GZ-5: <LLD GZ-6: <LLD GZ-7: 757,000 GZ-8: No sample; dry well GZ-9: <LLD GZ-10: <LLD GZ-11: 750 GZ-12: 267,000 GZ-13S: <LLD GZ-13D: 1,200 GZ-14S: 258,000 GZ-14D: <LLD GZ-15: 710,000 GZ-16: <LLD GZ-17: <LLD GZ-18: no well yet GZ-19S: <LLD GZ-19D: <LLD GZ-20: 130,000 GZ-21: million Most recent well results in (pCi/l) or below the lower level of detection (<LLD).

Findings: Studies on Rats and Mice Effects of chronic ingestion of tritiated food is perhaps worse than the effects of chronic ingestion of tritiated water. Tritium was retained longer in body tissues when ingested with food. Greatest risk might come from the ingestion of organically bound tritium being consumed as food. Study by Takeda (2001): Bress (2010) assured that ingestion of tritiated water is the main concern.

Chemical half life = yearsChemical half life = years Biological half life:Biological half life: 10 days for HTO (90% of uptake)10 days for HTO (90% of uptake) 30 days for OBT (10% of uptake)30 days for OBT (10% of uptake) 450 days for trace amounts450 days for trace amounts Pathways: inhalation, ingestion, absorption through dermisPathways: inhalation, ingestion, absorption through dermis Rate of absorption depends on chemical formRate of absorption depends on chemical form HTO transferred fastestHTO transferred fastest Radiation penetrates 6  m, but human epidermis is  m thickRadiation penetrates 6  m, but human epidermis is  m thick Findings: Tritium in the Human Body

Tritium in the Human Body Travels through same biokinetic pathways as water/organic compoundsTravels through same biokinetic pathways as water/organic compounds Uniform distribution as HTOUniform distribution as HTO Uneven distribution as OBT: stored in adipose tissue and tissue with high multiplication rateUneven distribution as OBT: stored in adipose tissue and tissue with high multiplication rate Replaces hydrogen in all compoundsReplaces hydrogen in all compounds Same physical, chemical, pharmacological propertiesSame physical, chemical, pharmacological properties 99% excreted as HTO and OBT99% excreted as HTO and OBT

Effective dose of OBT is 2.3 times higher than that of HTOEffective dose of OBT is 2.3 times higher than that of HTO Accounts for risk of incorporation into DNA (impacts unknown)Accounts for risk of incorporation into DNA (impacts unknown) Difficulty of dose measurementDifficulty of dose measurement Low number of contamination casesLow number of contamination cases Not highly radioactiveNot highly radioactive To have potential impacts, exposure must be 1000 times the levels found in natureTo have potential impacts, exposure must be 1000 times the levels found in nature Tritium in the Human Body

Effects on human body similar to those observed in plantsEffects on human body similar to those observed in plants Once absorbed, it quickly passes throughOnce absorbed, it quickly passes through Assumptions:Assumptions: DNA mutationsDNA mutations Cell damageCell damage Damage caused from radiation, not from molecule itself!Damage caused from radiation, not from molecule itself! Unlikely that humans will be exposed to high enough concentrations at Vermont YankeeUnlikely that humans will be exposed to high enough concentrations at Vermont Yankee } Exposure to high doses

Studies Long term effects unknownLong term effects unknown Exposed lymphocytes and marrow cells to HTO showed:Exposed lymphocytes and marrow cells to HTO showed: Does not increase RBEDoes not increase RBE Chromosomal aberrations increased but sister- chromatid exchanges did notChromosomal aberrations increased but sister- chromatid exchanges did not No conclusions about uptake via fruits and vegetables should be madeNo conclusions about uptake via fruits and vegetables should be made (Tanaka 1994), (Boyer 2009)

Dose levels account for people living close to siteDose levels account for people living close to site Adults eating fish within a 500 m radiusAdults eating fish within a 500 m radius Sunbathing (100 h/yr)Sunbathing (100 h/yr) Swimming (20 h/yr)Swimming (20 h/yr) Increased risk for certain groups (ex. fisherman)Increased risk for certain groups (ex. fisherman) Risk of exposure extremely lowRisk of exposure extremely low Impacts of Controlled Releases Flamanville, Manche, France news.org/uploadedImages/wnn/Images/F lamanville%203.jpg (Le Guen 2009)

Findings: Case Studies at Savannah River Site (SRS) Savannah River SiteSavannah River Site South CarolinaSouth Carolina Not in operation todayNot in operation today Clean up of past nuclear weapons manufacturingClean up of past nuclear weapons manufacturing te_ISS012-E jpg (Little 2007)

Findings: Case Studies at SRS Cragle et al (1998) Study Study –Mortality of 9,860 white male workers at the SRS, 1952 to 1980 –Little data on actual tritium doses –Estimated doses: 800 employees received > 0.5 mSv per year800 employees received > 0.5 mSv per year 1 employee > 30 mSv per year1 employee > 30 mSv per year Findings Findings –Few indications of excess mortality –18 prostate cancer deaths versus expected deaths –Marginally increasing trend for leukemia at 25 deaths versus expected deaths –Further analysis (Little 2007)

Findings: Case Studies at SRS Richardson and Wing (2007) StudyStudy Association between radiation exposure and leukemia, Association between radiation exposure and leukemia, Doses of tritium, photons, and neutrons were estimatedDoses of tritium, photons, and neutrons were estimated FindingsFindings –Results into 3 different groups: LeukemiaLeukemia Leukemia excluding chronic lymphocytic leukemia (most common type)Leukemia excluding chronic lymphocytic leukemia (most common type) CLL: slow progression, affects lymphoid cells (white blood cells)CLL: slow progression, affects lymphoid cells (white blood cells) Myeloid leukemiaMyeloid leukemia Myeloid: rapid progression, affects the myeloid cells (red blood cells, granulocytes, and platelets)Myeloid: rapid progression, affects the myeloid cells (red blood cells, granulocytes, and platelets) 84 from leukemia, 62 from leukemia excluding CLL, 40 from myeloid leukemia84 from leukemia, 62 from leukemia excluding CLL, 40 from myeloid leukemia –Excess Relative Risk, respectively: 4.1 Sv -1, 7.7Sv -1, and 12.3 Sv -1 (Little 2007)

Findings: Case Studies at SRS General Issue General Issue –No analysis accounting tritium separately –Difficult to infer much about tritium risks from studies (Little 2007)

Findings: Case Study at Chapelcross Chapelcross Chapelcross –Town of Annan, southwest Scotland –Purpose was to produce plutonium and tritium for UK nuclear weapons program and electricity for grid r_Station_2.jpg (Little 2007)

Findings: Case Study at Chapelcross McGeoghegan and Binks (2001) StudyStudy 2,628 workers assessed, ,628 workers assessed, Tritium doses not availableTritium doses not available FindingsFindings Mortality below that expected for non-tritium exposed for Scotland, England, and WalesMortality below that expected for non-tritium exposed for Scotland, England, and Wales Standardized Mortality Ratio (SMR) <1Standardized Mortality Ratio (SMR) <1 Prostate cancer the only statistically significant positive trend of cancer mortality, 8 deathsProstate cancer the only statistically significant positive trend of cancer mortality, 8 deaths When lag increased, statistical significance eliminatedWhen lag increased, statistical significance eliminated Statistical significance for bronchitis deaths, 6 deathsStatistical significance for bronchitis deaths, 6 deaths Suggestive increasing trend for prostate cancer, based on 12 casesSuggestive increasing trend for prostate cancer, based on 12 cases Cases not monitored for tritiumCases not monitored for tritium All but 2 workers left prior to tritium productionAll but 2 workers left prior to tritium production – (Little 2007)

Findings: Case Study of Canadian Nuclear Workers Zablotska et al (2004) StudyStudy Mortality follow up of 45,468 Canadian nuclear workers, Mortality follow up of 45,468 Canadian nuclear workers, Mean dose exposure of 13.5 mSv/ year, up to 19.7 mSv / yearMean dose exposure of 13.5 mSv/ year, up to 19.7 mSv / year FindingsFindings Mortality due to all cancers and leukemia excluding CLL less than national ratesMortality due to all cancers and leukemia excluding CLL less than national rates All cancers: 531 observed deaths versus 721 expectedAll cancers: 531 observed deaths versus 721 expected Leukemia excluding CLL: 18 observed versus 22.6 expectedLeukemia excluding CLL: 18 observed versus 22.6 expected (Little 2007)

Findings: Case Study of Offspring of Canadian Electric Power Workers Green et al (1997) StudyStudy Instances of congenital abnormalities for offspring of Canadian electric power workersInstances of congenital abnormalities for offspring of Canadian electric power workers Doses included, further analysis for parents with a recorded tritium dose 60 days before conceptionDoses included, further analysis for parents with a recorded tritium dose 60 days before conception 763 case-control pairs of fathers, 165 case-control pairs of mothers763 case-control pairs of fathers, 165 case-control pairs of mothers Abnormalities determined using Canada’s congenital anomalies surveillance systemAbnormalities determined using Canada’s congenital anomalies surveillance system Abnormalities detected within year 1Abnormalities detected within year 1 Each child with an abnormality paired with a random childEach child with an abnormality paired with a random child Ontario system (same year of birth, maternal age, marital status, and birthplace of each parent)Ontario system (same year of birth, maternal age, marital status, and birthplace of each parent) (Little 2007)

Findings: Case Study of Offspring of Canadian Electric Power Workers FindingsFindings Little risk for offspring abnormality when parents exposed to tritiumLittle risk for offspring abnormality when parents exposed to tritium (Little 2007)

Expert Opinions: Expert Opinions: State Toxicologist, Dr. Bill Bress Tritium is a weak beta emitter - Can not penetrate the skin - Ingestion of tritiated water as main route of exposure - Most human cancers are linked to gamma emitters “could not project a dose large enough at this site to be an acute human health risk”. - Consumption of two liters of tritiated water per day, at a concentration of 20,000 pCi/L in order to cause cancer million pCi/L is the absolute maximum concentration of tritium - Tritium is water soluble Low potential for human ingestion of tritiated water - Contamination limited to surface and subsurface levels - No drinking water comes from the Connecticut River Minimal environmental health effects Levels of tritium in the monitoring wells are dropping and the leak has been stopped.

Expert Opinions: Radiological Health Chief, Dr. Bill Irwin Possibility of greater risks Environmental effects not likely because of the dilution. Assumed that someone will drink from the Connecticut River Examples of tritium leaks from nuclear power plants taking place in New Jersey and Georgia. More preventative action - Aboveground pipes - Multiple barriers Routine monitoring and sampling

Conclusions Case studies show that the number of cases of cancer linked with tritium were equal or less than those expected Case studies show that the number of cases of cancer linked with tritium were equal or less than those expected Offspring of those exposed to tritium showed no increased abnormalities over those offspring with parents not exposed to tritium Offspring of those exposed to tritium showed no increased abnormalities over those offspring with parents not exposed to tritium The metabolism of tritium within the human body provides evidence for a minimal risk of cancer The metabolism of tritium within the human body provides evidence for a minimal risk of cancer The location of Vermont Yankee on the Connecticut River has allowed for the dilution of tritiated water The location of Vermont Yankee on the Connecticut River has allowed for the dilution of tritiated water The radionuclide tritium does not exist in high enough concentrations at this site to cause negative human or environmental health effects. The radionuclide tritium does not exist in high enough concentrations at this site to cause negative human or environmental health effects.

Recommendations Continued monitoring of the soil and water surrounding Vermont Yankee to ensure levels of tritium continue to drop Continued monitoring of the soil and water surrounding Vermont Yankee to ensure levels of tritium continue to drop tritium leak as a potential indicator for the possibility of greater risks associated with Vermont Yankee. Consider the tritium leak as a potential indicator for the possibility of greater risks associated with Vermont Yankee. Increase the number of sampling sites in order to ensure high quality monitoring for not only tritium, but other harmful substances that might be leaking from the plant. Increase the number of sampling sites in order to ensure high quality monitoring for not only tritium, but other harmful substances that might be leaking from the plant.

Updates on Yankee Vermont Yankee will be shut down as of 2012 unless it is relicensed in 2011 Vermont Yankee will be shut down as of 2012 unless it is relicensed in 2011 The Vermont House of Representatives has passed a bill requiring Vermont Yankee to set aside 20 million dollars for the decommissioning The Vermont House of Representatives has passed a bill requiring Vermont Yankee to set aside 20 million dollars for the decommissioning

Summary Goal: To combine evidence of the health impacts of tritium with case studies and current knowledge pertaining to the Vermont Yankee controversy in order to provide a risk assessment of the Vermont Yankee tritium leak to human and environmental health. Objectives Use information from - Case studies with the situation at Vermont Yankee - Lab studies on the health effects of tritium on human analogs - Biological pathways of tritium in the human body - Mechanisms of tritium in plants. - Interviews with State Toxicologist Bill Bress, Radiological Health Chief Bill Irwin : Conclusions: - The location of Vermont Yankee on the Connecticut River has allowed for the dilution of tritiated water - The radionuclide tritium does not exist in high enough concentrations at this site to cause negative human or environmental health effects. Recommendations - Continued monitoring tritium leak as a potential indicator - Consider the tritium leak as a potential indicator - Increase the number of sampling sites

Works Cited Boyer, C.; Vinchot, L.; Fromm, M.; Losset, Y.; Tatin-Froux, F.; Guetat, P.; Badot, P. M. Nov Tritium in Plants: A Review of Current Knowledge. Environmental and Experimental Botany, 67, (1), Bress, Dr. Bill (19 March 2010). State Toxicologist, Vermont Department of Health. Interview Irwin, William (19 March 2010). Radiological Health Chief, Vermont Department of Health. Interview Le Guen, Bernard "Impact of tritium around EDF nuclear power plants." Journal of Radiological Protection. 29: Little, M. P. Sep Systematic review of epidemiological studies of exposure to tritium. Journal of Radiological Projection, 28, Takeda, et al "Comparative biokinetics of tritium in rats during continuous ingestion of tritiated water and tritium-labeled food." International Journal of Radiation Biology 77.3: Vermont Department of Health. (2010). Investigation into tritium contamination at vermont yankee nuclear power station. Retrieved from healthvermont.gov/enviro/rad/yankee/tritium.aspx Yamamoto, O., Seyama, T., Iton, H., & Fujimoto, N Oral administration of tritiated water (hto) in mouse. iii: low dose-rate irradiation and threshold dose-rate for radiation risk. International Journal of Radiation Biology, 73(5),