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PUBLIC HEALTH ASSESSMENT

PADUCAH GASEOUS DIFFUSION PLANT (U.S. DOE)
PADUCAH, MCCRACKEN COUNTY, KENTUCKY


  1. Page 132: Researchers from the University of Cincinnati examined people who wereexposed to contaminated ground water. Part of the evaluation included serum levelsof PCBs because PCBs had been detected in nearby surface water and sediment. IfPCBs tend to absorb onto sediments and accumulate, why weren't other people, whohad been exposed to contaminated well water, examined for PCB exposure?
  2. Response: Shortly after the discovery of the contaminated groundwater off site, ten familiesin the potentially affected area were asked to stop using their well water until more completetesting could be done. After further testing only five families had detectable levels of TCEand Tc 99 in their wells. (Two of these households had TCE levels above EPA's drinkingwater standard.) All ten families were offered medical examinations. Before the medicalscreening was done, it was determined that PCBs had been found in local surface waters. Itwas decided to include serum PCB analysis in the medical screening in order to determinethe extent of potential exposure and to prevent confounding effects on interpretation of otherlaboratory test results. PCB levels were below the detection limit except for the results on one individual whose level was within the usual range for non-occupationally exposedpeople.

  1. There were no details regarding PCB exposure in the soil and sediment section(pp.61-70). PCBs were not included in Table 2. Off-site groundwater contaminants (p.17). PCBs were not included in Table 11. ...off-site surface water (p. 57). It wasreported that at one time PGDP had the world's largest inventory of PCBs!
  2. Response: PCBs are mentioned on page 60, and the exposure scenarios are explained. PCBs were not mentioned in Table 2, because they are not an off-site groundwater contaminant. Total PCBs are included in Table 11.

  1. On a chemical by chemical basis what suspected health effects did you look for?
  2. Response: Refer to "Public Health Implications" in the PHA.

  1. What is the acceptable body dose of plutonium?
  2. Response: ATSDR does not look at an "acceptable dose of plutonium". We evaluate thetotal radiation dose to the whole body and to the critical organs from all radioactivematerials that a person may be exposed to. Our minimal risk level (MRL) for whole bodyexposure is 100 millirem (or 0.1 millisievert) per year. We also evaluate the probability ofthe radioactive material deposited in a critical organ to produce cancer or non-cancerdetrimental effects.

  1. Do you believe results from hair analysis fairly represents the body burden for some metals?
  2. Response: No, at this time, we do not believe that hair analysis fairly represents the bodyburden for some metals. For more information on this subject, refer to our website athttp://www.atsdr.cdc.gov/HAC/hair_analysis/index.htm and/or the journal article: Frish M and Schwartz BS. The Pitfalls of Hair Analysis for Toxicants in Clinical Practice:Three Cases. April 2002. Environmental Health Perspectives 110(4):433-436.

  1. If a previously exposed resident (historical releases) continues to be exposed at current deposition rates, are the odds greater that this person will become ill than if they received no further exposure?
  2. Response: Please refer to the third paragraph on page EX-1, which in part states that "undernormal operating conditions, the Paducah Gaseous Diffusion Plant currently poses noapparent public health hazard for the surrounding community...".

  1. Would you say this study considered near-term risk more than long-term risk?
  2. Response: No, we considered both equally.

  1. Are metals released to air found in house dust?
  2. Response: All metals found in the environment can be found in house dust.

  1. If a person ate a "hot" fish instead of sampling a lot of fish would their health risk be greater?
  2. Response: No, we assessed the total dose for a person consuming 20 to 150 fish meals a yearfor 30 years. (Refer to page 115.) If the person ate a "hot" fish and no other fish, their total dose would be lower.

  1. Did you focus more on individual toxic waste sites or more on the entire PGDPreservation?
  2. Response: We did not focus on waste sites. We evaluated potential contaminants releasedfrom PGDP that migrated off site no matter where they originated on the site.

  1. Using the Illinois Central railroad bridge as the dividing line, where are Kentuckywater districts closest intake pipes (both up river and down river)? Illinois waterdistricts intake pipes? (Ohio River water) What is the source of the Water Policy Area water (e.g., river, well, impoundment)?
  2. Response: The Paducah Water Works (PWW) withdraws its water from the Ohio Riverupstream from PGDP. PWW sells water to the West McCracken County Water District thatsupplies water to people in the Water Policy Area. There is also a water intake downstreamfrom Paducah near the junction of the Ohio River with the Mississippi River. USEC useswater from the Ohio River from a separate intake near the TVA plant upstream from BayouCreek.

    1. Did you consider livestock that drank (surface) water? (Mostly beef or milkcattle?)
    2. Response: Yes, we considered livestock as a media for human exposure but not for the health impact to livestock. (Mostly beef cattle, but both were considered.)

    1. How many head of beef cattle are raised within 4 km of PGDP?
    2. Response: Contact the University of Kentucky's Cooperative Extension Service,2705 Olivet Church Road in Paducah for current and/or historic estimates. In 1998,in McCracken County, there were approximately 350 dairy cattle and 4,000 beefcattle which includes both mature cows and calves.

  1. Concentrations of metals in green leafy vegetables are often times higher thanconcentrations on the soil where they are grown. The rate of uptake is often thegreatest in the leafy part that is eaten. Green leafy vegetables should have beenanalyzed for heavy metals.
  2. Response: We agree that green leafy vegetables should have been analyzed if they were present in the local gardens.

  1. Page 74: Why was 1959 selected as the year for sampling broadleaf grass forfluoride?
  2. Response: Broadleaf grass had been routinely analyzed for fluoride since 1958. For ourcalculations, we used the year with the highest annual average concentration recordedoutside the security fence which was 1959.

  1. Would the amount of plutonium found in the residential wells present a health risk to a person drinking and showering in that water?
  2. Response: No plutonium was found in residential wells.

  1. What is the background value for Neptunium 237 in subsurface soil (PGDP)?
  2. Response: All background values (at unspecified depths) were less than or equal to 0.75pCi/g; however, most of the results were less than the detection limit of 0.5 pCi/g. All off-sitesubsurface soil samples (other than background samples) were less than or equal to 0.5pCi/g, the detection limit.

  1. Would a surface soil measurement of 2,938,000 pCi/kg of Technetium 99 in aresidential area pose a health hazard?
  2. Response: Assuming that this concentration of Tc99 is uniformly distributed in the surfacesoil on residential property, and that a young child (one-year to five-years old; worst case)plays in this soil 250 days a year, the radiation dose that this child may receive fromingestion of this soil would be between 1.25 and 2.6 mrem (0.0125 to 0.026 mSV) andwould not pose a health hazard.

  1. Are you satisfied you received complete and reliable information during this health investigation?
  2. Response: The data that we have received and evaluated are adequate for the public healthconclusions. Significant data gaps have been identified in our conclusions and recommendations.

  1. Are you satisfied that USEC/PGDP has implemented adequate waste minimizationprocedures for their primary operations and that those procedures are protective offuture community health? Have those waste minimization processes resulted in anactual reduction in the total amount of waste generated?
  2. Response: This document is not assessing the adequacy of USEC's waste minimizationprocedures; however, we looked at how the waste handling procedures of DOE have andcould still affect the off-site community. For DOE, their waste volume will increase duringthe clean-up processes unless it is shipped off site and if proposals to treat some waste on siteare not approved. The major waste problem potentially affecting the off-site community isthe continued storage of the aging uranium cylinders.

  1. Are you satisfied that the three groundwater contaminant plumes identified in this document are the only groundwater plumes coming from PGDP?
  2. Response: From the information that we have reviewed, yes. However, we haverecommended continued groundwater monitoring, and if new information becomesavailable, we will assess the data at that time.

  1. It's KDEP position that ATSDR did not complete a fair evaluation of historical datafor the purposes of determining public health in the area surrounding the PGDPplant. In particular, many of the issues and information in the report (DOE, 2000)does (not) appear to have been adequately addressed. Did ATSDR consider thefollowing specific items in the above-referenced report?
  2. "Over 11 kg of UF6 were purposefully released into the air in at least 11 releases."(P.66)

    Response: Refer to page 38 of the PHA. The original reports we reviewed (which I presumeare the same that DOE investigators reviewed) indicated that the releases involved slightlyless quantities than reported here; however, in either case, these releases did not addsubstantially to the total releases of UF6 from the plant for these years.

    "Diffuse and fugitive emissions of fluorides were not calculated for the site from 1952through 1990." (P.66)

    Response: For our evaluation, we are not as concerned with whether the emissions werecalculated as much as what concentrations the off-site community may have been exposedto. Please note under DOE's discussion of chemical hazards in this same document that"Some off-site chemical hazards were identified as early as December 1957, when aprogram for monitoring gaseous fluorides at the plant commenced. This program was inaddition to the monitoring of fluorides in grass, which had begun some time earlier.Reporting ...and off-site releases of fluorides continued through the 1960s and 1970s." Referto pages 45 and 46 of the PHA for a discussion of what we considered for hydrogen fluoride releases.

    "Sixty-nine . . . airborne releases of more than 10 pounds of uranium each" (p. 65)

    Response: We reviewed these accidental airborne releases of uranium; however, we onlypresented the worst case accident on pages 44 and 45. These smaller releases would not have adversely affected the off-site community.

    ". . . approximately . . . 60,000 kg of uranium was released to the atmosphere between1952 and 1990."

    Response: Refer to Table 8.A. on pages 40 and 41 of the PHA.

    " . . . the use of personal clothing was approved as long as beta doses did not exceed 600 mrad/week"
    "Some workers considered PCB's to be an effective remedy for dry skin"

    Response: This document does not cover worker exposures.

    "(. . . radioactively contaminated materials) were disposed of in various areas outsidethe plant boundary. . . Unauthorized salvaging of scrap materials also occurred." (P.18)

    Response: This was considered; however, during our review, nothing was located that wouldhave produced adverse health effects for the off-site community. If we become aware of new information in this area, we will re-evaluate the situation.

  1. Process water was historically discharged to the North-South Diversion Ditch(NSDD). Hydrochloric acid, sulfuric acid, hydrofluoric acid, nitric acid and aquaregia (a combination of hydrochloric and nitric acid used for dissolving gold) weredischarged to the NSDD. Has ATSDR considered this release and the implication thatmetals including radioactive metals could be caused to migrate toward thegroundwater?
  2. Response: Yes, we considered the acid releases to the North-South Diversion Ditch. We alsoreviewed groundwater monitoring data from this area and did not find metals or radioactivemetals to have been a problem in the drinking water wells. However, we have recommendedthat groundwater monitoring be continued although residents in this area have been providedwith an alternate water supply. For more information on metals detected in the groundwater,refer to the Groundwater section of Environmental Contamination, Exposure Pathways, andPotentially Exposed Populations in the PHA.

  1. Does ATSDR believe tritium, which came to PGDP, poses any potential problem?
  2. Response: No, the information and data that we have reviewed indicate that tritium is not a public health concern at PGDP.

  1. Has ATSDR interviewed the physicians at the West McCracken County Clinic inGrahamville about possible exposures for patients they have evaluated since the1960's?
  2. Response: Yes.

  1. How has ATSDR validated the analytical data used for this Health Assessment?
  2. Response: Most of the data used in this assessment was collected under U.S. EPA'sCERCLA guidance and KDEP oversight. These data collection processes entail rigorousquality control and validation procedures. ATSDR representatives reviewed the qualityassurance/quality control records associated with these data and did not utilize records withsuspect validation. ATSDR has also evaluated the data in relation to environmental trendsand release sources. Specific data outliers were individually assessed to determine potential utility.

  1. Will a copy of the comments and responses arising from the May 1, 2001 publicmeeting in Paducah be included in the final report?
  2. Response: Yes.

  1. The following data are from the draft report (Bechtel Jacobs, 2001). Page viii states that the amounts of Pu, Np, 99Tc, and uranium unaccounted for at the plant are:
  2. Pu 210 g 13 Ci
    Np 14125 g 10 Ci
    99Tc 422,048 g 7150 Ci
    U 6,240 metric tons 210 Ci

    Does ATSDR believe that these radionuclides should be considered in the health assessment?

    Response: These radionuclides were considered in the PHA; however, if additional information becomes available about their disposition and the amount released off site, we will review the information and its potential impacts on our conclusions.

  1. ATSDR has not considered the health of the families of the workers at PGDP in thisreport. KDEP contacted George R. Prince of ATSDR's Toxicology InformationBranch in Atlanta and was informed that it was ATSDR policy to include them.KDEP wants all possible receptors of contamination to be considered and inparticular the families of workers.
  2. Response: There is no information available about the types and quantities of material that aworker may or may not have taken home with him other than speculation. We havereviewed the Medical Surveillance information for the PGDP workers, and we know that theKentucky Radiation Control Program has responded when concerned citizens believecontaminants may be in their home. If more detailed information becomes available on thissubject, we will review the data and the potential effects on our conclusions.

  1. Page EX-1, second paragraph: ". . . the Paducah Gaseous Diffusion Plant currentlyposes no apparent public health hazard for the surrounding community. . . . Thisconclusion assumes the effectiveness of access restriction to Little Bayou Creek, theoutfalls, and the NSDD, the fish advisories issued for Little Bayou Creek, and some ofthe ponds in the Western Kentucky Wildlife Management Area; and existingregulations of discharges to air and surface water."
  2. The Division has the following comments concerning the above statement:

    1. Currently, access is not restricted to Little Bayou Creek so a conclusion of protectiveness based on access restriction appears to be inappropriate;
    2. Currently, access is not restricted to any of the outfalls so a conclusion ofprotectiveness based on access restriction appears to be inappropriate;
    3. Currently, access is not restricted to the NSDD so a conclusion ofprotectiveness based on access restriction appears to be inappropriate;
    4. Currently, access is not restricted to the Western Kentucky WildlifeManagement Area (WKWMA) so a conclusion of protectiveness based onaccess restriction appears to be inappropriate;
    5. Although fish advisories have been in effect for Little Bayou Creek and someof the ponds in the WKWMA these waters continue to be a resource forrecreational users;
    6. Historically, discharges from some of the outfalls of the plant exceeded theapplicable KPDES permit allowances. These areas comprise locations whererecreational users could be exposed to process water coming from the PGDP.

    Response: Access restrictions include postings (e.g., no trespassing, no digging, or fishadvisory warnings) and/or physical barriers (e.g., fencing, wires, or ropes). We did notsuggest that access restrictions were needed for the entire WKWMA. One of ourrecommendations is to continue to restrict access to Little Bayou Creek, the outfalls, and theNorth-South Diversion Ditch and to determine if existing signage adequately restricts publicaccess to the southwest inactive landfill and the adjoining area. If the access measures havenot been effective for the North-South Diversion Ditch, Little Bayou Creek, the outfalls, orthe ponds on the WKWMA, then the adequacy of these restrictions should be evaluated bythe Kentucky Department for Environmental Protection or the Kentucky Department of Fishand Wildlife Resources. Although we have seen a person fishing in one of the posted pondsat the WKWMA, we have not seen individuals fishing, wading, or drinking water from theoutfalls or anywhere along Little Bayou Creek or the North-South Diversion Ditch duringour visits to the site.

    1. Page EX-3, 1st paragraph: The population of concern does not accuratelyportray the number of residents and other persons that are potentiallyexposed to chemicals from the plant. This number does not include thenumerous hunters, fishermen, and recreational visitors to the area.
    2. Response: On pages EX-2 and EX-3, we discuss the use and limitations of availablehealth outcome data. Hunters, fishers, and recreational visitors to the area would notbe included in this data unless they lived in the county. We specifically evaluatedpotential exposure to hunters, fishers, and WKWMA visitors in the PHA. None ofthese exposures resulted in exposure doses that would cause adverse health effects.

    1. Page 94, section Identifying Potentially Affected Groups, 2nd paragraph: Lackof knowledge should not substantiate the decision to leave out potentiallyexposed people. By not including hunters, fishermen, and recreational visitors,Table 23 suggests that few people are exposed to the chemicals of concern off-site. Due to the close proximity of the WKWMA, the above populations needto be included. In certain areas, these people are possibly the most exposedpopulation around the plant.
    2. Response: As stated in the second paragraph on page 92, Table 24 (formerly Table23) does not include the surface water and biota pathways. We acknowledge thatmost people potentially exposed through these pathways would be hunters andfishers; however, most of these people would not be exposed to maximum surfacewater concentrations at the outfalls, in the North-South Diversion Ditch, or in LittleBayou Creek (since these would not be ideal places for fishing or hunting). Also, theonly biota contaminants of concern are polychlorinated biphenyls (PCBs) in fish. Inthe Environmental Contamination, Exposure Pathways, and Potentially ExposedPopulations section of the PHA, we evaluated potential exposure to hunters, fisherpersons, and recreational visitors from these pathways and concluded that theirpotential exposures would not result in adverse health effects. Consequently thespecific number of individuals potentially exposed does not alter the public healthconclusions.

  1. Page 7, section Land Use and Natural Resources, 3rd paragraph: The Agreement inPrincipal (AIP) program routinely tests select residential wells to ensure that thecurrent water policy box is protective.
  2. Response: The information as stated in the report was provided when we inquired about the testing of new wells being drilled outside the Water Policy Area.

  1. Page 12, section Environmental Contamination, Exposure Pathways, and PotentiallyExposed Populations, 1st paragraph: What does ATSDR mean by the term "spillareas"? Also, what information was used to reach this supposition?
  2. Response: "Spill areas" are areas where contaminants got into the soils by either intentionalor unintentional acts but do not include landfills. They are sources or potential sources for groundwater contamination. (Refer to Table 1.)

  1. Page 16, section Contaminants of Concern, 1st paragraph: "The first phase ofscreening involved identifying contaminants detected above media-specificcomparison values in on-site or off-site well samples." These media-specificcomparison values are also called background samples. The problem still remains atPGDP that most background samples are contaminated with anthropogenicchemicals many of which are directly related to facility activities (e.g., 99Tc). How cana sample be used as a background sample for inorganic compounds if there is organicchemical contamination from the facility in the area termed background?
  2. Response: Media-specific comparison values are NOT background samples. Please read Appendix C of the PHA.

  1. Page 20, section Contaminants of Concern, 2nd paragraph: U-234 and Th-230 (twoprecursors to radon 222 in the degradation of U-238) have been found at PGDP.KDEP believes that some of the radon 222 did not come from PGDP. Please clarifythe text.
  2. Response: We do not understand this comment, or what the commentor wants clarified. Theuranium decay chain involves a number of different radionuclides, each with differingchemical and physical properties. Off-site monitoring data do not show the presence ofradium 226 (the immediate precursor of radon 222) at levels of concern in soils, surfacewater, and/or groundwater; therefore, the elevated concentrations of radon 222 in thegroundwater are probably coming from natural deposits of radium 226 in the substrate.

  1. Page 26, section Current Exposure, 1st paragraph: Based on current data, thenorthwest plume does not appear to be discharging into Bayou Creek. However, it isdischarging into Little Bayou Creek (A.E. Fryar et al, 2000). Trichloroethene (TCE)and 99Tc have been detected seeping from springs into Little Bayou Creek for at leasta year. In regards to discharge of contaminated groundwater into the Ohio River,based on the hydrogeologic conditions (i.e., geological setting and groundwater flowcharacteristics) it is possible that contaminated groundwater from the PGDP couldmigrate and discharge to the Ohio River. However, current groundwater plumemaps published by the Department of Energy (DOE) do not indicate thatgroundwater contaminated at levels of concern is discharging directly into the OhioRiver.
  2. Response: We have changed "Big Bayou Creek" to "Little Bayou Creek" in this paragraph.We acknowledge the remainder of the comment, but the statements do not seem to contradictthe information already in the PHA. Published plume maps are static interpretations ofcomplex and dynamic groundwater conditions.

  1. Page 29, Potential Future Exposure, 2nd paragraph: KDEP, as does DOE, hasconcerns with new residents or landowners installing supply wells in the areas ofgroundwater contamination, and agrees with the restriction. As a result, DOE ispursuing the option of purchasing water rights from landowners in the affected areas.Please contact DOE for clarification on their position and incorporate into thisreport.
  2. Response: We acknowledge this comment. DOE is still pursuing this option.

  1. Page 39, Table 7: Pages 45 and 46 of the DOE EH Phase II Independent InvestigationReport (DOE, 2000) refer to puffs, jetting and midnight negatives. It does not appearthat this information is included in Table 7. KDEP requests that this information beincluded as an attachment to Table 7.
  2. Response: "Puffs" are minor releases from the process equipment that may affect a worker inclose proximity but would not add substantially to the quantities released off site. "Jettings"were also minor releases resulting from purging process gas system equipment of UF6 andHF and releasing the resulting gaseous mixture from jets on top of the process building roof.These smaller releases would not have adversely affected the off-site community. "Midnightnegatives" refers to using the roof jets to accelerate the attainment of an adequate UF6negative in the system and involved much larger quantities of UF6. Although the quantitiesreleased and the number or frequency of these releases are unknown, we will add "midnightnegatives" to Table 7 since they may have been a major release source until the mid-1980s.

  1. Page 40, section Air - Background, 4th Paragraph: The algaecide Orocol, a sodiumchromate solution, was used for the recirculating water-cooling systems. KDEP findsno indication of zinc in this solution. Phosphate is currently used to address algalgrowth. Does ATSDR have data that indicates zinc was used in the cooling towerwater?
  2. Response: Orocol GDP, a special Betz formulation of hexavalent chromate, zinc, andphosphate, was selected by the AEC as the preferred corrosion inhibitor in the gaseousdiffusion plant cooling towers in the 1950s. It was used in the recirculating water systemsuntil the late 1970s. Although most of the environmental studies performed around the GDPcooling towers concentrated on chromium releases, information on zinc environmentalconcentrations can be found in F. G. Taylor, Jr.'s article, Chromated Cooling Tower Driftand the Terrestrial Environment: A Review, Nuclear Safety, Vol. 21, No. 4, Jul-Aug 1980.

  1. Page 50, section Airborne Exposure Pathways: The airborne exposure pathwaysincluded reported released quantities from process operations at the plant. Volatileand semi-volatile organics that were found in surface water, sediment, and soil werenot included. Leaving this material out of the calculations reduces the real risk to off-site receptors. KDEP requests that ATSDR calculate the risk to recreationalreceptors, residential receptors, and WKWMA workers.
  2. Trichloroethylene (TCE) represented the largest source of organic vapors at PGDP.Airborne releases of TCE are discussed in Appendix G of the PHA. We also evaluated thelevels of TCE (and other organic substances) in surface water, soil, and sediment. Theconcentrations of TCE in off-site surface water samples ranged from 1 to 51 µg/L with thevast majority of the samples reported as non-detectable. The maximum value was found atan outfall with the highest level in an off-site creek of 5 µg/L. Although TCE may be in thesurface water onsite, it partitions rapidly to the atmosphere from surface water and is aninsignificant contributor to air releases once it gets off site. Exposure to TCE in off-sitesurface water by ingestion and dermal contact were evaluated in the Surface Water section of the PHA. Also, concentrations of TCE and other volatile organics in soil and sediment offsite were insignificant and would not increase the potential exposures to recreational orresidential receptors or WKWMA workers.

  1. Page 52, Table 10: Why did ATSDR not evaluate uranium hexafluoride (UF6) or anyother radioactive material that may have been transported, by air, across the OhioRiver? Since the prevailing wind is from the south and since it is suspected that anunknown amount of air was released from PGDP. KDEP requests that ATSDR useit's model (Appendix H) to evaluate the amount of radioactive material that crossedthe river.
  2. Response: We considered anyone who may have been exposed at a level of concern but didnot find that air releases from PGDP would have adversely affected anyone in Illinoiswhether from chronic or acute releases. Existing air models predicted that UF6 (and UO2F2and HF) would disperse to non-measurable concentrations well before it passed over theOhio River.

  1. Page 53, section Surface Water, 1st paragraph: The official name of Big Bayou Creek is "Bayou Creek."
  2. Response: The name has been changed to the official name "Bayou Creek".

  1. Page 53, section Surface Water, 2nd paragraph: Regulations do not guarantee thatchemicals of concern have not been discharged to Bayou and Little Bayou Creekthrough the KPDES outfalls. Has ATSDR reviewed available KPDES data toevaluate if any exceedances of the permitted discharge levels have occurred?
  2. Responses: Yes, exceedances have occurred. However, as human exposure is limited in these areas, the concentrations would not have caused adverse health effects.

  1. Page 54, section Contaminants of Concern, 2nd paragraph: "Concentrations of mostsurface water contaminants were log-normally distributed, meaning that a fewsamples had high concentrations while most of the samples had much lowerconcentrations. Consequently, the estimated exposure doses were calculated using the67th percentile of the concentration distribution."
  2. This method of calculating the concentration term is not acceptable for determiningthe concentration term in Kentucky. Both KDEP and US Environmental ProtectionAgency (EPA) Risk Assessment Guidelines require the concentration term to becalculated using the 95th Upper Confidence Limit of the Mean (UCL) (separateequations are available for normal and log-normal distributions). Calculations usingthe 67th percentile will greatly reduce the intake values. As a result, the risk and/or hazard results will be underestimated.

    Response: ATSDR is NOT looking at the data to determine if the levels meet regulatoryrequirements. We evaluate the activities at the specific site and the distribution of thecontaminants to determine conservatively what someone may be exposed to and the potentialhealth implications. As stated on page 52, the concentrations of most surface watercontaminants were log-normally distributed, meaning a few samples had high concentrationswhile most of the samples had much lower concentrations. No one at this site would beexposed to the 95th percentile concentration levels continuously based on the locations of thehighest concentrations and the frequency of potential exposure. Use of the 67th percentile in human exposure calculations for this site is health protective.

    1. Page 63, section Contaminants of Concern, 1st paragraph: KDEP asks that ATSDR be protective and treat all chromium as Cr VI for this document.

    2. KDEP would also like to see chromium listed as a potential air pollutant.

    Response: ATSDR re-evaluated the soil and sediment sampling data for chromium andhexavalent chromium at the site (2,823 samples) and compared the results to the health-based comparison value for exposure of children to hexavalent chromium. (Thesoil/sediment comparison value is based on a 10-kilogram child ingesting 200 milligrams ofsoil every day.) Out of 2,823 samples, seventeen exceeded this comparison value. Three ofthese samples were collected from the C-616 sludge lagoon (1989, 1990, 1991), seven weresediment samples from Little Bayou Creek (1991, 1996, 1999), one was a surface soilsample near Little Bayou Creek (1991), two were soil samples near the North-SouthDiversion Ditch (1991, 1999), one was a sediment sample from the North-South DiversionDitch (1999), one was a surface soil sample taken near the southwest landfill (1994), andtwo were on-site soil samples. These are not locations where a child would be consuming200 milligrams of soil every day. None of the results exceeded the health-based comparisonvalues for adults.

    Airborne chromium (hexavalent chromium) was evaluated as a potential air pollutant asdiscussed on pages 47 and 48. Maximum off-site air concentrations were estimated to be atleast 100 times lower than ATSDR's comparison values. Therefore, we see no reason toselect it as a contaminant of concern for the air exposure pathway.

  1. Page 64, Scenario 1 WKWMA Workers and Visitors: Some WKWMA workers andtheir families lived on the WKWMA. Therefore, KDEP recommends that bothScenarios I and II be evaluated for this population.
  2. Response: ATSDR was aware that some of the WKWMA workers and their families livedon the WKWMA and evaluated this situation during the health assessment process. Thefamilies were considered in the residential scenarios, and the levels of contamination thatthey may have been exposed to are included. A narrative has been added to clarify thepotential exposure of workers who also live at the WKWMA.

  1. Page 73, section Contaminants of Concern, 4th paragraph: Data collected by KDEPshows that PCB levels in fish have not decreased and are at comparable levels to1988. ATSDR does not reach any conclusion in this section. How does the ORNL dataand the UK data compare to human risk from consumption of PCB contaminatedfish? In addition, separate sources of data should be evaluated independently and nottogether. Has ATSDR evaluated the numerous AIP sampling collections andsubsequent PCB analysis of fish in LBC and BC since 1997?
  2. Response: Please refer to the PCB section on pages 114 through 117 in the Public HealthImplications section of the PHA for a discussion of the likelihood of health effects. ATSDRhas not evaluated PCBs in fish analysis data since 1997. ATSDR requested that KDEPprovide all relevant environmental sampling data but has not received any reports on PCBsin fish since 1997.

  1. Page 76, Tables 17 A and B: Beef, pork, chicken, dairy products, honey, etc. from theproperty around PGDP have not been evaluated. Therefore, the Table 17B misleadsthe reader to believe a complete biota assessment has been conducted. Please correct.
  2. Response: There is no need to "correct" these tables (currently Tables 18A and 18B). The tables list the types of biota sampled.

  1. Page 77, 2nd paragraph and Table 18: ATSDR states that an adult recreationalfisherman will consume 8 grams/day (0.008 kg/day) and that 20% of that which isconsumed is contaminated. This means that a recreational fisherman off-site ofPGDP will consume 584 grams (1.2 lbs) per year of contaminated fish.
  2. KDEP default values for recreational anglers are 6 grams/day (0.006 kg/day, 4.63lbs/year) but designates that all (100%) the fish consumed from the location ofconcern. This does not take into consideration the subsistence fisherman that mayconsume more per meal (284 grams, 0.62 lbs) and more meals (48) per year (USEPA,1989. Risk Assessment Guidance for Superfund). ATSDR results will likelyunderestimate the risk to recreational fishermen off-site. Please correct.

    Response: For Paducah we interviewed a number of subsistence fisher persons from the Cityof Paducah and found that they fish in a number of lakes, ponds, and rivers near Paducah,not just at WKWMA. We also discussed the frequency that they eat fish versus other sourcesof protein. Over the years ATSDR has done a great deal of research in this area. We haveconducted a number of health studies on human consumption of fish while studyingexposure to various contaminants. Through personal interviews with anglers and subsistencefisher persons and monitoring recent research in this area, ATSDR has determined that these values are realistic and health protective for this site.

  1. Page 78, Table 19A: Please revise the appropriate portions of the text to reflect thatthe "Estimated Total Exposure Dose per Chemical" and the "Health Guideline" forarsenic are equal. Are there any known synergistic effects for the metals listed inTable 19A?
  2. Response: The question is not if arsenic is equal to the health guideline but whether itexceeds the health guideline. The health guidelines have been divided by several safetyfactors to account for animal research versus human response, the most sensitivepopulations, etc.; therefore these conservative values are orders of magnitude below levelswhich we would expect to see any adverse effect including any cumulative, synergistic, orantagonistic effects. However, since arsenic is discussed under the Specific Substancessection of Public Health Implications for elevated levels in the groundwater, a discussion of arsenic in biota has been added.

  1. Page 78, Table 19A: What criteria or process did ATSDR utilize for developing a listof contaminants of concern (COCs)? Was there a list of COC's for all media at thesite and did ATSDR address the cumulative risks from exposures to all COCs in allmedia?
  2. Response: The contaminant of concern selection process is described on page 10(Introduction to the Environmental Contamination, Exposure Pathways, and PotentiallyExposed Populations section) with additional information in Appendix C and the PublicHealth Implications section of this PHA. ATSDR addressed cumulative effects of thecontaminants of concern in all media on pages 91 and 92 and in Table 24 of the PHA.

  1. Page 82, section Current Exposure, 3rd paragraph: The text should be modified toindicate that the uptake of PCBs by plants could be widely variable (i.e., in somesituations the uptake can be significant [M. Webber et al., 1994]). However, to datesamples collected at the PGDP by DOE have not revealed detectable levels of PCBs inplants.
  2. Response: We do not agree that the document needs to be modified.

  1. Page 86, section Storms, 1st paragraph: KDEP believes that ATSDR has understatedthe possibility of tornadoes at PGDP. ATSDR should expand the text to indicate whatwastes or hazardous materials from all sources could be potentially released in theevent that a tornado strikes the PGDP. There are three potential problems withtornadoes hitting PGDP: (1) It could move and possibly damage some of the new orolder cylinders. If cylinders became ruptured then contamination could be released;(2) Scrap yards are also of concern. If a tornado were to strike, it is very likely thatcontaminated scrap would be transferred to uncontrolled areas; (3) There are a lot ofmetal buildings at PGDP that contain low and high-level radiation waste, hazardousmaterials and waste, and mixed waste. What damage would be done by a tornadohitting any of the cylinder yards, scrap yards, or PGDP buildings?
  2. Response: ATSDR does not agree that the possibility of tornadoes at PGDP was understatedas the information reported in the PHA was based on data recorded by the NationalOceanographic and Atmospheric Administration's National Climatic Data Center. TheStorm section of the PHA was written in response to a public concern about the potentialeffects of various storms on the depleted uranium cylinders stored in the outdoor cylinderyards. Since we do not have the weight or surface dimensions of the scrap in the scrap yardsor the engineering designs for the PGDP buildings, we cannot respond in detail to that part ofthe comment. If a tornado was able to move the scrap off site, then we would need to knowwhat the scrap was contaminated with and the extent of contamination. Presuming that mostof the scrap is primarily contaminated with alpha-emitting radionuclides (i.e., uranium andtransuranics) and heavy metals, the major problems would be the physical hazard from thescrap metal projectile and later ingestion of contamination if the contaminants areremovable. If the buildings were damaged significantly and there was a release of low orhigh-level waste, the most urgent response would be to avoid inhalation of any airbornecontaminants. If the damage resulted in a liquid release, onsite emergency procedures shouldbe able to respond before the community would be affected. Criticality from the physicallocation of the material may also be a problem onsite.

  1. Page 87, section Transportation and Plane Accidents, 1st paragraph: Please clarifywhat cylinders are being transported from PGDP to the Portsmouth GaseousDiffusion Plant.
  2. Response: DOE is not currently transporting any material in cylinders. USEC is transportinglow-enriched material to Portsmouth primarily in 48X cylinders with "Paducah Tiger"overpacks. The 48Y cylinders are used primarily for transporting natural uranium. The 48Gcylinders are used primarily for storage of depleted uranium.

  1. Page 87, section Transportation and Plane Accidents, 2nd paragraph: There havebeen two accidents at Barkley Airport in the last four years. Neither was any threat toPGDP. In one of the PGDP annual safety trainings, USEC modeled the scenario of anairplane hitting the plant. The National Transportation Safety Board (NTSB) has adatabase of all flight accidents. KPDES would like ATSDR to review the USECscenario and request from NTSB the probability of PGDP being hit by an airplane.
  2. Response: We have reviewed the NTSB data on the frequency of airplane accidents and thefrequency of accidents involving hazardous materials in order to determine potential hazardsfor the storage of depleted uranium cylinders and other DOE waste. The scope of this healthassessment reviews DOE activities at the site. USEC emergency plans are reviewed andapproved by the U.S. Nuclear Regulatory Commission.

  1. Page 91, section Concrete Rubble, 1st paragraph: The concrete rubble was includedin Waste Area Group (WAG) 17. Radioactive contamination above levels of concernwas detected in soil at one of the rubble piles. A subsequent action was conducted toremove this contaminated soil. However, the remaining rubble piles were notdisturbed to see if there was contaminated rubble in the center of the piles or in thesoil beneath them. Currently, DOE is moving some of these rubble piles back insidethe plant fence. As a result, the potential for exposure at these former rubble pilelocations may have changed. The soil beneath the former rubble piles is nowpotentially available for exposure. KDEP is currently evaluating the soil beneaththese areas where rubble piles have been removed to determine if health hazardsexist.
  2. Response: We acknowledge this comment, but available data indicate that potentialexposures before moving the rubble piles are below levels of human health concern.Presumably, when the rubble piles are moved, surveys will be performed and any potentialcontamination will be removed; thus, we would not anticipate any potential exposure to the community.

  1. Pages 95 and 96, Table 22: The predominant direction of the wind is to the north-northeast. The potential for gaseous releases from the facility is 360 from the plant.It does not seem that all of the known releases from PGDP are listed in the chart.Specifically, puffs, jetting and midnight negatives, which are cited in the DOE EHPhase II Independent Investigation Report (DOE, 2000), have not been evaluated.
  2. Response: The predominant wind direction was stated on page 9; however, we took intoaccount that potential gaseous releases could occur in any direction from the plant. Bothlong term and short term meteorological data from the Paducah (Barkley) airport have beenused to assess potential exposure. For chronic exposure the potentially affected populationwas along the northern fence boundary and not in other directions. The accidental releaseidentified in Table 24 on page 94 refers to a specific release which occurred on 11/17/60.Modeling results from chronic and acute releases indicate that concentrations of publichealth concern will not reach off-site locations from smaller releases such as the puffs andjettings which were discussed in the DOE's Phase II Independent Investigation of thePaducah Gaseous Diffusion Plant. However, the quantities of UF6 released during the"midnight negatives" and the frequency of these releases are unknown; therefore, we cannotdetermine the potential for adverse health effects off site from these releases. One of ourconclusions in the PHA reads "Past short-term, or acute air exposures to uranium andhydrogen fluoride are indeterminate, because total release quantities and completed exposure pathways are uncertain."

  1. Page 119, section Polychlorinated Biphenyls, 1st paragraph: "A recent study of more than 7,000 capacitor workers..."
  2. KDEP has several concerns and questions about this study. References to this studyshould be removed from the ATSDR report because the referenced lacks a rigorouspeer review and appears to be inadequate.

    Response: The article in question was published in a scientific, peer-reviewed journal. Aswith all studies, there are some limitations, but it is not because of a lack of peer review or that it is an inadequate study.

  1. Page 119, section Polychlorinated Biphenyls, 2nd paragraph: Based on criteriaestablished by the Food and Drug Administration, the Commonwealth has placed afish consumption advisory on Little Bayou Creek. Therefore, it is irresponsible forATSDR to contradict the necessity for this posting. In addition, KDEP and DOE arecurrently evaluating PCB levels of fish in Bayou Creek and have determined that itsubsequently will also be posted, based on the Great Lakes protocol.
  2. Response: The PGDP Public Health Assessment makes no reference to or statementabout not posting a fish consumption advisory. A fish advisory should be posted as awarning when regulatory standards are exceeded in the fish. However, regulatory standardsare based on worst case scenarios and "no observed adverse effect levels" divided by safetyfactors of 10 or 100, sometimes several times. Our statements are based on our review of thesite specific data, research, and literature, and reflects our best determination whethersomeone who eats fish or deer AT THIS SITE will have adverse health effects from thelevels of consumption.

  1. Page 132, Statistics from Cancer Registries: KDEP believes that ATSDR shouldincrease the time period for the cancer registry. The time period evaluated should be1980 through 1998. KDEP asks ATSDR to include skin and digestive tract cancers.
  2. Response: The Kentucky General Assembly passed Senate Bill 41 in April, 1990, whichestablished the Kentucky Cancer Registry and mandated reporting of all cancer cases inKentucky. Cancer incidence data from the Kentucky Cancer Registry are not available priorto 1991. Estimated cancer incidence rates are available from 1973 through 1989 in theNational Cancer Institute's Cancer Surveillance, Epidemiology, and End Results (SEER)database that are not age-adjusted. Below are the estimated incident rates (not age-adjusted) for bladder cancer from the SEER database for Kentucky, Ballard County, andMcCracken County.

    TABLE J-2:

    ESTIMATED BLADDER CANCER CRUDE INCIDENCE RATES PER 100,000 POPULATION1
      1973 through 1979 1980 through 1989 1973 through 1989
    Kentucky 16.40 19.07 18.00
    Ballard County 15.14 24.06 20.34
    McCracken County 16.90 19.15 18.24
    1 National Cancer Institute's Cancer Surveillance, Epidemiology, & End Results (SEER) database

    In response to KDEP's request, ATSDR reviewed melanoma, esophagus, stomach, liver,pancreas, kidney, and colorectal cancer rates reported by the Kentucky Cancer Registry for the Commonwealth, the Purchase Area Development District, Ballard County andMcCracken County from 1991 through 1999.

    TABLE J-3:

    AGE-ADJUSTED SKIN MELANOMA AND DIGESTIVE TRACT CANCER INCIDENCE RATES PER 100,000 POPULATION1
    (Average Rate for 1991 through 1999)
      Melanoma Esophagus Stomach Liver Pancreas Kidney Colorectal
    Kentucky 18.54 4.27 6.23 2.91 9.14 9.83 61.47
    Purchase Area Development District 19.08 3.12 4.49 1.73 8.33 8.03 54.07
    Ballard County 20.08 0.89 4.33 0.87 9.79 10.92 66.69
    McCracken County 17.22 3.25 4.81 1.46 7.57 6.57 52.62
    1Kentucky Cancer Registry's website http://web.kcr.uky.edu

    ATSDR also reviewed SEER's estimated cancer incidence data for melanoma of the skin and digestive tract cancers for 1973 through 1989 (not age-adjusted).

    TABLE J-4:

    ESTIMATED SKIN MELANOMA AND DIGESTIVE TRACT CANCER CRUDE INCIDENCE RATES PER 100,000 POPULATION1
      Skin Melanoma
    1973-1979
    Skin Melanoma
    1980-1989
    Skin Melanoma
    1973-1989
    Digestive Tract
    1973-1979
    Digestive Tract
    1980-1989
    Digestive Tract
    1973-1989
    Kentucky 7.02 10.99 9.40 78.25 85.48 82.58
    Ballard County 8.41 12.03 10.52 79.04 86.62 83.46
    McCracken County 6.90 10.46 9.03 81.39 89.17 86.03
    1 National Cancer Institute's Cancer Surveillance, Epidemiology, & End Results (SEER) database
  1. Also, how did ATSDR determine the affected population surrounding the PGDPwould be 15 - 90 persons? Please give more details on how this study was conducted.
  2. Response: The potentially affected population surrounding PGDP was determined byoverlaying areas of potential exposure with Census estimates of population. An areaproportional process is used that assumes the population of a Census tract is equallydistributed throughout the tract. Thus, the number of potentially exposed persons isproportional to the percentage of the Census tract that is covered by the exposure area(s).

  1. Page 132, section Environmental Health Survey of Individuals Exposed toContaminated Groundwater, 1st paragraph: Revise the document to denote TCE inparentheses.
  2. Response: We used the title of the referenced document as our section title. Any revision would be inappropriate.

  1. Page 137, section Surface Water and Sediment, 2nd paragraph: The text seems toindicate that Solid Waste Management Units (SWMUs) and landfills areinterchangeable terms. However, landfills are only an example of a SWMU at the site.There are various other types of units (i.e., storage yards, ditches, etc.) That are alsoSWMUs. Please clarify the report to indicate this.
  2. Response: Reference to solid waste management units has been deleted in this sentence.

  1. Page 141, Question 1: "These signs list the types of fish..." This is an inaccurate statement. The postings on Little Bayou Creek do not list types of fish that can safely be consumed.
  2. Response: This comment references a response to a citizen concern: "She knew about thesigns that posted mercury warnings for bass, but did not understand why some fish wereposted while others were not." The accurate quote from ATSDR's response in the PHAreads "These signs list the types of fish because these fish have been found to containchemicals that can harm you if you eat them in large amounts. (Because different fish have different food sources they ingest and retain different concentrations of contaminants.)"

  1. Page 142, Question 1: "However, occasionally eating other fish from this area (theposted areas) will not cause harm because they do not contain enough chemicals tomake you sick. Also, if you eat turtles...remove the fat...." Why does ATSDR in anyway indicate that eating fish or turtles from Little Bayou Creek is either acceptableor safe?
  2. Response: Please read the concern on page 139. Our response was for these concernedpersons who occasionally fish in ponds at the WKWMA and occasionally eat turtles caughtat the WKWMA. No one we observed or talked with tries to fish in Little Bayou Creek.

  1. Page 144, Question 2: Has ATSDR completed an evaluation of residents downstreamof the PGDP on the Ohio River? If so, please provide the results. If not, what is theabove supposition based on?
  2. Response: Our response was "Residents downstream on the Ohio River from the PGDPshould not have been adversely affected by PGDP." This statement was based on current andhistorical environmental monitoring data including analyses of water samples taken from the Ohio River.

  1. Page 145, Question 5: In response to a question about the number of birth defects caused by contamination      Answer: "None...."
    Does ATSDR have information that supports this conclusion? If so, the information should be provided in a revised report. If not, the report should be revised to clearly indicate the basis for this conclusion.
  2. Response: The response to question 5 has been expanded and the references have been included.

  1. Page 156, Recommendation Number 4: "...disconnecting water pipes to homes ... andplugging or dismantling the wells."Does this include only disconnecting water pipescoming from the wells? Also, dismantling of all wells may not be appropriate asseveral of these wells are effective groundwater monitoring points.
  2. Response: The idea is to prevent the use of the wells for drinking water and to prevent thepotential spread of contaminants. Disconnecting the water pipes to the home does not preventthe well owner from using the well to water his garden or crops, etc.

  1. Appendix C: No slope factors were included in text or tables. Without slope factors,risk calculations cannot be duplicated and/or verified. There should be a table thatincludes all reference doses and slope factors.
  2. Response: The reference for EPA's Cancer Slope Factors (EPA's Integrated RiskInformation System) has been added to Appendix C.

  1. Page C-4, Table:
    "No increased risk = Less than 1 per 100,000 (<1.0E-05)
    No apparent increased risk = 1 per 100,000 (1.0E-05)"
    In Kentucky, the point of departure for risk is 1 per 1,000,000 (1.0E-06). Risk that iscalculated between 1.0E-06 and 1.0E-04 will require some type of risk management.For risk that is above 1.0E-04, removal or remediation will be required.
  2. Response: ATSDR acknowledges the comment and understands that the State uses EPA'sRisk Assessment paradigm. ATSDR's Public Health Assessment is not a risk managementdocument but assesses the likelihood of adverse public health effects.


Page C-5, Table C-1:

Here are comparisons of some KDEP and ATSDR values which are at variance.
Exposure Factors for WKWMA Workers
PATHWAY ATSDR KDEP(USEPA 1994)
Soil
Exposure Frequency 1.5 days/week 3 days/week
Incidental Ingestion 200 mg/day 480 mg/day
Exposure Factors for Off-Site Resident (Recreational)
PATHWAY ATSDR KDEP(USEPA 1994)
Surface Water
Exposure Frequency 12 days/year 45 days/year
Soil
Ingestion (Adult) 50 mg/day 100 mg/day
     Sediment    
     Exposure Frequency 12 days/year 104 days/year

Response: The exposure scenarios used in the PGDP Public Health Assessment reflect realistic and health-protective exposure conditions for the community near the PGDP site. The USEPA values are not site specific.

  1. Page H-2, 1st paragraph: "Chromium particles in the cooling tower drift havediameters of 5 to 50 microns." KDEP believes that ATSDR has incorrectly calculatedthe diameter of chromium particles (chromate ions). Based on KDEP calculations thediameters should be 0.4 nm or 0.0004 m.
  2. Page H-2, 1st paragraph: "...These particles are contained within water droplets thathave diameters of 100 to 1,300 microns." KDEP believes that ATSDR has incorrectdiameters of water droplet particles. The particles from the tower are probably 10-40m. In a cloud the droplets will be in the 20 to 100 m range. At 200 m the particlewill fall as rain.

    Response: The stated particle dimensions are based on information contained in thereferenced documents listed in the PHA. As stated, the significant particle dimensions arethose of water particles containing chromium. As the results of the dispersion model areconsistent with field measurements, the assumptions underlying the model appear to beappropriate. However, if KDEP provides specific references or data contradicting thesereports, ATSDR will determine whether those data warrant a re-evaluation of the dispersion of airborne chromium.

  1. This document concludes that there has not been or currently are any conditions thatwould lead to adverse health effects for people living near PGDP. In reality, thereport only indicates that based on recent and current data, there might be a smallamount of risk to the public from current environmental conditions. However, dataindicates that historical releases have occurred from the plant. This study did notadequately evaluate historical data and therefore did not address the potential healthimpacts that may have incurred during the earlier years of operation at the PGDP.As a result, it does not seem appropriate to conclude that only (2) exposures (aspresented on Page 154, Conclusion No. 2) have occurred in the past at this site.KDEP requests that ATSDR address all above concerns and clarify why significantamounts of historical data were not used to evaluate public health concerns in thisstudy.
  2. Response: These statements are an erroneous interpretation of our conclusions. ATSDR hasclearly identified several contaminants and conditions that could have created adverse healtheffects. The PHA's conclusions are based on extensive review and evaluation of historicaldata, which are referenced throughout the document.

  1. Page 41 of the report is incorrect about there being no ambient SO2 monitoringhaving been conducted near the PGDP site. The Kentucky Division for Air Qualityoperated an ambient SO2 monitor north of PGDP at the West Kentucky WildlifeManagement kennels from approximately 1975 until the year 2000. Data is availablefrom the Division.
  2. Response: ATSDR has requested relevant environmental data from the Kentucky Divisionof Air Quality (KDAQ) on several occasions beginning with our visit to their district officein May 1996. If such data exists, they have not made it available to ATSDR. Consequently,we have relied on emission and dispersion modeling to provide the information necessary forthis PHA. If KDAQ has SO2 data indicating potential exposures of community health concern, ATSDR believes it is incumbent on that agency to provide and evaluate that data.

    1. The contribution of airborne radionuclide, hydrogen fluoride, hydrochloricacid, arsenic, and heavy metal emissions including chromium from boilerswere not addressed.

    2. Airborne arsenic emissions were not addressed in the report. Airborne arsenicemissions occur from the C-310 cascade stack and the boilers.

    Response: Fossil fuel combustion presents the potential for release of the abovecontaminants; however, PGDP's steam plant (coal and fuel oil boilers) is not a significantsource. Using standard emission factors for arsenic and chromium from coal combustion[15] and the maximum rated capacity of the coal boiler [16] results in estimated maximumstack release rates of 0.01 g/sec for arsenic and 0.02 g/sec for chromium. Emission factorsfrom the oil boiler are less than 1% of the coal boiler. Emission at these release rates from110-foot stacks does not result in a significant environmental concentration of either arsenicor chromium. We have no information on the amount of arsenic released from the C-310stack. Emissions of radionuclides from the steam plant represent an insignificant sourcerelative to the uranium process emissions, and emissions of heavy metals are insignificant relative to the smelter emissions.

  1. January 20, 1991 and October 27, 1990 airborne HF emissions that exceeded state standards were not addressed.
  2. Response: Short term exceedances of a regulatory emission standard does not necessarilyindicate a release of public health concern. These short term exceedances were much lessthan the accidental releases that were discussed in the PHA. We will refer this comment to the Kentucky Division of Air Quality for their comment.

  1. Questions about the ambient radionuclide monitoring by the Kentucky Departmentof Health's Radiation Control Program are under review by the Kentucky Divisionfor Air Quality. A problem with location of a monitoring site was identified. Monitorsite maintenance problems have been identified. Questions on sample analysis, qualitycontrol and quality assurance have not been resolved.
  2. The health conclusions related to airborne radionuclide concentrations off site are based onseveral sources of information in addition to data from the KRCP. We are aware of someproblems with these air monitors including vandalism. If the KDAQ review establishessignificant errors in the air monitoring data, ATSDR will re-evaluate the monitoring data if revisions to the data would indicate potential public health concern.

  1. Air emissions of beryllium from historic operations in the C-720 shop area were not addressed. See December 2000 USDOE "Report on the Paducah Gaseous DiffusionPlant, Metals Recovery Program".
  2. Response: Beryllium metals and beryllium-copper alloys were machined in Building C-720in 1965. Since there is not enough information on the amount of beryllium potentiallyreleased, air emission and dispersion calculations from this building were not possible.ATSDR reviewed the soil, sediment, surface water, and biota/food environmental samplingdata for concentrations of beryllium. These data indicate that beryllium is not a contaminant of concern off site.

    1. Historical airborne emissions from the smelting and casting of nearly 20million pounds of radiological contaminated nickel at C-746A were notaddressed. See December 2000 USDOE "Report on the Paducah GaseousDiffusion Plant, Metals Recovery Program".
    2. Airborne emissions from the 1970 to 1986 smelting and casting ofapproximately 4.5 million pounds of radiological contaminated aluminum inC-746A were not addressed. See December 2000 USDOE "Report on thePaducah Gaseous Diffusion Plant, Metals Recovery Program".
    3. Historical airborne emissions of cobalt from the C-746A smelting operationswere not addressed. See December 2000 USDOE "Report on the PaducahGaseous Diffusion Plant, Metals Recovery Program".
    4. Airborne lead emissions from shedding and smelting of more than one millionpounds of lead at PGDP were not addressed. See USDOE December 2000,"Report on the Paducah Gaseous Diffusion Plant "Work for Others"Program including Weapons Support and Disposition."

    Response: Refer to ATSDR's Health Consultation, "Exposure Assessment of AirborneNickel and other Metal Particulates from Historic Smelter Operations at the PaducahGaseous Diffusion Plant," which has been added as an appendix to this document.

  1. A C-310 stack release of uranium on October 17, 1989 resulted in an off siteexposure of 0.48 ng/m3 of uranium. No mention of this release was found in thereport. (See November 27, 1989 letter from USDOE to Kentucky Division of AirQuality.)
  2. Response: The most of this release occurred on October 13, 1989; however, the problem wasnot completely solved until October 17, 1989. No mention of this release was made in thePHA, because the quantity released was substantially smaller than the quantities releasedduring the accidents that were discussed. (On October 13, 1989 between 128.84 grams and175,68 grams of uranium enriched up to 1.896% uranium 235 were released. During the1960 accident 8,074 kilograms of UF6 were released, and during the 1962 accident 2,296kilograms of UF6 were released.) For an airborne concentration of 0.48 ng/m3of uranium, thepotential exposure to an individual would be less than 0.0001 mSv (or 0.01 mrem) andwould have no adverse health effect.

  1. Airborne asbestos emissions from the PGDP were not addressed in the report. Large amounts of asbestos are present at the plant. Asbestos removal has been occurringfor years at the plant.
  2. Response: Historically, asbestos was used at PGDP as insulation of the process componentsand in buildings. If the buildings are not disturbed, elevated levels should not be seen in theenvironment. The levels can be above average near buildings that contain asbestos and arebeing torn down or renovated or near waste sites where asbestos is not properly covered orstored to protect it from wind erosion [17]. In these cases people who work with the asbestosor the asbestos-containing products without proper protection are of greatest concern. Thereare no residences close to the on-site buildings that have been torn down or renovated or nearwaste sites where asbestos products may have been disposed. Therefore, ATSDR does notbelieve that asbestos is an off-site airborne contaminant of concern at this site.

    1. Page 161, #4: Did this report contain calculations of radiation doses to off-site populations?
    2. Response: This report listed all the input parameters for the calculations and givesthe effective dose equivalent for the maximally exposed individual; however, theactual calculations are not presented.

    1. Page 170, #70: Did this report contain calculations of radiation doses to off-site populations?
    2. Response: No.

  1. For the air release at 4:00 am on November 17,1960, were farmers, deer hunters, shift workers or school children outdoors during the incident?
  2. Response: The incident occurred at a time when it is not likely that hunters, farmers, orschool children would be outdoors; however, ATSDR concluded that short-term (acute)historical air exposures were indeterminate, because the total release quantities andcompleted exposure pathways are uncertain.

  1. What is the water tower northeast of the plant? Is the water coming from a well?
  2. Response: The water tower is used to store municipal water purchased from the City of Paducah. This water originally comes from the Ohio River.


Peer Review for the Paducah Gaseous Diffusion Plant (U.S.DOE) Public Health Assessment

Professionals outside of ATSDR performed a peer review of the Paducah Gaseous Diffusion PlantPublic Health Assessment. The panel members were given copies of the Public Comment Release ofthe Paducah Gaseous Diffusion Plant Public Health Assessment. Following their review, theysubmitted written comments to ATSDR. Changes have been made to the public health assessmentbased on their comments. Primarily, the comments concerned 1) how different aspects of the publichealth assessment were described, 2) if environmental/toxicological data and models were usedappropriately, 3) if the potential health threat posed by the site was communicated accurately andclearly, and 4) if the conclusions and recommendations are appropriate for the site conditiondescribed in the report. Their comments are included, along with our responses in the followingtable. No changes were made to the conclusions or recommendations based on the reviewers'comments.

Peer Review for Paducah Gaseous Diffusion Plant (U.S. DOE)
Paducah, McCracken County, Kentucky
Question/Peer Review Comment Agency Response to Comment
1. How well does the public health assessment describe the nature and extent of contamination?
The PHA describes the nature of the contamination very well as it relates to the existing databases and other documentation.
The extent of the contamination is likely over estimated when data gaps exist and mathematical models were used to predict concentrations at distances from the site. When using these models, very conservative assumptions were made for parameters that were not accurately known. These conservative assumptions produced results that tend to over predict the distance contaminates traveled off site thereby increasing the size of potential exposed-population. This resulted in assessments that were very protective of the public, i.e., it is likely that subpopulations were included that may not have been measurably exposed.
Thank you.

An ATSDR public health assessment is an analysis of the public health implications posed by a site to determine whether more extensive public health actions or studies are needed. When possible, we use site specific information; however, if data gaps exist, we use conservative assumptions when making these determinations.

The nature and extent of the contamination appear to be fully and well characterized, despite gaps in the available data. Thank you.
My review of this public health assessment of the PGDP indicates that it was carefully researched, generally well written and that it provides a good description of relevant factors that impact the nature and extent of contamination involved. This document further carefully considers virtually all possible scenarios that may lead to contamination in the future. Thank you.
2. How well does the public health assessment describe the pathways of potential human exposure and delineate the exposure doses via those pathways?
If any doubt, the pathway was assumed to be present (complete). The practice resulted in an increased exposed population and types of exposed populations, e.g., children. In addition, this practice increased the number of contaminants that could result in contaminate doses. This resulted in assessments that were very protective of the public, i.e., it is likely that subpopulations were included that may not have experienced detectable doses or medically effective doses. As stated above in response to question #1, we use site specific information if possible; however, if there is a doubt, we make health-protective assumptions to determine if further public health actions or studies are indicated..
The general characterization of pathways of potential human exposure is well done, and the Introduction to the topic of pathways and pathway analysis on pp.11 is particularly good. Thank you.
This document describes in considerable detail all the possible pathways of potential human exposure that I can recall and some I had not thought of. It is also obvious that considerable effort was exerted to delineate exposure doses via each of those pathways. In my opinion, some estimates of exposure are somewhat conservative, i.e., overly protective of the exposed population, but I concede that it is certainly better to err on the conservative side of the equation. Thank you.
3. How well does the public health assessment describe expected human exposure levels relative to the short- and long-term health effects associated with identified hazardous substances?
Very well. Thank you.
Potential health effects from anticipated exposure levels to hazardous substances appear to be accurately characterized and well justified with appropriate citations from the relevant scientific literature.

An exception relates to uranium, which when inhaled as an insoluble particulate may present a greater hazard from its radioactivity than its chemical toxicity. This point is not made in the body of the report, and needs to be considered, especially with respect to the 1960 accidental release, even though it will likely not alter the results of the assessment or the conclusions.

Generally, where specific scientific data germane to the determination of a reasonably potential health effect is lacking, related data are considered and evaluated in a manner that appears to be fully consistent with assurance that public health criteria will be met. Although specific primary sources are not always cited, the use and citation of secondary sources such as the generally excellent ATSDR Toxicological Profiles is considered to be preferable, offering to members of the potentially affected cohort as well as the general public and health practitioners who wish a more in depth examination of a particular topic a convenient summary document that cites the primary sources in greater depth than would be practicable in a public health assessment of this nature.

Thank you.

Uranium, as an inhaled insoluble particulate was discussed in the health implications for Radioactive Materials; however, this was not noted under the section "Uranium" which was written for the chemical toxicity. The 1960 incident was also discussed in the radioactive material section. We will clarify this in the final report and make any necessary corrections in the body of the report.

Thank you.

This document clearly describes conditions in the area and explains in considerable detail how existing safety measures, prevailing wind direction and ground water contamination levels impact human exposure. It also points out that provision of municipal water supplies and other precautions taken limit anticipated human exposure. The document goes on to describe how, given these factors, it is unlikely that people in the area will be exposed to levels of hazardous agents that would have short- or long-term adverse effects. Thank you.
4. How well does the public health assessment describe potential health effects and existing morbidity and mortality data on diseases that may be associated with observed levels of exposure?
Well, at least to the extent the databases could be used in the analyses. Thank you.
The ATSDR conclusions regarding potential health effects are clearly described, and generally well developed and justified. The sections on specific substances, while brief, adequately characterize potential health effect and are generally well written, clear and concise. Thank you.
This subject was addressed to the extent possible, and no obvious adverse effects on the health of those living in the area were observed. However, as explained in the document, the low population of the area in question limits the statistical power of any assessment of morbidity and mortality. Thank you.
5. Are the environmental and toxicological data and models being appropriately used to assess potential environmental contaminants and exposure doses?
In the sense that they tend to be used conservatively, i.e., very protective of the public, resulting in increased number of contaminates and increased predicted dose levels to be addressed for larger population sizes. Thank you.
Standard and accepted models are used in conjunction with appropriate toxicological and related data to provide a reasoned and reasonable predictive assessment of both potential environmental contaminants, exposures and doses. There is nothing in the report to suggest that these assessments are in any way wanting. Thank you.
The environmental and toxicological data reviewed and the models used to assess potential possible adverse health effects of the potential environmental contaminants are quite adequate. Further, the application of these models to calculate current and potential exposure doses are adequate and, if anything, conservative. Thank you.
6. Does the public health assessment accurately and clearly communicate the health threat posed by the site?
Yes, I believe it does. However, there is a lot to understand. The important audience for this PHA is the general public near the Paducah Gaseous Diffusion Plant. I know that it took me many hours to read the PHA from cover to cover. I doubt many members of the general public near the plant will be that committed to reading a highly technical report. The Executive Summary is only 4 pages, but the reader must accept on faith the conclusions; of course, this is the nature of an executive summary. This is a public communication problem for studies of this type. Recommend exploring other means of communicating the PHA results to the immediate public near the plant. For example, I'm sure that ATSDR will have a series of public meetings near the plant subsequent to the release of the PHA. ATSDR issued a fact sheet to the public at the time of the draft public health assessment release. On May 1, 2001, ATSDR held a public meeting at a location near the site to address this public health assessment and questions from attendees. ATSDR staff has also talked to some community members by telephone since then. We are pursuing the possibility of conducting health education activities in areas where the community members still have questions and concerns, if the community is interested.
Yes; there appear to be no omissions or misuse of data, and the conclusions are logically developed and well supported with data. The recommendations are reasonable and practical and fully consistent with both the past and continuing public health assessment and surveillance of the site. Thank you.
My review of this public health assessment indicates that it is very thorough and accurately prepared. Further, it clearly communicates possible adverse health threats posed by possible contamination resulting from this site. Thank you.
7. Are the conclusions and recommendations appropriate in view of the site's condition as described in the public health assessment?
Very much so. ATSDR used a very conservative and public protective approach to performing this PHA. In this case, substantial exposure, doses, and/or outcomes resulting in adverse effects were not documented. The public near the plant, with little reservation, should accept the conclusions and recommendations of this PHA if properly communicated. Thank you.
Yes. See also Item 6, supra. The recommendations for future surveillance are quite well reasoned and incorporate sufficient breadth and conservatism to provide assurance that any possible or potential future untoward public health problems from this site will be detected in sufficient time to effect remedial measures to obviate potential health effects. Thank you.
Based on my review of this document and my more than 30 years of experience in the field of environmental toxicology, it is my opinion that the conclusions and recommendations made herein represent an appropriate assessment of the site's condition and resulting risks to public health. Thank you.
8. Are there any other comments about the public health assessment that you would like to make?
Editorial and other comments are identified by red page markers in the body of the reviewed PHA. Thank you for your detailed comments on this document. They will be addressed in the final version.
Although this is a particularly well prepared document that is generally easily read, some minor improvements are indicated, particularly in the Glossary. Some specific comments in this regard follow. The definition of Committed Effective Dose is inconsistent with the definitions for the units rem and sievert, and the symbol for sievert is not given in the definition. Although the term effective dose is used in the body of the report, it is not defined per se in the Glossary, although the term committed effective dose, a rather different quantity, is. The definition of Contaminant is wanting and grammatically incorrect. The term exposure dose is used in conjunction with exposure to radioactivity. This is an inappropriate term and is not defined in the Glossary. The term was at one time used in health physics but was made obsolete decades ago. It is suggested that the term radiation dose be substituted. Clarifications, corrections, and appropriate additions will be made to the Glossary.
Finally, as a very minor and perhaps indeed trivial comment, it was noted that in the section on Specific Substances under the broader chapter entitled "Public Health Implications" there is inconsistency in the characterization of the specific contaminants, viz. identification of some metals as such, others as elements, and uranium specifically as a radioactive metal. This was likely done for stylistic reasons, but it might be appropriate to identify metals as such in all cases to avoid any confusion with nonmetallic elements or chemical compounds. We will make the terms consistent, but it will necessitate changes to other sections as well.
No. Thank you.

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