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PUBLIC HEALTH ASSESSMENT

WELDON SPRING SITE REMEDIAL ACTION PROJECT
(CHEMICAL PLANT, RAFFINATE PITS, QUARRY)
ST. CHARLES, ST. CHARLES COUNTY, MISSOURI


APPENDIX D: GLOSSARY

Ci A curie (Ci) is the basic unit used to describe the intensity of radioactivity in a sample ofmaterial. The curie is equal to 37 billion disintegrations per second, which is approximately therate of decay of 1 gram of radium.
CREG Cancer Risk Evaluation Guides (CREGs) are the estimated contaminant concentrationsthat would result in one excess cancer in a population of a million persons exposed over alifetime (70 years). CREGs are calculated from the U.S. Environmental Protection Agency's(EPA's) cancer slope factors.
Effective Dose The sum of the products of the dose equivalent to the organ or tissue and theweighing factors applicable to each of the body organs or tissues that are irradiated.
EMEG Environmental Media Evaluation Guides (EMEGs) are values used to select chemicalcontaminants of potential health concern. The Agency for Toxic Substances and Disease Registrycalculates EMEG values using conservative exposure assumptions designed to protect the mostsensitive segment of the population.
Gy Gray (Gy) is the unit of absorbed dose (1 Gy = 100 radiation absorbed dose [rad] units)developed by the International System (SI) of weights and measures.
Ionization Ionization is the process of adding one or more electrons to or removing one or moreelectrons from atoms or molecules, thereby creating ions. High temperatures, electricaldischarges, or nuclear radiations can cause ionizations.
MCL Maximum Contaminant Levels (MCLs) are contaminant concentrations that EPA deemsprotective of public health over a lifetime (70 years) at an exposure rate of 2 liters of water perday.
mrem Millirem, or one-thousandth part of a Roentgen equivalent man (rem) unit.
mg/kg Milligrams per kilogram, equivalent to parts per million (see below).
mSv Millisievert, or one-thousandth part of a sievert.
µg/m3 Microgram per cubic meter.
µCi Microcurie. A microcurie is equivalent to one-thousandth of a curie
pica An abnormal craving to eat substances not fit for food, as clay or paint.
pCi Picocurie (pCi) is equivalent to one trillionth part of a curie.
Progeny Progeny refers to isotopes formed by the radioactive decay of some other isotope.
R Roentgens (R) are units used to measure exposure to ionizing radiation. A roentgen is theamount of gamma rays or X rays required to produce ions carrying one electrostatic unit ofelectrical charge in one cubic centimeter of dry air under standard conditions.
rad Radiation absorbed dose (rad) is a unit used to measure how much radiation an object absorbs after it is exposed to radiation.
rem Roentgen equivalent man (rem) is a unit used to measure the radiation effectiveness inman. It is a function of the radiation absorbed dose (rad) and the type or quality of radiation.
RfD Reference doses (RfDs) are estimates of the daily exposure to a contaminant unlikely to cause adverse health effects.
RMEG Reference Dose-based Media Evaluation Guide (RMEGs) are values calculated using EPA's Reference Dose (RfD) (see definition above).
Sv Sievert (Sv) is the SI unit of radiation effectiveness in man. The dose equivalent in sieverts is equal to the absorbed dose in gray multiplied by the quality factor (1 Sv = 100 rem).


APPENDIX E: ATSDR DOCUMENTS

PRELIMINARY PUBLIC HEALTH ASSESSMENT

Addendum to Preliminary Public Health Assessment

April 24, 1989, Health Consultation

February 10, 1993, Health Consultation

1993 Letter on Proposed Cleanup Levels

January 20, 1994, Health Consultation

August 30, 1994, Health Consultation


PRELIMINARY PUBLIC HEALTH ASSESSMENT

WELDON SPRINGS SITE

ST. CHARLES, MISSOURI

CERCLIS NO.'S
M05210021288

DECEMBER 15, 1988

*AMENDED*

M03210090004 (DOE)
M05210021288 (DOD)

THE ATSDR HEALTH ASSESSMENT: A NOTE OF EXPLANATION

Section 104 (i) (7) (A) of the Comprehensive Environmental Response, Compensation, andLiability Act of 1980 (CERCLA), as amended, states "...the term 'health assessment' shall includepreliminary assessments of potential risks to human health posed by individual sites andfacilities, based on such factors as the nature and extent of contamination, the existence ofpotential pathways of human exposure (including ground or surface water contamination, airemissions, and food chain contamination), the size and potential susceptibility of the communitywithin the likely pathways of exposure, the comparison of expected human exposure levels to theshort-term and long-term health effects associated with identified hazardous substances and anyavailable recommended exposure or tolerance limits for such hazardous substances, and thecomparison of existing morbidity and mortality data on diseases that may be associated with theobserved levels of exposure. The Administrator of ATSDR shall use appropriate data, risksassessments, risk evaluations and studies available from the Administrator of EPA."

In accordance with the CERCLA section cited, ATSDR has conducted this preliminary healthassessment of the data in the site summary form. Additional health assessments may beconducted for this site as more information becomes available to ATSDR.

The conclusion and recommendations presented in this Health Assessment are the result of sitespecific analyses and are not to be cited or quoted for other evaluations or Health Assessments.

PRELIMINARY HEALTH ASSESSMENT

WELDON SPRING QUARRY

WELDON SPRING, MISSOURI

NOVEMBER 18, 1988

Prepared by:
Office of Health Assessment
Agency for Toxic Substances and Disease Registry (ATSDR)

Background

The Weldon Spring Site (WS) is listed by the U.S. Environmental Protection Agency on theNational Priorities List (NPL). The 9-acre site is an abandoned limestone quarry located in Weldon Spring (St. Charles County),Missouri. WS contains approximately 95,000 cubic yards of radiological and chemicallycontaminated soil, rubble, debris, and equipment. Part of WS, the training area, is controlled bythe U.S. Department of Defense (e.g., U.S. Army). The other portion of WS is under control ofthe U.S. Department of Energy. The site boundaries will be expanded to include the chemicalplant and raffinate pits as part of the existing NPL site. The chemical plant was a formerordnance production facility in the late 1940's, and was used for uranium processing in the late1960's. The raffinate pits are unlined areas used for the disposal of wastes from the production ofpure uranium. These pits have been reported to contain silica, uranium, and thorium. Access tothe site is restricted. Removal actions have not occurred.

The following documents were reviewed by ATSDR: (1) Radiological Report, September 1985,(2) Research Investigation of Hazardous Waste, February 1987, (3) Chemical CharacterizationReport, August 1987, (4) Hydrology and Water Quality Report, December 1987, (5) Water Quality PhaseI Assessment, December 1987. These documents form the basis of this Preliminary HealthAssessment.

Environmental Contamination and Physical Hazards

Preliminary on-site soil sampling results have identified radium-226 (1,200 pCi/g), thorium-230 (6,800 pCi/g), uranium (2,400 pCi/g and 8,350 ppm),2,4,6 trinitrotoluene TNT) (1,600 ppm), 2,4 dinitrotoluene (DNT) (33 ppm), 2,6 DNT (68 ppm), polynuclear aromatichydrocarbons (PAHs) (1,000 ppm), polychlorinated byphenyls (PCB's 120 ppm). In addition,uranium was identified in groundwater (8,800 pCi/L) and surface water (2,100 pCi/L).

Preliminary off-site groundwater sampling results have identified uranium (4,692 pCi/L); 2,4,6,TNT (15 to 377 ppb); 2,4 DNT (0.5 ppb); 2,6 DNT (3 ppb), and 1,3,5 trinitrobenzene (TNB) (7 ppb). In addition, uranium was detected in surface water (116 pCi/L). Physical hazards were not reported.

Potential Environmental and Human Exposure Pathways

Potential environmental pathways include contaminated groundwater, surface water, soil andsediment, and volatilization of contaminants or contaminants entrained in ambient air. Inaddition, bioaccumulation of contaminants in fish, water fowl, livestock, and commercialagricultural products may be another environmental pathway.

Potential human exposures to contaminants include ingestion of and direct contact withgroundwater, surface water, soil, and possible ingestion of bioaccumulated contaminants in thefood chain. In addition, inhalation of volatilized contaminants or contaminants entrained in air isanother potential source for human exposure.

Demographics

It is unknown as to how many people live within a 2-mile radius of the site. The distance fromWS to the nearest residence has been estimated to be less than 2 miles. The well field, a watersource for 58,000 people, is less than a mile from WS. A high school is located approximately 3miles from the quarry.

Evaluation and Discussion

Soil surface contamination by explosives and groundwater contamination from the quarry areextensive. There are reportedly areas of radioactive contamination in the army training area. On-site, soil concentrations of Ra-226 exceeds the limits expressed in 40 CFR 192 for uranium by-products by a factor of approximately 1,000. In addition, Radon-222 emanating from this site isassumed to exceed these limits (20 pCi/m2 per second). It is unclear if the Army currentlyconducts training on-site. Direct contact and possibly inhalation of potentially hazardousmaterials poses an imminent public health concern to soldiers training on-site. The U.S.Department of Energy (DOE) intends to collect waste materials currently in the Army trainingarea. Moreover, DOE intends to deposit the waste materials with the other radioactive wastecurrently present in the raffinate pits and quarry area.

Soil sampling information confirms the presence of site-related contaminants off-site. Off-sitecontamination reportedly is not extensive, but off-site soil sampling information was notreported. Off-site soil sampling information is necessary to determine the extent of exposure ofsite-related contaminants to area residents. It was reported that on-site exposure is unlikely sincethe area is fenced. It was also reported that air sampling measurements were performed on-site,but air sampling information was not reported. Entrainment of contaminants in airborne dust maybe a possible exposure pathway to area residents as well as persons having authorized access tothe site.

Private wells in use within several miles of the site are not reported to be contaminated. Theprivate wells in the vicinity of WS are reported to be in "a separate hydrogeological system".Sampling information confirming the absence of site-related contaminants in area private wellswas not reported. Various site-related contaminants (TNT, DNT, TNB, and uranium) wereidentified in off-site groundwater and there have been unsubstantiated reports that the aquifer ofconcern may be fractured. Therefore, sampling of area private wells is necessary to rule outexposure and possible health concerns to area residents. Production wells are not contaminated.However, sampling information confirming the absence of site-related contaminants has not beensupported. Municipal wells within the vicinity of WS are not contaminated. Public system datahave confirmed the absence of site-related contaminants in municipal well water.

A small stream adjacent to WS is reported to be contaminated. The stream flows less than 1 mileto the Missouri River. It has been reported that contamination is migrating downstream to theMissouri, "but probably not migrating in large enough concentrations to impact the quality of theriver." Surface water uranium concentrations do not exceed 10 CFR 20 values for the maximumconcentration above natural background for the general public. However, surface water valuesare about twice that normally found in fresh water (usually no more than 70 pCi/L). Sedimentsampling information was not reported and is necessary to define the extent of off-sitecontamination. Moreover, fishing occurs in the adjacent stream and in the Missouri River. Fishflesh sampling (e.g., edible portions) information is also needed to determine the amount ofpossible exposure to area residents. In addition, hunting occurs in the area and it is reported thatdeer, pheasant, water fowl, and rabbits are likely to be contaminated. Biota samples have beentaken but the sampling results are not currently available.

Conclusions and Recommendations

Based on available information, this site is considered to be of public health concern because ofthe risk to human health caused by the likelihood of human exposure to hazardous substances.On-site exposure to gamma radiation poses a significant public health risk to persons havingaccess to the site. In addition, areas directly adjacent to the site may pose serious public healthconcerns because of ingestion of levels of radium in either surface or groundwater. Direct contactwith and incidental ingestion of contaminated soil by authorized personnel and area residents arethe exposure pathways of concern. Other probable exposure pathways include inhalation ofcontaminants entrained in air, ingestion of bioaccumulated contaminants in the food chain, anddirect contact, ingestion with, and inhalation of off-site soil and sediment. Ingestion ofgroundwater may also be another possible exposure pathway.

Additional information on contaminants released, populations potentially exposed, andenvironmental pathways through which the contaminants can reach these populations isnecessary. At a minimum, future investigations of this site should include a characterization ofthe site and site contaminants to include air sampling measurements, area food chain sampling,and off-site soil and sediment sampling, an updated area well survey, and a characterization ofthe hydrogeology of the area.

Further environmental characterization and sampling of the site and impacted off-site areasduring the Remedial Investigation and Feasibility Study (RI/FS) should be designed to addressthe environmental and human exposure pathways discussed above. When additional informationand data such as the completed RI/FS are available, such material will form the basis for furtherassessment by ATSDR as warranted by site-specific public health issues.


March 29, 1990

Environmental Health Scientist, Emergency Response and Consultation Branch (ERCB),Division of Health Assessment and Consultation, ATSDR (E32)

Addendum to Preliminary Public Health Assessment:

    Weldon Spring Chemical Plant,
    Weldon Spring, St. Charles County,
    Missouri
    CERCLIS NO. M03210090004

David A. Parker
ATSDR Regional Services, Region VII
Through: Chief, ERCB, DHAC, ATSDR (E32) ___
         Chief, RPB, DHAC, ATSDR (E32) ___

Attached is an Addendum to the Weldon Spring Health Assessment. This should satisfy yourrequest for consultation for the above mentioned site.

Please contact me if you have any questions regarding this Addendum.

    John E. Abraham Ph.D., M.P.H.

ATSDR:DHAC:ERCB:JEABRAHAM:veb:2/29/90:ext. 0615
Doc. WELDON


The Weldon Spring Chemical Plant Site

Weldon Spring, St. Charles County, Missouri

BACKGROUND AND STATEMENT OF ISSUES

The Weldon Spring Chemical Plant Site is listed by the U.S. Environmental Protection Agency(EPA) on the National Priorities List (NPL). The 17,000-acre site is located in Weldon Spring(St. Charles County), Missouri. A portion of the site, 1,700 acres, has been designated a trainingarea for troops in the U.S. Army Reserve. "Approximately 1 year ago, partially in response toATSDR's and EPA's expression of concern regarding troop training activities in potentiallycontaminated areas, the Army closed the Weldon Spring Training Area to troop training."

The ATSDR received a request on March 2, 1990 (through Mr. David Parker, ATSDR RegionalRepresentative) from EPA Region VIII Superfund Remedial Branch regarding the resumption oftraining of U.S. Army Reserve troops on-site. The EPA would like ATSDR to address whether ahealth threat exists from exposure to lead and trinitrotoluene (TNT), and its related compoundson-site to Army Reservists training in the designated on-site areas.

DOCUMENTS REVIEWED

  1. Preliminary Health Assessment, Weldon Spring Quarry, ATSDR, March 30, 1989.
  2. Memorandum to Mr. Gregory McCabe, WSTM/SPFD/PREP, EPA Region VII from Mr. Edward J. Skowronski, ATSDR Regional Representative, EPA Region VII, Re: Health Consultation for the Weldon Spring Training Area, Weldon Spring, Missouri, August 5, 1988.
  3. Report, IT Corporation, Chicago Illinois. Project No. 312052, Re: Addendum to Draft Remedial Investigation, Weldon Spring Training Area, October 1989.
  4. Memorandum to Commander, U.S. Army Engineer Center and Fort Leonard Wood, ATTN: ATZT-DEH-EE/Scott Murrell, Fort Leonard Wood, Missouri from CEMARK-ED-TD, Re: Identification of Areas to be Re-opened for Training at the Weldon Spring Training Area, January 5, 1990.
  5. Memorandum, to Mr. David Parker, ATSDR Regional Representative, EPA Region VII, fromMr. Greg McCabe, Weldon Spring Ordnance Works Remedial Project Manager, EPA RegionVII, Re: Reopening of Weldon Spring Training Area to Troops, no date given.

DISCUSSION

The designed training areas in question are located outside TNT production areas; moreover,based on historical use, these areas have a low probability for contamination. The Army hasperformed lead and TNT soil sampling within the proposed training area. A subset -- 99 samples-- of the 1,070 soil samples that were considered to be the "most highly contaminated samples"were analyzed (personal communication March 15, 1990, between Dr. Abraham and Mr. Parker, ATSDR, EPA Region VII). The soil samples from the 18 designated training areas were analyzed for 6 explosives (TNT, dinitrotoluene, nitrotoluene, trinitrobenzene, dinitrobenzene, andnitrobenzene).

Analytical results demonstrated TNT levels of less than 10 ppm in over 90 percent of 1,070samples; however, 13 samples demonstrated TNT levels between 20 to 55 ppm. One soil samplerevealed 1,000 ppm of lead; however, the area where sampling occurred is overgrown withvegetation.

The ATSDR is concerned over the possibility of radioactive contamination existing at this site.Weldon Spring Quarry, a different Operable Unit on-site, received radioactive wastes from theSt. Louis Airport Storage Site, the Hazelwood Interim Storage Site, and the Futura Coatings Site.These wastes consisted of thorium and radium wastes from uranium processing in the 1940's and1950's. The U.S. Department of Energy (DOE) only characterized areas where there wasreasonable expectations of radioactive contamination. Radioactive contamination is not expectedto be present in the areas designated for training according to DOE and EPA (personnelcorrespondence between Dr. Abraham, ATSDR and Mr. Greg McCabe, RPM, EPA Region VII, March 12, 1990). However, a radiological survey iswarranted to rule out an unexpected exposure to possible radioactive contaminants that may existat the designated training areas. We have discussed our concerns with Dr. Paul Charp, HealthPhysicist, ATSDR who agrees that a walkover survey is necessary, before troops are allowedaccess to the site.

The draft Remedial Investigation (ref. 3) mentioned that Building G-24 may contain asbestos. This building is located within the designated training areaand currently is not occupied. This building is restricted until sampling reveals the absence ofasbestos.

Troops training on-site may be exposed through direct contact, ingestion, and inhalation ofcontaminants. However, it does not seem likely that such exposure would be significant towarrant concern. The scenarios described (ref. 3) overestimate the opportunity for contact with,inhalation of, and ingestion of contaminated soil from the site; The general population will nothave access to the site.

CONCLUSION

Based on the information reviewed, lead and TNT and related compounds from the designatedtraining areas on-site pose minimal health risks to U.S. Army Reservists. Exposure tocontaminated soils through direct contact, inhalation, and ingestion is possible but not probableunder conditions described.

There is a possibility of radioactive contaminants existing on the designated training areasbecause of past disposal activities within the nearby vicinity. Moreover, the possible presence ofasbestos in Building G-24 may pose a health risk to soldiers or other on-site personnel. Exposureto contaminated soils through direct contact, inhalation, and ingestion is possible but notprobable under the conditions described.

The conclusion reached for the exposure scenarios evaluated in the Addendum are reasonablerisk estimates. However, the assumptions used probably do not represent actual conditions of riskand may or may not overestimate the risk of chronic exposure to the troops training on-site.

RECOMMENDATIONS

  1. Perform a radiological survey of the designated areas to rule out the possibility of exposure to radioactive contaminants to soldiers.
  2. Confine activities to only those designated training areas described in the Draft Remedial Investigation.
  3. Periodic monitoring of the training area should be implemented if disruption of the present environmental conditions occurs (e.g., digging trenches, etc.).
  4. Continue to restrict Building G-24 until inspection reveals the absence of asbestos.

PREPARER OF REPORT

Environmental and Health Effects Assessor: John E. Abraham,
Ph.D, M.P.H.
Environmental Health Scientist
Emergency Response and Consultation Branch
Regional Representative: David A. Parker
Public Health Advisor
Regional Services
Region VII



DEPARTMENT OF HEALTH AND HUMAN SERVICES

Toxicologist Emergency Response Branch, Office of Health Assessment, ATSDR

April 24, 1989, Health Consultation: Fish Data, Chemical Plant Site St. Charles County,Missouri.

Mr. David Parker
Public Health Advisor
EPA Region VII Kansas City, Missouri
Through: Chief, Emergency Response Branch, OHA, ATSDR

BACROUND

The United States Department of Energy (DOE) has completed a fish survey of lakes and pondsat the Weldon Spring Site (WSS) in St. Charles County, Missouri. The WSS is a DOE surplusfacility which was previously operated as an ordnance facility by the Department of the Armyand as a uranium processing facility by the Atomic Energy Commission. Several ponds aresuspected of having elevated heavy metal contamination resulting from surface water run-offfrom previous site activity. The Environmental Protection Agency (EPA) has requested theAgency for Toxic Substances and Disease Registry (ATSDR) to evaluate the fish data for humanhealth concerns.

DOCUMENTS REVIEWED

Radiological and Chemical Uptake by Selected Biota at the Weldon Spring Site, Draft,November 1988, Department of Energy, DOE/OR/21548-044,

DISCUSSION

The Food and Drug Administration has estimated the average consumption rate of commercialfish for the typical American is around 19 grams per day. The consumption rate for the upper95th percentile is estimated to be 27 grams of fish per day. While the typical American willconsume commercial fish from a variety of sources, sports fishermen and subsistence fishermenare more likely to consume greater quantities of fish than the average American and to consumefish from a restricted geographic area. Therefore, these two subpopulations may be at increasedrisk when consuming contaminated fish from a particular area. Studies on sports fishermen in theGreat Lakes area have shown that, on average, 32 pounds. of sport caught fish are consumed eachyear with certain individuals consuming as much as 3 to 5 times this average amount. Thisaverage fish consumption rate is equivalent to 1 fish meal per week which approximates 280grams of fish per week or 39.8 grams per day.

Proportionate, composite, fillet samples of sunfish, bass, and crappie were collected from WSSlakes. Catfish were not included in composite samples. Using 39.8 grams fish per day toapproximate the fish intake for sport fishermen, one can calculate daily and weekly intake formercury (Table 1), lead (Table 2) and arsenic (Table 3).

Sport and subsistence fishermen may have a favorite lake or fishing spot from which they obtainthe majority of their fish; therefore, the most conservative approach in this case is to assume thatthe fish consumed are from the lakes with detectable levels of the metal of concern. A great dealof variation can exist in calculated intakes levels. Because these are average values fromcomposite samples, levels are higher in half the fish sampled. Also, variation in heavy metalcontent in fish fillets certainly exists both within species (depending upon age) and betweenspecies (depending upon feeding habits and pharmacokinetics). The manner in which the fillet isprepared for analysis also affects the quantitative results. Therefore, it would be prudent not torely strictly upon the quantitative results.

The FDA has calculated the dietary intake of mercury in the typical American diet to be 3.2ug/day. For the adult who consumes one contaminated fish meal per week, the weekly intake formercury from lakes 34, 35, 36, and 37 would range from 44 - 75 ug/week or 6 - 11 ug/day (seeTable 1). This intake is greater than the acceptable intake from water based upon EPA'sMaximum Contaminant Level (MCL) of 2 ug/l and is similar to EPA's Rfd for mercury of 0.158ug/kg/day which is equivalent to an intake of 11 ug/day for a 70 kg adult male. The World HealthOrganization has established a maximum tolerable intake of 0.3 ug organic mercury/kg/day foradults. This corresponds to 15 to 21 ug of organic mercury per day for adult females and males.The WHO maximum tolerable level was based upon the observation that the long-term dailyingestion of approximately 250 ug per day of mercury as methyl mercury has been observed tocause the onset of neurological impairment. For individuals consuming 1 fish meal per weekfrom fish caught at the WSS, intake levels appear to be below levels that may cause adversehealth effects. This conclusion may not be valid for individuals who are consuming fish fromWSS on a more frequent basis.



Table 1.

Daily and weekly intake values for mercury are depicted for fish consumption where 39.8 g/day of contaminated fish are consumed. This intake level approximates 1 fish meal per week for sport and subsistence fishermen.
lake composite concentration
(ug/g)
daily intake
(ug/day)
weekly intake
(ug/week)
34 0.27 10.7 75.2
35 0.24 9.5 66.9
36 0.16 6.4 44.6
37 0.23 9.2 64.1

The FDA has estimated an intake of 57 ug/day of lead for the typical American diet. From lead infish from lakes 34 and 36, the estimated intake from 1 contaminated fish meal per week isapproximately 1100 ug/week or 160 ug/day. This intake exceeds the intake of 100 ug/day usingEPA's MCL for lead of 50 ug/l and assuming a 2 l/day water consumption rate for the averageadult. Populations at increased risk to lead exposure include children and pregnant women, sincelead is capable of crossing the placental barrier. For each 100 ug per liter of oral lead intake, anincrease of 4-5 ug of lead per 100 ml of blood is expected. WHO has estimated that this intakelevel may cause a significant number of children to exceed the recommended blood lead level of25 ug per 100 ml blood. Lead from fish taken from lakes 34 and 36 has the potential forincreasing lead exposure to children and pregnant women who consume the contaminated fish.

Table 2.

Daily and weekly intake values for lead are depicted for fish consumption where 39.8g/day of contaminated fish are consumed. This intake level approximates 1 fish meal per week for sport and subsistence fishermen.
lake composite concentration
(ug/g)
daily intake
(ug/day)
weekly intake
(ug/week)
34 4.0 159 1,114
36 4.2 167 1,170

The FDA has calculated that the average American dietary intake for arsenic (As) is 46 ug/day.The predominant food source is seafood which ranges from 2 to 10 ug As/g. It is very unusual forfreshwater fish to have higher levels than those found in seafood.

For the adult who consumes 1 contaminated fish meal per week from fish taken from lakes 35and 37, the weekly intake of arsenic is about 3,800 ug/week or 550 ug/day. This intake is muchgreater than the intake established by EPA's drinking water MCL of 50 ug/l, which is equivalentto 100 ug/day based upon a 2 l/day water consumption rate. An intake of 550 ug/day would bequite unacceptable were the exposure occurring through drinking water. For subsistencefishermen and sport fishermen who have more than 1 fish meal per week from fish taken fromlakes 35 and 37, the intake of arsenic obviously would be greater.



Table 3.

Daily and weekly intake values for arsenic are depicted for fish consumption where 39.8g/day of contaminated fish are consumed. This intake level approximates 1 fish meal per week for sport and subsistence fishermen.
lake composite concentration
(ug/g)
daily intake
(ug/day)
weekly intake
(ug/week)
35 13.9 553 3,872
37 13.6 541 3,788

Daily intake from contaminated fish at the WSS site has been calculated from the mean fishconsumption rate for sport fishermen. Some sport fishermen will have higher intake than thoseused in these calculations. Also, it is very likely that subsistence fishermen in the area willconsume more locally caught fish when compared to sport fishermen. Therefore, their intake ofthese metals will be increased thus increasing their risk to adverse health outcome.

A problem does exist in the manner in which the fish were collected. The logic was used that fishare eaten according their proportional population within each lake. This logic does not seemreasonable to me for estimating fish consumption patterns since some residents may have apreference for certain species in their diet. In addition, catfish were not sampled in the survey forheavy metal content. It is very likely that catfish comprise a major portion of fish in the diet ofsubsistence fishermen. Catfish are also likely to have increased levels of heavy metal because oftheir close association with sediment feeding, which is the sink for heavy metals in ponds andlakes.

CONCLUSION

All individuals receive some quantity of mercury, arsenic, and lead from both dietary andenvironmental exposure routes. Quantitation of the environmental exposure route (i.e., air andsoil ingestion) is not precise and depends largely upon local conditions.

Quantitation of dietary intake has been made by FDA from food baskets surveys. The intake ofheavy metals found in fish at the WSS is in addition to this background exposure.

The occurrence of heavy metals in composite fish samples from the WSS does not present apublic health threat to area residents who have occasional fish meals from locally caught fish.However, sport fishermen and subsistence fishermen may be at increased risk to adverse healtheffects if a major portion of the fish in their diet comes from the lakes with heavy metalcontaminated fish. A great deal of variation exists in the fishing and eating habits of these twopopulations; therefore, it is difficult to quantitate their metal intake with certainty. By using theaverage consumption rate for sport fishermen from the Great Lakes area, one can obtain somequantitative idea of the potential intake levels. However, because of uncertainty in estimatingdietary fish intake, one should not rely strictly upon the quantitative results which tends toindicate a potential problem. The major concern involves those individuals and their familieswho rely heavily on fish from the WSS. This population has the potential for exceeding thesafety factor used in establishing acceptable heavy metal intakes.

RECOMMENDATIONS

1. Collect composite samples of species specific fish from lakes in the WSS. Include catfish as aseparate species to be evaluated.

2. Identify subpopulations, like sport fishermen and subsistence fishermen who might use thelakes at the WSS and educate them to the potential hazard.

3. Fish from the WSS should not be consumed more than once per month.

David N. Mellard, Ph.D.



ATSDR Record of Activity

February 10, 1993, Health Consultation

UID #:s j h 0 Date:02/10/93 Time:10:00 am X pm

Site Name: Weldon Spring City:Weldn Sprng Cnty:St Charles State:MO CERCLIS #: Cost Recovery #: 703S Region:07

Site Status (1) X NPL Non-NPL RCRA Non-Site specific Federal

(2) Emergency Response Remedial X Other

Activities

Incoming Call Public Meeting X Health Consult Site Visit

X Outgoing Call Other Meeting Health Referral Info Provided

Conference Call Data Review Written Response Training

X Incoming Mail Other

Requestor and Affiliation:(1 ) Cecilia Tapia EPA Region VII

Phone: (913) 551-7733 Address:

City: Kansas City State: KA Zip Code: 66101

Contacts and Affiliation

(31) Dave Parker ( )( ) ( )
1-EPA2-USCG3-OTHER FED4-STATE ENV5-STATE HLT
6-COUNTY HLTH7-CITY HLTH8-HOSPITAL9-LAW ENFORCE10-FIRE DEPT
11-POISON CTR12-PRIV CITZ13-OTHER14-UNKNOWN15-DOD
16-DOE17-NOAA18-OTHR STATE19-OTHRCOUNTY20-OTHR CITY
21-INTL22-CITZ GROUP23-ELECT. OFF24-PRIV. CO25-NEWSMEDIA
26-ARMY27-NAVY28-AIR FORCE29-DEF LOGAGCY30-NRC
31-ATSDR



Program Areas

Health Assessment Health Studies Tox Info-profile Worker Hlth

Petition Assessment Health Survellnc Tox Info-Nonprofil Admin

Emergency Response Disease Regstry Subst-Spec Resch Other

X Health Consultation Exposr Regstry Health Education

Narrative Summary: EPA requested that ATSDR comment on the health implications of lead,arsenic, and mercury in fish caught at the Weldon Spring site. Whole fish and fish fillets (edibleportion) were analyzed for the three metals using a detection limit of 0.10 mg/kg.

Lead was found in two whole fish samples above the detection limit at a maximum concentrationof 0.176 mg/kg. Mercury was found in a fish fillet at a maximum concentration of 0.212 mg/kg.Arsenic was not found in any whole fish or fish fillet samples above the detection limit.

Action Required/Recommendations/Info Provided: I advised EPA that the lead, arsenic, andmercury did not represent a health threat to persons eating the fish. I also advised EPA that, at thereported concentrations, harmful effects from subsistence consumption of fish would not beexpected.

cc: Ed Skowronski
RIMB
Dave Parker


1993 Letter on Proposed Cleanup Levels

Mr. Stephen H. McCracken
U.S. Department of Energy
Weldon Spring Site
Remedial Action Project Office
7295 Highway 94 South
St. Charles, Missouri 63304

Dear Mr. McCracken:

The Agency for Toxic Substances and Disease Registry has been asked to provide writtencomments to you concerning the public health aspects of the "Proposed Plan for Remedial Actionat the Chemical Plant Area of the Weldon Spring Site". This document proposes remedial actionsfor contaminated materials, soil cleanup standards, and identifies a disposal decision for wastesgenerated during remediation. This letter will address the adequacy of the proposed soil cleanupstandards and the potential for human exposures to those waste materials.

The public health concerns of the proposed remedial actions are specifically addressed in anATSDR Health Consultation, which is currently in internal review. This letter is to insure thatATSDR comments are received during the public comment period for the proposed plan. TheHealth Consultation will also be forwarded to you as soon as possible.

ATSDR has two primary concerns with the proposed plan. First, the off-site (or vicinity)properties which have been determined to have radiological contamination have not beenevaluated for non-radiological contaminants. Although cleanup of radiological contaminants atthese sites may remove/remediate non-radiological contamination, these are the sites for whichthere is current exposure potential and DOE will not retain access restrictions. Additionally,several of the off-site areas may have been subject to prior contamination by Ordnance Worksoperations, which presents the potential for significant remedial worker exposure and safetyhazards. ATSDR recommends, that in the off-site areas, non-radiologic soil contaminantscreening be conducted and that site remediation be coordinated with ongoing Ordnance Workssite characterization.

The second concern is the proposed cleanup standards (ALARA Goals). The ALARA Goals forarsenic, chromium VI, dinitrobenzene, nitrobenzene, trinitrobenzene, and trinitrotoluene exceedhealth-based comparison values for ingestion exposures for pica children (assumed soil ingestionrate of 5,000 mg/day). The ALARA Goals for dinitrobenzene, nitrobenzene, and trinitrobenzeneare also greater than comparison values for non-pica children (assumed soil ingestion of 200mg/day). Arsenic, PAHs [benzol(a)pyrene], and PCBs (Aroclor 1248, 1254, and 1260) areknown or suspected carcinogens and the proposed ALARA Goals are greater than appropriatecomparison values.

Calculation of the comparison values assumes chronic exposure to the contaminated soil.Currently, there are no chronic exposures to Chemical Plant Site soils for the public because siteaccess is restricted. However, the cleanup goals were derived assuming unlimited public access.Under the scenario of residential occupation of the contaminated area, the proposed cleanupgoals would not be protective of human health. Thirdly, the proposed plan has not demonstrated that future potential doses due to radioactivematerials at the site will be within the recommendations of the International Commission onRadiation Protection (ICRP Publication 60). Calculation of radiation dose includes theaccumulation of radioactive materials within the body throughout one's expected life (i.e. 70years). The proposed plan does not detail how or if that was completed.

Using the Baseline Assessment for the Chemical Plant Area of the Weldon Spring Site (BHA) asan indicator, the BHA included calculations for doses over an individuals working-life-span of50 years for either 10 year or 30 year exposure scenarios. Those scenarios do not include doseestimates for the pca-child nor are they representative of the public's expected life-span. Todetermine whether the ALARA Goals for the radioactive soil are protective of public health,exposure scenarios should account for pica-child, child, and adult activities. The doses fromthose scenarios should be evaluated for the expected life-span of an individual, 70 years, asspecified by the ICRP.

Accidental or intermittent exposure to soils remediated to ALARA Goals should not be of publichealth concern if safety procedures and site access restrictions, as outlined in the "FeasibilityStudy for Remedial Action at the Chemical Plant Area of the Weldon Spring Site", aremaintained.

Respectfully yours,

Sally L. Shaver
Chief
Federal Programs Branch
Division of Health Assessment
and Consultation


January 20, 1994, Health Consultation

Record of Decision for Quarry Bulk Wastes, Weldon Spring Remedial Action Project,(703S)

Federal Programs Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry

January 20, 1994

BACKGROUND AND STATEMENT OF ISSUES

The Agency for Toxic Substances and Disease Registry (ATSDR) was requested by the UnitedStates Department of Energy (DOE) to evaluate the human health hazards posed by its InterimRemedial Action Plan for removing bulk wastes from the Weldon Spring quarry. As described inthe Record of Decision [ROD; 1], the plan calls for bulk wastes to be removed from the quarry,using standard equipment and procedures, and transported to a temporary storage area at theChemical Plant site using a private road. This ROD does not include information or remedialalternatives for the following: 1) permanent disposal of the bulk wastes, 2) the quarry proper, 3)surface water, or 4) groundwater.

A. Background

The Weldon Spring quarry is a 15-acre area of the Weldon Spring Quarry/Plant/Pits site (220total acres) that was listed on the EPA National Priorities List (NPL) in July 1987. In March1989, this listing was expanded to include the chemical plant and raffinate pits. The quarry isabout 4 miles south-southwest of the chemical plant area, 5 miles southwest of the city ofWeldon Spring, 1 mile west of the Missouri River, and about ½ mile northwest of the St. CharlesCounty wellfield. The quarry is on Missouri Route 94, but public access is restricted by a fenceand 24-hour security guard. The quarry is about 1,000 ft. long, 450 ft. wide, covers an area of twoacres, and the depth varies from about 30 to more than 100 ft. [2].

Before 1942, the quarry was used as a source of construction limestone. From 1942 to 1957, theArmy (or its contractors) used the quarry to dispose of off-specification explosives andexplosive-contaminated materials. From 1957 to 1969, the quarry was used to dispose ofbuilding rubble, soil, and sludges contaminated with radioactive materials. The RemedialInvestigation for Quarry Bulk Wastes [3] summarizes contaminant concentrations anddistributions and estimates the total volume of waste within the quarry is 95,000 cubic yards. TheBaseline Risk Evaluation [2] identifies specific contaminants of concern, average concentrations,ranges, and estimated waste volumes.

B. Statement of Issues

Several studies, as summarized in the Remedial Investigation [3] and the Baseline RiskAssessment [2], have identified the bulk wastes in the Weldon Spring quarry as hazardousbecause of radiological and chemical contamination. ATSDR previously identified the quarry asa public health concern because of the potential for on-site radiation exposure, bioaccumulationof contaminants in food chain, and migration of contaminants to the St. Charles County wellfield[4]. Excavating the waste material and transporting it to temporary storage at the chemical plantsite is the alternative specified in the ROD [1]. The basic issue addressed in this consultation iswhether the proposed activity is protective of public health.

DISCUSSION

Remedial workers may be exposed to quarry bulk wastes during the excavation, transport, andstorage processes. The use of dust suppression techniques, site and waste monitoring, workertraining, and other standard procedures for minimizing worker exposures as indicated in theFeasibility Study [5] should eliminate the potential for adverse health effects. Mitigativemeasures to be used for worker protection include: 1) developing an activity-specificenvironmental, safety, and health plan; 2) monitoring worker health/exposure; 3) monitoring theworkplace environment; and 4) making available and using protective equipment, such asrespirators, protective clothing, and showers (if necessary). Public and worker exposures duringquarry excavation will be mitigated by keeping inactive excavation areas covered, wetting theactive excavation area and materials, and covering surfaces and materials.

The waste materials will be transported in closed containers on a private haul road so that publicexposures do not occur during transport. Public exposure during excavation is unlikely becausethere are no residents or businesses adjacent to the quarry. Worker exposure is possible as aresult of radon inhalation and transportation accidents; however, mitigative measures to preventsuch accidents will include: 1) transport in closed, leakproof trucks (DOT approved for transportof low-specific activity materials), 2) vehicle decontamination before quarry departure, 3) a 20mph speed limit, 4) personal protective equipment, and 5) pressurized truck cabs.

Public exposure to bulk wastes during temporary storage at the chemical plant is not likelybecause of access restrictions, site monitoring, and the design characteristics of the storage area[5]. The temporary storage area (TSA) at the chemical plant site is within a patrolled, chain-link/barbed wire fence enclosure. Sludge retention areas within the TSA will be double-linedwith stormwater runoff and leachate diverted to lined collection ponds and the water-treatmentplant. Areas of the TSA susceptible to wind-erosion will be covered and dust-suppressiontechniques will be used for the entire area [5]. The TSA contains site monitors for airparticulates, radon, and radon-decay products, and groundwater monitoring of chemical andradioactive contaminants.

CONCLUSIONS

The quarry is a public health concern and overall remediation of the site requires excavating andremoving bulk wastes. Based on available data, the excavation, transport, and temporary storageof the quarry bulk wastes will not present a potential for public exposures to hazardous wastes.There is a potential, however, for worker exposure, but that can be minimized if existing standardprocedures for dust suppression, site monitoring, worker training, and safety procedures arefollowed. These conclusions are specific to the quarry bulk wastes and should not be consideredapplicable to quarry surface water, groundwater, or residual contamination after removal of bulkwastes.

RECOMMENDATIONS

ATSDR recommends that the following steps be taken to protect public health:

  • excavation, transport, and temporary storage of quarry bulk wastes should be considered the first step in remediating the quarry;
  • standard dust suppression techniques and other procedures proposed for minimizing workerexposures should be used during all phases of the remediation activity. Also, because of thepotential for worker exposures to hazardous materials, the existing activity-specific safety planshould be followed during the remedial action.

PREPARER OF REPORT:

    Mark W. Evans, Ph.D
    Environmental Geologist
    Energy Facilities Assessment Section
    Federal Programs Branch
    Division of Health Assessment and Consultation

REFERENCES
  1. Environmental Assessment and Information Sciences Division, Argonne National Laboratory. Record of Decision for the Management of Bulk Wastes at the Weldon Spring Quarry, Weldon Spring, Missouri. June 1990.
  2. Environmental Assessment and Information Sciences Division, Argonne National Laboratory. Baseline Risk Evaluation for Exposure to Bulk Wastes at the Weldon Spring Quarry, Weldon Spring, Missouri. January 1990.
  3. MK- Ferguson Company and Jacob Engineering Group. Remedial Investigations for Quarry Bulk Wastes (Revision 1). December 1989.
  4. Agency for Toxic Substances and Disease Registry. Preliminary Health Assessment for Weldon Springs Site. St. Charles County, Weldon Spring, Missouri. Atlanta: ATSDR, December 1988 (amended March 1990).
  5. U.S. Department of Energy, Oak Ridge Operations Office. Feasibility Study for Managementof the Bulk Wastes at the Weldon Spring Quarry, Weldon Spring, Missouri. February 1990.


August 30, 1994, Health Consultation

Evaluation of Potential Radiation Exposures at the Francis Howell High School from theWeldon Spring Site,
Weldon Spring Remedial Action Project, (703S)

Federal Facilities Assessment Branch
Division of Health Assessment and Consultation

August 30, 1994

BACKGROUND AND STATEMENT OF ISSUES

The St. Charles Countians Against Hazardous Waste have requested the Agency for ToxicSubstances and Disease Registry (ATSDR) to evaluate potential exposure of the Francis HowellHigh School students and staff to radioactive materials from the Weldon Spring Site (WSS). Thehigh school has approximately 2,300 students and staff members and is located approximatelyone-half mile east of the WSS [1]. Demolition of buildings contaminated with uranium (U),thorium (Th), or radium (Ra) is underway and may be a source of airborne particulates.

The WSS is an inactive uranium processing facility that is currently managed by the Departmentof Energy (DOE) as a U.S. Environmental Protection Agency (EPA) Superfund site. The siteincludes four processing waste lagoons (raffinate pits), the Chemical Plant buildings andgrounds, a nearby quarry used for mixed waste disposal, and other off-site areas containingradioactively contaminated soils [1]. The WSS was built on part of a 17,000 acre WWII eraordnance plant (Weldon Spring Former Ordnance Works; WSFOW) that manufactured TNT andDNT munitions and resulted in widespread chemical contamination [2]. The former ordnanceworks is also an EPA Superfund site that is being cleaned up by the U.S. Army.

The WSS is in St. Charles County, Missouri, 30 miles west of St. Louis and about 2 miles westof the Weldon Spring and Weldon Spring Heights communities [1]. The WSS is bordered bystate-owned wildlife management areas to the north, south and east, and by the Weldon SpringTraining Area (WSTA) to the west. The former ordnance works included all of the wildlifemanagement areas, the WSS and the WSTA. The WSTA is controlled by the Army and used fortroop training activities. People hunt, fish, and hike in the wildlife management areas, whichinclude some areas of radioactive and chemical contamination [3]. A state-owned highwaymaintenance facility is adjacent to the WSS along the east boundary.

Radioactive and chemical contamination of both on- and off-site soil, sediment, surface water,and groundwater at the WSS have resulted from past operations of the uranium refining facilityand the ordinance manufacturing facility [2]. However, both surface waters and groundwaterfrom the site flow north or south and away from the high school, and the resulting contaminatedlake and stream sediments follow the same drainage pattern to the north and south [1].

ATSDR reviewed a 1986 survey of radioactive contamination which indicated that the onlysignificant sources for airborne releases at WSS and nearby areas lie within the boundaries of theWSS [4]. The study did not report any data for the high school property; however, Highway 94,which leads to the high school, was monitored and no elevated gamma readings were found onHighway 94 near the high school.

DOE has collected the following environmental data which ATSDR reviewed for thisconsultation. ATSDR reviewed the annual alpha air monitoring data which are used to monitormigration of radionuclides which decay through alpha emission (i.e., uranium, thorium, and theirdecay products). In 1989 and 1990, WSS reported gross airborne alpha concentrations in amanner consistent with DOE guidelines at the time: if the measured alpha radioactivity wasbelow the "lower level of detection" (LLD) of the analyzing instrument, the LLD was reportedinstead of the measured activity. These data are preceded by the less than symbol (<) [5,6]. In1991, WSS, consistent with changing DOE guidelines, stopped the use of LLD values whenreporting gross alpha concentrations [7]. ATSDR reviewed ambient radon concentrations nearthe Francis Howell High School and background locations reported by WSS for the years 1989 -1991. ATSDR also reviewed particulate radionuclide concentrations in air [4]. Isotopic analysisof air samples collected from the Francis Howell High School and background locations wereperformed by WSS from 1990 to 1993. The radionuclides measured by WSS include U-238, U-235, U-234, Th-230, Ra-226, Th-232, Ra-228, and Th-228.

DISCUSSION

ATSDR compared gross3 alpha air concentrations at different locations to determine if alpha-emitting radionuclides are migrating from their source locations. If the measured gross alpha airconcentrations are greater than that of background, then migration of alpha emittingradionuclides may be occurring from source areas. (Gross alpha data alone are not sufficient forcalculating radionuclide concentrations in air.)

Because WSS reported the gross alpha concentrations with LLDs ("<") prior to 1991, datareported prior to 1991 can not be compared to data collected subsequently. Therefore, ATSDRhas used 1991, 1992, and 1993 gross alpha data; and their averages are tabulated below in Table1.

Table 1.

HAVERAGE ANNUAL GROSS CONCENTRATIONS IN AIR (10-15Ci/ml).
Monitoring Location199119921993
Chemical Plant & RaffinatePits1.401.181.14
Quarry1.521.101.11
High School1.361.061.04
Background1.371.231.02

µCi/ml - microcurie per milliliter

The 1991, 1992, and 1993 average gross alpha concentrations at the perimeter of contaminatedareas are essentially the same as levels at the high school and background locations. Thisindicates that no migration above background of alpha-emitting radionuclides in air occurredfrom the chemical plant, the raffinate pits, or the quarry towards the high school between 1991and 1993 [this includes the recent period of building demolition at the site].

ATSDR also compared the range of radon concentrations (alpha track results reported 1989 -1991) in background areas to the range at the high school. The range of radon concentrations inbackground areas is 0.04 - 1.3 picocurie per liter (pCi/L) of air, and the range at the high schoolis 0.1 - 0.8 pCi/L. The range of radon concentrations at the high school is within that ofbackground areas; therefore, radon emissions from the WSS do not appear to impact persons atthe high school. Furthermore, radon levels at both the high school and WSS do not represent apublic health concern.

In 1990, WSS began performing isotopic analyses of particulate air samples [6]. The results ofisotopic analyses are at or near the analytical detection limits, and the uncertainty associated withthe results are large [10]. Therefore, ATSDR did not use these data.

CONCLUSIONS

1) ATSDR concludes that contamination from WSS and building demolition does not pose apublic health concern for persons at the Francis Howell High School. This conclusion is basedon the following information: the characterization study, which indicates that property at the highschool is not contaminated; gross alpha measurements, which show that no airborne migration ofalpha-emitting radionuclides is occurring from the site to the high school; and radon data, whichindicate that radon emissions from WSS do not contribute to radon exposures at the high school.

RECOMMENDATIONS

1) Continue monitoring airborne radionuclides at appropriate locations in order to ensure publicconfidence in the waste management processes at the WSS.

Consultation Prepared By:

    Michael Grayson

    Mark W. Evans, Ph.D.

    William Taylor, Ph.D.

    Jack Hanley

REFERENCES

  1. Environmental Assessment and Information Sciences Division, Argonne National Laboratory. Proposed Plan for Remedial Action at the Chemical Plant Area of the Weldon Spring Site. November 1992.
  2. MK-Ferguson Company and Jacob Engineering Group. Remedial Investigation for the Chemical Plant Area of the Weldon Spring Site (DOE/OR21548-074). November 1992.
  3. U.S. Department of Energy, Oak Ridge Field Office WSSRAP. Baseline Assessment for the Chemical Plant Area of the Weldon Spring Site (DOE/OR21548-091). November 1992.
  4. U.S. Department of Energy, Division of Remedial Action Projects. Radiological Survey of the August A. Busch and Weldon Spring Wildlife Areas. April 1986.
  5. U.S. Department of Energy. Annual Site Environmental Report for Calendar Year 1989 for the Weldon Spring Site Remedial Action Project (DOE/OR/21548-129). Oak Ridge: U.S. Department of Energy. November 1990.
  6. U.S. Department of Energy. Annual Site Environmental Report for Calendar Year 1990 (DOE/OR/21548-193). Oak Ridge: U.S. Department of Energy. September 1991.
  7. U.S. Department of Energy. Weldon Spring Site Environmental Report for Calendar Year 1991 (DOE/OR/21548-283). Oak Ridge: U.S. Department of Energy. May 1992.
  8. U.S. Department of Energy. Weldon Spring Site Environmental Report for Calendar Year 1992 (DOE/OR/21548-372). Oak Ridge: U.S. Department of Energy. June 1993.
  9. U.S. Department of Energy. Weldon Spring Site Environmental Report for Calendar Year 1993 (DOE/OR/21548-436). Oak Ridge: U.S. Department of Energy. March 1994.
  10. Letter from Stephen H. McCracken, DOE, St. Charles Missouri, to Dr. Mark Evans, ATSDR,Atlanta Georgia. April 15, 1994.

APPENDIX F: RESPONSE TO PUBLIC COMMENT

ATSDR released the Public Comment draft of the Public Health Assessment of the WeldonSpring Quarry/Plant/Pits (USDOE) on September 30, 1996. The comment period endedNovember 29, 1996. During that period, we received one comment from the public. A summaryof that comment and our response is provided below.

Comment:
"...There is one area which I believe has been omitted in trying to identify a reasonfor the excessive leukemia rate in St. Charles County. As shown in some of the County's wells,radioactive contamination is a factor due to underlying bedrock in St. Charles County. Apparently there lies a bed of radioactive rock some 300 feet below the surface, which hascontaminated some wells in the county. Could someone look into the possibility of radon arisingfrom this deeply buried layer of radioactive materials? At this point, some further studies couldbe done by placing radon monitors in many basements and homes in the County where actualcases of leukemia have occurred. If this proves to identify no radon, then one more cause can beruled out...."
Response: Generally, an excessive leukemia rate would not be attributed to radon emanatingfrom a bedrock 300 feet below the surface for two reasons, (1) radon sources located more than afew meters (6.5 - 10 feet) below ground are unlikely to increase radon concentrations at thesurface1, and (2) although leukemia has been linked to radiation exposure, specifically elevatedgamma and x-ray exposure, it has not been causally linked to radon exposure.


1. From the National Council on Radiation Protection and Measurements, Report No. 103, p. 5.



FOOTNOTES

1. The annual limit on intake (ALI) of the public is used as the annual amount of a radionuclide a member of the public can inhale or ingest which delivers the annual public dose limit of 100 mrem per year.

2. ATSDR uses the most current ALIs listed in ICRP 61.

3. Gross alpha concentrations = net concentrations due to source + concentrations due to background


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