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Abbreviations and Acronyms

AEC - Atomic Energy Commission

ATSDR - Agency for Toxic Substances and Disease Registry

CERCLA - Comprehensive Environmental Response Compensation and Liability Act, or Superfund

CLHA - Child Longer-Term Health Advisory

COE - (U.S. Army Corps of Engineers

CREG - Cancer Risk Evaluation Guides

CSF - Cancer Slope Factors

CV - (ATSDR) Comparison Value

DOE - U. S. Department of Energy

EFAS - (ATSDR Division of Health Assessment and Consultation)
Energy Facilities Assessment Section

EMEG - Environmental Media Evaluation Guides

EPA - U.S. Environmental Protection Agency

ft. - feet/foot

IQ - Intelligence Quotient

kg - kilogram

L - liter

LOAEL - Lowest Observable Effects Level

LTHA - Lifetime Health Advisory

MDOC - Missouri Department of Conservation

mg - milligram

MGD - Million Gallons per Day

mg/kg - milligram per kilogram

mg/L - milligrams per liter

MRL - Minimal Risk Level

NPL - National Priorities List

NOAEL - No Observable Adverse Effect Level

OSHA - Occupational Safety and Health Administration

PAHs - Polycyclic Aromatic Hydrocarbons

PCBs - Polychlorinated Biphenyls

PHAP - Public Health Action Plan

ppb - part per billion

ppm - part per million

RI - Remedial Investigation

RI/FS - Remedial Investigation/Feasibility Study

RMEG - Reference Media Evaluation Guide

SVOC - semivolatile organics

TCLP - Toxicity Characteristic Leaching Procedures

WSCP - Weldon Spring Chemical Plant

WSOW - Weldon Spring Ordnance Works

WSSRAP - Weldon Spring Remedial Action Project

WSTA - Weldon Spring Training Area

WW I - World War I

WW II - World War II

1,3-DNB (DNB) - Dinitrobenzene

1,3,5-TNB (TNB) - Trinitrobenezene

2,4-DNT (DNT) - Dinitrotoluene

2,6-DNT (DNT) - Dinitrotoluene

2,4,6-TNT (TNT) - Trinitrotoluene


Description of ATSDR Comparison Values

The conclusion that a contaminant exceeds the CV does not mean that it will cause adverse healtheffects. CVs are contaminant concentrations in specific media that are used to selectcontaminants for further evaluation to determine the possibility of adverse public health effects.

Background concentrations

    Background concentrations for the state, region, or nation can be used for comparison, whenbackground samples for the medium of concern, such as soil, have not been collected and whenother comparison values do not exist. Background concentrations can be used provided themedium has the same basic characteristics as the medium of concern at the site.

Cancer Risk Evaluation Guides (CREGs)

    CREGs are estimated contaminant concentrations that would be expected to cause no more thanone excess cancer in a million (10E-6) persons exposed over a lifetime. CREGs are calculatedfrom EPA's cancer slope factors (CSFs).

Environmental Media Evaluation Guides (EMEGs)

    EMEGs are based on ATSDR minimal risk levels (MRLs) and factor in body weight and ingestionrates. An EMEG is an estimate of daily human exposure to a chemical (in mg/kg/day) that islikely to be without an noncarcinogenic effects over a specified duration of exposure to includeacute, intermediate, and chronic exposures.

Lifetime Health Advisory (LTHA)

    An LTHA represents contaminant concentrations that EPA considers protective ofnoncarcinogenic health effects during a lifetime (70 years) of exposure. Drinking waterconcentrations are developed to predict acceptable exposure levels for both adults and childrenwhen data on a NOAEL or LOAEL exist from animal or human studies. LTHAs are not legallyenforceable standards.

Reference Media Evaluation Guide (RMEG)

    RMEGs are derived by ATSDR from the EPA oral Reference Dose. It is the concentration inwater or soil at which daily human exposure is unlikely to result in adverse noncancerous effects.

Reference Dose (RfD)

    An RfD is EPA's estimate for the human population (including sensitive subpopulations) of thedaily exposure by the oral route likely to be without appreciable risk of deleteriousnoncarcinogenic effects during a lifetime (70 years) of exposure.

Child Longer-Term Health Advisory (CLHA)

    A CLHA is derived by EPA. It is a drinking water concentration at which adverse,noncarcinogenic health effects would not be expected to occur in children after exposure up to 7years in duration.


Polycyclic Aromatic Hydrocarbons in Surface Soils at WSTA

PAH Surface Soil Contaminants at WSTA
CompoundMaximum Concentration
Comparison Value
benz(a)anthracene3.1 EPA B2 no numeric value
benzo(a)pyrene2.20.1 CREG
benzo(k)fluoranthene7.4EPA B2 no numeric value
chrysene7.4EPA B2 no numeric value
ideno(123cd)pyrene1.1EPA B2 no numeric value

Appendix D
Evaluation of Incineration

The Proposed Plan for remediation for Operable Unit One at WSTA envisions incineration as analternative for treatment for much of the contamination at the site. Incineration is a remedialalternative which can be a concern to members of the public in terms of its safe use. ATSDR willreview the proposed plans for any of the remedial alternative chosen. However, due to thepotential high level of interest in incineration, a preliminary evaluation is provided here.

As proposed, incineration will be used to remediate the pipelines and contaminated soil. Groundwater and surface water contamination will be dealt with in the future proposed plans forOperable Unit Two. Remediation for these media will be determined as the effect of soilremediation is evaluated, with the expectation that soil remediation will remove the source ofgroundwater and surface water contamination (3).

Based on their evaluation of various alternatives, the Army and EPA support incineration of soilcontaminated with nitroaromatics, PAHs, and PCBs, and incineration of the waste waterpipelines.

The incinerator is a natural gas-fired rotary kiln which will heat the contaminated material toabout 1200 degrees Fahrenheit (oF), volatilizing the nitroaromatics. These nitroaromatics are thencarried into a secondary combustion chamber and destroyed at about 1700oF. Dust particles arethen separated and any remaining gases are treated in a wet scrubbing system, baghouse orelectrostatic precipitator (23). Currently, ATSDR does not have information on which of theseprocesses will be employed.

EPA will monitor the process to ensure that the incinerator destroys or removes 99.99% of thecontaminants (23). Due to the relatively high lead levels in the soil, air pollution controlequipment that is very efficient in removing lead and particulates,including asbestos, will be veryimportant for the safe and effective operation of this unit (24).

According to specifications written by EPA, monitoring will be continuous and instantaneous, sothat in the event that requirements are not met for any reason, the process can be immediatelyshut down. The effluents resulting from the process are to be a gas stream which meetsrequirements protective of human health, and incinerated soil, which may contain nitroaromatics,but at a level which will also not be a threat to human health (3).

Soil contaminated by nitroaromatics will be incinerated and will backfilled into the originalexcavations. Nitroaromatic- and lead-contaminated soil will be incinerated, stabilized andConstruction debris will be disposed in an onsite landfill. Lead-contaminated soil will becontained in an onsite landfill. The landfill intended for containment of lead-contaminated soil willbe double-lined on sides and bottom, with a leachate collection system and leak detection system(3). The WSOW FS states that each landfill would be required to meet RCRA requirements forsoil, geologic and hydrologic conditions, liners, monitoring systems, leachate collection,operation, maintenance and service facilities. These requirements are specified by RCRA SubtitleC hazardous waste regulations in 40 CFR 264 and by land disposal restrictions specified in 40CFR 268. Lead-contaminated soils would be required to pass Toxicity Characteristic LeachingProcedure (TCLP) testing. RCRA also requires that any nitroaromatic-contaminated soils betreated to reduce or eliminate reactivity (6).

The proposed plan (3) for remediation of on-site soils contains insufficient information on thedesign of the incinerator to estimate what the impacts may be on the local community. However,thermal destruction (incineration) is probably the most effective way to destroy the TNT andDNT present, and a properly designed and operated incinerator can be run in a manner to beprotective of public health. If appropriately stringent precautions are maintained, use of theincinerator described can be protective of public health (24). As previously stated, ATSDR willreview, for the effect on public health, all proposed work plans for remedial alternative(s) chosen.

Toxicological Evaluations


The following is a brief description of the health effects of exposure to nitroaromatics. Theunderstanding of the effects on humans are based on the evaluation of exposure by way ofinhalation of pure product during manufacturing activities. The concentrations in soil areobviously many orders of magnitude smaller that those which would have been encountered in theproduction facilities by workers. And, once again, the current exposures expected are short-termand infrequent.

It was during large-scale production of TNT during WW I that the toxic effects of TNT were firstwell documented. Many workers in munitions factories died of TNT intoxication. Withapplication of hygienic precautions (such as periodic hand-washing, routine changes of protectiveclothing, and respiratory protection) to prevent inhalation exposure, fatalities decreased. Liverdisease and aplastic anemia (an often fatal bone marrow disorder that causes anemia and otherchanges in the blood) were the primary causes of death. Absorption of TNT through the skin orlungs can produce cyanosis (lack of oxygen-carrying capacity of the blood), severe liver damage,anemia, cataract formation, CNS manifestations, and kidney damage.

Long-term, low-dose TNT-ingestion studies have been carried out in mice, rats, and dogs. Athigher doses in mice and rats over a 24 to 26-week period, hematological signs of anemia andliver damage were noted. When dogs were fed TNT over 26 weeks, liver damage was noted atall dosage levels. Increased incidence of urinary bladder papilloma (benign adn cancerous tumorsof the urinary baldder) and carcinoma was found in female rats. Using this study, EPA classifiedTNT as a Group C chemical (possible human carcinogen). It should be emphasized that theseeffects were the result of long-term exposure by ingestion, and not based on infrequent,incidental exposures such as would be expected to occur to site trespassers.(51)

No information is available on the health effects of TNB. Because of its structural similarity toDNB, assumptions are made that its health effects might be similar to those caused by DNB. Data about health effects after exposure to DNB are limited. Six workers exposed to an unknownconcentration of 1,3-DNB dust developed cyanosis that began within one day of exposure andlasted two weeks. Health effects also included anemia accompanied by palpitations, dizziness,and fatigue. Anemia persisted an average of three days. Follow-up examinations over a 10-yearperiod did not reveal any adverse health effects. Well-documented health effects in animalsinclude toxic effects resulting in death and pathological effects on the liver, spleen, and testes. These effects resulted in weight loss, anemia, and decreased reproductive capacity. Someevidence of increased toxicity in older (as compared to younger) animals was noted. A 16-weekstudy of ingestion by rats of 1,3-DNB in drinking water detected both splenic and testiculareffects. High uncertainty factors were included because of lack of long-term studies. DNB isconsidered a Class D chemical (not classified as to human carcinogenicity) because of lack ofinformation about its carcinogenicity. Because of the uncertainty of using DNB studies todevelop guidelines for TNB, additional safety assumptions were included in the calculations(51). Here again, as is the case with TNT, the effects noted are for long-term ingestion, not infrequent, incidental exposure as would occur with trespassers or with infrequent ingestion of surface water.


The effects of lead once it is in the body are the same, regardless of how it enters the body. Exposure to lead is especially dangerous to unborn children, infants and young children. Forinfants and young children, lead ingestion has been shown to decrease intelligence scores (IQ),slow growth and cause hearing impairment. Exposure to high lead levels can cause brain andkidney damage in both children and adults. The ability of lead to cause cancer in humans has notbeen shown. To date, workplace studies do not provide enough information to determine the riskto workers of cancer from lead exposure. However, some research with rats and mice haveshown tumors will develop in subjects fed large doses of lead.(52) The concentrations of lead insome soil samples at WSTA are elevated to the point where exposure may reasonably beconsidered a hazard.


EPA has classified PCBs as probable human carcinogens. Human studies show that acne-likerashes can occur in occupational exposures to PCBs. Other studies of occupational exposuresuggest that PCBs might cause liver cancer. Reproductive and developmental effects may resultfrom occupational exposure. It must be emphasized that these effects are not definitivelyproven(53).


The U.S. Department of Health and Human Services has determined that asbestos is a knowncarcinogen. Information on health effects of asbestos in humans comes from studies of workersexposed to high levels of asbestos in the workplace. Increased incidence of lung cancer andmesothelioma (a tumor of the lining of the lung and chest cavity) were seen in these workerstudies. Both types of cancer are usually fatal. These diseases develop over a period of years. There is also evidence that increased incidence of other cancers (e.g. stomach, intestines,esophagus, pancreas, kidneys), but this is less certain. Members of the public exposed to lowerlevels may be at increased risk for cancer, but the risk is usually small and difficult to verify. Exposure via inhalation also poses the risk of scarring of the lungs, termed asbestosis (a diseasecharacterized by deposits of fibers in the lung, causing difficulty in breathing). This disease causesdifficulty in breathing and decrease in blood flow in the lungs. Asbestosis is a serious illness, inmost cases resulting from exposure to high levels of asbestos via inhalation. There is littleevidence that exposure via consumption of asbestos results in negative health effects. (54)


Groundwater Contaminants at WSTA

Table 2: Groundwater Contaminants at WSTA
Total wells
ContaminantsContaminant Levels
ATSDR Comparison Value
Overburden Aquifer2,4 DNT8.5 20 chronic EMEG child
2,6 DNT5.1 400 intermediate EMEG child
1,3,5 TNB7.3 0.5 RMEG child
2,4,6 TNT1.0 - 12.0 1.0 CREG
cadmium22.02.0 CREG
Shallow Bedrock Aquifer2,4 DNT0.96 -1.0 20 chronic EMEG child
2,6 DNT0.34 - 3.8 400 intermediate EMEG child
2,4 DNB0.49 1.0 LTHA, CREG
nitrotoluene0.16 - 1.2 none
1,3,5 TNB0.13 - 2.5 0.5 RMEG child
2,4,6 TNT0.56 - 5.8 1.0 CREG
cadmium100.0 - 115.02.0 CREG
manganese10.0 - 420.050 ppb RMEG child
Deeper Bedrock Aquifer2,4,6 TNT0.19 - 12.0 1.0 CREG
cadmium 11.0 - 20.0 2.0 CREG

Comments on Weldon Spring Ordnance Works Public Health Assessment

The following responses were received during the public comment period. This list of commentsdoes not include editorial comments concerning word spellings, sentence syntax, etc. It does notinclude comments on accuracy of stated facts. If the accuracy of a statement was questioned, thestatement was verified or corrected. The portions of the comments below that are in parentheseswere paraphrased by ATSDR for brevity or clarity. If the same comments were received frommore than one source, only one comment and response is listed.

Comment 1: (Document) does not mention the WSOW public meeting hosted by the Corps ofEngineers on November 20, 1992. This was a significant meeting that alerted ATSDR to newcancer concerns not previously addresses.

    Site Visit section has been modified to reflect this comment.

Comment 2: (Demographic section) could more meaningfully say that population is sparse, older,and rural to the west of the site and dense, younger, and suburban to the east.

    PHA demographics section reflects information from the 1990 Census concerning population inthe area immediately surrounding the WSOW. While population density does increase to the east,toward St. Louis, the area of interest to this PHa is that of the immediate vicinity of WSOW.

Comment 3: The environmental pathways discussion ... does not mention the common regulatorconcern that rather than "Chemicals routinely manufactured, handled, and stored at WSOW", it istheir degradation products that are perhaps (italics added) more dangerous. In their number andvariety, degradation products are more difficult to study and assess.

    This PHA addresses contaminants determined to be present at WSOW based on data collected inthe Remedial Investigation process. Also evaluated are the potential for exposure of the public tothese chemicals. Where toxicological studies are not available on specific breakdown products,assumptions are made based on toxicological information available on the original chemicals,using conservative safety factors. Additionally, the potential for exposure of the public tobreakdown products is no more likely than it would be for the original chemicals. For thesereasons, this document assumes no more threat to the public health from breakdown productsthan from the original ordnance chemicals.

Comment 4: The "Report on Childhood Leukemia in St. Charles County" covered a period from1970 to 1983. Since the data may be over 25 years old, shouldn't more recent studies beselected? Have broader cancer studies specific to the area been undertaken?

    The study encompassed a period of 14 years, ending about 12 years ago. This is the most recentstudy available. To this time, no "broader" studies have been conducted.

Comment 5: Plans are now being finalized to combine the WSOW landfill into the WSSRAP cell.This will eliminate the need for two landfills to exist side-by-side with associated long-termmonitoring.

    Appendix D is based on ROD information available to ATSDR at the time of publication of this PHA. In the event that a combined landfill is authorized it will offer the advantages suggested by the comment.

Comment 6: On P. 17 reference is made to groundwater contamination by heavy metals. Inparticular cadmium is mentioned as found at elevated levels. This is substantiated in appendix Fwhere cadmium is clearly above ATSDR's CV's at all three aquifer levels. In the assessment ofhealth risks associated with possible onsite migration of contaminants in groundwater (P 26-27)no mention is made of heavy metals or cadmium in particular. Has cadmium been sampled for? Ifit was sampled for and was not detected at levels that pose a risk, this information warrantsinclusion in this section. If it has not been sampled for, what is ATSDR's position on this, basedupon the high levels found all three aquifer levels? No mention was made of cadmium's presenceor absence at the St Charles County Water Departments wells, just nitroaromatic compounds. Isthere monitoring information to resolve this informational void?

    We appreciate this being brought to our attention. Information from the WSOW Baseline RiskAssessment has been incorporated into the text. Samples from 53 offsite wells were analyzed forchemicals of potential concern, including cadmium. Two well contained cadmium at or above thedetection level. The maximum concentration found was 0.3 ppb, well below the ATSDR CV of2.0 ppb.

    The St. Charles County Well Field uses water from the Missouri River alluvial aquifer and is notlikely to be affected by contaminants in the aquifers under WSOW. According to informationprovided by WSOW, St. Charles County maintains a testing and treatment program for drinkingwater contamination, including metals such as cadmium. Levels measured at the wellfield arewithin the required EPA limits for cadmium in drinking water (less than 5.0 ppb) (55).

Comment 7: The third paragraph under the first page of conclusions concerning ATSDR'sopinion of the protective nature of a "properly designed and operated incinerator" seems a bitpremature in light of the qualifications expressed in the preceding sentence. It could also be saidthat a properly designed and improperly operated incinerator might not be protective of publichealth. I feel it is inappropriate at this early stage to be making a veiled endorsement of atechnology unless your agency can reference experience from other sites where this type oftechnique has been used on the same matrix of compounds. It may well be that this is the propertechnology from a public health perspective, However, there is very little in your document tosupport this assertion and any position on its desirability or non-desirability should therefore bestricken.

    ATSDR remains committed to the position that a properly designed and operated incinerator is asafe and effective method for remediating soil contamination of the type found at WSOW. Aslong as proper engineering and monitoring are maintained throughout the operation, thenitroaromatics can be destroyed without release of lead or other contaminants into theenvironment. State and federal regulators will be acting to ensure that operations are safelyconducted. Any reservations expressed in Appendix D relate to ATSDR's desire to provideexpert review and evaluation of the incinerator and operating plans prior to our final endorsement. As an advisory agency, ATSDR does not have the authority to approve or disapprove of theincineration program. However, both the EPA and state regulators have been completelyreceptive to our input at this site.

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