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ATSDR uses a conservative approach to assess whether levels of environmental contaminationmight indicate a past, present, or future health hazard. The following paragraphs first describe thisassessment methodology, then apply the methodology to the Virginia Solite facility.

In this section, ATSDR evaluates whether people were or continue to be exposed to airbornecontaminants originating from Virginia Solite at levels that might pose a health hazard. ATSDRmakes this determination first by identifying exposure pathways, or the ways in which chemicalsmay enter a person's body. Elements of an exposure pathway that, if present, might lead to humanexposure include a source of contamination, a contaminated environmental medium (e.g., air orwater), a point of human exposure, a route of exposure (e.g., ingestion, inhalation, or skin contact),and a receptor population [10]. If exposure was or is possible, ATSDR then considers whethercontamination is present at levels that might affect public health.

ATSDR then uses comparison values and findings from recent scientific studies to determinewhether the environmental monitoring data indicate a public health hazard. Comparison values areconcentrations of chemicals that the current public health literature suggest are nontoxic.Comparison values are not thresholds of toxicity and concentrations greater than the comparisonvalues may or may not cause health effects among exposed populations. A description ofcomparison values used by ATSDR is provided in Appendix C.

In its public health assessments, ATSDR uses comparison values to identify chemicals that requirefurther evaluation. More specifically, if a chemical is never found at levels exceeding itscorresponding comparison value, ATSDR considers the levels of contamination for that chemical tobe nontoxic. If, however, a chemical is found in the environment at levels exceeding itscorresponding comparison value, ATSDR designates the chemical as a chemical of concern andexamines potential exposures to environmental contamination in greater detail. Because ATSDRuses conservative assumptions to derive its comparison values, the presence of concentrationsgreater than comparison values does not necessarily suggest that health effects will occur.

The following analyses use comparison values to identify the air pollutants discharged from Solite atconcentrations that are nontoxic as well as to identify the air pollutants that require furtherevaluation.

A. Air Exposure Pathway

To determine whether people living or working in the communities surrounding a site have beenexposed to chemicals released by that facility, ATSDR health scientists evaluate the environmentaland human components leading to human exposure. The process by which people have been, arebeing, or will be exposed to chemical substances is called an exposure pathway. An exposurepathway has five elements [10]:

  • A source of pollution (point of original release of a chemical substance or perhaps apolluted medium at or near the point of exposure, if the original source is unknown);
  • Polluted environmental medium (at or near a point of exposure--the mechanism by whichchemical substances may be transported and transformed); environmental media include air,soil, and water;
  • Point of exposure (location, structure, or device by which people contact a chemicalsubstance);
  • Route of exposure (means by which a chemical substance enters the body [e.g., breathing,eating, or touching]; and
  • Population at or near the point of exposure.

If all five elements exist and people have been, are being, or probably will be exposed, healthscientists consider the exposure pathway completed. A completed exposure pathway does notnecessarily indicate a public health problem. If one (or more) of the elements is missing butinformation suggests that it (they) could exist, health scientists consider the exposure pathwaypotential. If one (or more) of the elements is missing and could never exist, health scientists mayeliminate the suspected pathway from further consideration.

ATSDR did not identify completed human exposure pathways for the Virginia Solite site. Arearesidents and on-site workers may be exposed to contaminants in ambient air as they are emitted intothe environment. Table 2 identifies potential human exposure pathways for the Virginia Solitefacility. Due to the lack of emission data prior to 1991 and the lack of ambient air monitoring data,past human exposures are unknown.

Other potential human exposure pathways may exist for this site (e.g., food chain pathways, etc). However, for the purposes of this public health assessment ATSDR will only consider the air pathway because it seems most relevant to community health concerns. However, ATSDR will reevaluate human exposure pathways as new information becomes available for this site.

Table 1.

Exposure Pathway Elements Time
Source Environmental Medium Point of Exposure Route of Exposure Exposed Population
Virginia Solite Ambient Air On-site




B. Environmental Data Evaluation


After identifying a potential exposure pathway, ATSDR health scientists review environmental datato see how much chemical pollution is in an area, where the pollution is, and how people contact it.ATSDR does not generally collect its own environmental data but reviews information provided bythe EPA, other government bodies (e.g., federal, state, and/or local), industry, and the public.ATSDR assumes that the party gathering the data followed adequate quality assurance and qualitycontrol measures with regard to chain-of-custody, laboratory procedures, and data reporting. Thus,the validity of the conclusions in an agency report depends on the completeness and reliability of thereferenced information. Data about which ATSDR has concerns are identified in the discussion of anagency report. Also, in cases where environmental data are limited, ATSDR usually indicates whatadditional data are needed.

After reviewing available environmental data, chemicals are selected for further discussion orevaluation. The following factors receive consideration:

  • Concentrations of chemical substances found in the environment or other evidence of release.
  • Field data quality, laboratory data quality, and sample design.
  • Community health concerns.
  • Comparisons of chemical concentrations in the environment with ATSDR comparisonvalues for noncancer and cancer outcomes; and
  • Other factors, including, evidences of carcinogenicity, absences of an appropriatecomparison value, exposure to multiple chemical substances, interactive effects, fate andtransport, and health outcome data.

Any of these listed factors may support the identification of a chemical substance as a chemical ofconcern (COC), but the interpretation and evaluation of the factors depend on current scientificknowledge, public health policies, and professional judgment.

Comparison values are media-specific (air, soil, water) concentrations calculated from varioushealth guidelines designed to protect public health. These values are not legally enforceable but areused as a screening criterion to select chemicals for further public health evaluation. The fact that achemical substance is selected and discussed as a COC does not mean site-specific exposure to thechemical substance will result in adverse health effects. However, such a chemical substance willreceive additional public health evaluation in subsequent sections of an ATSDR report. Appendix Ccontains discussions of ATSDR health guidelines and comparison values used in data tables in thispublic health assessment.

If a chemical concentration level exceeds a specified comparison value, it is a COC. In addition, thechemical may be designated as a COC if it is classified as a carcinogen or potential carcinogen bythe following organizations: (1) the National Toxicology Program (NTP) in the Department ofHealth and Human Services (DHHS), (2) the International Agency for Research on Cancer (IARC),or (3) the EPA. Cancer Risk Evaluation Guides (CREGs) and Environmental Media EvaluationGuides (EMEGs) are the first choice for a comparison value. If a CREG or EMEG is not available,a Reference Dose Media Evaluation Guide (RMEG) will be chosen for the comparison value. Whenchemicals do not have comparison values, scientific literature is used in the selection of thesechemicals as COCs.

Because comparison values do not represent thresholds of toxicity, chemical concentrations abovecomparison values do not necessarily mean that adverse health effects are going to occur. In fact,ATSDR comparison values are designed to be orders of magnitude lower than levels at which noadverse health effects were observed in experimental animal and/or epidemiological human studies,making them very protective of public health.

Environmental Data Evaluated for Virginia Solite

When evaluating health concerns associated with inhalation of contaminated air, ATSDR prefers tomake conclusions and recommendations based on results from ambient air monitoring studies, orstudies that test the air that residents actually breathe. In cases where no ambient air monitoring dataare available, such as in the vicinity of Solite, ATSDR examines emissions data to give additionalperspective to evaluating public health concerns. Emissions data characterize the rate andconcentration at which stacks release pollutants into the atmosphere. However, ATSDR was unableto review all of the available emission data for this public health assessment. ATSDR will evaluatethese data at a later time.

Virginia Solite is currently operating under interim status (BIF rule), which means that the facilitywas in existence on or before August 21, 1991, and must have submitted a Part A permit applicationby this date [11]. Until EPA issues a final permit, wherein facility-specific permit conditions areestablished through a trial burn, owners/operators of interim status facilities must ensure compliancewith emission standards by showing certification of precompliance and certification of compliance.

Under the BIF rule, Solite is required to comply with strict air emissions standards to ensureadequate protection of human health and the environment. These standards are divided into fourcontaminant categories: organics, particulate matter, metals, and hydrogen chloride (HCl) andchlorine (Cl2) [11].

    Virginia Solite Precompliance Activities

In order to certify precompliance, Virginia Solite established operating conditions under which itwould meet emissions standards. As part of precompliance activities, Solite:

  • estimated uncontrolled emissions of particulate matter, metals, hydrogen chloride, andchlorine gas,
  • estimated controlled emissions of particulate matter, metals, and chlorine gas,
  • used site-specific air quality modeling to determine emission levels for metals, hydrogenchloride, and chlorine gas, and
  • compared controlled emissions with the emission limits to demonstrate compliance [12].

Solite conducted these activities to establish hazardous waste derived (HWD) fuel rates andcharacteristics, kiln feed rates, and kiln production rates to ensure precompliance with the BIFregulations.

    Virginia Solite 1992 Stack Emission Testing

Table 3 presents data from Virginia Solite's June 1992 stack emission test to demonstratecompliance with RCRA for carbon monoxide, particulate matter, metals, hydrogen chloride, andchlorine emissions as part of the RCRA process [13]. Emission testing was conducted on kilns 2 and4 only [5]. Measured stack emission rates were below permit limits for all contaminants. Thefollowing contaminants were detected at least once during the three runs performed: antimony,arsenic, cadmium, chromium, hexavalent chromium, and lead. Because contaminants weremeasured at the stack, they are not an accurate description of actual human exposure levels. Due tostack height, distance to a potential receptor population, and the mixing of the stack emissions withambient air, the level of contaminants that could potentially be inhaled would be greatly reduced.

It should be noted that emission tests provide only a "snapshot" of actual emission rates over the long term. A total of three, 3-hour tests were performed during the 1992 RCRA compliance emission test. Similarly, three runs were performed during the 1993 dioxin and furan testing. Because of this, the emission tests can only be used to confirm that Virginia Solite releases these constituents into the air, but these tests do not provide enough information to evaluate human exposure to emissions over time. EPA believes that the combination of feed rate and operating limits imposed under the Certification of Compliance will ensure that the "snapshot" measured during the stack test will be a representative, but conservative, estimate of emissions during normal operations. However, Solite Corporation believes that emissions testing is not representative of normal operations since emissions measured during the compliance test are a combination of: 1) worst case fuel and raw material feed rates, 2) worst case, spiked, waste fuel metal feed rates, 3) worst case temperature conditions, and 4) worst case baghouse differential pressure conditions. Due to these uncertainties, ATSDR prefers to evaluate ambient air data in its public health assessment process.

Table 3.

Constituent Units Kiln No. 2 Kiln No. 4 Kilns 2 & 4
Measured1 Measured1 Allowable2
Particulate Matter Grains per dry standard cubic foot (gr/dscf), corrected to 7% oxygen. 0.004 0.01 0.08
Hydrogen Chloride Grams per hour (g/hr) 27,100 30,600 81,072
Chlorine g/hr 617 548 2,448
Antimony g/hr <0.0583 0.081 3,477.2
Arsenic g/hr 0.112 0.107 8.59
Barium g/hr <0.598 <0.432 579,032.8
Beryllium g/hr <0.028 <0.025 6.23
Cadmium g/hr 2.72 0.899 21.29
Total Chromium g/hr <0.422 <0.050 not applicable
Hexavalent Chromium g/hr <0.038 <0.067 2.11
Lead g/hr <4.887 6.149 1,042.26
Mercury g/hr <0.228 <0.153 926.45
Silver g/hr <0.438 <0.087 34,741.97
Thallium g/hr <0.027 <0.024 5,790.33
Carbon Monoxide parts per million (ppm)4 58.8 90.1 100
Total Hydrocarbons ppm4 4.81 3.29 20
1Average of three test runs.
2Based on Tier III dispersion modeling.
3 "<" indicates that the constituent was not detected; the numerical value is the instrument's detection limit
4Continuous 60-minute rolling average corrected to 7% oxygen.

    Virginia Solite 1993 Stack Emission Testing for Dioxins and Furans

In 1993, Virginia Solite voluntarily performed stationary source sampling for dioxin and furanemissions from the stack at kiln 1 [14]. The purpose of the test program was to evaluate a "typical"lightweight aggregate kiln's dioxin and furan emissions while maximizing chlorine input to the kilnthrough the controlled introduction of 1,2,4-trichlorobenzene (TCB) and tetrachloroethylene (Perc)[14]. In addition to dioxin and furan emission measurements, Solite conducted stack gas analysis onthe principal organic hazardous constituents (POHCs) in order to calculate destruction and removalefficiency.

The results of the stack test indicate no detectable emissions of 2,3,7,8-TCDD, the most potent ofthe dioxins and furans, but other dioxins and furans were detected. Using information developedfrom precompliance certification air quality modeling, ATSDR calculated an off-site estimatedambient air concentration for dioxins and furans. The calculated level of dioxin and furans werebelow EPA risk based ambient air concentrations. However, this information represents an estimatefor a single kiln. Please refer to Appendix E for additional information about dioxins and furans.

    Compliance Certification Activities

In May 1995, Solite conducted compliance testing, as required by the BIF rule, to verify theoperating conditions at the facility. In August 1995, Solite submitted a certification of compliancecontaining operating conditions based on the results of the testing. The certification included adescription of any changes that had taken place since the previous compliance certification, as wellas the test data and results of quality assurance and quality control work. Throughout the remainderof interim status, Solite is required to retest every three years and update their certification based onthe test results. EPA region III has granted Solite a one-year extension (until August 1999) of thenext recertification to allow Solite to combine their recertification testing and risk assessment testinginto a single series of stack tests. Emission levels will change to reflect operating conditionsapplicable at the time of testing.

In Table 4, ATSDR presents estimated ambient air concentrations of constituents at the maximumexposed individual (MEI) locations (Figure 4). These estimates were calculated from the stackemission data (an average of three tests for each kiln) collected by Solite during compliancecertification for kilns 1 through 4 (Measured column, Table 4). These levels represent themaximum allowable emissions for each kiln.

ATSDR utilized the dilution factor (0.4029 micrograms per cubic meter per gram per second) calculated by Solite during its air quality modeling to convert the average stack emission data (ingrams per hour, g/hr) for each kiln into an estimated ambient air concentration at the MEI location. This was necessary so that ATSDR could compare the estimated ambient air concentrations toATSDR air comparison values.

In addition to screening the estimated ambient air data for each kiln against ATSDR comparisonvalues, ATSDR summed the values for each data set in the Measured column for kilns 2, 3, and 4and presented it in the Sum: Kilns 2,3,&4 column in Table 4. ATSDR summed these data setsbecause Solite operates three kilns at any given time and reserves one kiln as a backup. Thecombined data for kilns 2, 3, and 4 allow ATSDR to screen the combined effect of the three kilnsagainst ATSDR comparison values; please note, the information in the Sum: Kilns 2,3,&4 column ispresented for comparison purposes only and does not represent permitted allowable emissions forSolite. ATSDR elected to use the data for kilns 2, 3, and 4 because the data for kilns 1 and 2 are identical.

Using the average stack emission data for each kiln (Table 4, the columns labeled Measured forkilns 1 through 4), the estimated ambient air concentrations at the MEI locations for all constituentsare below ATSDR comparison values. ATSDR does not have a comparison value for totalchromium; however, Solite was able to determine the amount of hexavalent chromium (the mosttoxic for of chromium) that is the fraction of the total chromium value. Therefore, ATSDR is ableto screen the amount of hexavalent chromium against its comparison value.

It is important for the reader to note that:

  • While this represents the worst case scenario for facility emissions, Solite has computer-driven controls that calculate emissions on an hourly rolling average and willautomatically cut off the feed fuel if emissions reach 90% of the maximum allowableemission rates.
  • Based on Solite's modeling data, the MEI locations are identified by two points just north of Solite's northern fenceline (Figure 4). While it cannot be assumed that these two points account for all human exposure, ATSDR wanted to evaluate this area further to determine if persons were living there who may be exposed to contaminants from the Solite facility. To do this, ATSDR obtained the census block data for the area that contained the MEI locations. According to 1990 census data for this area, 5 individuals live within this census block [9]; however, the census block for this area is as large as the Solite facility and is not specific as to where individuals in this area live. Therefore, ATSDR obtained satellite imagery of this area and determined that no buildings were present in this area.

Table 4.

Constituent Kiln No. 1 [15] Kiln No. 2 [16] Kiln No. 3 [17] Kiln No. 4 [18] Sum3:
Kilns 2, 3, & 4
Comparison Value
Hydrogen Chloride 1.62 1.62 1.23 1.82 4.67 21 EPA Region III Risk Based Concentration
Chlorine 0.0022 0.0022 0.00056 0.0026 0.0053 370 EPA Region III Risk Based Concentration
Antimony 0.0000040 0.0000040 0.0000041 0.0000069 0.000015 1.5 EPA Region III Risk Based Concentration
Arsenic 0.0000062 0.0000062 0.000019 0.000058 0.000083 0.0002 CREG
Barium 0.00020 0.00019 0.000017 0.00021 0.00042 50 EPA Reference Concentration
Beryllium 0.00000078 0.00000078 0.0000022 0.000011 0.000014 0.0004 CREG
Cadmium 0.0000087 0.0000087 0.000020 0.00012 0.00015 0.0009 EPA Region III Risk Based Concentration
Total Chromium 0.000034 0.000034 0.000033 0.00025 0.00031   none
Hexavalent Chromium 0.0000060 0.0000060 0.00000090 0.0000053 0.000012 0.00008
Chronic EMEG
Lead 0.000057 0.000057 0.00024 0.00094 0.0012 1.5 National Ambient Air Quality Standards
Mercury 0.000022 0.000022 0.000011 0.000011 0.000044 0.2 Chronic EMEG
Silver 0.0000041 0.0000041 0.0000017 0.0000025 0.0000083 18 EPA Region III Risk Based Concentration
Thallium 0.0000038 0.0000038 0.0000041 0.0000039 0.000012 0.5 EPA Reference Concentration
1Average of three stack emissions for each kiln.
2Value for hexavalent chromium.
3These data do not represent permitted limits for Virginia Solite

Please note, that each kiln has its own separate stack therefore the emissions of each kiln will not all impact the same location at this maximum level.

C. Health Outcome Data

Government agencies routinely collect information on the health of the populations within different geographic areas. Many state health departments have developed registries of illnesses and diseases. Some county and local health departments also routinely or periodically collect health information. Concerned community members and community action groups may also collect health information in particular areas of interest. ATSDR reviews this information to evaluate whether certain health outcomes are occurring at elevated rates in certain areas.

Community members reportedly identified more than 100 cases of cancer and lupus in Cascade,Virginia, and nearby Eden, North Carolina. The incidence of disease reportedly occurred in greaterconcentration to the north-northeast of the facility. Winds at Solite predominantly come from thenortheast and the southwest and south-southwest (Figure 5). Due to public concern, cancer studieswere performed in Cascade, Virginia and three communities to the southwest of Virginia Solite,including Eden, North Carolina.

A Cancer Cluster Investigation in Cascade, Virginia, was performed by the Danville HealthDepartment and published on July 17, 1996 [19]. This study resulted from community complaintsvoiced about the Solite facility during public hearings held by the Board of Supervisors. Due to lackof available data from the cancer incidence registry, the study used death certificate data todetermine cancer rates for Cascade. The study found no increased mortality for any types of cancerin Cascade. The Danville Health Department will update this report annually for the next five yearsas new death certificate data are received.

Additional cancer studies were performed in North Carolina. In 1996, the North Carolina CentralCancer Registry studied cancer incidence for the previous 4-year period for the communities ofRuffin and Pelham [20]. These communities are located to the southeast of the facility. The studydid not identify any unusual or unexpected patterns in the number of new cancer cases. Furthermore,the cancer incidence rates for Ruffin and Pelham was not higher than expected in comparison to the remainder of the state.

In response to complaints by community members that the town of Eden, North Carolina was a moreappropriate location for a study than Ruffin and Pelham, the Central Cancer Registry performed asecond cancer incidence study [21]. Eden, one of the two largest towns in Rockingham County, islocated southwest of Virginia Solite. Age-adjusted rates for cancer from all causes were calculatedfor Eden using incident cases from 1990 through 1993. This study identified a lower number of totalcancers than expected in Eden in comparison to North Carolina as a whole.

A faculty member at the Virginia Commonwealth University, Center for Environmental Studies, hasbegun gathering environmental data from VADEQ regarding emissions from Virginia Solite. Thesedata will be considered for the performance of a study designed to evaluate community concerns,health outcomes from exposure to chronic, low-level emissions from the facility, and ecologicalendpoints associated with emissions from Solite.

No studies of lupus or respiratory disease were identified for the areas surrounding Virginia Solite. Since Lupus and most respiratory diseases are not reportable health conditions, state healthdatabases do not normally track these health conditions.

D. Public Health Implications and Community Health Concerns Evaluation

The petitioners are concerned about air emissions from the facility and the perceived high incidenceof cancer, lupus, and respiratory illness (asthma and emphysema) in their community [1].


Based on the available environmental data and modeling, the available health outcome data, andinformation about the facility operations, ATSDR does not believe that there is a plausible linkbetween the development of cancer and human exposure to site-related contaminants from theVirginia Solite facility.

Systemic Lupus Erythematous (SLE)

ATSDR does not believe that there is a plausible linkbetween community health concerns related to thedevelopment of systemic lupus erythematous, commonlycalled lupus, resulting from human exposure to site-related contaminants from the Virginia Solite facility.

The exact cause of lupus is unknown; however, thescientific literature does not indicate a link betweenhuman exposure to chromium and the development oflupus.

In lupus, the body produces abnormal antibodies thatreact to a person's own tissues. Lupus can affect thecentral nervous system and several organs of the body,including the heart, lungs, and kidneys. The disease canmimic several individual illnesses: it may, for instance,cause skin rashes, arthritis, anemia, seizures, orpsychiatric illnesses [22].

The 1982 Revised Criteria for the Classification of Systemic Lupus ErythematousLupus is a chronic multisystem inflammatory disorderwith various clinical presentations. Symptoms of lupusrange from mild to threatening. Many of the symptoms oflupus are non-specific, and many are shared with otherdiseases. To define the disease better, the AmericanRheumatism Association revised the criteria for lupus in1982. In previous years, the accepted definition of lupusvaried among doctors and researchers across the country, causing problems with study comparisons. Today, patients are considered to have lupus if they have four or more of the eleven accepted criteria [23].

The cause(s) of the disease (etiology) remain undefined, but is likely to be multifactorial withgenetic, hormonal, and environmental/lifestyle influences [23]. One study reported having a familyof connective tissue disease as the strongest risk factor for development of lupus [24]. However, astrong association with the use of hair dyes containing aromatic amines was also reported for thesame study population [25].

Respiratory Illnesses

As previously discussed, if the Solite facility operated three kilns at their maximum allowableemission rate (a hypothetical worst case scenario), the resulting estimated ambient air concentrationfor all constituents are below ATSDR comparison values. At this time, ATSDR is unable todetermine if there is a plausible link between the community's health concerns related to respiratoryillness and human exposure to site-related contaminants.


E. ATSDR's Child Health Initiative

ATSDR recognizes that infants and children may be more vulnerable to exposures than adults incommunities faced with contamination of their air, water, soil, or food [26]. This vulnerability is aresult of the following factors:

  • Children are more likely to play outdoors and bring food into contaminated areas.

  • Children are shorter, resulting in a greater likelihood to breathe dust, soil, and heavy vapors close to the ground.

  • Children are smaller, resulting in higher doses of chemical exposure per body weight.

  • The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages.

Because children depend completely on adults for risk identification and management decisions,ATSDR is committed to evaluating their special interests for the Virginia Solite facility, as part ofthe ATSDR Child Health Initiative.

Children who are the most likely to be exposed to environmental media at the Virginia Solite facility site include the children living in nearby homes.

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