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PETITIONED PUBLIC HEALTH ASSESSMENT

CAROLINA SOLITE CORPORATION
(a/k/a CAROLINA SOLITE CORPORATION/AQUADALE)
AQUADALE, NORWOOD COUNTY, NORTH CAROLINA


SUMMARY

In August 1998, NC WARN (North Carolina Waste Awareness and Reduction Network)petitioned the Agency for Toxic Substances and Disease Registry (ATSDR) to conduct a publichealth assessment of the areas surrounding the Carolina Solite facility located in Aquadale, NorthCarolina. The petition was filed on behalf of area residents. Residents are concerned aboutadverse health effects they believe are the result of long term exposure to emissions from theSolite facility.

ATSDR reviewed all available environmental and health outcome data and concludes that thedata do not suggest a current threat to human health. Data reviewed for this and previousdocuments indicate that environmental media may contain chemical contamination, but belowlevels that have been associated with adverse health effects.

Based on all available data, ATSDR has made the following observations:

  • Air: Current ambient air contamination and particulate matter concentrations in the community are not a public health hazard. ATSDR was unable to assess healthimplications of past exposure because no historical environmental sampling data exist.

  • Soil and Sediment: Soil and sediment data do not indicate exposure to high levels of contamination.

INTRODUCTION

On August 8, 1998, the North Carolina Waste Awareness and Reduction Network (NC WARN)petitioned the Agency for Toxic Substances and Disease Registry (ATSDR) to conduct a publichealth assessment on the impact of industrial emissions from the Carolina Solite facility on arearesidents [1]. ATSDR reviewed and evaluated available data from the North CarolinaDepartment of Health and Human Services (NC DHHS) and the North Carolina Department ofEnvironment and Natural Resources (NC DENR). ATSDR evaluated community concerns andavailable air, groundwater, and biological data to determine the potential and extent of theexposure of residents to environmental contamination. The public comment release of that publichealth assessment was made available to the public for review in April 2001. This document is afollow-up health assessment reviewing air data from monitoring stations located in the vicinitysurrounding the Solite facility during 2000, and surface soil and sediment data collected by theUnited States Environmental Protection Agency (EPA) in summer of 2000. The purpose of thisdocument is to identify potential human exposures and to recommend appropriate public health follow-up activities for the newly collected data.


BACKGROUND

The Solite facility is located near Aquadale, North Carolina. Aquadale is approximately 45 mileseast of Charlotte. The property surrounding the facility is rural farmland and residential. Themost populated area is due east approximately five miles in the town of Aquadale. Maps of this area are located in Appendix A.

Solite began operating in Aquadale in 1953, producing lightweight aggregate for the constructionindustry. The facility is regulated as a boiler and industrial furnace (BIF) under state and federalhazardous waste laws and regulations. The facility produces lightweight aggregate by heatingslate and shale mined in an onsite quarry in four large rotary kilns. As the shale and slate areheated, gases are released causing them to expand. The expanded product, referred to as Solite®,is lightweight, fire resistant, weather resistant, and provides insulating properties [2]. It is used inconstruction for masonry rocks and concrete. The Solite facility primarily consists of a quarryfrom which shale and slate are extracted, an inactive quarry, a storage and handling area for theraw material, the rotary kiln process area, and product storage and handling areas [2]. The facilityencompasses approximately 125 acres [3].

In the past, Carolina Solite has used a number of fuels to fire its kilns. In Spring of 2000, thefacility began to use waste oil and coal exclusively in its heating process. From 1983 until 2000,the facility burned Hazardous Waste Derived Fuel (HWDF), waste oil, and coal to fire thefurnaces. Carolina Solite received the HWDF via a pipeline and trucks from Giant ResourceRecovery, a contiguous permitted liquid waste blending and storage facility [3].


DEMOGRAPHICS

Demographic information was collected in a five block group area surrounding the Solite facility. Current population estimates for this area are available for 1998 at the census block group levelonly [4]. The block groups in this area are predominantly Caucasian; approximately 90% of the5629 residents are Caucasian. African Americans account for 9.3% of the total population andabout 1% are of another race. Less than 1% of residents are of Hispanic origin. Median agevaries for these block groups (between 36.1-40.2), but average 38.4 years. The area appears to berelatively stable in that the median length of residence is 15.5 years, in contrast to the countywhich has a median length of residence of 13.8 years [4]. For further demographic information, see Appendix B.


COMMUNITY HEALTH CONCERNS

In the early 1990s, residents expressed their concerns to state authorities about potentialenvironmental contamination and human exposure from site emissions. The concerns includedthe incidence of different types of cancers, Alzheimer's Disease, asthma, sinus conditions, andneurological illnesses. Specific cancers of concern were: leukemia and brain, kidney, colon,lung, and skin cancers. To investigate residential concerns, NC DHHS and NC DENR collectedgroundwater, air, and biological data in 1999 and 2000. The US EPA collected soil and sedimentdata and the NC DENR continued to collect air data throughout 2000 to further characterizeenvironmental contamination in the properties surrounding the facility.


DISCUSSION

Methods

In preparing evaluations of environmental data, ATSDR uses established methodologies fordetermining how people may be exposed to potential contamination from surrounding industry,and what effects, if any, may result from exposure to those contaminants.The ways that peoplemay come into contact with chemical contaminants, called 'exposure pathways', are alsoevaluated. The exposure pathways that ATSDR evaluates include ingestion (eating), inhalation(breathing), and skin contact.

If one or more of the exposure pathways are established, ATSDR then considers whetherchemicals have been or still are present at levels that may be harmful to people. ATSDR firstdoes this by screening the concentration of contaminants detected in air, water, or soil againsttheir health-based comparison values. Comparison values (CVs) are based on animal studieswhen relevant human data are lacking (which is often the case). ATSDR's CVs are designed tobe orders of magnitude lower than levels known to produce adverse health effects. They arederived using conservative assumptions and ample safety factors designed to make themprotective of human health. Some CVs may be hundreds or thousands of times lower thanexposure levels shown to produce effects in laboratory animals or humans. Because of theseample safety margins, even chemicals detected above CVs would not necessarily be expected toproduce adverse health effects. To determine the public health implications of chemicals detectedabove CVs, a more detailed evaluation of site-specific exposure conditions is required.Regardless of the contamination level, a public health hazard can exist only if people come incontact with, or are otherwise exposed to, harmful levels of contaminated air, soil, or water.

If ATSDR has not established a CV for a chemical, then one developed by a different agency isused. If no CV of any kind is available for a chemical, then that chemical is further evaluated.For all site-related contaminants that are detected at levels above CVs, ATSDR reviews relevantscientific literature to determine if site-specific exposures could pose a hazard to public health.

For a complete discussion of these criteria (quality assurance considerations, human exposurepathway analyses, ATSDR's health comparison values, and the methods of selectingcontaminants above comparison values), refer to Appendix C.

Extent of Contamination

NC DENR provided ATSDR with air monitoring data collected throughout 2000. Also, ATSDRevaluated soil and sediment data on samples collected in 2000 by the EPA. This evaluation wasbased on the site-specific data provided to ATSDR for review, which are limited in scope by thetime period of the data collection and by the assumption that proper quality assurance/qualitycontrol standards were followed in analyzing laboratory results. Through air monitoring, arsenichas been identified by NC DHHS and ATSDR as a "contaminant of concern" at this site, whichmeans only that arsenic was detected at concentrations in excess of one or more CVs. (See Appendix C.)

Potential Exposure Pathways
Area residents may have come in contact with site-related contamination in one or more of the following ways:

  1. Previous or current inhalation of contaminated ambient air.

  2. Skin contact with, inhalation, and/or ingestion of contaminated surface soils.
  • Skin contact with and/or ingestion of contaminated sediment.

ATSDR evaluated human exposure to determine whether nearby residents are exposed tocontamination migrating from the site. An exposure pathway contains the following fiveelements: a source of contamination, transport through some kind of environmental medium (air,soil, or water), a point of exposure (a water well, or emissions stack), a route of exposure(breathing, eating, drinking), and an exposed population. In this assessment, ATSDR evaluatedchemicals in the air, soil, and sediment that people living in the nearby residences may breathe orcontact in some manner.

Air

Ambient air

Four air sampling monitors were located near the Solite Corporation site in 1999 by NC DENR, Division of Air Quality. Two additional monitors were located in the area in 2000, including a monitor that was not expected to be impacted by the facility. One of the 1999 monitors was removed in 2000. ATSDR addressed the 1999 data in the first health assessment for this site. This health assessment focuses on data collected in 2000. The initial sites were placed in maximum impact areas. These locations were determined by NC DENR using emissions modeling techniques.

The samples taken in 1999 were analyzed for heavy metals and particulate matter. Levelsreported in that monitoring effort are well below levels that have been observed to cause adversehealth effects. During 2000, NCDENR continued to characterize ambient air in the Solite vicinityto monitor emissions from the change in fuels which occurred in spring of 2000. ATSDR did notfind notable differences in trends in air concentrations of metals, nor were there notabledifferences in the concentrations of metals in air between 1999 results and 2000 results.Therefore, ATSDR does not expect adverse health effects to occur as a result of exposure tocontaminants measured in ambient air in this community. As in 1999, ATSDR identified arsenic,cadmium, and chromium as contaminants of concern at this site. These are the only metalsexceeding ATSDR comparison values in each sampling location in 2000 with the exception ofmanganese. Of all samples taken at all locations in 2000, manganese slightly exceeded theATSDR minimum risk level of 40 ng/m3 (nanograms per cubic meter of air) in a single sample atthe Hill site in March of 2000 (at 41.5 ng/m3). This metal did not exceed any health basedguidelines in 1999, and was not included as a contaminant of concern.

Particulates in Air

Air monitoring technology presently has the capability of monitoring air particles in a range ofsizes, measured in micrometers. PM10 refers to particulates that are 10 micrometers in diameteror less, and PM2.5 refers to dust particulates that are 2.5 micrometers in diameter or less. Totalsuspended particulates (TSP) refers to a particulate concentration of all sizes. The totalsuspended particulate procedure captures measurable particulates as small as 0.1 micrometers (40CFR50- Appendix B). EPA has established regulatory guidelines of particulate concentrationsthat are safe to breathe in ambient air. EPA had specific regulations for TSP of 150 µg/m3(micrograms per cubic meter) for 24-hour averages and 75 µg/m3 for annual averages, butdecided that more specific guidelines for the size of the particle was necessary. These guidelinesare given for both average 24-hour concentrations and for average annual concentrations. Inaddition, samples were collected for particulate matter equal to and less than 10 micrometers indiameter (PM10). The particulate sampling technique for collected PM10 is also published in theFederal Register (40 CFR50-Appendix J). Currently, EPA has established acceptable 24-houraverage concentration averages for PM10 of 150 µg/m3 and 50 µg/m3 for PM10 annualaverages. Acceptable PM2.5 regulations are currently being negotiated by EPA.

In 1999, particulate matter was sampled continuously for nine months at two locations, and24-hour averages were taken every six days during that time. TSP levels were recorded for theentire nine month period (January through mid-September) at two sampling sites, and PM10 wascollected from early summer through December at two sites. PM10 was collected for one year(through early summer 2000) at these locations. Levels of particulates were not found to beelevated above federal or state health based guidelines during these sampling periods. Oneexception was a monitor placed in close proximity to a dirt road, which was moved because theresults were believed to be skewed by dust from passing traffic.

In 2000, TSP was measured with all seven monitors. Three of the monitors collected data allyear, and the others collected samples approximately half the year. All of the daily TSP andPM10 results were below the previous EPA recommended levels of 150 µg/m3 (24-houraverage) for all locations. The averages of the monitors were within acceptable annual ranges of75 µg/m3 for total suspended particulates and 50 µg/m3 for PM10 [8]. See Appendix D, Table 2for particulate sampling data.

Surface Soil

On June 28 and 29, 2000 EPA Region 4, Science and Ecosystem Support Division (SESD)conducted a soil and sediment investigation in the property surrounding the Solite facility [5].NCDENR and EPA developed the protocol and residents, ATSDR, and other NCDHHS andNCDENR stakeholders provided input to modify the initially proposed protocol.

EPA collected 16 soil samples and 5 sediment samples for analysis in areas modeled to be in theprevalent wind direction from the facility, as well as in an area considered to be 'background' orthose not thought to be impacted by facility emissions. Background samples for soils includedsamples 01A-SF, 01B-SF, and 01C-SF, and background samples for sediment included SD-01and SD-05. EPA collected five sediment samples both upstream and downstream of the facility.Each soil sample was a five point composite, with one aliquot collected in the center and onecollected 50 feet in each direction from the center. The five sediment samples were taken both upand downstream from the facility. All samples were analyzed for total metals in the target analytelist (TAL), volatile and extractable organic compounds on the target compound list (TCL), as wellas pesticides, PCBs, and dioxins. See the map in Appendix E for soil sampling locations.

The maximum soil concentrations of several metals detected in this investigation slightlyexceeded EPA and ATSDR comparison values for children exhibiting pica behavior, including:arsenic, aluminum, antimony, barium, cadmium, iron, manganese, and vanadium. In the presentcontext, pica behavior is defined as the habitual (as opposed to incidental) consumption of non-food items, such as soil, dried paint, and clay. It is not to be confused with the habit of mosttoddlers of putting things into their mouths. True pica is an intermittent behavior that occurs infewer than 1% of children and, when it does occur, is usually exhibited only during the first fewyears of life.

Aluminum, antimony, barium, cadmium, manganese, and vanadium exceeded ATSDRenvironmental media evaluation guide (EMEG) and reference media evaluation guide (RMEG)for pica children, but not for children exhibiting normal behavior or adults. The maximum levelsdetected would require the ingestion of a large amount of soil to negatively impact the health of apica child. Soil samples 3A and 3B exceeded child EMEG and RMEG levels at 24 and 21 ppm,respectively, but no samples exceeded adult values. These samples were detected 50 feet north ofthe Solite property, collected in a wooded area not affected by farming practices.

In summary, two of the 16 soil samples exceeded child CVs, 16 exceeded pica child CVs, and nosamples exceeded adult health based guidelines. ATSDR has no comparison values for iron, thusATSDR used the EPA risk based concentration (RBC) to evaluate the data. The RBC is 23,000ppm, and is not specific to child or adult. Thirteen of the 16 soil samples exceeded the RBC. See Appendix E Table 5 for a summary of these results.

The combined concentration of dioxins and furans (in toxic equivalents or TEQs) for bothresidential soils and background soil samples exceeded the EPA risk based concentration (RBC)for TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin). The RBC for TCDD is 3.9 ng/kg. The TEQ forboth the background site (5.7 ng/kg) and residential soils (18.83 ng/kg) exceeded the RBC of 3.9ng/kg. These results are analyzed in the contaminants of concern and the public health implications section.

In order to put the contaminant concentrations of samples collected in the Solite area inperspective, ATSDR attempted to locate background samples for comparison other than thosecollected during the EPA analysis. The United States Geologic Survey (USGS) conducted soilsampling of the conterminous United States between 1961 and 1975, resulting in 1,318 samplingsites across the United States. In 1965, the USGS took samples in North Carolina. Nine of thesewere within 70 miles of a USGS sample taken in Stanly county [6]. ATSDR analyzed these metalsconcentrations, specifically those metals which were found to be elevated in the EPA analysis, inan effort to determine whether or not those elevated levels would be expected to naturally occur inthe geographic area of Stanly county. The county specific data for these locations are presented in Appendix E.

Comparison of 1965 USGS Stanly County area soil samples and 2000 EPA soil samples in Stanly County/NC (ppm)
Metal 1965 contaminant range 2000 contaminant range 1965 contaminant mean 2000 contaminant mean
aluminum50,000-100,0006500-28,00067,77713,037
antimonyN/A-1ND-2.40.22 2.4
*detected in one sample
arsenic1.2-183.3-245.929.26
barium100-70030-15034485.13
cadmiumnot sampledND-1.8not sampled0.55
iron20,000-70,00012,000-75,00045,55528,687.5
manganese150-500077-7701294396.7
vanadium70-15019-84135.532.3

These data, while incomplete, provide an estimate of normal ranges for the area. ATSDRevaluated the contaminants exceeding comparison values, which include: aluminum, arsenic,antimony, barium, cadmium, iron, manganese, and vanadium. The 1965 samples for Stanly countyand surrounding counties do not vary significantly from the analytical results gathered by EPA in2000. For example, arsenic in Stanly county was measured at 18 parts per million (ppm) in 1965,and had a maximum of 24 ppm in 2000. Aluminum levels in Stanly county in 1965 were almostdouble that of the highest levels detected in 2000, and barium was lower in Stanly county than allbut one of the USGS samples. Cadmium could not be compared because it was not analyzed inthe USGS samples. The Stanly county rates for iron, manganese, and vanadium did notsignificantly differ in regard to contaminant ranges from USGS samples, and 2000 mean valuesare well within the "normal" range for metals in Stanly and other North Carolina counties.

Sediment

Sediment samples 2, 3, and 4 were collected downstream of the facility. Sample 2D was aduplicate of downstream sample 2. Two 'control' samples (1 and 5) were collected upstream fromthe facility and its effluent discharges. See Table 4 in Appendix E for specific results of theselocations. Of the metals sampled in sediment, arsenic, aluminum, cadmium, manganese, andvanadium exceeded ATSDR EMEGs and RMEGs levels for children exhibiting pica behavior.Iron and lead do not have ATSDR CVs, so EPA RBCs were used to evaluate the data. Iron andlead exceeded their respective RBC in at least one sediment sample. Also, arsenic exceeded childhealth based guidelines. Only iron and lead exceeded the EPA risk based concentration (RBC)which include adult exposures. Since these sediment samples were collected from riverbeds,average ingestion exposure will be much closer to zero than to the defaults used to derive soilguidelines, i.e., 100, 200 and 5,000 mg/day for adults, children and pica children, respectively.

ATSDR was able to obtain sediment concentrations for 45 samples collected in Stanly county in1976 by the USGS during the National Uranium Research Evaluation (NURE). A comparison ofthese results compared to the 2000 EPA results are shown below [7]:

Comparison of 1976 NURE data with 2000 EPA sediment data, Stanly county
metal 1976 range
(ppm)
1976 average concentration (ppm) 2000 range
(ppm)
2000 average concentration (ppm)
aluminum 13,600-65,400 37,592 2300-16,000 10,017
arsenic1 6.5-10 7.5 2-70 23.16
cadmium2 BDL-<.050 <1 ND-1.4 0.52
iron 7100-75,600 32,263 20,000-94,000 35,833
lead 10-2587 77.8 11-1100 222.5
manganese 50-3560 873.95 280-5300 655
vanadium 20-320 80.8 13-68 36.1
1 Arsenic levels from NURE data was obtained from newest analysis of Stanly county rates by USGS, 2001; J.N. Grossman andA.E. Grosz, correspondence.
2 Cadmium levels were obtained in the same manner as arsenic levels; all USGS levels were reported to be lower than thedetection limit of the instrument used to measure concentrations.

In 2000, average concentration ranges of arsenic, iron, and lead exceeded those of the 1976samples that were collected by USGS. These metals also had higher mean concentration levels.However, the concentration ranges and mean levels are more reliable for the 1976 samples thanthe 2000 samples because they are based on 45 samples, whereas the 2000 sample data are basedon 6 samples (one of which is a duplicate). A single sample that is elevated far above othersamples taken may skew the analysis of results. Arsenic, iron, and lead had a single sample thatfar exceeded other sample concentrations for the same metals. No two of these elevated levelswere found in a single location. For example, the highest concentration of iron was found insediment sample 1 at 94,000 ppm; the next highest concentration was 31,000 ppm in sedimentsample 3, which is significantly lower. The same is true for lead, with the highest elevation at1100 ppm in sediment sample 4. The next highest concentration for lead was 170 ppm insediment sample 3, and the next was 29 ppm, and the remaining samples were below 29 ppm.These levels are significantly lower than the highest elevation of 1100 ppm. The highest arsenicconcentration measured in 2000 was 70 ppm in sediment sample 3, but the rest of the sampleswere measured at 34, 12, 11, 10, and 2 ppm. These data suggest that, while some samples containcontaminants at concentrations in excess of health based guidelines for soil, these samples are notrepresentative of concentrations in either sediment or soil at this site. In other words, the numberof other samples that are NOT elevated may be the more realistic contaminant concentrationscenario than those single samples that are elevated. Also, the location of the sample does notseem to have any direct bearing on whether or not it is elevated. Some of the elevated samples areupstream of the facility, and some are downstream. Some downstream samples are elevated, whileothers are not. See Table 4 in Appendix E for specific results by sampling location.

ATSDR contacted the North Carolina Geologic Survey (NCGS) and requested a review of thesediment data, specifically for those metals which exceeded ATSDR and EPA health basedguidelines. The NCGS concluded that aluminum, iron, manganese, vanadium, and zinc levels arenot significantly different from statewide levels [8]. The state has no current comparison data forarsenic and cadmium. NCGS found that one sample with an elevated concentration of leadsignificantly exceeded state averages. Data for the state of North Carolina is presented in the tableon the following page.

North Carolina Geologic Survey- state sediment data for identified contaminants of concern1
metal

mean2 standard deviation minimum maximum crustal abundance
aluminum 38,480 25,813 1,100 229,400 81,300
iron 30,636 29,077 2,500 358,100 50,000
manganese 762 892 20 11,620 950
lead 11 41 5 2,597 13
vanadium 78 88 10 1,570 70
zinc 24.4 23.8 2.5 774 70
1 Note: arsenic and cadmium were not included in this evaluation for the reasons mentioned in the preceding paragraph.
2 All values are ppm, or parts per million

The NCGS also commented on two potential limitations of the data. First, the number of sedimentsamples collected is too small to result in significant conclusions about sediment concentrations inthe area. Secondly, the particle grain sizes of the sediment samples collected during the EPAinvestigation were large which may make it difficult to directly correlate with other stream sediment geochemical data [8].

Public Health Implications

Contaminants of Concern

Arsenic

Arsenic was identified by NC DHHS and NC DENR as a contaminant of concern because of itselevation in community ambient air in 1999. Inhalation exposure to inorganic arsenic (primarilyarsenic trioxide dust in air at copper smelters) is, in multiple studies, associated with increasedrisks of lung cancer in occupational settings. However, scientific literature does not supportassociations between lung cancer and exposure to airborne arsenic in residential settings [9].

The lowest "lowest-adverse-effect-level" (LOAEL) for lung cancer reported in ATSDR'sToxicological Profile for Arsenic (Sept 2000) is 50 ug/m3 (ATSDR 2000; Jarup et al., 1999). It isbased on a study of workers chronically exposed at a Swiss smelter for periods ranging from 3months to 30 years. Since smoking was more common in this occupational cohort than in thegeneral population (as is generally the case), and the synergistic effect of smoking andoccupational inhalation of arsenic on lung cancer risk was not taken into account, the true LOAELfor lung cancer attributable to arsenic exposure alone is likely to be significantly higher than 50ug/m3. When confounding factors such as smoking have been taking into account, no statisticallysignificant increase of lung cancer has been observed at 50 ug/m3 [10]. Mean levels of arsenic inambient air in U.S. cities (0.02-0.03 ug/m3) are more than 1,000 times lower than the LOAEL, andthe levels detected in Stanly County were typically 10-100 times lower still.

The reason that all of these levels still exceed ATSDR's cancer risk evaluation guide (CREG) andEPA's cancer-based RBC is that the latter represent hypothetical 1-in-a-million risk levels derivedby making the assumption that no threshold exists for carcinogenic effects. In its 1986 Guidelinesfor Carcinogenic Risk Assessment, EPA was careful to point out that such risk estimates do notpredict the true risk which is "unknown and may be as low as zero." Thus, while cancer-basedCVs may be of some use as screening values, they are not practical as a single method forconducting an assessment of the public health implications of chemical exposures. See Appendix C for a definition of ATSDR comparison values.

Although serious health conditions can result from acute or long term exposure to arsenic,ATSDR does not expect adverse health conditions to result from the levels at which arsenic wasdetected in this community. Levels of arsenic detected in 2000 were slightly lower than, but didnot vary significantly from, those detected in 1999.

Based on its evaluation of the data, ATSDR concludes that concentrations of arsenic in theambient air near the Solite facility are not a threat to human health. Mean levels of arsenic inambient air in the United States usually range from 1 to 3 ng/m3 (nanograms per cubic meter) inremote areas and from 20 to 30 ng/m3 in urban or industrial areas. The average levels of arsenic inambient air at this site are consistent with those at remote locations of the U.S. and are more than10 times lower than those in urban areas. The highest level of arsenic detected in the airmonitoring effort around this site was 10.7 ng/m3 (nanograms per cubic meter), which is 14 ng/m3lower than the highest concentration detected in 1999 (24.7 ng/m3). However, the vast majority ofdetects were well below that level. For the general population, food is the primary source ofarsenic exposure; inhalation exposure is generally negligible by comparison [9].

Arsenic concentrations in soil range from 3.3-24 ppm, exceeding the conservative pica CVs in all16 samples taken and all 5 sediment samples (2-70 ppm). Levels for children were exceeded intwo soil samples and two sediment samples. The concentration of arsenic in soil is only slightlyelevated in both samples where it exceeded CVs for child exposure (21 and 24 ppm, respectively).It is highly unlikely that young children would be exposed to riverbed sediment. Since the safetyfactors built in to ATSDR's CVs make them lower than levels known to cause adverse healtheffects, none of the detected concentrations are expected to pose a hazard to public health. Thesame is true for sediment exposure for children, i.e., assuming that they are exposed at all tocontaminated sediment.

Cadmium

Cadmium was present at levels above health-based guidelines in ambient air approximately 9% ofthe time in 2000 as compared to one-third of the time in 1999. Concentrations ranged from 0.39 to0.95 ng/m3 (nanograms per cubic meter of air). Air cadmium levels are generally low in U.S.cities, ranging from 1 to 40 ng/m3 [11]. ATSDR's only CV for cadmium in air is a CREG of 0.6ng/m3 (For an explanation of the practical meaning of cancer-based health guidelines that arebelow background levels, see the previous section on arsenic.) The greatest sources of cadmiumexposure in humans are food and cigarette smoke. Cadmium is found in small amounts in fruitsand vegetables and in larger amounts in leafy vegetables and potatoes, shellfish, and meats. Milk,dairy products, eggs, beef, and fish usually contain <0.01 mg/kg (ppm) cadmium, while higherconcentrations, 0.01-0.10 mg/kg are typically found in vegetables, fruits, and grains.

Potatoes (average concentration of 0.0421) and leafy vegetables (av. 0.0328) have the highestconcentrations [11]. Although severe health effects can result from high exposure to cadmium, noadverse health effects are expected to result from exposure to concentrations found in theenvironmental media sampled in and around this facility.

Although frequently above the ATSDR CREG, levels of cadmium observed in the ambient air inthis community do not currently pose a threat to human health. While 17 of 183 samples exceededthe CREG, none of these exceeded any chronic NOAELs (no-observed-adverse-effect-levels), i.e.,levels at which no adverse health effects have been observed animals or humans [11]. The lowesthuman inhalation LOAEL listed in ATSDR's Toxicological Profile for Cadmium is 23 ug/m3 fora 9.2% incidence of proteinuria [12] (The NOAEL for the same effect was 30% lower, i.e., 17ug/m3). All of the detected concentrations at this site were from 3 to 6 orders of magnitude lowerthan this minimal human LOAEL.

Cadmium was present in soils at levels that ranged from non-detectable (ND) to 1.8 ppm.Cadmium concentrations in soil are highly variable, depending on the sources of minerals andorganic materials. While Eisler (1985) reports cadmium concentrations of 0.01-1 ppm in soils ofnonvolcanic origin, soils of volcanic origin like those in this area may have naturally occurringconcentrations of up to 4.5 ppm [13]. Some cadmium levels in soil at this site exceeded ATSDR'schronic pica child EMEG of 0.4 ppm, but none exceeded ATSDR's chronic EMEGs for children(10 ppm) or adults (100 ppm). The pica value for cadmium is based on a model-derived lifetimeNOAEL for renal effects that is 15 times lower than average dietary intake of cadmium (30ug/day) in the U.S. [11]. Nevertheless, the pica child chronic EMEG contains an additional safetyfactor of 10. ATSDR has determined that cadmium levels measured in this area do not pose athreat to human health for the following reasons: pica activity typically last for only the first fewyears of childhood, and not for a lifetime; a toddler's opportunity to be exposed to the more highlycontaminated soil/sediment samples is generally extremely limited; and the bioavailability ofcadmium in soil will generally be lower than that of cadmium in food.

Chromium

Total chromium exceeded the EPA RBC (0.16 ng/m3) in all but one air sampling effort of 1999,and all but 5 in 2000. Chromium occurs naturally in the environment and has several forms.Chromium III is found in vitamins, dietary supplements, food, water, and air and is an essentialnutrient for human survival. Chromium VI and chromium 0 are generally produced in industry.Chronic occupational exposure to high levels of chromium VI in air is associated with anincreased incidence of lung cancer. However, breathing in small amounts of chromium VI doesnot cause adverse health effects in most people.

Levels of chromium detected in ambient air surrounding this facility are not expected to result inadverse health effects. These levels, which ranged from 0.80-1.47 ng/m3 (nanograms per cubicmeter), were all well below ATSDR's intermediate Environmental Media Evaluation Guide(EMEG) or Minimum Risk Level (MRL) of 500 ng/m3 for particulate chromium VI. This EMEGwas derived by extrapolating from a less serious LOAEL of 0.05 mg/m3 to a benchmarkconcentration of 0.016 mg CrVI/m3 and dividing the latter by an uncertainty factor of 30 [14]. ATSDR's EMEGs are concentrations of substances in air, water, or soil derived from ATSDR'sMRLs from the same substances by assuming default rates of intake of the medium in question.ATSDR's MRLs are doses (typically expressed in mg/kg/day) that represent an estimate of dailyhuman exposure to a chemical that are unlikely to be associated with any appreciable risk ofadverse non-cancer effects over a specified duration of exposure.

Many of the levels measured in this community slightly exceeded the ATSDR CREG (0.08ng/m3). To evaluate the potential effect this may have on area residents, ATSDR reviewed theavailable scientific literature regarding inhalation exposure and cancer. The lowest concentrationof chromium that has produced cancer in humans (the CEL or cancer effect level) from inhalationexposure in scientific studies is 0.413 mg/m3 or 413,000 ng/m3 [14]. Generally these levels arederived from occupational studies. ATSDR does not expect any adverse health effects to occur inthis community as a result of chromium exposure.

Dioxins/Furans

Toxic Equivalency Factors (TEFs) are estimates of the toxicity of dioxin-like compounds relativeto the toxicity of 2,3,7,8-TCDD, the most toxic form of dioxin, which is assigned a TEF of 1.0.All other forms (congeners) of dioxin and furan (except 1,2,3,7,8-PeCDD) have lower TEFvalues ranging from 0.00001 to 0.5. Calculating the toxic equivalency (TEQ) of a mixtureinvolves multiplying the concentration of individual congeners by their respective TEF. The sumof the TEQ concentrations for the individual congeners is the TEQ concentration for the mixture.

Dioxins and furans were tested in all soil and sediment samples. The TEQ values from the dioxin analyses ranged from 1.8 ng/kg to 12 ng/kg in soils and 0.31 ng/kg to 15 ng/kg for sediment samples. The highest levels detected in soil and sediment slightly exceed ATSDR's chronic EMEG for pica children (2 ng/kg), but not for non-pica children (50 ng/kg) or adults (700 ng/kg). These levels did not exceed any of ATSDR's EMEGs for intermediate exposure durations (2 weeks to a year). Even if pica children did ingest the most heavily contaminated soils and sediments detected, they would not do so either exclusively or chronically. But, even if they did, it would be physically impossible for them to ingest enough soil or sediment to get a potentially toxic dose of dioxin-like compounds.

Based on the data currently available for this site, exposure to toxicologically significant levels ofdioxins and furans in soil or sediment is not possible; levels measured by EPA do not represent a public health risk.

Other contaminants exceeding ATSDR CVs

Of all other contaminants, the following also exceeded comparison values in at least one soilsample: aluminum; antimony; barium; iron; manganese; and vanadium. With the exception ofiron, the maximum detected concentration of all the aforementioned contaminants exceeded onlyATSDR's pica child CVs. ATSDR has no CVs for iron, an essential nutrient, but most detectedconcentrations exceeded EPA's RBC of 23,000 ppm. However, iron does not represent a healththreat to residents for the following reasons: the safety factors built into the exceeded CVs makethem hundreds or thousands of times lower than levels that produce health effects; it is veryunlikely that pica children will be exposed frequently (if ever) to the most highly contaminatedsoils identified; and many of these minerals, including iron, are naturally occurring in this area,and are common, even essential, components of a normal diet. ATSDR concludes that none of themetals detected in soil at this site pose any hazard to the health of anyone who might be exposedto them.

As pointed out earlier, ATSDR has no CVs specific for sediment and, therefore, uses its soil CVsto screen sediments as well. The reader should keep in mind that, since the defaults used in thedevelopment of soil CVs do not apply to sediments, this practice introduces additional safetyfactors into the evaluation. In sediment, the following contaminants exceeded ATSDR's soil CVsin at least one of the five samples: aluminum, iron, lead, manganese, and vanadium. Aluminum,manganese, and vanadium exceeded pica values only. ATSDR does not have specific comparisonvalues for iron or lead, but the concentrations detected in sediments exceeded EPA soil RBCs inthree of five samples of iron, and one of five samples of lead. Iron was detected at its highestconcentration (94,000 ppm) at the background site, which is up stream of the facility as well as upstream from facility effluent discharges. Other levels were detected far below the backgroundlevel.

The maximum lead level detected in sediment (1100 ppm) was approximately 2.75 times higherthan EPA's Interim Soil Lead Guidance Level of 400 ppm. Lead was detected in low quantities inair, but all detected levels were 3 orders of magnitude below the NAAQS quarterly average of 1.5ug/m3. Although the sediment sample (04-SD) of lead with the lead elevation was down gradientof the facility, it does not necessarily follow that the facility is the source of the lead deposit.Another sample (03-SD), which was also down gradient of the facility, but was upstream of theelevated sample (i.e., closer to the facility), did not exceed the EPA RBC for lead. Thus, in and ofitself, the single sediment sample from the 2000 monitoring event that contained elevated leadlevels does not constitute a public health hazard.

Metal concentrations in air are not a threat to human health at this time. Although several metalsexceeded some ATSDR and EPA CVs in soil and sediment, site-specific exposures would beinsufficient to result in any adverse health effects in any members of the community, includingpica children. Nevertheless, parents should discourage their children from ingesting soils andclay in yards and in streams.

ATSDR Child Health Initiative

Children are at greater risk than adults for certain kinds of exposure to hazardous substancesemitted from waste sites and emergency events. They are more likely to be exposed for several reasons:

  • The developing systems of children can sustain damage if toxic exposures occur duringcertain growth stages.
  • Children play outside more than adults, and therefore have an increased likelihood ofcoming into contact with chemicals in the environment.
  • Since they are typically shorter than adults, children breathe more dust, soil, and heavy vapors close to the ground.
  • Children are also smaller, resulting in relatively higher doses of chemical exposure per body weight.

Therefore, ATSDR evaluated the types and quantities of chemicals detected in the air, soil, andsediment in the community to determine how children might be exposed and whether levelsdetected in the community could be associated with any reproductive or developmental effects.

While there are children living in this community, they generally do not have access to the Solitesite. During site visits, ATSDR staff did not note any points of access for children to the plantproperty. ATSDR closely reviewed possible exposure situations for children while evaluating thissite (for example, air exposure, trespassing, and soil in the community playground). In itsevaluation, ATSDR used the Environmental Media Evaluation Guidelines for children (EMEGs),who are considered the most sensitive segment of the population. EMEGs are estimates of dailyhuman exposure to a chemical that is unlikely to produce non-cancer health effects over a specificduration of time.

Although children could be exposed to the measured concentrations, it is unlikely that theexposure would be of significant enough duration or at high enough concentrations to adverselyeffect their health. See Appendix C for further explanation of comparison values used by ATSDR in this health assessment.

Physical Hazards

Access to Carolina Solite Corporation is restricted by fences. ATSDR has not received anyinformation suggesting that children have access or have had access to the property. Trucksregularly enter and exit the property and may pose traffic hazards to playing children andresidents. Trucks are hosed off at the property line to prevent off-site contamination from dust and soils that may accumulate on truck bodies and tires while on facility property.


CONCLUSION

Data collected in 1999 and 2000 do not indicate the existence of a health hazard for residentsliving near the Carolina Solite facility.

Based on data provided for this public health assessment, ATSDR concludes the following:

  • Air: Arsenic, cadmium, and chromium levels are not expected to result in adverse health effects.

  • Soil: Although some metals exceed pica child values, they are not expected to causeadverse health effects in children under site-specific conditions of exposure. No metalsexceeded ATSDR CVs for adults or non-pica children.

  • Sediment: Most iron and some lead levels exceeded available comparison values, but were not high enough to pose a health hazard under site-specific conditions of exposure.

Best Public Health Practice

Parents may choose to discourage their children from ingesting soils and clay in yards and sediment.


RECOMMENDATIONS

None


PUBLIC HEALTH ACTION PLAN

Completed Activities:

  • The North Carolina Department of Environment and Natural Resources (NC DENR),Division of Air Quality located six air sampling monitors on the perimeter of the Soliteproperty and a background monitor approximately six miles from the Solite property.Contaminant concentrations of priority pollutants were monitored for two years.

  • NC DENR conducted spot soil and groundwater sampling of various areas of the CarolinaSolite facility in the early 1990s, and groundwater sampling of residential wells in 1999.

  • NC DENR, Division of Air Quality monitored total suspended particulates and metals inair from January 1999-December of 2000.

  • EPA sampled and sediment on residential properties and rivers and streams in the vicinity of the Solite plant.

  • In Spring 2000, the North Carolina Department of Health and Human Services (NCDHHS) Occupational and Environmental Epidemiology staff conducted a survey ofcommunity residents around the Solite facility.

  • EPA analyzed soil samples taken in the Summer of 2000, and submitted results to NCDENR, NC DHHS, and ATSDR.

  • In July of 2000, NC DHHS Occupational and Environmental Epidemiology staff evaluatedambient air data collected in the breathing space of the Carolina Solite facility.

  • ATSDR held a public availability session in Abermarle on Monday, July 30, 2001 between6 pm and 8 pm. This meeting gave residents an opportunity to come and voice concerns,ask questions, and be briefed by state and federal partners about the sampling that has been conducted in the community living near the Solite facility.

Future Activities:

  • ATSDR will address any comments received about this public health assessment byresidents, state officials, and other stakeholders.

  • ATSDR will continue to give technical support, as needed, to NC DENR and NC DHHS.

SITE TEAM/AUTHORS

Prepared by:

Michelle A. Colledge, M.P.H.
Environmental Health Scientist
Petitions Response Section
Exposure Investigation and Consultation Branch
Division of Health Assessment and Consultation

Frank Schnell, Ph.D.
Toxicologist
Petitions Response Section
Exposure Investigation and Consultation Branch
Division of Health Assessment and Consultation

Reviewed by:

Benjamin Moore
Regional Representative
Office of Regional Operations
ATSDR Region 4

Donald Joe, P.E.
Section Chief
Petitions Response Section
Exposure Investigation and Consultation Branch
Division of Health Assessment and Consultation

John E. Abraham, Ph.D., M.P.H.
Branch Chief
Exposure Investigation and Consultation Branch
Division of Health Assessment and Consultation


REFERENCES

  1. North Carolina Waste Awareness and Reduction Network. Petition letter to ATSDR.Atlanta. August 8, 1998.

  2. RCRA Facility Assessment of Carolina Solite Corporation and Oldover Corporation.Submitted by A.T. Kearney, Inc. to The U.S. Environmental Protection Agency. EPAContract Number 68-W9-0040, work assignment number R04-23-03. September 1992.

  3. Sampling and analysis plan for soil, sediment, and air monitoring near Solite Corporation in Stanly County. North Carolina Department of Health and Human Services, March 2000.

  4. Claritas, Inc. 1999 Population and Housing Estimates. 1999. Claritas, Inc: Arlington, VA.

  5. Soil/Sediment Sampling Investigation Report- Aquadale Community, Stanly County,North Carolina. November, 2000. United States Environmental Protection Agency.Science and Ecosystem Support Division. Enforcement and Investigation Branch.

  6. Boerngen, Josephine G., and Shacklette, Hansford T., 1981, Chemical Analyses of Soilsand Other Surficial Materials of the Conterminous United States: U.S. Geological SurveyOpen-File Report 81-197, U.S. Geological Survey, Denver, CO.

  7. Smith, S.M., 2000, National Geochemical Database: Reformatted data from the National Uranium Resource Evaluation (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) Program, Version 1.20: U.S. Geological Survey Open-File Report 97-492. Accessed July 2001.

  8. Reid, J.C. Report of Investigation: review of stream sediment geochemical analyses forsites in Stanly County, North Carolina. North Carolina Geological Survey, May 29, 2001.

  9. Agency for Toxic Substances and Disease Registry. Toxicological profile for arsenic. U.S. Department of Health and Human Services. April 1993. Update. Report No. TP-92-02


  10. Welch, A.C., et. al. 1982. Arsenic exposure, smoking, and respiratory cancer in coppersmelter workers. Archives of Environmental Health, 37(6):325-335.

  11. Agency for Toxic Substances and Disease Registry. Toxicological profile for cadmium.U.S. Department of Health and Human Services. Update, 1999.

  12. Jarup, L. et. al. 1988 Cumulative blood-cadmium and tubular proteinuria: A dose-responserelationship. Archives of Occupational Environmental Health, 60:223-229.

  13. Eisler, R. 1985. Cadmium hazards to fish, wildlife, and invertebrates: A synoptic view.U.S. Fish and Wildlife Service, Biology Reports, 85 (1.2) 1-46.

  14. Agency for Toxic Substances and Disease Registry. Toxicological profile for cadmium.U.S. Department of Health and Human Services. Update, 2000.

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