PETITIONED PUBLIC HEALTH ASSESSMENT
CALDWELL SYSTEMS INCORPORATED
LENOIR, CALDWELL COUNTY, NORTH CAROLINA
ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
The tables in Appendix B list contaminants of concern at the CSI site (Tables 1-5). ATSDR has evaluated those contaminants in subsequent sections of this public health assessment to determine whether exposure to them has public health significance. In this section, ATSDR selects and discusses contaminants using the following information: concentrations of contaminants on and off site; field and laboratory data quality and sample design; comparison of on- and off-site contaminant concentrations with ATSDR health comparison values for noncancer outcomes and cancer; and community health concerns.
In the data tables in Appendix B, listing of a contaminant does not mean that adverse health effects will result from exposures. Rather, the lists indicate contaminants that will be evaluated further in this public health assessment. Once a contaminant has been identified in one medium, that contaminant's concentrations in other environmental media will be reported, if the contaminant is found at a concentration above the detection limit of analysis.
ATSDR health comparison values are contaminant concentrations in specific media used to select contaminants for further evaluation. Those values include environmental media evaluation guides (EMEGs), which are based on ATSDR minimal risk levels (MRLs) and factor in body weight and ingestion rates; cancer risk evaluation guides (CREGs), and other relevant guidelines. CREGs are estimated contaminant concentrations that would be expected to cause no more than one excess cancer in a million persons exposed over a lifetime. CREGs are calculated from EPA's cancer slope factors. The RfDCs are media concentrations calculated from EPA's oral reference dose (RfD). The RfD is an estimate of the daily exposure to a contaminant that is unlikely to cause adverse health effects. EPA's drinking water health goals include the maximum contaminant level goal (MCLG) and the proposed maximum contaminant level goal (PMCLG). Maximum contaminant levels (MCLs) are contaminant concentrations that EPA deems protective of public health (considering the availability and economics of water treatment technology) over a lifetime (70 years) at an exposure rate of 2 liters of water per day. As stated previously, these health comparison values are used only to determine contaminants that need further evaluation. Issues related to exposures and health effects are discussed elsewhere in this public health assessment.
To identify possible facilities that could contribute to the air, groundwater, and surface water contamination near CSI, ATSDR searched the 1987 and 1988 Toxic Chemical Release Inventory (TRI). TRI was developed by EPA from the chemical release (air, water, and soil) information provided by certain industries (e.g., furniture). TRI did not contain information on toxic chemical releases within a 1-mile radius of CSI.
As discussed in the Background section, CSI accepted and incinerated waste materials from the furniture manufacturing industry and the U.S. Navy (torpedo fuel, Otto Fuel II). The spent torpedo fuel consisted of up to 10% of the CSI incinerator waste stream. It has been reported that Otto Fuel II, as used in torpedoes, contains propylene glycol dinitrate (76%), di-N-butyl sebacate (22.5%), and 2-dinitrophenylamine (1.5%). In the spent or waste torpedo fuel, cyanide may be present in concentrations up to 0.1%. Appendix B contains a list of wastes received, stored, and treated by CSI. Untreated wastes were removed from the site after CSI was ordered to stop operations (1).
Environmental samples were taken on site by EPA and the State of North Carolina (1987-1990). Analysis of those environmental samples indicates that hazardous substances are present in the on-site surface soil, subsurface soil, and groundwater. Tables 1 through 5 in Appendix B list the contaminants of concern found at CSI.
Air
No incinerator stack sampling or air monitoring was conducted that would be representative of emissions that occurred during the operational life of the incinerator (1976-1989). In addition, the incinerator has been removed from the site. Therefore, ATSDR was unable to determine what hazardous substances may have been discharged into the air when CSI was operating.
Groundwater
Groundwater samples were taken from the four permanent monitoring wells on site. The greatest groundwater contamination (see Table 1, Appendix B) was found in samples taken from the southernmost monitoring well (1).
Because CSI handled and incinerated Otto Fuel II, EPA analyzed one groundwater sample for the three Otto Fuel indicators: propylene glycol dinitrate, 2-dinitrophenylamine, and di-N-butyl sebacate. The sample did not contain the Otto Fuel indicators at or above detectable levels (1). The groundwater did contain levels of some volatile organic compounds (1,2-dichloroethane, 1,1-dichloroethene, 1,1,1-trichloroethane) that exceeded comparison values.
As part of the EPA investigation, on-site soil samples and groundwater samples were analyzed for dioxins and furans. Part of a family of 210 related chemicals, dioxins and furans are impurities created during the manufacture of certain herbicides and germicides and during the incineration of municipal and industrial wastes. No dioxins or furans were found at or above levels of health concern (1,5,6).
Soils
Polychlorinated biphenyls (PCB) were detected in surface soil (48,000 ppb) and subsurface soil (620 ppb) samples in one area of the property (Table 2, Appendix B). PCBs were below the analytical detection limits at all other soil-sampling locations (1).
The highest surface-soil (460,000 ppb) and subsurface-soil (430,000 ppb) lead contamination was detected in the same samples that contained PCBs (Table 2, Appendix B). Lead was detected in the other surface- and subsurface-soil samples at levels similar to background (natural) conditions (1).
Because CSI handled and incinerated Otto Fuel II, EPA analyzed three subsurface soil samples and two surface soil samples for the three Otto Fuel indicators: propylene glycol dinitrate, 2-dinitrophenylamine, and di-n-butyl sebacate. None of the samples contained the Otto Fuel indicators at or above detectable levels (1).
As part of the EPA investigation, on-site soil samples were analyzed for dioxins/furans. No dioxins/furans were found at or above levels of health concern (1,5,6).
Wastes
During the 1990 EPA investigation, liquids were found in the three sumps on site: ash tank, horizontal tank, and tank farm. Samples were taken from each of the sumps. Only lead was detected at a level of concern (Table 3, Appendix B). The highest concentrations for both compounds were found in the sample taken from the tank farm sump (1).
Environmental samples were taken off site by EPA and the State of North Carolina (1987-1990). Analysis of those samples indicates that hazardous substances are present in the off-site surface water and groundwater. Tables 4 and 5 in Appendix B list the contaminants of concern in the area near CSI.
Soils
Lead was the only contaminant detected in off-site surface and subsurface soil samples that was also identified as a contaminant of concern on site. The analysis of off-site soil samples did not detect any non-site-related compounds at levels of health concern. The amount of lead detected in off-site subsurface soils was at or below natural background levels (22,000 ppb). Only one off-site surface soil sample contained lead above background levels. That sample was obtained near a residence in the Mount Herman subdivision; lead was estimated at 57,000 ppb in that one sample (1). The lead detected in that sample probably reflects natural conditions because it is an estimated value that is still within the range of naturally occurring background levels.
As part of the EPA investigation (1990), off-site surface soil samples were analyzed for dioxins/furans and Otto Fuel indicators. Surface-soil samples were taken at locations near local residences and at locations identified by an EPA air dispersion model. The model was used to determine what areas near CSI were most likely affected during the operating life of the incincerator. None of the surface-soil samples contained dioxins/furans at or above levels of health concern (1 ppb total toxicity equivalency factor for dioxins/furans) (1,5,6). In addition, none of the surface soil samples tested contained Otto Fuel indicators above detection limits (1).
Groundwater
The only site-related contaminants detected in groundwater off site were found in the former Haas Dairy Farm well (Table 2, Appendix B). Two volatile organic compounds (1,2-dichloroethane and 1,1-dichloroethene) exceeded comparison values. Analysis of other residential well samples did not find contaminants at levels of health concern.
As part of the EPA investigation (1990), off-site groundwater samples were analyzed for dioxins/furans and Otto Fuel indicators. No dioxins/furans or Otto Fuel indicators were found in the groundwater samples above detection limits.
Surface Water
Surface water samples taken from the Haas Dairy Farm springs by EPA and by the State of North Carolina contained volatile organic compounds (1,2-dichloroethane, 1,1-dichloroethene, 1,1,1-trichloroethane, and lead); however, none of them exceeded comparison values (Table 5, Appendix B).
Biota
In September 1987, samples of leaves were collected by the State of North Carolina from selected oak and tulip poplar trees at four locations in Caldwell, Burke, and Davie counties. That sampling was conducted because of reports of vegetation damage and an unusual amount of particulate deposit on leaves in areas near the CSI incinerator. A sample taken from the Mount Herman subdivision contained 133,000 ppb lead (1). Interpretations of or conclusions from the analytical results are difficult to make because analysis of four samples from within such a large area is not statistically valid, and deposits were found only on some trees. In addition, surface soil samples taken near CSI did not contain levels of lead significantly above natural levels.
A member of the community collected samples of the material that was deposited on leaves near CSI. Analysis of the material by an independent laboratory showed it contained 2.6 ppb tetrachloro-dibenzodioxin. The specific congener (i.e., which one of 210 related dioxin and furans) was not identified. Therefore, it is not possible to determine the significance of that one sample analysis.
C. Quality Assurance and Quality Control
ATSDR was provided with quality assurance and quality control (QA/QC) information concerning the EPA investigations. The information indicates that appropriate QA/QC procedures were followed during EPA's sampling and analysis.
No QA/QC information was provided concerning the State of North Carolina investigations. The conclusions in this public health assessment are based in part on the data developed by the State of North Carolina. The validity of the conclusions, therefore, depend on the accuracy and reliability of the data provided.
The cistern with the standing water was the only physical hazard noted during the ATSDR site visits. Trespassers or workers could fall into the cistern and suffer physical injury.
To determine whether on-site workers, their families, and off-site residents are exposed to contaminants migrating from the site, ATSDR evaluated the environmental and human components leading to human exposure. That pathways analysis consists of five elements: a source of contamination; transport through an environmental medium; a point of exposure; a route of human exposure; and an exposed population.
ATSDR classifies exposure pathways as completed or potential. For a completed pathway to exist, five elements must be present, and there must be evidence that exposure to a contaminant has occurred, is occurring, or will occur. In the case of a potential pathway, at least one of the five elements is missing, but could exist. Potential pathways suggest that exposure to a contaminant could have occurred, could be occurring, or could occur. A pathway is eliminated when at least one of the five elements is missing and will never be present. Table 6 in Appendix B identifies completed exposure pathways at the CSI site; Table 7 identifies potential exposure pathways; and Table 8 identifies the eliminated pathways. The discussion following the tables addresses only the pathways important and relevant to the site.
A. Completed Exposure Pathways
Workplace Exposure Pathway
When interviewed by ATSDR, former employees of CSI reported they received little or no training about the potential toxic nature of the materials they handled. Because of alleged improper or nonexistent safety procedures, the workers believe they were routinely exposed to hazardous materials. Given the range of materials handled at the facility and the lack of industrial hygiene monitoring data, it is difficult to determine precisely what the former employees of CSI may have been exposed to. However, ATSDR believes that work practices and conditions known to have existed at CSI may have led to adverse health effects resulting from dermal contact with, and ingestion and inhalation of, hazardous materials (2).
Exposures of Family Members of Former CSI Employees
Interviews conducted by ATSDR indicate that former employees sometimes wore their work clothes home. Because of poor work practices, the work clothes were very likely contaminated with waste material handled at CSI. The families of former CSI employees may have been exposed to CSI-related hazardous materials via dermal contact with the contaminated work clothes; inhalation of hazardous materials that evaporated from the contaminated work clothes; and ingestion of hazardous materials that may have transferred from the clothes to the hands and then to the mouths of family members (e.g., young children).
Incinerator Air Emissions and Nearby Resident Exposures
According to a state report, an air pollution control system that consisted of two parallel bag filters to control particulate emissions from the incinerator and of carbon adsorption modules to control evaporative losses from the storage tanks was installed in 1987. Before 1987, CSI had no air pollution control systems. Citizens have reported heavy smoke being discharged to the air from CSI. State reports note that vegetation in areas immediately around the site received significant damage. The State attributes the damage to hydrogen chloride compounds discharged by the CSI incinerator that were deposited on the flora. In addition, analysis of particulate deposits on leaves found lead at concentrations as high as 133,000 ppb. No incinerator stack sampling or air monitoring was conducted that would be representative of the emissions that occurred over the operational life of the incinerator (1976-1989). Therefore, it is not possible to determine accurately what hazardous substances may have been discharged into the air when CSI was operating.
On the night of September 13, 1989, a fire at CSI involving a roll-off box of waste lacquer solids forced the evacuation of approximately 250 area residents. Area hospitals treated 54 persons for respiratory ailments. An area physician reported to ATSDR that he is aware of 14 current cases of reactive airway disease in residents surrounding CSI (2).
Therefore, it is very likely that residents surrounding CSI have inhaled hazardous substances (particulate and chemical) that were discharged into the air. Nearby residents are also likely to have had dermal contact with hazardous substances that were deposited on environmental surfaces and to have ingested hazardous substances that may have been deposited on foodstuffs.
Former Haas Dairy Farm Residential Well
Analysis of environmental samples taken from the residential well at the former Haas Dairy Farm detected volatile organic compounds above comparison values. Approximately four individuals used the well for drinking water and ingested those contaminants. In addition, people may have been exposed to the contaminants via skin contact (bathing) and inhalation (showering, when 1,2-dichloroethane and 1,1-dichloroethene are prone to vaporizing). Chronic exposures to the contaminants probably occurred; however, it is not possible to determine the duration of exposure because the extent of groundwater contamination is not currently known. The residential well at the farm is no longer being used for household purposes.
B. Potential Exposure Pathways
Future Groundwater Migration into Residential Wells
Groundwater beneath the facility exists under water-table conditions and resides in an unconfined aquifer system that includes the upper soil layers (silty clays, clayey silts, sandy silts, and silty sands) and the interconnected network of faults and fractures of the lower crystalline rock. Depth to groundwater beneath the facility ranges from 51 to 87 feet below land surface. Analysis of a water-table contour map developed by EPA indicates that CSI is situated over a groundwater divide. Therefore, the groundwater beneath the facility could migrate in two directions, east and west (1).
Analysis of groundwater samples on and off site indicates that the groundwater is contaminated with site-related contaminants. The only contaminated drinking water well is at the former Haas Dairy Farm (see previous discussion). None of the other residential wells sampled were contaminated. Existing groundwater contamination will continue to migrate east and west. At this time, it is not possible to determine the extent of off-site groundwater contamination. Additional monitoring wells are needed to better characterize the groundwater contamination (e.g., total distance traveled, direction).
Additional drinking water wells could in the future become contaminated with CSI-related hazardous substances. The estimated population receiving drinking water from private wells and the Joyceton municipal wells is 1,464 individuals within 4 miles of CSI. The nearest potable water well is approximately 1,900 feet southwest of CSI. People could be exposed to potentially contaminated groundwater via ingestion; dermal contact during bathing and showering; and inhalation while showering. At this time, without additional groundwater investigations, it is not possible to predict which residential wells are in danger of becoming contaminated.
On-Site Contaminants Pathway
As indicated in the On-Site Contamination section, the surface and subsurface soils near the bulk waste roll-off container area are contaminated with PCBs and lead at levels of public health concern (see Table 2, Appendix B). Individuals on site could have physical contact (skin) with the contaminants and inhale or ingest them as dust particles. However, access to CSI is restricted by a fence with a locked gate with a guard present at the entrance to the landfill. Those factors limit the opportunity for unauthorized entrance to the site. The authorized visits should be of short duration. Therefore, human exposure is likely not to be significant. In addition, standard dust control and personal protection procedures should prevent remedial workers from being exposed to the contaminants.
The liquids in the old tank farm sump are contaminated with 1,1,1-trichloroethane and lead. However, only lead (25 ppb) was found at concentrations above health comparison values. Individuals trespassing onto CSI could ingest the liquids by accident. However, such an occurrence would be incidental. It is unlikely that trespassers or workers would ingest on-site wastes chronically.
Other Potential Exposure Pathways
The springs at the former Haas Dairy Farm are contaminated with volatile organic compounds (1,2-dichloroethane and 1,1-dichloroethene) at higher concentrations than the residential well (see Table 5, Appendix B). Lead was not found above detection limits (2 ppb) in either spring; 1,1,1-trichloroethane was detected (<2-31 ppb) in the springs at various sampling times (1987 and 1990). The springs may have been used to water dairy cattle; however, ATSDR does not believe that the springs were used by people for drinking water. None of the chemicals detected in the springs were detected in milk from the cattle (2). Therefore, people are not likely to be exposed to the identified contaminants except for incidental ingestion of the spring water (e.g., during recreational activities such as wading in the spring).
Eliminated Pathway
As discussed in the Demographics, Land Use, and Natural Resource Use section of this public
health assessment, runoff (water and sediment) from CSI could enter the Upper Little River and
Gunpowder Creek. In addition, the two springs at the former Haas Dairy Farm eventually enter
Gunpowder Creek. Both the Upper Little River and Gunpowder Creek are used for some
recreational fishing. Therefore, it is possible that fish in the Upper Little River and Gunpowder
Creek could bioaccumulate CSI site-related contaminants. However, it is more likely that the
contaminants detected in surface water (1,2-dichloroethane, 1,1-dichloroethene, and 1,1,1-trichloroethane) would evaporate out of the surface waters before the contaminants would be
bioaccumulated. In addition, analysis of on- and off-site surface soil samples indicate a discrete
area of contamination --the bulk waste roll-off container area -- that has not migrated off site.
Therefore, it is unlikely that fish in the Upper Little River and Gunpowder Creek would contain CSI site-related contaminants at levels of public health concern.
The pathways analysis indicates that the CSI site has three major completed pathways: 1) inhalation, ingestion, and dermal absorption of materials in the waste stream by workers and their family members; 2) inhalation, ingestion, and dermal absorption of particulate and other emissions by residents living near the facility; and 3) ingestion of contaminated drinking water by individuals using the Haas Dairy Farm residential well. It is not possible from the information available to determine the duration and dosage of the exposures; therefore, the types of compounds in the waste stream are discussed generally.
Exposure Pathways of Workers and Families of Workers
To date, ATSDR has concluded that five of approximately 60 to 80 former employees of CSI have medically documented health problems that may have been caused by exposure to wastes handled at CSI (2). Health problems documented by physicians in Lenoir, North Carolina, and at Duke University, the University of North Carolina, and the University of California at San Francisco include toxic encephalopathy, dermatitis, respiratory complaints, arthritic complaints, chest pain, and transient elevations of liver function tests. Toxic encephalopathy includes tremors and balance difficulty (implying cerebellar dysfunction), short-term memory loss, behavioral changes, headache, and autonomic dysfunction (sweating and swings in blood pressure, temperature, and heart rate). Two of the former employees have progressive deterioration of central nervous system functions, despite stopping work at CSI. The ATSDR review of the toxicology literature for substances alleged to have been handled by CSI workers found that some of the substances possess neurotoxic properties (2). The effects that would be expected in the workers, and, to a lesser extent, in their families, would be expected to be primarily neurologic.
The following discussion outlines the types of effects that have been reported in the literature following exposures similar to those seen at the CSI facility. Although there are no good data on the exact chemicals identified in the CSI waste stream, a large part of the waste stream was made up of solvents used in the local furniture industry. The effects of solvent exposure have been widely studied, and a variety of organ systems are known to be affected. The most commonly reported effects have been neurologic and psychological. Various studies have reported electrophysiologic changes in individuals who have had significant exposure to solvents. In one study, changes in the electroencephalogram, which measures brain waves, remained in some subjects for 3 to 9 years after diagnosis (7). Another study that investigated objective measures of sensory and cognitive impairments suggested the presence of minor dysfunction of the nervous system, potentiated by alcohol. That study also noted mild impairments in attention processes (8). Studies of painters exposed to solvents indicate that they have an elevated risk of disability because of neuropsychiatric dysfunction (9,10). Studies of abusers of volatile substances such as solvents have produced good evidence that neuropsychiatric impairment is often found in individuals with definite neurologic abnormalities. However, the studies have too many shortcomings to draw any conclusions about individuals without neurologic abnormalities (11,12). Case reports of intoxication from occupational exposure to solvents are numerous. Headaches, dizziness, and nausea are commonly seen following low-level exposures. At higher levels (>7000 mg/m3), there are reports of stupor, paresis, and amnesia (16,17).
Studies of the reproductive effects of solvent exposure have had conflicting results. Studies in Scandinavia have suggested menstrual effects (14) and an increased risk of spontaneous abortion (13) in women who worked in dry-cleaning establishments. A large study by Wrensch et al (1990) of women potentially exposed to solvent-contaminated water did not find an increase in adverse pregnancy outcomes. One study investigating the effect of methylene chloride exposure on birth weight did not demonstrate any significant adverse effects (18). The syndrome toluene embryopathy has been described in the children of women who abused volatile substances during pregnancy. Those children have microcephaly (small brain), central nervous system dysfunction, developmental delay, and limb anomalies (19).
Occupational case reports have noted hepatitis in workers exposed to solvents. One report described severe liver damage with associated hemolytic anemia and clotting problems (20,21).
From evidence in animals, several solvents are believed to be human carcinogens. Evidence from animal studies of the carcinogenicity of solvents in people is not as well established for solvents other than benzene. Studies of dry cleaners have found some evidence that tetrachloro-ethylene is a carcinogen (22).
Approximately 10% of the waste stream at CSI was naval torpedo fuel (Otto fuel II). The major component of Otto fuel is the propellant, propylene glycol dinitrate (PGDN) (76%). A study of the biodegradation of propylene glycol dinitrate found it was more volatile than believed (23). Individuals exposed to PGDN have reported a spectrum of symptoms, including headache, nasal congestion, dizziness, eye irritation, and loss of consciousness (28). The headaches described by exposed CSI workers are similar to the headaches described by many explosives workers (24). The headaches are caused by the vasodilating effects of organic nitrates (25). A study of workers with occupational exposure to PGDN reported one case of increased incidence of angina pectoris. The study had several limitations, but produced findings that should be investigated further (26). PGDN is similar to other nitrate esters in that it induces formation of methemoglobin -- a transformed hemoglobin molecule in the blood. When methemoglobin is formed, the blood cells' ability to transfer oxygen to the tissues is reduced (27). A few studies in animals and people have shown that exposure to PGDN affected balance and motor performance (30,28,29). The studies used neurophysiologic testing to detect subtle neurologic effects of exposure. Additional studies need to be done to address the question of long-term neurologic effects. Effects that would be expected in exposed CSI workers and, to a lesser extent, in their families, are primarily neurologic.
Residents in the community surrounding the facility were exposed to particulate and other components of smoke from the stack emissions (completed pathway). Members of the community near CSI would be expected to have had primarily respiratory exposure to emissions from the incinerator. The following is a review of the literature on the effects of residential exposures to releases of particulate and sulfur dioxide emissions from incinerators and factories. A 1983 review by Ericsson and Camner of the health effects of sulfur oxides and particulate in ambient air indicated that there was a dose-response relationship between sulfur dioxide and respiratory effects. They noted that no clear effect on lung function had been seen in studies of human exposure to levels below 2.9 mg/m3. Above that level, individuals in the study complained of nasal congestion and irritation. As the levels increased, the researchers noted an increase in the respiratory rate and bronchoconstriction (tightening of the lung passages similar to that seen in asthmatics) (32).
One study that investigated respiratory disease associated with the reopening of a steel mill in a community found an association between the levels of particulates and hospital admissions for pneumonia, pleurisy, bronchitis, and asthma (33). Information from the National Health and Nutrition Examination Survey II (NHANES II) has been used to examine the relationship between air pollution and lung function. NHANES II was conducted from 1976 to 1980; 20,322 people were examined during the survey. Spirometric measures (measure of lung function following exhalation into a machine that measures the rate and volume of the air) were obtained on a subsample of 4,300 people aged 6 to 24 years. Information on annual air pollution in the communities was obtained by monitoring stations that measured sulfur dioxide, nitrogen dioxide, ozone, and total suspended particulate. One study examining those parameters found an association between the total particulate levels and a decrease in respiratory function (34). It should be noted that studies linking lung cancer to air pollution have often not controlled for cigarette smoking, making the findings uncertain (37).
Although the studies discussed here are not analogous to the situation at CSI, there are many similarities in the types of products of incomplete combustion that may have been released from CSI and the types of emissions described in the literature. The studies indicated that respiratory effects are possible outcomes of exposures to emissions from an incinerator.
The levels of 1,2-dichloroethane and 1,1-dichloroethene seen in the Haas Farm well are far below the levels at which adverse health effects have been seen; the current lead level in the well is just below the current action level recommended by EPA. Children are more sensitive to the effects of lead exposure than adults. The central nervous system is the primary target organ for lead toxicity in children (40,41,42), and the effects of childhood exposure may persist into adulthood (43). Current information indicates that disturbances in neurobehavioral development can occur in children with blood lead levels in the range of 10 to 20 µg/dL and in children whose mothers had blood lead levels in that range during pregnancy (44). Lead levels in children appear to be related to the level of lead contamination in their environment (45). Experimental studies relating blood lead levels to dietary lead intake in adults produced estimates of a 0.02 µg/dL increase in blood lead for each microgram of lead ingested per day (46). Estimates of human exposure to lead from the well are far below one microgram of exposure each day; therefore, a significant increase in the blood lead levels of those ingesting the water would not be expected.
B. Health Outcome Data Evaluation
The North Carolina Department of Human Resources provided ATSDR with vital statistics information for Caldwell County and North Carolina (Tables 9 and 10). The data do not indicate any significant differences between the birth and death rates of Caldwell County and the State.
The adjusted cancer death rates for Caldwell County are similar to the state cancer death rates (Table 11). ATSDR's review of available data did not find any area within the county where incidence of cancer or noncancer adverse health effects is greater than would be expected. Data are not available for the population level needed to determine whether there is a higher than expected incidence of cancer or noncancer adverse health effects in the community near the CSI facility.
In September 1990, NIOSH conducted full evaluations of fourteen of fifteen workers invited to participate in the the study. The purpose of the evaluations was to develop criteria for health outcomes (case definition) for an epidemiologic study to determine whether reported neurologic disorders were associated with exposures to hazardous wastes at CSI. Fifteen workers were given two questionnaires, a general physical exam, examinations by two neurologists, and an interview with a psychiatrist. One of the workers refused the full neurologic exams and the psychiatric interview. The most commonly reported symptoms were non-specific in nature. The evaluations did not show objectively quantifiable findings that could be used as a case definition for evaluating other Caldwell workers (49).
In July 1991, ATSDR conducted a cross-sectional symptom and disease prevalence study of 713 residents living within 1.5 miles of the CSI site and 588 residents of a comparison area, Gamewell. A questionaire was administered to ascertain and compare the prevalence of respiratory, musculoskeletal, neurological, irritative and other symptoms and diseases among persons living in the two areas, based upon information about health complaints from their physicians. That study determined that the prevalence of irritant, respiratory, and neurological symptoms was statistically increased in the target area versus the comparison area. Neither physician-diagnosed diseases nor hospital admissions for those diseases differed in prevalence between the target and comparison areas. The prevalence of self-reported cancer or reproductive outcomes was not higher in the target area than in the comparison area (48).
In November 1991, 54 current and former Caldwell employees participated in screening examinations directed at finding movement disorders. The participation rate was low (17% of eligible participants). None of the 54 participants showed evidence of a movement disorder characterized by myoclonus and tremor. The most frequent neurologic finding was a mild postural tremor in eight participants (50).
C. Community Health Concerns Evaluation
The most common community health concerns reported to ATSDR were respiratory. As discussed in the Toxicological Evaluation section, the types of health problems reported at the CSI site are consistent with the types of problems that have been described in populations exposed to particulate and other emissions from incinerators. Thus, the health concerns reported by the community suggest that adverse health effects have occurred in community members as a result of their exposure to the site.
The respiratory complaints described by nearby residents are biologically plausible effects of exposures to particulate and other compounds produced by incinerators.
The most common complaints expressed by workers and their families were neurologic. Those complaints are plausible in individuals who have been exposed to solvents. In addition, several workers have described symptoms consistent with those seen in naval workers exposed to Otto Fuel. The complaints and health problems described by the workers and their families provide further indication that past exposures may have resulted in adverse health effects.
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