PUBLIC HEALTH ASSESSMENT
DOVER CHEMICAL CORPORATION
DOVER, TUSCARAWAS COUNTY, OHIO
Investigations to determine the extent of chemical contamination at the Dover Chemical site were begun in 1981 following the discovery of buried chemical wastes on site. The company took groundwater and soil samples in May, 1981. Additional soil, sediment, surface water, and groundwater samples were collected between 1983 and 1986. A third round of samples were completed as part of the Remedial Investigation of the site. These previous investigations prompted additional rounds of sampling of the facility work areas, ambient air, surface soils, canal sediments, wastewater treatment plant effluent, and area groundwater with an emphasis on determining the concentration of dioxins and chlorinated dibenzofurans.
This section is not a complete listing of all of the chemicals found at the site. Most of the data reported were collected after 1989. A complete listing can be found in the RI report (Weston, 1994). Chemicals presented in this section will be discussed in further detail in other sections of the public health assessment. Chemicals listed in these Data Tables are not necessarily a threat to human health and may be eliminated in other sections of the public health assessment. Dioxin concentrations are given as 2,3,7,8 TCDD toxic equivalents (TEF). For a description of what is meant by toxic equivalents please see Appendix D.
Comparison values are used as guides to aid in the determination of the chemicals of concern. A chemical is not automatically included as a chemical of concern if it exceeds the comparison value. A chemical is included if people are or were exposed to it or if there was a reasonable probability that they might be exposed to it. Comparison values for the chemicals that do not cause cancer are either ATSDR's Environmental Media Evaluation Guides (EMEGs) or are calculated by ODH. The calculated values used the U.S.EPA Standard Reference Doses (RfD), adult and/or child body weights, and ingestion rates. If exposure to a child is not likely to occur, as in the workplace, the comparison value will be given only for adults. Cancer Guides are used to assist in the evaluation of the cancer potential for a chemical. They are calculated using the U.S.EPA cancer slope factors, adult body weights and ingestion rates. The formulas used for these calculations are included in Appendix C. The comparison values for drinking water are either the U.S.EPA Maximum Contaminant Level (MCL), ATSDR EMEGs, or calculated by ODH, which ever is the lowest number.
In 1989, as part of the Remedial Investigation at the Dover site, 164 samples were collected from the upper six inches of soil at 11 on-site areas. In 1990, 50 samples were collected from the upper six inches of soil at eight on-site areas. In 1991, 42 additional samples were taken from the upper six inches of soil at six on-site areas (Table 2).
The highest levels of the pesticide BHC (hexachloroclohexane) were detected in on-site soils in the vicinity of Building 21, an area used for the storage of alpha-BHC in the 1960's. The highest levels of dioxin were detected in on-site soils in Area H, a low-lying area at the southwest corner of the facility previously used for the disposal of chlorobenzene distillation wastes (Figure 2, Appendix A). Background surface soil concentrations of dioxin in Dover, typically range from 0.000005-0.00003 milligrams per kilogram (mg/kg). Surface soil concentrations on site are much higher than these background levels.
CONTAMINANT LEVELS IN ON-SITE SURFACE SOILS
DOVER CHEMICAL, DOVER, OHIO
|COMPARISON VALUE (mg/kg)|
|2,3,7,8 TCDD dioxin||ND-1.74||13|
1=Cancer guide number calculated by ODH
2=Noncancer comparison value calculated by ODH
3=ATSDR Policy Number
Subsurface soil samples were taken at the Dover Chemical site in 1981, 1983-84, 1985-86, and 1989. Soil sampling conducted in 1981 consisted of the drilling of a number of five-foot deep soil borings on site (Weston, 1993). Two "hot spots" were found directly east of Building 2 and one northwest of Building 31 (Figure 2, Appendix A). Soils in these areas contained up to 2% by volume organic chemicals. These soil "hot-spots" were excavated and removed to a regulated landfill for disposal.
Levels of organic contaminants in the 1989 samples were an order of magnitude lower than those recorded for on-site subsurface soil taken in 1983-1986. The differences in concentrations may be attributed to different sample locations and depths, differences in the types of soils, and the degradation of some types of chemicals. The highest levels of organic contaminants in subsurface soils consistently occurred in Area H at the southwest corner of the site (Figure 2, Appendix A). Chlorinated organic compound concentrations are uniform with depth, extending down to the water table. Contaminants detected included carbon tetrachloride, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, and 1,2,4-trichlorobenzene (Tables B-1 and B-2). Levels of chemical contaminants were slightly higher at depths below 1.5 feet.
Several areas were sampled before and after the interim soil removal actions at the site. Prior to the removal actions, dioxin concentrations ranged from 0.0035 mg/kg to 0.045 mg/kg. Dioxin concentrations dropped to below 0.001 mg/kg after the interim removal actions.
Between 1983 and 1992, 22 monitoring wells were installed on site to monitor groundwater quality under the Dover Chemical facility. The locations of these monitoring wells are provided in Figure 3 (Appendix A). Monitoring wells are screened at various depths within the sand and gravel aquifer that underlies the Dover site. The A-wells are screened at the depths averaging 30 feet below ground surface. The B-wells are screened between 45-60 feet below ground surface. The C wells are screened between 90-100 feet below ground surface. Monitoring well MW26 D is screened just above bedrock, between 223-230 feet below ground surface. In addition, there are four operational on-site production wells currently being used by Dover Chemical. Since 1988, monitoring wells at the Dover Chemical site have been sampled on a quarterly basis by Dover Chemical.
The highest levels of carbon tetrachloride in on-site groundwater were reported from monitoring well MW2A (Table 3), near the northeast corner of the Dover facility (Figure 4, Appendix A). The highest levels of the various chlorinated benzenes and dioxins in on-site groundwater were in the area of monitoring well MW11A, at the north end of Area H (Figure 5, Appendix A). Contaminant levels were highest in shallow portions of the underlying sand and gravel aquifer, 30 feet below ground surface.
CONTAMINANT LEVELS IN ON-SITE GROUNDWATER (1991)
DOVER CHEMICAL, DOVER, OHIO
|CHEMICAL||CONCENTRATION RANGE (µg/L)||COMPARISON VALUE (µg/L)|
ND=Chemical not detected
*Detected in one sample
1 = Cancer Risk Guide calculated by ODH
2 = U.S.EPA Maximum Contaminant Level
Surface Water and Sediment
Surface water and sediment from the canal were analyzed for hexachlorobenzene (HCB), BHC, dioxins, and dibenzofurans (Table 4). The canal carried cooling water from the Dover plant to the lagoon.
Effluent from the wastewater treatment plant entering Sugar Creek was also sampled. Dioxins measured in 2,3,7,8 TCDD equivalents, were detected in an unfiltered effluent sample at 0.00011 µg/L. Hexachlorobenzene was detected at 9 µg/L (estimated concentration) and gamma-BHC was detected at 0.25 µg/L (estimated).
CONTAMINANT LEVELS IN ON-SITE CANAL SEDIMENTS (1989)
DOVER CHEMICAL, DOVER, OHIO
ND=Chemical not detected
J=Concentration was estimated
Chemicals were found in sediment from only one canal sample which was closest to the Dover plant. Slightly higher levels of the various chlorobenzenes were detected in samples from depths of 1-2 feet at the same sample location.
Dover Plant Surface Wipe Sampling
Indoor areas of the Dover Chemical plant were sampled in 1989 for dioxins and dibenzofurans. Nineteen surface wipe samples were taken from high-dust areas in the maintenance building, buildings 21 and 17. Samples were also taken from tables and handrails in the lunchroom, main office, guard shack, buildings 25 and 27, and additional work surfaces in the maintenance shop. Dioxin levels in TCDD equivalents, ranged from 0.01-32.9 nanograms per 100 square centimeters (ng/100cm2 ). The highest levels were recorded for the maintenance shop and from the top of an I-beam in Building 17 (Figure 2, Appendix A). Dioxins were not detected in some areas including desks throughout the plant. Very small amounts of dioxins (below the levels of the solvent blanks) were detected on the handrails in buildings 17 and 27, and the lunchroom table.
Ambient air in the vicinity of the Dover Chemical plant was sampled upwind, on-site, and downwind of the site in 1989 and 1992, before and after the interim remedial action. The samples were taken with electronic weather stations mounted on 9-foot high tripods.
In the 1989 sampling, the downwind site had dioxin concentrations (measured in TCDD equivalents) nearly twice as high as upwind values (0.566 picograms/cubic meter compared to 0.291 pg/m3 ). The highest concentration of PCDD/PCDF (2.349 pg/m3 ) was recorded at the on-site station. In the 1992 sampling, the downwind sampling station had dioxin concentrations almost twice that of upwind stations (0.110 pg/m3 vs. 0.081 pg/m3 ). On-site air levels of dioxin (0.133 pg/m3 ), dropped significantly since 1989. On-site activities (constuction, excessive truck traffic), weather, and other possible sources in the area can all play roles in the changes in ambient air concentrations of dioxin.
Indoor air samples were taken from five buildings on-site in 1989. These included the control room in Building 17, Building 7, the lunch room, the security trailer, and the maintenance shop. Dioxin and dibenzofuran levels were measured using a high-volume PVF sampler set at six-feet above the ground surface, in the breathing zone. Dioxin levels ranged from 1.65 pg/m3 in an office in Building 7 to a high of 7.6 pg/m3 in the maintenance shop. All of these measurments are below U.S.EPA's exposure limit of 10 pg/m3.
Personal Air Sampling
A personal air sample was collected at the breathing zone of a janitorial worker at the Dover Chemical plant using a personal sampling pump. The worker's daily activities were in designated "clean areas", including the lunchroom, restrooms, locker rooms, and the front office. Samples were analyzed for dioxins and dibenzofurans. A sampling in 1990 detected dioxin levels (in TEFs) of 37 pg/m3. This level is above the U.S. EPA exposure limit of 10 pg/m3. A sample taken in 1992 indicated dioxin levels at 190 pg/m3. The level was much lower (0.5 pg/m3) when corrected for the presence of dioxin isomers in the laboratory blank sample (Weston, 1993). Using the corrected value, the levels of dioxin dropped significantly after completion of the interim remedial measures. However, the initial measurements were taken when the employee worked in clean areas of the plant.
Surface soils from the upper 1/4 inch or the upper six inches of soil were collected from 41 off-site areas surrounding the Dover Chemical plant (Figure 2, Appendix A). Samples were taken as part of the 1989 and 1990 Remedial Investigation of the site. Dioxins were detected in off-site surface soils at 37 of 41 sampling sites. The highest concentration of dioxin (0.549 mg/kg), was found in Area U, just across the fence and west of Area H, east of I-77 (see Figure 2, Appendix A). Other areas with comparatively high levels of dioxins in surface soils included shoulders along Davis and 15th Streets, in front of the Dover Chemical facility. Concentrations ranged from 0.002 mg/kg to 0.035 mg/kg. Concentrations were highest along Davis Street next to the site and dropped to below 0.004 mg/kg along 15th Street. It was noted during the site visit that the resident living in the corner lot along Davis and 15th Streets had a vegetable garden. It is not known if soil samples were taken in the garden. Background levels of dioxin in residential areas ranged from 0.000005 to 0.00003 mg/kg. Dioxin levels in surface soil from residential areas sampled after the interim remedial actions removed contaminated soil, were all below 0.001 mg/kg. The comparison value for 2,3,7,8 TCDD in soil is 1 mg/kg. As one can see, soil near residential areas contained dioxin below the comparison value.
In August, 1991, as part of the Remedial Investigation of the Dover Chemical site, groundwater from 20 off-site monitoring wells was sampled for a broad variety of organic chemicals. These off-site monitoring wells are all south of the Dover plant (Figure 3, Appendix A). Contaminants detected in groundwater from these wells are listed in Table 5. All off-site monitoring wells are screened in the sand and gravel aquifer at depths of 45-60 feet below the ground surface. Since 1991, the five on-site monitoring wells between the site and the city of Dover municipal well field have been sampled on a weekly basis. These wells contain carbon tetrachloride and dichlorobenzene above levels of concern.
The city of Dover public water supply wells are sampled weekly. In 1992, sampling of these wells indicated the presence of chloroform from ND-95 µg/L. The on-site monitoring wells between the site and the wellfield contain high levels of dichlorobenzene and carbon tetrachloride (Figure 4, Appendix A).
These data indicate that an elongate plume of organic chemicals has contaminated groundwater in the sand and gravel aquifer over an area that extends from the Dover Chemical site 4,000 feet to the south along Davis Street and portions of Tuscarawas Avenue.
In addition to monitoring well data, water samples were taken from 12 off-site private commercial water supply wells (Figure 3, Appendix A). Contaminants detected in these water supply wells are listed in Table 6. Two of these wells are no longer used. One of the wells is located at a local business and is not used as a drinking water source. The other well, RW-8, is a business supply well that provides water to the washroom.
Maximum contaminant levels were exceeded for a number of chemicals in four of the private commercial wells. These four wells are either not in use or are not used as a drinking water source. The residential wells sampled did not contain any chemicals of concern.
CONTAMINANT LEVELS IN OFF-SITE MONITORING WELLS (1991)
|CHEMICAL||CONCENTRATION RANGE (µg/L)||COMPARISON VALUE (µg/L)|
ND=Chemical not detected
1 = U.S.EPA Maximum Contaminant Level
2 = Cancer Risk Guide calculated by ODH
BDL =Below the detection limits
CONTAMINANT LEVELS IN OFF-SITE PRIVATE COMMERCIAL WELLS (1991)
|CHEMICAL||CONCENTRATION RANGE (µg/L)||COMPARISON VALUE (µg/L)|
|2,3,7,8 TCDD Dioxin||ND-0.0001 ppt||0.03 ppt1|
ND=Chemical not detected
ppt=parts per trillion
1 = U.S.EPA Maximum Contaminant Level
2 = Cancer Risk Guide calculated by ODH
Off-site Surface Water and Sediment
Surface water and sediment samples were taken in Sugar Creek and in the lagoon, west of the site. The upstream sample location in Sugar Creek was 3,000 feet upstream from the Dover Chemical NPDES outlet to Sugar Creek. The two downstream sample stations were just downstream of the NPDES outlet and just above the junction of Sugar Creek with the Tuscawaras River. Contaminants tested for included dioxins, the pesticide BHC, and hexachlorobenzene (HCB) (Table 7). Dioxin and pesticide levels were higher in downstream samples compared to the upstream sample. Sugar Creek is not used as a water supply, therefore, no comparison values are given for the chemicals detected in the water and sediment.
CONTAMINANT LEVELS IN OFF-SITE SURFACE WATER/SEDIMENT
|STATION||DIOXIN (ppb)||BHC (ppb)||HCB (ppb)|
ND=Chemical not detected
ppb=parts per billion
No surface water samples were taken from the lagoon west of the Dover plant. Sediment from the lagoon was tested for pesticides and dioxins. Dioxin was detected (0.60 ppb TCDD equivalents) in one lagoon sediment sample.
Fish Tissue Samples
Fish tissue samples taken at three stations in Sugar Creek were analyzed for dioxin/ dibenzofurans, the pesticide BHC, and the organic chemical hexachlorobenzene (HCB). Two samples of fish from the lagoon west of the site were analyzed for dioxins (Table 8). Both fillets or edible portion and whole body samples of the walleyes were analyzed. The Sugar Creek samples consisted of whole body composites of up to 21 fish per sample. The fish were very small and varied in length and therefore not useful in determining if a fish consumption advisory is warranted.
CONTAMINANT LEVELS IN OFF-SITE FISH TISSUE SAMPLES
|STATION||DIOXIN (µg/kg)||BHC (µg/kg)||HCB (µg/kg)|
ND=Chemical not detected
ppb=parts per billion
Fish from the on-site lagoon had higher levels of dioxins compared to fish collected off-site from Sugar Creek. The Food and Drug Administration has established that fish with dioxin levels less than 0.025 µg/kg are safe for human consumption (ATSDR, 1990).
C. Quality Assurance and Quality Control
In preparing this public health assessment, the Ohio Department of Health and ATSDR rely on the information provided in the referenced documents and assume that adequate quality assurance and quality control measures were followed with regard to chain-of-custody, laboratory procedures, and data reporting. The validity of the analysis and conclusions drawn for this public health assessment are determined by the completeness and reliability of the referenced information.
D. Physical and Other Hazards
There were no physical hazards noted during the site visit other than those that may be associated with the plant. The plant facility is fenced and is not likely to present a hazard to nearby citizens.
The Pathways Analysis Section contains discussions of how chemicals move in the environment and how people can be exposed to the chemicals. For example, chemicals in a landfill can move through a landfill into the groundwater or seep out of a landfill at the surface (leachate). Chemicals in soil can be blown off site by the wind or can be carried away from the site in rain water runoff.
Contaminated dirt at the Dover Chemical site has been carried off site by blowing dirt and dust and by cars and trucks traveling in and out of the facility. Contaminated dust and dirt has also been blown away from the site onto the edges of the yards along 15th Street.
Chemicals in the soil can also migrate into the groundwater at the site. Rainwater washes some chemicals through the soil into the groundwater. Chemicals that do not mix with water, such as dichlorobenzene and dioxins, can move through the soil by mixing with other chemicals such as solvents. Contaminated groundwater moves off site with the natural flow of the aquifer or by pumping of the groundwater by cities (for water supplies), businesses, and private drinking water wells. If the groundwater is used for water supplies, people can then be exposed to the chemicals present in the water.
The Dover Chemical site is located on the floodplain of Sugar Creek which is underlain by 230 feet of sand and gravel. This deposit forms an unconfined groundwater aquifer that is a source of water for the Dover Chemical plant, the city of Dover municipal water system, and for a number of private wells located east and south of the site. Natural groundwater flow in the area is from the northwest to the southeast, down the existing stream valley. Pumping by industrial production wells and city of Dover water supply wells has disrupted natural groundwater flow in the vicinity of the site. The city well field is 1,000 feet northeast and upgradient from the site. Residential and commercial private wells are located immediately to the south (downgradient) and east of the site. The closest private water supply wells are 500 feet east and southeast of the site.
Groundwater contaminated with carbon tetrachloride and chloroform at the north end of the Dover Chemical Plant is being pulled towards the city of Dover wellfield. Carbon tetrachloride has been detected in two monitoring wells within 600 feet of one of the city's wells (Figure 4, Appendix A). Groundwater contaminated with primarily with chlorobenzene at the south end of the Dover Chemical Plant is moving south away from the site. This "chemical plume" has contaminated four nearby commercial (private) water supply wells. These wells are not used for drinking, cooking, or showering. This contaminant plume extends 4,000 feet south of the Dover site (Figure 5, Appendix A).
Contaminated dirt can also be washed away from the site into local rivers and streams. The lagoon, west of the site and Sugar Creek both contained site-related chemicals. Once in the water and sediment, the chemicals can accumulate in the fish.
There are two types of human exposure pathways, completed and potential. A completed exposure pathway means that there is a source of the chemical (the site), contaminated media at the site (such as groundwater or soil), there is a way people can be exposed (people use groundwater for a water supply), and people are using the contaminated groundwater. The exposure could have occurred in the past, could be occurring now, or could occur in the future.
At the Dover Chemical site, dust and dirt are completed exposure pathways (Table 9). Surface soils on the Dover site once contained dioxins and different isomers of the pesticide BHC (hexachlorocyclohexane) above levels of concern (Table 2). Dust contaminated with dioxins was present in the maintenance shop and in Building 17. The contaminated dust was brought into these areas on pieces of equipment or tracked in by workers. Other areas in the facility including the lunchroom tables, desks, and handrails contained no or very little contaminated dirt or dust.
Workers at the plant, primarily those working in the maintenance shop and in areas outside with elevated soil concentrations, could have been exposed to BHC and dioxins. People can be exposed to contaminated dirt by inhaling dust, eating the dirt, or coming in contact with the dirt. Pieces of dirt can be ingested or consumed by eating food or smoking cigarettes with dirt on the hands. The exposure would have occurred in the past because soil clean-up activities have taken place as part of the interim remedial actions. Several areas were sampled before and after the interim soil removal actions at the site. Prior to the removal actions, dioxin concentrations ranged from 0.004 mg/kg to 1.7 mg/kg. Dioxin concentrations dropped to below 0.001 mg/kg after the interim removal actions. Personal air measurements taken prior to the interim actions indicated that exposure levels slightly exceeded the U.S. EPA exposure limits. However, these measurements were taken at a time when the worker's activities were in "clean" areas. The level of exposure after working in areas with elevated concentrations of dioxin in the dust is therefore, unknown.
A potential exposure pathway means that we are uncertain about one of the pieces of the pathway discussed previously. For example, if there is a site (anywhere U.S.A.) where groundwater is contaminated and there are no people currently using the water, there is a potential exposure pathway.
People could potentially be exposed to site-related chemicals by eating fish from nearby waters and eating home grown produce, and by drinking contaminated groundwater. There is at lease one garden within 500 feet of the site. At one time, surface soil containing dioxin was present along 15th street. Contaminated soil along 15th street was removed and placed on site. This pathway is considered a potential exposure pathway because there are no monitoring data from the soil or any garden products from gardens close to the site.
The exposure to site-related chemicals is also possible if people catch and eat fish in Sugar Creek that are contaminated. Surface water and sediments in the on-site Canal, the lagoon, and Sugar Creek contained site related chemicals, primarily dioxin. Fish living in ponds or streams with contaminated sediment can accumulate the chemicals in their bodies. If people catch and eat these fish they can be exposed to the chemicals. Limited fish tissue data indicated that fish in Sugar Creek and the Lagoon contained dioxin. The data are not adequate to consider the consumption of fish a completed exposure pathway. The fish that were analyzed were too small, just a few inches in length, to determine contaminant levels in fish that would be eaten. Whole body samples and not the edible portion of the fish were analyzed.
Groundwater at the Dover Chemical site is a potential exposure pathway because there is no evidence that people are being exposed to chemicals at levels that would adversely affect their health (Table 8). No data indicates that people are using the contaminated groundwater as a drinking water supply. One well at a local business contained several VOCs. Water from this well is not used for drinking water.
When a water source is contaminated with chemicals above levels of concern exposure may occur by three different ways or routes of exposure. People can be exposed to chemicals by drinking the water, inhaling chemicals that volatilize from water during showering or bathing, and by the skin coming in contact with the chemicals. Groundwater on site and off site contained different chemicals above levels of concern (Tables 5 and 6, Environmental Contamination Section). People could be exposed if ongoing remediation (pump and treating groundwater) and monitoring of the well field fails to detect chemicals entering the water supply.
An exposure pathway can be eliminated as a pathway of concern if a chemical is in the groundwater or soil, but people are not in contact with the contaminated dirt or water. For example, groundwater at a site or near a site is contaminated, but everyone within a 10 mile radius of the site uses public water from a reservoir far away from the site. If people are not in contact with the contaminated water or dirt, they will not be exposed to the chemicals.
|Source||Media||Route of Exposure||Exposed Population||When Exposure Occurred|
|Completed Exposure Pathways|
|Groundwater||Skin Contact||People at Businesses with Contaminated Wells||Past|
|Potential Exposure Pathways|
|Residents of Dover||Future|
|Fish||Ingestion||Residents of Dover||Present,|
This section includes discussions of what is known about the chemicals to which human exposure is possible at the Dover Chemical site. There is often little information about the health effects caused by environmental exposures. Most human exposure studies use information from industrial exposures, where the doses are much higher. Industrial exposure data normally do not include precise information about the dose, the purity of the chemicals, their interactions with other substances, and the duration of the exposure or exposure to other chemicals. Animals do not necessarily show the same responses that humans do when exposed to toxic substances. However, in animal experiments using carefully controlled doses and time periods, researchers observe health effects that they believe are indicative of the responses shown by humans. Accordingly, when human information is unavailable, pertinent animal data will be incorporated into this section. Because comparison values for substances are calculated using safety factors and can be based on animal measurements, often there are no reported effects on people at comparison value concentrations. Unless otherwise mentioned, the information in this section will be taken from the ATSDR toxicological profiles.
Carbon tetrachloride was found in on-site wells at 3,800 µg/L. There are no data which indicates that people are currently being exposed to this chemical. If a person were to drink water containing carbon tetrachloride at levels found in on-site groundwater, the estimated dose may increase the risk of developing cancer if the exposure were to occur over the persons lifetime. This estimated dose does not incorporate exposures that may occur through skin contact and inhalation of vapors released from water during household use. Exposure could also result in dosages that would exceed levels of concern for adverse effects on the liver. Little is known about the long-term effects of low levels of carbon tetrachloride in people. During short-term exposures to high levels of carbon tetrachloride, people can experience liver and kidney effects. The lowest level of carbon tetrachloride that has been associated with harmful effects in animal studies is 1 mg/kg/day, which has produced liver changes.
Carbon tetrachloride is a manufactured compound that has a sweet odor. Most people can start to smell it in the air at 10 ppm. It has been used as a refrigerant, an aerosol propellant, and a cleaning fluid, and researchers believe that these uses may effect the ozone layer. Carbon tetrachloride can enter your body through the lungs if you breath air containing it and through the stomach if you swallow food or water containing it. When it is in the body some of it may stay in the fat and can enter the kidney, liver, brain and skeletal muscle. It may take weeks for the compound to be excreted, especially that in the body fat. Most is eliminated unchanged, but some of the chemical may change into such other chemicals as chloroform and hexachloroethane (ATSDR, 1992).
1-4, Dichlorobenzene (p-DCB)
P-DCB was found in on-site wells at 16,000 µg/L and in off-site wells at 1,600 µg/L. There are no data which indicates that people are currently being exposed to this chemical. If adults and children were to drink water at the levels found on site for their entire life, the estimated doses, 0.5 and 1 mg/kg/day, would exceed the U.S.EPA reference dose (0.1 mg/kg/day) and could cause harmful effects. The level of DCB presently in off-site groundwater (1,600 µg/L) should not pose a risk. The level of chlorobenzene found in several wells at nearby businesses would not pose a risk to people using this water. However, off site concentrations could increase over time. The reference dose is based on a lifetime of exposure, and there is no information to indicate that anyone has drank water with levels of DCB that would affect their health.
In animal studies, breathing or eating p-DCB can cause harmful effects in the kidney, liver, and blood. The lowest dose associated with harmful effects (18.8 mg/kg/day, in rats) has been shown to result in increases in liver weight.
1-4, Dichlorobenzene is a manufactured compound that is commonly used as a deodorizer and insect killer. It smells like mothballs. Most people can begin to smell it when it is present in the air at a concentration of 0.18 ppm and in water at a concentration of 11 µg/L. Most people's exposure to p-DCB is from breathing vapors in the home and workplace such as from room deodorant blocks and mothballs. The main way that p-DCB enters your body is through the lungs when you breath its vapors. When you breath this chemical for a few hours, about 20% of the amount that has entered your body will get into your bloodstream. It can also enter your body if you drink water or eat food that contains it. Most of the p-DCB that enters your body leaves through the urine in less than a week. Tiny amounts of the chemical remain in your fat and may stay there for a long time. In your body, p-DCB is broken down into other chemicals and it is unknown if these chemicals are toxic (ATSDR, 1993).
O-DCB levels in groundwater at the Dover site were as high as 15,000 µg/L and off-site monitoring wells had 1,400 µg/L of DCB .There are no data which indicates that people are currently being exposed to this chemical. If adults and children were to drink water at the level found on site, the estimated doses 0.4 and 0.9 mg/kg/day, would exceed the U.S.EPA reference dose of 0.09 mg/kg/day. This reference dose is based on effects on the kidney in rats and mice exposed to DCB. Reference doses are estimates of daily exposure of people that should be without adverse health effects. This means that a person could be exposed to 0.09 mg/kg/day of DCB and not suffer from any health effects. The level of DCB presently in off-site production wells (580 µg/L) or in off-site monitoring wells should not pose a risk, however, concentrations could increase or wells currently in use could become contaminated without remedial action.
Little data is available about the effects of o-DCB ingestion in people. O-DCB can be absorbed through the lungs when people breathe contaminated air and through the digestive tract when people consume contaminated water. Animal studies have shown that it is excreted relatively slowly; most of the compound is excreted in 6 days (NRC, 1983). No evidence was found that exposure to air containing o-DCB from 1-44 ppm resulted in health effects (IARC, 1974). In animals, concentrations as low as 5.0 mMol/kg (which might be comparable in concentration to the total absorbance of 0.7 mg/kg) were associated with changes in the bile duct-pancreatic fluid (Yang, et. al, 1979).
Chlorobenzene levels in groundwater monitoring wells at the Dover site were as high as 1,300 µg/L.There are no data which indicates that people are currently being exposed to this chemical. If adults and children were to drink water at these levels for their entire life, the estimated doses, 0.04 and 0.08 mg/kg/day respectively, would exceed the U.S. EPA reference dose of 0.02 mg/kg/day.
This reference dose is based on adverse effects in the liver of dogs. Reference doses are estimates of daily exposure of people that should be without adverse health effects. This means that a person could be exposed to 0.02 mg/kg/day of chlorobenzene and not suffer from any health effects. It dose not mean that just because a person was exposed at these levels they would suffer adverse effects on their liver. The reference dose is based on a lifetime of exposure, and there is no information to indicate that anyone has drank water with levels of chlorobenzene that would affect their health. The level of chlorobenzene found in several wells at nearby businesses would not pose a risk to people using this water.
Chlorobenzene is a colorless fluid with an almond-like odor. It can enter your body when you breathe in air that contains it and when you drink water or eat food containing it. Little information is available about the effects of low-level exposure in people. In animals, high concentrations can affect the brain, liver, and kidneys (ATSDR, 1992).
The concentration of L-PEC in the on-site wells was 1,400 µg/L. There are no data which indicates that people are currently being exposed to this chemical If adults and children were to drink water at these levels for their entire life, the estimated doses of 0.04 and 0.09 mg/kg/day, would slightly exceed the U.S.EPA reference dose of 0.01 mg/kg/day. This means that a person could be exposed to 0.01 mg/kg/day of L-PEC and not suffer from any health effects. The reference dose is based on effects on reproduction in rats. The reference dose is based on a lifetime of exposure, and there is no information to indicate that anyone has drank water with levels of L-PEC that would affect their health.
1,2,4-Trichlorobenzene can be absorbed through breathing contaminated air and through ingesting contaminated drinking water and food (McNamara, et al., 1981). Studies of its distribution in the body show that its prolonged effects are related to its storage and slow release from the body, especially from body fat (U.S.EPA, 1981).
PERC was detected in off-site groundwater up to 53 µg/L. There are no data which indicates that people are currently being exposed to this chemical. If adults and children were exposed to PERC at the levels found in off-site wells, the estimated doses, 0.002 and 0.003 mg/kg/day, should not exceed the lowest levels of concern.
Most people can smell PERC when it is present in the air at a level of 1 ppm or more. PERC can enter your body when you breath air or drink water, containing it. Most of it leaves your body rapidly when you breath it out. A small amount stays in your body tissues. Part of the PCE that is stored in fat may stay in your body for several days or weeks. Some of it is changed into other chemicals and these are removed from your body in urine. Some of the chemicals that are formed from PERC may be harmful (ATSDR, 1993).
The health effects of breathing air or drinking water having low levels of PCE that are not much above comparison values are unknown. When people are exposed to levels that are much higher than comparison levels, they may experience headache, dizziness, sleepiness, confusion, nausea, difficulty in speaking and walking, and possibly unconsciousness and death. Animals that have been chronically exposed to PCE levels that are much higher than levels found at the Dover site can show liver and kidney damage.
TCE was detected in off site groundwater up to 49 µg/L. There are no data which indicates that people are currently being exposed to this chemical. If adults and children were exposed to TCE at the levels found in off site wells, the estimated doses would be 0.0014 and 0.003 mg/kg/day, respectively. The estimated doses should not exceed the lowest levels of concern.
TCE in groundwater degrades slowly. It can be broken down into compounds that are more toxic, such as vinyl chloride. TCE readily enters your body when you breathe air or drink water containing it. About half the amount you breath in will get into your bloodstream and organs; you will exhale the rest. If you drink it, most of it will be absorbed into your blood. Once it is in your blood, you liver changes much of it into other chemicals. Most of these chemicals leave your body within a day. You will also quickly breathe out much of the TCE that is in your bloodstream. The principal target organs of TCE in both humans and animals are the bone marrow, brain, spinal cord, liver, and kidney (ATSDR, 1993).
TCE in drinking water in combination with other volatile organic compounds (VOCs) has been associated with congenital mouth and nervous system defects and very low birthweight (Bove et al., 1992), childhood leukemia, deaths around the time of birth, childhood disorders, and congenital abnormalities (Lagakos, 1986). TCE has also been associated with leukemia and recurrent infections (Byers et al., 1988), and heart disease (Goldberg, 1990). These studies, however, did not provide sufficient evidence that TCE causes these harmful health effects because the people were exposed to more than one chemical simultaneously. It is difficult to determine which chemical or combination of chemicals would be associated with the various adverse effects. Moreover, information on other risk factors for these adverse effects was not included in these studies (ATSDR, 1993).
The chlorinated dibenzo-p-dioxins are a class of substances that are referred to as dioxins. There are over 70 possible forms of this compound. The one with four chlorine atoms in a particular arrangement (2,3,7,8-Tetrachlorodibenzo-p-dioxin, or 2,3,7,8-TCDD) is believed to be the most harmful of these compounds. The U.S.EPA classifies the toxicities of the other forms (TCDD/TCDFs) by assigning each isomer a toxicity equivalency factor (TEF) with respect to the toxicity of the most toxic form (2,3,7,8-TCDD) (Appendix D). Dioxin does not occur naturally; it is an impurity in the manufacture of certain pesticides and of the incineration of certain wastes. Dioxin can enter a person's body through the ingestion of contaminated dirt, dust, fatty food, water, through breathing in contaminated dust, and through skin contact with contaminated soil.
The maximum concentration of dioxin in soil on site was 1.7 mg/kg toxic equivalents. If workers were exposed to dioxin at this level for as little as ten years they would have an increased risk of developing cancer. This would mean that a worker would have to ingest 100 mg of dirt every day for ten years. The Public Health Service recommends a safe level of dioxin intake is 5.7 x 10-8 or 0.000000057 µg/kg/day (Abadin, 1994). This is a risk-specific dose based upon a 1 x 10-6 risk of developing cancer. This means that one person would develop cancer if a million people were exposed to that dose for a lifetime.
Groundwater on site was also contaminated with dioxin. Concentrations ranged from not detected to 0.016 µg/L toxic equivalents of 2,3,7,8-TCDD. If a person were to ingest groundwater containing dioxin at levels found in on-site groundwater, the estimated dose would exceed levels of concern.
Doses of dioxin as low as 0.1 µg/kg/day have resulted in physiological responses (Roberts, 1991a). Many researchers believe that there is no evidence of a threshold, or safe level of dioxin exposure. Among the effects that may be associated with exposures to low levels of dioxin are birth defects, immune-system damage, and neurological abnormalities (Schmidt, 1992); the production of widespread disruption in the body's hormonal messenger system; a boosting of the potency of some hormones like epidermal growth factor which can lead to skin eruptions and perhaps to various cancers; changes in sex hormone levels; effects on insulin; the production of permanent effects in children exposed in the womb; changes in sexual development; reduction in sperm counts; possible functional deficits in the next generations; and a worsening of common degenerative diseases such as Alzheimer's and Parkinson's diseases. Recent studies of Air Force personnel following exposure to dioxin showed associations between serum dioxin and several lipid-related health indices, including diabetes, percent body fat, cholesterol, High Density Lipoproteins (HDL), and the cholesterol-HDL ratio (Roegner et al., 1991). Chloracne, a severe skin lesion, has been definitively identified in people as resulting from dioxin exposure. Investigation of the dose level is limited because it can only be identified in a few other animals. A dose of around 0.01 g/kg/day in a 9 month feeding study in monkeys produced lesions that were similar to those experienced by people (ATSDR, 1989).
2,3,7,8-TCDD is considered to be a carcinogen (cancer-causing agent) in people (Gibbons, 1994). The overall cancer rate of people exposed to dioxin and a variety of other chemicals after a chemical factory explosion near Seveso Italy was less than expected. However there were increases in the rate of several cancers (gallbladder cancer, multiple myeloma, liver cancer, soft-tissue sarcoma, and nasal cancer). An EPA panel reached the conclusion that chemical workers exposed to large amounts of dioxin appeared to have an increased risk of developing two types of lethal cancer (lung cancer and soft-tissue sarcoma). The effects of dioxin may include a form of cancer promotion that takes place in such a way as to cause a wide variety of cancers, rather than a single hallmark type. Two recent human studies have supported the idea that TCDD may be cancer-causing in humans at fairly high doses. One study (Fingerhut et al., 1991) showed that workers exposed to TCDD are more likely to die from cancer than the general population. (However records on the workers whose exposures which began at least 20 years ago, when plant dioxin levels were typically higher than today's, showed nine times the normal rate for one particular cancer - soft-tissue sarcoma). A similar study (Manz, 1991) of workers in Germany showed that TCDD-exposed workers experienced a higher rate of death from all cancers compared to the general population. (Workers with more than 20 years' exposure, showed a cancer death rate that was 87 percent above normal.) Workers in all these studies were also exposed to many other chemicals.
Interactions between several of these agents are possible. Because many of these chemicals produce effects on the liver, interactions may occur between the effects of these chemicals and of other agents that affect the liver. In addition, interactions can occur involving certain enzyme systems such as the P450 system. Changes in this enzyme may indicate changes in how the liver is working.
Hexachlorocyclohexane, also known as benzene hexachloride (BHC) is a manufactured chemical that exists in several chemical forms (isomers). One form, lindane, (or gamma-BCH) was widely used as an insecticide. Alpha and beta-BHC are the isomers of concern at the Dover site. In general, BHC isomers are stored in fat. Beta-BHC leaves the body very slowly. Some of the substances that the body breaks BHC down into are harmful (one causes cancer in animals) (ATSDR, 1992). The BHC at the Dover site is found in the soil. The exposure pathways include inhalation of the compound from dust particles and in the air and ingestion from soil contamination. Intake can occur through such activities as smoking or eating with dirty hands.
Alpha-BHC was found in the soil at levels as high as 4.6 mg/kg and beta-BHC was found at levels as high as 100 mg/kg. Working at the site for 25 years or longer and being exposed to the highest level of BHC found on site every day, would slightly increase one's risk of developing cancer. Exposure should not exceed the levels of concern for noncancer health effects.
Little precise information about the effects of BHC in humans is available. Occupational studies of workers in the pesticide industry, have shown that breathing BCH can be associated with blood disorders, dizziness, headaches, and changes in the levels of sex hormones. People who have swallowed large amounts have had seizures and even died. In animal studies, long-term ingestion of HCH in rodents has been reported to cause liver cancer. All isomers of BCH can produce liver and kidney disease. Animals that have been fed alpha-BHC have had convulsions and animals that have been fed beta-BCH have gone into comas and have been reported to have had injuries to their ovaries and testes.
The only health outcome data readily available for review are cancer mortality statistics for Tuscarawas County. These data are not relevant when evaluating the potential effects from one site located in one city in the county.
Community concern appears to be minimal. At a public availability session one citizen expressed a concern about planting flowers and shrubs in her yard. ODH staff have also contacted the local union at the plant to determine if workers had any health concerns. Reportedly, workers have not expressed any concerns about their health. Some comments and concerns were expressed in letters sent to Ohio Department of Health during the public comment period.
1) Was anything done to the former owner at the time of discovery of the two buried containers?
Response: In 1981, the company reported to the U.S.EPA the discovery of buried drums containing hazardous wastes at the site. Soil samples collected from the two on-site disposal pits revealed high levels of dichlorobenzene and chlorobenzene. Nine hundred and seventy-five tons of contaminated soil and drummed chemicals were removed from the pits and disposed of off site.
2) You should be able to locate larger fish.
Response: The reason we recommended that the fish need to be sampled again was that they were to small to determine risks to people who catch fish in Sugar Creek and the lagoon. We have state standard for the collection of fish tissue samples and will work with whomever collects these samples to ensure proper quality and size of the samples.
3) Are you able to test our garden?
Response: We have recognized the need for gardens near the site to be samples and have recommended that this be done. We at the health department do not have the resources or ability to analyse the samples for dioxins.
4) On the evening when Dover Chemical had the cloud of supposed chlorine vapor rise from the plant, I had to close all of my windows quickly because of the smell. I got a headache, and my stomach and chest bothered me the next day. My chest still doesn't feel the best, and I get sleepy every afternoon. My nose and throat have also felt dry.
Response: We will obtain any information about this upset from Dover Chemical. We have no information in our files concerning this "cloud". It is possible, that is chlorine vapor was released from the facility, it would cause nose, eye, and throat irritation. These symptoms should stop when the chemical disipates.
5) The lack of public concern is understandable. It is hard to comprehend such dangers.
Response: ODH staff recognizes the need to provide information about the site to the public in a simplier more straight forward fashion. We have developed a fact sheet that discusses the public health assessment and the site in a shorter, easier to understand format.