PUBLIC HEALTH ASSESSMENT
OKLAHOMA REFINING COMPANY
CYRIL, CADDO COUNTY, OKLAHOMA
ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
The tables in Appendix II list contaminants, which due to their concentrations, will be further evaluated for public health implications. The data referred to in the tables were collected primarily by OSDH for EPA; the information is contained in the 1991 RI report (1).
This section of the public health assessment discusses a number of chemicals in terms of their potential to affect public health. ATSDR selects and discusses the contaminants using the following information:
In the data tables in Appendix II, the fact that a contaminant is listed does not mean that it will cause adverse health effects in exposed people. Rather, the list indicates contaminants that will be evaluated further in this public health assessment. When a contaminant is selected as a contaminant of concern in one medium, its presence or absence in all media will be discussed.
Comparison values used in the public health assessment are contaminant concentrations in specific media used to select contaminants for further evaluation. Those values include Environmental Media Evaluation Guides (EMEGs), Cancer Risk Evaluation Guides (CREGs), and other relevant guidelines. EMEGs are derived from the Minimal Risk Levels (MRLs), ATSDR-derived estimates of daily human exposure to a chemical that are likely to be without an appreciable risk of deleterious effects (non-carcinogenic) over a specified duration of exposure. MRLs provide a measure of the toxicity of a chemical. CREGs are estimated contaminant concentrations that would be expected to cause one excess cancer in a million persons exposed over a lifetime. CREGs are calculated from EPA's cancer slope factors. EPA's Reference Dose (RfD) is an estimate of the daily exposure to a contaminant unlikely to cause adverse health effects. ATSDR's Reference Dose Media Evaluation Guide (RMEG) is calculated from EPA's reference dose.
ATSDR conducted a search of the EPA Toxic Chemical Release Inventory (TRI) -- an on-line database containing information (self reports from chemical manufacturers and other companies throughout the United States) about more than 320 different substances released from facilities into the environment -- for the site and surrounding area. No releases were reported under the facility name for the years 1987-1989, the first years available for searching. Although Oklahoma Refining Company was abandoned by these dates, a search by zip code for the same years also found no reported releases. Contaminants of health concern related to the site are discussed in the following paragraphs.
Samples taken during the RI confirmed the presence of hydrocarbons, heavy metals, and volatile and semi-volatile organic compounds in groundwater and soils at ORC. Contaminants listed for further evaluation are shown in Tables 1-9 (Appendix II) and are discussed by environmental media. The tables have been divided into inorganic compounds (heavy metals) and organic compounds (PAHs). Contaminants were not listed if they were found in a blank, suggesting possible laboratory contamination. The following compounds were eliminated for that reason: acetone, methylene chloride, and methyl ethyl ketone.
Waste Material
Waste material from refinery operations was placed in unlined pits and impoundments. Subsurface soil around the pits became contaminated as the waste material leached from the pits. No inorganic or organic compounds were identified in the land treatment area at levels of concern (adult); however, the pits and ponds contained higher concentrations.
Several heavy metals (arsenic, beryllium, and lead) are at levels of concern in soil (Table 1). Heavy metals were found in oil skimmer ponds, the North pond system, sludge traps, and lime soda, slop oil, asphalt, and old storage pits.
No non-carcinogenic organic compounds of concern (for an adult worker with chronic exposure to wastes or subsurface soils beneath the waste) were identified. However, there were carcinogenic contaminants of concern in the wastes and subsurface soils, primarily PAHs (Table 2). Those contaminants were detected in soils collected from on-site storage pits that were visibly stained with oily wastes. These storage pits were used for wastes generated during site operations, including asphalt, slop oil, and pitch pits, as well as for waste from the junction box of the process sewer.
Soils
Surface soils were sampled in the northwestern quadrant near the leaded gasoline storage tanks, cooling towers, pitch pits, separator, and asphalt flow and railroad-loading areas. The soils of other quadrants were characterized by waste source areas, as was discussed in the preceding section. Contaminants were evaluated for surface soils (upper 12 inches) only because ATSDR assumed that exposure to subsurface soils would be nil.
Because ORC has been an industrial site for more than 80 years, it is not likely to have been a daily play area for children. Table 3 indicates that arsenic was found in concentrations that exceed the ATSDR comparison value for an adult. Lead concentrations were also at levels meriting further public health evaluation.
Several PAHs [benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, and chrysene] were found in restricted areas, such as the railroad loading area and near a leaded gasoline tank (Table 4).
Sediment
Seeps and a drainage ditch on ORC were examined for sediment contamination. The drainage ditch is in the refinery process area near abandoned leaded gasoline storage tanks and cooling towers. According to state health personnel, arsenic and chromium were used in the cooling towers to keep bacteria levels at a minimum. Groundwater seeps occur along Gladys Creek and its tributaries. The acidic and caustic seeps are hydraulically downgradient from the acidic and caustic pits, respectively. No contaminants exceeded comparison values for ingestion by an adult (Table 5). Hydrocarbons were found in all samples. The elevation of the ORC site places it above the 100 year flood plain, so that no major redistribution of sediment via flooding occurs. Discussion about sediments in Gladys Creek and its tributaries is in the Off-site Contamination section.
Surface Water
Groundwater discharge from the Rush Springs Sandstone Aquifer provides the base flow for Gladys Creek. Because ORC is bounded on the southeast by a deeply incised creek, groundwater from the site seeps out along the banks above Gladys Creek (5). The contaminants in the seeps affect surface water; therefore, they are considered surface water contaminants for purposes of this public health assessment.
Most of the metals found in surface water on ORC were in seeps at the acid leachate area. Lead was the only metal found at multiple surface water locations (Table 6). Organic compounds were detected in surface water in slop oil pits, sludge traps, and phenol spill areas. The phenol spill areas are located in the southeastern part of the site: one area near the refinery process area and another near the oil and sludge traps (Figure 2). Very few PAHs were detected in surface water (Table 7). When detected, the PAHs were at extremely low concentrations. Benzene was found in a drainage ditch. All on-site surface water samples showed the presence of hydrocarbons.
Groundwater
Groundwater contaminants include metals, PAHs, volatile organic compounds such as benzene, toluene, ethylbenzene, and xylenes (BTEX compounds), and semi-volatile organic compounds. LNAPLs are floating on perched groundwater in the area of the refinery and on the groundwater table in the Rush Spring Sandstone Aquifer (Figure 3). Tables 6 and 7 show the concentrations of selected contaminants in surface water and groundwater. The maximum concentration in groundwater often represents a sample taken from the LNAPL plume or hydrocarbon layer. Lead, chromium, barium, and arsenic are widespread in on-site groundwater. Table 7 shows that not all of the PAHs of concern for soil and sediment have been detected in groundwater. However, other PAHs, such as acenaphthene and fluorene, are present.
Ambient Air
Two foul-smelling areas were noted by ATSDR personnel during the 1991 site visit: the separator and the old caustic storage pits. Ambient air near these areas was monitored during remedial investigation sample collection.
The separator area was marked with a warning sign because of hydrogen sulfide. However, ambient air was monitored for hydrogen sulfide during the remedial investigation and none was detected (6). Wastes from the process sewers entered the separator before discharge to the storage ponds. Volatile compounds -- ethylbenzene and xylenes -- were found in the waste. An air quality investigation was conducted during the 1991 remedial investigation. Analyses were conducted for arsenic, barium, chromium VI, total chromium, BTX (benzene, toluene, xylene), phenol, cresol (methylphenols), and pentachlorophenols. Because field or laboratory blanks contained benzene and total chromium, the presence of the contaminants could not be verified. Chromium VI was not detectable in either on-site or off-site samples. The only air contaminants found were traces of toluene and xylenes.
The sampling stations closest to the old caustic storage pits were approximately 500 feet to the west. Prevailing winds during the sampling were to the north. It is possible that organic compounds such as phenols were not detected because of the station locations.
Because of the hydrogeology of the ORC site, groundwater contamination is largely restricted to the site. Contaminants have migrated off site through the surface water and sediment in Gladys Creek and most likely through the air pathway.
Sediment
Oklahoma Water Resources Board (OWRB) sampled sediments from Gladys and Chetonia Creeks and the Little Washita River between May 1982 and January 1983 (7). The sampling found arsenic, barium, chromium, lead, and hydrocarbons in sediments at elevated levels. Arsenic and barium concentrations exceed the comparison values for ingestion by a pica child (Table 8). However, locations not influenced by stream flow from the ORC site (upstream of the site and on the Little Washita River and Chetonia Creek) also had elevated levels of most of those metals (5). Most organic compounds were not analyzed for in the 1982-1983 study.
The 1991 RI report also contained sediment data (Table 8). The 1991 RI report also showed elevated chromium and lead concentrations. No organic compounds exceeded comparison values in the 1991 study.
Surface Water
Groundwater from ORC discharges into Gladys Creek and an unnamed tributary to the Creek. In addition to the groundwater flow, ORC directly discharged effluent into the creek before 1984. Hence, the quality of water in the creek has varied over time. An emergency discharge of phenols, ammonia, and sulfides from ORC in November 1982 affected the creeks for at least 2 miles downstream, or into Little Washita River (5). The Little Washita River was designated as a source of public and private water supplies by the Oklahoma Water Quality Standards of 1982. A neighboring farmer had irrigation rights to use water from Gladys Creek (Brown's Pond) to grow alfalfa. He irrigated from 1971 through 1980 and fed the alfalfa to cattle, which he then marketed.
Three studies have investigated the surface water quality near the ORC site; the results are documented in a 1982-1983 inspection report, 1984 monitoring results, and the 1991 RI report. Some of the results are summarized in Table 9 and are discussed in the following paragraphs.
The 1982-1983 inspection study was a one-time sampling of surface water locations near the ORC site (on Gladys Creek) and on several tributaries unaffected by stream flow from the ORC site. Arsenic and barium were detected in the water downstream of the ORC site at levels above local background concentrations. Arsenic and barium in creek water exceed comparison values for use as drinking water (Table 9). However, the creek water is probably not used as drinking water but could be incidentally ingested during swimming. Arsenic and barium ingestion during swimming will be considered further in the Toxicological Evaluation subsection.
From May through November 1984, a surface water quality study was conducted at the Gladys Creek Drainage basin. Samples were taken upstream of ORC through downstream waters past Whitfield Pond (Figure 2, Appendix I). Surface water was analyzed monthly for oil and grease, chemical oxygen demand (a test used to determine degree of pollution), arsenic, and chromium. Arsenic was a major contributor to water quality degradation. As was documented in the inspection report, arsenic was found to be widespread in Gladys Creek and in sediment (not water) of tributaries unaffected by surface water from the ORC site. Two locations, one upstream and one downstream of Whitfield Pond, had mean arsenic concentrations above the EPA maximum contaminant level of 50 ppb for drinking water. However, both arsenic and chromium concentrations were below their respective selection values for incidental ingestion (Table 9).
The 1991 report indicated no contaminants, except for a trace of hydrocarbons, were found above the minimum detection limit (MDL) in off-site creek water. Thirteen samples were taken at the following locations: Brown's Pond on Gladys Creek, the northwestern and southern tributaries of Gladys Creek, and upstream and downstream of ORC on the main tributary.
Most concentrations of arsenic in streams and rivers of the United States are below 10 ppb, but may range up to 1000 ppb (8). The arsenic concentrations reported for Gladys Creek appear to be at levels exceeding local background but not above some naturally occurring concentrations found in the United States.
Groundwater
To date, contaminated groundwater has been primarily restricted to the ORC site because the creek acts as a barrier to shallow groundwater flow. Contaminated groundwater is unlikely to migrate beyond Gladys Creek and its tributaries. Off-site migration could occur if the hydrological gradients were reversed as the result of pumping wells in Cyril or injection wells on site. Residents living just north of the site use the municipal water for domestic purposes. Water from the deep aquifer is used for industrial water purposes. Since area groundwater is not used for drinking water and contaminated groundwater is unlikely to migrate beyond the creek, no off-site groundwater contaminants are reported in this public health assessment.
Ambient Air
Current analyses of off-site air show a trace of toluene and xylenes. No past record of ambient air quality was available for review.
Fish
The OSDH sampled fish in Whitfield pond for heavy metals in October 1990. No elevated levels of metals were found (9). Although chromium, copper, and zinc were detected, the concentrations did not exceed those found in uncontaminated food sources or FDA acceptable limits. No metal analyses were conducted for fish in Brown's pond.
C. Quality Assurance and Quality Control
Quality assurance and quality control procedures were used by EPA to ensure the accuracy of sample collection and analyses. The conclusions in this public health assessment were derived from the data packages supplied to ATSDR. The accuracy of those conclusions depends on the reliability and comprehensiveness of the data in the materials reviewed. The earlier studies (1982-1985) were not undertaken by EPA, and quality control procedures used are not known.
Specific physical hazards associated with the site include abandoned equipment (pipelines and storage tanks) and numerous water-filled impoundments. ATSDR observed on-site physical hazards during their November 13, 1991 site visit. The pump pits and buried acid pits are areas where acidic conditions pose a physical hazard, particularly for trespassers.
The low-lying area where the old caustic storage pits used to be contains stressed vegetation and standing water. During the 1991 site visit, foul smelling odors were apparent in this area. Access to the western border of the site is limited by a 6-foot, chain-link fence. There are warning signs on the fence. Although access remains available on the eastern and southern sides of the site (near Gladys Creek), these borders have a steeply walled canyon which is difficult to cross. Adult-size foot prints were observed by ATSDR during the site visit and residents reported that hunters trespass on the site. Since our 1991 site visit, another fence with warning signs has been erected between the active refinery and the inactive southern portion of the site. This additional fencing has further restricted trespassing to contaminated pits, ponds, and traps. Trespassing may have occurred before additional fence and signs were installed but is unlikely under current site conditions.
Nets had been placed over some of the ponds used as oil and sludge traps to prevent water fowl from entering them. Although no large game were seen, waterfowl were seen swimming in on-site ponds. Evidence suggested that turtles and other small animals had ventured near the acid and asphalt pits. Birds and other wildlife apparently also had become trapped in the open asphalt pits.
Several fall type hazards exist on site. An unfenced area near the separator is several feet deep and contains hazardous substances. No caution signs other than the hydrogen sulfide warning sign exist and someone could easily fall into the pit beside the separator. One could also easily fall into the unmarked process sewer sludge boxes which contain hazardous substances.
Where accessible to the public, asbestos surrounding pipes on the outside of buildings on the
eastern side of ORC has been encapsulated. The asbestos problem has been abated by the Cyril
Petrochemical Corporation (6).
To determine if nearby residents or workers at a site have been or are being exposed to contaminants, ATSDR evaluates the environmental and human components that lead to exposure. Many residents worked at the Oklahoma Refining Company refinery during its operation and could have been exposed to contaminants both on and off site. Explanations are given in each section for classifying pathways as completed or potential. In general, a completed exposure pathway 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. A pathway is potential if at least one of the five elements is missing. A distinction has been made in this public health assessment between historical and current conditions. Tables on pathway analyses are found in Appendix III.
OSDH and EPA have also evaluated human exposure pathways of concern and the actual and potential risks -- both cancer and noncancer -- to human health from contaminants at the ORC site (1).
A. Completed Exposure Pathways
Contaminants from the ORC site have migrated off-site via Gladys Creek and its tributaries. Human exposure by ingestion, dermal contact, and inhalation probably occurred in the past, but is less likely under current conditions. Remediation of the site and proper procedures during remediation should minimize future exposures.
This public health assessment addresses past and current contamination. Future scenarios have been addressed in the RI report (1) and are summarized in following paragraphs. Pathways of human exposure to site contaminants are discussed in the following paragraphs and are summarized in Appendix III.
Creek Sediment Pathway
Given the historical data on sediment contamination in Gladys Creek and resident reports of children using the creek, the sediment pathway is considered completed. Children and adults have open access to the creek; the waterfall area adjacent to ORC is particularly appealing to children. Adults and children who come in contact with contaminated sediments are likely to ingest or have ingested site-related contaminants.
Creek Water Pathway
Given the historical data on water contamination in Gladys Creek (7) and resident reports of children using the creek, the creek water pathway is considered completed. Children and adults have open access to the creek; the waterfall area adjacent to ORC is particularly appealing to children. Adults and children who swam in or used the creek are likely to have to have absorbed contaminants dermally or through incidental ingestion. Gladys Creek is the primary pathway by which contaminants left and are leaving the ORC site.
Ambient Air Pathway
Under nonoperating and preremedial conditions at the site, air monitoring data suggest that the ambient air pathway does not represent a significant exposure pathway. However, when the previous refinery was operating, it was probably one of the most significant human exposure pathways. Volatile compounds such as benzene, toluene, ethylbenzene, and xylene probably were present in ambient air in the storage tank and refinery areas. Those compounds and other semi-volatile compounds are likely to have been released to the air during refinery operations. Although exposure to contaminants in air by dermal absorption or inhalation is currently considered minimal, those exposure routes probably had a greater effect in the past, when ORC was operating. However, because there are few historical data, health effects cannot be evaluated. We consider the ambient air pathway to be completed in the past based on the proximity of the residences to the site, volatile nature of the compounds being processed, and reports of odors from residents. ATSDR does not have air data for the current refinery operations.
Contaminants in soil, waste, and groundwater may become airborne through volatilization or from the release of fugitive dusts. Once airborne, contaminants may migrate to off-site areas. Remedial activities that disturb soil also may increase concentrations of airborne contaminants. Appropriate measures and controls should be undertaken during remedial activities to insure protection of workers and public health.
Since the refinery is active and remedial activities will begin, ATSDR recommends establishing background air quality and determining prevailing wind directions near the site (establishing a wind rose).
B. Potential Exposure Pathways
Exposure pathways are potential if exposure to a contaminant could have occurred, could be occurring, or could occur in the future. Potential exposure pathways at the ORC site are discussed in the following paragraphs.
Waste Source Pathway: Soil and Surface Water
Because there has been no discharge of contaminants since refinery abandonment in 1984, current concentrations of chemicals in wastes were considered equivalent or less than past concentrations. The waste source pathway is considered potential because on-site workers may have been exposed in the past. The pits, ponds, impoundments, separator, and land-farming area are considered the exposure points. On-site workers in the past may have inhaled volatile compounds from the surface waters and from soil in the land-farming area. Lack of environmental awareness and consideration of the chemical hazards is apparent from past practices at the refinery; pits were not lined, waste was discharged directly into creeks, etc. Workers involved with transporting wastes to on-site disposal areas potentially ingested or dermally absorbed contaminants from waste or soil.
Local residents reported that trespassing was common; area residents were known to hunt on site. The waste source pathway is considered a potential exposure scenario for trespassers. Site access is not totally restricted; therefore, trespassing by unauthorized personnel and contact with contaminated soil are possible although unlikely. Trespassers on site may be exposed to soil contaminants via skin contact, incidental ingestion, and inhalation of dusts.
Soil contaminants may be transported to off-site areas by storm-water runoff and wind erosion; however, because of the site's topography and grassy vegetative cover, wind and water erosion should be minimal. Remedial activities can increase soil exposure and therefore result in increased human exposure. However, appropriate measures and controls can be undertaken to insure protection of workers and residents.
Soil Pathway
Soil is considered a potential exposure pathway for off-site residents because their yards have not been sampled. ATSDR recommends sampling of residential yards near the site. Soil is also considered a potential exposure pathway for remedial workers because exposures may occur if protective equipment is not worn and if proper health and safety procedures are not followed. Past or current exposures around the tanks north of the railroad are possible; however, the area is vegetated which should reduce exposures.
Sediment Pathway
Along the steep western bank of Gladys Creek, the Rush Springs Sandstone aquifer is exposed, resulting in numerous areas of groundwater discharge and leachate seeps. Active seeps of acid wastewater containing oil and grease have been documented by EPA Region VI personnel visiting the site. The seeps are a hydrologic connection between on-site groundwater and off-site surface water.
On-site sediment in the drainage ditch and seeps is not particularly accessible; exposure is unlikely but could occur. Past workers or site trespassers may have been exposed to contaminated sediment by ingestion or dermal contact.
Surface Water Pathway
Surface water is not a source of drinking water in the site vicinity; however, surface water is used for agriculture. Surface water is a major pathway by which contaminants at ORC have and are migrating off site. Surface water runoff from downtown Cyril drains east and onto the ORC site and, with runoff from the site, drains east into Gladys Creek and south into an unnamed tributary of Gladys Creek. Surface water runoff from the site may carry contaminated soil and surface impoundment wastes to off-site areas. Because of the site's flat topography, surface-associated soil erosion should be minimal for all but the extreme eastern part of the site.
Groundwater Pathway
The groundwater beneath ORC is contaminated with heavy metals, petroleum hydrocarbons, and PAHs. Current or future ingestion of contaminated groundwater is unlikely because local residents living north and west of ORC are served by the Cyril municipal water system. However, some residents may use private groundwater wells for gardens and other domestic purposes. Their wells are hydrologically upgradient of groundwater contamination and therefore, are unlikely to be contaminated. Several private wells to the south and east are used for drinking water; however, they have been tested by OSDH and were found to be uncontaminated. They are hydrologically separated from contaminated groundwater at the site. Additional groundwater monitoring data and results from laboratory analyses of samples obtained from local municipal wells did not reveal any site-associated contamination. Groundwater contaminants from on-site areas may migrate off site via surface flow in Gladys Creek. They are unlikely, however, to affect private wells downgradient of the site. If residents move on site in the future, they would most likely be served by municipal water systems. Former workers may have inhaled volatile compounds during industrial use of groundwater.
Human exposure to groundwater contaminants via ingestion, dermal absorption, or inhalation may result from use of contaminated groundwater for domestic, industrial, and agricultural purposes. Although contaminants at levels of public health concern were detected in samples obtained from on-site groundwater monitoring wells, groundwater contaminants have not been detected in off-site areas other than the creek.
Two major aquifers are in the site area: the Rush Springs Sandstone water table aquifer and the deeper Duncan Sandstone Aquifer. The Rush Springs aquifer has acceptable water quality and is a source of drinking water for local domestic and municipal wells. Depth to groundwater in the Rush Springs aquifer varies from 2 to 16 feet beneath the surface of the site. The Rush Springs Sandstone aquifer, which is approximately 200 to 250 feet thick, is exposed along portions of nearby Gladys Creek. Groundwater flow in the Rush Springs Sandstone aquifer in the site area is to the southeast. Shallow groundwater seeps and leachate discharge points are found along the banks of Gladys Creek and the deep ravine in which the creek is located. Water in some wells of the southeastern quadrant of the site is under artesian pressure. The water table and the Duncan Sandstone Aquifer are separated by 600 to 800 feet of interbedded shale, siltstone, and stone. The two aquifers are not naturally hydraulically interconnected. Depth to the Duncan Sandstone Aquifer in the Cyril area is between 850 to 1,010 feet below ground surface. The Duncan Sandstone Aquifer water contains large amounts of salt and sulfates, making it a less suitable source of drinking water, but a valuable source of industrial water (1). Groundwater flow direction in the Duncan Sandstone aquifer is unknown (6). Seven on-site industrial wells, installed in the 1920s, draw water from the Duncan Sandstone aquifer. Two of these wells have been plugged because hydrocarbons entered the casings (6). Although the casings had deteriorated due to corrosive water, no known contamination entered the Duncan Sandstone (6).
Four hydrogeologic units are contaminated at the ORC site: the upper Rush Springs Sandstone aquifer, the intermediate Rush Springs Sandstone aquifer, the canyon fill alluvium water zone, and the gypsum perched water zone. Groundwater within the canyon fill alluvium is fed primarily by groundwater from the Rush Springs Sandstone aquifer (1). The perched water zone in the gypsum is discontinuous and lies above the Rush Springs Sandstone Aquifer.
Food Chain Pathway
Groundwater, soil, and surface water contaminants may have bioaccumulated and may now be bioaccumulating in the food chain (e.g., crops and animals). Gladys Creek downstream of the ORC site was used to irrigate approximately 55 acres of alfalfa. The alfalfa was fed to cattle, which were then marketed. Historical data indicates some contamination of Gladys Creek in the area where the irrigation occurred. Arsenic is frequently found in plants; it could bioaccumulate in vegetation at ORC and in vegetation and fish downstream in the creek system. Fish in Gladys Creek, downstream of the site, were analyzed for inorganic contaminants including arsenic and no elevated levels were found (9).
Surface water from Gladys Creek is currently used to water cattle east of the site at a nearby pond
and south of the site at several locations. South of the site, Gladys Creek is in a steep-sided, 20-
to 25-foot ravine that is not easily accessed by cattle. Near the site, Gladys Creek does not have
sufficient flow to support sport fish species; however, downstream of the site, flow increases and may support such species. Residents reported that people fish in Gladys Creek.
The potential health effects of persons exposed to site-related contaminants at ORC are discussed in the following paragraphs. ATSDR has developed a minimal risk level (MRL) for many contaminants found at hazardous waste sites. The MRL is an estimate of daily human exposure to a contaminant below which non-cancer, adverse health effects are unlikely to occur. MRLs are developed for route of exposure, such as ingestion and inhalation, and for length of exposure, such as acute (14 days or less), intermediate (15 to 364 days), and chronic (365 days or more).
Because no ATSDR MRLs were available for the contaminants of concern at the ORC site, the EPA reference dose (RfD) was used as the health guideline. An EPA RfD is an estimate of the daily exposure to a contaminant that is unlikely to cause adverse health effects.
Ambient air contamination may have been a significant past exposure pathway for on-site workers and residents living near the site when the refinery was operating. However, because there are no historical ambient air data with which to evaluate past on-site and off-site exposure via inhalation, the ambient air pathway could not be evaluated.
Contaminants of concern at ORC include hydrogen sulfide, metals (e.g., arsenic, barium, beryllium, and lead) and organic compounds (e.g., benzene, benzo[a] anthracene, benzo[b]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, chrysene, dibenzo[ah]anthracene, and indeno[1,2,3 cd]pyrene.
Arsenic
On-site workers or trespassers may be exposed to arsenic from dermal contact with or incidental ingestion or inhalation of on-site waste sources or soils. No adverse health effects would be expected in the infrequent (three to four times a year) trespasser who ingested incidental amounts of on-site soil or waste sources. Even though health guidelines are not available with which to evaluate dermal exposure to arsenic in on-site waste or surface soil, arsenic is not believed to pose a significant health threat because of the expected limited dermal contact of trespassers with the soil and waste. Arsenic was not detected in ambient air monitoring conducted during the remedial investigation and suggests that currently it poses no threat to on-site trespassers.
Current exposures of on-site workers with no personal protective equipment to on-site soils and waste sources pose an unacceptable health risk. Exposure to arsenic via incidental ingestion of on-site soil or waste sources over 20 years would be expected to result in an increase in the rate of cancer. For every 10,000 persons exposed to the concentrations of arsenic found in the ORC waste or on-site soil, an additional 2-3 cancers would be expected after 70 years. Several epidemiologic studies have reported that ingestion of inorganic arsenic increases the risk of developing skin cancers; the most common types are squamous cell carcinomas, which develop from hyperkeratic warts or corns (8). Basal cell carcinomas may also develop. An increase in internal cancers, such as bladder and liver cancer, has been reported, but evidence is still inconclusive (8). In the occupational setting, dermal contact with arsenical compounds has been reported to result in contact dermatitis. On-site workers at the Oklahoma Refining Company probably inhaled arsenic. The health effects of inhaling arsenic from on-site soils and waste could not be evaluated because there was no historical air monitoring data. It is expected that the adverse health effects reported for the current on-site worker may be similar to those of workers exposed in the past for an equivalent length of time.
A child could be exposed to arsenic from incidental ingestion or by dermal contact with the sediment or surface water while swimming in Gladys Creek. Acute ingestion of arsenic in the sediment (a child consuming 5000 mg of sediment during one exposure) should not produce adverse health effects in a child. If a child swam in the creek for 60 days per year for 15 years, the expected incidental ingestion of sediment or surface water contaminated with arsenic exceeds the EPA oral RfD (Table A). Even though the exposure dose exceeds the Rfd, there are no health effects expected to occur in the average person. However, some people are sensitive to arsenic. Dermal contact with sediments or surface water is unlikely to produce adverse health effects.
| CONTAMINANT | EXPOSURE PATHWAY | HEALTH GUIDELINE FOR INGESTION (mg/kg/day) | ||
| Value | Source | Exceeded by
estimated
exposure dose | ||
| Arsenic | waste sources, on-site soils |
0.0003 | EPA oral RfD | Noa Yesb |
| Arsenic | on-site soils | 0.0003 | EPA oral RfD | Noa Yesb |
| Arsenic | creek sediment | 0.0003 | EPA oral RfD | Yes |
| Arsenic | creek water | 0.0003 | EPA oral RfD | Yes |
Barium
Limited information indicates that only 5% of the administered dose of barium is absorbed by the human gastrointestinal tract (10). A child swimming or wading (exposure duration = 60 days per year for 15 years) in Gladys Creek would not be expected to have adverse health effects from incidental ingestion of creek sediment or surface water because the amount of barium ingested from that exposure does not exceed the EPA oral RfD (Table B).
| CONTAMINANT | EXPOSURE PATHWAY |
HEALTH GUIDELINE FOR INGESTION (mg/kg/day) | ||
| Value | Source | Exceeded by estimated exposure dose | ||
| Barium | off-site creek sediment |
0.07 | EPA oral RfD | No |
| Barium | off-site surface water |
0.07 | EPA oral RfD | No |
Benzo(a)pyrene
Several of the PAHs, including benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, chrysene, dibenzo(ah)anthracene, indeno(c,d)pyrene, and benzo(a)pyrene have been shown to cause cancer in laboratory animals if they ingest, inhale, or have dermal contact with these chemicals. The carcinogenic potential of exposure to PAHs (including benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, chrysene, dibenzo[ah]anthracene, indeno[1,2,3-c,d]pyrene, and benzo[a]pyrene) in the surface soil and waste sources in on-site soil at ORC were evaluated using a method of toxicity equivalency factors (TEFs) for carcinogenic PAHs based on each compound's relative potency to benzo(a)pyrene (11). In the future, exposure of unprotected on-site workers via incidental ingestion to PAHs in waste sources in on-site soil may pose an unacceptable risk. For every 1000 persons exposed for 20 years to PAHs in waste sources, an additional 1 or 2 cancers would be expected after 70 years. Because of that theoretical increase in the rate of cancer, ATSDR considers the exposure unacceptable. Exposure of on-site workers to PAHs via incidental ingestion of surface soil not containing waste sources does not appear to increase the risk of cancer.
PAHs can enter the body through the lungs when air containing particulates of PAHs is inhaled. This route of exposure is significant. Although there were no air particulate data with which to estimate the extent of such exposure, it must be considered a potential risk for the on-site worker. Dermal contact with PAHs in an oily mixture, which maybe found at an oil refinery site, also is a significant source of exposure for the on-site worker (12).
Benzene
Past and future on-site workers may have been and could be exposed via ingestion, inhalation, or dermal contact to benzene in on-site waste sources. Depending on the extent and duration of exposure, benzene produces different health effects, including gastrointestinal upset, blood disorders, and damage to reproductive organs (13). Benzene is a known human carcinogen. Incidental ingestion of or dermal contact with benzene in waste sources, however, does not pose a health threat for the past or future on-site worker. No increase in cancer risk is expected from incidental ingestion of or dermal contact with waste sources (Table C). In the past, inhalation of benzene from waste sources may have been a significant route of exposure for the on-site worker; however, ATSDR has no air data with which to evaluate that pathway.
| CONTAMINANT | EXPOSURE PATHWAY |
HEALTH GUIDELINE FOR INGESTION (mg/kg/day)-1 | ||
| Value | Source | Exceeded by estimated exposure dose | ||
| Benzene | waste sources, on-site soil |
0.029 | EPA's oral slope factor |
No |
Beryllium
Exposure of on-site workers or trespassers to beryllium may have occurred or could occur by incidental ingestion and inhalation of or dermal contact with contaminated waste sources or on-site soils. Incidental ingestion of beryllium from waste sources or soil at ORC does not pose a health threat because the dose consumed by incidental ingestion does not exceed EPA's oral RfD (Table D). If it is ingested, only very small amounts of beryllium are transported from the stomach or the intestine into the bloodstream. In the past, on-site workers may have had dermal contact with waste sources or contaminated on-site soil. Studies of workers with dermal exposure to beryllium have noted that certain people are sensitive to the agent. Those people can develop a beryllium allergy that results in skin granulomas (i.e., rashes or nodules on the skin). ATSDR cannot determine if inhalation exposure to beryllium poses a health threat because air data with which to evaluate the pathway are not available.
Beryllium is a carcinogen. At the concentrations found in waste sources and in surface soil at ORC, however, there is no increased risk of cancer for the long-term, on-site worker.
| CONTAMINANT | EXPOSURE PATHWAY |
HEALTH GUIDELINE FOR INGESTION (mg/kg/day) | ||
| Value | Source | Exceeded by estimated exposure dose | ||
| Beryllium | waste sources, on-site soils |
0.005 | EPA oral RfD | Noa Nob |
| Beryllium | on-site soils | 0.005 | EPA oral RfD | Noa Nob |
Hydrogen Sulfide
There is a potential for on-site trespassers and on-site workers to be exposed to hydrogen sulfide gas from the open pits. Even though, the ambient air concentration of hydrogen sulfide in proximity of the pits is not known, there is a potential danger. An individual entering an atmosphere containing hydrogen sulfide may at first encounter a strong noticeable odor. However, after a very short period of time, the hydrogen sulfide gas is no longer detectable by smell which may lead to exposure to toxic concentrations of hydrogen sulfide. Exposure to hydrogen sulfide gas produces the same signs and symptoms of poisoning as exposure to cyanide (respiratory distress, heart irregularities, and finally respiratory arrest). The only notable exceptions between hydrogen sulfide and cyanide poisoning are due to the irritancy of hydrogen sulfide. Chronic exposure to hydrogen sulfide at low concentrations may produce conjunctivitis of the eye or occasionally edema of the lung (14).
Lead
Inhalation and incidental ingestion of low levels of lead from waste sources or on-site surface soil at ORC may have produced or could produce biologic effects in the long-term, on-site worker. Neither ATSDR nor EPA have established health guideline values for lead because no threshold has been demonstrated for the most sensitive biologic effects in humans (Table E). Even very low levels of lead exposure, resulting in blood lead concentrations as low as 10 g/dL, produce biologic effects in people. The effects of lead are the same whether it is inhaled or ingested. Industrial workers are primarily exposed to the metal by inhaling lead-contaminated dust. Dermal exposure to inorganic lead is very unlikely. Only 10-12% of the incidentally ingested dose of lead in adults is absorbed by the gut. The most likely adverse health effects in the occupationally exposed worker are increases in blood pressure and hematological changes. After chronic lead exposure, men may sustain kidney damage, and spermatogenesis may be impaired (15).
| CONTAMINANT | EXPOSURE PATHWAY |
HEALTH GUIDELINE FOR INGESTION (mg/kg/day) | ||
| Value | Source | Exceeded by estimated exposure dose | ||
| Lead | waste sources, on-site soil |
None | None | ? |
| Lead | on-site surface soil |
None | None | ? |
B. Health Outcome Data Evaluation
Health outcome data were not available for analysis. Disease registries are currently being developed by OSDH.
C. Community Health Concerns Evaluation
The following health concerns were expressed by members of the community near the Oklahoma Refining Company site:
ATSDR is unable to determine if the incidence of brain cancer is higher in Cyril than other areas because state cancer registries are only now being established. Persons who worked on site at the refinery in the past are expected to be most affected by exposure to site contaminants. A review of epidemiologic studies performed to document the causes of mortality in petroleum workers does not indicate that brain cancer is a leading cause of mortality in workers exposed to petroleum products (16,17).
The ambient air pathway may have been a significant exposure pathway for off-site residents during past operations at the facility. There is no way to document the extent of that exposure, however, because there are no ambient air data for past site operations. No other complaints were reported to the city clerk, county sanitarian, or state health department during past or current operations at the ORC site.
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