PUBLIC HEALTH ASSESSMENT
SOUTH 8TH STREET LANDFILL
(a/k/a WEST MEMPHIS LANDFILL)
WEST MEMPHIS, CRITTENDEN COUNTY, ARKANSAS
This section of the public health assessment describes environmental sampling conducted previously at the site and identifies contaminants of concern found in specific environmental media. The selected contaminants are evaluated in subsequent sections of the health assessment to determine whether exposure to them has public health significance.
ATSDR selects contaminants for further evaluation based upon the following factors:
It is emphasized that identification of a contaminant of concern in this section does not mean that exposure to it will cause adverse health effects. As mentioned above, the potential for adverse health effects resulting from exposure to contaminants of concern will be evaluated in subsequent sections of the health assessment.
Comparison values for ATSDR public health assessments are contaminant concentrations in
specific media that are used to select contaminants for further evaluation. The values provide
guidelines used to estimate a dose at which health effects might be observed. Comparison
values, along with acronyms and abbreviations, used in the Environmental Contamination and
Other Hazards
and the Public Health Implications sections of this public health assessment are
listed and described below.
| = Environmental Media Evaluation Guide | |
| = Reference Dose-based Media Evaluation Guide | |
| = Lifetime Health Advisory | |
| = Maximum Contaminant Level | |
| = Maximum Contaminant Level Goal | |
| = Minimum Risk Level | |
| = Reference Dose (mg/kg/day) | |
| = Not detected | |
| = milligrams per liter (mg/l water) milligrams per kilogram (mg/kg soil) |
|
| = micrograms per liter (µg/l water) micrograms per kilogram (µg/kg soil) |
|
| = kilogram | = milligram |
| = microgram | |
| = liter |
Environmental Media Evaluation Guides (EMEGs) are based on ATSDR minimal risk levels (MRLs) and factor in body weight and ingestion rates. Reference Dose-based Media Evaluation Guide (RMEGs) are based on EPA Reference Doses (RfDs) and factor in body weight and ingestion rates.
Lifetime Health Advisories (LTHAs) represent contaminant concentrations that the Environmental Protection Agency (EPA) deems protective of public health (taking into consideration the availability and economics of water treatment technology) over a lifetime (70 years) at an ingestion rate of two liters of water per day. The LTHA covers systemic (non-carcinogenic) health effects only.
Maximum Contaminant Levels (MCLs) represent contaminant concentrations that EPA deems protective of public health (considering the availability and economics of water treatment technology) over a lifetime (70 years) at an exposure rate of two liters per day (for an adult).
Maximum Contaminant Level Goals (MCLGs) are drinking water health goals set at levels at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Such levels consider the possible impact of synergistic effects, long-term and multi-stage exposures, and the existence of more susceptible groups in the population. When there is no safe threshold for a contaminant the MCLG should be set at zero.
EPA's Reference Dose (RfD) is an estimate of the daily exposure to a contaminant that is unlikely to cause adverse health effects. However, RfDs do not consider carcinogenic effects.
Minimum Risk Level (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 each route of exposure, such as ingestion and inhalation, and for the length of exposure.
As previously discussed, sampling data have been collected from various environmental media on and around the South 8th Street Landfill site on several occasions. These sampling investigations were discussed in the Background section earlier in this document.
The most recent site investigation -- the EPA Remedial Investigation (RI) -- was conducted in 1992. RI activities included the following: (1) digging of shallow trenches and sampling of subsurface soil from the trenches; (2) drilling and installation of monitoring wells; (3) collection of surface soil and surface sediment samples from on and off site areas; (4) groundwater sampling of the monitoring wells; (5) collection of sludge solids and liquids from the large, oily sludge pit; (6) collection of surface water and sediment samples from the on-site pond at the northeast corner of the site; (7) collection of standing water samples from on-site areas; and (8) collection of surface water samples from the Mississippi River upstream and downstream of the site. Most of the samples collected during the RI were analyzed for volatile organic compounds (VOCs), semi-volatile compound such as polycyclic aromatic hydrocarbons (PAHs) and phenols, PCBs, pesticides, and heavy metals. Selected samples were also analyzed for dioxins/furans (3,4).
Relevant contaminant data from the RI are evaluated under the "On-Site Contamination" and "Off-Site Contamination" subsections below. Available data from other site investigations are limited but are also evaluated where possible. For the purpose of this health assessment, "on-site includes 1) the three fenced areas (Areas 1, 2, and 3); 2) the area along the Mississippi River outside of the site fencing, and 3) the dirt-road portion of South 8th Street passing through the site. All other areas (e.g., the RV park) are considered "off-site". These designations are generally consistent with the those utilized in the RI.
Waste Materials
During the 1992 RI, samples of sludge solids and liquids from the large, oily sludge pit were collected and analyzed for VOCs, semivolatile organics (including PAHs and phenols), PCBs, pesticides, dioxins, and metals. The sludge sampling locations are shown in Figure 4.
As indicated in Table 1a, the sludge solids contained numerous VOCs, PAHs, phenols, PCBs, and metals. Some of the metals were present at levels similar to background soil concentrations in the site area; others, such as barium, cyanide, lead, mercury, and zinc, exceed background soil levels.
The liquid sample (sludge pit water) contained significantly fewer contaminants than the sludge solids samples. Contaminants detected in the liquid sample included VOCs, phenols, and metals (Table 1b.)
Table 1a. Contaminant Concentrations in On-site Sludge Pit Borings (Solids) Samples
| Contaminant | Concentration Range - ppm (mg/kg) |
Sample Date |
Reference | ||
| 1,2-Dichloroethane | 0.13 - 1.4 | 1992 | (6) | 8 | CREG |
| Benzene | 0.13 - 1 | 1992 | (6) | 20 | CREG |
| Chloroethane | 0.33 - 12 | 1992 | (6) | None | |
| Chloromethane | 0.83 - 5.1 | 1992 | (6) | None | |
| Methylene chloride | 0.74 - 0.99 | 1992 | (6) | 90 | CREG |
| Tetrachloroethylene (PCE) | 0.11 - 3.3 | 1992 | (6) | 10 | CREG |
| Trichloroethene (TCE) | 0.085 - 0.7 | 1992 | (6) | 60 | CREG |
| 2-Methylnaphthalene | 45.5 - 100 | 1992 | (6) | None | |
| Benzo(a)anthracene | 3.45 - 27 | 1992 | (6) | None | |
| Benzo(a)pyrene | 4.1 - 11 | 1992 | (6) | 0.1 | CREG |
| Benzo(b)fluoranthene | 9.8 - 16 | 1992 | (6) | None | |
| Benzo(g,h,i)perylene | 3.45 - 7.5 | 1992 | (6) | None | |
| Benzo(k)fluoranthene | 11 - 19 | 1992 | (6) | None | |
| Bis(2-ethylhexyl)phthalate | 12 - 58 | 1992 | (6) | 50 | CREG |
| Carbazole | 0.365 - 4.2 | 1992 | (6) | None | |
| Chrysene | 3.5 - 27 | 1992 | (6) | None | |
| Di-n-octylphthalate | 0.92 - 3.45 | 1992 | (6) | None | |
| Dibenzofuran | 2.15 - 2.5 | 1992 | (6) | None | |
| Naphthalene | 33 - 93 | 1992 | (6) | None | |
| Phenanthrene | 15 - 64 | 1992 | (6) | None | |
| 4-Methylphenol (p-Cresol) | 2.55 - 21.5 | 1992 | (6) | None | |
| 4-Nitrophenol | 1.485 - 14.95 | 1992 | (6) | None | |
| Pentachlorophenol (PCP) | 11.45 - 40 | 1992 | (6) | 6 | CREG |
| alpha-Chlordane | ND - 0.44 | 1992 | (6) | 0.5 (chlordane) | CREG |
| PCB-1242 | 2.5 - 9.9 | 1992 | (6) | 0.09 (PCBs) | CREG |
| PCB-1254 | ND - 14 | 1992 | (6) | 0.09 (PCBs) | CREG |
| PCB-1260 | ND - 5.1 | 1992 | (6) | 0.09 (PCBs) | CREG |
| Aluminum | 854 - 28300 | 1992 | (6) | None | |
| Arsenic | 3.6 - 11.2 | 1992 | (6) | 0.4 | CREG |
| Beryllium | 0.11 - 1.9 | 1992 | (6) | 0.2 | CREG |
| Cadmium | 0.8 - 12.4 | 1992 | (6) | 10 | EMEG |
| Cobalt | 0.77 - 9.3 | 1992 | (6) | None | |
| Lead | 6460 - 33600 | 1992 | (6) | None | |
| Mercury | 0.16 - 0.23 | 1992 | (6) | None | |
| Nickel | 13.2 - 44.7 | 1992 | (6) | None | |
| Thallium | ND - 2.0 | 1992 | (6) | 4 | RMEG |
| Vanadium | 2.6 - 31.3 | 1992 | (6) | None | |
Table 1b. Contaminant Concentrations in On-Site Sludge Pit Liquid/Water Samples
| Contaminant | Concentration Range - ppb (µg/l) |
Sample Date |
Reference | ||
| Benzene | 1 | 1992 | (6) | 1 | CREG |
| Chloroethane | 28 | 1992 | (6) | None | |
| Tetrachloroethylene (PCE) | 1 | 1992 | (6) | 0.7 | CREG |
| Trichloroethene (TCE) | 0.5 | 1992 | (6) | 3 | CREG |
| 4-Methylphenol (p-Cresol) | 620 | 1992 | (6) | None | |
| Aluminum | 1300000 J | 1992 | (6) | None | |
| Arsenic | 171 | 1992 | (6) | 0.02 | CREG |
| Beryllium | 71.6 | 1992 | (6) | 0.008 | CREG |
| Cadmium | 463 | 1992 | (6) | 2 | EMEG |
| Cobalt | 6500 | 1992 | (6) | None | |
| Lead | 3970 | 1992 | (6) | None | |
| Nickel | 3430 | 1992 | (6) | None | |
| Silver | 105 | 1992 | (6) | 50 | RMEG |
| Vanadium | 2190 | 1992 | (6) | 20 | LTHA |
| Zinc | 309000 | 1992 | (6) | 3000 | RMEG |
Surface Soil
Approximately 40 surface soil samples were collected at the site during the 1992 Remedial Investigation (RI) and analyzed for VOCs, semi-volatiles, phenols, PCBs, pesticides, and metals. The locations of these samples are shown in Figure 5.
Numerous PAHs and metals were detected in the site surface soil samples, along with some VOCs, pesticides [including 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT)], and PCBs. Table 2 shows the levels of soil contaminants that either exceeded ATSDR's comparison values or for which no applicable ATSDR comparison value exists.
Surface soil contamination was found within the fenced areas as well as outside the fenced areas
(e.g., along the dirt road). Except for some metals, the levels of nearly all contaminants detected
were greater than background surface soil levels in the site area.
Table 2. Contaminant Concentrations in On-Site Surface Soil Samples
| Contaminant | Concentration Range - ppm (mg/kg) |
Sample Date |
Reference | ||
| 1,1,1-Trichloroethane | ND - 0.003 | 1992 | (6) | None | |
| Methylene chloride | 0.001 - 0.006 | 1992 | (6) | 90 | CREG |
| 2-Methylnaphthalene | ND - 0.074 | 1992 | (6) | None | |
| Benzo(a)anthracene | 0.015 - 0.77 | 1992 | (6) | None | |
| Benzo(a)pyrene | 0.019 - 0.67 | 1992 | (6) | 0.1 | CREG |
| Benzo(b)fluoranthene | 0.045 - 1.5 | 1992 | (6) | None | |
| Benzo(g,h,i)perylene | 0.012 - 0.19 | 1992 | (6) | None | |
| Benzo(k)fluoranthene | 0.057 - 1.7 | 1992 | (6) | None | |
| Bis(2-ethylhexyl)phthalate | 0.042 - 0.064 | 1992 | (6) | 50 | CREG |
| Carbazole | 0.01 - 0.21 | 1992 | (6) | None | |
| Chrysene | 0.018 - 0.79 | 1992 | (6) | None | |
| Di-n-octylphthalate | 0.032 - 0.550 | 1992 | (6) | None | |
| Dibenzofuran | 0.042 - 0.067 | 1992 | (6) | None | |
| Naphthalene | 0.02 - 0.058 | 1992 | (6) | None | |
| Phenanthrene | 0.014 - 1.1 | 1992 | (6) | None | |
| alpha-Chlordane | ND - 0.022 | 1992 | (6) | 0.5 (chlordane) | CREG |
| PCB-1248 | ND - 0.690 | 1992 | (6) | 0.09 (PCBs) | CREG |
| 4,4'-DDD | 1.7 - 10 | 1992 | (6) | 3 | CREG |
| 4,4'-DDE | 0.61 - 6.2 | 1992 | (6) | 2 | CREG |
| 4,4'-DDT | 0.0057 - 11 | 1992 | (6) | 2 | CREG |
| Aluminum | 2060 - 18700 | 1992 | (6) | None | |
| Arsenic | 1.7 - 100 | 1992 | (6) | 0.4 | CREG |
| Beryllium | 0.19 - 1.7 | 1992 | (6) | 0.2 | CREG |
| Cadmium | 0.58 - 2.3 | 1992 | (6) | 10 | EMEG |
| Cobalt | 1.8 - 14.1 | 1992 | (6) | None | |
| Lead | 4.4 - 5810 | 1992 | (6) | None | |
| Mercury | ND - 0.49 | 1992 | (6) | None | |
| Nickel | 7.7 - 62.9 | 1992 | (6) | None | |
| Thallium | 0.16 - 0.45 | 1992 | (6) | None | |
| Vanadium | 6 - 42.3 | 1992 | (6) | None | |
Groundwater - Monitoring Wells
Two rounds of groundwater samples were collected during the RI from the 6 on-site monitoring wells that were installed during the RI field activities. Four of these wells (MW-2, MW-3S, MW-4, and MW-6S) are "shallow" wells, ranging in depth from 30 to 37 feet. The shallow wells were designed to monitor the water quality near the surface of the aquifer and to assess the ground water gradient and flow pattern in the vicinity of the site. The other two wells, MW-3D and MW-6D, with a depth of 150 feet and 147 feet, respectively, are considered "deep" wells. The deep wells were installed to assess the water quality deeper within the aquifer and to evaluate potential downward migration of contaminants. The monitoring well locations are shown in Figure 6 (6).
The first round of groundwater samples were collected in October 1992 upon completion of the monitoring well installation. During this sampling event, the predominant groundwater flow was from northwest to southeast (i.e., towards the river). A second, confirmatory round of samples were collected in April 1993 when the groundwater flow direction was from the southwest to the northeast, approximately perpendicular to the previous flow direction.
As shown in Table 3, a few organic compounds (volatile, semi-volatile, and phenols) were found
at low levels in the October 1992 and April 1993 groundwater samples. However, no volatile
compounds were found in the April 1993 samples. Several metals were detected in the first
round of samples, including arsenic, cobalt, and lead, at concentrations greater than the levels
measured in the background monitoring wells. In the second round of samples, metals were
measured at generally lower levels. However, since the groundwater flow direction was
significantly different during the first and second sampling rounds, comparison of the two data
sets may not be very meaningful.
Table 3. Contaminant Concentrations in On-Site Groundwater Monitoring Wells
| Contaminant | Concentration Range - ppb (µg/l) |
Sample Date |
Reference | ||
| 1,2-Dichloroethane | ND - 0.5 | 1992, 1993 | (4,6) | 0.4 | CREG |
| Methylene chloride | ND - 0.7 | 1992, 1993 | (4,6) | 5 | CREG |
| Trichloroethene (TCE) | ND - 4 | 1992, 1993 | (4,6) | 3 | CREG |
| Bis(2-ethylhexyl)phthalate | ND - 3 | 1992, 1993 | (4,6) | 3 | CREG |
| Di-n-octylphthalate | 0.1 - 4 | 1992, 1993 | (4,6) | None | |
| Pentachlorophenol | ND - 2 | 1992, 1993 | (4,6) | 0.3 | CREG |
| Aluminum | ND - 4590 | 1992, 1993 | (4,6) | None | |
| Arsenic | ND - 6.4 | 1992, 1993 | (4,6) | 0.02 | CREG |
| Barium | 89 - 1210 | 1992, 1993 | (4,6) | 700 | RMEG |
| Beryllium | ND - 2.8 | 1992, 1993 | (4,6) | 0.008 | CREG |
| Cadmium | ND - 5.3 | 1992, 1993 | (4,6) | 2 | EMEG |
| Cobalt | ND - 27.2 | 1992, 1993 | (4,6) | None | |
| Lead | ND - 242 | 1992, 1993 | (4,6) | None | |
| Mercury | ND - 0.21 | 1992, 1993 | (4,6) | None | |
| Nickel | ND - 60.7 | 1992, 1993 | (4,6) | None | |
| Vanadium | ND - 46.4 | 1992, 1993 | (4,6) | 20 | LTHA |
Surface Water
Four surface water samples were collected from the on-site pond, located at the northeast edge of the site (near the RV park), during the RI. These samples were analyzed for VOCs, semi-volatiles, PCBs, pesticides, and metals. The sampling locations are shown in Figure 5. Note: This pond is reported to have been used for wading, swimming, and fishing in the past.
Metals, including aluminum, arsenic, cadmium, cobalt, and lead, were the only contaminants of
concern found in the pond surface water samples (Table 4).
Table 4. Contaminant Concentrations in On-Site Pond Surface Water Samples
| Contaminant | Concentration Range - ppb (µg/l) |
Sample Date |
Reference | ||
| Aluminum | 356 - 664 | 1992 | (6) | None | |
| Arsenic | 3.4 - 4.3 | 1992 | (6) | 0.02 | CREG |
| Cadmium | 1.8 - 5.1 | 1992 | (6) | 2 | EMEG |
| Cobalt | 2.9 - 3.1 | 1992 | (6) | None | |
| Lead | ND - 3.4 | 1992 | (6) | None | |
Sediment
During the RI, five samples of sediment from the on-site pond were collected and analyzed for VOCs, semi-volatiles, PCBs, pesticides, and metals. The sediment sampling locations are shown in Figure 5.
As presented in Table 5, several PAHs (such as benzo(a)anthracene, benzo(a)pyrene,
benzo(b)fluoranthene, and pyrene) and metals (including arsenic, cadmium, cyanide, lead, and
zinc) were found in the sediments. VOCs (chlorobenzene and chloromethane) and DDT were
also detected; however, the levels of chlorobenzene and DDT did not exceed ATSDR's
comparison values.
Table 5. Contaminant Concentrations in On-Site Pond Sediment Samples
| Contaminant | Concentration Range - ppm (mg/kg) |
Sample Date |
Reference | ||
| Chloromethane | ND - 0.016 | 1992 | (6) | None | |
| Benzo(a)anthracene | ND - 0.085 | 1992 | (6) | None | |
| Benzo(a)pyrene | ND - 0.081 | 1992 | (6) | 0.1 | CREG |
| Benzo(b)fluoranthene | 0.11 - 0.15 | 1992 | (6) | None | |
| Bis(2-ethylhexyl)phthalate | ND - 0.057 | 1992 | (6) | 50 | CREG |
| Chrysene | ND - 0.092 | 1992 | (6) | None | |
| Phenanthrene | ND - 0.15 | 1992 | (6) | None | |
| Aluminum | 6380 - 17700 | 1992 | (6) | None | |
| Arsenic | 1.8 - 5.5 | 1992 | (6) | 0.4 | CREG |
| Beryllium | 0.25 - 0.59 | 1992 | (6) | 0.2 | CREG |
| Cadmium | 0.76 - 1.6 | 1992 | (6) | 10 | EMEG |
| Cobalt | 6 - 10.2 | 1992 | (6) | None | |
| Lead | 8.7 - 24.9 | 1992 | (6) | None | |
| Nickel | 14.4 - 65.5 | 1992 | (6) | None | |
| Vanadium | 18 - 42.8 | 1992 | (6) | None | |
Fish
In August and September 1992, an ecological characterization of the site was conducted by an EPA contractor. This characterization included the collection of three fish species from the on-site pond. Bluegill (Lepomis macrochirus) were collected for whole-body and fillet analysis, while largemouth bass (Micropterus salmoides) and channel catfish (Ictalurus punctatus) were collected for whole-body analysis only. These fish samples were analyzed for VOCs, semivolatiles, pesticides, and PCBs.
As shown in Table 6, several contaminants, including semivolatiles (pyrene and 2-methylphenol), pesticides (DDD, DDE, and DDT), PCB-1254, and metals (barium, mercury,
and zinc) were found in the fish tissue samples.
Table 6. Contaminant Concentrations in Fish from On-site Pond
| Contaminant | Concentration Range - ppm (µg/g) |
Sample Date | Reference |
| Pyrene | ND - 0.049c | 8/92, 9/92 | (2) |
| 2-Methylphenol (o-Cresol) | ND - 0.038a | 8/92, 9/92 | (2) |
| PCB-1254 | ND - 0.085d | 8/92, 9/92 | (2) |
| 4,4'-DDD | ND - 0.001a | 8/92, 9/92 | (2) |
| 4,4'-DDE | 0.001 - 0.017d | 8/92, 9/92 | (2) |
| 4,4'-DDT | ND - 0.009a | 8/92, 9/92 | (2) |
| Barium | 3.86b - 4.85a | 8/92, 9/92 | (2) |
| Mercury | ND - 0.725b | 8/92, 9/92 | (2) |
| Zinc | 9.74d - 26.6a | 8/92, 9/92 | (2) |
| a bluegill; b bluegill filet; c largemouth bass; d channel catfish | |||
Ambient Air
Ambient air samples were collected at the site in October 1988. Upwind and downwind air samples were reportedly taken at seven stations (1); however, the exact location of these sampling stations cannot be determined from currently available information.
As shown in Table 7a, benzene, ethylbenzene, toluene, and xylenes were detected in the downwind samples. (Note: Only benzene was present in excess of ATSDR comparison values.) The concentrations measured were more than three times the background (upwind) levels. It has been reported that other contaminants, such as PAHs and metals, were also detected in the October 1988 air samples. No sampling data for these contaminants, however, was found to confirm their presence.
During the 1992 RI, air samples were collected for VOCs using emission isolation flux chambers. Several samples, including 2 blanks, were collected from undisturbed locations prior to the excavation of exploratory trenches and from the disturbed areas during the trenching operations. The sampling locations are shown in Figure 7.
As shown in Table 7b, the following VOCs were found in the air samples at levels exceeding
ATSDR comparison values: benzene, 1,1-dichloroethene, methylene chloride, and
tetrachloroethene. Toluene and 1,1,1-trichloroethane were also detected but not at levels in
excess of ATSDR comparison values.
Table 7a. Contaminant Concentrations in On-Site Ambient Air Samples
| Contaminant | Concentration Range - ng/l |
Sample Date |
Reference | ||
| Benzene | 5.79 - 10.2 | 10/88 | (1) | 0.1 | CREG |
| Ethylbenzene | 7.37 - 12.29 | 10/88 | (1) | 1,000 | RMEG |
| Toluene | 34.42 - 93.45 | 10/88 | (1) | 1,150 | EMEG (acute) |
| Xylenes (total) | 89.47 - 147.54 | 10/88 | (1) | 220 | EMEG (acute) |
Table 7b. Contaminant Concentrations in On-Site Air Emission Samples
| Contaminant | Concentration Range - ng/l |
Sample Date |
Reference | ||
| Benzene | ND - 1.9 | 8/92-9/92 | (4) | 0.1 | CREG |
| 1,1-Dichloroethene | 2.2 - 3.0 | 8/92-9/92 | (4) | 0.02 | CREG |
| Methylene Chloride | ND - 14.5 | 8/92-9/92 | (4) | 2 | CREG |
| Tetrachloroethene (PCE) | ND - 7.6 | 8/92-9/92 | (4) | 2 | CREG |
| Toluene | ND - 61 | 8/92-9/92 | (4) | 1,150 | EMEG (acute) |
| 1,1,1-Trichloroethane | ND - 2.6 | 8/92-9/92 | (4) | 3,900 | EMEG (acute) |
Surface Soil
Off-site surface soil samples were collected at five locations during the RI and analyzed for VOCs, semi-volatiles, phenols, PCBs, pesticides, and metals. The locations of these samples are indicated in Figure 5. Two of these sampling locations were upgradient of the site (north of the RV park), one was downgradient of the site near the old farm field, one was across the levee near the RI command post, and the last was just outside the fence along the western edge of Area 3.
As shown in Table 8, VOCs, PAHs, pesticides, and metals were detected in the off-site surface
soil samples. In general, the contaminant levels were significantly lower than levels in on-site
surface soils, and in many cases did not exceed ATSDR's comparison values.
Table 8. Contaminant Concentrations in Off-Site Surface Soil Samples
| Contaminant | Concentration Range - ppm (mg/kg) |
Sample Date |
Reference | ||
| 1,1,1-Trichloroethane | 0.003 - 0.004 | 1992 | (6) | None | |
| Methylene chloride | 0.0009 - 0.007 | 1992 | (6) | 90 | CREG |
| Benzo(a)anthracene | 0.010 - 0.017 | 1992 | (6) | None | |
| Benzo(a)pyrene | ND - 0.019 | 1992 | (6) | 0.1 | CREG |
| Benzo(b)fluoranthene | 0.019 - 0.052 | 1992 | (6) | None | |
| Benzo(k)fluoranthene | ND - 0.018 | 1992 | (6) | None | |
| Bis(2-ethylhexyl)phthalate | 0.12 - 1.2 | 1992 | (6) | 50 | CREG |
| Chrysene | 0.010 - 0.017 | 1992 | (6) | None | |
| Di-n-octylphthalate | 0.031 - 0.260 | 1992 | (6) | None | |
| 4,4'-DDE | ND - 0.0038 | 1992 | (6) | 2 | CREG |
| 4,4'-DDT | 0.0037 - 0.0054 | 1992 | (6) | 2 | CREG |
| Aluminum | 5170 - 14300 | 1992 | (6) | None | |
| Arsenic | 3.2 - 8 | 1992 | (6) | 0.4 | CREG |
| Beryllium | 0.19 - 1.2 | 1992 | (6) | 0.2 | CREG |
| Cadmium | 0.58 - 2.1 | 1992 | (6) | 10 | EMEG |
| Cobalt | 5.1 - 11 | 1992 | (6) | None | |
| Lead | 26.4 - 68.8 | 1992 | (6) | None | |
| Nickel | 11.7 - 27 | 1992 | (6) | None | |
| Vanadium | 14.4 - 32.8 | 1992 | (6) | None | |
Groundwater - Monitoring Wells
Off-site groundwater samples were collected in October 1992 and April 1993 from Monitoring Wells 1S, 1D, and 5, which were installed during the RI field activities. MW-1S and MW-1D, which are 37 feet and 125 feet deep, respectively, are located northeast of the site, near the RV park. During low-to-normal river water levels, which were present during the October 1992 sampling activities, these two wells are considered to be upgradient of the site and, therefore, are referred to as "background" wells. However, during high river water levels, such as those that occurred during the April 1993 sampling events, these wells may actually be cross-gradient or down-gradient of the site. MW-5, with a depth of 40 feet, is located at the City of West Memphis police firing range, just west of landfill Area 1 (see Figure 6).
Groundwater samples from MW-1S, 1D, and 5 were analyzed for VOCs, semivolatiles, pesticides, PCBs, and metals (Table 9). The only organic contaminants detected in these wells were bis(2-ethylhexyl)phthalate, di-n-butylphthalate, and di-n-octylphthalate, which were found during both sampling rounds. Metals were generally found at levels similar to or less than the levels measured in on-site monitoring wells. In addition, the levels of metals in the April 1993 samples were generally lower than the levels in the October 1992 samples. An exception to this trend was mercury which was detected (5.8 ug/L) in the second round of samples but not in the first round. Note: Since the groundwater flow direction was significantly different during the first and second sampling rounds, comparison of the two data sets may not be very meaningful.
No off-site groundwater data for private wells (such as the RV park irrigation well) or public
wells in the general site area were located during the development of this public health assessment.
Table 9. Contaminant Concentrations in Off-Site Groundwater Monitoring Wells
| Contaminant | Concentration Range - ppb (µg/l) |
Sample Date |
Reference | Value | |
| Source | |||||
| Bis(2-ethylhexyl)phthalate | ND - 2 | 1992, 1993 | (4,6) | 3 | CREG |
| Di-n-octylphthalate | ND - 49 | 1992, 1993 | (4,6) | None | |
| Aluminum | 22.8 - 3620 | 1992, 1993 | (4,6) | None | |
| Arsenic | ND - 8.6 | 1992, 1993 | (4,6) | 0.02 | CREG |
| Barium | 125 - 782 | 1992, 1993 | (4,6) | 700 | RMEG |
| Beryllium | 0.87 - 2.4 | 1992, 1993 | (4,6) | 0.008 | CREG |
| Cadmium | ND - 3.4 | 1992, 1993 | (4,6) | 2 | EMEG |
| Cobalt | ND - 23.8 | 1992, 1993 | (4,6) | None | |
| Lead | ND- 64 | 1992, 1993 | (4,6) | None | |
| Nickel | ND - 63.8 | 1992, 1993 | (4,6) | None | |
| Vanadium | ND - 34.5 | 1992, 1993 | (4,6) | 20 | LTHA |
Surface Water/Sediment
The only major waterbody in the site area is the Mississippi River which borders the site on the southeast. Two surface water samples, one upstream of the site and one downstream, were collected from the river in April 1993. No pesticides, PCBs, or other organic compounds were detected in the surface water samples. Metal levels found downstream of the site were generally similar to the levels upstream of the site. These limited data suggest that contaminants from the site are not significantly impacting the Mississippi River. Moreover, site contamination is not expected to significantly affect the river since 1) stormwater runoff generally remains on-site and does not enter the river, and, therefore, contaminants in surface soils and sediments do not enter the river except when severe flooding of the site occurs; 2) contaminants in site groundwater are present only at low levels and have not been shown to be migrating into the river; and 3) the extremely large river flow would greatly dilute any contaminants entering the river from site drainage, flooding, and/or groundwater, especially during flood events when the river flow is much greater than normal.
No sediment data for the Mississippi River near the site were located during the development of this health assessment. However, for the reasons given above, river sediments are unlikely to be significantly impacted by contaminants from the site.
Ambient Air
As previously discussed, ambient air samples were collected at the site in October 1988. However, it is not known whether any of these samples were taken off the site, and, if so, to what extent they may have been affected by contaminants from the site. In addition, no off-site air samples were collected during the 1992 RI. No other information regarding off-site levels of air-borne contaminants has been found.
The Toxic Chemical Release Inventory (TRI) is a series of files for the reporting years of 1987, 1988, 1989, and 1990 which contain information on estimated annual releases of toxic chemicals to the environment (air, water, land, or underground injection) by certain industries and is based on data collected by the EPA.
To identify facilities that could contribute to the air, surface water, and soil contamination near the South 8th Street Landfill, ATSDR searched the 1987, 1988, 1989, and 1990 TRI. This search revealed that various toxic chemicals had been released to surface water and air by industries in the West Memphis area. These releases included wastewater discharges to the Mississippi River. However, it cannot be determined from the TRI information whether these releases have contributed to contamination at the site or whether persons in the site area have been exposed to contaminants from the releases. Therefore, the results from the TRI search are not considered further in this public health assessment.
D. Quality Assurance and Quality Control
The June 1993 RI report indicates that the RI data collection, handling, and analysis activities were conducted in accordance with the quality assurance/ quality control (QA/QC) requirements of the RI/FS Work Plan (WP), as specified in the Quality Assurance Project Plan (QAPP). Furthermore, data useability was determined to be acceptable based on an evaluation of data useability criteria and data quality indicators.
Validation of the RI/FS data was conducted by an EPA contract lab in accordance with the RI/FS WP, QAPP, and EPA guidelines. Validated data packages included the documentation review of QA/QC samples such as field duplicates, blanks, rinsate, and matrix spike/matrix spike duplicates. The data validation assessment demonstrated that the analytical results for RI/FS samples were largely useable with a limited number of individual data values qualified as "unusable". The validation also indicated that the RI/FS data meet the Data Quality Objectives (DQOs) specified in the QAPP. In the RI/FS data summaries, qualifiers were assigned due to items such as interference from high concentration samples, outlying calibration data, or low surrogate recoveries. However, the overall impact on the data quality is not considered to be significant.
Physical hazards present at the site include the large oily waste pit, which contains tar-like
substances, the on-site pond on the northeast edge of the site, and the adjacent Mississippi River.
These are considered physical hazards because of the potential for persons, especially small
children, to fall in and drown. Also, any persons who come in direct contact with the oily waste
pit are subject to severe eye and skin irritation due to very low pH (high acidity) of sludges in
the pit. In addition, exposed municipal and industrial wastes/debris on-site may also represent
minor physical hazards.
To determine whether persons in the site area are exposed to site-related contaminants, ATSDR evaluates the environmental and human exposure components that lead to human exposure. This pathways analysis consists of five elements: a source of contamination; environmental medium in which the contaminants may be present or may migrate; points of human exposures; routes of human exposure such as inhalation, ingestion, and dermal absorption; and a receptor population. The first three elements represent an environmental pathway and the last two elements represent a human exposure pathway.
ATSDR identifies an exposure pathway as completed, potential, or eliminated. Completed exposure pathways require that the five elements listed in the previous paragraph exist and indicate that exposure to a contaminant has occurred in the past, is currently occurring, or will occur in the future. Potential exposure pathways require that at least one of the five elements is missing but could exist. Potential pathways indicate that exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future. An exposure pathway can be eliminated if at least one of the five elements is missing and will never be present. Completed and potential exposure pathways may also be eliminated when they are no longer likely to exist or are not significant.
Completed and potential exposure pathways for the South 8th Street Landfill site are
summarized in Table 10 of this section. Estimates of the number of exposed persons for
completed exposure pathways and the number of potentially exposed persons for potential
exposure pathways is shown in Tables 11 and 12, respectively. The discussion that follows these
tables includes only those pathways that are believed to be important or relevant to the site.
However, exposure pathways that have been eliminated are also discussed.
Table 10. Completed and Potential Exposure Pathways
| Pathway Name | Exposure Pathway Elements | Time | ||||
| Source | Medium | Point of Exposure | Route of Exposure |
Exposed Population |
||
| Surface Soils | Wastes dumped
on site; site
flooding; stormwater runoff/drainage |
Surface Soil/Sediment | Contaminated soil areas | Skin contact Ingestion |
Trespassers; site visitors |
Past Future |
| Surface Water/ Sediment (On-site Pond) |
Wastes dumped
on-site; Site flooding; Stormwater runoff/drainage |
Surface Water; Sediments | On-site Pond | Skin contact Ingestion |
Waders/ swimmers (esp. guests of RV park) |
Past Future |
| Fish (On-site Pond) |
Surface water / sediment contamination (from site flooding; stormwater runoff/drainageetc.) | Fish | Residences or other places where fish are eaten | Ingestion | Consumers of fish from on-site pond | Past Future |
|
Potential Exposure Pathways | ||||||
| Waste Materials (Sludges) | Wastes dumped on-site | Sludges | Large oily sludge pit and other smaller pits | Skin contact Ingestion Inhalation |
Trespassers; site visitors |
Past Future |
| Ambient Air | Fugitive dusts and gaseous vapors from site wastes and contaminated soils | Air | Site areas and site perimeter | Inhalation | Trespassers; site visitors |
Past |
| Crops/Game | Contaminated site soils | Crops; Wild Game |
Residences or other places where crops and game are eaten | Ingestion | Consumers of crops grown on-site and wild game from site area | Past Present Future |
| Groundwater | Waste materials; contaminated soils | Groundwater | Future on-site water supply wells | Ingestion Skin contact |
Future site workers or recreational visitors | Future |
Table 11. Estimated Population for Completed Exposure Pathways
| ESTIMATED EXPOSED POPULATIONS THAT ARE AFFECTED BY A COMPLETED EXPOSURE PATHWAY* | ||||||
| EXPOSED POPULATIONS |
||||||
| Location | Est. Number |
VOCs (ex. toluene) |
Semi-Volatiles/PAHs (ex. benzo(a)-pyrene) |
PCBs | Pesticides (ex. DDT) |
Heavy Metals (ex. lead) |
| Trespassers; site visitors |
Not known | Surface Soil | Surface Soil | Surface Soil | Surface Soil | Surface Soil |
| Recreational users of on-site pond | Not known | Surface Water/ Sediment (on-site pond) |
Surface Water/ Sediment (on-site pond) |
Not exposed | Surface Water/ Sediment (on-site pond) |
Surface Water/ Sediment (on-site pond) |
| Persons who consume fish from the on-site pond | Not known | Exposure not likely | Fish (on-site pond) |
Fish (on-site pond) |
Fish (on-site pond) |
Fish (on-site pond) |
| * Refer to Table 10 for summary of completed exposure pathways. | ||||||
Table 12. Estimated Population for Potential Exposure Pathways
| ESTIMATED POTENTIALLY EXPOSED POPULATIONS THAT ARE AFFECTED BY A POTENTIAL EXPOSURE PATHWAY* | ||||||
| POTENTIALLY EXPOSED POPULATIONS |
||||||
| Est. Number |
VOCs (ex. toluene) |
Semi-Volatiles/PAHs (ex. benzo(a)-pyrene) |
PCBs | Pesticides (ex. DDT) |
Heavy Metals (ex. lead) | |
| Trespassers; site visitors |
Not known |
Waste Materials
(Sludges); Ambient Air |
Waste Materials
(Sludges); Ambient Air |
Waste Materials (Sludges); | Waste Materials (Sludges); | Waste Materials
(Sludges); Ambient Air |
| Consumers of crops grown on-site and wild game from site area | Not known | Exposure not likely | Crops/Game | Crops/Game | Crops/Game | Crops/Game |
| Future site workers or recreational visitors | Not known | Groundwater | Groundwater | Not exposed | Not exposed | Groundwater |
| * Refer to Table 10 for summary of potential exposure pathways. | ||||||
A. Completed Exposure Pathways
Surface Soil Pathway
Wide-spread contamination of surface soils on and around the South 8th Street Landfill has been documented by previous site investigations. Contaminants found in site surface soils included VOCs, PAHs, pesticides, and heavy metals. Surface soils were likely contaminated as a result of direct disposal of liquid and solid wastes, and transport of waste materials from the waste disposal areas (especially sludge pits) by site flooding and surface runoff.
Persons who accessed the site in the past, such as persons attending the annual city festival next to the site, guests of the adjacent RV park, and trespassers (including persons involved in on-site dumping activities), were likely exposed to contaminants in site surface soil. Exposure to surface soil contaminants would have occurred through skin contact and incidental ingestion. For small children (such as those from the neighboring RV park), soil ingestion can be an important exposure pathway due to their frequent hand-to-mouth contact. The maximum duration of exposure is estimated to be approximately 35 years since dumping at site reportedly began in the mid- to late-1950s and access to the site was unrestricted until 1992. Actual cumulative exposure, however, would likely have been significantly less since most persons would have accessed the site for short periods of time on an infrequent basis. The number of persons exposed to site contaminants and the extent of exposure and contaminant uptake cannot be estimated with the information currently available.
Field workers and other personnel who participated in any of the past site investigations, sampling events, or removal activities may have been exposed to site contaminants of concern via skin contact, inhalation, and incidental ingestion of waste materials and contaminated soils. However, it is likely that these investigative personnel utilized appropriate personal protective equipment, as necessary, during the various site activities. Therefore, any exposure of these persons to site contaminants was probably insignificant.
At present, most of the site is fenced and gated and public access to contaminated areas is restricted. Therefore, current exposure to contaminants in site surface soils is believed to be insignificant.
Future site workers, such as persons involved in site remediation activities, could be exposed to site contaminants unless appropriate personal protective equipment is utilized.
Surface Water/Sediment (On-site Pond) Pathway
Contaminants found in on-site waste materials and/or surface soils, including VOCs, PAHs, pesticides (DDT), and heavy metals, have also been detected in bottom sediments and surface water (metals only) of the on-site pond, located at the northeast end of the site. These findings and other available information suggest that contaminants from the site have been transported by flooding and surface runoff into the pond.
As previously discussed, it has been reported that the on-site pond was used in the past for wading, fishing, and possibly swimming, primarily by guests of the adjacent RV park. Persons who participated in these recreational activities were likely exposed to contaminants in the surface water and sediments. Past exposures were possible through skin contact and incidental ingestion. Since few contaminants other than metals were found in the bayou's surface waters and since most site contaminants, such as PAHs, DDT, and some heavy metals, tend to concentrate in the bottom sediments, exposure to the pond sediments is likely a much more significant exposure pathway.
At present, public access to the pond is restricted by a fence between the pond and the RV park. Therefore, the possibility of current exposure to contaminants in the pond surface water and sediments is remote.
Fish Pathway
As previously discussed, VOCs, PAHs, pesticides (DDT), and metals from the site have contaminated sediments in the on-site pond. Some of these contaminants, including pyrene, DDT, copper, mercury, and zinc, are known to bioconcentrate in fish tissue. In fact, these and other contaminants, such as PCB-1254, DDE, and DDT, have been found in fish tissue samples from the on-site pond. Contamination was found in several fish species including bluegill, largemouth bass, and channel catfish.
It has been reported that people have fished in the on-site pond in the past. Therefore, some of these persons -- the ones who ate their catch -- were likely exposed to contaminants in the fish. Other persons, such as family members, who also ate fish from the pond would have been likewise exposed. However, the number of persons exposed cannot be estimated with currently available information.
Currently, access to the on-site pond is restricted and no fishing is believed to be taking place.
B. Potential Exposure Pathways
Waste Materials (Sludges) Pathway
As previously discussed, oily, tar-like wastes (sludges) have been disposed of on-site in a large sludge pit in the central portion of the site and in several small depressions throughout the site. These waste sludges have been shown to contain significant levels of contaminants including include VOCs, PAHs, phenols, PCBs, pesticides, and heavy metals.
Site visitors/trespassers, site investigative personnel, and other persons who accessed the site in the past, may have been exposed to contaminants in the waste sludges through skin contact and incidental ingestion. In addition, future site workers could be exposed to sludge contaminants unless proper personal protective equipment is used.
Currently, there is little chance of direct exposure to contaminants in site sludges since these areas are fenced and gated. However, any person who does manage to access the restricted site areas could potentially contact the sludge materials. In addition, contaminants from the sludge areas (especially the large sludge pit) could be transported outside the restricted site areas (by floods or stormwater runoff) where human contact could occur. These transported contaminants could also contribute to other exposure pathways such as those involving the on-site pond (see previous discussion).
Ambient Air Pathway
As previously discussed, several volatile organic compounds (benzene, ethylbenzene, toluene, and xylenes (total)) were detected in ambient air samples collected at the site in October 1988. The contaminant air concentrations were more than three times greater than the background (upwind) samples. (Note: The presence of VOCs in the upwind samples was attributed to a nearby refinery (1).) Apparently, some PAHs were also found in the on-site air samples; however, data for these compounds could not be located. Volatile organic compounds, including 1,1-dichloroethene, methylene chloride, tetrachloroethene, and 1,1,1-trichloroethane, were also found in air emission flux samples collected at the site in August and September 1992 during the RI field activities.
Field personnel present during the October 1988 air sampling event, the 1992 RI sampling activities, and the other past site investigations may have been exposed to the contaminants described above via inhalation of vapors and/or fugitive dust. These persons may also have inhaled other air contaminants that were not sampled for. The significance of this potential exposure pathway is difficult to determine because 1) the number of contaminants reported was small, and 2) it is not known if respirators were worn by past on-site personnel. In addition, it is not known if persons off the site, such as guests of the adjacent RV park, were subject to exposure to air-borne contaminants from the site.
Although VOCs have been detected in air samples at the site, the levels were negligible except during intrusive trenching operations. This indicates that under current site conditions inhalation exposures to VOCs are not of concern, and that the greatest potential for human exposure to VOCs would be during remediation of the large sludge pit when the pit contents are disturbed. However, if appropriate measures are taken to minimize VOC emissions from the pit and to protect site workers during remediation of the pit, exposure to VOCs should not be a problem for persons on or off the site.
Crops/Game Pathway
Portions of the landfill site (in Area 1) are reported to have been used for agricultural purposes in the past (before the site was fenced). However, it is not known 1) what type of crops were grown on the site, 2) whether they were grown for human consumption, and 3) what levels of contaminants they contained. In addition, it is not known if the site will be used for agriculture in the future. During the RI field activities, ragweed seeds from the site were analyzed and found to contain only a few strongly bioaccumulative compounds. However, no plants suitable for human consumption were analyzed for site-related contaminants. As such, ATSDR cannot determine whether persons may be significantly exposed to contaminants from the ingestion of crops grown on the site. Therefore, this potential exposure pathway will not be considered further in this public health assessment.
It is possible that wild game, such as duck and deer, have come into contact with site contaminants through ingestion of contaminated water or foodstuffs (e.g., plants, fish). Any person who hunts and consumes such game could potentially be exposed to contaminants in the game meat. The existence of this potential exposure pathway, however, cannot be determined with currently available information; therefore, the pathway will not be discussed further.
Groundwater Pathway
As previously discussed, shallow groundwater at the South 8th Street Landfill site has been found to be contain heavy metals along with low levels of VOCs (including 1,2-dichloroethane, methylene chloride, and trichloroethene), PAHs, and pentachlorophenol. These findings and other available information indicate that contaminants were transferred to site groundwater from overlying soils and waste materials through stormwater infiltration/seepage.
The only reported private well in the site area is located approximately 250 feet east of the adjacent RV camping area. This well is generally considered to be sidegradient of the site. However, the well is not used for drinking water or other domestic uses. Therefore, human exposure to site-related contaminants from this well are unlikely. (Note: No sampling data for this well are available to determine whether the well is affected by contaminants from the site.)
It is possible that the South 8th Street Landfill site could eventually be developed for industrial or recreational uses (such as a state park), or it could be left abandoned. Under an industrial scenario, exposure to groundwater contaminants, through ingestion (drinking) and possibly dermal contact, could occur in the future if a shallow production well was installed on-site. Under a recreational scenario, future exposure could be possible, through ingestion (drinking), if the upper aquifer was used a source of potable water. However, as previously mentioned, future site remediation actions could reduce or eliminate these potential exposures.
As previously discussed, the nearest public water supply well, which is operated by the City of
West Memphis, is located approximately 2 miles upgradient of the site. Four other City of West
Memphis wells are located within 4 miles of the site. All of these wells are screened in the deep
Wilcox aquifer, about 1,300 feet below ground surface. None of the wells are expected to be
impacted by groundwater contamination from the site.
Introduction
Health effects resulting from the interaction of an individual with a hazardous substance in the environment depend on several factors. One is the route of exposure: that is, whether the chemical is breathed, consumed with food or water, or whether it contacts the skin. Another factor is the dose to which a person is exposed, and the amount of exposure dose that is actually absorbed. Mechanisms by which chemicals are altered in the environment, or inside the body once absorbed, are also important. Much variation in those mechanisms exists among individuals.
ATSDR has developed a Minimal Risk Level (MRL) for contaminants commonly found at hazardous waste sites. The MRL is an estimate of daily exposure to a contaminant below which non-cancer, adverse health effects are unlikely to occur. MRLs are developed for different routes of exposure, like inhalation and ingestion, and for length of exposure, such as acute (less than 14 days), intermediate (15 - 364 days), and chronic (365 days or greater). If an ATSDR MRL is not available as a health comparison value, then EPA's Reference Dose (RfD) is used. The RfD is an estimate of daily human exposure to a contaminant for a lifetime below which (non-cancer) health effects are unlikely to occur (7).
The completed exposure pathways discussed are our best estimates of possible scenarios based upon what we know about the history of the site. ATSDR has prepared toxicological profiles for many substances found at hazardous waste sites. Those documents present data and interpret information on the substances. Preparers of this public health assessment have reviewed the profiles for the contaminants of concern at the South 8th Street Landfill.
Trespassers and Site Visitors
ATSDR has determined that site visitors and trespassers (including persons involved in former on-site dumping activities), may have been exposed in the past to several contaminants in on-site pond water, pond sediments, fish caught in the on-site pond, surface soils, standing water, and non-pond sediments. Those contaminants are listed in Table 13. For purposes of evaluating this health assessment, we assume that trespassers were on the site no more than 36 days out of the year, and that they used the site for fishing, illegal dumping, and parking (especially during the annual Festival on the Levee).
Trespassers and visitors, both adults and children, may have been exposed to cobalt in the pond surface water and sediment, surface soil, non-pond surface water (standing water), and non-pond sediment. Cobalt is found in most rocks, soil, surface and underground water, plants and animals. Pure cobalt is a steel-gray, shiny, hard metal which does not dissolve in water, but some cobalt compounds (made by combining cobalt with other chemicals) will dissolve in water (8). Small amounts of cobalt are added to or naturally occur in foods. Vitamin B-12 contains cobalt and is essential for good health. ATSDR does not have any MRLs and EPA does not have an RfD for cobalt ingestion. Although dermatitis is a common result of dermal exposure to cobalt in humans, this effect is not expected to occur due to the low level of the contaminant in the media. (8) There have been no reported health effects from exposure to cobalt at the estimated exposure doses at the site. Therefore, no adverse health effects are expected from ingestion of surface water, sediment or soil containing cobalt.
Lead was detected in pond surface water and sediment, non-pond surface water and sediment, and surface soil. Lead exposure is particularly dangerous for unborn children and young children because they are more sensitive to it during their development (9). The American Academy of Pediatrics considers lead a significant hazard to the health of children in the United States. The Centers for Disease Control and Prevention (CDC) action level for lead in the blood of children is 10 µg/dl. ATSDR has no MRL, and EPA has no RfD for lead. Blood lead levels were not measured in adults or children who played on the site. Although it is not possible to determine whether illness or injury would result at the estimated dose of lead ingested because of the lack of health guidelines for comparison, exposures to lead in surface waters, sediments or soils at this site were probably limited. According to the toxicological profile for lead, no studies were found describing adverse health effects in humans resulting from dermal exposure to inorganic lead. (9) It is unlikely that lead at the site will cause illness or injury.
Aluminum, a silver-white, flexible metal, which is a natural element in the earth was detected in pond sediment, surface soil, and non-pond sediment. Many types of foods contain aluminum because they are grown in soil that contains aluminum. People normally eat about 10 milligrams of aluminum per day (10). Aluminum is used to make antacids, antiperspirants, and other drug store items. Exposure to aluminum is usually not harmful (10). ATSDR does not have any MRLs and EPA does not have an RfD for aluminum ingestion. Based on the levels seen no adverse health effects due to dermal contacted with the contaminated are expected to occur. There have been no reported health effects from exposure to aluminum at the estimated exposure dose at the site. No adverse health effects are expected from ingestion of or skin contact with surface soil, pond sediments, and non-pond sediments containing mercury.
Site visitors and trespassers fishing in the on-site pond were most likely exposed through ingestion to organic mercury in fish caught from the on-site pond. In the metal form, mercury is a shiny, silver-white, odorless liquid with a metallic taste. Mercury also occurs in an organic and inorganic form. Most of the information concerning neurotoxicity in humans following oral exposure to organic mercury comes from reports describing the effects of ingesting contaminated fish or fungicide treated grains. Because symptoms do not appear until weeks after the initial exposure, it is very difficult to establish a minimum dose resulting in adverse health effects in humans based on these poisonings. ATSDR has not derived MRLs for intermediate or chronic oral exposure to organic mercury (11). Although it is not possible to determine whether adverse health effects would occur at the estimated dose of organic mercury ingested due to lack of health guidelines for comparison, there was probably limited exposures to the mercury contaminated fish by site visitors and trespassers. Therefore, no adverse health effects are expected to occur.
Polycyclic aromatic hydrocarbon (PAH) compounds were also detected on the site. Phenanthrene was detected in the pond sediment, surface soil, and non-pond sediment. PAHs are a group of chemicals that are formed during the incomplete burning of coal, oil and gas, garbage, or other organic substances (12). They are found in the air, water and soil. The estimated exposure dose for ingestion of PAHs are lower than the acute MRL of 0.1 mg/kg/day. No illness or sickness is expected from the incidental ingestion of the PAHs in sediment or soil at the site. In addition, carcinogenic effects are not expected at the current concentrations of PAH compounds in the various site media. No studies were located regarding effects in humans following dermal exposure to the PAHs and no adverse health effects are expected from dermal contact with PAHs in soil or sediment (12).
Naphthalene and 2-methylnaphthalene were also detected in the surface soil on the site. Naphthalene is a white solid substance which smells like tar or mothballs (13). It evaporates easily and does not readily stay in soils or sediments. In water and soil, naphthalene is either destroyed by bacteria or it evaporates into the air within a few hours or days. Very little information is known about 2-methylnaphthalene. It is solid at room temperature and is used to make other chemicals used to make pesticides (13). ATSDR has no MRLs and EPA has no RfDs for naphthalene or 2-methylnaphthalene. However, illness occurs after ingestion of large quantities of naphthalene. The estimated exposure dose was very low and should lead to no adverse health effects. No adverse health effects are expected to occur due to dermal contact with naphthalene in the surface soils at the most recent concentration given. (13) It is not possible to determine whether adverse health effects are expected from exposure to 2-methylnaphthalene at the estimated dose.
Volatile organic compounds (VOCs) detected at the site included 1,1,1-trichloroethane and chloromethane. 1,1,1-trichloroethane, which was found in site surface soil, is a man-made chemical that does not occur naturally. (14) There are no MRLs or RfDs for 1,1,1-trichloroethane ingestion. However, exposure at the estimated doses is not expected to cause any adverse health effects. No adverse health effects are expected to occur due to dermal contact with 1,1,1-trichloroethane in surface soils. (14)
Chloromethane is a clear, colorless gas that is hard to smell. It was detected in the on-site pond sediments. It has a slightly sweet, non-irritating odor at high levels in the air. It is a naturally occurring chemical that is made in large amounts in the oceans and is produced by some plants and rotting wood and when grass, wood, charcoal, and coal burn (15). Chloromethane will also evaporate from the soil surface. Only one study was found regarding the effects of chloromethane ingestion. Rats were given a large dose (420 mg/kg) and the livers were examined for effects. No liver damage was observed in those animals. No other studies were located regarding health effects in humans or animals after oral exposure to chloromethane. Although it is not possible to determine whether adverse health effects are expected from ingestion, the estimated exposure dose for chloromethane ingestion was quite low. According to the toxicological profile for chloromethane (15), no studies were located regarding systemic and carcinogenic effects in humans after dermal exposure to chloromethane.
ATSDR does not have Toxicological Profiles for dibenzofuran and carbazole. Therefore, it is
not possible to determine whether any adverse health effects are expected from exposure to those
compounds.
Table 13. Comparison of Estimated Exposed Dose to Health Guidelines for Trespassers Exposed to On-Site Contaminants
| Contaminant | Exposure Medium | Health Guideline (mg/kg/day) | ||
| Value | Source | Exceeded by Estimated Exposed Dose | ||
| Cobalt | Surface Soil Pond Water Pond Sediments Standing Water Non-Pond Sediments |
None | None | None |
| Lead | Surface Soil Pond Water Pond Sediments Standing Water Non-Pond Sediments |
None | None | None |
| Aluminum | Surface Soil Pond Sediments Non-Pond Sediments |
None | None | None |
| Mercury (organic) | Fish | None | None | None |
| PAHs | Surface Soil Pond Sediments Non-Pond Sediments |
None | None | None |
| Naphthalene | Surface Soil | None | None | None |
| 2-Methylnaphthalene | Surface Soil | None | None | None |
| 1,1,1-Trichloroethane | Surface Soil | None | None | None |
| Chloromethane | Pond Sediments | None | None | None |
| Dibenzofuran | Surface Soil | None | None | None |
| Carbazole | Surface Soil | None | None | None |
RV Park Guests
ATSDR has determined that guests of the RV park (located adjacent to the site) may in the past have been exposed to several contaminants in on-site pond water, pond sediments, and fish caught in the on-site pond. Those contaminants are listed in Table 14. The contaminants will be discussed by source of exposure.
Pond Surface Water
The concentration of cobalt in surface water does not exceed the naturally occurring background levels of cobalt. Fifty times this value maybe found in groundwater near mineral deposits. For a child or adult incidentally consuming surface water during recreational activities, no adverse health effects are expected to occur.
The concentration of lead in the pond surface water does not exceed regional background concentrations. Due to the limited contact with the surface water, that a child or adult might have during swimming or wading, there are no adverse health effects expected to occur from this exposure.
Pond Sediments
ATSDR or EPA does not have a comparison value for a number of contaminants found in the pond sediment, including chloromethane, phenanthrene, aluminum, cobalt, and lead. The concentrations found in the sediment were extremely low except for aluminum. Incidental ingestion of these contaminants during swimming and wading seems to be very limited. Based on this limited potential for exposure, a child or adult wading or swimming in the pond should not experience any adverse health effects.
Fish
RV park guests fishing in the on-site pond were most likely exposed through ingestion to organic mercury in fish caught from the on-site pond. Most of the information concerning neurotoxicity in humans following oral exposure to organic mercury comes from reports describing the effects of ingesting contaminated fish or fungicide treated grains. Because symptoms do not appear until weeks after the initial exposure, it is very difficult to establish a minimum dose resulting in adverse health effects in humans based on these poisonings. ATSDR has not derived MRLs for intermediate or chronic oral exposure to organic mercury (11).
The average concentration of mercury in fish is less than 0.2 ug/g. The mercury concentration in the fish in the on-site pond exceed this concentration to a significant degree indicating that the fish in the pond have bioaccumulated mercury from the contaminating waste. Primarily, mercury exists in fish tissue as organic mercury. Organic mercury compounds are more readily absorbed by the oral route than inorganic mercury. In humans, approximately 95% of the ingested organic mercury is absorbed from the gastrointestinal tract (11).
Although it is not possible to determine whether adverse health effects would occur at the estimated dose of organic mercury ingested due to lack of health guidelines for comparison, there was probably limited exposures to the mercury contaminated fish by RV park guests. Therefore, no adverse health effects are expected to occur.
Table 14. Comparison of Estimated Exposed Dose to Health Guidelines for RV Park Guests Exposed to On-Site Contaminants
| Contaminant | Exposure Medium | Health Guideline (mg/kg/day) | ||
| Value | Source | Exceeded by Estimated Exposed Dose | ||
| Cobalt | Pond Water Pond Sediments |
None | None | None |
| Lead | Pond Water Pond Sediments |
None | None | None |
| Chloromethane | Pond Sediments | None | None | None |
| PAHs | Pond Sediments | None | None | None |
| Aluminum | Pond Sediments | None | None | None |
| Mercury (organic) | Fish | None | None | None |
B. Health Outcome Data Evaluation
Health outcome data were not evaluated for this site because the population of concern is small (about 5 - 100), mostly transient, and exposures to site contaminants were intermittent. This would make it very unlikely that any health effects due to the site could be detected. In addition, no previous health studies on the populations near the South 8th Street Landfill site were identified during the gathering of data and information for this public health assessment. Furthermore, no community concerns were expressed regarding any possible health outcomes.
If health outcome data relevant to the South 8th Street Landfill site and the surrounding community should become available at a later date, ATSDR will evaluate its significance at that time.
C. Community Health Concerns Evaluation
No community health concerns about the South 8th Street Landfill were expressed by citizens or public health officials during the gathering of the information used to prepare this public health assessment.
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