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 conductedpreviously at the site and identifies contaminants of concern found in specific environmentalmedia. The selected contaminants are evaluated in subsequent sections of the health assessmentto determine whether exposure to them has public health significance.
ATSDR selects contaminants for further evaluation based upon the following factors:
- concentrations of contaminants on and off the site;
- sampling locations and frequency, field data quality, and laboratory data quality;
- comparison of on-site and off-site concentrations with health assessment comparison values for non-carcinogenic and/or carcinogenic endpoints; and
- community health concerns.
It is emphasized that identification of a contaminant of concern in this section does not mean thatexposure to it will cause adverse health effects. As mentioned above, the potential for adversehealth 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 inspecific media that are used to select contaminants for further evaluation. The values provideguidelines used to estimate a dose at which health effects might be observed. Comparisonvalues, along with acronyms and abbreviations, used in the Environmental Contamination andOther Hazards and the Public Health Implications sections of this public health assessment arelisted 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)
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 EvaluationGuide (RMEGs) are based on EPA Reference Doses (RfDs) and factor in body weight andingestion rates.
Lifetime Health Advisories (LTHAs) represent contaminant concentrations that theEnvironmental Protection Agency (EPA) deems protective of public health (taking intoconsideration the availability and economics of water treatment technology) over a lifetime (70years) 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 deemsprotective of public health (considering the availability and economics of water treatmenttechnology) 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 atwhich no known or anticipated adverse effect on the health of persons occurs and which allowsan 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 thepopulation. 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 isunlikely 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 belowwhich non-cancer, adverse health effects are unlikely to occur. MRLs are developed for eachroute of exposure, such as ingestion and inhalation, and for the length of exposure.
As previously discussed, sampling data have been collected from various environmental mediaon 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 in1992. RI activities included the following: (1) digging of shallow trenches and sampling ofsubsurface soil from the trenches; (2) drilling and installation of monitoring wells; (3) collectionof surface soil and surface sediment samples from on and off site areas; (4) groundwatersampling of the monitoring wells; (5) collection of sludge solids and liquids from the large, oilysludge pit; (6) collection of surface water and sediment samples from the on-site pond at thenortheast 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 thesite. Most of the samples collected during the RI were analyzed for volatile organic compounds(VOCs), semi-volatile compound such as polycyclic aromatic hydrocarbons (PAHs) andphenols, 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 arelimited but are also evaluated where possible. For the purpose of this health assessment, "on-siteincludes 1) the three fenced areas (Areas 1, 2, and 3); 2) the area along the Mississippi Riveroutside of the site fencing, and 3) the dirt-road portion of South 8th Street passing through thesite. All other areas (e.g., the RV park) are considered "off-site". These designations aregenerally consistent with the those utilized in the RI.
During the 1992 RI, samples of sludge solids and liquids from the large, oily sludge pit werecollected 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 concentrationsin the site area; others, such as barium, cyanide, lead, mercury, and zinc, exceed background soillevels.
The liquid sample (sludge pit water) contained significantly fewer contaminants than the sludgesolids samples. Contaminants detected in the liquid sample included VOCs, phenols, and metals(Table 1b.)
|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|
Approximately 40 surface soil samples were collected at the site during the 1992 RemedialInvestigation (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 someVOCs, 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 valuesor 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 detectedwere greater than background surface soil levels in the site area.
|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 monitoringwells 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 shallowwells were designed to monitor the water quality near the surface of the aquifer and to assess theground water gradient and flow pattern in the vicinity of the site. The other two wells, MW-3Dand 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 toevaluate potential downward migration of contaminants. The monitoring well locations areshown in Figure 6 (6).
The first round of groundwater samples were collected in October 1992 upon completion of themonitoring well installation. During this sampling event, the predominant groundwater flowwas from northwest to southeast (i.e., towards the river). A second, confirmatory round ofsamples were collected in April 1993 when the groundwater flow direction was from thesouthwest 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 foundat low levels in the October 1992 and April 1993 groundwater samples. However, no volatilecompounds were found in the April 1993 samples. Several metals were detected in the firstround of samples, including arsenic, cobalt, and lead, at concentrations greater than the levelsmeasured in the background monitoring wells. In the second round of samples, metals weremeasured at generally lower levels. However, since the groundwater flow direction wassignificantly different during the first and second sampling rounds, comparison of the two datasets may not be very meaningful.
|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|
Four surface water samples were collected from the on-site pond, located at the northeast edge ofthe 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 ofconcern found in the pond surface water samples (Table 4).
|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|
During the RI, five samples of sediment from the on-site pond were collected and analyzed forVOCs, semi-volatiles, PCBs, pesticides, and metals. The sediment sampling locations are shownin 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, andzinc) were found in the sediments. VOCs (chlorobenzene and chloromethane) and DDT werealso detected; however, the levels of chlorobenzene and DDT did not exceed ATSDR'scomparison values.
In August and September 1992, an ecological characterization of the site was conducted by anEPA 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) werecollected 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.
|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 samples were collected at the site in October 1988. Upwind and downwind airsamples were reportedly taken at seven stations (1); however, the exact location of thesesampling stations cannot be determined from currently available information.
As shown in Table 7a, benzene, ethylbenzene, toluene, and xylenes were detected in thedownwind 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 hasbeen reported that other contaminants, such as PAHs and metals, were also detected in theOctober 1988 air samples. No sampling data for these contaminants, however, was found toconfirm their presence.
During the 1992 RI, air samples were collected for VOCs using emission isolation fluxchambers. Several samples, including 2 blanks, were collected from undisturbed locations priorto the excavation of exploratory trenches and from the disturbed areas during the trenchingoperations. The sampling locations are shown in Figure 7.
As shown in Table 7b, the following VOCs were found in the air samples at levels exceedingATSDR comparison values: benzene, 1,1-dichloroethene, methylene chloride, andtetrachloroethene. Toluene and 1,1,1-trichloroethane were also detected but not at levels inexcess of ATSDR comparison values.
|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)|
|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)|
Off-site surface soil samples were collected at five locations during the RI and analyzed forVOCs, semi-volatiles, phenols, PCBs, pesticides, and metals. The locations of these samples areindicated in Figure 5. Two of these sampling locations were upgradient of the site (north of theRV park), one was downgradient of the site near the old farm field, one was across the leveenear 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 surfacesoil samples. In general, the contaminant levels were significantly lower than levels in on-sitesurface soils, and in many cases did not exceed ATSDR's comparison values.
|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 MonitoringWells 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 RVpark. During low-to-normal river water levels, which were present during the October 1992sampling activities, these two wells are considered to be upgradient of the site and, therefore, arereferred to as "background" wells. However, during high river water levels, such as those thatoccurred during the April 1993 sampling events, these wells may actually be cross-gradient ordown-gradient of the site. MW-5, with a depth of 40 feet, is located at the City of WestMemphis 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 wellswere bis(2-ethylhexyl)phthalate, di-n-butylphthalate, and di-n-octylphthalate, which were foundduring both sampling rounds. Metals were generally found at levels similar to or less than thelevels measured in on-site monitoring wells. In addition, the levels of metals in the April 1993samples were generally lower than the levels in the October 1992 samples. An exception to thistrend was mercury which was detected (5.8 ug/L) in the second round of samples but not in thefirst round. Note: Since the groundwater flow direction was significantly different during thefirst 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 publicwells in the general site area were located during the development of this public health assessment.
|Reference|| Comparison |
|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|
The only major waterbody in the site area is the Mississippi River which borders the site on thesoutheast. Two surface water samples, one upstream of the site and one downstream, werecollected from the river in April 1993. No pesticides, PCBs, or other organic compounds weredetected in the surface water samples. Metal levels found downstream of the site were generallysimilar to the levels upstream of the site. These limited data suggest that contaminants from thesite are not significantly impacting the Mississippi River. Moreover, site contamination is not expected to significantly affect the river since 1) stormwaterrunoff generally remains on-site and does not enter the river, and, therefore, contaminants insurface 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 tobe migrating into the river; and 3) the extremely large river flow would greatly dilute anycontaminants entering the river from site drainage, flooding, and/or groundwater, especiallyduring 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 ofthis health assessment. However, for the reasons given above, river sediments are unlikely to besignificantly impacted by contaminants from the site.
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, towhat extent they may have been affected by contaminants from the site. In addition, no off-siteair samples were collected during the 1992 RI. No other information regarding off-site levels ofair-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 chemicalsto the environment (air, water, land, or underground injection) by certain industries and is basedon data collected by the EPA.
To identify facilities that could contribute to the air, surface water, and soil contamination nearthe South 8th Street Landfill, ATSDR searched the 1987, 1988, 1989, and 1990 TRI. Thissearch revealed that various toxic chemicals had been released to surface water and air byindustries in the West Memphis area. These releases included wastewater discharges to theMississippi River. However, it cannot be determined from the TRI information whether thesereleases have contributed to contamination at the site or whether persons in the site area havebeen exposed to contaminants from the releases. Therefore, the results from the TRI search arenot considered further in this public health assessment.
The June 1993 RI report indicates that the RI data collection, handling, and analysis activitieswere conducted in accordance with the quality assurance/ quality control (QA/QC) requirementsof 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 datauseability criteria and data quality indicators.
Validation of the RI/FS data was conducted by an EPA contract lab in accordance with theRI/FS WP, QAPP, and EPA guidelines. Validated data packages included the documentationreview of QA/QC samples such as field duplicates, blanks, rinsate, and matrix spike/matrix spikeduplicates. The data validation assessment demonstrated that the analytical results for RI/FSsamples 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 toitems such as interference from high concentration samples, outlying calibration data, or lowsurrogate recoveries. However, the overall impact on the data quality is not considered to besignificant.
Physical hazards present at the site include the large oily waste pit, which contains tar-likesubstances, 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 smallchildren, to fall in and drown. Also, any persons who come in direct contact with the oily wastepit are subject to severe eye and skin irritation due to very low pH (high acidity) of sludges inthe pit. In addition, exposed municipal and industrial wastes/debris on-site may also representminor physical hazards.
To determine whether persons in the site area are exposed to site-related contaminants, ATSDRevaluates the environmental and human exposure components that lead to human exposure. Thispathways analysis consists of five elements: a source of contamination; environmental mediumin which the contaminants may be present or may migrate; points of human exposures; routes ofhuman 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 representa human exposure pathway.
ATSDR identifies an exposure pathway as completed, potential, or eliminated. Completedexposure pathways require that the five elements listed in the previous paragraph exist andindicate that exposure to a contaminant has occurred in the past, is currently occurring, or willoccur in the future. Potential exposure pathways require that at least one of the five elements ismissing but could exist. Potential pathways indicate that exposure to a contaminant could haveoccurred in the past, could be occurring now, or could occur in the future. An exposure pathwaycan 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 longerlikely to exist or are not significant.
Completed and potential exposure pathways for the South 8th Street Landfill site aresummarized in Table 10 of this section. Estimates of the number of exposed persons forcompleted exposure pathways and the number of potentially exposed persons for potentialexposure pathways is shown in Tables 11 and 12, respectively. The discussion that follows thesetables 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.
|Pathway Name||Exposure Pathway Elements||Time|
|Source||Medium||Point of Exposure||Route of|
|Completed Exposure Pathways|
|Surface Soils||Wastes dumpedon site; siteflooding;|
|SurfaceSoil/Sediment||Contaminated soilareas||Skin contact|
|Surface Water;Sediments||On-site Pond||Skin contact|
swimmers(esp. guests ofRV park)
|Surface water /sedimentcontamination(from siteflooding;stormwaterrunoff/drainageetc.)||Fish||Residences orother places wherefish are eaten||Ingestion||Consumers offish from on-site pond||Past|
|Potential Exposure Pathways|
|Waste Materials(Sludges)||Wastes dumpedon-site||Sludges||Large oily sludgepit and othersmaller pits||Skin contact|
|Ambient Air||Fugitive dustsand gaseousvapors from sitewastes andcontaminatedsoils||Air||Site areas and siteperimeter||Inhalation||Trespassers;|
|Residences orother places wherecrops and game areeaten||Ingestion||Consumers ofcrops grownon-site andwild gamefrom site area||Past|
|Groundwater||Wastematerials;contaminatedsoils||Groundwater||Future on-sitewater supply wells||Ingestion|
|Future siteworkers orrecreationalvisitors||Future|
|ESTIMATED EXPOSED POPULATIONS THAT ARE AFFECTED BY A COMPLETED EXPOSURE PATHWAY*|
|COMPLETED EXPOSURE PATHWAY FOR:|
|Notknown||Surface Soil||Surface Soil||Surface Soil||Surface Soil||Surface Soil|
|Recreationalusers of on-sitepond||Notknown||Surface Water/|
|Not exposed||Surface Water/|
|Persons whoconsume fishfrom the on-sitepond||Notknown||Exposure notlikely||Fish|
|* Refer to Table 10 for summary of completed exposure pathways.|
|ESTIMATED POTENTIALLY EXPOSED POPULATIONS THAT ARE AFFECTED BY A POTENTIAL EXPOSUREPATHWAY*|
|POTENTIAL EXPOSURE PATHWAY FOR:|
|Waste Materials(Sludges);||Waste Materials(Sludges);||Waste Materials(Sludges);|
|Consumers ofcrops grown on-site and wildgame from sitearea||Notknown||Exposure notlikely||Crops/Game||Crops/Game||Crops/Game||Crops/Game|
|Future siteworkers orrecreationalvisitors||Notknown||Groundwater||Groundwater||Not exposed||Not exposed||Groundwater|
|* Refer to Table 10 for summary of potential exposure pathways.|
Surface Soil Pathway
Wide-spread contamination of surface soils on and around the South 8th Street Landfill has beendocumented by previous site investigations. Contaminants found in site surface soils includedVOCs, PAHs, pesticides, and heavy metals. Surface soils were likely contaminated as a result ofdirect disposal of liquid and solid wastes, and transport of waste materials from the wastedisposal 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 nextto the site, guests of the adjacent RV park, and trespassers (including persons involved in on-sitedumping activities), were likely exposed to contaminants in site surface soil. Exposure tosurface 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 animportant exposure pathway due to their frequent hand-to-mouth contact. The maximumduration of exposure is estimated to be approximately 35 years since dumping at site reportedlybegan in the mid- to late-1950s and access to the site was unrestricted until 1992. Actualcumulative exposure, however, would likely have been significantly less since most personswould have accessed the site for short periods of time on an infrequent basis. The number ofpersons exposed to site contaminants and the extent of exposure and contaminant uptake cannotbe 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 concernvia skin contact, inhalation, and incidental ingestion of waste materials and contaminated soils. However, it is likely that these investigative personnel utilized appropriate personal protectiveequipment, as necessary, during the various site activities. Therefore, any exposure of thesepersons to site contaminants was probably insignificant.
At present, most of the site is fenced and gated and public access to contaminated areas isrestricted. Therefore, current exposure to contaminants in site surface soils is believed to beinsignificant.
Future site workers, such as persons involved in site remediation activities, could be exposed tosite 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 surfacewater (metals only) of the on-site pond, located at the northeast end of the site. These findingsand other available information suggest that contaminants from the site have been transported byflooding and surface runoff into the pond.
As previously discussed, it has been reported that the on-site pond was used in the past forwading, fishing, and possibly swimming, primarily by guests of the adjacent RV park. Personswho participated in these recreational activities were likely exposed to contaminants in thesurface water and sediments. Past exposures were possible through skin contact and incidentalingestion. Since few contaminants other than metals were found in the bayou's surface watersand since most site contaminants, such as PAHs, DDT, and some heavy metals, tend toconcentrate in the bottom sediments, exposure to the pond sediments is likely a much moresignificant 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 andsediments is remote.
As previously discussed, VOCs, PAHs, pesticides (DDT), and metals from the site havecontaminated 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 andother contaminants, such as PCB-1254, DDE, and DDT, have been found in fish tissue samplesfrom 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 ofthese 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 beenlikewise exposed. However, the number of persons exposed cannot be estimated with currentlyavailable information.
Currently, access to the on-site pond is restricted and no fishing is believed to be taking place.
Waste Materials (Sludges) Pathway
As previously discussed, oily, tar-like wastes (sludges) have been disposed of on-site in a largesludge 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 includinginclude VOCs, PAHs, phenols, PCBs, pesticides, and heavy metals.
Site visitors/trespassers, site investigative personnel, and other persons who accessed the site inthe past, may have been exposed to contaminants in the waste sludges through skin contact andincidental ingestion. In addition, future site workers could be exposed to sludge contaminantsunless proper personal protective equipment is used.
Currently, there is little chance of direct exposure to contaminants in site sludges since theseareas are fenced and gated. However, any person who does manage to access the restricted siteareas could potentially contact the sludge materials. In addition, contaminants from the sludgeareas (especially the large sludge pit) could be transported outside the restricted site areas (byfloods or stormwater runoff) where human contact could occur. These transported contaminantscould also contribute to other exposure pathways such as those involving the on-site pond (seeprevious 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 anearby 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, including1,1-dichloroethene, methylene chloride, tetrachloroethene, and 1,1,1-trichloroethane, were alsofound in air emission flux samples collected at the site in August and September 1992 during theRI field activities.
Field personnel present during the October 1988 air sampling event, the 1992 RI samplingactivities, and the other past site investigations may have been exposed to the contaminantsdescribed above via inhalation of vapors and/or fugitive dust. These persons may also haveinhaled other air contaminants that were not sampled for. The significance of this potentialexposure pathway is difficult to determine because 1) the number of contaminants reported wassmall, and 2) it is not known if respirators were worn by past on-site personnel. In addition, it isnot known if persons off the site, such as guests of the adjacent RV park, were subject toexposure to air-borne contaminants from the site.
Although VOCs have been detected in air samples at the site, the levels were negligible exceptduring intrusive trenching operations. This indicates that under current site conditions inhalationexposures to VOCs are not of concern, and that the greatest potential for human exposure toVOCs 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 toprotect site workers during remediation of the pit, exposure to VOCs should not be a problemfor persons on or off the site.
Portions of the landfill site (in Area 1) are reported to have been used for agricultural purposesin the past (before the site was fenced). However, it is not known 1) what type of crops weregrown on the site, 2) whether they were grown for human consumption, and 3) what levels ofcontaminants they contained. In addition, it is not known if the site will be used for agriculturein the future. During the RI field activities, ragweed seeds from the site were analyzed andfound to contain only a few strongly bioaccumulative compounds. However, no plants suitablefor human consumption were analyzed for site-related contaminants. As such, ATSDR cannotdetermine whether persons may be significantly exposed to contaminants from the ingestion ofcrops grown on the site. Therefore, this potential exposure pathway will not be consideredfurther in this public health assessment.
It is possible that wild game, such as duck and deer, have come into contact with sitecontaminants through ingestion of contaminated water or foodstuffs (e.g., plants, fish). Anyperson who hunts and consumes such game could potentially be exposed to contaminants in thegame meat. The existence of this potential exposure pathway, however, cannot be determinedwith currently available information; therefore, the pathway will not be discussed further.
As previously discussed, shallow groundwater at the South 8th Street Landfill site has beenfound to be contain heavy metals along with low levels of VOCs (including 1,2-dichloroethane,methylene chloride, and trichloroethene), PAHs, and pentachlorophenol. These findings andother available information indicate that contaminants were transferred to site groundwater fromoverlying soils and waste materials through stormwater infiltration/seepage.
The only reported private well in the site area is located approximately 250 feet east of theadjacent 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, humanexposure to site-related contaminants from this well are unlikely. (Note: No sampling data forthis 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 industrialor recreational uses (such as a state park), or it could be left abandoned. Under an industrialscenario, exposure to groundwater contaminants, through ingestion (drinking) and possiblydermal 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), ifthe upper aquifer was used a source of potable water. However, as previously mentioned, futuresite remediation actions could reduce or eliminate these potential exposures.
As previously discussed, the nearest public water supply well, which is operated by the City ofWest Memphis, is located approximately 2 miles upgradient of the site. Four other City of WestMemphis wells are located within 4 miles of the site. All of these wells are screened in the deepWilcox aquifer, about 1,300 feet below ground surface. None of the wells are expected to beimpacted by groundwater contamination from the site.
Health effects resulting from the interaction of an individual with a hazardous substance in theenvironment depend on several factors. One is the route of exposure: that is, whether thechemical is breathed, consumed with food or water, or whether it contacts the skin. Anotherfactor is the dose to which a person is exposed, and the amount of exposure dose that is actuallyabsorbed. Mechanisms by which chemicals are altered in the environment, or inside the bodyonce absorbed, are also important. Much variation in those mechanisms exists amongindividuals.
ATSDR has developed a Minimal Risk Level (MRL) for contaminants commonly found athazardous waste sites. The MRL is an estimate of daily exposure to a contaminant below whichnon-cancer, adverse health effects are unlikely to occur. MRLs are developed for differentroutes of exposure, like inhalation and ingestion, and for length of exposure, such as acute (lessthan 14 days), intermediate (15 - 364 days), and chronic (365 days or greater). If an ATSDRMRL 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 basedupon what we know about the history of the site. ATSDR has prepared toxicological profiles formany substances found at hazardous waste sites. Those documents present data and interpretinformation on the substances. Preparers of this public health assessment have reviewed theprofiles 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 formeron-site dumping activities), may have been exposed in the past to several contaminants in on-sitepond water, pond sediments, fish caught in the on-site pond, surface soils, standing water, andnon-pond sediments. Those contaminants are listed in Table 13. For purposes of evaluating thishealth assessment, we assume that trespassers were on the site no more than 36 days out of theyear, and that they used the site for fishing, illegal dumping, and parking (especially during theannual Festival on the Levee).
Trespassers and visitors, both adults and children, may have been exposed to cobalt in the pondsurface water and sediment, surface soil, non-pond surface water (standing water), and non-pondsediment. Cobalt is found in most rocks, soil, surface and underground water, plants andanimals. Pure cobalt is a steel-gray, shiny, hard metal which does not dissolve in water, butsome 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 containscobalt and is essential for good health. ATSDR does not have any MRLs and EPA does nothave an RfD for cobalt ingestion. Although dermatitis is a common result of dermal exposure tocobalt in humans, this effect is not expected to occur due to the low level of the contaminant inthe media. (8) There have been no reported health effects from exposure to cobalt at theestimated exposure doses at the site. Therefore, no adverse health effects are expected fromingestion 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 youngchildren because they are more sensitive to it during their development (9). The AmericanAcademy of Pediatrics considers lead a significant hazard to the health of children in the UnitedStates. The Centers for Disease Control and Prevention (CDC) action level for lead in the bloodof children is 10 µg/dl. ATSDR has no MRL, and EPA has no RfD for lead. Blood lead levelswere not measured in adults or children who played on the site. Although it is not possible todetermine whether illness or injury would result at the estimated dose of lead ingested because ofthe lack of health guidelines for comparison, exposures to lead in surface waters, sediments orsoils at this site were probably limited. According to the toxicological profile for lead, nostudies were found describing adverse health effects in humans resulting from dermal exposureto 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 inpond sediment, surface soil, and non-pond sediment. Many types of foods contain aluminumbecause they are grown in soil that contains aluminum. People normally eat about 10 milligramsof aluminum per day (10). Aluminum is used to make antacids, antiperspirants, and other drugstore items. Exposure to aluminum is usually not harmful (10). ATSDR does not have anyMRLs and EPA does not have an RfD for aluminum ingestion. Based on the levels seen noadverse 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 exposuredose at the site. No adverse health effects are expected from ingestion of or skin contact withsurface soil, pond sediments, and non-pond sediments containing mercury.
Site visitors and trespassers fishing in the on-site pond were most likely exposed throughingestion to organic mercury in fish caught from the on-site pond. In the metal form, mercury isa shiny, silver-white, odorless liquid with a metallic taste. Mercury also occurs in an organicand inorganic form. Most of the information concerning neurotoxicity in humans following oralexposure to organic mercury comes from reports describing the effects of ingestingcontaminated fish or fungicide treated grains. Because symptoms do not appear until weeksafter the initial exposure, it is very difficult to establish a minimum dose resulting in adversehealth effects in humans based on these poisonings. ATSDR has not derived MRLs forintermediate or chronic oral exposure to organic mercury (11). Although it is not possible todetermine whether adverse health effects would occur at the estimated dose of organic mercuryingested due to lack of health guidelines for comparison, there was probably limited exposuresto the mercury contaminated fish by site visitors and trespassers. Therefore, no adverse healtheffects 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. PAHsare 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. Theestimated 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 soilat the site. In addition, carcinogenic effects are not expected at the current concentrations ofPAH compounds in the various site media. No studies were located regarding effects in humansfollowing dermal exposure to the PAHs and no adverse health effects are expected from dermalcontact 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 evaporateseasily and does not readily stay in soils or sediments. In water and soil, naphthalene is eitherdestroyed by bacteria or it evaporates into the air within a few hours or days. Very littleinformation is known about 2-methylnaphthalene. It is solid at room temperature and is used tomake other chemicals used to make pesticides (13). ATSDR has no MRLs and EPA has noRfDs for naphthalene or 2-methylnaphthalene. However, illness occurs after ingestion of largequantities of naphthalene. The estimated exposure dose was very low and should lead to noadverse health effects. No adverse health effects are expected to occur due to dermal contactwith naphthalene in the surface soils at the most recent concentration given. (13) It is notpossible 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 andchloromethane. 1,1,1-trichloroethane, which was found in site surface soil, is a man-madechemical 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 anyadverse health effects. No adverse health effects are expected to occur due to dermal contactwith 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 pondsediments. It has a slightly sweet, non-irritating odor at high levels in the air. It is a naturallyoccurring chemical that is made in large amounts in the oceans and is produced by some plantsand rotting wood and when grass, wood, charcoal, and coal burn (15). Chloromethane will alsoevaporate from the soil surface. Only one study was found regarding the effects ofchloromethane ingestion. Rats were given a large dose (420 mg/kg) and the livers wereexamined for effects. No liver damage was observed in those animals. No other studies werelocated 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 fromingestion, the estimated exposure dose for chloromethane ingestion was quite low. According tothe toxicological profile for chloromethane (15), no studies were located regarding systemic andcarcinogenic effects in humans after dermal exposure to chloromethane.
ATSDR does not have Toxicological Profiles for dibenzofuran and carbazole. Therefore, it isnot possible to determine whether any adverse health effects are expected from exposure to thosecompounds.
RV Park Guests
ATSDR has determined that guests of the RV park (located adjacent to the site) may in the pasthave been exposed to several contaminants in on-site pond water, pond sediments, and fishcaught in the on-site pond. Those contaminants are listed in Table 14. The contaminants will bediscussed by source of exposure.
Pond Surface Water
The concentration of cobalt in surface water does not exceed the naturally occurringbackground levels of cobalt. Fifty times this value maybe found in groundwater nearmineral deposits. For a child or adult incidentally consuming surface water duringrecreational activities, no adverse health effects are expected to occur.
The concentration of lead in the pond surface water does not exceed regional backgroundconcentrations. Due to the limited contact with the surface water, that a child or adultmight have during swimming or wading, there are no adverse health effects expected tooccur from this exposure.
ATSDR or EPA does not have a comparison value for a number of contaminants foundin the pond sediment, including chloromethane, phenanthrene, aluminum, cobalt, andlead. The concentrations found in the sediment were extremely low except for aluminum. Incidental ingestion of these contaminants during swimming and wading seems to bevery limited. Based on this limited potential for exposure, a child or adult wading orswimming in the pond should not experience any adverse health effects.
RV park guests fishing in the on-site pond were most likely exposed through ingestion toorganic mercury in fish caught from the on-site pond. Most of the informationconcerning neurotoxicity in humans following oral exposure to organic mercury comesfrom reports describing the effects of ingesting contaminated fish or fungicide treatedgrains. Because symptoms do not appear until weeks after the initial exposure, it is verydifficult to establish a minimum dose resulting in adverse health effects in humans basedon these poisonings. ATSDR has not derived MRLs for intermediate or chronic oralexposure to organic mercury (11).
The average concentration of mercury in fish is less than 0.2 ug/g. The mercuryconcentration in the fish in the on-site pond exceed this concentration to a significantdegree indicating that the fish in the pond have bioaccumulated mercury from thecontaminating waste. Primarily, mercury exists in fish tissue as organic mercury. Organic mercury compounds are more readily absorbed by the oral route than inorganicmercury. In humans, approximately 95% of the ingested organic mercury is absorbedfrom the gastrointestinal tract (11).
Although it is not possible to determine whether adverse health effects would occur at theestimated dose of organic mercury ingested due to lack of health guidelines forcomparison, there was probably limited exposures to the mercury contaminated fish byRV park guests. Therefore, no adverse health effects are expected to occur.
|Contaminant||Exposure Medium||Health Guideline (mg/kg/day)|
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. Thiswould 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 wereidentified 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 surroundingcommunity should become available at a later date, ATSDR will evaluate its significance at thattime.
No community health concerns about the South 8th Street Landfill were expressed by citizens orpublic health officials during the gathering of the information used to prepare this public healthassessment.