PUBLIC HEALTH ASSESSMENT
SANGAMO/TWELVE-MILE CREEK/HARTWELL PCB
PICKENS, PICKENS COUNTY, SOUTH CAROLINA
|% BLACK AND OTHER||31.8||17.8||10.6||6.6|
|% UNDER 10 YEARS||15.1||14.1||13.6||11.8|
|% OVER 65 YEARS||11.1||13.1||12.3||10.5|
|% BELOW POVERTY LEVELb||16.6||12.5||14.0||10.7|
(a) Revised Population Projections for July 1989, for Division of Research and Statistical Services of the South Carolina Budget and Control Board.
(b) From 1980 census of Population, General Social & Economic Characteristics, South Carolina
|SAMPLING POINT||PUBLIC WATER|
|MAX CONC ug/L|
|RAW WATER||EASLEY-CENTRAL # I||0.209||7/8/87||0.005||CREG|
|FINISHED WATER||EASLEY-CENTRAL # I||0.120||5/6/87||0.005||CREG|
|F.H. AT CLARK'S FURN.||EASLEY-CENTRAL # I||0.820 (a)||9/5/90||0.005||CREG|
|SHELL STATION||EASLEY-CENTRAL # I||0.141||5/6/87||0.005||CREG|
|PLEZ-U-STORE||TOWN OF CENTRAL||0.203||8/4/89||0.005||CREG|
|F.H. ON NORTH STREET||EASLEY-CENTRAL # I||3.000 (b)||9/5/90||0.005||CREG|
|F.H. ON 22 MAIN STREET||EASLEY-CENTRAL # I||1.500 (c)||9/5/90||0.005||CREG|
|F.H. AT RIVERSIDE PLANT||EASLEY-CENTRAL # I||1.700 (d)||9/5/90||0.005||CREG|
(a) Pre-flush sample; PCBs were below levels of detection (<0.1) in Post flush Sample.
(b) Post-flush sample; PCBs were <0.1 ug/L in pre-flush sample.
(c) Pre-flush sample; PCBs were detected at a level of 0.75 ppb in post-flush sample.
(d) Post-flush sample; PCBs were detected at a level of 1.1 ppb in pre-flush samples
|SAMPLING POINT||PUBLIC WATER SUPPLY||MAX CONC|
|F.H. AT CENTRAL & HOWE RD.||HWY 88||0.449 (e)||6/5/91||0.005||CREG|
|F.H. AT 122 FABRICA ST.||E. CLEMSON||0.106 (f)||6/5/91||0.005||CREG|
|F.H. AT CLAYTON & WESLEYAN DR.||EASLEY-CENTRAL # I||0.245 (g)||6/5/91||0.005||CREG|
|F.H. AT MOORE & TARRANT ST.||TOWN OF CENTRAL||0.881 (h)||6/5/91||0.005||CREG|
|RESIDENCE A||EASLEY-CENTRAL # I||< 0.100||6/5/91||0.005||CREG|
|RESIDENCE B||EASLEY-CENTRAL # I||0.263||6/5/91||0.005||CREG|
|RESIDENCE C||EAST CLEMSON||< 0.100||6/5/91||0.005||CREG|
|BP STATION||HWY 88||0.101||6/5/91||0.005||CREG|
(e) Pre-flush sample; PCBs were detected at a level of 0.113 ppb in post-flush sample.
(f) Pre flush sample; PCBs were <0.1 ug/L in post-flush sample.
(g) Pre-flush sample; PCBs were unchanged in the post-flush sample.
(h) Pre-flush sample; PCBs were <0.1 ug/L in post-flush sample.
I. PCB Concentrations (as Aroclors) in Drinking Water Samples Collected from Private Residences by SCDHECa
|Easley - Central # I||4||< 0.1 - 0.152b||9/17-11/6/91||0.005||CREG|
|Easley - Central # II||1||< 0.1||9/16/91||0.005||CREG|
|Highway 88||4||< 0.1 - 0.106||9/16 - 11/16/91||0.005||CREG|
|Town of Central||3||< 0.1||9/16-11/6/91||0.005||CREG|
|East Clemson||1||< 0.1||9/16/91||0.005||CREG|
a Level of Laboratory Detection = 0.1 ug/L.
b Sample was split with EPA; EPA detected PCBs at a concentration of 0.16 ug/L.
| PCB CONCENTRATIONS|
|Easley - Central # I||6d||0.048 - 0.294||9/17/91||0.005||CREG|
|Easley - Central # II||2||< 0.05||9/17/91||0.005||CREG|
|Highway 88||3||0.052 - 0.084||9/17/91||0.005||CREG|
|Town of Central||4||0.06 - 0.22||9/17/91||0.005||CREG|
|East Clemson||3||0.052 - 0.06||9/17/91||0.005||CREG|
c. Level of Laboratory Detection = 0.05 - 0.2 ug/L.
d. One sample was split with SCDHEC; SCDHEC detected PCBs at a concentration of 0.152 ug/L.
Sediment samples in mg/kg (ppm)
|1986||64.30||0.05||< 0.01||< 0.01||0.58||2.21||< 0.01||1.20||0.09||CREG|
(a) Sampling Station located in Twelve Mile Creek.
(b) Sampling Station located in Eighteen Mile Creek.
(c) Sampling Station located in Lake Hartwell at Andersonville Island.
(d) Sampling Station located in Tugaloo River.
(e) Sampling Station located in Lake Hartwell in vicinity of the Lake Hartwell Dam.
I. Dibenzodioxin and Dibenzofuran Congeners (2)
|2,3,7,8 TCDF (DIBENZOFURAN)||0.004800||8/6/85||700||EMEG|
(1) All data have been converted into TCDD Equivalents using the International Toxicity Equivalent factors, 1988.
(2) Concentrations for dibenzodioxins & dibenzofurans are expressed in ng/kg (ppt).
(mg/kg or ppm)
SPECIES: WHITE / CHANNEL CATFISH (2) PCB Fish Tissue concentration (mg/kg)
(1) Fish Samples from 1977-1981 were fillet composites from 5 fish. Fish samples from 1983-1985 were both fillets of individual fish (n 3-10 fish/station) and fillet composites from 5 fish. Samples from 1986-1089 were individual whole fish (~4-10 fish/station) that were only eviscerated and deheaded; catfish were also skinned, all others were not.
(2) Weight ranges, catfish composites: 0.6-0.9 lbs (1977-1981), 0.78-5.13 lbs (1983-1985); Weight range, individual fish: 0.75-5.24 lbs (1983-1985), 1.8-3.7 lbs (1986), 2.7-3.2 lbs (1989).
(3) Weight range, Largemouth composites: 0.6-2 lbs (1977-1981), 0.96-4.9 lbs (1983-1985); Weight range, individual fish: 0.75-5.24 lbs (1983-1985, 1.8-3.7 lbs (1986), 2.7-3.2 lbs (1989).
(4) Weight range, White /Hybrid composites: 1-2.3 lbs (1977-1981), 0.91-4.13 lbs (1983-1985); Weight range, individual fish: 2.07-4.88 lbs (1983-1985), 3.1-4.8 lbs (1986), 3.1-4.6 lbs (1989).
(5) Weight range, Black Crappie, individual fish: 0.4-2.01 lbs (1986) 0.44-0.99 lbs (1989).
|LOCATION||STATION||TYPE FISH|| TOTAL|
|18 MI CREEK||12.1||HYBRID||<20||4.6||<0.02||4.6||0.56||1.6||2.11|
|18 MI CREEK||12.2||HYBRID||<10||3.4||<O.01||3.4||0.4||1.4||1.8|
|18 MI CREEK||12.3||HYBRID||<20||9.9||<O.01||9.9||1.8||3.2||5|
|12 MI CREEK||12.4||HYBRID||<10||29||<0.01||29||46||51||97|
|12 MI CREEK||12.5||CATFISH||<10||<1.0||<0.01||<10||4.1||23||27.1|
|12 MI CREEK||12.6||CATFISH||<10||<1.0||<0.01||<10||2.2||1.6||3.8|
|12 MI CREEK||12.7|| LARGE|
|12 MI CREEK||12.8|| LARGE|
|12 MI CREEK||12.9|| LARGE|
|12 MI CREEK||12.10|| LARGE|
|12 MI CREEK||12.11|| LARGE|
|12 MI CREEK||12.12|| LARGE|
|12 MI CREEK||12.13||CATFISH||<10||<1.0||<0.01||<10||4.2||11||15.2|
|12 MI CREEK||12.14||CATFISH||<20||<1.0||<0.01||<20||18||50||68|
|12 MI CREEK||12.15||NOT LISTED||<10||<1.0||<0.01||<10||1.8||4.4||6.2|
|LAKE HARTWELL||HD-1||FISH COMP.||<10||22||15.5||37.5||37||110||147|
|TUGALOO RIVER||COMP 1|| HYBRID|
|TUGALOO RIVER||COMP 2|| HYBRID|
|TUGALOO RIVER||COMP 5|| HYBRID|
|C 23|| HYBRID|
All PCDD/PCDF data are converted into TCDD equivalents using the International Equivalent Factors/'88.
Concentrations are expresses in ng/kg or ppt.
Laboratory level of detection < 10 ppt.
Concentrations of PCBs are expressed in mg/kg or ppm.
SCDHEC's FISH MONITORING PROGRAM FOR TWELVE MILE CREEK/LAKE
The following text discusses the various factors and methodological issues that have had a direct effect on the data generated by this program.
Every April, from 1977 to 1985, SCDHEC collected 2-to-3 year old largemouthbass, white catfish, and white/hybrid bass from stations in Twelve Mile Creek(SV-107), in Eighteen Mile Creek (SV-532) and at Andersonville and (SV-535)(See Figure 3). SCDHEC selected these fish species for study because oftheir association with sport and/or commercial fisheries and because of theirvarying migratory patterns and habitat selections. SCDHEC later added BlackCrappie to the monitoring program when it was found to be an important LakeHartwell gamefish.
Largemouth bass are widely distributed predators and sport species thatundergo seasonal movements from shallow to deep water and have open-waterschooling tendencies in late summer and fall. SCDHEC staff do not believethat the largemouth bass have been moving significantly outside their homeranges. As well as being a highly sought gamefish, the hybrid bass are amigratory fish that have the potential to move in and out of the contaminatedareas of Lake Hartwell. They are generally schooling open-water fish with atendency to concentrate in tributary arms and streams during spawningperiods. As a result, the data from samples of Hybrid bass have been markedby much variability. White catfish are bottom-dwelling omnivores of sportand commercial value.
In 1986, the sampling program was modified to include 2 additional samplingstations: SV-641 (in the Tugaloo River) and SV-642 (in vicinity of LakeHartwell Dam). The Tugaloo River is the other riverine embayment of the lakethat was not subject to direct input of PCBs.
1. Sampling Periods 1977-1981:
For the sampling years 1977-1981, only fish fillets (that is, the edibletissue) were analyzed for PCBs. Samples were usually composites of 5,similarly-sized fish of the same species; however, composites occasionallyranged from 2-7 fish, depending on availability. Composite samples were usedto reduce the cost of tissue analyses (SCDHEC, 1982).
The study protocol during these years occasionally had to be modified whentarget species were not available at sampling stations; substitutions withother more abundant species were made although the size ranges had to beadjusted. White bass and hybrid bass were included in the same group. Although white bass were the initial target species, hybrids were alsoinadvertently collected since their similar body features made them difficultto tell apart. During some collections, white bass were unavailable and weresubstituted with the hybrids. However, since they are considered to begenetically related and have similar feeding and migratory habits, theirbioaccumulation rates were assumed to be the same (SCDHEC, 1982).
Twelve Mile Creek (SV-107): Fish in Twelve Mile Creek tend to have thehighest PCB concentrations. Between the years 1977-1981, there has been astatistically significant downward trend in the PCBs concentration of whitecatfish. No downward trend was found for the largemouth and white/hybridbass except for 1 year, between 1980-1981, for white/hybrid samples.
Eighteen Mile Creek (SV-532): As was noted in SV-107, there has been asignificant downward trend in the PCB concentration of white catfish;however, it did not occur to the same degree. This difference was notedparticularly between 1977 and 1980. There was also a significant differencein tissue concentrations between the years 1980 and 1981. There was nosignificant trend noted in the data for white/hybrid and largemouth bass.
Andersonville Island (SV-535): A downward trend was noted in the PCBconcentrations of white/hybrid bass. However, this difference was only foundto be significant when data from 1977 was compared to the data from theremaining years. Data from years 1978 to 1981 showed no significantdifference and no apparent downward trend since 1978. Data on white catfishand largemouth bass show only moderate declines over the sampling years(SCDHEC, 1982).
2. Sampling Periods 1983-1985:
During these years, hybrid bass, largemouth bass, and channel/white catfishwere collected from Twelve Mile Creek, Eighteen Mile Creek and from theMartin Creek area (SV-106), approximately halfway between these stations. Nosamples were collected at the Andersonville Island station. All 3 specieswere not collected at each sampling station. Both individual fish andcomposite samples of 5 fish of a similar weight class were assayed for PCBs. From the sampling results, it appears that there was a sizeable increase inthe PCB concentrations of catfish and largemouth bass taken from Twelve MileCreek. There was no appreciable decline in the PCB concentrations in catfishtaken from Martin Creek although there was a significant decline in the PCBconcentrations in largemouth and hybrid bass from this Creek. Based on theseresults, SCDHEC and EPA reaffirmed the fishing advisory.
3. Sampling Period 1986:
The SCDHEC sampling protocol was substantially modified in 1986. Besidesadding 2 sampling stations and a fourth fish species to the monitoringprogram, the method of preparing fish samples for analyses was markedlychanged.
Black crappie, largemouth bass and hybrid bass were selected for the 1986study because they are important Lake Hartwell gamefish. According to the1982 SCWMRD creel survey, they represented nearly 40, 24, and 23 percent,respectively, of the public harvest in Lake Hartwell (catfish representedonly 1.76% of the public harvest). Thus, they could be used to develop areasonable, worst-case scenario for dose estimates. This creel survey didnot gather data on sampling location; thus, we do not know whether the surveyrespondents represented bank fishermen or fishermen using boats.
Reviewing past sampling data from SV-107, SCDHEC staff noted much variabilityin the PCBs levels among fish of the same weight class and species. Toreduce this variability and to allow for more accurate trend analyses,individual fish were de-headed and eviscerated; no areas of fatty tissue weretrimmed except from the body cavity. This technique is referred to as amodified whole fish preparation. This method contrasts with the filletpreparation (the edible portion of the fish trimmed of all fatty tissues)which was used prior to 1986. Except for catfish, all the fish were analyzedwith the skin on. SCDHEC staff used the modified whole fish preparation asa means of limiting the variability in data believed to have resulted becauseof individual filleting techniques. They also believed some people may bepreparing fish in a similar manner.
Despite this change in technique, they found the same level of variability inthe data. SCDHEC staff now believe that this can primarily be attributed tothe variability in the lipid content in fish of the same weight class andspecies. Other contributing factors may be the variability in thecontaminant levels of Twelve Mile Creek sediments and the migratory andfeeding patterns of each fish species.
Until this point in time, PCB levels in Twelve Mile Creek fish had fluctuatedwidely while PCB levels in fish from other locations had remained fairlyconstant. When the 1986 data is compared to the data from prior years, itappears that the fish are becoming more contaminated. SCDHEC staff mainlyattribute this perceived increase to the change in sample preparation becausethey believe the lipid content of modified whole fish samples is greater thanthat of fillet samples. Since PCBs selectively accumulate in fat tissues,the samples' PCB concentrations should also be greater. They could notconclusively state this since they did not have the resources to analyzesimilarly-sized samples by both methods. However, the modified samplingmethod is not the only possible cause for the increased PCB levels in thesefish. First, these fish had similar levels in 1985 before the samplingprocedure was changed. Second, the PCB concentrations in the sediments ofTwelve Mile Creek collected in 1985 and 1986 were found to be much greaterthan the sediment data from previous years. Thus, the PCB concentrations inthese fish more likely reflect the higher PCB concentrations in thesesediments. The cause of the increase in these sediments is not known.
White/channel catfish tended to have higher concentrations of PCBs; they arebottom feeders and can ingest PCBs in sediments. For analysis, white andchannel catfish were grouped in 1 category. This was done for 2 reasons: ithad been done in earlier sampling rounds and there was some difficultycollecting sufficient numbers of either species at all sampling stations. The channel catfish were readily collected at the riverine stations while thewhite catfish were readily collected at the open-water stations. The datawere still able to be used for trend monitoring since the ratio of eachspecies of catfish was similar between stations and it was believed that bothspecies were equally consumed by the public (the 1982 creel survey did notspeciate the catfish).
All fish collected from the Seneca River arm of the lake, north of the SCHighway 24 advisory boundary, had mean PCBs values above the current FDAlimit. At the remaining 3 stations, only hybrid bass and catfish had meanPCBs levels greater than this level.
4. Sampling periods 1987-1988:
There are no data available for review. SCDHEC contracted with a privatelaboratory to analyze fish samples collected during these years. However,the sampling results from this laboratory were found to be considerably outof line with prior sampling data. SCDHEC laboratory staff subsequently foundserious problems with this laboratory's quality assurance/quality controlpractices and procedures. Thus, SCDHEC rejected the data.
5. Sampling period 1989:
A total of 74 fish were collected by SCDHEC from stations in Twelve MileCreek, Eighteen Mile Creek, Tugaloo River and at Andersonville Island. Largemouth bass, black crappie, hybrid bass and 4 channel catfish of similarweight classes were collected at the Eighteen Mile Creek Station. Financialconstraints prevented them from collecting all 4 species at the otherstations. All fish were prepared for PCB analyses using the modified wholefish technique. All catfish were skinned; the other 3 species were analyzedwith the skin on.
As seen in the data from 1986, fish within the advisory exceeded FDA's limit. There was a noticeable decrease in the PCB concentrations of the largemouthbass from Twelve Mile Creek between the years 1986 and 1989 (data from 1987and 1988 was deleted as mentioned above). A less pronounced decrease wasnoted in the largemouth bass samples taken from the Eighteen Mile Creek. There was an increase in the PCB concentrations in fish samples collectednear Andersonville Island.
There was an increase in the PCB concentrations of the hybrid samples takenfrom Eighteen Mile Creek; there was also a similar increase in theconcentrations of the fish collected from the Tugaloo River. Not only didthese fish exceed the FDA limit, but they were collected outside of theadvisory area. Yet, the PCB concentrations in hybrid samples taken fromTwelve Mile Creek had decreased. Samples of black crappie and channelcatfish caught in Eighteen Mile Creek also seemed to have increased in PCBconcentrations when compared to the sampling results of 1986. Additionalsampling results for later years is needed to further evaluate this trend.
6. Sampling period 1990-1991:
No sampling data from these years were available for review. The SCDHEClaboratory is completing analysis of the 1990 fish data. Fish collectedduring 1991 will be analyzed by a contract laboratory funded by the federalSuperfund Program.
Response to Comments received during the Public Comment Period
The following responses address technical comments submitted by the publicduring the public comment period of September 21, 1992 to October 23, 1992. Comments received about the report's format, site hazard ranking, and theneed for a site visit will not be addressed as they were prepared inaccordance with ATSDR's Public Health Guidance Manual, March, 1992.
1. Concerns were raised about the assumptions chosen for the exposurescenario for subsistence fishermen. One reviewer considered the assumptionsto be overly conservative while another reviewer believed that fishermen werenot following the advisory and were collecting fish from areas covered by theadvisory. These uncertainties were discussed under 2 headings in the PublicHealth Implications Section: 1. Polychlorinated biphenyls: a. Food Chain: Fish (Page 22) and 3. Uncertainty (Page 28). The reviewers are encouragedto review these discussions for further clarification.
The risk to the fish-consuming public is best characterized if actualexposure data were available. Since these data did not exist, assumptionswere made to estimate the exposure. While the range of assumptions that canbe used is broad, the assumptions that are typically chosen account forindividuals with the greatest exposures (in this case, subsistencefishermen). This also accounts for risks to the more sensitive members ofthe population (that is, children, the elderly, the debilitated and thechronically ill). One reviewer considered the use of the maximally exposedindividual (MEI) for estimating risk to the fish-consuming public to beoverly conservative. In the scenario presented in the Public HealthAssessment, the MEI was not actually considered; for this assumption to bemade, we would have to assume that subsistence fishermen are consumingmaximally-contaminated fish from the area under that advisory. (Contrary tothe opinion of this same reviewer, there have been anecdotal reports thatfishermen are collecting fish from Twelve Mile Creek, in areas covered by theadvisory). The exposure scenario that seemed more plausible was to considersubsistence fishermen who are following the advisory. If the risk fromexposure fell within an acceptable range as defined in the NationalContingency Plan, then we would have considered an MEI exposure scenario. Wedid not need to go further since we did not find this to be the case.
A question was raised about the choice of the consumption rate for localfishermen. Again, without data on local consumption patterns, we could onlyrely on an assumption. In this case, we chose the annual consumption rate(90th percentile) for recreational fishermen from the U.S. west coast. Thisvalue is cited in EPA's, Exposure Factor Handbook, July, 1989. It isrecommended that these values be used to represent consumption rates forrecreational fishermen in any area where a large water body is present andwidespread contamination is evident. The 90th percentile rate was chosenbecause we believed subsistence fishermen could be consuming fish at thatrate. We also assumed that the individual's fish diet consisted solely ofLake Hartwell fish. We certainly agree that the risk of exposure is directlyrelated to the amount of contaminated fish consumed per day. Thus, a lowerconsumption rate would result in a lower estimate of risk. However, withoutsite-specific consumption data from surveys of local fishermen, anotherconsumption rate would merely be arbitrarily selected. Certainly, these riskestimates will be revised when the SCWMRD completes their survey of theactual consumption patterns of Lake Hartwell fishermen.
2. A concern was raised about the assumption that "the effects from Aroclor1260 is assumed to be representative of all PCB mixtures;" this assumptionwas used in calculating cancer risk. The objection to the use of thisassumption was that it was an "outdated premise." Several attachments werealso provided for reference.
We are well aware of the recent efforts to revisit the cancer potency ofPCBs; it follows on the heels of EPA's reassessment of dioxins. However, inthe case of dioxins, the EPA has withdrawn its cancer potency factor fromtheir Integrated Resource Information System (IRIS) database until they canfinalize their opinion.
Such is not the case, however, for PCBs. The cancer potency factor for PCBswas calculated from data generated by a study of laboratory rats fed Aroclor1260. In developing this cancer potency factor, the EPA assumed that Aroclor1260 was representative of all mixtures and that the potency estimate forAroclor 1260 applies to all PCB mixtures (ATSDR Tox. Profile for SelectedPCBs (Aroclor-1260, -1254, -1248, -1242, -1232, -1221, and -1016). Thisopinion has not yet changed, nor has the EPA begun efforts to reassess PCBtoxicity.
We agree that the relative toxicities of PCBs mixtures may vary because oftheir varying levels of chlorination. However, there is of yet insufficientdata to adequately characterize these differences. We agree with the commentthat risk calculations should be congener specific; however, the EPA has notyet adopted a weighted approach similar to the toxicity equivalent factorapproach it developed for dealing with dioxin congeners (this has beenreferenced in the Public Health Assessment). We are aware that equivalencyfactors for polyaromatic hydrocarbon compounds (PAHs) and for PCBs can befound. However, the EPA has not yet recognized their validity and has notrecommended their use. There is no indication that this will occur in thenear future.
3. There was a concern raised about the use of present available data tomake assumptions about cancer risk to consumers of municipal drinking water. The main objection was to the characterization of cancer risk for PCB levelsin drinking water that were "nondetectable or below health based standards." Certainly, as sampling has shown, the PCB levels in drinking water havefluctuated widely from tap to tap and at each individual tap. Thus, assuminga PCB level will remain the same for a lifetime (or 70 years) becomes highlyunlikely and adds to the level of conservancy in the risk estimate. However,in the scenario presented, the maximum concentration level from a private tapwas chosen to estimate the maximum risk to consumers. Given the erratic andunpredictable nature of the sampling data, this choice was a reasonableapproach. Additional sampling results will better characterize concentrationlevels at private taps and help to reduce the level of uncertainty in therisk estimate. Even though these water supplies will continue to bemonitored, exact characterization of contaminant concentrations will be quitedifficult and costly.
We are aware that some sample results were below detectable levels; however,for the samples where PCBs were identified, there are no "health basedstandards" which could be used for comparison. The EPA has developed an MCLfor PCBs as decachlorobiphenyls in drinking water; however, this standardcannot be compared to the data results because they are reported as Aroclors. There is no acceptable methodology yet to measure PCB concentrations asdecachlorobiphenyls nor is there an approved method to express Aroclorsrelative to the toxicity of decachlorobiphenyls. In addition, the MCL is notnecessarily a health-based standard; it is a legally enforceable standardthat takes into account available analytical methods of detection and watertreatment capabilities as well as the cost of achieving various contrationlevels of contaminants. We do not know what other "standard" the reviewer isciting.
4. There was a concern that contamination of surface soils along theshoreline should not be considered as a possible health threat as it"represents an unsubstantiated conclusion." We concur with the reviewer thatrisk of exposure is indeed unsubstantiated and will remain so unlessadditional surface soil samples are collected from locations frequented bythe public. We realize that studies have addressed the sediment of the creekbottoms. However, we did not find any sampling results from the accessibleshorelines where people can readily fish, wade, and swim. Additional samplesfrom these locations will help us determine if this pathway is a complete oneor if it can be eliminated.
5. There was a concern raised about the accuracy of the TRI data. For thePublic Health Assessment, we simply cite the available TRI data; we do notcritically review it for accuracy. The TRI database depends on self-reporting by each industry. It has been found to have numerous errors in thepast and will continue to do so unless there is some effort to validate thedata that is submitted. Presently, such a review process is not arequirement of TRI nor are there plans to do so in the future.
6. The comment about the presence of Aroclor 1260 (not used by Sangamo) insome drinking water sampling results suggests the possibility of othercontaminant sources. The possibility that PCBs could be emanating insignificant amounts from abandoned electrical transformers and capacitorsthat remained in areas that were flooded by the U.S. Army Corps of Engineersseems quite unlikely. Firstly, the predominant congener found hashistorically been Aroclor 1242, with Aroclors 1254 and 1016 found in lesseramounts. The incidental finding of Aroclor 1260 in several drinking watersamples may point to contribution from an additional source but it is dwarfedin importance by the contribution of PCBs from Sangamo. Secondly, since1976, Sangamo has been considered to be the source of PCB contamination infish, sediments, and drinking water. Information about any other actualsources of PCB contamination to this Lake system should be brought to theattention of the EPA project manager for this site.
7. One reviewer raised issue about the inclusion of the words "Twelve MileCreek/Lake Hartwell watershed" into the OU-2 designation used by EPA. Theyconsidered it misleading to consider this situation a watershed problem. Weconcur with the reviewer that the situation should not include the watershedbut involves PCB contamination of the sediments and fish of this Lake Systemas well as the municipal drinking water systems that receive raw water fromit. We feel that this has been explained in detail in the Public HealthAssessment. Since the EPA has artificially separated this site into 2operable units and officially used the term "watershed" in its description ofthe OU-2 site, its use in the Public Health Assessment was merely forbackground information. For further clarification, I would refer thereviewer to the May, 1991 Superfund Fact Sheet for this site.