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PUBLIC HEALTH ASSESSMENT

FRONTERA CREEK
RIO ABAJO, HUMACAO COUNTY, PUERTO RICO


APPENDICES

Appendix A - Environmental Contamination Data
Appendix B - Pathways Analyses
Appendix C - Comparison of Estimated Exposure Doses to Health Guidelines
Appendix D - Blood Mercury Data
Appendix E - Summary of Previous Environmental Sampling
Appendix F - Figures 1 & 2
Appendix G - Public Comments

Appendix A - Environmental Contaminant Data

Explanation of Environmental Contamination Data Tables
Explanation of Comparison Values
Table 1 - On-site Surface Soil
Table 2 - On-site Sediment
Table 3 - On-site Surface Water
Table 4 - On-site Air
Table 5 - Off-site Soil: Ciudad Cristiana Surface Soil
Table 6 - Off-site Soil: Ciudad Cristiana Subsurface Soil
Table 7 - Off-site Air

Explanation of Environmental Contaminant Data Tables

In the data tables that follow, the listed contaminant does not mean that it will cause adversehealth effects from exposures. Instead, the list indicates which contaminants will be furtherevaluated in the public health assessment.

The data tables include the following abbreviations:
  • CREG
  • = Cancer Risk Evaluation Guide
  • EMEG
  • = Environmental Media Evaluation Guide
  • RMEG
  • = Reference Dose Media Evaluation Guide
  • ppm
  • = parts per million
  • mg/kg/day
  • = milligrams per kilogram per day
  • µg/m3
  • = micrograms per cubic meter of air
  • Rfd
  • = Reference Dose
  • MRL
  • = minimal risk level
  • IEMEG
  • = Intermediate Environmental Media Evaluation Guide
  • ND
  • = not detected
  • MDL
  • = method detection limit
  • BMDL
  • = below method detection limit
  • FREQ>DL
  • = the number of times a concentration exceed the method detection limitcompared to the number of times it was analyzed
  • FREQ>CV
  • = the number of times a concentration exceeded the comparison valuecompared to the number of times it was analyzed.

    Sources of Data - (4,17,18,37)

    Explanation of Comparison Values

    Environmental media evaluation guides (EMEGs) are based on ATSDR's minimal risk levels(MRLs) and are the estimated contaminant concentrations in water or soil at which there is verylittle or no chance of noncarcinogenic health effects occurring (2). Reference dose mediaevaluation guides (RMEGs) are the same as EMEGs, except that they are based on EPA'sreference dose (Rfd) rather than MRLs. Exceeding the EMEGs and RMEGs does not mean thathealth effects will occur, just that further evaluation is needed.

    EMEGs and RMEGs for soil are calculated using soil ingestion rates of 100 micrograms/day(µg/d) for adults, 200 µg/d for children, and 5000 µg/d for pica (the habit of eating soil) /children(2). EMEGs and RMEGs for water are computed using 2 liters/day for adults and 1 liters/day forchildren. For both water and soil calculations, a bodyweight of 70 kilograms is assumed foradults and 10 kilograms for children. For air, the MRL for air is used as the air EMEG.

    Cancer risk evaluation guides (CREGs) are the estimated contaminant concentrations in water,soil, or air based on a one excess cancer in a million persons exposed over a lifetime (38). CREGs are calculated from EPA's cancer slope factors.

    An ATSDR minimal risk level (MRL) is the estimated daily human exposure to a chemical forwhich there is no appreciable risk of adverse noncarcinogenic effects (2). There can be MRLsfor acute/short-term (less than 15 days), intermediate (15 days - 1 year), or chronic/long-term(more than 1 year). MRLs are based on the no effect or lowest effect levels observed in humanexposures or animal studies. This no or lowest effect level is adjusted by a factor of 10 to 1,000depending on strength of study, whether the data were animal or human, or several other factorsto derive the MRL.

    EPA's Reference Dose (RfD) and Reference Concentration (RfC) are similar to the MRL. A RfDis for ingestion and a RfC is for inhalation (39).

    Table 1.

    ON-SITE SURFACE SOIL (0-6 inches in depth)1
    CONTAMINANT FREQ >DLCONCENTRATION
    RANGE
    in ppm
    COMPARISONVALUE2 (CV)FORINGESTION FREQ>CV
    ppmSource
    mercury (total)67/1220 - 535200RMEG31/122
    mercury(inorganic)19/330 - 71000IEMEG40/33
    arsenic9/52ND - 4300.4CREG9/52
    beryllium1/390 - 0.350.2CREG1/39
    1 - See the Environmental Contamination and Other Hazards section for adescription of where the samples were collected. These data were all collected in1988. See Appendix E for a review of earlier sampling.

    2 - These comparison values were calculated for adults because exposure tochildren was considered extremely unlikely due to the restricted access to theindustrial facilities. See the Environmental Contamination Section for additionalinformation and explanation.

    3 - The RMEG for methyl mercury was used as the comparison value for totalmercury. See the Toxicological Evaluation section for a discussion of theimplications of the use of this value.

    4 - IEMEG is the intermediate environmental media evaluation guide for inorganicmercury.

    5 - The concentration range is within background for soils in the Humacao area.

    Table 2.

    TABLE 2 - ON-SITE SEDIMENT1
    CONTAMINANTCONCENTRATION
    RANGE
    in ppm
    COMPARISONVALUE (CV) FORINGESTION* FREQ>CV
    ppmSource
    arsenicBMDL - 100.4CREG11/13
    beryllium0.3 - 0.470.2CREG5/5
    1 - These data were all collected in 1988. See Appendix E for a review of earliersampling.

    * The comparison values used here are for soil, because none are available forsediment.



    Table 3.

    ON-SITE SURFACE WATER1
    CONTAMINANTCONCENTRATION
    RANGE
    in ppm
    COMPARISONVALUE (CV) FORINGESTIONFREQ>CV
    ppmSource
    methyl isobutyl ketone0 - 4.7noneNA2
    methylene chloride0 - 1.90.005CREG2/2
    1 - Samples were collected from Technicon Ditch and from Frontera Creek adjacent toSquibb. These data were all collected in 1988. See Appendix E for a review of earliersampling.

    2 - Only 2 of 7 samples were above the method detection limit.



    TABLE 4 - ON-SITE AIR1
    CONTAMINANTCONCENTRATION
    RANGE in µg/m3
    COMPARISON VALUE (CV) FORINHALATION
    Concentration in µg/m3Source
    mercury0.03 - 2.20.06ChronicEMEG/MRL2
    acetoneND - 618950AcuteEMEG/MRL
    methylene chloride(1989)627 - 19562CREG3
    methylene chloride(1992)46 - 64242CREG3
    methylene chloride
    (1993-1994)
    5.3 - 81242CREG3
    1 - See the Environmental Contamination and Other Hazards (ECOH) section for adescription of where and how the samples were collected. These data were allcollected in 1989, except for methylene chloride samples collected in 1992 and1993-1994. See Appendix E for a review of earlier sampling.

    2 - The chronic EMEG/MRL for metallic mercury was used. There are no comparisonvalues for organic or inorganic mercury; however, the sampling methodology detectedonly metallic mercury.

    3 - For methylene chloride, the intermediate EMEG/MRL is 105 µg/m3 and the acuteEMEG/MRL is 1390 µg/m3. The CREG is used here to select this chemical for furtherevaluation. The EMEG/MRLs will be discussed further in the ToxicologicalEvaluation section.

    4 - These levels are 24-hour averages. See ECOH for details on day, evening, andnight averages.



    TABLE 5 - OFF-SITE SOIL: CIUDAD CRISTIANA SURFACESAMPLES (0 - 3 inches)1
    CONTAMINANTFREQ>DLCONCENTRATION
    RANGE inppm
    COMPARISONVALUE (CV)FOR INGESTION2 FREQ>CV
    ppmSource
    mercury (total)91/164ND - 0.8360.63RMEG 1/164
    mercury(inorganic)23/67ND - 0.7174IEMEG0/67
    arsenic20/32BMDL - 4.140.4CREG32/325
    barium32/3247 - 4054100RMEG31/32
    manganese32/32434-1,980610RMEG32/32
    beryllium32/320.1 - 0.2860.2CREG20/32
    1 - See the Environmental Contamination and Other Hazards section for adescription of where the samples were collected. These data were all collected in1988. See Appendix E for a review of earlier sampling.

    2 - These values were calculated for pica children.

    3 - The RMEG for methyl mercury was used as the comparison value for totalmercury. See the Toxicological Evaluation section for a discussion of theimplications of the use of this value.

    4 - The concentration range is within background for soils in the United States asdescribed on Table 4-15 of the RI (4).

    5 - The method detection limit for arsenic was 2 ppm. However, quantificationwas possible below the method detection limit so results were compared to thecomparison value for mercury.

    6 - The concentration range is within background for soils in the Humacao area.

    Table 6.

    OFF-SITE SOIL: CIUDAD CRISTIANA SUBSURFACE SOIL1
    CONTAMINANTFREQ>DLCONCENTRATION RANGE in ppmCOMPARISONVALUE (CV) FOR INGESTION2FREQ>CV
    ppmSource
    mercury (total)6/79ND - 0.2360.63RMEG0/79
    mercury(inorganic)2/79ND - 0.1824IEMEG0/10
    barium10/1074.1 - 402100RMEG3/10
    manganese10/1074.7 - 2,41010RMEG4/10
    beryllium9/10ND - 0.400.2CREG6/10
    1 - See the Environmental Contamination and Other Hazards section for adescription of where the samples were collected. These data were all collected in1988. See Appendix E for a review of earlier sampling.

    2 - These values were calculated for pica children.

    3 - The RMEG for methyl mercury was used as the comparison value for totalmercury. See the Toxicological Evaluation section for a discussion of theimplications of the use of this value.



    Table 7.

    OFF-SITE AIR1
    CONTAMINANTCONCENTRATION
    RANGE in µg/m3
    COMPARISON VALUE (CV) FORINHALATION
    ConcentrationSource
    mercury0.043 - 0.08730.06ChronicEMEG/MRL2
    acetoneND - 16.4950AcuteEMEG/MRL
    methylene chloride(1989)30.4 - 55.12CREG3
    methylene chloride(1992)124,52CREG3
    methylene chloride

    (1993-1994)

    5.6 - 2942CREG3
    1 - See the Environmental Contamination and Other Hazards (ECOH) section for adescription of where and how the samples were collected. These data were allcollected in 1989, except for the methylene chloride samples collected in 1992 and1993-1994. See Appendix E for a review of earlier sampling.

    2 - The chronic EMEG/MRL for metallic mercury was used. There are no comparisonvalues for organic or inorganic mercury; however, the sampling methodology detectedonly metallic mercury.

    3 - For methylene chloride, the intermediate EMEG/MRL is 105 µg/m3 and the acuteEMEG/MRL is 1390 µg/m3. The CREG is used here to select this chemical for furtherevaluation. The EMEG/MRLs will be discussed further in the ToxicologicalEvaluation section.

    4 - These are 24-hour averages. See ECOH for details on day, evening, and nightaverages.

    5 - Only one off-site location was sampled in 1992.

    Appendix B - Pathways Analyses

    Table 8 - Completed Exposure Pathways
    Table 9 - Potential Exposure Pathways
    Table 10 - Estimated Population for Completed and Potential Exposure Pathways

    Table 8.

    COMPLETED EXPOSURE PATHWAYS
    PATHWAYNAME ANDCONTAMINANT OFCONCERNEXPOSURE PATHWAY ELEMENTS
    SOURCEENVIRONMENTAL MEDIAPOINT(S) OFEXPOSUREROUTE OFEXPOSUREEXPOSEDPOPULATIONTIME
    TechniconSurface Soil
    (mercury)
    TechniconFacilitySurface Soilareas ofTechniconfacility withmercury-contaminated soilingestion ofor skincontact withmercury-contaminated soil anyone whocontactedmercury-contaminated soils atTechniconpast
    Industrial SurfaceSoil
    (arsenic)
    Natural -except for 2locationsSurface Soilareas of the sixfacilities witharsenic-contaminated soilingestion ofor skincontact witharsenic-contaminated soilanyone whocontactedarsenic-contaminated soils at thesix facilitiespast, present,future
    Owens-Illinois Soil
    (beryllium)
    NaturalSurface Soilone location attheOwens-Illinoisfacilityingestion ofor skincontact withberyllium-contaminatedsoilanyone whocontactedberyllium-contaminated soils atthis one locationpast, present,future
    Ciudad Cristiana Soil
    (arsenic, barium,beryllium,manganese, andmercury)
    NaturalSurface Soilfor arsenic,barium,beryllium, &manganese anypart of CiudadCristiana; formercury onepart of one yardingestion ofor skincontact withcontaminated-soilanyone whocontactedcontaminatedsoils at CiudadCristianapast
    Ambient Air
    (methylenechloride, acetone,and mercury)
    Squibb formethylenechlorideandacetone;mercurysourceunknownAirFrontera Creekarea industrialfacilities andresidencesdownwind fromSquibbinhalation ofcontaminatedairworkers andresidents inFrontera Creekareapast, present,future (forCiudadCristianaresidents pastexposure only)
    Surface Water
    (methylenechloride, andmethyl isobutylketone)
    FronteraCreekIndustrialFacilitiesSurface Waterthat portion ofFrontera Creek that runsthroughindustrial areaingestion ofor skincontact withcontaminatedsurface wateranyonecontactingsurface water atpoints ofexposurePast


    Table 9.

    POTENTIAL EXPOSURE PATHWAYS
    PATHWAYNAMEEXPOSURE PATHWAY ELEMENTSTIME
    SOURCEENVIRONMENTAL MEDIAPOINTSOFEXPOSUREROUTESOFEXPOSUREEXPOSEDPOPULATION
    SedimentFrontera CreekIndustrialFacilitiesSedimentthat portionof FronteraCreek thatruns throughindustrialareaingestion ofor skincontact withcontaminatedsedimentanyonecontactingsediment atpoints ofexposurePast


    Table 10.

    ESTIMATED POPULATION FOR COMPLETED AND POTENTIAL EXPOSURE PATHWAYS*
    EXPOSED POPULATIONS ANDPOTENTIALLY EXPOSEDPOPULATIONS AFFECTED BY A COMPLETED OR POTENTIAL EXPOSURE PATHWAY* FOR:
    Population and LocationApprox# ofPersons

    arsenic
    bariumberylliummanganese

    mercury
    methylene
    chloride
    Workers at Techniconunknown



    SSoil
    Air
    SW
    Air
    Workers at Frontera CreekIndustrial FacilitiesunknownSsoil
    Sediment

    Sediment
    Soil


    Air
    SW
    Ciudad Cristiana Residentsless than10 formercury;1000 forotherfourmetalsSSoilSSoilSSoilSSoilSSoil at onelocationAir
    Other Residents ofFrontera Creek AreaUnknown




    Air

    *potential exposure pathways are redlined
    SW - surface water
    SSoil - Surface Soil
    1 - See the Pathways Analyses section for a discussion of mercury in the surface soil at CiudadCristiana. Exposure to mercury at Ciudad Cristiana was not site-related.

    Appendix C - Comparison of Estimated Exposure Doses to Health Guidelines

    Table 11 - Comparison of Estimated Exposure Dose to Health Guidelines for Ingestion
    Table 12 - Comparison of Estimated Exposure Dose to Health Guidelines for Inhalation
                      Calculation of Exposure Doses for Soil Ingestion
                      Calculation of Risk of Carcinogenic Effects


    Table 11.

    COMPARISON OF ESTIMATED EXPOSURE DOSE TO HEALTH GUIDELINES FOR INGESTION1
    CONTAMINANTEXPOSUREPATHWAYHEALTHGUIDELINE INMG/KG/DAYSOURCEHEALTH GUIDELINEEXCEEDED BYEXPOSURE DOSE
    arsenicIndustrial FacilitySurface Soil0.0003RfD2YES
    arsenicCiudad CristianaSurface Soil0.0003RfD2YES, but only for picachildren
    bariumCiudad CristianaSurface Soil0.07RfD2YES, but only for picachildren
    berylliumOwens-Illinois SurfaceSoil0.005RfD2NO
    berylliumCiudad CristianaSurface Soil0.005RfD2NO
    total mercuryTechnicon Surface Soil0.0003RfD2,3YES, but for adults at only1/22 sampling locations.4
    total mercuryCiudad CristianaSurface Soil0.0003RFD2,3YES, but only for picachildren and only for 1/164sampling locations
    manganeseCiudad CristianaSurface Soil0.14RfD2,5Yes, but only for picachildren
    1 - An explanation of how exposure doses are calculated can be found after Table 12.
    2 - RfD is reference dose.
    3 - EPA's RfD for methyl mercury was used as the health guideline for total mercury.
    4 - At Technicon, 10 samples exceeded the health guidelines only for pica children, 4 samples exceeded them for pica and otherchildren, and one sample exceeded them for adults, and pica and other children.
    5 - This is the RfD for dietary ingestion of manganese. See the Toxicological Evaluation section for a discussion of why thisRfD was used.


    Table 12.

    COMPARISON OF ESTIMATED EXPOSURE DOSE TO HEALTH GUIDELINES FOR INHALATION1
    CONTAMINANTEXPOSUREPATHWAYHEALTHGUIDELINE in µg/m3SOURCEHEALTH GUIDELINEEXCEEDED BYEXPOSURE DOSE
    mercuryOn-Site Air 0.06ChronicMRL2YES for both maximumand average levels
    mercuryOff-Site Air0.06ChronicMRL2YES for both maximumand average levels
    methylene chlorideOn-Site Air105IntermediateMRLYES
    methylene chlorideOff-Site Air105IntermediateMRLNO
    acetoneOn-Site Air1412Acute MRLNO
    acetoneOff-Site Air1412Acute MRLNO
    1 - The air concentrations for a contaminant are compared directly to inhalation minimal risk levels without any additional calculation.
    2 - This chronic minimal risk level (MRL) is for metallic mercury. See the Toxicological Evaluation section for a discussion ofthe use of this MRL.

    Calculation of Exposure Doses for Soil Ingestion

    The exposure doses for soil ingestion were calculated in the following manner. The maximumconcentration for a contaminant was multiplied by the soil ingestion rate for adults, 0.0001kg/day; children, 0.0002 kg/day, or pica children, 0.005 kg/day. (The habit of ingesting largeamounts of soil is called pica.) This product was divided by the average weight for an adult, 70kg (154 pounds) or for a child, 10 kg (22 pounds). Those calculations assume that there isfrequent daily exposure to soil contaminated at the maximum level. A qualitative summary ofthese results can be found in Table 11, Appendix C.

    The adult exposure dose for the maximum on-site arsenic level exceeded the health guideline forarsenic. The exposure doses for pica children at Ciudad Cristiana exceeded the health guidelinesfor arsenic, barium, and manganese, and, at 1/164 sampling locations, total mercury. Thepossible health consequences of exposure to those chemicals which exceeded the healthguidelines will be discussed.

    Calculation of Risk of Carcinogenic Effects

    EPA's Cancer Slope Factor for a contaminant is used to calculate the maximum risk from 70years of exposure. The actual risk of cancer is probably lower than the calculated number. Themethod used to calculate EPA's Cancer Slope Factor assumes that high dose animal data can beused to estimate the risk for low dose exposures in humans (40). The method also assumes thatthere is no safe level for exposure (41). There is little experimental evidence to confirm or refutethose two assumptions. Lastly, the method computes the 95% upper bound for the risk, ratherthe average risk, which results in there being a very good chance that the risk is actually lower,perhaps several orders of magnitude (42).

    Carcinogenic risk from soil ingestion was calculated through the following. For on-site soil, themaximum concentration of a contaminant was multiplied by the soil ingestion rate for workers of0.0001 kg/day. This result is divided by the average adult body weight of 70 kg. This result ismultiplied by 0.43. This is an adjustment for a 30 year exposure, where 30 years is divided bythe exposure length of 70 years built into the slope factor. This product is multiplied by theEPA's Cancer Slope Factor for the contaminant.

    For the soil from Ciudad Cristiana, the maximum concentration of a contaminant was multipliedby the soil ingestion rate for adults of 0.0001 kg/day, then this result is divided by the averageadult body weight of 70 kg. Because the maximum exposure length at Ciudad Cristiana was only6 years, this result was adjusted by 6/70. This product is multiplied by the EPA's Cancer SlopeFactor for the contaminant.

    Cancer slope factors were available for arsenic and beryllium (22). The calculated maximumrisk from daily ingestion of soil contaminated with the maximum concentrations of thesechemicals does not represent an apparent increased risk of cancer. Because of this, carcinogenichealth effects will not be evaluated further.



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