PUBLIC HEALTH ASSESSMENT
FRONTERA CREEK
RIO ABAJO, HUMACAO COUNTY, PUERTO RICO
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).
| CONTAMINANT | FREQ >DL | CONCENTRATION RANGE in ppm | COMPARISONVALUE2 (CV)FORINGESTION | FREQ>CV | |
|---|---|---|---|---|---|
| ppm | Source | ||||
| mercury (total) | 67/122 | 0 - 535 | 200 | RMEG3 | 1/122 |
| mercury(inorganic) | 19/33 | 0 - 7 | 1000 | IEMEG4 | 0/33 |
| arsenic | 9/52 | ND - 430 | 0.4 | CREG | 9/52 |
| beryllium | 1/39 | 0 - 0.35 | 0.2 | CREG | 1/39 |
| 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. | |||||
| CONTAMINANT | CONCENTRATION RANGE in ppm | COMPARISONVALUE (CV) FORINGESTION* | FREQ>CV | |
|---|---|---|---|---|
| ppm | Source | |||
| arsenic | BMDL - 10 | 0.4 | CREG | 11/13 |
| beryllium | 0.3 - 0.47 | 0.2 | CREG | 5/5 |
| 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. | ||||
| CONTAMINANT | CONCENTRATION RANGE in ppm | COMPARISONVALUE (CV) FORINGESTION | FREQ>CV | |
|---|---|---|---|---|
| ppm | Source | |||
| methyl isobutyl ketone | 0 - 4.7 | none | NA2 | |
| methylene chloride | 0 - 1.9 | 0.005 | CREG | 2/2 |
| 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. | ||||
| CONTAMINANT | CONCENTRATION RANGE in µg/m3 | COMPARISON VALUE (CV) FORINHALATION | |
|---|---|---|---|
| Concentration in µg/m3 | Source | ||
| mercury | 0.03 - 2.2 | 0.06 | ChronicEMEG/MRL2 |
| acetone | ND - 618 | 950 | AcuteEMEG/MRL |
| methylene chloride(1989) | 627 - 1956 | 2 | CREG3 |
| methylene chloride(1992) | 46 - 6424 | 2 | CREG3 |
| methylene chloride (1993-1994) | 5.3 - 8124 | 2 | CREG3 |
| 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. | |||
| CONTAMINANT | FREQ>DL | CONCENTRATION RANGE inppm | COMPARISONVALUE (CV)FOR INGESTION2 | FREQ>CV | |
|---|---|---|---|---|---|
| ppm | Source | ||||
| mercury (total) | 91/164 | ND - 0.836 | 0.63 | RMEG | 1/164 |
| mercury(inorganic) | 23/67 | ND - 0.717 | 4 | IEMEG | 0/67 |
| arsenic | 20/32 | BMDL - 4.14 | 0.4 | CREG | 32/325 |
| barium | 32/32 | 47 - 4054 | 100 | RMEG | 31/32 |
| manganese | 32/32 | 434-1,9806 | 10 | RMEG | 32/32 |
| beryllium | 32/32 | 0.1 - 0.286 | 0.2 | CREG | 20/32 |
| 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. | |||||
| CONTAMINANT | FREQ>DL | CONCENTRATION RANGE in ppm | COMPARISONVALUE (CV) FOR INGESTION2 | FREQ>CV | |
|---|---|---|---|---|---|
| ppm | Source | ||||
| mercury (total) | 6/79 | ND - 0.236 | 0.63 | RMEG | 0/79 |
| mercury(inorganic) | 2/79 | ND - 0.182 | 4 | IEMEG | 0/10 |
| barium | 10/10 | 74.1 - 402 | 100 | RMEG | 3/10 |
| manganese | 10/10 | 74.7 - 2,410 | 10 | RMEG | 4/10 |
| beryllium | 9/10 | ND - 0.40 | 0.2 | CREG | 6/10 |
| 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. | |||||
| CONTAMINANT | CONCENTRATION RANGE in µg/m3 | COMPARISON VALUE (CV) FORINHALATION | |
|---|---|---|---|
| Concentration | Source | ||
| mercury | 0.043 - 0.0873 | 0.06 | ChronicEMEG/MRL2 |
| acetone | ND - 16.4 | 950 | AcuteEMEG/MRL |
| methylene chloride(1989) | 30.4 - 55.1 | 2 | CREG3 |
| methylene chloride(1992) | 124,5 | 2 | CREG3 |
| methylene chloride (1993-1994) | 5.6 - 294 | 2 | CREG3 |
| 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
| PATHWAYNAME ANDCONTAMINANT OFCONCERN | EXPOSURE PATHWAY ELEMENTS | |||||
|---|---|---|---|---|---|---|
| SOURCE | ENVIRONMENTAL MEDIA | POINT(S) OFEXPOSURE | ROUTE OFEXPOSURE | EXPOSEDPOPULATION | TIME | |
| TechniconSurface Soil (mercury) | TechniconFacility | Surface Soil | areas ofTechniconfacility withmercury-contaminated soil | ingestion ofor skincontact withmercury-contaminated soil | anyone whocontactedmercury-contaminated soils atTechnicon | past |
| Industrial SurfaceSoil (arsenic) | Natural -except for 2locations | Surface Soil | areas of the sixfacilities witharsenic-contaminated soil | ingestion ofor skincontact witharsenic-contaminated soil | anyone whocontactedarsenic-contaminated soils at thesix facilities | past, present,future |
| Owens-Illinois Soil (beryllium) | Natural | Surface Soil | one location attheOwens-Illinoisfacility | ingestion ofor skincontact withberyllium-contaminatedsoil | anyone whocontactedberyllium-contaminated soils atthis one location | past, present,future |
| Ciudad Cristiana Soil (arsenic, barium,beryllium,manganese, andmercury) | Natural | Surface Soil | for arsenic,barium,beryllium, &manganese anypart of CiudadCristiana; formercury onepart of one yard | ingestion ofor skincontact withcontaminated-soil | anyone whocontactedcontaminatedsoils at CiudadCristiana | past |
| Ambient Air (methylenechloride, acetone,and mercury) | Squibb formethylenechlorideandacetone;mercurysourceunknown | Air | Frontera Creekarea industrialfacilities andresidencesdownwind fromSquibb | inhalation ofcontaminatedair | workers andresidents inFrontera Creekarea | past, present,future (forCiudadCristianaresidents pastexposure only) |
| Surface Water (methylenechloride, andmethyl isobutylketone) | FronteraCreekIndustrialFacilities | Surface Water | that portion ofFrontera Creek that runsthroughindustrial area | ingestion ofor skincontact withcontaminatedsurface water | anyonecontactingsurface water atpoints ofexposure | Past |
| PATHWAYNAME | EXPOSURE PATHWAY ELEMENTS | TIME | ||||
|---|---|---|---|---|---|---|
| SOURCE | ENVIRONMENTAL MEDIA | POINTSOFEXPOSURE | ROUTESOFEXPOSURE | EXPOSEDPOPULATION | ||
| Sediment | Frontera CreekIndustrialFacilities | Sediment | that portionof FronteraCreek thatruns throughindustrialarea | ingestion ofor skincontact withcontaminatedsediment | anyonecontactingsediment atpoints ofexposure | Past |
| EXPOSED POPULATIONS ANDPOTENTIALLY EXPOSEDPOPULATIONS | AFFECTED BY A COMPLETED OR POTENTIAL EXPOSURE PATHWAY* FOR: | ||||||
|---|---|---|---|---|---|---|---|
| Population and Location | Approx# ofPersons | arsenic | barium | beryllium | manganese | mercury | methylene chloride |
| Workers at Technicon | unknown | SSoil Air | SW Air | ||||
| Workers at Frontera CreekIndustrial Facilities | unknown | Ssoil Sediment | Sediment Soil | Air SW | |||
| Ciudad Cristiana Residents | less than10 formercury;1000 forotherfourmetals | SSoil | SSoil | SSoil | SSoil | SSoil at onelocation | Air |
| Other Residents ofFrontera Creek Area | Unknown | 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.
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
| CONTAMINANT | EXPOSUREPATHWAY | HEALTHGUIDELINE INMG/KG/DAY | SOURCE | HEALTH GUIDELINEEXCEEDED BYEXPOSURE DOSE |
|---|---|---|---|---|
| arsenic | Industrial FacilitySurface Soil | 0.0003 | RfD2 | YES |
| arsenic | Ciudad CristianaSurface Soil | 0.0003 | RfD2 | YES, but only for picachildren |
| barium | Ciudad CristianaSurface Soil | 0.07 | RfD2 | YES, but only for picachildren |
| beryllium | Owens-Illinois SurfaceSoil | 0.005 | RfD2 | NO |
| beryllium | Ciudad CristianaSurface Soil | 0.005 | RfD2 | NO |
| total mercury | Technicon Surface Soil | 0.0003 | RfD2,3 | YES, but for adults at only1/22 sampling locations.4 |
| total mercury | Ciudad CristianaSurface Soil | 0.0003 | RFD2,3 | YES, but only for picachildren and only for 1/164sampling locations |
| manganese | Ciudad CristianaSurface Soil | 0.14 | RfD2,5 | Yes, 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. | ||||
| CONTAMINANT | EXPOSUREPATHWAY | HEALTHGUIDELINE in µg/m3 | SOURCE | HEALTH GUIDELINEEXCEEDED BYEXPOSURE DOSE |
|---|---|---|---|---|
| mercury | On-Site Air | 0.06 | ChronicMRL2 | YES for both maximumand average levels |
| mercury | Off-Site Air | 0.06 | ChronicMRL2 | YES for both maximumand average levels |
| methylene chloride | On-Site Air | 105 | IntermediateMRL | YES |
| methylene chloride | Off-Site Air | 105 | IntermediateMRL | NO |
| acetone | On-Site Air | 1412 | Acute MRL | NO |
| acetone | Off-Site Air | 1412 | Acute MRL | NO |
| 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.
