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HEALTH CONSULTATION

Analysis of the Human Exposure Pathway via Surface Water, Sediment, andBiota in Churchill County

FALLON LEUKEMIA PROJECT
FALLON, CHURCHILL COUNTY, NEVADA


TABLES

Table 1.

Churchill County Facilities Permitted Under the National Pollutant Discharge Elimination System Permit Program, 2002
Name Address NPDES No EPA ID SIC Code
A&A Dairy 3550 Tarzyn Road NVA000001 000008055004 0241
Amor IV Corp 5500 Soda Lake Road NVU000041 NV0000736165 NA
Bar-Bell Farms 7770 Flying K Lane NVU000016 000008054094 NA
Beagle Holsteins 3500 Trento Lane NVA000004 000008055034 0241
Clever Dairy 3105 Fischer Place NVA000006 000008054308 0241
Cottonwood Dairy 640 W Corkill Lane NVA000007 000008054318 0241
Diamonte Jerseys 5550 Bottom Road NVA000009 000008055338 0241
Fallon, City of 1575 Wood Dr. NV0020061 NVD000334235 4952
Forest Farms 7770 Flying K Ranch Lane NVA000003 000008055024 0241
Gomes Ranch 3025 Allen Road NVA000012 000008054368 0241
Guazzini Dairy 3855 Austin Highway NVA000013 000008054378 0241
Hillside Dairy 4170 Bass Road NVA000014 000008054388 0241
Hollandia Dairy 340 N Harmon Road NVA000015 000008054398 0241
Jernigan Dairy Churchill County NVA000016 000008054406 0241
Jernigan Ranch NA NVA000026 000008054406 0241
Liberty Jersey Farm 4624 Cox Road NVA000017 000008054416 0241
Lorenzo Septage Site Churchill County NVU000066 000009906130 NA
Mills Jersey Farm 4675 Sheckler Road NVA000020 000008054446 0241
Nunes Dairy 5255 Casey Road NVA000022 000008054466 0241
Oxbow Geothermal Corp Dixie Valley NV0021407 NV0000017053 4911
Perazzo Dairy 1025 Perazzo Lane NVA000023 000008054476 0241
Pine Grove WWTF Latin Road NV0022799 NV0001950633 1629
Regli Dairy 1240 Soda Lakes Road NVA000025 000008054496 0241
Sorenson Dairy 4720 Schurz Highway NVA000029 000008054534 0241
Southfield Dairy 1750 Strasdin Lane NVA000030 000008054544 0241
Star L Dairy 2200 Lone Tree Road NVA000031 000008054554 0241
Travis Dairy 1950 Wade Lane NVA000033 000008054574 0241
Triangle Dairy 4800 Allen Road NVA000034 000008054584 0241
US Navy Naval Air Station Fallon NV0110001 NV9170022173 9711
Whitaker Dairy 2295 Sorensen Road NVA000035 000008054594 0241

SIC (Standard Industry Classification) codes:

0241: dairy farm
1629: heavy construction
4911: electric services
4952: sewerage system
9711: national security
NA: not available


Table 2.

Summary of Environmental Data
Media Source Start Date End Date
Sediment US Geological Survey 1973 1999
Surface water US Geological Survey
US Environmental Protection Agency
National Pollutant Discharge Elimination System
1956 1999
Biota US Geological Survey
Nevada Department of Environmental Protection
US Fish and Wildlife Service
US Environmental Protection Agency
1971 1999


Table 3.

Summary of Detected Chemicals in Sediment Samples for Churchill County (in parts per million)
  Chemical Maximum Concentration Mean Concentration Detects/sample CV CV Type
Halogenated Pesticide or Related Compound 9,10-ANTHRACENEDIONE 0.0544 0.0544 1/9 NA NA
ALDRIN 0.0003 0.0003 1/25 0.04 CREG
CHLORDANE, TECHNICAL 0.045 0.0128 4/17 2 CREG for chlordane
CIS-CHLORDANE 0.00077 0.00077 1/9 2 CREG for chlordane
DDD, P,P'- 0.0032 0.000883 6/30 3 CREG
DDE, P,P'- 0.0021 0.000593 15/29 2 CREG
DDT, P,P'- 0.0002 0.0002 3/28 2 CREG
DIELDRIN 0.0046 0.00112 5/26 0.04 CREG
HEPTACHLOR 0.0001 0.0001 1/25 0.2 CREG
HEPTACHLOR EPOXIDE 0.0005 0.00035 2/26 0.08 CREG
HEXACHLOROCYCLOHEXANE, GAMMA- 0.0047 0.0025 3/26 0.44 PRG
METHOXYCHLOR 0.001 0.001 1/26 10 RMEG
POLYCHLORINATED BIPHENYLS 0.006 0.004 2/26 0.22 PRG
TRANS-CHLORDANE 0.0008 0.0008 1/9 0.44 PRG
Metals ANTIMONY 76 3.72 68/68 31 PRG
ARSENIC 680 81.1 72/72 0.5 CREG
BARIUM 1,200 787 68/68 5,400 PRG
BERYLLIUM 5.1 1.81 65/68 150 PRG
BISMUTH 20 3.2 22/68 NA NA
BORON 140 80 4/4 5,500 PRG
CADMIUM 1.9 0.463 63/38 10 EMEG
CERIUM 89 55.2 67/68 NA NA
CHROMIUM 95 42.8 72/72 2,100 PRG for total chromium
COBALT 240 38.4 68/68 4,700 PRG
COPPER 400 66.8 68/68 2,900 PRG
EUROPIUM 3.1 1.71 37/68 NA NA
GALLIUM 34 16.5 67/68 NA NA
HOLMIUM 2.6 1.5 23/68 NA NA
LANTHANUM 43 29.6 67/68 NA NA
LEAD 73 19.2 68/72 400 PRG
IRON 18,000 14,000 4/4 NA 40 mg/day for children (UL)
LITHIUM 100 31.3 72/72 1,600 PRG
MANGANESE 7,000 1,300 72/72 1,800 PRG
MERCURY 34 1.77 83/84 6,100 PRG for methylmercury
MOLYBDENUM 430 15.8 59/72 3,900 PRG
NEODYMIUM 51 27.1 67/68 NA NA
NICKEL 390 52.2 68/68 1,500 PRG
NIOBIUM 18 7.54 61/68 NA NA
SCANDIUM 17 12.2 64/68 NA NA
SELENIUM 9 1.31 68/72 10 CMEG
SILVER 17 2.24 27/68 3,900 PRG
STRONTIUM 2,300 640 68/68 47,000 PRG
TANTALUM 2.1 1.4 3.68 NA NA
THALLIUM 8.7 4.68 20/41 520 PRG
THORIUM 220 12.7 61/68 NA NA
TIN 11 2.38 39/68 47,000 PRG for inorganic
URANIUM 173 9.08 68/68 16 PRG
VANADIUM 320 136 68/68 550 SSL
YTTERBIUM 3.8 1.93 59/68 NA NA
YTTRIUM 47 18.3 67/68 NA NA
ZINC 290 112 68/68 600 CEMEG
Semi-volatile Organic Compound METHYLPHENANTHRENE 0.0249 0.0249 1/9 NA NA
2,4,6-TRICHLOROPHENOL 0.077 0.077 1/1 60 CREG
2,6-DIMETHYLNAPHTHALENE 0.12 0.0495 8/9 40 naphthalene RMEG for pica
4H-CYCLOPENTA(DEF)
PHENANTHRENE
0.0283 0.0283 1/9 NA NA
ACENAPHTHYLENE 0.014 0.014 1/9 NA NA
ANTHRACENE 0.0342 0.0342 1/9 600 RMEG
BENZO(A)ANTHRACENE 0.0656 NA 1/9 NA NA
BENZO(A)PYRENE 0.0559 NA 1/9 0.1 CREG
BENZO(B)FLUORANTHENE 0.0563 0.0563 1/9 0.62 PRG
BENZO(GHI)PERYLENE 0.0311 0.0311 1/9 0.62 PRG
BENZO(K)FLUORANTHENE 0.0554 0.0554 1/9 0.62 PRG
BENZO{C}CINNOLINE 0.011 0.011 1/9 0.62 PRG
BUTYL BENZYL PHTHALATE 0.0915 0.059 3/9 12,000 PRG
CARBAZOLE 0.0295 0.0295 1/9 32 SSL
CHRYSENE 0.0391 0.0391 1/9 62 PRG
CRESOL, PARA- 0.77 0.193 6/9 310 PRG
DI(2-ETHYLHEXYL)PHTHALATE 0.547 0.0899 9/9 50 CREG
DIETHYL PHTHALATE 0.0216 0.0161 8/9 2,000 RMEG
DI-N-BUTYL PHTHALATE 0.0748 0.0383 8/9 200 RMEG
DI-N-OCTYL PHTHALATE 0.058 0.058 1/9 2,600 SSL
FLUORANTHENE 0.087 0.087 1/9 80 RMEG
INDENO(1,2,3-CD)PYRENE 0.0408 0.0408 1/9 0.62 PRG
NAPHTHALENE 0.0064 0.0064 1/9 40 RMEG for pica
PHENANTHRENE 0.0288 0.0288 1/9 7,800 SSL
PHENOL 0.054 0.0275 5/9 1,000 RMEG
PYRENE 0.0941 0.0941 1/9 60 RMEG

CEMEG: chronic environmental media evaluation guide
CREG: cancer risk evaluation guide for 110-6 excess cancer risk
CV: comparison value
EMEG: environmental media evaluation guide
NA: not available
Pica: A craving to eat nonfood items, such as dirt, paint chips, and clay. Some children exhibit pica-related behavior.
PRG: preliminary remediation goals
RMEG: reference dose media evaluation guide
SSL: soil screen level
UL: tolerable upper intake level


Table 4.

Summary of Chemicals Detected in Churchill County Surface Water Samples (in parts per billion)
  Chemical Maximum concentration Mean concentration Detects/sample CV CV type
Halogenated Pesticide or Related Compound 2,4-D, DISSOLVED 1.6 1.08 3/48 370 PRG
AROCLOR 1242/1248/1260(void) 67,000 26,500 4/4 0.02 CREG
ATRAZINE 0.18 0.18 1/2 400 RMEG
ATRAZINE, DISSOLVED 0.18 0.0136 29/50 400 RMEG
CARBOFURAN 0.035 0.0179 7/50 50 RMEG
CHLORPYRIFOS DISSOLVED 0.006 0.006 1/50 10 PRG
CYANAZINE 0.051 0.051 1/2 1 LTHA
CYANAZINE, DISSOLVED 0.028 0.0158 4/50 1 LTHA
DACTHAL 0.002 0.002 1/49 100 RMEG
DDE, P, P'- 152 152 1/4 0.1 CREG
DEETHYL ATRAZINE, DISSOLVED 0.036 0.0066 15/50 400 RMEG
DIAZINON, DISSOLVED 0.032 0.021 2/50 33 PRG
EPTC 0.042 0.0142 9/50 300 RMEG
HEXACHLOROCYCLOHEXANE, GAMMA- 0.2 0.101 2/7 0.052 PRG
LASSO (Alachlor) 0.041 0.041 1/2 0.84 PRG
MALATHION, DISSOLVED 0.054 0.0406 3/50 200 EMEG
METHOXYCHLOR DISSOLVED 0.02 0.02 1/1 NA NA
MET0LACHLOR, WATER, DISSOLVED 0.008 0.008 1/50 NA NA
METRIBUZIN, DISSOLVED 0.006 0.006 1/50 910 PRG
NAPROPAMIDE 0.004 0.004 1/50 3,700 PRG
PEBULATE 0.009 0.009 2/50 1,800 PRG
PROMETON, DISSOLVED 0.058 0.0154 13/50 550 PRG
PROPARGITE 0.003 0.003 1/50 730 PRG
PROPAZINE 0.147 0.147 1/2 730 PRG
SIMAZINE, DISSOLVED 0.11 0.00945 21/50 0.56 PRG
TEBUTHIORON 0.0218 0.0218 1/50 2,600 PRG
TERBACIL 0.009 0.009 1/50 470 PRG
Inorganic Substance AMMONIA 29,000 913 294/297 30,000 LTHA
AMMONIA NITROGEN 24,000 709 346/361 NA NA
BROMIDE DISSOLVED 290,000 45,800 8/20 NA NA
CARBON DIOXIDE DISSOLVED 32,000 2,630 213/213 NA NA
CHLORIDE DISSOLVED 6,200,000,000 567,000 1091/1099 NA NA
CYANIDE 262 262 1/1 700 RMEG
FLUORIDE DISSOLVED 240,000 1,090 621/670 2,200 PRG
HYDROGEN SULFIDE 130 130 1/1 100 RMEG
IODIDE, DISSOLVED 9 7.5 2/2 NA NA
NITRATE 120,000 9,020 145/145 20,000 RMEG
NITRATE DISSOLVED 10,500 1,240 187/187 20,000 RMEG
NITRATE PLUS NITRITE (AS N) 13,000 594 174/186 NA NA
NITRITE 3,800 112 122/146 3,700 PRG
NITRITE AS N, DISSOLVED 300 36.4 329/578 3,700 PRG
NITRITE DISSOLVED 2,600 184 125/125 3,700 PRG
NITROGEN AMMONIA DISSOLVED 24,000 380 743/882 NA NA
NITROGEN DISSOLVED 27,000 2,000 144/144 NA NA
NITROGEN NITRITE PLUS NITRATE DISSOLVED 9,300 340 481/734 NA NA
PHOSPHATE 2,000 673 67/67 NA NA
PHOSPHATE ORTHO DISSOLVED 30,000 1,580 283/283 NA NA
PHOSPHORUS 31,000 770 896/909 0.7 RMEG
PHOSPHORUS, DISSOLVED 8,200 277 527/549 0.7 RMEG
SILICA DISSOLVED 150,000 280 736/741 NA NA
SULFATE 102,000 37,000 25/25 NA NA
SULFATE DISSOLVED 64,000,000 541,000 868/871 NA NA
Metalloid ALUMINUM 140,000 10,200 24/25 37,000 PRG
ALUMINUM, DISSOLVED 190,000 2,670 201/278 37,000 PRG
ANTIMONY 1 1 1/14 4 RMEG
ANTIMONY, DISSOLVED 120 10.6 46/182 15 PRG
ARSENIC 800 54.5 148/150 0.02 CREG
ARSENIC, DISSOLVED 32,000 237 599/624 0.02 CREG
ARSENIC, SUSPENDED 14 3.13 15/21 0.02 CREG
BARIUM 1,600 164 34/45 2,600 PRG
BARIUM, DISSOLVED 750 73 369/387 2,600 PRG
BARIUM, SUSPENDED 400 86.4 14/14 2,600 PRG
BERYLLIUM 1.9 0.795 6/26 0.016 PRG
BERYLLIUM, DISSOLVED 17 3.99 24/245 0.016 PRG
BORON 3,700 512 20/20 3,300 PRG
BORON, DISSOLVED 1,300,000 7,920 596/603 3,300 PRG
CADMIUM 30 2.18 22/60 18 PRG
CADMIUM, DISSOLVED 4,000 74.9 58/382 18 PRG
CADMIUM, SUSPENDED 29 12.5 4/11 18 PRG
CALCIUM 46,000 27,200 11/11 NA 2,500mg/day UL
CALCIUM, DISSOLVED 1,000,000 49,500 1011/1014 NA 2,500mg/day UL
CHROMIUM 30 8.02 34/63 100 LTHA
CHROMIUM, DISSOLVED 15,000 145 139/482 100 LTHA
CHROMIUM, SUSPENDED 30 12.4 12/13 100 LTHA
COBALT 268 17.5 35/52 2,200 PRG
COBALT, DISSOLVED 3,100 337 39/272 2,200 PRG
COBALT, SUSPENDED 40 12 5/13 2,200 PRG
COPPER 270 20.6 61/72 1,300 MCLG
COPPER, DISSOLVED 2,800 32.3 342/485 1,300 MCLG
COPPER, SUSPENDED 120 17.8 29/31 1,300 MCLG
IRON 140,000 5,500 84/84 11,000 PRG
IRON DISSOLVED 1,100,000 9,890 419/438 11,000 PRG
IRON, FERROUS 33.5 33.5 1/1 11,000 PRG
IRON, SUSPENDED 40,000 6,660 18/18 11,000 PRG
LEAD 120 12.1 43/72 15 Action level
LEAD, DISSOLVED 130 10.7 84/390 15 Action level
LEAD, SUSPENDED 120 21.4 15/25 15 Action level
LITHIUM 120 76.7 6/6 7,300 PRG
LITHIUM, DISSOLVED 8,500 165 546/559 7,300 PRG
MAGNESIUM 10,000 6,900 10/10 NA 350 mg/day UL
MAGNESIUM, DISSOLVED 1,400,000 28,600 988/991 NA 350 mg/day UL
MANGANESE 6,650 534 61/61 500 RMEG
MANGANESE, DISSOLVED 25,000 581 410/434 500 RMEG
MANGANESE, SUSPENDED 1,500 188 31/31 500 RMEG
MERCURY 23,800 297 380/443 110 PRG
MERCURY ORGANIC 0.0218 0.00169 159/160 2 MCL
MERCURY, DISSOLVED 50 0.659 123/390 110 PRG
MERCURY, SUSPENDED 25 2.15 27/27 110 PRG
MOLYBDENUM 940 121 15/29 1,800 PRG
MOLYBDENUM, DISSOLVED 56,000 307 497/633 1,800 PRG
NICKEL 562 32.2 35/37 7,300 PRG
NICKEL, DISSOLVED 8,000 83.6 239/340 7,300 PRG
Metals NICKEL, SUSPENDED 6 3.14 7/7 7,300 PRG
POTASSIUM 20,000 12,700 2/2 NA NA
POTASSIUM, DISSOLVED 2,600,000 17,600 913/914 NA NA
RUBIDIUM DISSOLVED 30 30 1/2 NA NA
SELENIUM 8.01 1.51 21/142 1,800 PRG
SELENIUM, DISSOLVED 21 2.49 37/502 1,800 PRG
SELENIUM, SUSPENDED 1 1 3/3 1,800 PRG
SILVER 8 2.83 12/38 50 RMEG
SILVER, DISSOLVED 5 1.5 20/324 50 RMEG
SILVER, SUSPENDED 8 3.8 5/5 50 RMEG
SODIUM 78,000 35,600 11/11 NA NA
SODIUM, DISSOLVED 150,000,000 707,000 1066/1068 NA NA
STRONTIUM 876 366 15/15 6,000 RMEG
STRONTIUM, DISSOLVED 1,800 443 135/136 6,000 RMEG
THALLIUM, DISSOLVED 220 43 15/22 NA NA
TITANIUM 4.24 1.82 5/13 NA NA
URANIUM 1.1 0.598 9/13 30 MCL
URANIUM, DISSOLVED 19,300 151 225/248 30 MCL
URANIUM, NATURAL, 2 SIGMA 20 9.91 12/12 30 MCL
VANADIUM, DISSOLVED 3,200 80.6 169/308 2,600 PRG
ZINC 470 41 64/72 3,000 CEMEG
ZINC, DISSOLVED 820 34.7 308/445 3,000 CEMEG
ZINC, SUSPENDED 180 38 24/24 3,000 CEMEG
Radionuclide
  ALPHA, DISSOLVED 420 50.3 59/62 NA NA
Semi-volatile organic compound
  DI(2-ETHYLHEXYL)PHTHALATE 5 5 1/5 3 CREG
Volatile organic compound
  1,3-DICHLOROPROPENE, TRANS- 5 5 1/6 1,000 CRMEG
  METHYL ISOBUTYL KETONE 10 10 1/2 160 PRG

CEMEG: chronic environmental media evaluation guide
CREG: cancer risk evaluation guide for 110-6 excess cancer risk
CRMEG: chronic reference dose media evaluation guide
CV: comparison value
LTHA: long term health advisory
MCL: maximum contaminant level
MCLG: maximum contaminant level goal
NA: not available
PRG: preliminary remediation goals
RMEG: reference dose media evaluation guide
UL: tolerable upper intake level


Table 5.

Summary of Biota Data for Total Mercury in Churchill County, Nevada
Report Year Source Sample size Number of species No. of stations Result Range (ppm)
1971
1972
1976
1985
University of NV
Richins et al.
University of NV
NDEP
200
not available
not available
333
7 (fish: white bass, etc.)
1 (fish: carp)
1 (fish: carp)
18 (fish: channel catfish, white bass, black bullhead, yellow perch, Sacramento perch, Sacramento blackfish, walleye, white catfish, green sunfish, largemouth bass, bluegill, carp, rainbow trout, white crappie, Tahoe sucker, mountain sucker, speckled dace, Lahontan redside)
5
1
1
11
0.02-2.72 (wet weight)
0.020-1.360 (wet weight)
5.0-11 (wet weight)
0.06-4.14 (wet weight)
1986
1989
1990
1992
NDEP
NDEP
NDEP
USFWS
not available
not available
not available
43
1 (fish: walleye)
1 (fish: white bass)
2 (fish: white bass, walleye)
4 (fish: carp, white bass, white crappie, channel catfish)
1
1
1
5
1.85-5.23 (wet weight)
0.27-3.28 (wet weight)
0.33-4.77 (wet weight)
0.5-2.7 (wet weight)
1992-94 USGS/USFWS/
USBR/USBIA
    95  
Biological pathways for mercury and selenium 112 (composite) 1 (detritus) <0.04-97.8 (dry weight)
76 1 (algae) <0.02-10.4 (dry weight)
89 1 (detritus) <0.04-38.6 (dry weight)
87 1 (algae) not tested for mercury
55 1 (drift-algae, submergent vascular plants, detritus, daphnids, ostracods, amphipods, corixids, chironomids, brine flies, leeches, odonates) not tested for mercury
12 1 (brine fly) not tested for mercury
Mercury and selenium in edible tissue of waterfowl 161 4 (duck: Mallard, Redhead, Canvasback, Shoveler) <0.5-38.9 (wet weight)
1996 USFWS   7 (pondweed, chironomid, corixid, tui chub, pumpkinseed, and carp)   <0.2-2.7 (dry weight)
1998 EPA
(Lahontan Reservoir data only)
1  
  7 1 (zooplankton) <0.5-2.7 ( 0.31 average)
26 4 (benthic invertebrates-crayfish, caddisfly, midge larvae) not available
    not available
    midge 0.05-0.2
58 6 (fish: carp, green sunfish, mountain sucker, Sacramento blackfish, Tahoe sucker, walleye) 1.47 (whole body), 2.04 (muscle) average
33 2 (birds: swallow, cormorant) 2.1-37 (wet weight)
8 1 (lizard) not available
1999 Mercury characterization in Lahontan Valley wetlands 68 1 (aquatic invertebrate- corixids) 43 <0.5-1.8 (dry weight)
    Total >1468      

NDEP: Nevada Division of Environmental Protection
USGS: US Geological Survey
USFWS: US Fish and Wildlife Service
USBR: US Bureau of Reclamation
USBIA: US Bureau of Indian Affairs
EPA: US Environmental Protection Agency


APPENDIX A: LIST OF ATSDR DOCUMENTS FOR CHURCHILL COUNTY

  1. Agency for Toxic Substances and Disease Registry. Pathway Assessment for Churchill County Surface Soil, Residential Indoor Dust, and Electromagnetic Fields. Atlanta: US Department of Health and Human Services; 2003

  2. Agency for Toxic Substances and Disease Registry. Air Exposure Pathway Assessment, Fallon Leukemia Cluster Investigation. Atlanta: US Department of Health and Human Services; 2003

  3. Agency for Toxic Substances and Disease Registry. Fallon Naval Air Station Evaluation of Potential Exposures from the Fallon JP-8 Fuel Pipeline. Atlanta: US Department of Health and Human Services; 2002

  4. Agency for Toxic Substances and Disease Registry. Public Health Assessment, Naval Air Station Fallon. Atlanta: US Department of Health and Human Services; 2003

  5. Agency for Toxic Substances and Disease Registry. Analysis of Human Exposure Pathways for Pesticide Use in Churchill County. Atlanta: US Department of Health and Human Services; 2003

  6. Agency for Toxic Substances and Disease Registry. Health Consultation for Churchill County Tap Water. Atlanta: US Department of Health and Human Services; 2003

APPENDIX B: ATSDR COMPARISON VALUES AND DEFINITIONS

ATSDR comparison values (CVs) are media-specific concentrations of chemicals that are considered safe under a default exposure scenario. CVs are used as screening values for the identification of contaminants (site-specific substances) that require further evaluation to determine the potential for adverse health effects.

Generally, a chemical is selected for further evaluation because its maximum concentration in air, water, or soil at the site exceeds one of ATSDR's comparison values. However, it cannot be emphasized strongly enough that comparison values are not thresholds of toxicity. Although concentrations at or below the relevant comparison value might reasonably be considered safe, it does not automatically follow that any environmental concentration that exceeds a comparison value would be expected to produce adverse health effects. Indeed, the whole purpose behind these highly conservative, health-based standards and guidelines is to enable health professionals to recognize and resolve potential public health problems before they become actual health hazards. The probability that adverse health outcomes will actually occur as a result of exposure to environmental contaminants depends on site-specific conditions and individual lifestyle and genetic factors that affect the route, magnitude, and duration of actual exposure, and not on environmental concentrations alone.

Screening values based on noncancer effects are obtained by dividing NOAELs (no-observed-adverse-effect levels) or LOAELs (lowest-observed-adverse-effect levels) determined in animal or (less often) human studies by cumulative safety margins (variously called safety factors, uncertainty factors, and modifying factors), which typically range from 10 to 1,000 or more. By contrast, cancer-based screening values are usually derived by linear extrapolation from animal data obtained at high doses, because human cancer incidence data for very low levels of exposure simply do not exist, and probably never will.

Listed and described below are the comparison values that ATSDR has used to select chemicals for further evaluation for this health consultation, along with the abbreviations for the most common units of measure.

EMEG environmental media evaluation guide
RMEG reference dose media evaluation guide
MRL minimal risk level
MCL maximum contaminant level
ppm parts per million, for example, mg/L or mg/kg
ppb parts per billion, for example, µg/L or µg/kg
kg kilogram (1,000 grams)
mg milligram (0.001 grams)
µg microgram (0.000001 grams)
L liter
m3 cubic meter (used in reference to a volume of air equal to 1,000 liters)

Acute exposure is defined as exposure to a chemical for a duration of 14 days or less.

Cancer risk evaluation guides (CREGs) are estimated contaminant concentrations in water, soil, or air that would be expected to cause no more than one excess cancer in a million persons exposed over a lifetime. CREGs are calculated from EPA's cancer slope factors.

Chronic exposure is defined as exposure to a chemical for 365 days or more.

Environmental media evaluation guides (EMEGs) are concentrations of a contaminant in water, soil, or air that are unlikely to be associated with any appreciable risk of deleterious non-cancer effects over a specified duration of exposure. EMEGs are derived from ATSDR minimal risk levels by factoring in default body weights and ingestion rates. Separate EMEGs are computed for acute (<14 days), intermediate (15-364 days), and chronic (>365 days) exposures.

Intermediate exposure is defined as exposure to a chemical for a duration of 15-364 days.

Lowest-observed-adverse-effect levels are the lowest exposure level of a chemical in a study, or group of studies, that produces statistically or biologically significant increase in frequency or severity of adverse health effects between the exposed population and its appropriate control.

Maximum contaminant levels (MCLs) represent contaminant concentrations in drinking water that EPA deems protective of public health (considering the availability and economics of water treatment technology) over a lifetime (70 years) at an exposure rate of 2 liters of water per day.

Minimal risk levels (MRLs) are estimates of daily human exposure to a hazardous substance that is likely to be without an appreciable risk of adverse noncancer health effects over a specified route and duration of exposure.

National Primary Drinking Water Regulations (NPDWR or primary standards) are legally-enforceable standards that apply to public water systems. Primary standards protect drinking water quality by limiting the levels of specific contaminants that can adversely affect public health and known or anticipated to occur in water. They take the form of MCLs or Treatment Techniques.

National Secondary Drinking Water Regulations (NSDWR or secondary standards) are nonenforceable guidelines regarding contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water.

No-observed-adverse-effect level is the dose of a chemical at which there were no statistically or biologically significant increases in frequency or severity of adverse health effects seen between the exposed population and its appropriate control. Effects may be produced at this dose, but they are not considered to be adverse.

Uncertainty factor (UF) is a factor used in operationally deriving the MRL or reference dose or reference concentration from exposure data.


APPENDIX C: DOSE CALCULATIONS

ATSDR established acute (1-14 days) and intermediate (14-365 days) MRLs for inorganic mercury as 0.007 and 0.002 mg/kg/day, respectively. For chronic (more than 365 days) exposure, the MRL for methyl mercury is 0.0003 mg/kg/day. MRLs are estimates of daily human exposure to mercury that are likely to be without an appreciable risk of adverse health effects over a certain time period. The acute and intermediate MRLs for inorganic mercury are based on the no-observed-adverse-effect level (NOAEL) for renal effects in rats, with an uncertainty factor of 100 for extrapolation from animals to humans and human variability. The chronic MRL for methyl mercury is based on the NOAEL for neurodevelopment effects in human, with an uncertainty factor of 4.5 for human variability and modifying factor of the selected study. Organic and inorganic mercury is not known to be carcinogenic by the oral ingestion route [24].

Although most of the mercury found in the environment is in the form of metallic mercury and inorganic mercury compounds, microorganisms convert inorganic mercury to methyl mercury–the form that can accumulate in the food chain. Methyl mercury is also the form of mercury most easily absorbed by the human body. Inorganic mercury does not accumulate in the food chain to any extent [24]. Therefore, the chronic MRL for methyl mercury is used to estimate exposure dose.

The following assumptions were made to estimate maximum concentrations that could result in exceeding chronic MRLs in edible portion of fish, ducks and other biota materials:

  1. The average intake of fish, duck, and other biota materials for freshwater anglers is 8 grams per day (EPA exposure factors hand book), the average intake for children is 4 grams per day.
  2. The average body weight for adults is 70 kilograms (kg) and the average body weight for children is 10 kg.
  3. Total mercury concentrations were used as concentrations of methyl mercury.
  4. Fish and duck consumption is the major source of mercury intake from food and other sources.

The following mathematical formula was used to estimate minimal concentration that could result in exceeding the MRL:

Cmin = (IDf × BW)/(CRxEF)

Where:
Cmin = minimal concentration that could result in exceeding the MRL in edible portion of fish, duck, and other biota materials in milligrams per gram (mg/g)
IDf = ingestion dose in mg/kg/day (respective oral MRLs for mercury)
CR = consumption rate of fish or duck or other biota materials (g/day)
EF = exposure factor (unitless–conservatively assumed to be 1.0)
BW = body weight (kg)

Therefore:
C min for chronic methyl mercury exposure (adult) = (0.0003 mg/kg/day × 70 kg)/ (8 g/day × 1)
= 0.0026 mg/g = 2.6 ppm

C min for chronic methyl mercury exposure (child) = (0.0003 mg/kg/day × 10 kg)/ (4 g/day × 1)
= 0.00075 mg/g = 0.75 ppm


The Federal Emergency Management Agency National Insurance Program Flood Insurance Maps for Churchill County were digitized for spatial analysis. The following maps were digitized.

APPENDIX D:

LIST OF FEDERAL EMERGENCY MANAGEMENT AGENCY MAPS DIGITIZED
Name Community Panel Number Revised Date
City of Fallon, Nevada, Churchill County 320002 0001A January 6, 1999
Churchill County, Nevada 320030 0001-1275 January 6, 1999
Churchill County, Nevada 320030 0645A January 6, 1999
Churchill County, Nevada 320030 0665E January 6, 1999
Churchill County, Nevada 320030 0850C November 15, 1985
Churchill County, Nevada 320030 0855D January 6, 1999


APPENDIX E:

SATELLITE IMAGE INFORMATION
Satellite Resolution Path/Row Date
Landsat 4 60 meters 42/33 June 27, 1983
Landsat 5 30 meters 42/33 August 1, 1993
Landsat 5 30 meters 42/33 June 4, 1995
Landsat 5 30 meters 42/33 June 6, 1996
Landsat 5 30 meters 43/32 January 7, 1997
Landsat 5 30 meters 42/33 January 16, 1997


APPENDIX F: COMMENTS AND ATSDR RESPONSES

ATSDR released a public comment version of this document to the Fallon community in February 2003. Comments were received from various sources, including US Fish and Wildlife Services, USGS, Kennametal Inc., Stone Lions Environmental Corporation, and Pheasant Services. All comments were reviewed by ATSDR staff. The following is a summary of comments and ATSDR responses:

Comment:

Additional data was provided to increase the database for the document. Those reports are:

Hoffman, R.J., and Taylor. 1998. Mercury and suspended sediment, Carson River Basin, Nevada–loads to and from Lahontan Reservoir in flood year 1997 and deposition in reservoir prior to 1983. U.S. Geological Survey Fact Sheet FS - 001- 98.

Hoffman, R.J., R.J. Hallock, T.G. Rowe, M.S. Lico, H.L. Burge, and S.P. Thompson. 1990. Reconnaissance investigation of water quality, bottom sediment, and biota associated with irrigation drainage in and near Stillwater Wildlife Management Area, Churchill County, Nevada, 1986–87. U.S. Geological Survey Water–Resources Investigations Report 89-4105.

Rowe, T.G., M.S. Lico, R.J. Hallock, A.S. Maest, and R.J. Hoffman. 1991. Physical, chemical, and biological data for detailed study of irrigation drainage in and near Stillwater, Fernley, and Humboldt Wildlife Management Areas and Carson Lake, west-central Nevada, 1987-89.

Response:

ATSDR reviewed the first report listed above and added a summary paragraph to the appropriate sections of the document. For the second and third reports, ATSDR reviewed and verified that data in the above reports were included in the federal facility information management system (FFIMs) database used to generate summary tables in the document. In addition, ATSDR verified that biota data in the above reports were also presented in reference 12 used for this document (i.e., US Geological Survey. Detailed study of irrigation drainage in and near wildlife management areas, west central Nevada, 1987-90. Part A, B, C. Carson City, Nevada. US Department of the Interior; 1994). The three reports were added as references.

Comment:

ATSDR uses the term "hazardous substances" when referring to naturally occurring substances. This statement creates the impression that all of the chemicals evaluated in the health consultation are "hazardous", therefore, their mere presence have some inherent risk to the residents of Fallon.

Response:

ATSDR changed the term "hazardous substances" to "chemicals" in the final document.

Comment:

There are three minor corrections for the Background section of the document:

  1. The description of Churchill County given in the first paragraph fails to recognize that the terminus of the Humboldt River basin, Dixie Valley, and Edward Creek Valley also are in the County. None of these areas are in the Carson River drainage. However, it is correct to state that the areas tributaries to the Fallon area are in the Carson River Drainage.
  2. In the listing of hydrographic areas in the Carson River Basin, the document failed to mention the Sierra canyons of the west and east forks of the Carson River. Also, strictly speaking the Carson River flows northeast from Fallon to the Carson Sink. Distrybutary channel and canals direct flows to the southeast of the Carson Lake.
  3. Tahoe dam is part of the Newlands infrastructure and impounds over 1 million acre feet in Lake Tahoe. As such, it is the largest reservoir providing water to the Newlands project.

Response:

  1. For the first comment, ATSDR changed the document accordantly.
  2. In the final document, ATSDR clarified that the hydrographic areas listed are for areas in the state of Nevada only. The majority of the Sierra canyons of the west and east forks of the Carson River are located in California. For the second part of the comment, ATSDR changed the document accordantly.
  3. Lake Tahoe is the largest reservoir providing water to the Newlands project. The Newlands project covers parts of both California and Nevada. The Lahontan Reservoir is the only large storage reservoir in the Carson River Basin in Nevada. Therefore, the document remains the same.

Comment:

In the surface water evaluation section, why use comparison values that are only applicable to drinking water exposures while the surface waters are classified as Class C?

Response:

Although the surface waters are classified as Class C, which indicates that surface water is not used as drinking water, there still is a completed exposure pathway existing for Fallon residents who work or participate in recreational activities in area lakes, the Carson River, and canals. Drinking water standards are used as screening values for the identification of contaminants (site-specific substances) that require further evaluation to determine their potential for adverse health effects. This is an extremely conservative approach for hazard evaluations. For substances detected at concentrations above the screening values (e.g., arsenic, mercury, and certain pesticides at the site), ATSDR uses site-specific exposure scenarios and performs an in-depth evaluation. For the Fallon area site-specific exposure scenarios, the most likely human exposure at the site is occasional ingestion and/or infrequent dermal contact with contaminated surface water by persons working or participating in recreational activities. This kind of infrequent exposure to the contaminated surface water is not likely to result in any adverse health effects.

Comment:

The phase "community concern" should be better defined or removed from the report.

Response:

ATSDR removed the phase "community concern" from the document.

Comment:

The mercury concentrations reported in the document appear to be far higher than those the USGS personnel noted in a brief review of several USGS and USFWS reports.

Response:

ATSDR conducted an extensive cross-reference check for data used in the document for mercury concentrations in sediment. Communications with staff of the Nevada office of the USGS indicated that an error was made in entering all the samples taken on September 15, 1998, and September 16, 1998, into the National Water Information System Web site water-quality data retrieval system. ATSDR revised the final document to reflect the changes. In addition, actions were taken to update local and Web databases by USGS personnel.

Comment:

The report refers to the double-lined evaporation ponds at Kennametal as "leach fields". Generally, leach fields are designed to encourage percolation of fluids into the soil. These evaporation ponds are designed specifically to prevent such percolation.

Response:

ATSDR changed the document to reflect an accurate description of the ponds as "evaporation ponds".

Comment:

The term EMEG is used with no explanation. A list of acronyms would help this report.

Response:

Actually, EMEG was defined at the beginning in the section of ATSDR's evaluation process. ATSDR added an appendix (Appendix B–ATSDR Comparison Values and Definitions) in the final document.

Comment:

For the evaluation of flooding as a potential point of exposure for case and control houses, information on accurate GPS latitude-longitude reading for all wells sampled and site description of where the wells were located relative to structures should provide accurate information needed to reduce any error of mapping house locations.

Response:

ATSDR received GPS latitude-longitude reading for all wells sampled and site descriptions of where the wells were located relative to structures after the public comment release of this document. Therefore, the discussion of flooding events for case and control houses in the final document was revised to reflect the accuracy of new information.

Comment:

Appendix B, assumptions: The assumption used total mercury concentrations for methyl mercury gives exceedingly conservative estimates of risk, particularly in this environment. This area has high total mercury concentrations, with world-class low percentages of methyl mercury. Nonetheless, the absolute concentrations of methyl mercury are among the highest reported in the literature.

Response:

ATSDR acknowledges that using total mercury concentrations to calculate risk resulted a conservative estimate. However, most available data on mercury for this area were for total mercury instead of methyl mercury. Therefore, in the document, ATSDR listed site-specific exposure scenarios which could significantly reduce mercury exposures. The site-specific exposure scenarios included the following statements related to this issue:

  1. The total mercury concentrations are the sum of inorganic and organic mercury compounds. The true methyl mercury concentrations would likely be lower than those used for the risk evaluation.
  2. The absorption and bioavailability of methyl mercury in food might be affected by other dietary components, such as dietary fiber, phytate, and selenium.

Comment:

Following is a list of editorial suggestions made by reviewers:

  • Page 20, references: USGS reports are usually attributed to the authors, rather than to the USGS. Also, for reference 10, whose unpublished PhD dissertation was this?
  • Table 1: NPDES should be spelled out in the table caption. Similarly, SIC should spelled out, or defined in a footnote.
  • Table 3: Should add "concentration" to the column headings, and CV needs to be spelled out or footnoted. Ytterbium has an asterisk next to it, but no footnote defining what the asterisk means. CMEG is not defined in the footnotes. "naphthalene RMEG for pica" is used here, before the term "pica" is defined in the text. Footnote definitions are provided for IEMEG, CRMEG, and LTHA, but none of these acronyms are used in the table.
  • Table 4: Why use ppm in Table 3, but ppb in Table 4? Once again, CV needs to be spelled out or footnoted. EMEG and IEMEG are defined in the footnotes, but not used in the table.
  • Table 5: NDEP, USGS, USFWS, USBR and USBIA should be defined somewhere in the table.
  • Appendix B, second paragraph: Should add "s" to the word "compound".
  • Figures 1 and 2: The legend does not include all shading s and line meanings. Specially, what do the heavy and light dashed lines around the Lahontan Valley and Carson Desert mean?
  • Figure 4: There are other gaging stations in Churchill County, but they are not in the study area. The Figure should be renamed as: Gaging stations in the study area, Churchill County, Nevada.

Response:

ATSDR revised the final document according to the suggestions and the ATSDR Style Manual, FY 2000.


FIGURES

Carson River Basin - Nevada/California: Hydrologic Features
Figure 1. Carson River Basin - Nevada/California: Hydrologic Features

Newlands Project, Nevada/California: Major Project Works
Figure 2. Newlands Project, Nevada/California: Major Project Works

Carson River Basin, Nevada: City of Fallon Vicinity, Canals and Drains
Figure 3. Carson River Basin, Nevada: City of Fallon Vicinity, Canals and Drains

Gaging Station in the Study Area, Churchill County, Nevada
Figure 4. Gaging Station in the Study Area, Churchill County, Nevada

Annual Peak Flow from 1980 Through 2000
Figure 5. Annual Peak Flow from 1980 Through 2000

Location of Case and Control Group Houses and the Floodplain
Figure 6. Location of Case and Control Group Houses and the Floodplain



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