DSHW-2006-008109 - 0901a06880161be2

Ecological Risk Assessment Addendum
ATK Thiokol – Promontory, M-39 and M-636
Utah Division of Solid and Hazardous Waste
July 2006

This addendum was prepared to address deficiencies in the June 2006 ecological risk assessment for M-39 and M-636. The primary deficiencies are the lack of evaluation of invertebrate
receptors for cadmium and silver and no quantitative evaluation of silver.

Cadmium
The 95 percent upper confidence limit of the means (UCL) for cadmium is 6.8 and 3.66 mg/kg for M-39 and M-636, respectively. The UCLs were calculated for a gamma distribution using
the USEPA ProUCL software. At M-39, the hazard quotients are less than one for all guilds except the avian and mammalian insectivores. At M-636, the hazard quotients are also less
than one for all guilds except the avian and mammalian insectivores.

Cadmium Hazard Quotients for M-39

Receptor Guild USEPA 2005
Eco-SSL
(mg/kg) Exposure Point Concentration
(mg/kg)
Hazard Quotient Terrestrial Plants 32 6.8 0.2 Soil Invertebrates 140 6.8 0.05 Avian Herbivore 28 6.8 0.2 Avian Insectivore 0.77 6.8 9 Avian Carnivore 630 6.8 0.01 Mammalian
Herbivore 73 6.8 0.09 Mammalian Insectivore 0.36 6.8 19 Mammalian Carnivore 84 6.8 0.08

Cadmium Hazard Quotients for M-636

Receptor Guild
USEPA 2005
Eco-SSL
(mg/kg) Exposure Point Concentration
(mg/kg)
Hazard Quotient Terrestrial Plants 32 3.66 0.1 Soil Invertebrates 140 3.66 0.03 Avian Herbivore 28 3.66 0.1 Avian Insectivore 0.77 3.66 5 Avian Carnivore 630 3.66 0.01 Mammalian
Herbivore 73 3.66 0.05 Mammalian Insectivore 0.36 3.66 10 Mammalian Carnivore 84 3.66 0.04
While adverse effects cannot be ruled out, the weight of evidence suggests that effects on populations of insectivores would be minimal if they occur. The toxicity database used to
derive the Eco-SSL supports that the lowest-observed-adverse-effects levels (LOAEL) for cadmium are between 7 to 10 times higher doses than the no-observed-adverse-effects levels (NOAEL)
on which the Eco-SSL is based. In addition, the receptors identified at Thiokol are omnivorous and likely obtain only a portion of their metabolic energy from insects. Other food types
in the diet are predicted to have lower concentrations of cadmium than insects. Finally, only a few individuals would potentially be affected because both sites are relatively small
(0.04 acre for M-39 and 0.3 for M-636). Therefore, significant ecological effects from cadmium are unlikely.

Silver

The USEPA has not published Eco-SSLs for silver. Little applicable toxicity data is available for mammals and none was found for invertebrate or avian receptors. The toxicity reference
value proposed by Campbell et al. (2002) of 10 mg/kg/day was selected for mammalian receptors. Calculating doses was hindered by the lack of data for biotransfer factors for estimating
silver concentrations in food items. A factor of one was assumed for plants and 0.81 for prey. These values are not specific for silver and are expected to overestimate exposures.
Biotransfer factors for inorganics are generally less than one (Sample et al., 1998).

Although insectivores are not explicitly evaluated, the evaluation of herbivores should be protective of insectivores. Ingestion rates for plants are higher than for insects because
insects have higher metabolizable energy (Nagy, 1987). This assumes that the biotransfer factor for soil to invertebrates is not significantly higher than the soil to plant biotransfer
factors used.

The calculated hazard quotients for M-39 are less than one, indicating that adverse effects are unlikely. At M-636, the hazard quotient for the rat was three and all other hazard quotients
were less than, or equal to, one. No significant adverse effects are predicted for M-636 because of the small number of individuals potentially exposed at the small site. In addition,
although no LOAEL was available, LOAELs are typically at least three times higher than NOAELs (Lewis et al., 1990) suggesting that a LOAEL-based hazard quotient would not exceed one.

Silver Hazard Quotients for M-39

Receptor Weight
(kg) Food Ingestion Rate
(kg/kg-bw/d) BTF Soil Ingestion
(%) EPC
(mg/kg) Dose
(mg/kg-day) AUF HQ Kangaroo Rat 0.052 0.111 1 2 164 357 0.026667 0.9 Ground Squirrel 0.325 0.05 1 2 164 26 0.133333 0.3 Jackrabbit 2.1 0.071 1 6.3 164 6 0.000889 0.0005 Coyote 10.33 0.045 0.81 2 164 0.6 1.13E-05 7E-07 Notes:
BTF = Biotransfer Factor from ORNL (2000) or Sample et al. (1998)
EPC = Exposure Point Concentration, 95 percent upper confidence limit of the mean
TRV = Toxicity Reference Value Campbell et al. (2002)
AUF = Area Use Factor based on size of site divided by home range
HQ = Hazard Quotient calculated using a toxicity reference value of 10 mg/kd/day
Food Ingestion Rates based on Sample et al. (1997)

Silver Hazard Quotients for M-636

Receptor Weight
(kg) Food Ingestion Rate
(kg/kg-bw/d) BTF Soil Ingestion
(%) EPC
(mg/kg) Dose
(mg/kg-day) AUF HQ Kangaroo Rat 0.052 0.111 1 2 466 1014 0.026667 3 Ground Squirrel 0.325 0.05 1 2 466 73.1 0.133333 1 Jackrabbit 2.1 0.071 1 6.3 466 16.7 0.000889 0.002 Coyote 10.33 0.045 0.8 2 466 1.67 1.13E-05 2E-06 Notes:
BTF = Biotransfer Factor from ORNL (2000) or Sample et al. (1998)
EPC = Exposure Point Concentration, 95 percent upper confidence limit of the mean
TRV = Toxicity Reference Value Campbell et al. (2002)
AUF = Area Use Factor based on size of site divided by home range
HQ = Hazard Quotient calculated using a toxicity reference value of 10 mg/kd/day
Food Ingestion Rates based on Sample et al. (1997)

Home Ranges of Ecological Receptors

Receptor Home Range
(acres) Reference Kangaroo Rat 1.5 O’Farrel (1978) Ground Squirrel 0.3 Smith and Johnson (1985) Jackrabbit 45.0 O’Gara (1978) Coyote 3533.6 Sample et al. (1997)

Conclusions

Although a limited number of individual receptors could be adversely affected, significant adverse effects to populations of ecological receptors from exposure to cadmium and silver
at M-39 and M-636 are not expected.

References

BJC (Bechtel Jacobs Company), 1998 Empirical Models for the Uptake of Inorganic Chemicals from Soil by Plants BJC/OR-133 prepared for the Department of Energy Office of Environmental
Management Oak Ridge National Laboratory

Efroymson et al., 1997. Toxicological Benchmarks for Screening Contaminants of Potential Concern for Effects on Terrestrial Plants: 1997 Revision. Oakridge National Laboratory)

Lewis, SC; Lynch, JR; Nikiforov, AI. 1990. A new approach to deriving community exposure guidelines from “no-observed-adverse-effect-levels.” Reg. Toxicol. Pharmacol., 11: 314-330.

Whitford, W.G., 2001. Invertebrates: Their Effects on the Properties and Processes of Desert Ecosystems. Prakash, I., Editor. Scientific Publishers, Jodhpur, India. Ecology of Desert
Environments. 2001. P. 333-356).

Sample, B. E., J. J. Beauchamp, R. A. Efroymson, G. W. Suter, II, 1998. Development and Validation of Bioaccumulation Models for Small Mammals. Oak Ridge National Laboratory ES/ER/TM-219

Sample, B. E., J. J. Beauchamp R. A. Efroymson, G. W. Suter, II, T. L. Ashwood, 1998a. Development and Validation of Bioaccumulation Models for Earthworms. Oak Ridge National Laboratory
ES/ER/TM-220