iv
i

United States Department of the Interior

Bureau of Land Management

RISK MANAGEMENT CRITERIA

FOR METALS

AT BLM MINING SITES

Karl L. Ford, Ph.D.

Bureau of Land Management

National Science and Technology Center

Denver, CO

Technical Note 390 (revised)

October 2004

BLM/RS/ST-97/001+1703

U.S. DEPARTMENT OF THE INTERIOR

BUREAU OF LAND MANAGEMENT
ii

ACKNOWLEDGEMENT

Portions of this work were supported by

Dynamac Corporation under contract to the

Bureau of Land Management.
iii

HUMAN HEALTH RISK MANAGEMENT CRITERIA

Introduction.......................................................................................................................................1

Human Health Risk Management Criteria......................................................................................... 3

Ecological Risk Management Criteria ................................................................................................ 7

Discussion........................................................................................................................................11

Uncertainty Analysis ........................................................................................................................13

Summary .........................................................................................................................................15

References .......................................................................................................................................17

Appendix A .....................................................................................................................................19
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1

RISK MANAGEMENT CRITERIA FOR METALS

AT BLM MINING SITES

Karl L. Ford, Ph.D.

National Science and Technology Center, Denver, CO

INTRODUCTION

Mining activities have influenced the environment

of Public Lands throughout the West. Tailings from

ore mills have contributed large amounts of heavy

metals into air, water, stream sediments, and soils.

Uncontrolled migration of metal-laden mine tailings

via dust entrainment and erosion continues to

present potentially adverse risks to human health

and wildlife. Recreational demands are increasing

on areas where acute and prolonged exposure to

relatively high metal concentrations in soils,

sediments, and surface waters is occurring. In

some locations, avian and aquatic kills have been

reported.

To address these issues, BLM has developed

acceptable multimedia criteria for the chemicals

of concern (heavy metals) as they relate to recreational use and wildlife habitat on BLM lands. The

primary objective of this report is to establish risk

management criteria (RMC) for human health and

wildlife. Risk management criteria provide numerical

action levels for metals in environmental media.

RMC are designed (1) to assist land managers in

making natural resource decisions and (2) to

support ecosystem management. Ecosystem

management is defined as the skillful use of

ecological, economic, social, and managerial

principles in managing ecosystems to produce, restore, or sustain ecosystem integrity and desired

conditions, uses, products, or values and services

over the long term.

RMC designed to protect human receptors for the

metals of concern were developed using available

toxicity data and standard U.S. Environmental

Protection Agency (EPA) exposure assumptions.

RMC designed to protect wildlife receptors for the

metals of concern were developed using toxicity

values and wildlife intake assumptions reported in

the current ecotoxicology literature. Ingestion of

soil, sediment, and plants is assumed to be the

predominant source of metal exposure for wildlife

receptors.

The contaminants of concern and metal contamination migration pathways were identified from

historical information and site visits. Potential receptors, receptor exposure routes, and exposure

scenarios were identified from on-site visits and

discussions with BLM personnel. Representative

wildlife receptors at risk were chosen using a

number of criteria, including likelihood of

inhabitation and availability of data.

Risk management criteria should be used by the

land manager as a cautionary signal that potential

health hazards are present and that natural resource

management or remedial actions are indicated.

Furthermore, these criteria may be used as target

cleanup levels if remedial action is undertaken.
2
3

HUMAN HEALTH RISK MANAGEMENT CRITERIA

A wide range of possible exposure scenarios was

examined to represent potential human exposures

that might occur on BLM lands. A conceptual site

model was developed for abandoned mining sites

on BLM lands, Figure 1. This model shows the

relationships of waste sources, release mechanisms,

and migration pathways to human and ecological

receptors. Table 1 provides an overview of the

potential human receptors considered and the

media to which they are assumed to be exposed.

All exposure factors are presented in Appendix A.

For the most part, the exposure assumptions used

in the calculation of human health RMC are those

provided in EPA guidance documents.

The equations for the calculations of the human

RMC in soil, sediment, groundwater, surface

water, and fish are presented in Appendix A. The

RMC correspond to a generally recognized acceptable level of health risk, specifically an excess

cancer risk of 1.0E-05 or a noncancer hazard

index of 1.0. An excess cancer risk of 1.0E-05

means that for an individual exposed at these RMC

under the described exposure conditions, there is

only a 1 in 100,000 chance that they would

develop any type of cancer in a lifetime as a result

of contact with the metals of concern on BLM lands.

A hazard index of 1.0 means that the dose of

noncancer metals assumed to be received on BLM

lands by any of the receptors in a medium is lower

than, or the same as, a dose that would not result

in any adverse noncancer health effects.

The risk and hazard levels are consistent with EPA

guidance. The concept behind the RMC is that

people will not experience adverse health effects

from metal contamination on BLM lands during

their lifetimes if exposure is limited to soil,

sediments, and waters with concentrations at or

less than the RMC. To calculate this chance, EPA’s

conservative interpretations of cancer data have

been used; therefore, the likelihood that this risk

has been underestimated is very low.

Primary

Source(s)

Mine

Waste

Primary

Release

Mechanism(s)

Surface Water

Runoff

Infiltration

Percolation

Erosion

Secondary

Source(s)

Surface Water/

Sediments

Groundwater

Soils

Dusts

Wind

Erosion

Potentially complete pathway

Potentially incomplete pathway

Potentially exposure route

Secondary

Release

Mechanism(s)

Erosion

Leaching

Deposition

Migration

Pathway(s)

Direct

Contact

Fish

Ingestion

Dermal

Direct

Contact

Plants

Animals

Air

Exposure

Route(s) Receptor(s)

Offsite

Residents

Recreational

Visitor

Ecological

Receptors

Ingestion

Dermal

Inhalation

Ingestion

Dermal

Ingestion

Inhalation

FIGURE 1. Mine Waste Conceptual Site Model for Human and Ecological Risk.
4

Contaminant of Concern Selection

The contaminant of concern (COC) selection

processes utilized previous work at mining sites.

The selection processes in these investigations were

scientifically rigorous and in accordance with EPA

risk assessment guidance. Therefore, the COCs for

these investigations were combined to form the

COC list for this effort. The COCs for the human

health RMC are antimony, arsenic, cadmium,

copper, lead, manganese, mercury, nickel, selenium,

silver, and zinc. In determining COCs for a given

site, the RMC may be compared with the mean

metals concentrations. Metals exceeding the human

or ecological RMC should be evaluated as COCs.

Lead RMC for the resident were determined from

EPA’s Integrated Exposure Uptake Biokinetic

Model. This model calculates acceptable lead

exposure via ingestion of soil, drinking water, and

food, and via inhalation of air, using 10 ug Pb/dl as

an acceptable blood lead concentration for 95% of

the exposed child population. Lead criteria for

other human receptors were based on available EPA

regulation and guidance.

Exposure Scenarios

The human exposure scenarios were developed to

provide realistic estimates of the types and extent of

exposure which individuals might experience to the

COCs in the water, soils, and sediments on BLM

property. Such exposures might occur to individuals

living on properties adjacent to BLM lands; to

individuals who use BLM lands for camping, boating,

or all-terrain-vehicle (ATV) driving; or to individuals

who work on BLM lands. EPA has published a

number of standard exposure assumptions that are

consistently used to estimate those factors which have

been empirically determined, such as the number of

liters of water an adult drinks in a day, the average

rate of inhalation of dust, or the average number of

years spent in one residence. However, several sitespecific exposure assumptions have been developed

in this report, in addition to the standard EPA assumptions, to provide estimates as closely resembling

probable exposures on BLM property as possible.

The residential scenario was developed because there

are residential properties adjacent to BLM land.

Contamination may migrate from the BLM tracts

to adjoining residential property. All residential

scenario exposure assumptions were obtained

directly from EPA guidance. A variety of recreational

exposure scenarios on BLM lands were also

considered, including camping, swimming, boating,

and ATV driving. The BLM-specific assumptions

were made for the recreational exposure scenarios

in consultation with BLM field offices. Table 2 presents the human health RMC. In the case of metals

posing both cancer and noncancer threats to health,

the lower (more protective) concentration was

selected as the risk management criterion.

The RMC have been divided by 11 metals and by

“n” media that receptors are exposed to (Table 1)

to account for multiple chemical and media

exposures. This ensures that the cumulative

TABLE 1. Human Health Receptors, Media and Exposure Routes

Medium/Exposure Routes

RECEPTOR Groundwater Surface Water Sediments Surface Soils Fish

ingestion ingestion ingestion ingestion inhalation ingestion

Resident

Camper

Boater

Swimmer

ATV Driver

Worker

Surveyor
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TABLE 2. Human Risk Management Criteria

Medium ATV

Resident Camper Driver Worker Surveyor Boater Swimmer

SOILS (mg/kg)

Antimony 3 50 750 100 600 NA NA

Arsenic 1 20 300 12 100 NA NA

Cadmium 3 70 950 100 800 NA NA

Copper 250 5000 70000 7400 59000 NA NA

Lead 400 1000 1000 2000 2000 NA NA

Manganese 960 19000 250000 28000 220000 NA NA

Mercury 2 40 550 60 480 NA NA

Nickel 135 2700 38000 4000 32000 NA NA

Selenium 35 700 9600 1000 8000 NA NA

Silver 35 700 9600 1000 8000 NA NA

Zinc 2000 40000 550000 60000 480000 NA NA

SEDIMENTS (mg/kg)

Antimony NA 62 NA NA NA 221 96

Arsenic NA 46 NA NA NA 166 72

Cadmium NA 155 NA NA NA 553 239

Copper NA 5745 NA NA NA 20517 8884

Lead NA 1000 NA NA NA 1000 1000

Manganese NA 21679 NA NA NA 77424 33525

Mercury NA 46 NA NA NA 166 72

Nickel NA 3094 NA NA NA 11061 4789

Selenium NA 774 NA NA NA 2765 1197

Silver NA 774 NA NA NA 2765 1197

Zinc NA 46455 NA NA NA 165909 71839

SURFACE WATER (ug/l)

Antimony NA 124 NA NA NA 442 192

Arsenic NA 93 NA NA NA 81 144

Cadmium NA 155 NA NA NA 553 239

Copper NA 11490 NA NA NA 41035 17768

Lead NA 50 NA NA NA 50 50

Manganese NA 1548 NA NA NA 5530 2395

Mercury NA 93 NA NA NA 332 144

Nickel NA 6194 NA NA NA 22121 9578

Selenium NA 1548 NA NA NA 5530 2395

Silver NA 1548 NA NA NA 5530 2395

Zinc NA 92909 NA NA NA 331818 143677

effects of all the metals and all of the media are

considered. Therefore, as long as people are not

exposed to metals concentrations exceeding the RMC,

they are not expected to experience adverse effects.
6

TABLE 2. Human Risk Management Criteria (continued)

Medium ATV

Resident Camper Driver Worker Surveyor Boater Swimmer

GROUND WATER (ug/l)

Antimony 0.2 1 NA 3 31 NA NA

Arsenic 0.1 1 NA 0.7 7 NA NA

Cadmium 0.2 2 NA 4 39 NA NA

Copper 18 137 NA 287 2872 NA NA

Lead 15 15 NA 15 15 NA NA

Manganese 2 18 NA 39 387 NA NA

Mercury 0.1 1 NA 2 23 NA NA

Nickel 9 74 NA 155 1548 NA NA

Selenium 2 18 NA 39 387 NA NA

Silver 2 18 NA 39 387 NA NA

Zinc 142 1106 NA 2323 23227 NA NA

FISH (ug/kg)

Antimony 31 65 NA NA NA NA NA

Arsenic 24 48 NA NA NA NA NA

Cadmium 78 161 NA NA NA NA NA

Copper 2907 5984 NA NA NA NA NA

Lead 200 200 NA NA NA NA NA

Manganese 10969 22582 NA NA NA NA NA

Mercury 24 48 NA NA NA NA NA

Nickel 1567 3226 NA NA NA NA NA

Selenium 392 807 NA NA NA NA NA

Silver 392 807 NA NA NA NA NA

Zinc 23505 48390 NA NA NA NA NA

(1) Alternatives include defaulting to local background or evaluating bioavailable fraction.

NA - not applicable
7

ECOLOGICAL RISK MANAGEMENT CRITERIA

Wildlife on the BLM lands may be exposed to metal

contamination via several environmental pathways.

The potential exposure pathways include soil and

sediment ingestion, vegetation ingestion, surface

water ingestion, and airborne dust inhalation. This

report establishes ecological RMC for metals in soil

and sediments. This has been accomplished using

the best data available for the calculations, including ecotoxicological effects data for the metals of

concern, soil-plant uptake factors, representative

wildlife receptors, body weights, and soil and plant

ingestion rates for each receptor.

After careful consideration of regional scientific

literature, and on the basis of field observations,

several wildlife receptors have been selected to represent a range of the types, sizes, and habitats of

birds and mammals representative of temperate

BLM lands. The selected wildlife receptors are the

deer mouse, mountain cottontail, bighorn sheep,

white-tailed deer, mule deer, cattle, elk, mallard,

Canada goose, and trumpeter swan.

The literature was surveyed for toxicity data relevant either to wildlife receptors at the site or to

closely related species. In the absence of available

toxicity data for any receptor, data were selected

on the basis of phylogenetic similarity between

ecological receptors and the test species for which

toxicity data were reported. For example, while no

data on metal toxicity were found in the literature

for trumpeter swans, there were data available on

metal toxicity to Canada geese and mallard ducks.

Accordingly, the goose and duck data were used,

and the toxicity values were adjusted to account

for the differences in body weight and food

ingestion rate between the species. Uncertainty

factors were applied to protect against underestimation of risks to trumpeter swans that might

result from metabolic differences between ducks,

geese, and swans. The COCs for the ecological

assessment included arsenic, cadmium, copper, lead,

mercury, and zinc.

Soil ingestion rates and exposure factors for each

receptor were obtained from the U.S. Fish and Wildlife Service (Beyer, 1994) and unpublished data.

Soil-plant uptake factors were obtained from Baes

(1984). Where no dietary soil intake data were

available for a particular receptor, the soil intake

was assumed to be equal to that of an animal with

similar diets and habits.

RMC were calculated for each chemical of concern in soil based upon assumed exposure factors

for the selected receptors, along with species- and

chemical-specific toxicity reference values (TRVs).

TRVs were computed by chemical of concern for

each wildlife receptor/metal combination, using

the method of Ford, et al. (1992), shown in

Appendix A. Table 3 displays the TRVs.

TRVs represent daily doses of the metals for each

wildlife receptor that will not result in adverse

chronic toxic effects. Wildlife RMC have been

calculated from the TRVs and the assumed intake

of soil/sediment and plants that each receptor will

receive. Therefore, as long as wildlife are not exposed to soils/sediments with concentrations of

metals exceeding the RMC, they are not expected

to experience adverse toxic effects. Table 4 shows

the RMC.
8

As TRV Cu TRV Cd TRV Pb TRV

SPECIES mg/kg/d SOURCE UF mg/kg/d SOURCE UF mg/kg/d SOURCE UF mg/kg/d SOURCE UF

mouse 1.25 Schroeder 2 17.00 CRC 2 0.30 Eisler 85 2 3.000 Schroeder 2

cottontail 0.86 NRC-Rabbit 4 3.44 NRC-Rabbit 4 0.09 NRC-Rabbit 4 0.515 NRC-Rabbit 4

bighorn 0.70 NRC-Sheep 2 0.35 NRC-Sheep 2 0.07 NRC-Sheep 2 0.420 NRC-Sheep 2

WT. Deer 0.24 NRC-Cow 6 0.47 NRC-Cow 6 0.02 NRC-Cow 6 0.142 NRC-Cow 6

M. Deer 0.24 NRC-Cow 6 0.47 NRC-Cow 6 0.02 NRC-Cow 6 0.142 NRC-Cow 6

Elk 0.24 NRC-Cow 8 0.47 NRC-Cow 8 0.02 NRC-Cow 8 0.142 NRC-Cow 8

Robin 0.63 NRC-Poultry 8 3.75 NRC-Poultry 8 0.06 NRC-Poultry 8 0.375 NRC-Poultry 8

Mallard 0.63 NRC-Poultry 8 3.75 NRC-Poultry 8 0.06 NRC-Poultry 8 0.375 NRC-Poultry 8

C. Goose 0.63 NRC-Poultry 8 3.75 NRC-Poultry 8 0.06 NRC-Poultry 8 0.375 NRC-Poultry 8

T. Swan 0.63 NRC-Poultry 8 3.75 NRC-Poultry 8 0.06 NRC-Poultry 8 0.375 NRC-Poultry 8

Cattle 0.70 NRC-Cow 2 1.41 NRC-Cow 2 0.07 NRC-Cow 2 0.425 NRC-Cow 2

Sheep 0.70 NRC-Sheep 2 0.35 NRC-Sheep 2 0.07 NRC-Sheep 2 0.425 NRC-Sheep 2

Hg TRV Zn TRV

SPECIES mg/kg/d SOURCE UF mg/kg/d SOURCE UF

mouse 0.15 CRC 2 26.70 Eisler 93 2

cottontail 0.34 NRC-Rabbit 4 8.60 NRC-Rabbit 4

bighorn 0.07 NRC-Sheep 2 4.20 NRC-Sheep 2

WT. Deer 0.09 NRC-Cow 6 2.36 NRC-Cow 6

M. Deer 0.09 NRC-Cow 6 2.36 NRC-Cow 6

Elk 0.09 NRC-Cow 8 2.36 NRC-Cow 8

Robin 0.25 NRC-Poultry 8 12.50 NRC-Poultry 8

Mallard 0.25 NRC-Poultry 8 12.50 NRC-Poultry 8

C. Goose 0.25 NRC-Poultry 8 12.50 NRC-Poultry 8

T. Swan 0.25 NRC-Poultry 8 12.50 NRC-Poultry 8

Cattle 0.28 NRC-Cow 2 7.00 NRC-Cow 2

Sheep 0.28 NRC-Sheep 2 4.20 NRC-Sheep 2

Abbreviations:

crc p._ : Handbook of Chemical Toxicity Profiles of Biological Species. Ramamoorthy, et al., 1995. Lewis Publishers.

nrc : National Research Council, 1980. Mineral Tolerance of Domestic Animals.

Eisler p._ : Eisler, Fish and Wildlife Service Synoptic Reviews, various dates.

UF : Total uncertainty factor.

Note : nrc TRVs were calculated as the product of the dietary concentration times the kg plant ingestion divided by the body weight. Uncertainty factors were

 applied according to the extrapolation approach above.

TABLE 3. Toxicity Reference Values (mg/kg/d)
9

TABLE 4. Wildlife and Livestock Risk Management Criteria for Metals in Soils (mg/kg)

Arsenic Cadmium Copper Lead Mercury Zinc

Deer Mouse 230 7 640 142 2 419

Cottontail 438 6 358 172 15 373

Bighorn Sheep 387 9 64 152 6 369

White-Tailed Deer 319 3 128 124 11 267

Mule Deer 200 3 102 106 9 222

Elk 328 3 131 127 11 275

Cattle 419 15 413 244 45 1082

Sheep 352 12 86 203 38 545

Mallard 116 1 141 59 4 196

Canada Goose 61 2 161 34 6 271

Trumpeter Swan 76 2 201 43 7 340

Robin 4 0.3 7 6 1 43

Median 275 3 136 125 8 307

Aquatic Plant Ingestion

Aquatic plants such as Arrowhead (Sagitarria sp.)

appear to accumulate metals and store them in their

tubers. Arrowhead tubers are eaten by swan and

other waterfowl. Of these consumers, swans reportedly eat the most; the plant constitutes 5-10%

of the diet of trumpeter swans and muskrats.

Elevated lead levels in Sagitarria have been reported

(Krieger, 1990). The mean value detected in tubers

was 159 ppm. The trumpeter swan body weight is

approximately 8.17 kg, and the daily ingestion rate

is 386 grams/day. Assuming the Sagitarria is 10%

of the swan’s diet, a swan’s lead intake might be

0.75 mg/kg/day. As shown in Table 3, the swan

TRV is 0.125 mg/kg/day. Thus, it can be seen that

the lead intake by waterfowl from Sagitarria alone

may represent a chronic (or possibly acute) lead

poisoning hazard for waterfowl.

Aquatic Life Protection

Surface waters are often contaminated by mining

sites. Table 5 presents EPA ambient water criteria

for metals and cyanide for the protection of aquatic

life and humans ingesting water and fish (EPA,

1986). States may have other criteria.
10

TABLE 5. Selected EPA Ambient Water Quality Criteria (micrograms/liter).

Note: States may have other criteria.

Freshwater Freshwater Human

Aquatic Life Aquatic Life Water+Fish

Metal Acute Exposure Chronic Exposure Ingestion

Antimony NA NA 5.6

Arsenic (V) 340 150 0.018

Barium NA NA 1000

Cadmium+ 2 0.25 NA

Chromium (III) 570 74 NA

Copper+ 13 9 NA

Cyanide (free) 22 5.2 700

Iron NA 1000 300

Lead+ 65 2.5 NA

Manganese NA NA 50

Mercury 1.4 0.77 0.3*

Nickel+ 470 52 610

Selenium NA 5 170

Silver+ 3.2 NA NA

Thallium NA NA 1.7

Zinc+ 120+ 120 7400

+ Computed from hardness; (100 mg/l used. See reference equation for other hardnesses).

Source: EPA, 2002.

* Fish tissue (ppm), methyl mercury

NA - Not available
11

DISCUSSION

It is anticipated that the RMC will be used as a

benchmark concentration to which environmental concentrations may be compared, assisting land

managers in protecting humans and wildlife on

BLM lands. These criteria should be used by the

land manager as a cautionary signal that potential

health hazards are present and that natural resource

management or remedial actions are indicated. It

is suggested that exceedances of the criteria be

interpreted as follows:

• less than criteria: low risk

• 1-10 times the criteria: moderate risk

• 10-100 times the criteria: high risk

• >100 times the criteria: extremely high risk

Given the uncertainties associated with the ecological RMC and the values inherent in ecosystem

management, moderate risk may be addressed by

management and or institutional controls, whereas

high risk may require remediation. Additionally,

the criteria may be used as target cleanup levels if

remedial action is undertaken. The human RMC

may be modified to be less stringent if the number

of metals present are fewer or if background concentrations are locally elevated.

Data from this study indicate the importance of

plant accumulation of metals. Some authors

believe that copper and zinc are self-regulated;

however, there is evidence that copper and zinc

can be accumulated in target organs such as the

kidneys and liver and can cause toxicity. Cadmium

and mercury can be bioaccumulated in tissue from

one trophic level to the next, resulting in the

so-called "secondary poisoning" of top consumers

in a food web. The wildlife criteria also protect

soil macrofauna such as earthworms and insects

that are important parts of terrestrial food chains

and detritivores important to nutrient cycling in

ecosystems.

Wildlife RMC are consistent with no-effect metal

concentrations found for plants (Kabata-Pendias,

1992), for aquatic life associated with stream sediment (EPA, 1977), and for soil organisms responsible for fertility and nutrient cycling (Will and

Suter, 1994). For wildlife, this model indicates that

the majority of the intake for copper, cadmium,

mercury, and zinc derives from ingestion of plants;

the majority of intake of arsenic and lead derives

from soil ingestion.

Various approaches have been suggested for

selecting a criterion suitable for protecting groups

of species, communities, or ecosystems; however,

none have been widely accepted. For the purposes

of this Technical Note, the median (Table 4) is

recommended at the present time.

In summary, there are numerous applications of

the RMC, depending on the medium and the type

of exposure considered. Based on comparisons to

available sampling data from mining sites, it is

likely that humans are occasionally and wildlife

receptors are frequently at risk from adverse toxic

effects associated with metal contamination in soils

and sediments. In order to ensure proper interpretation of the significance of these results, all of the

RMC in this paper must be considered in light of

the assumptions used in their development.

The contributions of the assumptions used in this

report to the degree of uncertainty are described

below.
12
13

UNCERTAINTY ANALYSIS

Numerous toxicological interactions are known

among the metals of concern. Some are protective (e.g., zinc, copper, and calcium protect against

cadmium and lead), while others are synergistic

(i.e., toxic effects are cumulative). These effects

can be concentration dependent and species

dependent. The COCs on BLM lands may have

synergistic effects on human or wildlife receptors.

Cumulative effects were quantitatively dealt with

for the human assessment, but not for the ecological assessment. Because species-specific toxicity

data were not available for each wildlife receptor

and each metal, the ecological RMC for each metal

were calculated as though each was the only metal

present. As a result, the current ecological RMC

for each receptor/metal combination may be

numerically larger than if the synergistic effect of

simultaneous exposure to all the metals could be

estimated.

After careful research into the current wildlife

management literature, toxicity data were selected

from test species that were phylogenetically similar as possible to likely receptors. The highest potential for uncertainty in the wildlife calculations

is associated with the protection against a greater

toxic response to any metal by wildlife, as compared to the toxic response to the same metal by

laboratory animals. The amount of uncertainty in

such cases would be directly proportional to the

extent of phylogenetic difference between test and

receptor organisms. To minimize this uncertainty,

test species data were selected from animals as

closely related to the ecological receptors for the

region as possible. Most values selected for use in

the wildlife risk management calculations are for

test species from the same biological order as the

ecological receptor, except for the use of poultry

(Galliformes) test species to estimate effects of

cadmium, manganese, and zinc on waterfowl

(Anseriformes). To account for phylogenetic

differences, uncertainty factors were used (Ford,

et al., 1992).

Phylogenetic and intraspecies differences between

test species and ecological receptors have been

taken into account by the application of uncertainty

factors in derivation of critical toxicity values. These

uncertainty factors were applied to protect wildlife receptors which might be more sensitive to

the toxic effects of a metal than the test species.

The uncertainty factors were applied to the test

species toxicity data in accordance with a method

developed by BLM. In accordance with this

system, a divisor of two (2) was applied to the

toxicity reference dose for each level of phylogenetic difference between the test and wildlife

species, (e.g., individual, species, genus, and family).

Reasonable uncertainty factors have also been

applied to account for the differences between test

administration conditions (length of exposure) and

conditions in the wild.

Toxic doses for each metal were selected from the

literature without regard to the specific metal

compound administered in the toxicity test. Metal

toxicity varies greatly with the solubility of the

metallic compound, which determines the ease of

passage through biological membranes. This

bioavailability factor results in a tendency to overestimate actual human and wildlife RMC because

the geochemical species present in soils, sediments,

or waters of mining sites are expected to be of

lower solubility. Collection of bioaccessibility or

mineralogical data on a site may permit an upward

adjustment of the RMC (Ruby et al., 1993).

The process of calculating human health RMC

using a target hazard index and target excess lifetime cancer risk has a number of inherent sources

of uncertainty. There is statistical quantitative uncertainty associated with the estimates of exposure

used in the calculation of the human health RMC.

Furthermore, EPA applies uncertainty factors when

establishing reference doses and cancer potency

slope factors by using animal data to develop

human toxicity criteria. The degree of uncertainty

in the human health RMC cannot be completely

quantified; however, due to the conservative

assumptions incorporated in the standard EPA

default exposure factors and EPA toxicity criteria

used, and due to the conservative nature of the
14

exposure assumptions used for this report, the

human health RMC are unlikely to underestimate

the true criteria.

For some metal-wildlife combinations, there

was a dearth of chronic toxicity data available.

Uncertainty exists with the extrapolation process

used for wildlife; however, it is conservative and

consistent with other work performed with plants

and domestic animals (Kabata-Pendias, 1992;

National Academy of Sciences, 1980) and soil

organisms (Will and Suter, 1994).
15

SUMMARY

Interpretation of the significance of the human

health RMC depends on the current and future

land uses envisioned and the potential exposures

that could occur. An in-depth comparison between

the human health RMC and the actual concentrations of metals on BLM lands is beyond the scope

of this paper. A high degree of confidence can be

placed in the RMC, because they have been

calculated using verifiable scientific data and valid

exposure assumptions. Furthermore, a comparison

between the risk management calculations and

background concentrations shows that, for the most

part, all of the calculated wildlife and human RMC

are higher than reported background concentrations.

The wildlife RMC are also protective of plants. As

would be expected, the wildlife risk management

criteria are generally numerically larger than the

published soil and sediment background concentrations in the western U.S. (Table 4). However,

the increment is often only a few ppm to 50 ppm,

suggesting that only slightly elevated concentrations

may indicate risk. Based on the size of the

exceedances of the risk management criteria routinely

found at mining sites, it appears that soil/sediment

and plant ingestion may currently be causing metal

toxicity in wildlife receptors on Public Lands. Furthermore, there are additional sources of metals for

regional wildlife, including contaminated surface

water and contaminated airborne dust. Consideration of wildlife exposure to metals in plants

indicates that plant ingestion may be a significant

exposure route that should be considered when

making risk management decisions.

The RMC developed in this paper are conservative

and are designed specifically to protect against

underestimation of risks to wildlife or human receptors. Therefore, it may be concluded that for

any area where environmental metal concentrations

are lower than the RMC, such media are not likely

to pose a risk of adverse effects to wildlife or

humans. Given the uncertainties associated with

the ecological RMC and the values inherent in

ecosystem management, moderate risk may be

addressed by management and or institutional

controls, whereas high risk may require

remediation.
16
17

REFERENCES

Baes, C.F., et al. 1984. A Review and Analysis of

Parameters for Assessing Transport of Environmentally Released Radionuclides through

Agriculture. Oak Ridge National Laboratory.

Beyer, W.N., E. Connor, and S. Gerould. 1994.

Survey of Soil Ingestion By Wildlife. Journal

of Wildlife Management, Vol. 58.

Burt, W.H. 1976. A Field Guide to the Mammals,

North America, North of Mexico, third edition.

Houghton Mifflin Company, Boston.

Eisler, R. 1988. Arsenic Hazards to Fish, Wildlife,

and Invertebrates: A Synoptic Review. Biological Report 12, U.S. Fish and Wildlife Service.

January, 1988.

Eisler, R. 1985. Cadmium Hazards to Fish, Wildlife,

and Invertebrates: A Synoptic Review. Biological

Report 2, U.S. Fish and Wildlife Service. July,

1985.

Eisler, R. 1987. Mercury Hazards to Fish, Wildlife,

and Invertebrates: A Synoptic Review. Biological

Report 85(1.10), U.S. Fish and Wildlife Service.

April, 1987.

Eisler, R. 1993. Zinc Hazards to Fish, Wildlife, and

Invertebrates: A Synoptic Review. Biological

Report 26, U.S. Fish and Wildlife Service. April,

1993.

Elinder, C.G., and L. Friberg. 1986. Antimony.in

Handbook on the Toxicology of Metals, 2nd

edition. New York: Elsevier Science Publishers.

Federal Register (FR). 1991. 56 FR 26460.

Ford, K.L., F.M. Applehans, and R. Ober. 1992.

Development of Toxicity reference Values for

Terrestrial Wildlife. Proceedings of the HMC/

Superfund 1992 Conference. 803-812.

Friberg, L., T. Kjellstrom, and G. F. Nordberg. 1986.

Cadmium.in Handbook on the Toxicology

of Metals, 2nd edition. New York: Elsevier

Science Publishers.

Hart, D.R., J. Fitchko, and P. McKee. September

1988. Development of Sediment Quality

Guidelines. Phase II - Guidelines Development.

Beak Consultants, Ltd., Brampton, Ontario,

Canada.

Ishinishi, N., K. Tsuchiya, M. Vahter, and B. A.

Fowler. 1986. Arsenic.in Handbook on the

Toxicology of Metals, 2nd edition. New York:

Elsevier Science Publishers.

Kabata-Pendias, A, H. Pendias. 1992. Trace Metals

in Soil and Plants. CRC Press, Ann Arbor. 385 pp.

Krieger, R.I. 1990. Toxicity and Bioavailablity Studies of Lead and Other Elements in the Lower

Coeur d’Alene River. Prepared for Coeur

d’Alene District, Bureau of Land Management.

Technical Bulletin 90-3.

Martin, A.C., H.S. Zim, and A.L. Nelson. 1961.

American Wildlife and Plants: A Guide to

Wildlife Food Habits. New York: Dover

Publications, Inc. 500 pp.

Nagy, K. 1987. Field Metabolic Rate and Food

Requirement Scaling. Ecological Monographs.

57:111-128.

National Academy of Sciences. 1980. Mineral

Tolerance of Domestic Animals. Washington D.C.

OME. 1988. Ontario Ministry of the Environment. Guidelines for the Management of

Dredged Material. Ontario Ministry of the

Environment. Toronto, Ontario, Canada.
18

Persaud, D., R. Jaagumagi, and A. Hayton. May

1991. The Provincial Sediment Quality

Guidelines, Water Resources Branch, Ontario

Ministry of the Environment (Draft).

Puls, R. 1989. Mineral Levels in Animal Health:

Diagnostic Data. Clearbrook, British Columbia,

Canada: Sherpa International. 240 pp.

Shacklette, H.T. and J.G. Boerngen. 1984. Element

Concentration in Soils and Other Surficial

Materials of the Conterminous United States.

USGS Professional Paper 1270.

Ruby, M.V., A. Davis, T. Link, R. Schoof, R. Chaney,

G. Freeman and P. Bergstrom, 1993. Development of an in-vitro screening test to evaluate

the in-vivo bioaccessability of ingested mine

waste lead. Environmental Science and Technology, Vol. 27, No. 13.

Taylor, M.C., A. Demayo and S. Reeder, 1980. Inorganic Chemical Substances-Silver, Guidelines

for Surface Water Quality. in Remedial Investigation Report, Buckingham County Landfill

Site, Buckingham County, Virginia. Engineering Science, Inc., October, 1992.

Terres, J.K. 1991. The Audubon Society Encyclopedia of North American Birds. Wings Books,

New York.

U.S. Environmental Protection Agency (USEPA).

1991. Risk Assessment Guidance for

Superfund, Part B. Publication 9285.7-01B

U.S. Environmental Protection Agency (USEPA).

1993a. Integrated Risk Information System

(IRIS), On-line database, accessed September,

1993.

U.S. Environmental Protection Agency (USEPA).

1993b. Risk-Based Concentration Table,

Third Quarter 1993. Roy L. Smith, Senior

Toxicologist. Technical Support Section,

USEPA Region III.

U.S. Environmental Protection Agency (USEPA).

1993c. Health Effects Assessment Summary

Tables, Annual Update. Office of Solid Waste

and Emergency Response. EPA 540-R-93-058.

U.S. Environmental Protection Agency (USEPA).

1993d. Integrated Exposure Uptake Biokinetic

Model (IEUBK), Version 6.

U.S. Environmental Protection Agency (USEPA).

1993e. Standards for the Use or Disposal of

Sewage Sludge. FR 9248-9392.

U.S. Environmental Protection Agency (USEPA).

1993f. Wildlife Exposure Factors Handbook.

EPA/600/R-93/187a.

U.S. Environmental Protection Agency (USEPA).

2002. National Recommended Water Quality

Criteria. EPA 822-R-02-047

Will, M.E. and G.W. Suter. 1994. Toxicological

Benchmarts for Screening Potential Contaminants of Concern for Effects on Soil and Litter

Invertebrates and Heterotrophic Processes.

Oak Ridge National Laboratory, Oak Ridge, TN.
19

APPENDIX A

EQUATION 1: Risk management criteria calculation based upon the noncarcinogenic hazards from exposure to groundwater: residential, campground host, camper,

recreation maintenance worker, and surveyor receptors

Where:

CW = Chemical Risk Management Criteria in Water (mg/L)

THI = Target Hazard Index (unitless)

RfDo = Oral Chronic Reference Dose (mg/kg-day)

BW = Body Weight (kg)

NCAT = Noncarcinogenic Averaging Time (period over which exposure resulting in

noncarcinogenic effects is averaged - days)

IR = Ingestion Rate (L/day)

EF = Exposure Frequency (days/year)

ED = Exposure Duration (years)

NNCO = Number of COCs with an Oral Chronic Reference Dose (unitless)

EQUATION 2: Risk management criteria calculation based upon the carcinogenic risks from

the exposure to groundwater: residential, campground host, camper, recreation maintenance worker, and surveyor receptors

Where:

CW = Chemical Risk Management Criteria in Water (mg/L)

TR = Target Excess Individual Lifetime Cancer Risk (unitless)

CAT = Carcinogenic Averaging Time (period over which exposure resulting in

carcinogenic effects is averaged - days)

CPSo = Oral Carcinogenic Potency Slope (mg/kg-day)- 1

EF = Exposure Frequency (days/year)

NCO = Number of COCs with an Oral Carcinogenic Potency Slope (unitless)

BWA = Body Weight, Adult (kg) BWC = Body Weight, Child (kg)

IRA = Ingestion Rate, Adult (L/day) IRC = Ingestion Rate, Child (L/day)

EDA = Exposure Duration, Adult (years) EDC = Exposure Duration, Child (years)

C (mg/L) = W

THI RfD BW NCAT * * * o

IR EF ED N * * * NCO

C (mg/L) = W

TR CAT * * CPS EF N o CO

A

 * *

BW BWC +

IR ED A A * IR ED C C *
20

EQUATION 3: Risk management criteria calculation based upon the noncarcinogenic hazards from exposure to surface water: campground host, camper, boater, and

swimmer receptors

Where:

CW = Chemical Risk Management Criteria in Surface Water (mg/L)

THI = Target Hazard Index (unitless)

RfDo = Oral Chronic Reference Dose (mg/kg-day)

BW = Body Weight (kg)

NCAT = Noncarcinogenic Averaging Time (period over which exposure resulting in

noncarcinogenic effects is averaged - days)

CR = Contact Rate (L/hour)

ET = Exposure Time (hours/event)

EF = Exposure Frequency (events/year)

ED = Exposure Duration (years)

NNCO = Number of COCs with an Oral Chronic Reference Dose

EQUATION 4: Risk management criteria calculation based upon the carcinogenic risks from

exposure to chemicals in surface water: campground host, camper, boater,

and swimmer receptors

Where:

CW = Chemical Risk Management Criteria in Surface Water (mg/L)

TR = Target Excess Individual Lifetime Cancer Risk (unitless)

CAT = Carcinogenic Averaging Time (period over which exposure resulting in

carcinogenic effects is averaged - days)

CPSo = Oral Carcinogenic Potency Slope (mg/kg-day)- 1

CR = Contact Rate (L/hour)

ET = Exposure Time (hours/event)

EF = Exposure Frequency (events/year)

NCO = Number of COCs with an Oral Carcinogenic Potency Slope (unitless)

BWA = Body Weight, Adult (kg) BWC = Body Weight, Child (kg)

EDA = Exposure Duration, Adult (years) EDC = Exposure Duration, Child

* * * *

C (mg/L) = W

THI RfD BW NCAT * * * o

CR ET EF ED NNCO

C (mg/L) = W

TR CAT *

CPS CR ET EF N o * * * * CO

BWA BWC

* +

EDA EDC
21

EQUATION 5: Risk management criteria calculation based upon the noncarcinogenic hazards from exposure to sediments: campground host, camper, boater, and

swimmer receptors

Where:

CS = Chemical Risk Management Criteria in Sediments (mg/kg)

THI = Target Hazard Index (unitless)

RfDo = Oral Chronic Reference Dose (mg/kg-day)

BW = Body Weight (kg)

NCAT = Noncarcinogenic Averaging Time (period over which exposure resulting in

noncarcinogenic effects is averaged - days)

IR = Ingestion Rate (mg/day)

CF = Conversion Factor (kg/mg)

EF = Exposure Frequency (days/year)

ED = Exposure Duration (years)

NNCO = Number of COCs with an Oral Chronic Reference Dose (unitless)

EQUATION 6: Risk management criteria calculation based upon the carcinogenic risks from

exposure to sediments: campground host, camper, boater, and swimmer

receptors

Where:

CS = Chemical Risk Management Criteria in Sediments (mg/kg)

TR = Target Excess Individual Lifetime Cancer Risk (unitless)

CAT = Carcinogenic Averaging Time (period over which exposure resulting in

carcinogenic effects is averaged - days)

CPSo = Oral Carcinogenic Potency Slope (mg/kg-day)- 1

CF = Conversion Factor (kg/mg)

EF = Exposure Frequency (days/year)

NCO = Number of COCs with an Oral Carcinogenic Potency Slope (unitless)

BWA = Body Weight, Adult (kg) BWC = Body Weight, Child (kg)

IRA = Ingestion Rate, Adult (mg/day) IRC = Ingestion Rate, Child (mg/day)

EDA = Exposure Duration, Adult (years) EDC = Exposure Duration, Child (years)

C (mg/kg) = S

THI RfD BW NCAT * * * o

IR CF EF ED N * * * * NCO

C (mg/kg) = S

TR CAT *

CPS CF EF N o * * * CO

BWA BWC +

IR ED A A * IR ED C C * *
22

EQUATION 7: Risk management criteria calculation based upon the noncarcinogenic hazards from exposure to soil: residential, campground host, camper, ATV driver,

recreation maintenance worker, and surveyor receptors

Where:

Cs = Chemical Risk Management Criteria in Soil (mg/kg)

THI = Target Hazard Index (unitless)

NCAT = Noncarcinogenic Averaging Time (period over which exposure resulting in

noncarcinogenic effects is averaged - years)

EF = Exposure Frequency (days/year)

RfDo = Oral Chronic Reference Dose (mg/kg-day)

IRs = Age Ajusted Soil Ingestion Rate (mg-yr/kg-day)

CF = Conversion Factor (kg/mg)

NNCO = Number of COCs with an Oral Chronic Reference Dose (unitless)

RfDi = Inhalation Chronic Reference Dose (mg/kg-day)

IHR = Inhalation Rate (m3/hr)

PEF = Particulate Emission Factor (m3/kg)

NNCI = Number of COCs with an Inhalation Chronic Reference Dose (unitless)

MN = Number of Media

EQUATION 8: Risk management criteria calculation based upon the carcinogenic risks from

exposure to soil: residential, campground host, camper, ATV driver, recreation maintenance worker, and surveyor receptors

Where:

Cs = Chemical Risk Management Criteria in Soil (mg/kg)

TR = Target Excess Individual Lifetime Cancer Risk (unitless)

AT = Carcinogenic Averaging Time (period over which exposure resulting in

carcinogenic effects is averaged - years)

EF = Exposure Frequency (days/year)

SFo = Oral Carcinogenic Potency Slope (mg/kg-day)- 1

CF = Conversion Factor (kg/mg)

NCO = Number of COCs with an Oral Carcinogenic Potency Slope (unitless)

MN = Number of Media

IRs = Age Ajusted Soil Ingestion Rate (mg-yr/kg-day)

SFi = Inhalation Carcinogenic Potency Slope (mg/kg-day)- 1

NCI = Number of COCs with an Inhalation Carcinogenic Potency Slope (unitless)

IR = Inhalation Rate (m3/hr)

* *

CS (mg/kg) = THI 365 NCAT * *

EF M*

RfDo +

IR CF N S NCO

* * *

RfDi

N IHR 1/PEF NNCI

CS (mg/kg) = TR AT 365/ EF M SF CF IR SF /N IR 1/PEF * * * * * * * * o S + N I
23

EQUATION 9: Risk management criteria calculation based upon the noncarcinogenic hazards from the ingestion of chemicals in fish tissue: residential, campground

host, and camper receptors

Where:

CF = Chemical Criteria in Fish (mg/kg)

THI = Target Hazard Index (unitless)

RfDo = Oral Chronic Reference Dose (mg/kg-day)

BW = Body Weight (kg)

NCAT = Noncarcinogenic Averaging Time (period over which exposure resulting in

noncarcinogenic effects is averaged - days)

IR = Ingestion Rate (kg/day)

EF = Exposure Frequency (days/year)

ED = Exposure Duration (years)

NNCO = Number of COCs with an Oral Chronic Reference Dose (unitless)

EQUATION 10: Risk management criteria calculation based upon the carcinogenic risks from

the ingestion of chemicals in fish tissue: residential, campground host, and

camper receptors

Where:

CF = Chemical Criteria in Fish (mg/kg)

TR = Target Excess Individual Lifetime Cancer Risk (unitless)

CAT = Carcinogenic Averaging Time (period over which exposure resulting in

carcinogenic effects is averaged - days)

CPSo = Oral Carcinogenic Potency Slope (mg/kg-day)- 1

EF = Exposure Frequency (days/year)

NCO = Number of COCs with an Oral Carcinogenic Potency Slope (unitless)

BWA = Body Weight, Adult (kg) BWC = Body Weight, Child (kg)

IRA = Ingestion Rate, Adult (kg/day)

IRC = Ingestion Rate, Child (kg/day)

EDA = Exposure Duration, Adult (years) EDC = Exposure Duration, Child (years)

CF (mg/kg) = THI RfD BW NCAT

IR EF ED NNCO

* * * o

* * *

BWA BWC +

IR ED A A * IR ED C C *

 CF (mg/kg) = TR CAT

CPS EF N o CO

* * * *
24

EQUATION 11: Risk management criteria calculation based upon ecological receptor

exposure to soil and plants

Where:

Cs = Dry Weight Soil Concentration

TRV = Toxicity Reference Value (mg/kg-day)

BW = Body Weight (kg)

IRS = Soil Ingestion Rate (g/day)

Br = Soil-Plant Uptake Factor (unitless)

IRp = Plant Ingestion Rate (g/day)

CF = Conversion Factor (kg/g)

PDW = Plant Fraction Dry:Fresh Weight (unitless: 0.65)

Variable Values:

TRV: chemical- and species-specific (See Table 3)

BW: species-specific

IRS: species-specific (Beyer, 1992)

Br: chemical-specific: arsenic .006; cadmium 0.14; copper 0.08;

lead .009; manganese .05; mercury 0.2; zinc 0.21

CF: 1E-03 kg/g

C (mg/kg) = S

TRV BW

IR CF S

*

* + B IR CF PDW r * * * p
25

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Final

U.S. Department of the Interior

Bureau of Land Management—National Science and Technology Center

P.O. Box 25047

Denver, CO 80225-0047

Dec. 1996, rev. Oct. 2004

BLM/RS/ST-97/001+1703

This report sets forth acceptable soil and sediment criteria for heavy metals released

from abandoned hard rock mining sites as they relate to ecosystem management and

protection of human health and wildlife. The USDI Bureau of Land Management

(BLM) manages approximately 270 million acres of public lands, primarily in the

Western U.S. These lands include several hundred thousand abandoned mining sites,

some of which may be releasing heavy metals into the environment at levels toxic to

wildlife.

26

Risk Management Criteria for Metals at BLM Mining Sites

Karl L. Ford, Ph.D.

• Mining

• Soils

• Wildlife

• Human health • Criteria

• Heavy metals

• Risk
26

Drawings by Janine J. Koselak

BLM, National Science and Technology Center