Golder Associates Inc.

200 Unio n Boulevard, Suite 500 Lakewood, CO USA 80228 Telephon e (303) 980-0540 F ax (303) 985-2080

375792

j'.'-Jli/Lyi'i * SURFACE WATER HUMAN HEALTH RISK ASSESSMENT

CALIFORNIA GULCH SITE pj [ £ LEADVILLE, COLORADO 3.07

Prepared For:

Asarco, Inc.

495 East 51st Avenue Denver, Colorado 80216-2098

Prepared By:

Golder Associates Inc.

200 Union Blvd., Suite 500 Lakewood, Colorado 80228

June 1996 943-2819

OFFICE S IN AUSTRALIA , CANADA , GERMANY , HUNGARY , ITALY , SWEDEN , UNITE D KINGDOM , UNITE D STATE S
June 1996____________________i____________________943-2819

TABLE OF CONTENTS

1.0 INTRODUCTION..................................................................................1

1.1 Objectives and Scope.............................................................................!

2.0 EXPOSURE ASSESSMENT......................................................................2

2.1 Potential Receptor Populations.................................................................2

2.2 Conceptual Site Model...........................................................................3

2.3 Complete Exposure Pathways.................................................................. 4

2.4 Estimating Chemical Intakes.................................................................... 4

2.5 Exposure Assumptions...........................................................................5

3.0 DATA ANALYSIS..................................:..............................................7

3.1 Chemicals of Concern ........................................................................... 7

4.0 TOXICITY ASSESSMENT....................................................................... 8

5 .0 RISK CHARACTERIZATION...................................................................9

5.1 Hazard Index for Noncarcinogenic Effects................................................. 10

5.2 Carcinogenic Risk .............................................................................. 12

5.4 Risk Characterization Results ................................................................ 14

6 .0 UNCERTAINTIES AND LIMITATIONS.................................................. . 15

6.1 Data Evaluation................................................................................. 16

6.2 Exposure Assessment.......................................................................... 16

6.3 Toxicity Assessment........................................................................... 17

6.4 Risk Characterization .......................................................................... 17

7.0 CONCLUSIONS.................................................................................. 17

8.0 REFERENCES.................................................................................... 18
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LIST OF TABLES

Table 1 Leadville Surface Water Potentially Complete Exposure Pathways Quantitatively Evaluated Table 2 General Assumptions for Body Weight Table 3 Intake Assumptions for Fish Ingestion Table 4 Leadville Surface Water Fish Tissue Data Summary Table and Exposure Point Concentrations Table 5 Lengths, Weights , and Age Classes of Trout Collected for Tissue Sample Analysis at Study Locations on the California Gulch Site In August, 1991 Table 6 Chronic and Subchronic Oral RfDs and Slope Factors for Chemicals of Concern Table 7 Surface Water Carcinogenic Risks and Noncarcinogenic Hazard Index (H.I.) Table 8 Summary of Uncertainty Factors in the Surface Water Baseline Risk Assessment

LIST OF FIGURES

Figure 1 Zinc Concentrations and Flow in California Gulch Figure 2 Predicted Zinc Concentrations in the Arkansas River Below California Gulch

LIST OF APPENDICES

Appendix A Interpretation Of ASSESS Output

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1.0 INTRODUCTION

T he followin g Human Health Risk Assessment (RA) for surface water has been prepared in

support of the Surface Water Remedial Investigation (RI) Report (Asarco, 1996a) to

evaluate potential health risks from metals in surface water in and around Leadville,

Colorado. Thi s RA was performed using data collected from the streams and rivers in and

near California Gulch site during the summer of 1991. The results presented in this RA

address potential health risks associated with surface water, specificall y the ingestion of

locally caught fish. All potential exposures from multiple sources will be evaluated

separately hi a sitewide baseline RA. The exposure parameters used in this RA may

change in the sitewide baseline RA. This RA evaluates only a single source contribution.

1.1 Objectives and Scope

The primary objective of this RA was to evaluate potential health risks due to exposure to

surface water using recently collected data. Where possible, site-specific data were used.

This approach is consistent with guidance provided by the EPA Risk Assessment Council

which stresses the use of site-specific data to evaluate potential health risks (EPA, 1992a,

b). Another objective of the RA was to follo w the Risk Assessment Council's guidance for

risk characterization limiting discussion of information to risk assessment, and not

including discussions of risk management. While the Reasonable Maximum Exposure

(RME) scenario used in this evaluation is designed to be a measure of "high-end" exposure

and is used by risk managers in making remedial decisions, the average or central tendency

risks information is necessary to make risk management decisions (EPA, 1992c).

Conservative assumptions were used only when site-specific data were lacking or

incomplete.

The scope of this RA was limited to the evaluation of potential health risks associated with

surface water historically affected by mining. The approach used was based on EPA

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guidance for the evaluation of human health risks at Superfund sites. This RA is consistent

with EPA guidance provided in the followin g documents: Exposure Factors Handbook

(EPA, 1989a), Risk Assessment Guidance for Superfund, Volume I: Human Health

Evaluation Manual (EPA, 1989b), and the Integrated Risk Information System (IRIS)

(EPA, 1992d), a computer database containing up-to-date health risk and regulatory

information for numerous chemicals. EPA cautions that these documents are intended to

provide only guidance in conducting health risk assessments, and that considerable

professional judgment must be used in their application (EPA, 1989b).

2 .0 EXPOSURE ASSESSMENT

The objective of this exposure assessment was to identify :

*• populations that may be exposed to surface water-related chemicals

(potential receptors);

*• pathways by which exposures may occur (conceptual site model);

*• the route of intake and intake parameter values for ingestion; and,

* the frequency, magnitude, and duration of these potential human

exposures.

2.1 Potential Receptor Populations

Populations in the Leadville area were evaluated to assess the likelihood and extent of

potential exposure to chemicals of concern. Populations that may be particularly sensitive

to chemical exposures include infants and children, the elderly, pregnant and nursing

women, and people with chronic illnesses. Sensitive receptor locations may include

hospitals, convalescent homes, schools, and day-care centers. Children are sensitive

receptor populations because they are not full y developed physically and their natural

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biochemical defenses may not be adequate for preventing or reducing adverse effect s due

to chemical exposures.

2.2 Conceptual Site Model

A Conceptual Site Model (CSM), showing all potentially complete exposure pathways for a

source is presented in Figure 1. Significant exposure pathways are represented with a

solid circle; an open circle represents those pathways considered to be insignificant relative

to other exposure pathways. EPA guidance defines an insignificant pathway as one that

has an exposure estimated to be two or more orders of magnitude less than by other

pathways (of the same receptor), or one with a very small likelihood of exposure by that

pathway (EPA, 1989b).

Ingestion of sediment by the chosen receptors was considered highly unlikely, and was

considered an incomplete pathway. Exposure pathways associated with groundwater and

vegetable ingestion are labeled as "not evaluated" on the CSM because these media will be

considered in another RA as part of the Hydrogeologic RI Report (Asarco, 1996b).

Swimming, wading, and surface water ingestion are considered unlikely due to the

temperatures of the surface waters. For this reason, and the fact that metals are not

absorbed well across the skin, dermal contact with surface water was not considered a

significant exposure pathway (EPA, 1991a). Although recreational users, such as kayakers

may occasionally ingest surface water, the short-term nature of these exposures would

constitute insignificant risk.

Human Receptors

Based on the evaluation of potentially complete pathways, the human receptors associated

with the exposure points selected are:

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+ Adult Recreational User

» Child

The Adult Recreational User and Child were selected to represent people who might

routinely fish in the streams and rivers near the California Gulch and who may eat fish.

2.3 Complete Exposure Pathways

The final component of a complete exposure pathway is an intake route into the body.

Table 1 summarizes the pathways that were evaluated in this RA. As shown in the CSM

(Figure 1), the only complete exposure pathway considered quantitatively for this RA was

ingestion of fish. This exposure will be evaluated for the two receptors: the Adul t

Recreational User, and the Child.

2.4 Estimating Chemical Intakes

The next step in the exposure assessment was to quantify the magnitude, frequency, and

duration of chemical intakes by receptor populations. This step was conducted in two

stages: (1) estimation of exposure point concentrations, and (2) estimation of chemical

intake for each exposure pathway under consideration. Chemical intakes were calculated

using guidance in Risk Assessment Guidance for Superfun d (EPA, 1989b), Exposure

Factors Handbook (EPA, 1989c), Assessing Human Health Risks from Chemically

Contaminated Fish and Shellfish (EPA, 1989d), other EPA documents and scientific

journal articles, site-specific information, and professional judgment regarding likely

exposure conditions. Chemical intakes were estimated using average and RME estimates

of chemical concentrations in fish fillets , reasonable estimates of exposure parameters such

as body weight, ingestion rates, and other assumptions regarding frequency and duration of

exposure. The intake factors used to quantify chemical intakes are presented in the Surface

Water RI Report (Asarco, 1996a).

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Exposure point concentrations used to calculate potential risks from the ingestion of fish

were obtained by calculating the average and 95 percent upper confidence limit (UCL) on

the mean for each chemical of concern from available analytical data from recent site

investigations. Data collection and analysis are described in the Surface Water RI Report

(Asarco, 1996a).

2.5 Exposure Assumptions

The extent of potential intake through the various exposure pathways was based on EPA

guidance, site-specific information, and professional judgment. It is not possible to

estimate the exact level of exposure for specific individuals due to uncertainties in behavior

patterns and incomplete knowledge of exposure variable values. A primary objective of

this RA was to use site-specific data where possible in order to not underestimate potential

human exposures.

Children were identified as a sensitive receptor population in Leadville. Therefore,

exposure variables were calculated incorporating youth as a factor. Because certain

exposure parameters vary over tune (e.g., ingestion rates, body weights), time-weighted

average body weights were calculated for the Adul t Recreational User and the Child

receptors (Table 2).

The data used to determine the exposure frequency were taken from the Metals Samplin g

and Analysis Results and Demographics Results (Asarco, 1992). The survey results

indicated that the majority (65.2 percent) of children in Leadville never eat locally caught

fish. Another 24.3 percent eat locally caught fish less than once per month. Therefore,

for an average exposure for children, a frequency of six locally caught fish meals per year

was used for the RA. The survey results also indicated that only 2.8 percent of the

children eat locally caught fish two or more times per week. For a RME scenario for

children, a frequency of one locally caught fish meal per week was used and was

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considered conservative in light of the survey results. Thi s number represents the

inclusion of the 97th percentile of all respondents.

For adults, the survey indicated that 71 persons, or approximately 4 percent of

respondents, eat locally caught fish more frequently than twice per week. Based on this

result, a frequency of three fish meals per week was used for the RME scenario. The

survey results also indicated that approximately 50 percent of respondents do not eat

locally caught fish and that 30 percent eat locally caught fish less than once per month.

For this RA, a frequency of one locally caught fish meal per week was used for average

exposures.

The ingestion rate for adults was assumed to be 150 grams (1/3 of a pound) per meal

(EPA, 1989d). In the Exposure Factors Handbook (EPA, 1989a), a study conducted by N PD Research, Inc. presents total fish consumption by age range. To determine ingestion

rates for children, a weighted average was used to convert the age ranges presented in the

study to those used in this RA. From these data, for both the mean and upper 95th

percentile, the weight of fish consumption by children (0 to 6 years of age) was found to

be 54 percent of that consumed by adults (7 to 30 years of age). Thi s factor was applied to

the ingestion rate for adults to derive a fish ingestion rate of 81 grams per meal for

children.

For carcinogenic ingestion exposure durations, it was assumed that the Adult Recreational

User would be exposed for 3 years for the average scenario and 24 years for the RME

scenario. The assumption was made that the child receptor would be exposed 6 years for

both the average and RME scenarios. Addition of these exposure durations for the average

scenario equals nine years (6 years for children and 3 years for the adult), and equals thirty

years for the RME scenario (6 years for children and 24 years for the adult). These

durations relate to the national median and upper bound estimates of 9 and 30 years,

respectively, spent in one residence (EPA, 1989b).

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The equation and specific variables used to estimate intake of chemicals via fish ingestion

are summarized in Table 3. Intake factor calculations are documented in Appendix A.

3 .0 DATA ANALYSIS

An early step of the RA was to review recent water quality chemical data collected at the

site. The objective of data analysis was to identify chemicals of concern in surface water.

Only validated data used in the quantitative evaluation of risks.

In order to quantify average and RME concentrations, a value of one half the detection

limit was used when the sample was reported as undetected. This is consistent with EPA

guidance (EPA, 1989b) and the Surface Water, Bed Material and Aquatic Ecosystem Data

Collection Program Work Plan (Asarco, 1991). Average analyte concentrations were used

in the calculations of risk for average exposure, and the 95 percent upper confidence limits

(UCL) of the arithmetic mean analyte concentrations were used in the calculations of the

RME scenario. Fish tissue data are presented in Table 4.

3.1 Chemicals of Concern

Analytical data were obtained as part of the Surface Water, Bed Material and Aquatic

Ecosystem Data Collection Program Work Plan (Asarco, 1991) and were evaluated to

identify chemicals of concern. The data for this program were collected in the summer of

1991. Fish caught in the program were filleted, and only the edible portions of the fish

were analyzed. Fish tissue analyses were limited to the followin g metals: arsenic,

cadmium, chromium, copper, lead, mercury and zinc; the locations of the sampling

stations for the collection of fish are shown hi Figure 4.1 of Asarco, 1991. Fish caught

were representative of the predominant species found in the area. Table 5 shows the type,

size, and approximate age of the fish sampled according to location. (Aquatics Assoc.,

1993).

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Chemicals of concern for surface water were selected from the metals detected in the fish

tissue. Cadmium was not detected in any of the sampled fish tissue. Six metals were

quantitatively evaluated for potential noncarcinogenic hazards and carcinogenic risks.

Because the final number of chemicals of concern was low, it was considered unnecessary

to perform a concentration-toxicity screen. The chemicals of concern were arsenic,

chromium, copper, lead, mercury, and zinc.

Lead was not quantitatively evaluated in this surface water RA. The potential health

impacts from the exposure to lead will be quantified in a site wide, multi-media, baseline

risk assessment using the most current EPA Integrated Exposure Uptake-Biokinetic

(IEUBK) lead model available. This model accounts for lead exposure from many sources

and predicts blood lead levels with the input of either EPA defaul t values, site-specific

values, or a combination of both.

4 .0 TOXICITY ASSESSMENT

Thi s section describes procedure involved in performing the toxicity assessment for

chemicals of concern in surface water at the Leadville site.

The purpose of the toxicity assessment was to evaluate the toxicity of chemicals of concern

and to estimate the dose-response relationship for each of these chemicals. Chemicals of

concern in Leadville were identified by the application of EPA guidance and professional

judgment. The information obtained in the toxicity assessment was combined with

estimated contaminant intakes calculated as part of the exposure assessment to estimate the

potential excess lifetime cancer risks and potential noncarcinogenic health hazards (EPA,

1989b).

T he Reference Dose (RfD) and Slope Factor (SF) values used in this risk assessment were

obtained from the folio whig sources:

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>• EPA's Integrated Risk Information System (IRIS) (EPA, 1992d) on-line

database system; and,

* EPA's Health Effect s Assessment Summary Tables (EPA, 1992e).

Chemicals with high SFs and low RfDs exhibit higher toxicities. Table 6 summarizes

toxicity values used in this risk assessment for the chemical of concern.

5 .0 RISK CHARACTERIZATION

Risk characterization was the final step of the risk assessment process. In this step, the

toxicity factors (RfDs and SFs) for the chemicals of concern were applied hi conjunction

with estimated chemical intakes to predict noncarcinogenic and carcinogenic health risks to

exposed individuals.

T he potential for noncarcinogenic effect s was characterized by comparing estimated

chemical intakes with chemical-specific RfDs. This measure is known as the hazard

quotient (H.Q.) for a single chemical or the hazard index (H.I.) for multiple chemicals.

Potential carcinogenic effect s are characterized in terms of the incremental or excess

probability that an individual will develop cancer hi his or her lifetime due to the modeled

exposure. Excess cancer risk is estimated from the projected lifetime intakes and the

cancer slope factor, which represents an upper-bound estimate of the dose-response

relationship.

In this RA, subchronic (2 weeks to 7 years) H.I.s are the appropriate indicator of potential

non-cancer adverse effect s for the average child exposure (6 years), the RME child

exposure (6 years), and the average Adult Recreational User exposure (3 years). The

chronic H.I. is the appropriate indicator for the RME Adul t Recreational User because the

exposure duration is 24 years (which is greater than the 7 year cutoff between subchronic

and chronic timespans). However, when the child and adult scenarios are summed to

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represent continuous exposure of one individual over both age groups (i.e., birth through 9

years for average, or birth through 30 years for RME), the chronic H.I.s are summed as

the appropriate indicators of non-cancer risk for timespans exceeding 7 years.

5 .1 Hazard Index for Noncarcinogenic Effect s

The potential for adverse noncarcinogenic effect s resulting from exposure to a chemical of

concern was evaluated by comparing the average daily intake of the chemical (expressed as

mg/kg-day) to a reference dose (expressed as mg/kg-day). The resulting ratio is called a

H.Q. (EPA, 1989b). The H.Q. was calculated as:

TT Noncance __ Chemical Intake (mg/ kg-day) r H.Q. = —————————-—-—— — R fD (mg/kg-day )

Use of the RfD assumes a level of intake (the RfD) below which it is unlikely that even

sensitive individuals will experience adverse health effect s over a lifetime of exposure. If the

average daily intake exceeds the RfD (that is, if the H.Q. exceeds 1.0), there may be cause

for concern for potential noncancer effects . It should be noted, however, that the level of

concern does not increase linearly as the RfD is approached or exceeded. This is because all

RfDs are not equally accurate and are not based on the same severity of toxic effects . Thus ,

the slopes of the dose-response curve hi excess of the RfD can vary widely depending on the

substance. Furthermore, it must be emphasized that the H.Q. does not represent a statistical

probability of an effect occurring.

To assess the overall potential for adverse health effect s posed by exposure to multiple

chemicals, the H.Q.s for each chemical of concern associated with a given exposure pathway

were summed. The resulting sum is referred to by EPA as the H.I. The H.I. approach

assumes that multiple subthreshold exposures to several chemicals could result in an adverse

health effect . The H.I. was calculated as:

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H.I. = E 1/RfD 1 + E2/RFD2 ... + E/RfDj

where:

Ej = Exposure level (or intake) for toxicant i

RfDj = Reference dose for toxicant i

Where a receptor may be subject to multiple exposure pathways (e.g., inhalation of

particulates and ingestion of soils), the individual H.I. s from all relevant pathways are

summed to obtain the total H.I. for that receptor. For multiple chemical exposures, the total

H.I. might exceed 1.0 even if no single chemical intake exceeds its RfD. If the total H.I. is

less than 1.0, cumulative exposures to the chemicals of concern at the site is judged unlikely

to result in an adverse effect . If the sum is greater than 1.0, a more detailed and critical

evaluation of the risks, including consideration of specific target organs affected and

mechanisms of toxic action of the chemicals of concern, is required to ascertain if the

cumulative exposure would in fact be likely to harm exposed individuals.

T he assumption of additive effect s reflected in the cumulative H.I. is most properly applied

to substances that induce the same effec t by the same mechanism (EPA, 1989b).

Consequently, application of the equation to a mixture of substances that are not expected to

induce the same type of effect s could overestimate the potential for adverse health effects . The H.I. provides a rough measure of potential toxicity, but it is conservative and dependent

on the quality of the experimental evidence. Since the H.I. does not define dose-response

relationships, its numerical value cannot be construed as a direct estimate of risk (EPA,

1989b), but only as a level of concern.

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5.2 Carcinogenic Risk

Carcinogenic risks are estimated as the incremental probability of an individual developing

cancer over a lifetime as a result of exposure to a potential carcinogen. The numerical

estimate of excess lifetime cancer risk is calculated by multiplying the chemical intake

averaged over a lifetime by the cancer slope factor (SF) as follows:

Risk = Chemical Intake (mg/kg-day) x SF (mg/kg-day)"1

The EPA slope factors are upper 95th percentile confidence limits of the probability of

response per unit intake of chemical over a lifetime. Slope factors are based on experimental

animal data and epidemiological studies when available. The linearized multistage model, a

linear nonthreshold mathematical model for low-dose extrapolation, is used to calculate a

numerical slope factor value. EPA states that carcinogenic risks estimated using this

approach are upper-bound estimates. This means that the actual risk is likely to be less than

the predicted risk (EPA, 1989b).

EPA guidance to evaluate cancer risk from simultaneous exposure to several carcinogens

assumes that incremental cancer risks are additive. The concept that cancer risks are additive

is based on a number of assumptions. If these assumptions are incorrect, over- or underestimation of the actual risk could result (EPA, 1989b). The total cancer risk is estimated by

summing the risks estimated for each chemical of concern and for each pathway.

EPA policy must be considered in order to interpret the significance of the cancer risk

estimates. In the National Oil and Hazardous Substances Pollution Contingency Plan (NCP)

(40 CFR Part 300), EPA states that: "For known or suspected carcinogens, acceptable

exposure levels are generally concentration levels that represent an excess upper-bound

lifetime cancer risk to an individual of between 10^ and 10"6." The EPA further states, in

the preamble to the NCP , that the 1 x 10"6 risk level should be used as a point of departure

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for establishing remediation goals for contaminants at specific hazardous waste sites. Current

EPA guidance, however, states that where the cumulative site risk to an individual based on

reasonable maximum exposure is less than 1 x 10"4, action is generally not warranted (EPA,

1991b). A carcinogenic risk level of 1 x 10^ was therefore used as the target risk level for

evaluation of potential exposures in this risk assessment.

Risk Quantification

The potential for noncarcinogenic health effect s due to a chemical of concern, expressed as a

H.Q. , is calculated using the followin g format:

( Chemical Intake Daily ) / RfD Hazard Concentration X Factor = Intake (mg/kg-day) = Quotient

(mg/y) (y/kg- (mg/kgday) day)

Where y = specific amount (weight or volume) of medium hi which the chemical is

measured; the units of which are medium dependent. For example, a

chemical in soil may be reported hi mg/kg and hi water in mg/liter.

Average or RME concentrations of each noncarcinogenic chemical of concern are multiplied

by the pathway-specific intake factors to yield an average or RME daily intake. The daily

intake is then divided by the RfD to obtain the H.Q. for average or reasonable maximum

exposures.

Individual H.Q.s are summed for all chemicals in an exposure pathway to provide a pathwayspecific H.I. Pathway-specific indexes are summed to obtain the total H.I. for all exposure

pathways applicable to a given receptor.

H.I.s of noncarcinogenic risks for each receptor and pathway are summarized in the Surface

Water RI Report (Asarco, 1996a). H.I.s are calculated for chronic exposures (9 or 30 years)

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for receptors at each of the exposure locations. Risk calculations are presented in Appendix

A.

The potential for carcinogenic effects , expressed as excess cancer risk, are calculated in a

similar manner:

( Chemical Lifetime Lifetime ) Slope Factor Excess

Concentration X Intake = Daily X (mg/kg-day)"1 = Cancer

(mg/y) Factor Intake Risk

(y/kg-day) (mg/kgday)

Where y = specific amount (weight or volume) of a medium in which the chemical is

measured; the units of which are medium dependent.

Concentrations of each potential carcinogen are multiplied by pathway-specific intake factors

to yield a lifetime daily intake. The daily intake is then multiplied by the slope factor to

obtain a numerical estimate of excess cancer risk.

The cancer risks are then summed for all of the chemicals evaluated for each exposure

pathway. To determine the total carcinogenic risk to a given receptor, the cancer risks for

each exposure pathway are summed. Carcinogenic risks for average and RME conditions are

presented in Table 7. Cancer risk calculations are shown in Appendix A.

5.4 Risk Characterization Results

Results of this RA indicate that no noncarcinogenic H.I.s exceeded the EPA level of concern

of 1.0 for the exposure pathway evaluated for surface water using average or reasonable

maximum exposure assumptions (Table 7).

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F or surface water, the greatest H.I. for a receptor for average exposure assumptions was

3.58 x 10"1 and represents the Adult Recreational User. The greatest H.I. for RME

assumptions for surface water was also for the Adult Recreational User (5.98 x 10"1).

Summing the chronic H.I.s across the ages of birth to 30 years for RME and from birth to 9

years for average exposure resulted in a combined H.I. less than 1.0. For average exposures

the chronic H.I. sum was 3.93 x 10"1, and for RME assumptions the chronic H.I.s sum was

9.82 x 10"1. EPA human health risk assessment guidance states that if a H.I. greater than 1.0

is obtained as a result of summing several H.Q.'s, then it is appropriate to segregate

compounds by effect and by mechanism of action, and to derive separate H.I.s for each effect

on specific target organs or mechanisms of action (EPA, 1989b). Based on the exposure

assumptions used, this was unnecessary.

No estimated carcinogenic risks exceeded the EPA acceptable risk level of 1 x 10"4 for the

exposure pathway (fish ingestion) evaluated for both receptors considered. Total carcinogenic

risk estimated for the Child and Adult Recreational User, adding across the ages of birth to

30 years of age, for the RME scenario was 3.13 x 10"5 (Table 5). For the average scenario,

the total carcinogenic risk was 2.29 x 10"6. The RME scenario for total cancer risks across

the ages from birth to 30 years is used as the "high-end" exposure (EPA, 1992f). The

average exposure scenario shown in Table 7 describes central tendency exposure risks to aid

in discussion of uncertainties and to put the RME scenario into perspective. In the RME case

for surface water, the risks from ingestion of fish did not exceed 1 x 10"4 for either receptor.

6 .0 UNCERTAINTIES AND LIMITATIONS

The EPA guidance for risk assessment provides a systematic means for organizing,

analyzing, and presenting information on the nature and magnitude of potential risks to public

health and the environment posed by chemical exposures. Despite the advanced state of the

current methodology, uncertainties and limitations are inherent in the risk assessment

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process. The quality of available data, incomplete information about existing conditions and

future circumstances, as well as other factors discussed below contribute to these

uncertainties and limitations. The following sections discuss sources of uncertainties and

limitations associated with this risk assessment. These uncertainties are also summarized hi

Table 8.

6.1 Data Evaluation

Data used hi the RA were collected during the Surface Water, Bed Material and Aquatic

Ecosystem Data Collection Program for the California Gulch Site study area. The data

collected during the program are subject to uncertainty associated with sampling and analysis,

and this may act to over- or under-estimate the potential risks.

6.2 Exposure Assessment

The exposure assessment is based on site-specific data and on a series of assumptions

concerning concentrations of chemicals to which humans may be exposed (exposure point

concentrations) as well as patterns of behavior leading to exposure or intake of chemicals

(exposure scenarios).

The exposure assessment relied on assumptions for potential human exposure when sitespecific analytical data were incomplete or unavailable. Assumptions used were based upon:

* Site-specific information

+ EPA Guidance (EPA 1989b) and the Exposure Factors Handbook (EPA 1989a)

*• Professional judgment

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6.3 Toxicity Assessment

In general, the available scientific information is insufficient to provide a thorough

understanding of all the potential toxic properties of chemicals to which humans are

potentially exposed. Consequently, varying degrees of uncertainty surround the

assessment of adverse health effect s in exposed populations.

6.4 Risk Characterization

Due to uncertainties hi each step of the risk assessment process, uncertainties are often

magnified in the final risk characterization. The final quantitative estimates of risk may be

one or several orders of magnitude differen t from the potential risk associated with a given

exposure. In an attempt to minimize the consequences of uncertainty, EPA guidance

typically relies on use of conservative estimates of hazards in the absence of strong

scientific data. The overall result is that risk estimates presented in this report are much

more likely to overestimate the potential risk rather than to underestimate it.

The assessment has been prepared in a manner consistent with that generally used in the

consulting community and agency guidance at the tune it was prepared. It is likely that

risk assessment methods and data identifying and quantifying the toxicity of chemicals will

improve with time. Thi s assessment was based on recently collected data using the current

available risk assessment methodology.

7.0 CONCLUSIONS

The results of this risk assessment indicate that for human exposure to metals hi fish fillets ,

the noncarcinogenic H.I. s do not exceed the EPA level of concern of 1.0. Estimated

carcinogenic risks do not exceed the EPA acceptable risk level of 1 x 10"4 for the exposure

pathway evaluated for any receptors (Table 7). Additionally , potential total cancer risks from

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birth to age 30 were 2.29 x 10"6 (average scenario) and 3.13 x 10"5 (RME scenario) and do

not exceed 1 x 10"4 for exposure to surface water (fish ingestion) (Table 7). It should be

restated that the RME scenario in this risk assessment used a combination of site-specific data

and conservative assumptions that represent the "high-end" exposure and more than likely

overestimates the actual total cancer risk given the exposure and behavior patterns assumed

f or this assessment.

It seems unlikely that any individual will consume locally caught fish one time per week

every week of the year from birth to 6 years of age and three times per week thereafter

through age 30. In addition, it is unlikely that any individual will be exposed as a child and

as an adult over a period of 30 years. Adding the risks for these receptors, therefore,

presents very conservative estimates of risk. Even using this very conservative (protective)

approach, potential cancer and non-cancer risks to humans who consume fish affected by

site-related chemicals are below EPA benchmark levels. Fish ingestion is the only (complete

or significant) exposure pathway for surface water at the California Gulch Site.

8.0 REFERENCES

Aquatics Associates. 1993. Aquatic Sampling Program Results California Gulch Site. Leadville, Colorado, 1991. January.

Asarco. 1991. Surface Water, Bed Material and Aquatic Ecosystem Data Collection Program Work Plan, California Gulch Site, Leadville, Colorado. Prepared by Woodward-Clyde Consultants. June. Asarco. 1992. Metals Samplin g and Analysis Results and Demographics Results. Transmittal letter to Ken Wangerud from Glenn Anderson on September 15.

Asarco. 1996a. Surface Water Remedial Investigation Report. Prepared by Golder Associates Inc. May.

Asarco. 1996b. Hydrogeologic Remedial Investigation Report. Prepared by Golder Associates Inc. May.

Golder Associates
June 1996___________________19____________________943-2819

U.S. Environmental Protection Agency (EPA). 1989a. Exposure Factors Handbook.

Exposure Assessment Group Office of Health and Environmental Assessment. Washington, D.C. EPA/600/8-89/043.

U.S. Environmental Protection Agency (EPA). 1989b. Risk Assessment Guidance for Superfund. Volume I: Human Health Evaluation Manual. Interim Final. Office of Emergency and Remedial Response EPA/600/8-89-/043.

U. S. Environmental Protection Agency (EPA). 1989c. Phase II Remedial Investigation, Technical Memorandum. Draft. California Gulch, Leadville, Colorado. Vols. I-VI.

53-8129.0/DEN63786.RI. Prepared by CH2M Hill, Black & Veatch, ICF, PRC, and

Ecology and Environment. May.

U.S. Environmental Protection Agency (EPA). 1989d. Assessing Human Health Risks from Chemically Contaminated Fish and Shellfish: A Guidance Manual.

U.S. Environmental Protection Agency (EPA). 1991a. Preliminary Human Health Baseline Risk Assessment for the California Gulch NPL Site, Leadville, Colorado. Prepared

f or the U.S . EPA Region VHI, Denver, Colorado by Roy F. Weston, Inc., Lakewood, Colorado.

U.S. Environmental Protection Agency (EPA). 1991b. Risk Assessment Guidance foi Superfund: Volume I - Human Health Evaluation Manual (Part B, Development of Risk-based Preliminary Remediation Goals). Interim. 9285.7-0IB.

U.S. Environmental Protection Agency (EPA). 1992a. Guidelines for Exposure Assessment. 57 FR 22888-22938, May 29, 1992.

U.S. Environmental Protection Agency (EPA). 1992b. Memo from F. Henry Habicht, Deputy Administrator, EPA. Guidance on Risk Characterization for Risk Managers

and Risk Assessors. February 26, 1992.

U.S. Environmental Protection Agency (EPA). 1992c. Memo from Henry L. Longest, Director, Office of Emergency and Remedial Response. Implementing the Deputy Administrator' s Risk Characterization Memorandum. May. U.S. Environmental Protection Agency (EPA). 1992d. Integrated Risk Information System

(IRIS). On-line database.

U.S. Environmental Protection Agency (EPA). 1992e. Health Effect s Assessment Summary Tables (HEAST). Annual FY-1992. OHEA-ECAO-CIN-821. March.

Golder Associates
Golder Associates
TABLE 1

LEADVILLE SURFACE WATER

POTENTIALLY COMPLETE EXPOSURE PATHWAY S QUANTITATIVELY EVALUATED

Potentially Exposed Receptor Scenario Potentially Complete Exposure Pathways

Child Current Fish ingestion

Adult Recreational User Current Fish ingestion

Source: Woodward Clyde Consultants, Draft Surface Water RI Report

Colder Associates
a

TABLE 2 GENERAL ASSUMPTIONS FOR BODY WEIGHT

Age Range

0-3

3-6

6-9

9-12

12-15

15-18

18-30

Years in Age Range

3

3

3

3

3

3

12

K ga

11.6

17.4

25.0

36.0

50.6

61.2

70

TIME WEIGHTED AVERAGE BODY WEIGHTS

Child (1-6 years)"

Adult (7-30 years)c

Years in Age Range

6

3/24

Body Weight

16

25/57

Exposure Factors Handbook (EPA 1989a).

b

 RAGS (EPA 1989b). Represents the 50th percentile body weights for children ages 1 to

6 years (not a true weighted average).

c

 Average scenario used 7 to 9 years of age and RME scenario used 7 to 30 years of age.

Source: Woodward Clyde Consultants, Draft Surface Water RI Report

Colder Associates
TABLE 3 INTAKE ASSUMPTIONS FOR FISH INGESTION

Intake Factor = IR x EF x ED x FI x ME x IQ^g/mg BWxA T

Parameter Average Reasonable Maximum

IR = Ingestion rate, mg/day1

Adult (> 6) 150,000 150,000

Child (0-6 years) 81,000 81,000

EF = Exposure frequency, days/years2

Adult 2 156 Child 6 52

ED = Exposure duration, years

3

Adult 3 24 Child 6 6 ME = Matrix effect 4

 1.0 1.0 FI = Fraction ingested from

contaminated source 1.0 1.0 BW = Body weight, kg5

Adult (weighted average) 25 57 Child (weighted average) 16 16 AT = Averaging time, days6

Noncarcinogens Adul t 1,095 (3 years) 8,760 (24 years) Child 2,190 (6 years) 2,190 (6 years) Carcinogens 25,550 (70 years) 25,550 (70 years)

1

 EPA, 1989a and EPA.O 1989c. (See text for farther explanation, Section 7.5.2). 2

 1 fish meal/week for adult average exposure, 3 fish meals/week for adult RME scenario. 6 fish meals/year for child average

3 exposure, 1 fish meal/week for child RME scenario. (Asarco 1992)

 See text, Section 7.5.2 for explanation. 4

 Matrix effec t of 1.0 represents a conservative assumption about the amount of metals that are bound to the medium' s matrix. The

higher the ME, the greater amount of metals are potentially bioavailable. ME of one assumes all metals are 100 percent

bioavailable and absorbed. 5

 EPA, 1989a. 6

 Nin e years (6 years as a child and 3 years as an adult) and 30 years (6 years as a child and 24 years as an adult) are years spent in

one residence for the national median and upper bound estimates, respectively (EPA 1989b). Averaging time is the product of

these time periods and days per year. (See text, Section 7.5.4 for further explanation.)

Source: Woodward Clyde Consultants, Draft Surface Water RI Report

Colder Associates
TABLE 4 LEADVILLE SURFACE WATER FISH TISSU E DATA SUMMARY TABLE AND EXPOSURE POINT CONCENTRATIONS

(mg/kg) a

•$:^§^mii§£§::.

A-AR01F-01-910813

A-AR02F-01-910813

A-AR03F-01-910813

A-AR04F-01-910814

A-AR05F-01-910814

A-EF01F-01-910812

A-EF02F-01-910812

A-EF02F-01-910815

A-EM02F-01-910814

A-EM03F-01-910814

A-EM04F-01-910814

A-HC01F-01-910813

A-IC501F-01-910813

A-LF01F-01-910813

A-TC01F-O1-910814

Number of Records Number Detects Minimum Median Maximum Average

95% UCL

Standard Deviation

Student 0.05

SEM"

: Arsenic:

0.1

0.02

0.01

0.01

0.01

0.02

0.02

0.06

0.02

0.02

0.01

0.02

0.01

0.04

0.01

15

9

0.02

0.02

0.10

0.03

0.04

0.02

1.761

0.01

: :;;/PL.: :: :

; : :: :::Qual.

:

: ; ;: J

J

0.02 UJ

0.02 UJ

0.02 UJ

J

J

J

J

J

0.02 UJ

J

0.02 UJ

J

0.02 UJ

• '. Chromium • .

 :

 :.

:

 :

:

x

:

 ::

 Si Result; V V <.; DL y-

:

-v Qua!: : .-.. .•:•• : '• : '•::•.•:•.-.•. • .• : • • • :••••. • • • — '••/ . -..

:

.-

0.4

0.3

0.3

0.4

0.2

0.2

0.2

0.3

0.3

0.3

0.2

0.4

0.3

0.4

0.05 0.1 U

15

14

0.20

0.30

0.40

0.28

0.33

0.10

1.761

0.03

- /Copper "-.&:- '•'••::•• •

P$l^;||£fP

0.6

0.4

0.5

0.2

0.3

0.3

0.4

0.4

0.4

0.3

0.4

0.4

0.4

0.4

0.3

15

15

0.20

0.40

0.60

0.38

0.42

0.09

1.761

0.02

L

:g :

:

:- K:

:

:Qioal.:::::

:::::

:;::

 ^Result;:::;?:;:;:^:';:^

 :

:

:

;

: J 0.2

J 0.2

J 0.2

J 0.2

J 0.4

J 0.2

J 0.2

J 0.2

J 0.2

J 0.2

J 0.2

J 0.2

J 0.2

J 0.2

J 0.2

15

15

0.20

0.20

0.40

0.21

0.24

0.05

1.761

0.01

j-v"--::;- : , :-;

:

 ' , ^••^iff^.;^-^^^^

0.09

0.12

0.01 0.02 U

0.2

0.01 0.02 U

0.04

0.05

0.08

0.04

0.03

0.1

0.07

0.01 0.02 U

0.04

0.11

15

12

0.03

0.08

0.20

0.07

0.09

0.05

1.761

0.01

^':3^^/&---:-^.&-~Jf*-

5.9

8

8.9

3.5

5.8

4.7

4.8

9.3

5.5

4.5

3.9

4

5.1

5.3

5.1

15

15

3.50

5.10

9.30

5.62

6.42

1.76

1.761

0.46

" Average and 95th UCL concentrations used for average and RME scenarios respectively. Standard error of the mean. DL = Detection Limi t U = Not Detected J = Estimated SOURCE : WOODWAR D CLYD E CONSULTANTS , DRAF T SURFAC E WATE R R I REPORT

Golder Associates
TABLES

LENGTHS, WEIGHTS, AND AGE CLASSES OF TROUT

COLLECTED FOR TISSUE SAMPLE ANALYSIS AT STUDY LOCATIONS

ON THE CALIFORNIA GULCH SITE IN AUGUST, 1991

a

Location

East Fork Arkansas River

EF-1

EF-2

Arkansas River

AR-1

AR-2

AR-3

AR-4

AR-5

Tennessee Creek

TC-I

Lake Fork

LF-1

Halfmoon Creek

HC-1

Iowa Gulch

IG-1

Sample No.

A-EF01F-01-910812 A-EF01F-01-910812

A-EF02F-01-910812 A-EF02F-01-910812 A-EF02F-01-910815

A-AR01F-01-910813 A-AR01F-01-910813

A-AR02F-01-910813 A-AR02F-01-910813

A-AR03F-01-910813 A-AR03F-01-910813

A-AR04F-01-910814 A-AR04F-01-910814

A-AR05F-01-910814 A-AR05F-01-910814

A-TC01F-01-910814 A-TC01F-01-910814

A-LF01F-01-910813 A-LF01F-01-910813

A-HC01F-01-910813 A-HC01F-01-910813

A-IG01F-01-910813 A-IG01F-01-910813

Species

Brownb

Brown

Brown Brown Brown

Brown Brown

Brown Brown

Brown Brown

Brown Brown

Brown Brown

Brown Brown

Brown Brown

Brown Brown

Brookd

Brook

Length

(mm)

220

255

274

240

332

295

265

235

200

180

129

401

264

340

230

280

304

406

271

250

280

213

201

Weight

( g)

115

175

215

155

355

180

175

75

75

65

25

610

215

435

135

210

265

650

197

170

200

120

95

A ge Class

c

5 +

—

2+

2+

1 +

3 +

4+

2+

—

3+

5+

3 +

2+

Colder Associates
TABLES

(Concluded)

Location

Empire Gulch

EM-2

EM-3

EM-4

Sample No.

A-EM02F-01-910814 A-EM02F-01-910814

A-EM03F-01-910814 A-EM03F-01-910814

A-EM04F-01-910814 A-EM04F-01-910814

Species

Brook Brook

Brown Brown

Brook Brook

Length

(mm)

212

212

222

246

231

197

Weight

( g)

120

120

110

125

120

80

A ge Class

—

.

-

4 +

3 +

a

 Fillet s were combined for digestion and metals analysis at each site, except at site EF-2 where fillet s from the two

smaller fish were combined, and the fillet from the largest fish was,analyzed separately.

b

 Salmon trutta c

 Age class could not be determined since the scale sample was regenerated and not readable.

d

 Salvelinus fontinalis

SOURCE: WOODWARD CLYDE CONSULTANTS, DRAFT SURFACE WATER RI REPORT

Colder Associates
TABLE 6 CHRONIC AND SUBCHRONIC ORAL RfDs AND SLOPE FACTORS FOR CHEMICALS OF CONCERN

Toxicity

Compound

Arsenic

Chromium VI

Copper

Lead

Manganese

Silver

Zinc

Sources: (EPA, 1992d, EPA,

a

 Value from Health Effect s

b

C

 Verified, available on IRIS

 \Tr*.~lfi<*A mrn:1nV>1a r\n TT>T C

Exposure Route

Ingestion

Ingestion

Ingestion

Ingestion

Ingestion

Ingestion

Ingestion

Subchronic R fD

(mg/kg-day)

3E-04a

2E-02a

3.7E-02d

ND

N Df

5E-03a

2E-01a

Chronic R fD

(mg/kg-day)

3E-04C

5E-03b

3.7E-02"

N De

N Df

5E-03b

3E-01b

1992e)

Assessment Summary Tables (HEAST), March 1992.

Carcinogenicity

Slope Factor

(mg/kg-day)"1

1.75

d

ND

ND

ND

ND

ND

ND

EPA Weight

of Evidence

Category8

A

ND

D

B2

D

D

D

Value from HEAST, March 1992. Converted from Drinking Water Standard to RfD (mg/kg-day). e

 Oral RfD not verified and currently not under discussion. The EPA IEUBK model will be used in the sitewide Baseline RA to evaluate oral exposures to lead. f

 Withdrawn from IRIS 10-01-92.

8

 A = Human carcinogen B2 = Probable human carcinogen D = Not classifiable as to human carcinogenicity

(EPA, 1989b) ND = Not determined by EPA

SOURCE: WOODWARD CLYDE CONSULTANTS, DRAFT SURFACE WATER RI REPORT

Golder Associates
TABLE ? SURFACE WATER CARCINOGENIC RISKS AND NONCARCINOGENIC HAZARD INDEX (H.I.)

Receptor/Pathway

Adult Recreational User

Ingestion of Fish

Cluld

Ingestion of Fish

Total

Cancer Risk

1.92E-06

3.74E-07

2.29E-06

Average Exposure

Subchronic Chronic H.I . H.I .

3.30E-01 3.58E-01

3.21E-02 3.48E-02

3.93E-01

Reasonable Maximum Exposure

Cancer Subchronic Risk H.I .

2.70E-05

4.33E-06 3.56E-01

3.13E-05

Chronic H.I .

5.98E-01

3.84E-01

9.82E-01

SOURCE: WOODWARD CLYDE CONSULTANTS, DRAFT SURFACE WATER RI REPORT

Golder Associates
TABLES SUMMARY OF UNCERTAINTY FACTORS IN THE SURFACE WATER BASELINE RISK ASSESSMENT

Uncertainty Factor

Use of cancer potency factors.

Critical toxicity values derived primarily

from animal studies.

Critical toxicity values derived primarily

from high doses, most exposures are at

low doses.

Critical toxicity values.

Not all chemicals at the site have critical

toxicity values. Metals analysis for total metals only.

Effec t of absorption.

Exposure assumptions.

Exposures assumed constant.

Exposure point concentrations.

Exposure point concentrations.

Exposure scenarios.

Method detection limits.

Sampling.

Risks/doses within an exposure route

assumed to be additive.

Risk characterization.

Effect of Uncertainty

May overestimate risks.

May over- or underestimate

risks.

May over- or underestimate

risks.

May over- or underestimate

risks.

May underestimate risks.

May overestimate risks.

May over- or underestimate

risks.

May overestimate risks.

May over- or underestimate

risks. May overestimate risks.

May overestimate risks.

May overestimate risks.

May underestimate risks.

May overestimate risks.

May over- or underestimate

risks. May overestimate risks.

Comment

Potencies are upper 95th percent confidence limits

derived from the linearized model. Considered

unlikely to underestimate true risk.

Extrapolation from animal to humans may induce

error due to differences in absorption,

pharmacokinetics, target organs, enzymes, and

population variability. Assumes linear at low doses. Tends to have

conservative exposure assumptions.

Not all values represent the same degree of certainty. All are subject to change as new evidence becomes

available.

These chemical are not addressed quantitatively.

Did not distinguish between valence or speciation. Assumed the metal was present in its most toxic

form, especially arsenic and chromium.

The assumption that absorption is equivalent across

species is implici t in the derivation of the critical

toxicity values. Absorption may actually vary with

species and age.

Assumptions regarding fish intake, population

characteristics, and exposure patterns may not

characterize exposures.

Does not account for environmental fate, transport, or

transfer which may alter concentration.

Use of 95 % UCL in calculating RME may not

accurately represent exposure levels.

Used the arithmetic mean concentration to evaluate

average exposure. May not accurately represent

exposure levels.

Use of RME as upper-bound estimate may not

accurately represent exposures.

For some chemicals, the mernod detection limit is

above a concentration which might be of concern.

Samplin g biased toward areas of known or suspected

elevated metals concentrations.

Does not account for synergism or antagonism.

Combining conservative assumptions at each step of

risk assessment may lead to highly conservative risk

estimates.

SOURCE: WOODWARD CLYDE CONSULTANTS, DRAFT SURFACE WATER RI REPORT

Golder Associates
GoldeMssociates
r

3 100000-

V

CD

~ 10000

c

o

^_l

<o 1000

c

0

2 100

0

O

o 10

N

1

1

1

/T\. T

o --Vjl -!^x

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... ._..._ __. _ . _ — _ \,A \AT

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SURFAC E WATE R HUMAN HEALTH iBfC RISK ASSESSMENT V^As

-..._. ..... _....

5*0* J»*^NL -

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X

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ro co 25

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10.00 Dissolved

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—A — CQ-6 Flow

8.00 _.._.—-_—

7.00

6.00 ^

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4.00 o

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nnn

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DRAWN A M CHECKED REVIEWED °

A T E

 JUN E 1996 SCM£ N/ A R LE NO. 2819A214

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600

540

480

420

360

o 300

Q

240

180

120

60

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C G6 Zinc Contributions at AR3 Minimum 2.5% (14.5 ug/L) Maximum 98.3% (265.2 ug/L) Average 26.8% (26.0

1 20 ug/L Aquatic Life Reference

Apr-91 Jul-91 Apr-92 May-92 May-92 May-92 May-92 Jun-92 Jun-92 Jun-92 Aug-92

A R2 Contribution 1 000 ug/L CG6 Zin c

CUEWT/PROJECT ASARCO SURFAC E WATE R HUMAN HEALTH RISK ASSESSMEN T

Golder Denver, Colorado

TTTI.E PREDICTE D ZIN C CONCENTRATION S IN TH E ARKANSA S RIVE R BELOW CALIFORNIA GULCH

DRAWN CHECKE D REVIEWED A T E

 JUNE 1996

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J O B N

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D WC NO - /REV

-

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iERPREf AlIQTlC) ! ASSESS OUTPUT

Golder Associates
Appendix A

Junel996____________________A^_____________________943-2819

APPENDIX A- INTERPRETATION OF ASSESS OUTPUT

ASSESS provides the cancer risk and hazard index calculations for all exposure pathways

evaluated at a site. All information needed to verify calculations is provided. Data are

organized and reported in categories listed below:

*• Chemical List;

>• Receptor/Pathway Summary;

*• Pathway Summary;

*• Intake Factors; and,

>• Media Concentrations.

Numbers in ASSESS are written in scientific notation. The number following the E is a

power of 10; so 1.61E-02 is 0.0161.

1 .0 CHEMICAL LIST

Table A-l lists the EPA toxicity values for each chemical. When available, values are listed

for both oral and inhalation exposure routes for either subchronic or chronic exposure

durations (reference doses or RfDs) or for carcinogenic risk (slope factors or SF). These

values are obtained using the hierarchy recommended by EPA's Risk Assessment Guidance

for Superfund sites (EPA, 1989, 1991). The first and second sources in this hierarchy are

( 1) IRIS (Integrated Risk Information System), an on-line computer database of chemical risk

information (EPA, 1992a), and (2) HEAST (Health Effect s Assessment Summary Tables)

(EPA, 1992b), EPA tables which are periodically up-dated. Toxicity values (RfDs and SFs)

do not yet exist for many chemicals. For risk assessment purposes, when this is true, a

Golder Associates
June 1996__________________A-2___________________943-2819

chemical may be discussed qualitatively in the text of the report but will not be reported

quantitatively in ASSESS.

RfDs may be derived for either subchronic or chronic exposures and are used to calculate

subchronic or chronic hazard quotients, respectively. A subchronic RfD may not exist for a

particular chemical even though a chronic RfD exists.

2.0 RECEPTOR/PATHWAY SUMMARY

Table A-2 lists each receptor and the potential health risks associated with chemical exposure

from all pathways quantitated. The potential adverse health risks are divided into two

exposure scenarios: average exposure and reasonable maximum exposure (RME). For each

exposure scenario, potential health impacts are segregated into two categories: cancer risk

and a hazard index for both subchronic and chronic scenario. The values shown on this sheet

show the total carcinogenic risks and noncarcinogenic hazards associated with average and

RME scenario for each receptor listed.

RfDs are used with a level of exposure during a specific time period and expressed as a ratio

or hazard quotient. According to the EPA (EPA 1989, 1991), generally, the greater the

value of the hazard quotient (or hazard index), the greater the level of concern for health

impacts. Another area of EPA guidance states that because H.I. is not a probability function,

an increased value does not indicate a degree of risk. The hazard index is the sum of a

number of hazard quotients for a particular pathway. A hazard index of one means the

estimated chemical intake equals the reference dose. When this occurs, a more detailed

evaluation of the site is indicated. When the H.I. is less than one, further evaluation is

generally not warranted, and the exposure is expected to be safe.

A chemical' s slope factor is multiplied by the lifetime daily average intake of that chemical in

a certain medium to estimate the incremental probability (or risk) of an individual developing

Golder Associates
June 1996__________________A-3___________________943-2819

cancer during a lifetime. When a receptor potentially is exposed to a variety of chemicals (in

a given medium) possessing slope factors, all of the products are summed to yield the total

cancer risk for those chemicals for that specific exposure pathway. This risk number is

acceptable if it is less than IE-4 or 10"4 or 1 in 10,000.

Receptor Detail Report

This report is included in the Receptor/Pathway Summary Table (Table A-2) because it

details the carcinogenic risk and the noncarcinogenic hazard for each of the receptor' s

exposure pathway(s) for both the average and RME exposure scenarios. Total carcinogenic

risks and noncarcinogenic hazards for each receptor are also given. Each receptor may have

a number of exposure pathways. An exposure pathway is a route that a chemical may take to

reach a population or receptor. Each pathway is categorized as one of the following:

* Inhalation;

>

 Dermal contact with solids;

* Dermal contact with water;

>• Ingestionof solids; and,

* Ingestion of water.

3 .0 PATHWAY SUMMARY

Table A-2 also provides the same basic information as the Receptor Detail Report described

above. The difference between the two is that the Receptor Detail Report includes all

receptors while the Pathway Summary Report is receptor-specific, providing information on

only one receptor per page.

Golder Associates
June 1996_______________A-4___________________943-2819

Pathway Detail Report

Tables A-3a through A-3d comprise the majority of the ASSESS report. For both average

and RME exposure scenarios, carcinogenic risk and noncarcinogenic hazards are listed for

each receptor exposure route and chemical. Total carcinogenic risks and noncarcinogenic

hazards are also provided. This report is especially helpful in determining which chemical(s)

is (are) driving the overall risks or hazards for a particular exposure route. Other values

provided in this report include the concentration of each chemical in the medium, the intake

factor for that exposure route, and the daily intake of the chemical being evaluated. This

daily intake of an individual chemical is either multiplied by its slope factor or divided by its

RfD for a given exposure route (oral or inhalation). Until other information is available from

EPA, oral RfDs and SFs are used for assessing the potential health impacts of dermal

exposure.

4 .0 INTAKE FACTORS

Table A-4a and A-4b represent, in equation format, the method of calculating the intake

factors that appear in the pathway detail report explained above. Each of the parameters that

goes into an intake factor equation is defined for both the average and RME scenarios. These

parameters are more full y described in the Exposure Assessment section of this report.

5.0 MEDIA CONCENTRATIONS

Table A-5 describe the chemical concentrations for the average and RME scenarios for a

given medium. In some cases, a higher concentration may be used to evaluate short-term

risks. For example, particulate concentrations in air may be higher during a short

construction project than the long-term (25 year) average might be. In most cases, the same

concentrations will be used for subchronic and chronic scenario. These figures are described

in the Data Summary and Selection of Chemicals of Concern section of this report.

Golder Associates
June 1996__________________A-5___________________943-2819

6.0 REFERENCES

Environmental Protection Agency (EPA). 1989. Risk Assessment Guidance for Superfund. Volume I: Human Health Evaluation Manual. Interim final. Office of Emergency and Remedial Response. Washington, D.C. EPA/540/1-89/002.

Environmental Protection Agency (EPA). 1991. Risk Assessment Guidance for Superfund: Volume I - Human Health Evaluation Manual (Part B, Development of Risk-based Preliminary Remediation Goals). Interim. 9285.7-01B.

Environmental Protection Agency (EPA). 1992a. Integrated Risk Information System

(IRIS). On-line database.

Environmental Protection Agency (EPA). 1992b. Health Effect s Assessment Summary Tables (HEAST). Annual FY-1992. OHEA-ECAO-CIN-821. March.

Goider Associates
Table A-l Chemical List

——— — Inhalatio n ————————————— — ——— — Non-Inhalatio n ————————— — Slop e Subchronic Chronic Slop e Subchronic Chronic Facto r RF O RF D Facto r RF D RF D

Chemical (mg/kg/day ) -1 mg/kg/da y mg/kg/da y (nig/kg/day)- ! mg/kg/da y mg/kg/da y

Arsenic

 1.50E+01 1.75E+00 3.00E-04 3.00E-04 Cadmium (food ) 1.00E-03

Chromium II I 2.00E-05 2.00E-06 1.00E+00 1.00E+00

Chromium VI 4.10E+01 5.70E-06 5.70E-07 2.00E-02 5.00E-03

c

°PPe r 3.70E-02 3.70E-02 Mercury 8.60E-05 8.60E-05 3.00E-04 3.00E-04

zinc

 2.00E-01 3.00E-01

Februar y 2, 1993

18:10
Receptor / Pathway

ADULT RECREATIONA L USER

-- Ingestio n of Fish

CHIL D RECREATIONA L USE R

-- Ingestio n of Fis h

Table A-2 Receptor/Pathway Summary

Average Exposure

Cancer Subchronic Chronic Risk H.I . H.I .

Reasonable Maximun Exposure

Cancer Subchronic Chronic Risk H.I . H.I .

1.92E-06 3.30E-01 3.58E-01 2.70E-05 5.55E-01 5.98E-01

1.92E-06 3.30E-01 3.58E-01 2.70E-05 5.55E-01 5.98E-01

3.74E-07 3.21E-02 3.48E-02 4.33E-06 3.56E-01 3.84E-01

3.74E-07 3.21E-02 3.48E-02 4.33E-06 3.56E-01 3.84E-01

Februar y 2, 1993

18:10
Table A-3a ADULT RECREATIONAL USER

Ingestion of Fish Average Exposure

| Carcinogenic Risk

i

Chemical

Arseni c

i

| Hazard Index -- Subchronic

i

Chemical

Arseni c Chromium V I

Copper Mercury Zin c

i

| Hazard Index -- Chroni c

i

Chemical

Arsenic Chromium V I

Copper Mercury Zin c

I

1I

Chemical

Concentratio n

(nig/kg )

3.00E-02

I

iI

Chemical

Concentratio n

(mg/kg )

3.00E-02

2.80E-01

3.80E-01

7.00E-02

5.62E+00

~1

II

Chemical

Concentratio n

(mg/kg )

3.00E-02

2.80E-01

3.80E-01

7.00E-02

5.62E+00

Ingestio n Intak e Facto r

(kg/kg/day )

3.66E-05

Ingestio n Intak e Facto r

(kg/kg/day )

8.55E-04

8.55E-04

8.55E-04

8.55E-04

8.55E-04

Ingestio n Intak e Facto r

(kg/kg/day )

8.55E-04

8.55E-04

8.55E-04

8.55E-04

8.55E-04

Dail y Intak e

(mg/kg/day )

1.10E-06

Dail y Intak e

(mg/kg/day )

2.56E-05

2.39E-04

3.25E-04

5.98E-05

4.80E-03

O ai l y Intak e

(mg/kg/day )

2.56E-05

2.39E-04

3.25E-04

5.98E-05

4.80E-03

Slop e Facto r

. (mg/kg/day ) -1

1.75E+00

Subchronic R F D

(mg/kg/day )

3.00E-04

2.00E-02

3.70E-02

3.00E-04

2.00E-01

Chroni c R F D

(mg/kg/day )

3.00E-04

5.00E-03

3.70E-02

3.00E-04

3.00E-01

Carcinogenic Risk

1.92E-06

Hazard

Quotien t

8.55E-02

1.20E-02

8.78E-03

1.99E-01

2.40E-02

Hazard

Quot i ent

8.55E-02

4.79E-02

8.78E-03

1.99E-01

1.60E-02

Tota l

Risk

1.92E-06

Hazard

Index

3.30E-01

Hazard

Index

3.58E-01
Table A-3b ADULT RECREATIONAL USER

Ingestion of Fish Reasonable Maximum Exposure

1

| Carcinogenic Risk

i

Chemical

Arsenic

i

| Hazard Index -- Subchronic

i

Chemical

Arsenic

Chromium V I

Copper

Mercury Zin c

| Hazard Index -- Chronic

i

Chemical

Arsenic Chromium VI

Copper Mercury Zin c

1

Chemical

Concentration

(mg/kg )

4.00E-02

I

1I

Chemical

Concentration

(mg/kg )

4.00E-02

3.30E-01

4.20E-01

9.00E-02

6.42E+00

I

II

Chemical

Concentratio n

(mg/kg )

4.00E-02

3.30E-01

4.20E-01

9.00E-02

6.42E+00

Ingestio n

Intake Factor

(kg/kg/day )

3.86E-04

Ingestio n

Intake Factor

(kg/kg/day )

1.12E-03

1.12E-03

1.12E-03

1.12E-03

1.12E-03

Ingestio n Intak e Facto r

(kg/kg/day )

1.12E-03

1.12E-03

1.12E-03

1.12E-03

1.12E-03

Dail y Intak e

(mg/kg/day )

1.54E-05

4 Dail y Intake

(mg/kg/day )

4.50E-05

3.71E-04

4.72E-04

1.01E-04

7.22E-03

Dail y Intak e

(mg/kg/day )

4.50E-05

3.71E-04

4.72E-04

1.01E-04

7.22E-03

Slop e Factor

(nig/kg/day)- !

1.75E+00

Subchronic R F D

(mg/kg/day )

3.00E-04

2.00E-02

3.70E-02

3.00E-04

2.00E-01

Chroni c R F D

(mg/kg/day )

3.00E-04

5.00E-03

3.70E-02

3.00E-04

3.00E-01

Carcinogenic Risk

2.70E-05

Hazard

Quotien t

1.50E-01

1.86E-02

1.28E-02

3.37E-01

3.61E-02

Hazard

Quotien t

1.50E-01

7.42E-02

1.28E-02

3.37E-01

2.41E-02

Tota l

Risk

2.70E-05

Hazard

Index

5.55E-01

Hazard

Index

5.98E-01
Table A-3c CHILD RECREATIONAL USER

Ingestion of Fish Average Exposure

1

| Carcinogenic Risk

i

Chemical

Arsenic

i

| Hazard Index -- Subchronic

i

Chemical

Arsenic

Chromium VI

Copper Mercury Zin c

i

| Hazard Index -- Chronic

i

Chemical

Arsenic

Chromium V I

Copper Mercury Zin c

1

Chemical

Concentratio n

Cmg/kg )

3.00E-02

\

\1

Chemical

Concentratio n

(mg/kg )

3.00E-02

2.80E-01

3.80E-01

7.00E-02

5.62E+00

1

1I

Chemical

Concentratio n

(ing/kg )

3.0uE-02

2.80E-01

3.80E-01

7.00E-02

5.62E+00

Inges t ion Intak e Facto r

(kg/kg/day )

7.13E-06

Ingestio n Intake Facto r

(kg/kg/day )

8.32E-05

8.32E-05

8.32E-05

8.32E-05

8.32E-05

Ingestio n Intak e Facto r

(kg/kg/day )

8.32E-05

8.32E-05

8.32E-05

8.32E-05

8.32E-05

O ai ly Intake

(mg/kg/day )

2. HE-07

Dail y Intake

(ing/kg/day )

2.50E-06

2.33E-05

3.16E-05

5.83E-06

4.68E-04

Dail y Intak e

(mg/kg/day )

2.50E-06

2.33E-OS

3.16E-05

5.83E-06

4.68E-04

Slop e Facto r

. (mg/kg/day ) -1

1.75E+00

Subchronic R F D

(mg/kg/day )

3.00E-04

2.00E-02

3.70E-02

3.00E-04

2.00E-01

~

Chronic R F O

(mg/kg/day )

3.00E-04

5.00E-03

3.70E-02

3.00E-04

3.00E-01

Carcinogenic Risk

3.74E-07

Hazard

Quotien t

8.32E-03

1.17E-03

8.55E-04

1.94E-02

2.34E-03

Hazard

Quotient

8.32E-03

4.66E-03

8.55E-04

1.94E-02

1.56E-03

Tota l

Risk

3.74E-07

Hazard

Index

3.21E-02

Hazard

Index

3.48E-02
Table A-3d CHILD RECREATIONAL USER

Ingestion of Fish Reasonable Maximum Exposure

1

| Carcinogenic Risk

i

Chemical

Arsenic

i

| Hazard Index -- Subchronic

i

Chemical

Arsenic

Chromium V I

Copper Mercury Zin c

i

| Hazard Index -• Chronic

i

Chemical

Arsenic

Chromium VI

Copper Mercury Zin c

1

1I

Chemical

Concentratio n

(mg/kg )

4.00E-02

1

1

Chemical

Concentratio n

(mg/kg )

4.00E-02

3.30E-01

4.20E-01

9.00E-02

6.42E+00

1

1I

Chemical

Concentratio n

(mg/kg )

4.00E-02

3.30E-01

4.20E-01

9.00E-02

6.42E+00

Ingestio n Intak e Facto r

(kg/kg/day )

6.18E-05

Ingestio n Intak e Facto r C kg/kg/day )

7.21E-04

7.21E-04

7.21E-04

7.21E-04

7.21E-04

Ingestio n Intak e Facto r

(kg/kg/day )

7.21E-04

7.21E-04

7.21E-04

7.21E-04

7.21E-04

Dail y Intak e

(mg/kg/day )

2.47E-06

Oafl y Intake

(mg/kg/day )

2.88E-05

2.38E-04

3.03E-04

6.49E-05

4.63E-03

Dail y Intak e

(mg/kg/day )

2.88E-05

2.38E-04

3.03E-04

6.49E-05

4.63E-03

Slop e Facto r

.(mg/kg/ day) -1

1.75E+00

Subchronic R F D

(mg/kg/day )

3.00E-04

2.00E-02

3.70E-02

3.00E-04

2.00E-01

Chronic R F D

(mg/kg/day )

3.00E-04

5.00E-03

3.70E-02

3.00E-04

3.00E-01

Carcinogenic Tota l

Risk Risk

4.33E-06

4.33E-06

Hazard Hazard

Quotien t Index

9.62E-02

1.19E-02

8.19E-03

2.16E-01

2.32E-02

3.56E-01

Hazard Hazard

Quotien t Index

9.62E-02

4.76E-02

8.19E-03

2.16E-01

1.54E-02

3.84E-01
Table A-4a

Intake Factor: SURFACE WATER

Description : Adul t Recreational User - Fish Inges t io n Abbreviation : AUF G

Pathway Type: Inges t ion of Soi l

Intake Factor

( IR x EF x ED x HE x FI x CF x SS )

( BU x AT )

February 2, 199

18:1

Parameters:

Carcinogenic •

Abbreviation

I R

EF

ED

ME

F I

CF

SS

BW

AT

Descriptio n

Inges t ion Rate(mg/day)

Exposure Freq.(dys/yr )

Exposure Duration(yrs) Matri x Effec t

Fractio n Contaminated

Conversion Facto r (kg/mg ) Site-specifi c Factor Body Weigh t (kg ) Averagin g Tim e (dys)

A ve

150000

52

3

1

1

.000001

1

25

25550

RME

150000

156

24

1

1

.000001

1

57

25550

Non - Carcinogenic A ve

 150000

52

3

1

1

.000001

1

25

1095

R ME

150000

156

24

1

1

.000001

1

57

8760

Intak e Facto r Calculations :

Carcinogenic: Average Exposure

( 1.50E+05 x 5.20E+01 x 3.00E+00 x 1 x 1 x 1.00E-06 x 1 )

3.66E-05 =

( 2.50E+01 x 2.56E+04 )

Carcinogenic: Reasonable Maximum Exposure

( 1.50E+05 x 1.56E+02 x 2.40E+01 x 1 x 1 x 1.00E-06 x 1 )

3.86E-04 =

( 5.70E+01 x 2.56E+04 )

Non-Carcinogenic: Average Exposure

( 1.50E+05 x 5.20E+01 x 3.00E+00 x 1 x 1 x 1.00E-06 x 1 )

8.55E-04 =

( 2.50E+01 x 1.10E+03 )

Non-Carcinogenic: Reasonable Maximum Exposure

< 1.50E+05 x 1.56E+02 x 2.40E+01 x 1 x 1 x 1.00E-06 x 1 )

1.12E-03 =

( 5.70E+01 x 8.76E+03 )
Table A-4b

Intake Factor: SURFAC E WATE R

Description : Chil d Recreational User - Fis h Inges t io n Abbreviation : CUF G

Pathway Type: Inges t io n of Soi l

Intak e Facto r

( IR x EF x ED x ME x FI x CF x SS )

( BW x AT )

Februar y 2, 199

18:1

Parameters:

Carcinogenic Abbreviatio n

!R

EF

ED

ME

F I

CF

SS

8U

A T

Descriptio n

Inges t io n Rate(mg/day )

Exposure Freq.(dys/yr )

Exposure Duration(yrs ) Matri x Effec t

Fractio n Contaminated

Conversion Facto r (kg/mg ) Site-specifi c Facto r Body Weigh t (kg ) Averagin g Tim e <dys)

A ve

81000

6

6

1

1

.000001

1

16

25550

R ME

81000

52

6

1

1

.000001

1

16

25550

Non-Carcinogeni c A ve

'8100 0

6

6

1

1

.000001

1

16

2190

R ME

81000

52

6

1

1

.000001

1

16

2190

Intak e Facto r Calculations :

Carcinogenic: Average Exposure

( 8.10E+04 x 6.00E+00 x 6.00E+00 x 1 x 1 x 1.00E-06 x 1 )

7.13E-06 =

( 1.60E+01 x 2.56E+04 )

Carcinogenic: Reasonable Maximum Exposure

( 8.10E+04 x 5.20E+01 x 6.00E+00 x 1 x 1 x 1.00E-06 x 1 }

6.18E-05 =

( 1.60E+01 x 2.56E+04 )

Non-Carcinogenic: Average Exposure

( 8.10E+04 x 6.00E+00 x 6.00E+00 x 1 x 1 x 1.00E-06 x 1 )

8.32E-05 =

( 1.60E+01 x 2.19E+03 )

Non-Carcinogenic: Reasonable Maximum Exposure

( 8.TOE+04 x 5.20E+01 x 6.00E+00 x 1 x 1 x l.OOE-06 x 1 )

7.21E-04 =

( 1.60E+01 x 2.19E+03 )
Table A-5

Media Chemical Concentrations: SURFACE WATER Februar y 2, 199

18:1

Median : Fish

Abbreviation : FIS H

Medium Type: Soi I

Subchronic Chronic/Carcinogeni c

Chemical Average(mg/kg ) R.H.E .

(mg/kg )

Arsenic

Cadmium (food ) Chromium II I

Chromium V I

Copper

Mercury Zin c

3.00E-02 4.00E-02

2.80E-01 3.30E-01

3.80E-01 4.20E-01

7.00E-02 9.00E-02

5.62E+00 6.42E+00

Average

(mg/kg )

R.M.E .

(mg/kg )

3.00E-02 4.00E-02

2.80E-01 3.30E-01

3.80E-01 4.20E-01

7.00E-02 9.00E-02

5.62E+00 6.42E+00