# Appendix 9

Technical Support Document: Human Health Multipathway Res idual Risk Screening Assessment for the P rimary Aluminum Reduction

Source Category

## Technical Support Document: Huma n Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

DRAFT
July 10, 2014

Prepared For:

U.S. Environmental Protection Agency Office of Air Quality Planning and Standards Research Triangle Park, NC 27711

Under Contract No. EP-12-010, Work Assignment 2-20

Prepared By:

ICF International 2635 Meridian Pkwy. Suite 200 Durham, NC 27713[This page intentionally left blank.]Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft iii July 2014 

## CONTENTS

Tables ........................................................................................................................ .................. iii

Figures ....................................................................................................................... .................. iii

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

2. Tier 1 Emission Screening Assessment ............................................................................... 2

2.1 Tier 1 Emission Screening Results for this Source Category ...................................... 3

3. Tier 2 Emission Screening Assessment ............................................................................... 3

3.1 Adjustment Factors Applied to Tier 1 Screening Values ............................................. 4

3.2 Calculating Refined Tier 2 Fisher Screening Values ................................................... 5

3.3 Finalizing Tier 2 Farmer Screening Values ................................................................. 6

3.4 Tier 2 Screening Results for this Source Category ..................................................... 6

4. Tier 3 Emission Screening Assessment ............................................................................... 9

4.1 Lake Assessment ........................................................................................................ 9

4.2 Tier 3 Lake Assessments Results for this Source Category ..................................... 11

4.3 Plume-rise Assessment ............................................................................................. 14

4.4 Tier 3 Plume-rise Assessment Results for this Source Category .............................. 14

5. Comparison to Tier 1 Screening Results for this Source Category .................................... 16

6. References .................................................................................................................... ..... 18



## TABLES Table 2-1. Tier 1 Emission Screening Results for this Source Category ...................................... 3 Table 3-1. Tier 2 Screening Results for this Source Category ...................................................... 8 Table 4-1. Results of Tier 3 Lake Assessments in this Source Category ................................... 11 Table 4-2. Results of Tier 3 Plume-rise Assessments in this Source Category .......................... 15

Table 4-3. Tier 3 SVs Before and After Additional Lake and Plume-rise Assessments in this Source Category .................................................................. 16 Table 5-1. Comparison of Tier 1 and Tier 3 Screening Results for this Source Category ............................................................................................................... 18



## FIGURES Figure 4-1. Example of Lake Removed from Screening—Likely Covered in Algae or Thick Plant Matter ............................................................................................ 10 Figure 4-2. Example of Lake Removed from Screening—Likely an Industrial Lake ................... 10 Figure 4-3. Lakes Assessed for Cadmium Emissions at NEIWA19906 ...................................... 13Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft iv July 2014 

### Figure 4-4. Lakes Assessed for PAH and Dioxin Emissions at NEI46970 ................................. 13Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 1 July 2014 

## 1. Introduction

This report provides a discussion on a screening-level assessment of human health risks, via the ingestion pathway, from exposure to persistent and bioaccumulative hazardous air pollutants (PB-HAPs) emitted to the air from primary aluminum production facilities. While this report contains a discussion on some of the screening methods, a more detailed discussion on the development, methods, and implementation of the screening assessment can be found in Appendix 5 of the Risk Report. 1 

### Where appropriate, this discu ssion provides references to particular sections of Appendix 5 to the Risk Report, where further details on the subject matter can be found.

Cadmium, dioxins, mercury, and polycyclic arom atic hydrocarbons (PAHs) were the evaluated PB-HAP groups, 2 

### selected from a larger list of PB-HAPs based in part on ranking their toxicityweighted air emissions across all source categories. The evaluated exposure scenarios were a fisher scenario (i.e., consumption of fish from a lake) and a farmer scenario (i.e., consumption of farm food chain [FFC] media such as animal products, fruits and vegetables, and incidental ingestion of soil). EPA evaluates the two scenarios together (i.e., the sum of fisher and farmer exposures and risks) in the first tier of the assessment, and EPA evaluates them separately in the second and third tiers. EPA designed the screening scenarios to be health-protective in estimating exposures and risks. Specifically, they are intended to avoid underestimating ingestion exposure and risk due to the air emissions of these PB-HAPs from facilities nationwide evaluated in the Risk and Technology Review (RTR) program.

EPA uses the TRIM.FaTE 3 

### model to evaluate the environmental transport, transfer, and fate of PB-HAP air emissions. The MIRC 4 

### program then calculates FFC chemical uptake along with human exposure, human health cancer risks, an d human health non-cancer hazard quotients (HQs) resulting from ingestion of fish and FFC media. For screening assessments of multipathway risk across the RTR program, EPA used these models with fate and transport parameter values, idealized spatial layouts, and generalized meteorology that overall create ingestion exposure situations that are unlikely to be exceeded at any actual facility evaluated in the RTR program. ICF (hereafter “we”) conducted these model runs to identify threshold emission rates (hereafter “thresholds”) that correspond to levels of concern for cancer risks and HQs. The levels of concern are incremental, lifetim e, human cancer risks of 1-in-one million (for PAHs and dioxins) and chronic, non-cancer HQs of 1 (for cadmium and mercury).

For the iterative (“tiered”) screening-level ingestion assessment described in this report, we assessed the potential for ingestion risks above levels of concern in the primary aluminum production source category by comparing PB-HAP emissions from facilities within the source category to the thresholds. We use the term “screening values” (SVs) to refer to the ratio of a facility’s emissions of a PB-HAP to that PB-HAP’s threshold. When rounded to one significant

1 Appendix 5 to the Risk Report is the Technical Support Document for t he TRIM-Based Multipathway Tiered Screening Methodology for RTR

. 2 The phrase “PB-HAP group” is used to distinguish the in dividual PB-HAP chemicals and congeners from the overall family (grouping) of those chemicals. For example, EPA’ s ingestion risk methods in its Risk and Technology Review (RTR) program evaluate emissions of 17 individual cong eners of chlorinated dibenzo-p-dioxins and chlorinated dibenzofurans in the “dioxin” PB-HAP group.

3 TRIM.FaTE is the Fate, Transport, and Ecological Expos ure module of the Total Risk Integrated Methodology modeling system. Additional TRIM.FaTE information can be found at: http://www2.epa.gov/fera /total-risk-integratedmethodology-trim-trimfate

. 4 MIRC is the Multimedia Ingestion Risk Calculator.Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 2 July 2014 

### figure, an SV of 1 or lower indicates that the emissions did not exceed the threshold and are unlikely to pose health risks above levels of concern (i.e., the emissions “screened out”). An SV of 2 or higher indicates that the emissions exceeded the threshold and potentially pose health risks above levels of concern.

The primary aluminum production source category contains 13 facilities. As described in this report, each facility emitted PAHs and dioxins at levels exceeding Tier 1 thresholds, and 10 of the facilities also emitted cadmium and/or mercur y at levels exceeding Tier 1 thresholds. In the Tier 2 screening, emissions of cadmium ex ceeded the fisher threshold at one facility (NEIWA19906), and emissions of mercury exce eded the fisher threshold at one facility (NEI41217). The cadmium emissions at NEIWA19906 and mercury emissions at NEI41217 screened out in Tier 3, which included additional assessments of its emissions and corresponding meteorology and/or lake data. The highest fisher and farmer SVs for PAH emissions, and highest farmer SV for dioxin emissions, correspond to one facility (NEI46970); these emissions did not screen out in Tier 3.

In Sections 2, 3, and 4, we briefly describe the Tiers 1, 2, and 3 screening methods and discuss the results of those screening assessments. We provide in Section 5 a summary comparison of the Tier 1 screening results with the screening results after the Tiers 2 and 3 assessments. 

## 2. Tier 1 Emission Screening Assessment

The thresholds developed for Tier 1 are intended to apply to any U.S. facility; that is, EPA designed them to be applicable to every facility regardless of the facility’s characteristics and surrounding environment and the population exposed in its vicinity. The approach to develop the thresholds 5 

### assumes ingestion exposure situations that are unlikely to be exceeded at any actual facility evaluated in the RTR program. Thi s health-protectiveness is achieved by several methods, including (but not limited to): (1) an idealized spatial layout where the evaluated lake and farming area are within 2 to 3 km of the emission source and, thus, receive high levels of direct deposition; (2) a watershed design where the lake receives substantial indirect chemical deposition through large magnitudes of runoff and erosion; (3) a meteorology scenario that enhances air concentrations and chemical deposition; and, (4) relatively high ingestion rates representing subsistence-level consumption of fish and FFC media.

Each evaluated PB-HAP group has a single Tier 1 threshold, as shown in Table 2-1 (column e). For Tier 1, EPA normalizes the emissions of a ll dioxin congeners to 2,3,7,8-tetrachlorodibenzop-dioxin-equivalent emissions, and EPA normalizes the emissions of all PAH congeners to benzo(a)pyrene-equivalent emissions. 6 

### These normalization factors (i.e., exposure equivalency factors [EEFs]) are based on oral toxicity factors and factors related to the congeners’ environmental fate and transport characterist ics as analyzed in the TRIM.FaTE model. 7 

### For mercury, EPA established the threshold for emissions of divalent mercury, although the threshold is based on hazards associated with in gestion of methyl mercury from contaminated fish (with relatively minimal contribution from ingestion of divalent mercury from FFC media). 8

5 See Appendix 5 of the Risk Report (Sections 1 and 2) for additional information.

6 We sometimes use 2,3,7,8-TCDD and BaP this report as s horthand terms for 2,3,7,8-tetrachlorodibenzo-p-dioxin and benzo(a)pyrene, respectively.

7 See Appendix 5 to the Risk Report (Section 2.2.7) fo r additional information on Tier 1 screening methods.

8 TRIM models mercury transformation in the environmen t, and exposure in the screening scenario associated with ingestion of fish contaminated with methyl mercury (relat ed to emissions of divalent mercury and transformation toHuman Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 3 July 2014 

### 2.1 Tier 1 Emission Screening Re sults for this Source Category

As shown in Table 2-1, emissions of mercury exceeded the threshold at nine facilities, and the highest SV was 10 (at NEIKY0912109100004, a Century Aluminum of Kentucky facility in Hawesville, KY). Emissions of cadmium exceeded the threshold at six facilities, and the highest SV was 30 (at NEIWA19906, an Alcoa facility in Ferndale, WA). NEI46970 (a Reynolds Metals facility in Massena, NY) had the highest SV for PAHs (SV = 2,000) and dioxins (SV = 200), though all facilities exceeded the thresholds for PAHs and dioxins.

When PAH and dioxin SVs were summed together per facility (i.e., calculating the total PAH+dioxin screening-level potential cancer risk), the highest total “cancer SV” was 2,000 and all total “cancer SVs” were 20 or higher.

Table 2-1. Tier 1 Emission Screening Results for this Source Category

PB-HAP Group (a) Num. Facil. Exceeding Threshold (b) Highest SV [(d)/(e)] (c) Facil. with Highest SV (d) Emiss. at Facil. with

Highest SV (TPY) a (e) Emiss. Screening

Thresh.

(TPY) Mercury b (non-cancer) 9 10 NEIKY0912109100004 (Century Aluminum of Kentucky LLC; Hawesville, KY) 3.21E-03 3.16E-04

Cadmium (non-cancer) 6 30 NEIWA19906 (Alcoa Primary Metals Intalco Works; Ferndale, WA) 3.46E-01 1.18E-02

PAHs as BaP (cancer) 13 2,000 NEI46970 (Reynolds Metals, St. Lawrence Reduction Plant; Massena, NY) 4.54 2.58E-03

Dioxins as 2,3,7,8- TCDD (cancer) 13 200 NEI46970 (Reynolds Metals, St. Lawrence Reduction Plant; Massena, NY) 6.24E-07 2.81E-09

Notes: TPY = tons per year. SVs rounded to one significant figur e. Cell shadings indicate records corresponding to SVs of 2 or higher (i.e., the emissions exceeded the threshold).

a We normalized PAH and dioxin emissions in th is column to BaP and 2,3,7,8-TCDD, res pectively, for oral toxicity and Tier 1 modeled environmental fate and transport.

b The emission screening threshold for mercury applies to emissions of divalent merc ury, although EPA derived it based on hazards associated with ingestion of fish contaminat ed with methyl mercury (i.e., emissions of divalent mercury, which transforms to me thyl mercury within the environment, accumulates in fish tissue, and is consumed by the fisher). The contribution from hazards associated ingestion of divalent mercu r y from contaminated FFC or fish media is relatively minimal.


## 3. Tier 2 Emission Screening Assessment

The generic site characteristics used in Tier 1 ca n differ from those actually present at many facilities. In Tier 2, EPA takes into account so me site-specific characteristics—specifically, meteorological conditions and locations of potentially fishable lakes—to apply adjustments to the Tier 1 SVs, creating Tier 2 SVs. 9



### For a facility undergoing Tier 2 screening, EPA par titions the 50-km area around the facility into eight “wedges” or “octants” centered on the facility and compartmentalizing areas north of the facility, northeast, east, and so on. As described in Section 3.1, the lake locations and some

methyl mercury) results in much larger hazards than exposur e associated with ingestion of fish or FFC contaminated with divalent mercury. (See Section 2.2 and 2.5.3 in Appendix 5 to the Risk Report.)

9 See Appendix 5 to the Risk Report (Sections 1.2 and 3) for additional information on Tier 2 screening methods.Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

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### meteorological conditions related to a facility can vary by octant in Tier 2. Though the distance from facility to modeled farm remains fixed for each octant, EPA adjusts the location of the modeled lake based on actual lake locations. This affects chemical concentrations in some FFC media due to modeled erosion and runoff patterns that are directed mostly toward the lake. Therefore, for every relevant PB-HAP emitted by a facility, EPA calculates the fisher SV of each lake, using the distance from facility to lake and the meteorology conditions of the octant the lake is in; and, since lake location can affect the farm SV, EPA calculates a corresponding farmer SV for each lake scenario.

Based on the Tier 2 SVs and other considerations with respect to the source category being assessed, EPA might conduct a Tier 3 assessment on some facilities, leading to adjustments to the Tier 2 SVs for those facilities. The results we present in Section 3.4 are prior to this Tier 3 assessment; we discuss the Tier 3 assessment and its effects on SVs in Section 4.



### 3.1 Adjustment Factors Applied to Tier 1 Screening Values

In developing the adjustment factors used in Tier 2, we conducted hundreds of TRIM.FaTE and MIRC model runs corresponding to ranges of meteorological characteristics expected to be found at most U.S. locations, and corresponding to lake locations ranging from 2 km to 40 km away from the facility. As in Tier 1, the model runs provided emission rates corresponding to risk and hazard levels of concern. Because each modeled scenario has different environmental fate and transport characteristics, each scenario also has different EEFs to relate PAH and dioxin congeners to BaP and 2,3,7,8-TCDD, respectively. Unlike in Tier 1, EPA calculates EEFs and thresholds separately in Tier 2 for the fisher and farmer scenarios. The Tier 2 adjustment factors are the ratios of the Tier 2 EEFs and thresholds to those of Tier 1. EPA applies the Tier 2 adjustment factors to Tier 1 SVs in order to calculate Tier 2 fisher SVs and Tier 2 farmer SVs. We discuss below an additional adjustment factor based on wind direction.

In order to match an assessed facility in Tier 2 with its appropriate meteorology- and lakerelated Tier 2 adjustment factors, EPA matches the facility with the same meteorology station to which it is matched in the RTR inhalation risk assessment (i.e., typically the closest station), and EPA also identifies qualifying lakes around the facilit y. Some of a facility’s meteorology patterns vary by octant, and qualifying lakes (discussed below) can be scattered around multiple octants and at multiple distances from the facility. Therefore, for each lake in each octant around a facility, EPA matches its combination of meteorology data and lake distance to its appropriate scenario in the Tier 2 model runs and, thus, to the appropriate Tier 2 adjustment factors.

EPA bases the meteorology data used in Tier 2 on the same dataset used in RTR inhalation risk assessments, consisting of more than 800 meteorology stations nationwide. We processed hourly data from the meteorology stations to derive typical or total station-specific values of wind speed, wind direction, mixing height, and precipitation. For each station, we then matched the combination of these values with the most representative meteorological scenario used in the Tier 2 model runs. The matching method is health-protective (i.e., wind speeds and mixing heights match to their closest, smaller value in the Tier 2 model runs, and a precipitation value to its closest, larger value). We also calculated the frequency of winds blowing toward each of the octants around each station. EPA compares the frequency of winds blowing into an octant to the frequency used in Tier 1, creating a Tier 2 wind frequency adjustment factor.Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 5 July 2014 

### EPA analyzes all qualifying lakes within 50 km of t he facility. A qualifying lake (1) is at least 25 acres in surface area but no larger than 100,000 acres; 10 

### (2) is classified by USGS as a lake or reservoir but not used for disposal, treatment, or evaporator purposes; (3) does not have a name suggesting it is not intended for public use (e.g., “Gavin Fly Ash Impoundment”); and, (4) has not been removed in previous source ca tegory assessments based on these and other inspection methods. EPA assigns each lake to its respective octant around the assessed facility and to the closest lake distance value used in the Tier 2 model runs, where the matching method is health-protective (i.e., a lake’s distance matches to its closest, smaller value in the Tier 2 model runs). In cases where there are no qualifying lakes around the facility, there is no exposure or risk to the fisher.

The Tier 2 fisher and farmer SVs calculated at this point in the assessment are “initial SVs”; this is because subsequent steps in Tier 2 refine the fisher SVs (see Section 3.2) and select one of the potentially many farmer SVs (see Section 3.3).


### 3.2 Calculating Refined Tier 2 Fisher Screening Values

The subsistence fisher in Tier 1 consumes fish from one lake at the subsistence ingestion rates, regardless of the lake’s ability to support a fish population that allows for that level of consumption across many years. In Tier 2, EPA considers the lake’s capacity to accommodate the assumed fish ingestion rates. For any particular lake, the fisher in Tier 2 catches and consumes fish from that lake at an amount propor tional to the area of the lake, which serves as an approximation of the lake’s biological productivity. 11 

### In order to consume fish at the ingestion rate used in Tier 2, the fisher might need to fish multiple lakes (and be exposed to several different chemical concentration levels in fish).

The initial Tier 2 fisher SVs and the Tier 1 fisher SVs use a fixed set of fish ingestion rates covering a range of ages. The highest fish ingestion rate among the age groups is 373 g fish/d for adults, which for simplicity EPA uses to esti mate a lake’s capacity to support subsistence fishing. Smaller lakes are unlikely to support this level of fish consumption over time (i.e., the lake would be “fished out”), although the fisher could catch and consume that amount of fish collectively from multiple small lakes. In Tier 2, EPA assumes that a fisher can catch and consume no more than 1 g fish/d/acre lake without impacting the lake’s long-term sustainability. In order to reach the assumed ingestion rate, EPA assumes that the fisher catches and consumes fish from one or more lakes until he is able to fish a total of 373 acres of lake and consume a total of 373 g fish/d (i.e., the screening scenario adult fish ingestion rate) or until there are no more qualifying lakes to fish to reach 373 total acres.

EPA uses the initial Tier 2 fisher SVs calculated for all qualifying lakes around a facility, along with the acreage values of those lakes, to identify which lake(s) the fisher catches and consumes fish from and the amount of fish caug ht from each lake. Using this information, EPA refines the Tier 2 fisher SV based on a scenario assuming consumption of fish from multiple lakes. EPA conducts the steps below for each PB-HAP group emitted by a facility.

10 Discussed further in Appendix 5 (Section 3 and Attachment E) to the Risk Report.

11 See Appendix 5 to the Risk Report (Section 3 and Attachment E) for additional information on potential lake productivity.Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 6 July 2014 

### 1. Identify the lake with the highest chemical concentration in fish 12 

### for a given PB-HAP group, according to the initial Tier 2 fisher SVs. 2. If the lake with the highest concentration is at least 373 acres in area, then the fisher consumes fish from only that lake, at the subsistence-level ingestion rates (the adult rate being 373 g fish/d). That is, the refined Tier 2 fisher SV equals the initial Tier 2 fisher SV. 3. If the lake with the highest concentration is smaller than 373 acres, then the fisher catches only the amount of fish consistent with the assumption of 1 g fish/d/acre lake. That is, multiply the initial Tier 2 fisher SV for that lake by [its acreage]÷[373 acres]; put another way, multiply the SV by [the daily mass of fish co nsumed from the lake]÷[373 g fish/d]. Apply the following logic to subsequent lakes.
a. The fisher catches and consumes fish from one or more additional lakes, in order of highest to lowest concentration. If multiple lakes have the same concentration, then he fishes them in order of largest to smallest acreage. He stops fishing when he fishes lakes totaling 373 acres or when there are no more qualifying lakes to fish to reach 373 total acres. Scale each additional lake’s initial Tier 2 fisher SV by acreage (i.e., by fish consumption rate) in the same way as the first fished lake (see above). b. If the cumulative area of all qualifying lakes is smaller than 373 acres (i.e., if all lakes together cannot support a 373 g fish/d adult ingestion rate, assuming 1 g fish/d/acre lake), then the fisher does not consume the full 373 g fish/d. c. If the cumulative area of all qualifying lakes is larger than 373 acres, the fisher consumes only the amount of fish from the final lake necessary to reach 373 g fish/day. That is, scale the initial Tier 2 fisher SV for that lake by [the remaining acreage necessary to reach 373 acres, after fishing the prior lake(s)]÷[373 acres]. d. The refined Tier 2 fisher SV (reflecting the refined fisher methods) is the sum of the adjusted Tier 2 fisher SVs of all fished lakes as calculated above.



### 3.3 Finalizing Tier 2 Fa rmer Screening Values

For a given PB-HAP group emitted by a facility, EPA identifies the highest Tier 2 farmer SV from all the relevant meteorology and lake-distance scenarios. This helps to avoid underestimating exposure and risk.


### 3.4 Tier 2 Screening Results for this Source Category

In this section, we discuss the Tier 2 screening results. The results in this section use the refined Tier 2 fisher SVs (discussed in Section 3.2) and the highest Tier 2 farmer SVs (discussed in Section 3.3).

As shown in Table 3-1, emissions of mercury and cadmium screened out for the farmer, though the mercury fisher SV was 2 at NEI41217 (an Alumax of South Carolina facility in Goose Creek, SC) and the cadmium fisher SV was 2 at NEIWA19906. EPA assessed these emissions at NEI41217 and NEIWA19906 in Tier 3, as discuss ed in Section 4. Emissions of PAHs exceeded

12 In the screening assessments, for a given ingestion rate, SVs are directly and proportionally related to chemical concentrations in the exposure media. For simplicity and to more clearly relate the potential health impacts of consuming a lake’s fish to the chemical concentrations in those fish, EPA discusses fish concentrations in describing the methods of calculating the refined Tier 2 angler SVs.Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 7 July 2014 

### the fisher or farmer threshold at 11 facilities, with emissions at NEI46970 corresponding to the highest SVs (SV = 60 for fisher, SV = 100 for fa rmer). Emissions of dioxins exceeded the thresholds at 12 facilities, with the highest fisher SV of 40 corresponding to NEI32661 (Alcoa facility in Newburgh, IN) and the highest farmer SV of 20 corresponding to NEI46970. EPA assessed PAH and dioxin emissions at NEI46970 in Tier 3, as discussed in Section 4.

When PAH and dioxin SVs were summed together (i.e., calculating the total PAH+dioxin screening-level potential cancer risk), the highest total “cancer SVs” were 2 or higher for the fisher at all 13 facilities and for the farmer at 12 facilities (not shown in table).Human Health Multipathway Residual Risk Screening Assessment for thePrimary Aluminum Production Source CategoryDraft 8 July 2014Table 3-1. Tier 2 Screening Results for this Source CategoryPB-HAPGroupNum. Facil.ExceedingFisherThresholdNum. Facil.ExceedingFarmerThresholdNum. Facil. ExceedingThreshold,Either Fisher or Farmer,Both Fisher and FarmerHighestFisher SVHighestFarmer SVFacil. with HighestFisher SVFacil. with HighestFarmer SVMercurya(non-cancer)1 0102 0.0008NEI41217(Alumax of South Carolina;Goose Creek, SC)NEIWA19906(Alcoa Primary MetalsIntalco Works;Ferndale, WA)Cadmium(non-cancer)1 0102 0.4NEIWA19906(Alcoa Primary MetalsIntalco Works;Ferndale, WA)NEIWA19906(Alcoa Primary MetalsIntalco Works;Ferndale, WA)PAHs as BaP(cancer)10911860100NEI46970(Reynolds Metals, St.Lawrence Reduction Plant;Massena, NY)NEI46970(Reynolds Metals, St.Lawrence ReductionPlant;Massena, NY)Dioxins as 2,3,7,8-TCDD(cancer)121212124020NEI32661(Alcoa Inc. – WarrickOperations;Newburgh, IN)NEI46970(Reynolds Metals, St.Lawrence ReductionPlant;Massena, NY)Notes: TPY = tons per year. SVs rounded to one significant figure. Cell shadings indicate records corresponding to SVs of 2 orhigher (i.e., the emissionsexceeded the threshold).Emissions and screening thresholdsnot shown for space purposes. Notes: N/E = notemitted. TPY = tons per year. SVs rounded toone significant figure. Cell shadings indicate recordscorresponding to SVs of 2 or higher (i.e., the emissions exceeded the threshold). Emissions and screening thresholds not shownfor space purposes.aThe emission screening threshold for mercuryapplies to emissions of divalent mercury, although EPA derived it based on hazardsassociated with ingestion of fish contaminated withmethyl mercury (i.e., emissions of divalentmercury, which transforms to methyl mercury within the environment, accumulates infish tissue, and is consumed by the fisher). Thecontribution from hazards associated ingestion of divalent mercuryfrom contaminated FFC or fish media is relatively minimal.Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 9 July 2014 

## 4. Tier 3 Emission Screening Assessment

Based on the Tier 2 SVs and other considerations with respect to the source category being assessed, EPA may conduct Tier 3 assessments on so me facilities. We discuss in this section the Tier 3 assessment conducted for NEI41217 (whose Tier 2 mercury SV was 2 for the fisher), NEIWA19906 (whose Tier 2 cadmium SV was 2 for the fisher), and NEI46970 (whose Tier 2 PAH SVs were 60 and 100 for the fisher and farmer, respectively, and whose Tier 2 dioxin SVs were 10 and 20 for fisher and farmer, respectively).



### 4.1 Lake Assessment

Other than verifying a facility’s emission rate s, one of the simplest assessments EPA can conduct (beyond the Tier 2 methods) is assessing the existence, the potential purpose, the accessibility and fishability, and the suitability of lakes for the models and methods used in Tier 2. The full USGS dataset of lakes and reservoirs nationwide that EPA uses in Tier 2 does not contain information on lake accessibility or fishabilit y. In addition, it occasionally identifies a lake that no longer exists (e.g., it has evaporated or been drained) or it uses a classification that might not accurately reflect the lake’s purpose or type. EPA uses aerial and street-view imagery and internet searches to quickly ascertain if an assessed lake actually exists, if it is probably not fished (e.g., appears swampy or covered in algae), if it is likely used for industrial or waste disposal/treatment purposes, and/or if it is adjacent to or connected to a river or saltwater body (estuaries, rivers, and saltwater areas are not ideal for the assessment models and methods).

For example, the blue outline in Figure 4-1 identifies a lake from the USGS dataset that originally qualified for Tier 2 based on the information provided in that dataset, but aerial imagery shows it is likely covered in algae or other thick plant matter. Similarly, the outline in Figure 4-2 identifies a lake that originally qualifi ed, but aerial imagery shows that it is directly adjacent to an industrial facility and likely used only for on-site industrial purposes.

For facilities undergoing the lake assessment portion of Tier 3 screening, EPA evaluates all lakes from which the fish catches and consumes fish according to the refined Tier 2 fisher methods discussed in Section 3.2. EPA permanently removes, from the screening assessment, all lakes meeting the criteria discussed in the previous paragraphs, so that they are no longer used in any screening assessment. If EPA removes a lake from the facility’s assessment, it might be necessary for the hypothetical fisher to catch and consume fish from additional lake(s) in order to fish a total of 373 acres. In this case, EPA evaluates additional lakes that were not fished, using the methods discussed in Section 3.2, in descending order of initial Tier 2 fisher SV and lake area.

If EPA removes any lakes from the screening, EPA conducts the screening again (using the Tier 2 methods) with the revised lake dataset. Although EPA conducts this additional lake assessment based on the Tier 2 SVs of a particular set of facilities, lakes removed during that assessment could affect the SVs of other faciliti es in the source category beyond that original set. This can happen if an assessed facility is within 50 km of another assessed facility, whereby removing a lake could affect the SVs of both facilities. EPA does not sum SVs across facilities.Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 10 July 2014 

### Figure 4-1. Example of Lake Removed from Screening—Likely Covered in Algae or Thick Plant Matter

Note: Aerial imagery from ESRI World Imagery (2014).



### Figure 4-2. Example of Lake Removed from Screening—Likely an Industrial Lake

Note: Aerial imagery from ESRI World Imagery (2014).Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 11 July 2014 

### 4.2 Tier 3 Lake Assessments Results for this Source Category

The information in Table 4-1 is related to the lakes evaluated in the Tier 3 screening of cadmium emissions from NEIWA19906 and dioxin and PA H emissions from NEI46970. EPA did not assess lakes in Tier 3 for NEI41217 because there were more than 70 lakes within 50 km of the facility that qualified for Tier 2 screening; while a Tier 3 lake assessment might have disqualified some of the lakes, it was still likely that the fisher would catch and consume 373 g fish/day cumulatively from the remaining lakes. As such, it was more efficient to perform a plume-rise assessment on NEI41217 prior to any potential lake assessment, as discussed in Section 4.4.

The table includes several lakes we removed during the assessment (see gray shaded rows). For lakes remaining in the screening after the lake assessment, the table contains information on how much of the subsistence fisher’s daily fish consumption came from each lake, and how much of the corresponding fisher SV was attributable to each lake. For NEIWA19906, lakes labeled RMV-3, RMV-4, and RMV-5 were on islands and EPA concluded that it was unlikely for a fisher to boat to lakes on multiple islands in one day. These island lakes were not permanently removed from future assessments, as they tec hnically still qualify for screening assessments.

Table 4-1. Results of Tier 3 Lake Assessments in this Source Category

Facil. NEI ID PB-HAP Group Lake Name Lake Area (acres) Selection Order Percent of Ingested

Fish Coming

From This Lake Percent of Tier 3 Fisher SV Attributed

To This

Lake Reason for Removal NEIWA19906 Cadmium Lake Terrell 316 1 85% 87% --

Wiser Lake 91 2 15% 13% --

Tennant Lake 44 RMV-1 -- -- Appears contaminated with algae or thick plant matter Barrett Lake 42 RMV-2 -- -- Appears to be a tiny creek Horseshoe Lake a 69 RMV-3 -- -- On an island, unlikely that fisher would boat to lakes on multiple islands in one day Spencer Lake a 67 RMV-4 -- -- On an island, unlikely that fisher would boat to lakes on multiple islands in one day Name Not Provided a 35 RMV-5 -- -- On an island, unlikely that fisher would boat to lakes on multiple islands in one day NEI46970 Dioxin St. Moses 116 1 31% 76% --

Allen Falls Reservoir 77 2 21% 9% --

Lake Titus 410 3 48% 15% --Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 12 July 2014

Facil. NEI ID PB-HAP Group Lake Name Lake Area (acres) Selection Order Percent of Ingested

Fish Coming

From This Lake Percent of Tier 3 Fisher SV Attributed

To This

Lake Reason for Removal Name Not Provided 109 RMV-1 -- -- Appears to be creek that sometimes swells (hasn't looked like a lake since the 1990s)
PAH St. Moses 116 1 31% 80% --

Allen Falls Reservoir 77 2 21% 8% --

Lake Titus 410 3 48% 13% --

Name Not Provided 109 RMV-1 -- -- Appears to be creek that sometimes swells (hasn't looked like a lake since the 1990s)
Notes: The lakes shown in this table, and their corresponding select ion order and percentages of ingestion and SV, are related only to the indicated facilities and PB-HAP group emissions . For other PB-HAP groups emitted by thes e facilities, the fisher might fish a different set of lakes and/or wi th a different selection order. “RMV” indicates that we removed the lake during Tier 3. Th e number beside the “RMV” designati on was for map labeling purposes (see the figure in this subsection). The percentages of ingestion and SV reflect the a ssessment after we removed this lake.

a These island lakes were not permanently removed from future assessments, as they technically still qualify for screening assessments.



### Figure 4-3 and Figure 4-4 are aerial images delineating the NEIWA19906 and NEI46970 lakes, respectively, in Table 4-1. The labels of the lakes in the map correspond to the data in the “Selection Order” column of the table. Lakes labeled in the map with negative numbers (e.g., -1, -2, and so on) are qualifying lakes that the fisher did not fish because the fish ingestion rate was already met by fishing the first set of lakes (i.e., by fishing those labeled 1, 2, and so on). The maps are focused on the fished and removed lakes, so they might not show all unfished lakes.

As discussed in Section 3.4, NEIWA19906’s cadmium emissions exceeded the Tier 2 fisher threshold by approximately a factor of 2. Removing five lakes from this facility’s screening did not effectively decrease its fisher SV. NEI46970’s PAH emissions exceeded the Tier 2 fisher and farmer thresholds respectively by approximate factors of 60 and 100, and NEI46970’s dioxin emissions exceeded the Tier 2 fisher and fa rmer thresholds respectively by approximate factors of 10 and 20. Removing one lake from this facility’s screening did not effectivelydecrease its PAH and dioxin SVs. As discussed in Sections 4.3 and 4.4, we conducted a plumerise assessment on these emissions and on mercury emissions from NEI41217.Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 13 July 2014 

### Figure 4-3. Lakes Assessed for Cadmium Emissions at NEIWA19906

Notes: Aerial imagery from ESRI (2014). Lake labels correspond to the “Selection Order” column in Table 4-1. The “lake” shown in Figure 4-1 corresponds to “RMV-1” here. Lake labels using negative numbers ar e not shown in Table 4-1—those are qualifying lakes that the fisher did not fish because the fished lakes altogether met the fish ingestion rate. Not all of the unfished lakes are shown.



### Figure 4-4. Lakes Assessed for PAH and Dioxin Emissions at NEI46970

Notes: Aerial imagery from ESRI (2014). Lake labels correspond to the “Selection Order” column in Table 4-1. Lake label s using negative numbers are not shown in Table 4-1—those are qualifying lakes that t he fisher did not fi sh because the fished lakes altogether met the fish ingestion rate.Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 14 July 2014 

### 4.3 Plume-rise Assessment

In Tiers 1 and 2, all chemicals are emitted inside the mixing layer and are available for groundlevel exposure. In reality, the physical height of an emission source, in combination with the temperature and velocity of the chemical plume as it leaves the source, can cause some of the chemical plume to reach areas above the mixing layer. In TRIM.FaTE modeling, the chemical mass deposited above the mixing layer (i.e., the model’s upper-air layer) is unavailable for ground-level exposure (i.e., the upper-air layer func tions as a chemical sink). Many emission sources in RTR are physically taller than the mixing height during some hours, and hot exit gas temperatures (i.e., buoyancy) and/or high exit gas velocities (i.e., momentum) can further elevate the chemical plume.

EPA uses methods summarized by Seinfeld and Pandi s (1998) to estimate how often a facility’s emissions reach the upper-air sink, which decreases availability for ground-level exposure. The methods to estimate the amount of chemical lost to the upper-air sink require use of the facility’s corresponding meteorology data (e.g., air temperature and vertical temperature gradient, wind speed, and atmospheric stability), the mass of the PB-HAP emitted from each source, the physical characteristics of the sources (i.e., release height, inside diameter at the release point, and exit gas temperature and velocity), and an estimate of the size of the facility.

For each relevant emission source, EPA estimates the hourly effective release height (i.e., sum of actual release height and plume rise) and compares it to the hourly mixing height to determine the mass of chemical remaining in the mixing layer. EPA compares the mass of chemical remaining in the mixing layer, summed across the sources, to the total emitted mass of the chemical. This results in an adjustment factor expressing the fraction of emissions remaining in the mixing layer after accounting for release height and plume rise. EPA applies this final plume-rise adjustment factor to the Tier 2 SVs.


### 4.4 Tier 3 Plume-rise Assessment Results for this Source Category

The Tier 3 lake assessment did not effectively lower the fisher SVs for cadmium emissions from NEIWA19906 or for PAH and dioxin emissions fr om NEI46970 (see Section 4.2). We conducted a plume-rise assessment on these emissions. We also conducted a plume-rise assessment on mercury emissions from NEI41217, which exceeded the Tier 2 fisher threshold by a factor of 2 and which had more than 70 lakes, making a Tier 3 plume rise assessment a more efficient than a Tier 3 lake assessment. Table 4-2 contains information on these emissions and the physical characteristics of each unique emission source, al ong with the fraction of emitted chemical from each source that remained in the mixing layer (i.e., is not deposited into the upper-air sink). For these purposes, we define a unique emission source as having a unique combination of physical characteristics (i.e., height, diameter, te mperature, and velocity), though in some cases we grouped together sources with roughly similar physical characteristics. We show in the last column the total fraction of emissions from all sources together that remained in the mixing layer. We calculated this value by weighting the value in the previous column (fraction remaining in the mixing layer, by source) by the fraction of mercury emissions coming from each source (i.e., the third column), and summing those weighted values. To account for these plume-rise data, we scaled the Tier 2 SVs by the fractions shown in the last column.Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 15 July 2014 

### Table 4-2. Results of Tier 3 Plume-rise Assessments in this Source Category

Facil. NEI ID Source Num. Fraction of Emiss. From This Source a Physical Characteristics of Emiss. Source Fraction of Emiss. Remaining in Mixing Layer

Height

(m) Exit Gas Temp.

(K) Inside Diameter (m) Exit Gas Vel. (m/s) By Source Facility Total NEIWA19906 (Cadmium emissions) 1 0.97 16.5 289 4.2 4.0 0.67 0.67

2 0.03 25.6 370 6.1 15.9 0.52
NEI41217 (Mercury emissions) 1 0.70 22.5 295 0.0009 0.000009 0.99 0.94

2 0.21 61.0 353 3.2 23.5 0.80

3 0.09 61.3 353 1.4 26.4 0.84

4 0.01 48.5 322 1.1 19.5 0.90
NEI46970 (Dioxin emissions) 1 0.94 14.9 303 0. 0009 0.00009 1.00 0.99

2 0.06 44.5 305 7.5 11.3 0.77
NEI46970 (PAH emissions) 1 0.98 14.9 303 0. 0009 0.00009 1.00 0.99

2 0.02 44.5 305 7.5 11.3 0.77

a We normalized PAH and dioxin emissions to BaP and 2,3,7,8-TC DD, respectively, for oral toxicity and Tier 2 modeled environmental fate and transport.



### Table 4-3 contains the previously calculated Tier 2 SVs for the emissions screened in Tier 3 (reflecting the assessment described in Section 3), along with the SVs after the Tier 3 lake and plume-rise assessments. For cadmium emissions from NEIWA19906, while the Tier 3 lake assessments alone did not effectively decrease the SVs, the combined effect of the lake and plume-rise assessments was a decrease in the fisher and farmer SVs from 2 to 1 and from 0.4 to 0.3, respectively. The Tier 3 plume-rise assessment decreased the mercury fisher SV at NEI41217 from 2 to 1. The combined lake and plume-rise assessments did not effectively lower dioxin and PAH SVs related to NEI46970.

Because these cadmium and mercury emission screened out in Tier 3, and because the PAH and dioxin SVs for the fisher were below 100, we did not conduct any other Tier 3 screening assessments. The farmer SV of 100 for PAH emissions from NEI46970 is of less concern because of the assumptions made about the farmer scenario in the screening assessments. The screening evaluates hypothetical farm areas at a fixed distance in all compass directions around the facility. EPA does not validate these modeled farm locations nor the types and amounts of crops grown and livestock raised. EPA assumes the farms are there and that they produce all the assessed foodstuffs in the amounts necessary for the evaluated subsistence ingestion rates.Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 16 July 2014



### Table 4-3. Tier 3 SVs Before and After Additional Lake and Plume-rise Assessments in this Source Category

Facil. NEI ID Facil. Name Facil. City Facil. State SVs a

Before Tier 3 Assessments After Tier 3 Lake Assessments Afte r Tier 3 Lake AND Plume-rise Assessments

Fisher Farmer Fisher Farmer Fisher Farmer NEIWA19906 (Cadmium emissions) Alcoa Primary Metal Intalco Works Ferndale WA 2 0.4 2 0.4 1 0.3

NEI41217 (Mercury emissions) Alumax of South Carolina Goose Creek SC 2 0.0003 (Assessment not performed) (Assessment not performed) 1 0.0003

NEI46970 (Dioxin emissions) Reynolds Metals, St. Lawrence Reduction Plant Massena NY 10 20 10 20 10 20

NEI46970 (PAH emissions) Reynolds Metals, St. Lawrence Reduction Plant Massena NY 60 100 60 100 60 100

a SVs rounded to one significant figure. Cell s hadings indicate SVs of 2 or higher (i.e ., the emissions exceeded the threshold).



## 5. Comparison to Tier 1 Screeni ng Results for this Source Category

In Table 5-1, we present a high-level comparison between the Tier 1 SVs and Tier 3 SVs. The Tier 3 SVs reflect the Tier 3 screening of some emissions from three facilities; otherwise, the Tier 3 SVs are unchanged from the Tier 2 screening. The remainder of this section provides an overview of the results for each of the four PB-HAPs.

 

### Mercury:

– Emissions at nine facilities exceeded the Tier 1 threshold but screened out in Tier 3.

– The highest Tier 3 fisher and farmer SVs were respectively approximately 10 timesand 12,500 times lower than the highest Tier 1 SV (which combined fish- and FFCrelated exposure).

– When the highest Tier 3 fisher SV was combined with the highest Tier 3 farmer SV (to directly compare to the highest Tier 1 SV), the combined Tier 3 SV was approximately 10 times lower (not shown in the table). This is because nearly all mercury exposure occurs through fish ingestion.

 

### Cadmium:

– Emissions at six facilities exceeded the Tier 1 threshold but screened out in Tier 3.

– The highest Tier 3 fisher and farmer SVs were respectively approximately 30 timesand 100 times lower than the highest Tier 1 SV (which combined fish- and FFCrelated exposure).Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 17 July 2014 

### – When the highest Tier 3 fisher SV was combined with the highest Tier 3 farmer SV (to directly compare to the highest Tier 1 SV), the combined Tier 3 SV was approximately 20 times lower than the Tier 1 SV (not shown in the table). This is because nearly all cadmium exposure occurs through fish ingestion.

 

### PAHs:

– Emissions at all 13 facilities exceeded the Tier 1 threshold, but three screened out for the Tier 3 fisher and four screened out for the Tier 3 farmer.

– The highest Tier 3 fisher and farmer SVs were respectively approximately 30 times and 20 times lower than the highest Tier 1 SV (which combined fish- and FFC-related exposure).

– When the highest Tier 3 fisher SV was combined with the highest Tier 3 farmer SV (to directly compare to the highest Tier 1 SV), the combined Tier 3 SV was approximately 10 times lower than the highest Tier 1 SV (not shown in the table).

 

### Dioxins:

– Emissions at all 13 facilities exceeded the Tier 1 threshold, but one screened out for the Tier 3 fisher and one screened out for the Tier 3 farmer.

– The highest Tier 3 fisher and farmer SVs were respectively approximately five times and 10 times lower than the highest Tier 1 SV (which combined fish- and FFC-related exposure).

– When the highest Tier 3 fisher SV was combined with the highest Tier 3 farmer SV (to directly compare to the highest Tier 1 SV), the combined Tier 3 SV was approximately three times lower than the highest Tier 1 SV (not shown in the table).

 

### PAHs + Dioxins:

– The facility-level sum of PAH and dioxin SVs was 20 or higher at all 13 facilities in Tier 1 (with 12 facilities at 100 or higher), 5 or higher at all 13 facilities for the Tier 3 fisher (all lower than 100), and 5 or higher at 12 facilities for the Tier 3 farmer (one 100 or higher). This is not shown in the table.Human Health Multipathway Residual Risk Screening Assessment for the Primary Aluminum Production Source Category

Draft 18 July 2014 

### Table 5-1. Comparison of Tier 1 and Tier 3 Screening Results for this Source Category

PB-HAP Group Num. Facil. Exceeding Threshold Highest SV Tier 1, Combined Fisher and Farmer Tier 3, Fisher Tier 3, Farmer Tier 1, Combined Fisher and Farmer Tier 3, Fisher Tier 3, Farmer Mercury a (non-cancer) 9 0 0 10 1 0.0008

Cadmium (non-cancer) 6 0 0 30 1 0.3

PAHs as BaP (cancer) 13 10 9 2,000 60 100

Dioxins as 2,3,7,8-TCDD (cancer) 13 12 12 200 40 20

Notes: N/E = not emitted. SVs rounded to one significant figure. Cell shadings indicate records corresponding to SVs of 2 or hi gher (i.e., the emissions exceeded the Tier 1 threshold). Emissions and screening thre sholds not shown for space purposes.

a The emission screening threshold for mercury applies to emissions of divalent merc ury, although EPA derived it based on hazards associated with ingestion of fish contaminat ed with methyl mercury (i.e., emissions of divalent mercury, which transforms to me thyl mercury within the environment, accumulates in fish tissue, and is consumed by the fisher). The contribution from hazards associated ingestion of divalent mercury from contam inated FFC or fish media is relatively minimal.



## 6. References

ESRI (Environmental Systems Research Instit ute). 2014. World Imagery. Accessed July 9, 2014. Available at: http://www.arcgis.com/home/item.html?id=10df2279f9684e4a9f6a7f08febac2a9

. Seinfeld, J.H., and S.N. Pandis. 1998. Atmospheric Chemistry and Physics: From Air Pollution to Climate Change, Wiley-Interscience, New York, pp. 931–933.