### Appendix 9

Technical Support Document: Human Health Multipathway Residual Risk Screening Assessment for the Phosphate Fertilizer Production and Phosphoric Acid Manufacturing Source Categories

## Technical Support Document: Huma n Health Multipathway Residual Risk Screening Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

REVISED DRAFT

July 7, 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 Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft iii July 2014 

## CONTENTS

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

Figures ....................................................................................................................... .................. iv

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

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

2.1 Tier 1 Emission Screening Results for these Source Categories ................................ 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 ................................................................. 7

3.4 Tier 2 Screening Results for these Source Categories ............................................... 7

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

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

4.2 Tier 3 Lake Assessments Results for these Source Categories ............................... 11

4.3 Plume-rise Assessment ............................................................................................. 12

4.4 Tier 3 Plume-rise Assessment Results for these Source Categories ........................ 13

4.5 Assessment of Time-series Meteorology and Effective Release Heights ...................................................................................................................... 14

4.6 Tier 3 Time-series Assessment Results for these Source Categories ...................... 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 these Source Categories ................................ 4
Table 3-1. Tier 2 Screening Results for these Source Categories ................................................ 8
Table 4-1. Results of Tier 3 Lake Assessments for Mercury Emissions ..................................... 11
Table 4-2. Results of Tier 3 Plume-rise Assessments for Mercury Emissions ............................ 13

Table 4-3. Tier 3 SVs Before and After Additional Lake and Plume-rise Assessments ........................................................................................................ 14

Table 4-4. Tier 3 Fisher SVs Before and After Time-series Assessments .................................. 16
Table 5-1. Comparison of Tier 1 and Tier 3 Screening Results for these Source Categories ............................................................................................................ 17Human Health Multipathway Residual Risk Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft iv July 2014 

## FIGURES Figure 4-1. Example of Lake Removed from Screening—Likely Evaporated or Drained ................................................................................................................. 10
Figure 4-2. Example of Lake Removed from Screening—Likely an Industrial Lake ................... 10
Figure 4-3. Lakes Assessed for NEIMS059305 (Phosphate Fertilizers Production Source Category) ................................................................................................. 12
Figure 4-4. The Modeling Spatial Scenario Used for the Unnamed Lake and for “Crane Lakes” ....................................................................................................... 15
Figure 4-5. The Modeling Spatial Scenario Used for “Black Creek Cooling Pond” ..................... 15Human Health Multipathway Residual Risk Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

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 phosphate fertilizers production facilities and phosphoric acid manufacturing 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 ca n be found in Appendix 5 of the Risk Report. 1 Where appropriate, this discussion 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 phosphate fertilizers production source category and the phosphoric acid manufacturing source category by comparing PB-HAP emissions from facilities within the source categories to the thresholds. We use the term “screening values” (SVs) to refer to the ratio of a facility’s emissions of a PB-HAP

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 Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 2 July 2014 to that PB-HAP’s threshold. When rounded to one significant figure, an SV of 1 or smaller 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 greater indicates that the emissions exceeded the threshold and potentially pose health risks above levels of concern.

The phosphate fertilizers production source category contains 11 facilities, and the phosphoric acid manufacturing source category contains 12 facilities. As described in this report, most emissions of the evaluated PB-HAPs screened out in the Tier 1 assessment. For the phosphoric acid manufacturing source category, one facility’s cadmium and mercury emissions exceeded their respective Tier 1 thresholds but screened out in the Tier 2 assessment. For the phosphate fertilizers production source category, one facility’s mercury emissions exceeded the Tier 1 threshold, but the emissions screened out in Tier 3, which included additional assessments of its emissions and corresponding meteorology and lake data.

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 3-1 (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 (Section s 1.1 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 to 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.)Human Health Multipathway Residual Risk Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 3 July 2014 

### 2.1 Tier 1 Emission Screening Re sults for these Source Categories

As shown in Table 3-1, emissions of dioxins and PAHs (emitted by one facility in the phosphoric acid manufacturing source category) screened out because the emissions were approximately a factor of 5 below the respective thresholds.

In the phosphate fertilizers production source category, cadmium emissions screened out. Mercury emissions exceeded the threshold by approximately a factor of 20 at one (out of 11) mercury-emitting facilities. This facility was NEIMS059305, a Mississippi Phosphates Corp. facility in Pascagoula, MS.

In the phosphoric acid manufacturing source category, cadmium and mercury emissions exceeded their respective thresholds by approximately factors of 2 and 7, respectively, at one (out of 12) facilities emitting cadmium and mercury. This facility was NEI45571, a PCS Phosphates Co. facility in Aurora, NC. PAH and dioxin emissions screened out. When PAH anddioxin SVs were summed together per facility (i.e., calculating the total PAH+dioxin screeninglevel potential cancer risk), the highest total “cancer SV” was 0.4 and screened out (not shown in table).


## 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 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.

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 Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 4 July 2014 Table 3-1. Tier 1 Emission Screening Results for these Source Categories

Source Cat. PB-HAP Group (a) Num. Facil. Exceeding Threshold (b) Largest

SV [(d)/(e)] (c) Facil. with Largest SV (d) Emiss. at Facil. with

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

Thresh.

(TPY)
Phosphate Fertilizers Production Mercury b (non-cancer) 1 20 NEIMS059305 (Mississippi Phosphates Corp.; Pascagoula, MS) 6.74E-03 3.16E-04

Cadmium (non-cancer) 0 0.9 NEIMS059305 (Mississippi Phosphates Corp.; Pascagoula, MS) 1.11E-02 1.18E-02

PAHs as BaP (cancer) N/E N/E N/E N/E 2.58E-03

Dioxins as 2,3,7,8-TCDD (cancer) N/E N/E N/E N/E 2.81E-09

Phosphoric Acid Manufacturing Mercury b (non-cancer) 1 7 NEI45571 (PCS Phosphate Co. Inc. - Aurora; Aurora, NC) 2.23E-03 3.16E-04

Cadmium (non-cancer) 1 2 NEI45571 (PCS Phosphate Co. Inc. - Aurora; Aurora, NC) 2.13E-02 1.18E-02

PAHs as BaP (cancer) 0 0.2 NEI45571 (PCS Phosphate Co. Inc. - Aurora; Aurora, NC) 5.54E-04 2.58E-03

Dioxins as 2,3,7,8-TCDD (cancer) 0 0.2 NEI45571 (PCS Phosphate Co. Inc. - Aurora; Aurora, NC) 5.63E-10 2.81E-09

Notes: N/E = not emitted. TPY = tons per year. SVs rounded to one significant figure. Cell shadi ngs indicate records correspond ing
t o SVs of 2 or greater (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

a ssociated with ingestion of fish contaminated with methyl mercury (i.e., emissions of di valent mercury, which transforms to met hyl mercury within the environment, accumulates in fish tissue, and is consumed by the fisher). The contribution from hazards

a ssociated ingestion of divalent mercury from contam inated FFC or fish media is relatively minimal.



### 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 toHuman Health Multipathway Residual Risk Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 5 July 2014 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.

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

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 Attachm ent E) for additional information on lake productivity.Human Health Multipathway Residual Risk Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 6 July 2014 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.

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.

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 Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 7 July 2014 

### 3.3 Finalizing Tier 2 Fa rmer Screening Values

For a given PB-HAP group emitted by a facility, EPA identifies the largest 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 these Source Categories

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 largest Tier 2 farmer SVs (discussed in Section 3.3).

As shown in Table 3-2, all emissions screened out except for mercury emissions from NEIMS059305 (phosphate fertilizers production source category). The fisher SV at that facility was 3, while the farmer SV was 0.002. Mercury and cadmium emissions from NEI45571 (phosphoric acid production source category), which exceeded their respective Tier 1 thresholds by factors of 7 and 2, screened out in Tier 2—its mercury and cadmium Tier 2 fisher SVs were 1 and 0.3, respectively, and the Tier 2 farmer SVs were 0.0007 and 0.02, respectively.

When PAH and dioxin SVs were summed together per facility in the phosphoric acid manufacturing source category (i.e., calculating the total PAH+dioxin screening-level potential cancer risk), the highest total “cancer SVs” screened out (SV = 0.04 for fisher, 0.07 for farmer; not shown in table).Human Health Multipathway Residual Risk Screening Assessment for the Phosphate FertilizersProduction and Phosphoric Acid Manufacturing Source CategoriesDraft 8 July 2014Table 3-2. Tier 2 Screening Results for these Source CategoriesFacil. TypePB-HAPGroupNum. Facil.ExceedingFisherThresholdNum. Facil.ExceedingFarmerThresholdNum. Facil. ExceedingThreshold,Either Fisher or Farmer,Both Fisher and FarmerLargestFisher SVLargestFarmerSVFacil. with LargestFisher SVFacil. with LargestFarmer SVPhosphateFertilizersProductionMercurya(non-cancer)11103 0.002NEIMS059305(MississippiPhosphates Corp.;Pascagoula, MS)NEIMS059305(Mississippi PhosphatesCorp.;Pascagoula, MS)Cadmium(non-cancer)0 0000.1 0.008 NEIMS059305(MississippiPhosphates Corp.;Pascagoula, MS)NEIMS059305(Mississippi PhosphatesCorp.;Pascagoula, MS)PAHs as BaP(cancer)N/E N/E N/E N/E N/E N/E N/EDioxins as2,3,7,8-TCDD(cancer)N/E N/E N/E N/E N/E N/E N/EPhosphoricAcidManufacturingMercurya(non-cancer)0 0001 0.0007 NEI45571(PCS Phosphate Co.Inc. - Aurora;Aurora, NC)NEI45571(PCS Phosphate Co. Inc. -Aurora;Aurora, NC)Cadmium(non-cancer)0 0000.3 0.02 NEI45571(PCS Phosphate Co.Inc. - Aurora;Aurora, NC)NEI45571(PCS Phosphate Co. Inc. -Aurora;Aurora, NC)PAHs as BaP(cancer)0 0000.01 0.06 NEI45571(PCS Phosphate Co.Inc. - Aurora;Aurora, NC)NEI45571(PCS Phosphate Co. Inc. -Aurora;Aurora, NC)Dioxins as2,3,7,8-TCDD(cancer)0 0000.03 0.01 NEI45571(PCS Phosphate Co.Inc. - Aurora;Aurora, NC)NEI45571(PCS Phosphate Co. Inc. -Aurora;Aurora, NC)Notes: N/E = not emitted. TPY = tons per year. SVs rounded toone significant figure. Cell shadings indicate records corresponding to SVs of 2 or greater (i.e., the emissions exceededthe threshold). Emissionsand screening thresholds notshown for 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 Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

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 mercury hazards for NEIMS059305 in the phosphate fertilizers production source category, whose Tier 2 fisher SV for mercury was 3.



### 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 evaporated or drained. Similarly, the outline in Figure 4-2 identifies a lake that originally qualified, but aerial imagery s hows that it is directly adjacent to an industrial facility and likely used only for on-site industrial purposes.

For facilities undergoing Tier 3 screening, EPA evaluat es 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 Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 10 July 2014 Figure 4-1. Example of Lake Removed from Screening—Likely Evaporated or Drained

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 Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 11 July 2014 

### 4.2 Tier 3 Lake Assessments Resu lts for these Source Categories

The information in Table 4-1 is related to the lakes evaluated in the screening of NEIMS059305 in the phosphate fertilizers production source category. The table includes one lake we removed during the assessment (see gray shaded row). 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.

Table 4-1. Results of Tier 3 Lake Assessments for Mercury Emissions

Facil. NEI ID 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 NEIMS059305 (phosphate fertilizers production source category) Name Not Provided 49 1 9% 16% --

Crane Lakes 82 2 10% 14% --
Black Creek Cooling Pond a 59 3 81% 70% --

Presley Pond 30 RMV-1 -- -- Evaporated or drained

Notes: The lakes shown in this table, and their corresponding select ion order and percentages of ingestion and SV, are related only to the mercury emissions from this facility. For other PB-HAP groups emitted by this facility, the fisher might fish a different set o f lakes and/or with 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 Black Creek Cooling Pond appears to have been created by a da m and, despite its name, we found no reliable information suggesting it is restricted acce ss, unfishable, or industrial.
Figure 4-3 is an aerial image delineating the lakes 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 map is focused on the fished and removed lakes, so it does not show all unfished lakes. Table 4-1, for space purposes, does not contain information on these unfished lakes. NEIMS059305 is close to the Gulf of Mexico and has many water bodies of varying types within 50 km; the red outlines and text in the map call attention to water bodies within the map extent that did not qualify for the Tier 2 because they appeared to be estuarine.

As discussed in Section 3.4, this facility’s me rcury emissions exceeded the Tier 2 thresholds for fishers by approximately a factor of 3. Removi ng one lake from this facility’s screening did not effectively decrease its Tier 3 fisher SV, so we conducted a plume-rise assessment on the mercury emissions, as discussed in Sections 4.3 and 4.4.Human Health Multipathway Residual Risk Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 12 July 2014 Figure 4-3. Lakes Assessed for NEIMS059305 (Phosphate Fertilizers Production Source Category)

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.



### 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’sHuman Health Multipathway Residual Risk Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 13 July 2014 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 R esults for these Source Categories

The Tier 3 lake assessment did not effectively lower the Tier 3 fisher SV for mercury emissions from NEIMS059305 (phosphate fertilizers production source category; see Section 4.2). We also conducted a plume-rise assessment on the emissions. Table 4-2 contains information on the mercury emissions and physical characterist ics of each unique emission source, along with the fraction of mercury emitted from each source that remained in the mixing layer (i.e., is not deposited into the upper-air sink). 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 fisher and farmer SVs by the fractions shown in the last column.

Table 4-2. Results of Tier 3 Plume-rise Assessments for Mercury Emissions

Facil. NEI ID Source Num. Fraction of Emiss. From This

Source 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 NEIMS059305 (phosphate fertilizers production source category) 1 0.0121 24.7 350 1.8 13.1 0.806 0.7679

2 0.9879 48.8 355 1.8 12.5 0.7675

Table 4-3 contains the previously calculated Tier 2 SVs for mercury (reflecting the assessment described in Section 3), along with the SVs after the Tier 3 lake and plume-rise assessments, for NEIMS059305 (phosphate fertilizers production source category).

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 SVs from 3 to 2 for the fisher scenario, and from 0.002 to 0.001 for the farmer scenario. The mercury emissions still exceeded the threshold for the fisher scenario. These assessments did not impact SVs at any other facilities in the phosphate fertilizers pr oduction or phosphoric acid manufacturing source categories. We discuss in Sections 4.5 and 4.6 an additional assessment that we conducted on the emissions using time-series meteorology and release-height data.Human Health Multipathway Residual Risk Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 14 July 2014 Table 4-3. Tier 3 SVs Before and After Additional Lake and Plume-rise Assessments

Facil. NEI ID Facil. Name Facil. City Facil

. State Tier 2 and Tier 3 Mercury SV a

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

Fisher Farme

r Fishe

r Farme

r Fishe

r Farme

r NEIMS059305 (phosphate fertilizers production source category) Mississippi Phosphate s Corp. Pascagoula MS 3 0.002 3 0.002 2 0.001

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



### 4.5 Assessment of Time-series Meteor ology and Effective Release Heights

As discussed in Section 3, EPA bases the Tier 2 SVs on the average meteorological conditions prevailing at the facility being assessed. The use of time-series meteorology data, which captures hour-by-hour changes in each of the assessed meteorological parameters instead of using constant average values, increases the accuracy of the estimates of potential risk by accounting for potential statistical interacti ons between the meteorology parameters and by improving the method of accounting for mass advected into the modeling domain.

EPA also bases Tier 2 SVs on a constant emission release height that is always within the mixing layer. Including hourly effective release heights (discussed in Sections 4.3 and 4.4) along with hourly meteorology data further increases the accuracy of the estimates of potential risk.

For a facility undergoing a time-series assessm ent, EPA develops a time series of hourly effective release heights for sources emitting the assessed PB-HAP, and EPA identifies the Tier 2 spatial scenario that best matches each lake from which the hypothetical fisher catches and consumes fish. Using this data along with the facility’s matching hourly meteorology data, the facility’s emission rates, and the subsistence ingestion rates, EPA models chemical fate and transport in TRIM.FaTE and calculates the corresponding screening-level risks using MIRC. This modeling results in a screening-level risk va lue for each lake, corresponding to ingestion of fish exposed to the evaluated PB-HAP. If the farm er scenario is specifically being assessed, the modeling will also result in a screening-level risk value for each farm. EPA multiplies the screening-level risk associated with each lake by the percent of daily ingested fish caught from the lake (see Sections 3.2 and 4.2); summing those products across all modeled lakes results in the screening-level fisher risk (i.e., fisher SV) associated with the evaluated PB-HAP emitted by the facility. The time-series-adjusted Tier 3 SVs are compared to the Tier 2 SVs calculated previously.



### 4.6 Tier 3 Time-series Assessment Results for these Source Categories

In order to account for the potential effects on exposure and risk modeling from using timeseries meteorology and effective release heights in TRIM.FaTE, we ran TRIM.FaTE three times, corresponding to each of the three assessed lakes for the mercury assessment for NEIMS059305 (phosphate fertilizers production source category). We used the “lake at 10 km” spatial scenario, shown in Figure 4-4, to model concentrations in the unnamed lake and Crane Lakes (see Table 4-1). In reality, these two lakes were respectively 12 and 19 km from the facility. We used the “lake at 20 km” spatial scenario, shown in Figure 4-5, to model concentrations in Black Creek Cooling Pond (see Table 4-1), which in reality was 23 km from the facility.Human Health Multipathway Residual Risk Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 15 July 2014 Figure 4-4. The Modeling Spatial Scenario Used for the Unnamed Lake and for “Crane Lakes”

Notes: Labels = surface parcel names for modeling. Shadings = ground cover type for modeling. Arrows within scenario = direction of runoff and erosion.

Figure 4-5. The Modeling Spatial Scenario Used for “Black Creek Cooling Pond”

Notes: Labels = surface parcel names for modeling. Shadings = ground cover type for modeling. Arrows within scenario = direction of runoff and erosion.Human Health Multipathway Residual Risk Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 16 July 2014 Table 4-4 contains the Tier 3 fisher SVs for mercury emissions from NEIMS059305 (phosphate fertilizers production source category), both before and after the time-series assessments. Both SVs reflect the Tier 3 lake assessments (see Section 4.2) but not the plume-rise assessments (see Section 4.4); this is because the time-series assessment includes chemical loss due to plume rise into the upper-air sink. Beside the previous results, the table contains the fisher SV after the time-series assessments. We did not assess farmer SVs with these time-series runs. The time-series assessments decreased the fisher SV to below levels of concern (i.e., the emissions screened out).

Table 4-4. Tier 3 Fisher SVs Before and After Time-series Assessments

Facil. NEI ID Facil. Name Facil. City Facil. State Tier 3 Mercury Fishe r SV aBefore Tier 3 Timeseries Assessments Afte r Tier 3 Timeseries Assessments
NEIMS059305 (phosphate fertilizers production source category) Mississippi Phosphates Corp. Pascagoula MS 3 1

a SVs rounded to one significant figure. Cell s hadings indicate SVs of 2 or greater (i .e., the emissions exceeded the threshold). We only assessed the fisher scenario during the time-series assessments.



## 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 mercury emissions from one facility; 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 one facility in each source category exceeded the Tier 1 threshold but screened out in Tier 3.

– The largest Tier 3 fisher and farmer SVs were respectively approximately 20 timesand 20,000 times smaller than the largest Tier 1 SV (which combined fish- and FFCrelated exposure).

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

 Cadmium:

– Emissions at one phosphoric acid manufacturing facility exceeded the Tier 1 threshold but screened out in Tier 3.

– The largest Tier 3 fisher and farmer SVs were respectively approximately nine timesand 100 times smaller than the largest Tier 1 SV (which combined fish- and FFCrelated exposure).

– When the largest Tier 3 fisher SV was combined with the largest Tier 3 farmer SV (to directly compare to the largest Tier 1 SV), the combined Tier 3 SV was approximately three times smaller than the Tier 1 SV (not shown in the table). This is because nearly all cadmium exposure occurs through fish ingestion.Human Health Multipathway Residual Risk Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 17 July 2014  PAHs:

– All emissions screened out.

– The largest Tier 3 fisher and farmer SVs were respectively approximately 20 timesand three times smaller than the largest Tier 1 SV (which combined fish- and FFCrelated exposure).

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

 Dioxins:

– All emissions screened out.

– The largest Tier 3 fisher and farmer SVs we re respectively approximately seven timesand 20 times smaller than the largest Tier 1 SV (which combined fish- and FFCrelated exposure).

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

 PAHs + Dioxins:

– The facility-level sum of PAH and dioxin SVs screened out in all screening assessments (not shown in table).
Table 5-1. Comparison of Tier 1 and Tier 3 Screening Results for these Source Categories

Source Cat. PB-HAP Group Num. Facil. Exceeding Threshold Largest 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
Phosphate Fertilizers Production Mercury a (non-cancer) 1 0 0 20 1 0.001

Cadmium (non-cancer) 0 0 0 0.9 0.1 0.008

PAHs as BaP (cancer) N/E N/E N/E N/E N/E N/E

Dioxins as 2,3,7,8-TCDD (cancer) N/E N/E N/E N/E N/E N/E

Phosphoric Acid Manufacturing Mercury a (non-cancer) 1 N/E N/E 7 1 0.0007

Cadmium (non-cancer) 1 N/E N/E 2 0.3 0.02

PAHs as BaP (cancer) 0 0 0 0.2 0.01 0.06

Dioxins as 2,3,7,8-TCDD (cancer) 0 0 0 0.2 0.03 0.01

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

a The emission screening threshold for mercur y applies to emissions of divalent mercury, although EPA derived it based on hazards associated with ingestion of fish c ontaminated with methyl mercury (i.e., emissi ons of divalent mercury, which transfor ms to methyl mercury within the environment, accumulates in fish tissue, and is consumed by the fi sher). The contribution from hazards associated ingestion of divalent mercury from contaminated FFC or fish media is relatively minimal.Human Health Multipathway Residual Risk Screen ing Assessment for the Phosphate Fertilizers Production and Phosphoric Acid Manufacturing Source Categories

Draft 18 July 2014 

## 6. References

ESRI (Environmental Systems Research Instit ute). 2014. World Imagery. Accessed June 12, 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.