Appendix 8

Acute Noncancer Risk Analysis for Phosphate Fertilizer and Phosphoric Acid 

Manufacturing
Acute Modeling Approach

Initial acute screening risk calculations were performed with the HEM-3 model. 

HEM-3 estimates acute (1-hour) impacts at both polar and census block receptors, refer 

to Table 1. It is assumed for this short period of time that an exposed individual could be 

located at any off-site location. The lack of readily available detailed property boundary 

information for many of the facilities evaluated made it difficult to determine whether 

receptors were on- or off-site. In the absence of such information, the first ring of polar 

receptors was placed 100 meters from the plant center for many facilities. However, 

these polar rings often transected on-site locations, restricting public access to exposures 

at these levels and thereby overestimating exposures.

The screening approach used by HEM-3 to estimate maximum 1-hour exposures 

also likely overestimates. To estimate maximum 1-hour concentrations at each receptor, 

HEM-3 sums the maximum concentrations attributed to each source, regardless of 

whether those maximum concentrations occurred during the same hour. In other words, 

HEM-3 assumes that the maximum impact from each source at each receptor occurs at 

the same time. In actuality, maximum impacts from different sources may occur at 

different times. 

This appendix includes the results of refined acute assessments performed for 

facilities that exceeded short-term health benchmarks using the HEM-3 approach, refer to 

Table 2. The refinements can address both areas of conservatism described above. The 

simplest refinement is to plot the HEM-3 polar grid results on aerial photographs of the 

facilities; This allows the assessment of off-site locations that may be accessible to the 

public (e.g., roadways and public buildings.). In cases where this refinement results in 

lower acute risks no further refinement was conducted. However, if acute risk still 

remain at or near levels of concern a further refinement is conducted. This second 

refinement includes remodeling with the AERMOD model directly (instead of using 

HEM) to estimate maximum 1-hour concentrations at each receptor by pairing individual 

source impacts in time and space. The AERMOD results are then plotted on aerial 

photographs as noted above to determine off-site impacts. Modeling with AERMOD 

also allows the estimation of the frequency of higher impacts at or above the health levels 

of concern. The attached figures present the estimated hazard quotient values (the 

modeled 1-hour concentration of a pollutant divided by its short-term health benchmark) 

at the polar receptors near the facilities. Each set of figures is prefaced with a description 

of the maximum off-site hazard quotient value and where that value occurs. Refer to 

below for a brief summary;

• NEI45571; maximum offsite acute HQ(REL) for hydrofluoric acid of 2; east of 

facility along Pamlico Sound (waterbody)

• NEILA0930004; maximum offsite acute HQ(REL) for hydrofluoric acid of 2, 

southeast of the facility
REL AEGL1 AEGL2 ERPG1 ERPG2

22093NEILA0930005 Elemental Gaseous Mercury 4.2E-01 0.0E+00 1.5E-04 0.0E+00 1.2E-04

12057NEIFL0570008 Hydrofluoric acid 2.9E-01 8.5E-02 3.5E-03 4.4E-02 4.4E-03

12105NEIRFL050059 Hydrofluoric acid 1.6E-01 4.5E-02 1.9E-03 2.3E-02 2.3E-03

28059NEIMS059305 Arsenic compounds 1.2E-01 0.0E+00 0.0E+00 0.0E+00 0.0E+00

16029NEIIDR029000 Hydrofluoric acid 1.1E-01 3.3E-02 1.4E-03 1.7E-02 1.7E-03

12105NEIFL12286 Hydrofluoric acid 7.6E-02 2.2E-02 9.1E-04 1.1E-02 1.1E-03

28059NEIMS059305 Hydrofluoric acid 5.7E-02 1.7E-02 6.8E-04 8.6E-03 8.6E-04

22093NEILA0930005 Arsenic compounds 4.2E-02 0.0E+00 0.0E+00 0.0E+00 0.0E+00

37013NEI45571 Hydrofluoric acid 3.4E-02 9.9E-03 4.1E-04 5.1E-03 5.1E-04

12057NEIFL0570008 Arsenic compounds 2.5E-02 0.0E+00 0.0E+00 0.0E+00 0.0E+00

12057NEIFL0570005 Arsenic compounds 2.3E-02 0.0E+00 0.0E+00 0.0E+00 0.0E+00

12057NEIFL0570005 Hydrofluoric acid 2.2E-02 6.4E-03 2.6E-04 3.3E-03 3.3E-04

12047NEIFLT$4056 Hydrofluoric acid 2.1E-02 6.3E-03 2.6E-04 3.2E-03 3.2E-04

12057NEIFL0570005 Elemental Gaseous Mercury 2.0E-02 0.0E+00 6.9E-06 0.0E+00 5.9E-06

12105NEIRFL050059 Arsenic compounds 1.2E-02 0.0E+00 0.0E+00 0.0E+00 0.0E+00

16077NEI26584 Hydrofluoric acid 1.2E-02 3.5E-03 1.4E-04 1.8E-03 1.8E-04

16077NEI26584 Arsenic compounds 1.1E-02 0.0E+00 0.0E+00 0.0E+00 0.0E+00

12105NEIFL12286 Arsenic compounds 6.5E-03 0.0E+00 0.0E+00 0.0E+00 0.0E+00

12047NEIFLT$4056 Arsenic compounds 5.0E-03 0.0E+00 0.0E+00 0.0E+00 0.0E+00

37013NEI45571 Arsenic compounds 2.8E-03 0.0E+00 0.0E+00 0.0E+00 0.0E+00

37013NEI45571 Elemental Gaseous Mercury 2.5E-03 0.0E+00 8.9E-07 0.0E+00 7.5E-07

56037NEI387 Hydrofluoric acid 2.2E-03 6.5E-04 2.7E-05 3.3E-04 3.3E-05

22093NEILA0930005 Hydrofluoric acid 2.0E-03 5.9E-04 2.4E-05 3.0E-04 3.0E-05

12047NEIFLT$4056 Elemental Gaseous Mercury 1.7E-03 0.0E+00 5.9E-07 0.0E+00 5.0E-07

56037NEI387 Arsenic compounds 1.6E-03 0.0E+00 0.0E+00 0.0E+00 0.0E+00

16077NEI26584 Elemental Gaseous Mercury 1.5E-03 0.0E+00 5.4E-07 0.0E+00 4.6E-07

28059NEIMS059305 Elemental Gaseous Mercury 1.3E-03 0.0E+00 4.7E-07 0.0E+00 4.0E-07

12057NEIFL0570008 Elemental Gaseous Mercury 1.3E-03 0.0E+00 4.5E-07 0.0E+00 3.9E-07

12105NEIRFL050059 Elemental Gaseous Mercury 1.3E-03 0.0E+00 4.4E-07 0.0E+00 3.8E-07

12105NEIFL12286 Elemental Gaseous Mercury 3.3E-04 0.0E+00 1.2E-07 0.0E+00 1.0E-07

16029NEIIDR029000 Arsenic compounds 2.1E-04 0.0E+00 0.0E+00 0.0E+00 0.0E+00

56037NEI387 Elemental Gaseous Mercury 1.4E-04 0.0E+00 4.8E-08 0.0E+00 4.1E-08

16029NEIIDR029000 Elemental Gaseous Mercury 8.8E-05 0.0E+00 3.1E-08 0.0E+00 2.6E-08

12047NEIFLT$4056 Beryllium compounds 0.0E+00 0.0E+00 0.0E+00 0.0E+00 1.3E-04

12057NEIFL0570005 Beryllium compounds 0.0E+00 0.0E+00 0.0E+00 0.0E+00 9.8E-05

Table 1 – Maximum Predicted Acute Risks (HEM-3)

Pollutant

Maximum Hazard Quotient1

Facility NEI ID

Phosphate Fertilizer Production

Screen with Emissions Multiplier 10(x)

 1 of 5
REL AEGL1 AEGL2 ERPG1 ERPG2

Table 1 – Maximum Predicted Acute Risks (HEM-3)

Pollutant

Maximum Hazard Quotient1

Facility NEI ID

Phosphate Fertilizer Production

Screen with Emissions Multiplier 10(x)

12057NEIFL0570008 Beryllium compounds 0.0E+00 0.0E+00 0.0E+00 0.0E+00 9.4E-06

12105NEIFL12286 Beryllium compounds 0.0E+00 0.0E+00 0.0E+00 0.0E+00 2.5E-06

12105NEIRFL050059 Beryllium compounds 0.0E+00 0.0E+00 0.0E+00 0.0E+00 4.4E-06

16029NEIIDR029000 Beryllium compounds 0.0E+00 0.0E+00 0.0E+00 0.0E+00 2.7E-07

16077NEI26584 Beryllium compounds 0.0E+00 0.0E+00 0.0E+00 0.0E+00 9.2E-06

22093NEILA0930005 Beryllium compounds 0.0E+00 0.0E+00 0.0E+00 0.0E+00 4.7E-05

28059NEIMS059305 Beryllium compounds 0.0E+00 0.0E+00 0.0E+00 0.0E+00 3.1E-05

37013NEI45571 Beryllium compounds 0.0E+00 0.0E+00 0.0E+00 0.0E+00 3.5E-06

56037NEI387 Beryllium compounds 0.0E+00 0.0E+00 0.0E+00 0.0E+00 2.7E-06

12047NEIFLT$4056 Gaseous Divalent Mercury 0.0E+00 0.0E+00 0.0E+00 0.0E+00 0.0E+00

12057NEIFL0570005 Gaseous Divalent Mercury 0.0E+00 0.0E+00 0.0E+00 0.0E+00 0.0E+00

12057NEIFL0570008 Gaseous Divalent Mercury 0.0E+00 0.0E+00 0.0E+00 0.0E+00 0.0E+00

12105NEIFL12286 Gaseous Divalent Mercury 0.0E+00 0.0E+00 0.0E+00 0.0E+00 0.0E+00

12105NEIRFL050059 Gaseous Divalent Mercury 0.0E+00 0.0E+00 0.0E+00 0.0E+00 0.0E+00

16029NEIIDR029000 Gaseous Divalent Mercury 0.0E+00 0.0E+00 0.0E+00 0.0E+00 0.0E+00

16077NEI26584 Gaseous Divalent Mercury 0.0E+00 0.0E+00 0.0E+00 0.0E+00 0.0E+00

22093NEILA0930005 Gaseous Divalent Mercury 0.0E+00 0.0E+00 0.0E+00 0.0E+00 0.0E+00

28059NEIMS059305 Gaseous Divalent Mercury 0.0E+00 0.0E+00 0.0E+00 0.0E+00 0.0E+00

37013NEI45571 Gaseous Divalent Mercury 0.0E+00 0.0E+00 0.0E+00 0.0E+00 0.0E+00

56037NEI387 Gaseous Divalent Mercury 0.0E+00 0.0E+00 0.0E+00 0.0E+00 0.0E+00

 Note: BOLD indicates acute risks greater than 1

REL AEGL1 AEGL2 ERPG1 ERPG2

37013NEI45571 Hydrofluoric acid 22.43E+00 7.10E-01 2.91E-02 3.64E-01 3.64E-02

22093NEILA0930004 Hydrofluoric acid 22.20E+00 6.44E-01 2.64E-02 3.30E-01 3.30E-02

12105NEIRFL050059 Hydrofluoric acid 22.20E+00 6.43E-01 2.64E-02 3.29E-01 3.29E-02

16029NEIIDR029000 Hydrofluoric acid 21.75E+00 5.14E-01 2.11E-02 2.63E-01 2.63E-02

12057NEIFL0570008 Hydrofluoric acid 21.42E+00 4.16E-01 1.71E-02 2.13E-01 2.13E-02

12105NEIFL12286 Hydrofluoric acid 21.10E+00 3.21E-01 1.32E-02 1.65E-01 1.65E-02

28059NEIMS059305 Hydrofluoric acid 21.06E+00 3.10E-01 1.27E-02 1.59E-01 1.59E-02

12057NEIFL0570005 Hydrofluoric acid 29.73E-01 2.85E-01 1.17E-02 1.46E-01 1.46E-02

12047NEIFLT$4056 Hydrofluoric acid 26.00E-01 1.76E-01 7.20E-03 9.00E-02 9.00E-03

Phosporic Acid Manufacturing

Facility NEI ID Pollutant

Maximum Hazard Quotient1

1 Some maximum acute impacts may be at onsite locations.

 2 of 5
REL AEGL1 AEGL2 ERPG1 ERPG2

Table 1 – Maximum Predicted Acute Risks (HEM-3)

Pollutant

Maximum Hazard Quotient1

Facility NEI ID

Phosphate Fertilizer Production

Screen with Emissions Multiplier 10(x)

37013NEI45571 Elemental Gaseous Mercury 4.43E-01 0.00E+00 1.56E-04 0.00E+00 1.33E-04

22005NEI6147 Hydrofluoric acid 24.03E-01 1.18E-01 4.84E-03 6.05E-02 6.05E-03

12047NEIFLT$4056 Arsenic compounds 2.09E-01 0.00E+00 0.00E+00 0.00E+00 0.00E+00

12105NEIFL12286 Arsenic compounds 1.92E-01 0.00E+00 0.00E+00 0.00E+00 0.00E+00

16077NEI26584 Hydrofluoric acid 2, 3 1.84E-01 5.37E-02 2.20E-03 2.75E-02 2.75E-03

56037NEI387 Hydrofluoric acid 27.28E-02 2.13E-02 8.74E-04 1.09E-02 1.09E-03

28059NEIMS059305 Arsenic compounds 6.65E-02 0.00E+00 0.00E+00 0.00E+00 0.00E+00

12105NEIRFL050059 Arsenic compounds 4.86E-02 0.00E+00 0.00E+00 0.00E+00 0.00E+00

37013NEI45571 Hydrochloric acid 1.94E-02 1.51E-02 1.23E-03 9.05E-03 1.36E-03

12057NEIFL0570008 Arsenic compounds 8.92E-03 0.00E+00 0.00E+00 0.00E+00 0.00E+00

37013NEI45571 Arsenic compounds 7.58E-03 0.00E+00 0.00E+00 0.00E+00 0.00E+00

16077NEI26584 Arsenic compounds 7.58E-03 0.00E+00 0.00E+00 0.00E+00 0.00E+00

12057NEIFL0570005 Arsenic compounds 6.99E-03 0.00E+00 0.00E+00 0.00E+00 0.00E+00

12047NEIFLT$4056 Elemental Gaseous Mercury 6.08E-03 0.00E+00 2.15E-06 0.00E+00 1.82E-06

37013NEI45571 Acrolein 3.93E-03 1.43E-04 4.28E-05 8.94E-05 2.89E-05

16029NEIIDR029000 Arsenic compounds 3.93E-03 0.00E+00 0.00E+00 0.00E+00 0.00E+00

16077NEI26584 Elemental Gaseous Mercury 2.58E-03 0.00E+00 9.10E-07 0.00E+00 7.74E-07

12057NEIFL0570005 Elemental Gaseous Mercury 2.02E-03 0.00E+00 7.14E-07 0.00E+00 6.07E-07

12105NEIFL12286 Elemental Gaseous Mercury 1.95E-03 0.00E+00 6.88E-07 0.00E+00 5.85E-07

56037NEI387 Arsenic compounds 1.88E-03 0.00E+00 0.00E+00 0.00E+00 0.00E+00

22093NEILA0930004 Arsenic compounds 1.80E-03 0.00E+00 0.00E+00 0.00E+00 0.00E+00

22005NEI6147 Arsenic compounds 1.20E-03 0.00E+00 0.00E+00 0.00E+00 0.00E+00

12105NEIRFL050059 Elemental Gaseous Mercury 1.05E-03 0.00E+00 3.71E-07 0.00E+00 3.16E-07

28059NEIMS059305 Elemental Gaseous Mercury 1.02E-03 0.00E+00 3.60E-07 0.00E+00 3.06E-07

37013NEI45571 Formaldehyde 9.99E-04 5.00E-05 3.23E-06 4.58E-05 4.58E-06

22093NEILA0930004 Elemental Gaseous Mercury 4.28E-04 0.00E+00 1.51E-07 0.00E+00 1.28E-07

12057NEIFL0570008 Elemental Gaseous Mercury 3.97E-04 0.00E+00 1.40E-07 0.00E+00 1.19E-07

16029NEIIDR029000 Elemental Gaseous Mercury 2.73E-04 0.00E+00 9.64E-08 0.00E+00 8.19E-08

22005NEI6147 Elemental Gaseous Mercury 1.28E-04 0.00E+00 4.52E-08 0.00E+00 3.84E-08

37013NEI45571 Benzyl chloride 9.90E-05 0.00E+00 0.00E+00 4.57E-06 4.57E-07

56037NEI387 Elemental Gaseous Mercury 9.81E-05 0.00E+00 3.46E-08 0.00E+00 2.94E-08

37013NEI45571 Acetaldehyde 4.12E-05 2.39E-07 3.95E-08 1.07E-06 5.37E-08

37013NEI45571 Benzene 3.41E-05 2.61E-07 1.71E-08 2.77E-07 9.24E-08

37013NEI45571 Chloroform 1.34E-05 0.00E+00 6.46E-09 0.00E+00 8.35E-09

37013NEI45571 Methyl bromide 1.39E-06 0.00E+00 6.63E-09 0.00E+00 2.86E-08

37013NEI45571 Carbon disulfide 7.13E-07 1.11E-07 8.84E-09 1.43E-06 2.76E-08

37013NEI45571 Methylene chloride 7.03E-07 1.43E-08 5.18E-09 9.84E-09 3.78E-09

 3 of 5
REL AEGL1 AEGL2 ERPG1 ERPG2

Table 1 – Maximum Predicted Acute Risks (HEM-3)

Pollutant

Maximum Hazard Quotient1

Facility NEI ID

Phosphate Fertilizer Production

Screen with Emissions Multiplier 10(x)

37013NEI45571 Toluene 4.58E-07 2.26E-08 3.77E-09 8.92E-08 1.54E-08

37013NEI45571 Phenol 9.37E-08 9.37E-09 6.11E-09 1.43E-08 2.86E-09

37013NEI45571 Xylenes (mixed) 5.71E-08 2.25E-09 3.14E-10 0.00E+00 0.00E+00

37013NEI45571 Tetrachloroethene 5.06E-08 4.21E-09 6.32E-10 1.49E-09 7.22E-10

37013NEI45571 Styrene 4.04E-08 9.98E-09 1.54E-09 4.04E-09 7.71E-10

37013NEI45571 o-Xylene 7.03E-09 0.00E+00 0.00E+00 0.00E+00 0.00E+00

12047NEIFLT$4056 Beryllium compounds 0.00E+00 0.00E+00 0.00E+00 0.00E+00 4.42E-05

12057NEIFL0570005 Beryllium compounds 0.00E+00 0.00E+00 0.00E+00 0.00E+00 1.87E-05

12057NEIFL0570008 Beryllium compounds 0.00E+00 0.00E+00 0.00E+00 0.00E+00 1.88E-06

12105NEIFL12286 Beryllium compounds 0.00E+00 0.00E+00 0.00E+00 0.00E+00 2.02E-05

12105NEIRFL050059 Beryllium compounds 0.00E+00 0.00E+00 0.00E+00 0.00E+00 6.83E-06

16029NEIIDR029000 Beryllium compounds 0.00E+00 0.00E+00 0.00E+00 0.00E+00 1.79E-06

16077NEI26584 Beryllium compounds 0.00E+00 0.00E+00 0.00E+00 0.00E+00 9.56E-06

22005NEI6147 Beryllium compounds 0.00E+00 0.00E+00 0.00E+00 0.00E+00 4.88E-07

22093NEILA0930004 Beryllium compounds 0.00E+00 0.00E+00 0.00E+00 0.00E+00 2.59E-06

28059NEIMS059305 Beryllium compounds 0.00E+00 0.00E+00 0.00E+00 0.00E+00 2.73E-06

37013NEI45571 Beryllium compounds 0.00E+00 0.00E+00 0.00E+00 0.00E+00 8.21E-06

56037NEI387 Beryllium compounds 0.00E+00 0.00E+00 0.00E+00 0.00E+00 3.21E-06

37013NEI45571 Chlorobenzene 0.00E+00 1.62E-08 1.08E-09 0.00E+00 0.00E+00

37013NEI45571 Cumene 0.00E+00 7.20E-10 1.20E-10 0.00E+00 0.00E+00

37013NEI45571 Dimethyl sulfate 0.00E+00 1.36E-05 2.63E-06 0.00E+00 0.00E+00

37013NEI45571 Ethyl benzene 0.00E+00 2.34E-08 6.84E-10 0.00E+00 0.00E+00

37013NEI45571 Ethylene dibromide 0.00E+00 3.13E-10 2.26E-10 0.00E+00 0.00E+00

37013NEI45571 Ethylene dichloride 0.00E+00 0.00E+00 0.00E+00 6.78E-09 1.67E-09

37013NEI45571 Methyl chloride 0.00E+00 0.00E+00 9.47E-09 0.00E+00 2.17E-08

37013NEI45571 Methyl hydrazine 0.00E+00 0.00E+00 1.80E-06 0.00E+00 0.00E+00

37013NEI45571 Methyl methacrylate 0.00E+00 9.72E-09 1.39E-09 0.00E+00 0.00E+00

37013NEI45571 Methyl tert-butyl ether 0.00E+00 6.60E-09 5.66E-10 0.00E+00 0.00E+00

37013NEI45571 n-Hexane 0.00E+00 0.00E+00 1.89E-10 0.00E+00 0.00E+00

37013NEI45571 Propionaldehyde 0.00E+00 1.17E-07 2.08E-08 0.00E+00 0.00E+00

37013NEI45571 Vinyl acetate 0.00E+00 1.07E-08 4.09E-10 1.43E-08 9.92E-10

 Note: BOLD indicates acute risks greater than 1

2 An acute hourly multiplier of 1 was used vs 10

1 Some maximum acute impacts may be at onsite locations.

 4 of 5
REL AEGL1 AEGL2 ERPG1 ERPG2

Table 1 – Maximum Predicted Acute Risks (HEM-3)

Pollutant

Maximum Hazard Quotient1

Facility NEI ID

Phosphate Fertilizer Production

Screen with Emissions Multiplier 10(x)

3 An acute hourly multiplier of 2 was used for hydrofluoric acid emissions vs 10 based upon site specific data, refer to 

memorandum entitled, “Emissions Data Used in Residual Risk Modeling: Phosphoric Acid and Phosphate Fertilizer 

Production Source Categories” available in the docket for this action. 

 5 of 5
37013NEI45571 Hydrofluoric acid REL 2.4 1.6 Max off-site HQ with emission specific multipliers

22093NEILA0930004 Hydrofluoric acid REL 2.2 2.2 Max off-site HQ with emission specific multipliers

12105NEIRFL050059 Hydrofluoric acid REL 2.2 0.6 Max off-site HQ with emission specific multipliers

16029NEIIDR029000 Hydrofluoric acid REL 1.8 0.6 Max off-site HQ with emission specific multipliers

Phosphoric Acid Manufacturing

1

 Indicates modeling technique used to refined estimates

Table 2: Maximum Predicted Acute Risks Greater than 1 (Refined Approach)

Facility NEI ID Pollutant Criteria

HEM-3

(Screening)

Refined

Results Refined Modeling Approach 1
Phosphoric Acid Manufacturing 

(Refined Acute Risk Assessment)

• Figure 1 – NEI4571; maximum offsite acute 

HQ(REL) for hydrofluoric acid of 2; east of facility

• Figure 2 – NEILA0930004 maximum offsite acute 

HQ(REL) for hydrofluoric acid of 2; southeast of 

facility
Figure 1 – NEI45571 Acute Hydrofluoric Acid HQ (REL)
Figure 2 – NEILA0930004 Acute Hydrofluoric Acid HQ (REL)