-

UNITED STATES ENVIRONMENTAL PROTECTION

AGENCY

WASHINGTON D.C.. 20460

July 6, 2010

PC Code: 043301

DP Barcode: 379499

MEMORANDUM

Subject:

To:

And:

Verification of Furfural Air Estimated Exposure Concentrations

Kelly Orourke, Biologist

Ray Kent, Branch Chief

Health Effects Division (7509P)

Office of Pesticide Programs

Cynthia Giles-Parker, Branch Chief

Mary Waller, Review Manager

Tamue Gibson, Risk Manager Reviewer

Fungicide Branch

Registration Division (7505P)

Office of Pesticide Programs

From:

Through:

Gabe Rothman, Environmental Scientist

Environmental Risk Branch 5

Environmental Fate and Effects Division (7507P)

Office of Pesticide Programs

Mah Shamim, Chief, Environmental Risk Branch 5

Environmental Fate and Effects Division

Office of Pesticide Programs

The Environmental Fate and Effects Division (EFED) has verified the Industrial Source

Complex Short Tenn Model (ISCST3 version 02035, developed by the EPA Office of

Air Quality Planning and Standards) maximum peak estimated exposure concentrations

in the air submitted by the registrant in its justification to reduce the re-entry time interval

restriction for gold course workers after furfural treatments. In general, EFED agrees that

the modeling method that was utilized by the registrant is suitable for this purpose and

results are conservative for the scenarios presented.

1
2

The ISCST3 modeling work (e.g., input files, output files, and meteorological files) was 

provided by Sullivan Environmental Consulting, Inc. Consistent with OPPTS air 

dispersion modeling techniques using the Probablistic Exposure and Risk Model for 

Fumigants (PERFUM), which processes ISCST3 output, ISCST3 was run over five years 

of meteorological data. The meteorological station chosen by the registrant was from 

Tallahassee, FL and which encompassed data between the years 2001 – 2006. ISCST3 

estimated air exposure concentrations were output over a locus of points focused over 

many rings radially extending out from the treated field of sizes 0.16 acres and 0.5 acres 

which the registrant believes to be representative of golf course tee and green areas. The 

registrant executed modeling for each flux rate in the temporal flux profile that was 

measured at the Georgia furfural third treatment to turf plot field volatility study (MRID 

No. 47569101) which were equivalent with EFED’s calculated flux rates. Estimated 

exposure concentrations were determined for each flux rate held at steady state over the 

five years. This provides a suitable statistical sample of each flux rate over different 

meteorological conditions and its influence on air concentrations. For each flux rate, the 

maximum peak concentration was reported by the registrant and is shown in Tables 2 and 

3 in the letter entitled, “Comments to Docket No. EPA-HQ-OPP-2009-0722: 

Registrant’s Response to the Agency’s Recommendation for the Establishment of 

Restricted Entry Intervals for Golf Course Uses of Multiguard® Protect”, submitted by 

Toxcel on behalf of the registrant. The modeling results provided by the registrant are 

conservative as compared to the PERFUM modeling technique for the following reasons: 

• The registrant reported maximum peak estimated exposure air concentration 

values rather than concentrations at a specific significance level such as is often 

chosen by OPPTS for the basis of regulatory decisions. 

• The time of day effect on flux rates is not taken into account in the registrant’s 

modeling. One flux rate at a time is considered and subject to five years of 

meteorological data rather than the varying flux rates over time which are subject 

to the five years of meteorology as processed in PERFUM used for OPPTS risk 

assessments. 

• The registrant reported estimated exposure air concentration values at ground 

level rather than breathing height which is at approximately 1.5 meters above 

ground level. Estimated exposure air concentrations in PERFUM are reported at 

1.5 meters above ground level. Given that furfural is being emitted as a ground 

release from a treated field, maximum peak air concentrations are expected to be 

highest closer to the ground. 

EFED performed a verification of the registrant’s modeling using the SCREEN3 air 

dispersion model (version 96043, also developed at the EPA Office of Air Quality 

Planning and Standards). As is the case in PERFUM, the SCREEN3 models plume 

dispersion dynamics equivalent to ISCST3. However, rather than using a robust 

multiple-year meteorological dataset, SCREEN3 uses a combination of 54 wind speeds 

and turbulence stability classes and conservatively identifies the worst-case case 

combination of meteorological data coupled with the assumption that the wind is blowing 
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directly from the pollution source towards the receiving point of interest in order to 

obtain the peak concentrations. Given the registrant’s presentation of maximum peak 

estimated exposure concentrations at points focused at rings around a treated field, the 

SCREEN3 results should be similar or equivalent to the registrant’s values. EFED 

modeling using the flux rates and conducted at ground-level consistent with the registrant 

(not shown) resulted in slightly higher values than the registrant estimated air exposure 

values. 

As per the Health Effects Division’s request, EFED also conducted modeling using 

SCREEN3 independent of the registrant’s modeling to adjust flux rates to reflect the 

maximum labeled application rate and to account for the appropriate breathing height of 

1.5 meters above ground level. In addition, EFED accounted for field sizes up to 1 acre. 

Hence, SCREEN3 modeling was conducted for 0.16 acres, 0.5 acres, and 1.0 acre treated 

fields. Table 1 below shows the input values for the SCREEN3 parameters. 

Table 1. Input parameters into SCREEN3. 

Input Parameter Option/Value 

Source Type Area 

Emission Rates (g/m2s) Georgia Study Hours 0 - 1 1,3 – 382.32 x 10-6 

Georgia Study Hours 1 - 2 1,3– 0.06 x 10-6 

California Study Hours 0 - 1 2,3– 1,064.74 x 10-6 

California Study Hours 1 - 2 2,3– 131.1 x 10-6

California Study Hours 2 - 3 2,3– 0.32 x 10-6

Source Height (m) 0 

Length of Large Sides of 

Source (m) 

25.45, 44.00, 63.60 

Length of Smaller Sides of 

Source (m) 

25.45, 44.00, 63.60 

Receptor Height (m) 1.5 

Urban/Rural Option Rural 

1. Flux profile extracted based on the third treatment to turf subplot (MRID No. 47569101). 

2. Flux profile extracted based on the second treatment to turf subplot (MRID No. 47483901). 

3. Flux values scaled from measured values at application rates from field volatility studies to 69.4 lbs. a.i./acre.1. 

Table 2 below shows the SCREEN3 maximum peak estimated exposure concentrations 

(EECs) in air possible over time after furfural applications. In general, maximum peak 

EECs fall to small values for all field sizes after the first hour following the application 

based on flux rates developed from the Georgia study. The results using flux rates 

developed from the California second treatment to turf plot field volatility study (MRID 

No. 47483901), where higher flux rates were measured than the Georgia third treatment 

to turf plot field volatility study (MRID No. 47569101), suggests a similar trend after the 

second hour following the application. EFED notes that maximum peak EECs over later 

time periods following the application than what is shown here will be even smaller as 

flux rates measured in all of the turf plots decrease to even lower levels over time. 
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Table 2. SCREEN3 maximum peak estimated exposure 

concentrations in air at times after application.

Study Basis/Modeled 

Field Size 

Hours PostApplication Flux Rate 

(μg/m2

s) 

Maximum 

Peak EEC in 

Air 

(μg/m3) 

Georgia – 0.16 Acres 0 - 1 382.32 1,3 3,884.37 

Georgia – 0.16 Acres 1 - 2 0.06 1,3 0.61 

Georgia – 0.5 Acres 0 - 1 382.32 1,3 6,801.47 

Georgia – 0.5 Acres 1 - 2 0.06 1,3 1.07 

Georgia – 1.0 Acre 0 - 1 382.32 1,3 9,584.76 

Georgia – 1.0 Acre 1 - 2 0.06 1,3 1.50 

California – 0.16 Acres 0 - 1 1,064.74 2,3 10,817.76 

California – 0.16Acres 1 - 2 131.1 2,3 1,331.98 

California – 0.16 Acres 2 - 3 0.32 2,3 3.25 

California – 0.5 Acres 0 - 1 1,064.74 2,3 18,941.72 

California – 0.5 Acres 1 - 2 131.1 2,3 2,332.27 

California – 0.5 Acres 2 - 3 0.32 2,3 5.69 

California – 1.0 Acre 0 - 1 1,064.74 2,3 26,693.03 

California – 1.0 Acre 1 - 2 131.1 2,3 3,286.68 

California – 1.0 Acre 2 - 3 0.32 2,3 8.02 

1. Flux profile extracted based on the third treatment to turf suplot (MRID No. 47569101). 

2. Flux profile extracted based on the second treatment to turf subplot (MRID No. 47483901). 

3. Flux values scaled from measured values at application rates from field volatility studies to 69.4 lbs. a.i./acre. 
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Attachment 1 – SCREEN3 Modeling Output Files 
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Figure 1-1. SCREEN3 modeling run normalized to 1 g/m2s flux rate for 

0.16 acre field. 

 

07/01/10 

11:54:44 

 *** SCREEN3 MODEL RUN *** 

 *** VERSION DATED 96043 *** 

 Furfural REI 

 SIMPLE TERRAIN INPUTS: 

 SOURCE TYPE = AREA 

 EMISSION RATE (G/(S-M**2)) = 1.00000 

 SOURCE HEIGHT (M) = .0000 

 LENGTH OF LARGER SIDE (M) = 25.4500 

 LENGTH OF SMALLER SIDE (M) = 25.4500 

 RECEPTOR HEIGHT (M) = 1.5000 

 URBAN/RURAL OPTION = RURAL 

 THE REGULATORY (DEFAULT) MIXING HEIGHT OPTION WAS SELECTED. 

 THE REGULATORY (DEFAULT) ANEMOMETER HEIGHT OF 10.0 METERS WAS ENTERED. 

 MODEL ESTIMATES DIRECTION TO MAX CONCENTRATION 

 BUOY. FLUX = .000 M**4/S**3; MOM. FLUX = .000 M**4/S**2. 

 *** FULL METEOROLOGY *** 

 ********************************** 

 *** SCREEN AUTOMATED DISTANCES *** 

 ********************************** 

 *** TERRAIN HEIGHT OF 0. M ABOVE STACK BASE USED FOR FOLLOWING 

DISTANCES *** 

 DIST CONC U10M USTK MIX HT PLUME MAX DIR 

 (M) (UG/M**3) STAB (M/S) (M/S) (M) HT (M) (DEG) 

 ------- ---------- ---- ----- ----- ------ ------ ------- 

 1. .8613E+06 5 1.0 1.0 10000.0 .00 43. 

 100. .8246E+07 6 1.0 1.0 10000.0 .00 45. 

 MAXIMUM 1-HR CONCENTRATION AT OR BEYOND 1. M: 

 58. .1016E+08 6 1.0 1.0 10000.0 .00 45. 

 *************************************** 

 *** SUMMARY OF SCREEN MODEL RESULTS *** 

 *************************************** 

 CALCULATION MAX CONC DIST TO TERRAIN 

 PROCEDURE (UG/M**3) MAX (M) HT (M) 

 -------------- ----------- ------- ------- 

 SIMPLE TERRAIN .1016E+08 58. 0. 

 *************************************************** 
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Figure 1-2. SCREEN3 modeling run normalized to 1 g/m2s flux rate for 

0.5 acre field. 

 

07/01/10 

12:09:40 

 *** SCREEN3 MODEL RUN *** 

 *** VERSION DATED 96043 *** 

 Furfural REI 

 SIMPLE TERRAIN INPUTS: 

 SOURCE TYPE = AREA 

 EMISSION RATE (G/(S-M**2)) = 1.00000 

 SOURCE HEIGHT (M) = .0000 

 LENGTH OF LARGER SIDE (M) = 44.0000 

 LENGTH OF SMALLER SIDE (M) = 44.0000 

 RECEPTOR HEIGHT (M) = 1.5000 

 URBAN/RURAL OPTION = RURAL 

 THE REGULATORY (DEFAULT) MIXING HEIGHT OPTION WAS SELECTED. 

 THE REGULATORY (DEFAULT) ANEMOMETER HEIGHT OF 10.0 METERS WAS ENTERED. 

 MODEL ESTIMATES DIRECTION TO MAX CONCENTRATION 

 BUOY. FLUX = .000 M**4/S**3; MOM. FLUX = .000 M**4/S**2. 

 *** FULL METEOROLOGY *** 

 ********************************** 

 *** SCREEN AUTOMATED DISTANCES *** 

 ********************************** 

 *** TERRAIN HEIGHT OF 0. M ABOVE STACK BASE USED FOR FOLLOWING 

DISTANCES *** 

 DIST CONC U10M USTK MIX HT PLUME MAX DIR 

 (M) (UG/M**3) STAB (M/S) (M/S) (M) HT (M) (DEG) 

 ------- ---------- ---- ----- ----- ------ ------ ------- 

 1. .4288E+07 5 1.0 1.0 10000.0 .00 45. 

 100. .1562E+08 6 1.0 1.0 10000.0 .00 45. 

 MAXIMUM 1-HR CONCENTRATION AT OR BEYOND 1. M: 

 67. .1779E+08 6 1.0 1.0 10000.0 .00 45. 

 *************************************** 

 *** SUMMARY OF SCREEN MODEL RESULTS *** 

 *************************************** 

 CALCULATION MAX CONC DIST TO TERRAIN 

 PROCEDURE (UG/M**3) MAX (M) HT (M) 

 -------------- ----------- ------- ------- 

 SIMPLE TERRAIN .1779E+08 67. 0. 
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Figure 1-3. SCREEN3 modeling run normalized to 1 g/m2s flux rate for 

1.0 acre field. 

 

07/01/10 

12:18:08 

 *** SCREEN3 MODEL RUN *** 

 *** VERSION DATED 96043 *** 

 Furfural REI 

 SIMPLE TERRAIN INPUTS: 

 SOURCE TYPE = AREA 

 EMISSION RATE (G/(S-M**2)) = 1.00000 

 SOURCE HEIGHT (M) = .0000 

 LENGTH OF LARGER SIDE (M) = 63.6000 

 LENGTH OF SMALLER SIDE (M) = 63.6000 

 RECEPTOR HEIGHT (M) = 1.5000 

 URBAN/RURAL OPTION = RURAL 

 THE REGULATORY (DEFAULT) MIXING HEIGHT OPTION WAS SELECTED. 

 THE REGULATORY (DEFAULT) ANEMOMETER HEIGHT OF 10.0 METERS WAS ENTERED. 

 MODEL ESTIMATES DIRECTION TO MAX CONCENTRATION 

 BUOY. FLUX = .000 M**4/S**3; MOM. FLUX = .000 M**4/S**2. 

 *** FULL METEOROLOGY *** 

 ********************************** 

 *** SCREEN AUTOMATED DISTANCES *** 

 ********************************** 

 *** TERRAIN HEIGHT OF 0. M ABOVE STACK BASE USED FOR FOLLOWING 

DISTANCES *** 

 DIST CONC U10M USTK MIX HT PLUME MAX DIR 

 (M) (UG/M**3) STAB (M/S) (M/S) (M) HT (M) (DEG) 

 ------- ---------- ---- ----- ----- ------ ------ ------- 

 1. .8519E+07 5 1.0 1.0 10000.0 .00 45. 

 100. .2341E+08 6 1.0 1.0 10000.0 .00 45. 

 MAXIMUM 1-HR CONCENTRATION AT OR BEYOND 1. M: 

 77. .2507E+08 6 1.0 1.0 10000.0 .00 45. 

 *************************************** 

 *** SUMMARY OF SCREEN MODEL RESULTS *** 

 *************************************** 

 CALCULATION MAX CONC DIST TO TERRAIN 

 PROCEDURE (UG/M**3) MAX (M) HT (M) 

 -------------- ----------- ------- ------- 

 SIMPLE TERRAIN .2507E+08 77. 0. 

 ***************************************************