SUPPLEMENTAL MATERIALS
Above-Ground vs. Below-Ground Structural Applications
The approved uses of certain bifenthrin, cypermethrin, fenvalerate, and permethrin products
include treatment of subterranean termites. The fenvalerate product was labeled for subterranean
termite control only, so entries for this product were removed entirely. Label guidelines were
largely identical, with the exception of emulsion strength. Labels provided guidelines for the
treatment of subterranean termites in both pre-construction and post-construction circumstances.
Pre-construction guidelines specified a dosage rate of 1 gallon of emulsion (appropriately diluted
product to a final w/w active ingredient percentage) per 10 square feet of horizontal surface, and
4 gallons of emulsion per 10 linear feet of vertical surface (e.g., foundation walls). Typical preconstruction application would occur immediately prior to pouring the building slab or
foundation. Once covered, the application is assumed to no longer pose a significant hazard to
surface water quality.
Guidelines for post-construction subterranean termite treatment includes trenching, rodding, or
sub-slab injection through drilled holes. The recommended dosage rate is similar to the preconstruction vertical treatment of 4 gallons per 10 linear feet. Post-construction termite
treatments often target a small infestation along a short distance of wall. The exact nature of
post-construction termite treatment is ill defined, so no attempt was made to screen the PUR
database of these below-ground treatments. However, pre-construction whole house termite
treatments availed themselves to estimation and screening.
The below-ground, pre-construction termite screening procedure first involved estimating the
typical size of a single family residential home - for the Sacramento metropolitan area, the
median square footage of a single family home was estimated to be 1,437 ft2
(http://www.movoto.com; November 11, 2011) To obtain an estimate of the perimeter, a home
was assumed to be single story and square, yielding a perimeter of 151.6 feet. Based on the label
dosage rates previously described, a home of this area and dimension would require 204.3
gallons of diluted product. Product labels specify a bifenthrin emulsion of 0.06%, a
cypermethrin emulsion of 0.25%, and a permethrin emulsion of 0.5%. Assuming a specific
gravity of 1.0 for the final mixed product, a single pre-construction termite treatment of a median
sized Sacramento home would yield an application of 1.0 pound of bifenthrin, 4.2 pounds of
cypermethrin, or 8.5 pounds of permethrin.
These pyrethroid specific application amounts were taken as reasonable thresholds for screening
the PUR database. The PUR database includes a field for “application count”, representing the
number of discrete applications included within a particular entry in a given month. Dividing the
total applied chemical mass by its application count yielded an estimate of the average amount of
pyrethroid applied for a single treatment in a given month. This estimated treatment amount was
then compared to the previously determined screening thresholds. Unfortunately, however, the
“application count” field was inconsistently filled out for most years. Only for the calendar years
1995, 1996, 1997, 2009, and 2010 was the “application count” field completed for each entry.
This required formulating a screening threshold that could be applied consistently to the “total
chemical applied” field which was populated for all of the years to be modeled. This screening
threshold was acquired by a process of comparing threshold value Type I and Type II errors,
where the treatment amounts calculated for those entries with application count information were
assumed as the true indicator of a below grade application. An appropriate screening value was
taken as the value that produced approximately equal Type I and Type II errors (Table S1). Final
screening values applied to all years of the database were 21 pounds for bifenthrin, 17 pounds for
cypermethrin, and 35 pounds for permethrin. For these pyrethroids, entries in the database that
corresponded to products labeled for subterranean termite control with total applied chemical
amounts in excess of these screening values were removed.
Computation Process
Figure S1 presents the computation process utilized by the model to arrive at daily predictions of
river bifenthrin concentration. The depicted process was identical for all pyrethroid active
ingredients.
TABLE S1. Pesticide Use Reporting (PUR)
database chemical identification numbers
Chemical Name
Chemical ID
Fenvalerate
1963
Permethrin
2008
Cypermethrin
2171
Cyfluthrin
2223
Lambda Cyhalothrin
2297
Bifenthrin
2300
Esfenvalerate
2321
Deltamethrin
3010
Beta-Cyfluthrin
3956
Fenvalerate, Other
91963
Related
Permethrin, Other
92008
Related
Deltamethrin, Other
93010
Related
TABLE S2. Categories of formulation of xxx and the
formulations included in xxx.
Formulation Type
Specific Formulations Included
Emulsifiable
Emulsifiable concentrates
Concentrate
Suspension concentrate, wettable
Suspension
powder, microencapsulated, flowable
Concentrate
concentrate
Granular
Other
Granules, flakes, dusts, powder
Aerosols, foggers, baits, gels, foams
TABLE S3. Regulator amendments to perimeter band treatment of structures
Previous Regulation
New Regulation
Pervious Surfaces (vertical surface in contact with pervious horizontal surface)
Permissible application of 6 o 10 feet on
Permissible application of 3 feet on
the horizontal and 2 to 3 feet on the vertical
horizontal and 2 feet on vertical
Impervious Surfaces (vertical surface in contact with impervious horizontal surface)
Permissible application of 2 feet on
Permissible application of 6 o 10 feet on
vertical; on horizontal surfaces only spot,
the horizontal and 2 to 3 feet on the vertical
crack and crevice, and pin stream
application permitted
Additional Rules for Bifenthrin (in addition to those above)
No application to a vertical surface in
direct contact with an impervious
Permissible application of 6 o 10 feet on
horizontal surface and no spot, crack and
the horizontal and 2 to 3 feet on the vertical
crevice, or pin stream application to any
unprotected horizontal impervious surface.
TABLE S4. Estimated errors related to below-ground screening
procedure
Type I Error
Type II Error
Total Error
Bifenthrin
Test
Pounds
%
Pounds
%
Pounds
%
15 lbs
877.7
9.7
515.3
5.7
1,393.0
15.4
20 lbs
671.2
7.4
581.7
6.4
1,252.9
13.8
21 lbs
650.9
7.2
581.7
6.4
1,232.6
13.6
25 lbs
650.8
7.2
628.5
6.9
1,279.3
14.1
30 lbs
596.9
6.6
741.1
8.2
1,337.9
14.8
Type I Error
Type II Error
Total Error
Cypermethrin
Test
Pounds
%
Pounds
%
Pounds
%
10 lbs
2,936.9
33.6
1,142.6
13.1
4,079.5
46.6
15 lbs
2,359.4
27.0
2,214.9
25.3
4,574.3
52.3
17 lbs
2,311.0
26.4
2,441.8
27.9
4,752.9
54.3
20 lbs
2,184.6
25.0
2,806.9
32.1
4,991.6
57.0
25 lbs
1,960.6
22.4
3,456.1
39.5
5,416.7
61.9
Type I Error
Type II Error
Total Error
Permethrin
Test
Pounds
%
Pounds
%
Pounds
%
30 lbs
2,849.6
10.4
1,942.0
7.1
4,791.6
17.6
35 lbs
2,627.1
9.6
2,714.0
9.9
5,341.1
19.6
40 lbs
2,475.1
9.1
3,124.8
11.4
5,570.0
20.5
50 lbs
1,637.2
6.0
4,288.1
15.7
5,925.3
21.7
Note: Shaded area represents selected screening value
Ho: Application entry should remain
Ha: Application entry should be removed
Test: Rate of error associated with application amount screening
threshold (in pounds)
Type I Error (False Positive): Reject a true null hypothesis; omit
application entry when, in fact, the entry should remain
Type II Error (False Negative): Fail to reject a false null hypothesis;
preserve an application entry when, in fact, it should be omitted.
Calculate Pyrethroid Application Rate for Day Xi
Pesticide Use Input File
(monthly application
masses)
MONBFi (kg)
DBFi = MONBFi/MON_DAY
No (WBFi = 0)
Precipitation
on Day Xi?
Yes
Precipitation Input File
(daily precipitation
depth)
PPT (ml)
Calculate Precipitation Runoff Volume for Day Xi(ml)
PPTM3S = PPT*AREA*RV
Calculate Pyrethroid Washoff for Day Xi (kg)
Pesticide Washoff
Parameter Input
(B0i, B2i, Kdegi) (kg)
Flow Input File
(daily river flow)
FLOW (L/d)
Wi = B0i + B2i* PPT
WBFi = Wi*REBFi
TBF = WBFi
Calculate Pyrethroid River Concentration for Day
Xi (ng/L)
RVBF = TBF/(FLOW+PPTM3S)
Calculate Pyrethroid Mass Remaining at End of Day Xi
REBFi = RE2BFi*EXP(-Kdegi)+DBFi-WBFi(kg)
Repeat for Next Day
DBFi
MONBFi
MON_Day
PPTM3S
PPT
AREA
RV
Wi
B0i
B2i
WBFi
REBFi
RE2BFi
TBF
FLOW
RVBF
Daily bifenthrin application for formulation:surface combination
Monthly bifenthrin application for formulation:surface combination
Days in given month
Daily precipitation runoff volume
Daily precipitation depth
Area of watershed
Runoff coefficient averaged for land use
Washoff coefficient for formulation:surface combination
Washoff model intercept for formulation:surface combination
Washoff model slope for formulation:surface combination
Washoff mass of bifenthrin for formulation:surface combination
Bifenthrin remaining by formulation:surface combination
Previous day bifenthrin remaining by formulation:surface combination
Total daily bifenthrin massed washed off
Daily river flow volume
Daily bifenthrin river concentration
Kdegi
Set time decay coefficient for formulation surface combination
Save RVBF to
Output File; Scale by Attenuation
Factor; Convert to TU
Cumulative Washoff (Mw/Mavail)
Figure S1. Computation process utilized in river concentration predictions.
0.020
0.015
0.010
0.005
0.000
0
10
20
30
Precipitation Depth (mm)
1.5 Hour
1 Day
7 days
21 Days
49 Days
FIGURE S2. Linear fits of an emulsifiable concentrate of esfenvalerate applied on concrete
over a gradient of set-time. Data is for cumulative washoff of esfenvalerate from a single
concrete surface treated on a single occasion at time zero.