H.  Wettable Powder Used for Spraying

Investigators evaluated only bendiocarb, 76% solid, wettable powder (WP).

1.  Application Scenarios

Six percent of the PM exposure interviews cited use of Bendiocarb WP (Table 13), which was used to control pests such as cockroaches, fleas, mosquitoes, ticks, and venomous arthropods. It was applied mainly by low-pressure 2-gallon handwand sprayers. Application appears to have been evenly split between outdoors and indoors. Outdoor applications were broadcast treatments typically made to the near-ground portions of buildings and tents, and other places where the target pests congregated. Indoor applications probably included crack and crevice treatment, as well as broadcast treatment of floors. During crack and crevice application, a stream or cone of spray is directed at cracks and crevices, such as commonly occur where a wall meets a floor. Investigators assumed surfaces adjacent to the cracks were treated, and that overspray could have been substantial. Additionally, building size, condition, and configuration impacted the relative fraction of surface area treated. Investigators assumed a much greater fraction of surface area was treated in a small latrine as opposed to a large rectangular mess hall. For this assessment, rigid structures serve as the models. Treatments inside tents probably occurred to some extent, but investigators did not specifically address this, as they had no reason to believe that the exposures would be any higher in tents versus rigid structures. The clothing scenarios and PPE levels used are identical to those described previously for ECs, and the associated assumptions are the same.

Compliance with PPE requirements may have been better for servicemembers applying bendiocarb WP than it was for servicemembers applying ECs. One hundred percent of servicemembers reportedly wore adequate PPE (Table 13). This is based on a relatively high proportion of servicemembers reporting (86%); however, only 14 interviewees provided information. Fourteen percent of interviewees (i.e., two interviewees) did not respond to this question. Furthermore, as with ECs, "adequate" PPE was not defined in the interviews. Finally, investigators assumed the most exposed were the least protected.

Table 74 presents the assumptions for application of bendiocarb WP. Investigators used the following equation[300] to calculate the weight of active ingredient handled daily:

WA

= VS x FC x WD
CS x 100

where,

WA = weight of active ingredient handled daily
VS = volume of spray prepared daily
FC = finished concentration
WD = density of water
CS = concentration of active ingredient in formulation

All other equations used in dose calculations are provided in the associated tables in the following subsections.

Table 74. Bendiocarb, 76% solid (WP) assumptions for applicationa

Factor Units Definition/Explanation

Assumptions by Level

Source/Rationale

Low

Medium

High

EP

--

Exposure point

Outdoor

Indoor

Indoor

TIM24;[301] PM interviews
UE

mg/lb a.i.

Unit dermal exposure

8.6

8.6

100[302]

1998 PHED Guide: handwand sprayer[303]
UIE

mg/lb a.i.

Unit inhalation exposure

0.11

0.11

1.1

1998 PHED Guide: handwand sprayer[304]
VS

gal/d

Volume of spray prepared daily

1

5

15

PM interviews[305]
FC

% a.i.

Finished concentration

0.25

0.25

0.25

TIM 24[306]
WD

lb/gal

Density of water

8.34

8.34

8.34

TIM 24[307]
CS

lb/lb

Concentration of active ingredient in formulation

0.76

0.76

0.76

Nor-Am[308]
WA

lb a.i./d

Weight of a.i. handled daily

0.027

0.14

0.41

Equation in text.
ET

h/d

Exposure time

1

1

3

PM interviews
EF

d/mo

Exposure frequency

1

6

12

PM interviews
ED

mo

Exposure duration

1

4

7

PM interviews
ABS

--

Dermal absorption factor

0.06

0.06

0.06

Hayes et al.[309]
a) A dash ("--") indicates that the item is not applicable.

2.  Bendiocarb Doses – Application

Table 75 presents doses potentially resulting from exposure during application of bendiocarb WP. Three types are presented for the evaluation of noncarcinogenic effects: PDRD, ADD, and PDRI. No doses are presented for the evaluation of carcinogenic effects, as such activity is unlikely with bendiocarb WP.

Table 75. Bendiocarb, dose rates – application, for evaluation of noncarcinogenic effectsa

Formulation Exposure
Group
Exposure
Point
ABS

Handwand Sprayer

PDRD
(mg/kg/d)

ADD
(mg/kg/d)

PDRI
(mg/kg/d)

Bendiocarb,
76% solid (WP)
Low

Outdoor

0.06

3.92E-02

2.35E-03

4.31E-04

Medium

Indoor

0.06

1.96E-01

1.18E-02

2.16E-03

High

Indoor

0.06

5.88E-01

3.53E-02

6.47E-03

Bendiocarb,
76% solid (WP)
Formulasb:
(1) PDRD = (UE x WA)/BW
(2) ADD = PDRD x ABS
(3) PDRI = (UIE x WA)/BW
a) ABS = dermal absorption factor.
PDRD = potential dose rate for dermal contact.
ADD = absorbed dermal dose.
PDRI = potential dose rate for inhalation.
UE = unit dermal exposure.
WA = weight of a.i. handled.
BW = body weight.
UIE = unit inhalation exposure.
b) Formulas 1 and 3 adapted from EPA, 1997.[310]

3.  Post-Application Scenarios

The post-application scenarios below address servicemembers who were exposed to bendiocarb WP on surfaces inside latrine facilities. Dermal exposure is the only consequential exposure route, as the vapor pressure of bendiocarb is 4.95E-06 mm Hg @ 25oC.[311] OPP typically evaluates inhalation for post-application exposure only for pesticide active ingredients having a vapor pressure of greater than or equal to 1E-05 mm Hg.[312] Investigators presumed opportunities for dermal contact in the mess to have been minimal, given that the only treated surfaces were normally limited to the intersections of walls and floors.

The application assumptions for the model mess and latrine facilities have been described previously (see Post-Application Scenarios for ECs, Section B.3.G.2.a,   Common Elements). Other assumptions related to post-application dermal exposure also are the same as described previously for ECs.

As with ECs, outdoor exposure was not estimated, as investigators presumed it to have been inconsequential based on the PM exposure interviews. Bendiocarb WP was likely applied outdoors around building and tent foundations, and around garbage containers. This would have provided little or no opportunity for post-application exposure.

Table 76 presents the formulation-specific assumptions used for the post-application exposure assessment of bendiocarb, 76% solid (WP). Values are presented for the medium and high exposure levels associated with indoor exposure.

Table 76. Bendiocarb, 76% solid (WP) assumptions for post applicationa

Factor Units Definition/Explanation

Assumptions by Level

Source/Rationale

Low

Medium

High

EP

--

Exposure point

Outdoor

Indoor

Indoor

TIM 24;[313] PM interviews
AR

mg a.i. /cm2

Application rate

--

7E-03

7E-03

EPA[314]
DT

mg a.i. /cm2

Dislodgeable transferable residue; assumed to be 10% of the spray applied

--

7E-04

7E-04

EPA[315]
ETM

h/d

Exposure time for mess

--

2

2

EPA[316]
ETL

h/d

Exposure time for latrine

--

0.5

0.5

EPA[317]
EF

d/mo

Exposure frequency

--

6

12

PM interviews
ED

mo

Exposure duration

--

4

7

PM interviews
ABS

--

Dermal absorption factor

--

0.06

0.06

Hayes et al.[318]
a) A dash ("--") indicates inconsequential exposure, or that the item is otherwise not applicable.

4.  Bendiocarb Doses – Post Application

Table 77 presents doses potentially resulting from the post-application exposure to bendiocarb WP. There are two types of doses presented for the evaluation of noncarcinogenic effects: PDRD and ADD. No doses are presented for the evaluation of carcinogenic effects, as such activity is unlikely with bendiocarb WP.

Table 77. Bendiocarb, dose rates – post application, for evaluation of noncarcinogenic effectsa

Formulation

Exposure
Group

Exposure
Point

ABS

PDRD
(mg/kg/d)

ADD
(mg/kg/d)

Bendiocarb,
76% solid (WP)
Low

Outdoor

0.06

--

--

Medium

Indoor

0.06

3.79E-01

2.28E-02

High

Indoor

0.06

3.79E-01

2.28E-02

Bendiocarb,
76% solid (WP)
Formulasb:
(1) PDRD = S(DT x TF x SA)/BW
(2) ADD = PDRD x ABS
a) ABS = dermal absorption factor.
PDRD = potential dose rate for dermal contact (latrine only).
ADD = absorbed dermal dose (latrine only).
A dash ("--") indicates that the item is not applicable.
DT = dislodgeable transferable residue.
TF = transfer factor.
SA = surface area available for dermal contact.
BW = body weight.
ET = exposure time (mess and latrine).
b) Formula 1 is adapted from EPA.[319]


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