Document ID: EPA-HQ-OPP-2006-0986-0018
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-06-10T04:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460      

	OFFICE OF PREVENTION, PESTICIDE

	AND TOXIC SUBSTANCES

	

  SEQ CHAPTER \h \r 1 MEMORANDUM

Date: February 17, 2009

SUBJECT: Allethrins: Addendum to the Revised Occupational and
Residential Exposure

	        Assessment for the Reregistration Eligibility Decision (RED).
[PC Codes 004003; DP Barcode D359479]

 

PC Code:  004003	DP Barcode:   D359479

Decision No.: None	Registration No.: 21165-62

Petition No.: None	Regulatory Action: Addendum

Risk Assessment Type: Single Chemical	Case No.: None

TXR No.: None	CAS No.: None

MRID No.: None	40 CFR: NA

		              								Ver.Apr.08

          	

FROM:	Matthew Lloyd	

		Risk Assessment Branch 7

		Health Effects Division (7509P)  SEQ CHAPTER \h \r 1 

		

THROUGH:	Michael Metzger

		Risk Assessment Branch 7

		Health Effects Division (7509P)  SEQ CHAPTER \h \r 1 

TO:		Molly Clayton, Chemical Review Manager

		Special Review and Registration Division (7508P)

Attached is an addendum to the Revised Occupational and Residential
Exposure and Risk Assessment document for the allethrins HED RED
Chapter.  This addendum addresses one allethrins product that were
identified subsequent to the revised ORE document document (T. Dole,
D340744; 6/27/07), specifically a product identified for use with
automated misting systems.

 Table of Contents

  TOC \o "1-3" \h \z \u    HYPERLINK \l "_Toc221360594"  Review of Human
Research	  PAGEREF _Toc221360594 \h  4  

  HYPERLINK \l "_Toc221360595"  1.0	Hazard Identification	  PAGEREF
_Toc221360595 \h  5  

  HYPERLINK \l "_Toc221360596"  1.1	Acute Toxicology Categories	 
PAGEREF _Toc221360596 \h  5  

  HYPERLINK \l "_Toc221360597"  1.2	Toxicological Endpoints	  PAGEREF
_Toc221360597 \h  5  

  HYPERLINK \l "_Toc221360598"  2.0	Summary of Use Patterns and
Formulations	  PAGEREF _Toc221360598 \h  6  

  HYPERLINK \l "_Toc221360599"  2.1	Application Rates	  PAGEREF
_Toc221360599 \h  7  

  HYPERLINK \l "_Toc221360600"  3.0	Occupational Handler Exposure and
Risk	  PAGEREF _Toc221360600 \h  7  

  HYPERLINK \l "_Toc221360601"  3.1	Occupational Handler Risk
Characterization	  PAGEREF _Toc221360601 \h  8  

  HYPERLINK \l "_Toc221360602"  4.0	Occupational Post Application
Exposure and Risk	  PAGEREF _Toc221360602 \h  8  

  HYPERLINK \l "_Toc221360603"  4.1	Occupational Post-application
Exposure Data Sources	  PAGEREF _Toc221360603 \h  9  

  HYPERLINK \l "_Toc221360604"  4.2	Occupational Post-application
Assumptions and Calculation Methods	  PAGEREF _Toc221360604 \h  9  

  HYPERLINK \l "_Toc221360605"  4.3	Occupational Post-application
Exposure and Risk Estimates	  PAGEREF _Toc221360605 \h  9  

  HYPERLINK \l "_Toc221360606"  4.4	Occupational Post-application Risk
Characterization	  PAGEREF _Toc221360606 \h  10  

  HYPERLINK \l "_Toc221360607"  5.0	Residential Handler Exposure and
Risk	  PAGEREF _Toc221360607 \h  10  

  HYPERLINK \l "_Toc221360608"  6.0	Residential Post-application
Exposures and Risks	  PAGEREF _Toc221360608 \h  10  

 

Appendices

A - 	Space Spray Occupational and Residential Exposure and Risk
Calculations for Allethrins	

B - 	Time Metered Device Occupational and Residential Exposure and Risk
Calculations for Allethrins	

		  SEQ CHAPTER \h \r 1 Executive Summary

Background and Purpose

  SEQ CHAPTER \h \r 1 This occupational and residential exposure and
risk assessment is being conducted as part of an addendum to EPA’s
human health risk assessment for the Allethrins Reregistration
Eligibility Decision (RED).  This document addresses the exposures and
risks associated with occupational and residential exposure to
allethrins based on label prescribed uses. 

An additional product (21165-62) has been identified that can be used
for either indoor or outdoor use as a space spray using equipment such
as an automated misting system or commercially available handheld fogger
equipment. While the use of this product as a space spray was covered
under the occupational scenarios assessed in earlier documents [e.g.,
D340744; 6/27/07], the product’s use as an automated misting system
was not assessed. 

This revised occupational and residential exposure chapter updates the
assessed exposure scenarios to cover the uses on this newly identified
product label.	

Hazard Identification

Allethrins are of low to moderate acute toxicity (i.e. acute toxicity
category III or II) for oral exposures and they are of low toxicity
(i.e. acute toxicity category III and IV) for dermal and inhalation
exposures.  Allethrins cause minor skin or eye irritation (acute
toxicity category III and IV) and they are not dermal sensitizers.

Toxicity e  SEQ CHAPTER \h \r 1 ndpoints were selected for inhalation
and incidental oral exposure assessment. No endpoints were selected for
dermal exposure assessment because no effects were observed at the limit
dose in the dermal toxicity studies and because of negligible absorption
(0.22 %) of a structurally related chemical (pyrethrin) measured in
human studies. The toxicity endpoints and points of departure (PODs) are
summarized below:   

A NOAEL of 1.3 mg/kg/day was selected as a point of departure (POD) from
a 28 day inhalation study in rats during which clinical signs (limb
tremors, hunched posture, vocalization during handling) were observed at
a LOAEL of 6.5 mg/kg/day.  This endpoint is applicable to short,
intermediate and long term inhalation exposure assessment.

A NOAEL of 20 mg/kg/day was selected as a POD from a 30 day oral study
in dogs during which liver toxicity was observed at a LOAEL of 63
mg/kg/day.  This endpoint is applicable to short term incidental oral
exposure assessment.

A Benchmark Dose of 8 mg/kg/day was selected as a POD from a 6 month
oral study in dogs during which liver toxicity was observed at a LOAEL
of 36 mg/kg/day. The NOAEL is 6 mg/kg/day.  This endpoint is applicable
to intermediate term incidental oral exposures.

The level of concern (LOC) for residential inhalation exposures is an
MOE of at least 1000 which includes the standard uncertainty factors of
10X for inter-species extrapolation and 10X for intra-species variation
as well as a database uncertainty factor of 10X to account for the
possible difference in toxicity between adults and children.  The level
of concern for occupational inhalation exposures is an MOE of at least
100 because the database uncertainty factor does not apply to
occupational exposures.  

 

Occupational Exposure and Risk

  SEQ CHAPTER \h \r 1 

Based on toxicological criteria and potential for exposure, inhalation
exposures were assessed for the applicable occupational handler and
post-application scenarios.  Dermal exposures were not assessed because
no systemic effects were observed at the limit dose in dermal toxicity
studies in animals.  

	The occupational handler exposure scenarios that were assessed were
space spray applications using handheld foggers.  The handheld fogger
scenario demonstrates a risk of concern with an MOE of 8. Risk estimates
indicate that occupational handlers need to wear a fit-tested air
purifying respirator with PF50 to achieve an MOE that does not
demonstrate a risk of concern. This is a level of respiratory protection
significantly greater than typically presented as a potential mitigation
measure by HED. 

	Occupational post-application inhalation exposures have been assessed
for the automated misting system (animal barn) scenario.  Based upon the
label requirement that applications can be made on an up to hourly
basis, worker exposures were assumed to begin in the morning immediately
after the night time applications ceased and were averaged over an eight
hour period.  The resulting MOE is 245, which does not demonstrate a
risk of concern for the scenario. This MOE is conservative because it is
assumed that the aerosols would remain airborne until they were removed
by ventilation and the effects of aerosol settling are not considered.  

Residential Exposure and Risk

 

	 No residential handler exposure scenarios are applicable for this
label, and therefore no exposure assessment was completed. This document
covers a product label that has two uses; a space spray and use in a
automated misting system. The previous assessment (D340744) covers the
residential space spray use identified on the product label; risk
estimates do not demonstrate risks of concern.  

	HED has no current policy to assess exposure for members of the general
public exposed to pesticidal active ingredients used in commercial barn
and stable misting systems. However, it is relevant to note that because
of the different levels of concern between occupational and residential
postapplication exposure (MOEs of 100 and 1000, respectively) that the
current occupational postapplication scenario demonstrates a risk of
concern when compared to the residential (i.e., non-occupational)
postapplicaton level of concern.

Review of Human Research

This risk assessment relies in part on data from studies in which adult
human subjects were intentionally exposed to a pesticide or other
chemical.  These studies, which comprise the Pesticide Handlers Exposure
Database (PHED), have been determined to require a review of their
ethical conduct, and have received that review. The studies in PHED were
considered appropriate (or ethically conducted) for use in risk
assessments.

1.0	Hazard Identification

1.1	Acute Toxicology Categories

The acute toxicity data for allethrins are summarized in   SEQ CHAPTER
\h \r 1 Table 1.  Allethrins are of low to moderate acute toxicity (i.e.
Tox category III or II) for oral exposures and they are of low toxicity
(i.e. toxicity category III and IV) for dermal and inhalation exposures.
 Allethrins cause minor skin or eye irritation (Tox III and IV) and they
are not dermal sensitizers.	

Table   SEQ Table \* ARABIC  1  – Acute Toxicity of Allethrins

Guideline

 No.	Study Type	Bioallethrin	Esbiol	Esbiothrin	Pynamin Forte

870.1100	Acute Oral	III	II	II	III

870.1200	Acute Dermal 	III	III	III	III

870.1300	Acute Inhalation 	IV	III	III	IV

870.2400	Primary Eye Irritation	III	III	IV	III

870.2500	Primary Skin Irritation 	IV	IV	III	IV

870.2600	Dermal Sensitization	negative	negative	negative	negative

1.2	Toxicological Endpoints

  SEQ CHAPTER \h \r 1  The points of departure (PODs) that were used to
complete this assessment are summarized in Table 2.  PODs were selected
only for incidental oral and inhalation exposures.  No PODs were
selected for dermal exposure because no effects were observed at the
limit dose in the dermal toxicity studies and because of negligible
absorption (0.22 %) of pyrethrin, which is a structurally related
chemical, measured in human studies.  

	The POD for intermediate term incidental oral exposure was selected
based upon a benchmark dose analysis because of the 6x difference
between the POD (NOAEL of 6 mg/kg/day) and the LOAEL (36 mg/kg/day).  A
10% response for the bench mark dose (i.e. BMD10) was selected because
of the mild nature of the lesions, characterized as "acute swelling of
hepatocytes", which did not progress in severity at the high dose.  The
lesions were accompanied by increased relative liver weight and moderate
increases in alkaline phosphatase in males.  The selected BMDL10 value
was 267 ppm, which is lower 95% confidence limit on the BMD10.   This
dietary concentration was converted to a mg/kg/day dose by using the
dose in males, which was lower than that in females:  267 ppm/200 ppm x
6.1 mg/kg/day = 8 mg/kg/day.  

The level of concern for residential incidental oral and inhalation
exposures is an MOE of 1000.  This includes the standard uncertainty
factors of 10 for interspecies extrapolation and 10 for intraspecies
variation as well as a database uncertainty factor of 10X to account for
the possible difference in toxicity between adults and children.  The
LOC for occupational inhalation exposures is an MOE of 100 because the
database uncertainty factor does not apply to occupational exposures.   



Table   SEQ Table \* ARABIC  2  –PODs for Assessing Occupational and
Residential Risks for Allethrins

Exposure Scenario	Point of Departure (POD)	Target MOE	Study and
Toxicological Effects

Incidental Oral 

Short Term 

(1 - 30 days)	NOAEL = 20 mg/kg/day

	Residential  = 1000*

Occupational = N/A	30-day dog  (Esbiothrin)

LOAEL = 63 mg/kg/day based on elevated liver enzymes and increased liver
weight.

Incidental Oral 

Intermediate Term 

(1 - 6 months)	BMDL10 = 8 mg/kg/day

	Residential  = 1000*

Occupational = N/A	6 month dog  (Bioallethrin)

LOAEL = 36 mg/kg/day based on microscopic liver changes (hepatocellular
degeneration). NOAEL = 6 mg/kg/day.

Dermal

(All populations)	N/A - No systemic toxicity at 1000 mg/kg/day with
Esbiothrin or Esbiol and negligible dermal absorption with pyrethrins
(0.22%). 

Inhalation 

(All populations)

All durations	NOAEL = 1.3 mg/kg/day

	Residential  = 1000*

Occupational = 100	28-day inhalation study in rats (Esbiol) LOAEL = 6.5
mg/kg/day based on clinical signs in females (limb tremors, hunched
posture, vocalization during handling)

Cancer	Classification:  Suggestive Evidence of Carcinogenicity, but Not
Sufficient to Assess Human Carcinogenic Potential

* Includes a Database UF of 10x to account for the possible difference
in toxicity between adults and children  

2.0	Summary of Use Patterns and Formulations

This addendum document covers a single product (Pyranha 1-10 SBA
Concentrate (21165-62); a liquid concentrate for use indoors in horse
barns/dog kennels/zoo animal quarters or outdoors as a space spray
around homes, patios, pool areas, and lawn areas. 

The Revised Allethrins Occupational and Residential Exposure Assessment
for the Reregistration Eligibility Decision (RED) [D340744; 6/27/07]
identify the uses of allethrins at occupational and residential uses
sites. Allethrins are a mixture of synthetic pyrethroid insecticides
that are structurally related to natural pyrethrum.  They cause
immediate, but temporary paralysis of the target insects.  They are
usually used with a synergist such as piperonyl butoxide that prevents
insect recovery.  Allethrins are used for commercial, horticultural and
residential applications.  



2.1	Application Rates

  SEQ CHAPTER \h \r 1 

The application rates for all allethrins products can be found in
Revised Occupational and Residential Exposure Assessment for the
Reregistration Eligibility Decision (RED) [D340744]. This addendum
addresses a single label; Pyranha 1-10 SBA Concentrate (21165-62). The
application rates for that label can be found below in Table 3.

Table 3 – Pyranha 1-10 SBA Concentrate Application Rates

Product Type	Label Identification	Application Type	Use Sites

	Spray Dilution / Application Rate

(Percent ai)

Concentrate	21165-62	Fogger spray application 	CIU for application
around homes, patios, tennis courts, pool areas, beach houses, lawn
areas 	0.55% ai (concentrate)

0.0003% (product spray solution)

Metered Release Aerosol	21165-62	Time Metered Aerosol	CIU for use as an
indoor  space spray in horse barns, dog kennels, and zoo animal quarters
0.0003% (product spray solution)

CIU    = Commercial Industrial Use

3.0	Occupational Handler Exposure and Risk

  SEQ CHAPTER \h \r 1 	

 The term “handler” applies to individuals who mix, load, and apply
the pesticide product.  

While the 21165-62 label allows for use and application as a space
spray, those uses are adequately assessed in the revised exposure
assessment document completed for allethrins on June 27, 2007 (D340744).
  However, the space spray label rate for product 21165-62 is assessed
in this document to provide a complete assessment of this specific
product label.

Only inhalation exposures have been assessed because no systemic effects
were observed at the limit dose in the dermal toxicity studies in test
animals and no toxicity endpoint was selected for dermal exposure.  The
LOC is an MOE of 100 for short, intermediate and long term inhalation
exposures.

Outdoor Space Sprays (i.e. fogging) Applications Assumptions:	

  SEQ CHAPTER \h \r 1 The following assumptions were used in estimating
risks to occupational handlers from exposure to allethrins during space
spray application:

The fogger applicator would be exposed to the average of the initial
concentration and the application rate concentration during hand held
fogging.

The spray dilution for this product label is 0.05.

The initial concentration is 0 mg/m3 based on the assumption that
allethrin residues from previous applications have dispersed or settled
out on surfaces.

The application rate concentration is 6 mg/m3 based upon the application
of 1.0 ounce of diluted spray per 1000 cubic feet based upon product
labels.

The breathing rate is assumed to be 1 m3/hr for an adult occupational
handler.

The applicator will be exposed to average concentration for 240 minutes
per 480 minute work day with the unexposed time being spent in transport
and equipment setup (i.e., exposure time per day is 4 hrs.). 

Space Spray  Applications Calculation Methods:

The above assumptions were used to calculate a daily inhalation exposure
and risks as detailed in Appendix A.   A POD of 1.3 mg/kg/day was used
to calculate inhalation exposure and a LOC of 100 is applicable.

The risks for the space spray applications are summarized in Table 4. 
The risk estimates demonstrate a risk of concern when no respiratory
protection is assessed.  The risk estimates no longer demonstrate a risk
of concern when fit-tested air purifying respirators with appropriate
cartridges are worn (i.e., a protection factor of 50). 

Table 4 – Occupational Handler Risks from Space Spray Applications 

Label #	Spray Dilution	Application Rate 

(lbs ai/1000 ft3)*	Average Air Concentration

(mg/m3)	Respirator Worn	Inhalation MOE

(all exposure durations)

21165-62	0.05	0.0003	3	No respiratory protection	8

21165-62	0.05	0.0003	3	Air Purifying  respirator providing (PF10) 	75

21165-62	0.05	0.0003	3	Air Purifying respirator providing (PF50)	380

MOEs highlighted in bold font indicate risks of concern because they are
below an MOE of 100 (occupational LOC).

* Concentrate is diluted 1/21 and the concentrate has 0.5% ai
allethrins; 0.0003 lbs ai/1000 ft3.

3.1	Occupational Handler Risk Characterization

	Usually occupational handler exposure assessments are completed by HED
using different levels of risk mitigation.  Because risk estimates
demonstrate risks of concern for baseline inhalation exposure and
additional respiratory protection, HED has presented risk estimates for
air purifying respirators with a protection factor of 50 (PF50). HED
does not typically assess occupational handler scenarios with
respiratory protection factors above a protection factor of 10 (i.e.,
PF10). 

	Inhalation risk estimates for the air purifying respirator scenarios
assessed assume that 1) the workers donning the respirators have been
properly trained on their use and 2) the respirators are fit-tested to
the occupational handler. The two points above are implicit in the risk
estimates that HED presents in this document. 

4.0	Occupational Post Application Exposure and Risk

	Pyranha 1-10 SBA Concentrate (21165-62) can be applied either through a
time metered device or as a space spray using commercially available
handheld equipment. The Pyranha 1-10 SBA Concentrate product label
indicates the automated space spray can have repeat treatments at one
hour intervals to maintain pest control. 

4.1	Occupational Post-application Exposure Data Sources 

No exposure data was available to assess post application exposures so
standard HED assumptions and label information was used to assess
occupational postapplication risk.

4.2	Occupational Post-application Assumptions and Calculation Methods

The Pyranha 1-10 Concentrate label is registered for horse barns, dog
kennels, and zoos. 

Assumptions for Automated Misting Systems [animal barns];

(Pyranha 1-10 SBA Concentrate label #21165-62):

The following assumptions were used in estimating risks to workers from
post-application exposure to allethrins:

The Pyranha product (21165-62) is applied at one hour intervals for up
to 24 hours per day in accordance with the label.

The initial concentration of 0.29 mg/m3 is based upon one one minute
spray with a nozzle flow rate of 1 ounce of spray dilution delivered per
minute; 0.55% allethrin applied for each 1000 cubic foot space.

The air exchange rate is 6 air changes per hour based on a 30,000 cubic
foot building volume with a ventilation rate of 3000 CFM.   

The daily exposure is based on the average allethrins air concentration
(in mg/m3) for the eight hour occupational assessment duration. 

The breathing rate is 1.0 m3 per hour and the exposure time is eight
hours per day.

Calculation Methods

Pyranha 1-10 SBA Concentrate label (#21165-62)

	For the Pyrahna product, the horse barn scenario assumes that a one
minute spray event occurs every 60 minutes (per the label
specifications). According to those inputs, the allethrin air
concentration rises up to the four hour mark (240 minutes) and then
holds relatively constant for the remainder of the 8 hour (480 minute)
exposure duration. The building volume is assumed to be 30,000 cubic
feet, with a ventilation rate of 3000 CFM. The resulting air exchange
during the 8 hour occupational duration is 6 air changes per hour for
the barn scenario.     

4.3	Occupational Post-application Exposure and Risk Estimates

The exposure and risk estimates for post-application exposures are
detailed in Table B1 Appendix B. The air concentration profile is also
included. The inhalation MOE for product label 21165-62 is 245, which
does not demonstrate a risk of concern. The LOC for the scenario is an
MOE of 100.  This MOE is representative of a barn space that is
ventilated at the rate of 6 air changes per hour with the maximum
application rate and interval for the product.

4.4	Occupational Post-application Risk Characterization

The risk for the metered release scenario is conservative because it was
assumed that the aerosols would remain airborne until they were removed
by ventilation and the effects of aerosol settling were not considered. 
Aerosol settling could be a major factor depending upon the aerosol size
and rate of evaporation.  Information regarding the aerosol size and
evaporation rate could be used to refine the risks.

	HED notes that typical metered release labels have language indicating
that “Automated spraying systems must not be programmed to release
pesticides when people are in the barn or food or feed are exposed.”
The Pyranha 1-10 SBA Concentrate label has the following label language,
“Personnel should vacate containment areas to be treated while
treatment is in progress.” 

For additional characterization, the label has been assessed assuming
one minute of product spray released every two hours. This application
rate is the maximum application rate with a lower application frequency
than is listed on the current product label.  The inhalation MOE for
product label 21165-62 is 490, which does demonstrate a risk of concern.
The LOC for the scenario is an MOE of 100.  This MOE is representative
of a space that is ventilated at the rate of 6 air changes per hour with
the maximum application rate and one minute of product spray released
every two hours. 

5.0	Residential Handler Exposure and Risk

	The label assessed for this addendum (21165-62) identifies the product
as “for commercial/industrial use only.” Therefore, no residential
handler assessment was completed. Since the label identifies “patios,
around homes, lawn areas…” as use sites, an exposure assessment for
residential post-application assessment for this product label is
appropriate. 

  SEQ CHAPTER \h \r 1   SEQ CHAPTER \h \r 1 	6.0	Residential
Post-application Exposures and Risks

	The term “post-application” describes individuals who are exposed
to pesticides after entering areas previously treated with pesticides. 

Outdoor Space Sprays:

	A residential post-application assessment is appropriate for the space
spray use identified on label 21165-62. The allethrins assessment
(D340744) covers the residential post-application scenario within the
use rate specified on the label. In the exposure assessment, short- and
intermediate-term inhalation risk estimates do not demonstrate risks of
concern (i.e., all post-application inhalation MOEs for allethrins space
sprays exceed the LOC of 1000).  

	Since the Pyranha 1-10 SBA Concentrate label is registered for outdoor
space spray applications, HED finds it appropriate to conduct a
post-application dermal and incidental oral assessment because of
aerosol deposition after treatment. The allethrins exposure assessment
(D340744) covered a scenario for incidental oral ingestion risks to
toddlers playing on indoor surfaces after surface treatment by a PCO
based on NDETF data and a higher application rate than the one on the
Pyrahna product label. Short-term incidental oral risk estimates for
toddlers did not demonstrate risks of concern. Since the Pyrahna product
is labeled for outdoor use there are differences between the two
scenarios although there are two factors that make this a conservative
comparison; 1) the application rate for the Pyrahna product is lower
than the indoor application rate assessed previously (0.000016 lb
ai/1000 ft3   outdoor vs. 0.0042 lb ai/1000 ft3 indoor)  and 2) since
the Pyrahna product is applied outdoors as a fogger instead of indoors
as a PCO broadcast, there is additional dilution and ambient air
movement that reduces exposure potential for a toddlers to this exposure
scenario. HED believes that the risk to toddlers for the Pyrahna product
is less than MOEs of 1200 (for carpet) and 1700 (for vinyl) reflect for
the short-term indoor incidental oral risk estimates in the previous
allethrins exposure assessment (D340744) reflect.  

Automated Misting Systems (animal barns):

While the product label does indicate that the product is for commercial
and industrial use in horse barns, dog kennels, and zoo quarters, that
does not preclude what HED considers “residential” (i.e.,
non-occupational) exposure. Commercial horse barns and dog kennels can
be frequented by a non-occupational group. For instance, some people
board their horses at commercial stables. HED is currently revising the
residential Standard Operating Procedures (SOPs) and is considering
assessing post-application exposure for those who may be exposed to this
scenario.

	Currently, HED does not have an SOP to assess residential
post-application exposure for the “hobby barn” scenario.  While the
assumptions in the occupational exposure scenario (i.e., 8 hours spent
in the barn) are likely an overestimate of risk, HED has no information
at this time to characterize the amount of time horse owners that board
their horses in commercial stables. It is important to note that if the
occupational post-application scenario is considered compared to the
residential post-application level of concern (an MOE of 1000), the
scenario results in a risk estimate demonstrates a risk of concern for
the general population.	



Appendix A – Space Spray Occupational and Residential Exposure and
Risk Calculations 

for Allethrins



Table A1 – Allethrin Inhalation MOE’s for Occupational Handlers
Applying Space Sprays 

Label #	Spray Dilution	Application RateB 

(lb ai/1000 ft3)	Initial Concentration 

(mg/m3)	Final Concentration

(mg/m3)	Average Concentration

(mg/m3)	Inhalation ExposureC (mg/day)	Inhalation DoseD

(mg/kg/day)	Inhalation MOEE

No Respirators Worn (i.e. PF =1)

21165-62	0.05	0.0003A	0	6	3	12	0.17	8

Respiratory Protection (PF = 10)

21165-62	0.05	0.0003A	0	6	3	1.2	1.2	76

Respiratory Protection (PF = 50)

21165-62	0.05	0.0003A	0	6	3	0.24	0.003	380

Footnotes:

A.    This rate is lower than the assessed rates for space sprays in the
Revised ORE document [D340744], and is included only for reference.

B.	Based upon the application of 1 fluid ounce per 1000 cubic feet. [The
concentrate is diluted 1/21 and the concentrate has  0.5% ai].

C.	Inhalation Exposure (mg/day) = [Average Concentration (mg/m3) *
Breathing Rate (1 m3/hr) * Exposure Time (4 hours/day)] / [Respirator
Protection Factor (1, 10 or 50)] 

D.	Inhalation Dose (mg/kg/day = Inhalation Exposure (mg/day) / Body
Weight (70 kg)

E.	MOE = POD/Dose where the NOAEL is 1.3 mg/kg/day. 

* The LOC is an MOE is 100.  MOEs that are less than 100 indicate risks
of concern and are highlighted in bold font.

	



Appendix B – Metered Release (Automated Misting Systems) Occupational
and Residential Exposure and Risk Calculations 

for Allethrins



Appendix B - Allethrins Post-application Risk from Time Metered Device
Applications

Assuming one release for one minute every hour in a horse barn (Pyranha
1-10 SBA Concentrate, 21165-62)

Application Parameters 	Ventilation Parameters	Inhalation Exposure and
Risk

% AI	0.55	Building Volume 	30,000	CF (cubic feet)	8 Hour Average Air
Concentration (mg/m3)	0.09

Spray Dilution	0.05	Ventilation Rate	3000	CFM	Breathing Rate (m3/hr)	1

Nozzle Flow Rate	1	Air Changes per Hour	6	ACH	Exposure Time (hours/day)
8

Nozzle Coverage	1000

Body Weight (kg)	70

Spray Density	8.33

Dose (mg/kg/day)	0.005

Application Rate lb/1000 cf/minute spray	0.000016

POD (NOAEL)	1.3

Spray Duration (minutes)	1

MOE	245

Application Rate per Release (lb/1000 cf)	0.000016

* The LOC is an MOE of 100 for inhalation exposures.  MOEs that are less
than 100 indicate risks of concern and are highlighted in bold font.

Convert to mg/1000 ft3	7.3

Convert 1000 ft3 to m3	28.3

Initial Air Concentration (mg/m3)	0.259

Appendix B2 - Allethrins Post-application Risk from Time Metered Device
Applications

Application Parameters 	Ventilation Parameters	Inhalation Exposure and
Risk

% AI	0.55	Building Volume 	30,000	CF	8 Hour Average Air Concentration
(mg/m3)	0.02

Spray Dilution	0.05	Ventilation Rate	3000	CFM	Breathing Rate (m3/hr)	1

Nozzle Flow Rate	1	Air Changes per Hour	6	ACH	Exposure Time (hours/day)
8

Nozzle Coverage	1000

Body Weight (kg)	70

Spray Density	8.33

Dose (mg/kg/day)	0.003

Application Rate lb/1000 cf/minute spray	0.000016

POD (NOAEL)	1.3

Spray Duration (minutes)	1

MOE	490

Application Rate per Release (lb/1000 cf)	0.000016

* The LOC is an MOE of 100 for inhalation exposures.  MOEs that are less
than 100 indicate risks of concern and are highlighted in bold font.

Convert to mg/1000 ft3	7.3

Convert 1000 ft3 to m3	28.3

Initial Air Concentration (mg/m3)	0.259

Assuming one release for one minute every 2 hours in a horse barn
(Pyranha 1-10 SBA Concentrate, 21165-62)

 “Horse Stable Ventilation” ;The Pennsylvania State University
Agricultural And Biological Engineering Extension. Available:
http://pubs.cas.psu.edu/freepubs/pdfs/ub039.pdf

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