Document ID: EPA-HQ-OPP-2002-0302-0192
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2007-12-05T05:00Z

Policy

Science Advisory Council for Exposure

Policy Number:	12

Regarding:	Recommended Revisions to the Standard Operating Procedures
(SOPs) for Residential Exposure Assessments 

Date:		Original: December 18, 1997;  Revised: February 22,  2001

Index terms:	Dermal exposure, turf, carpets, indoor surfaces,
non-dietary ingestion, handler exposure input values 

Contact:	Deborah. Smegal, Jeff Dawson, Jeff Evans

ISSUE:	

This policy is a revision of key input variables presented in the,
Standard Operating Procedures for Residential Exposure Assessments,
dated December 18, 1997.  It provides recommended values for addressing
post application dermal, inhalation and non-dietary ingestion routes of
exposure to lawn care pesticides, indoor broadcast treatments and crack
and crevice treatments.   This policy also includes revised assumptions
for “area treated” when conducting a residential handler assessment.

BACKGROUND:	

This policy is a result of discussions in HEDs Exposure Science Advisory
Council (Expo SAC) and should be used in conjunction with the current
residential SOPs.  Key post application variables presented in the
revised policy include transfer efficiency (percent transferable residue
assumptions for turf, carpet and vinyl treatments) and transfer
coefficients.   The revised inhalation values reflect the available
information presented in the Agency’s Exposure Factors Handbook.  The
transfer efficiency values address the transfer of pesticide residues to
wet hands for use in non-dietary ingestion assessments and also reflect
a reasonable worse case dermal exposure estimate when used with the
revised transfer coefficients in dermal exposure assessments.  The
document strongly urges assessors to use caution when using Occupational
and Residential Exposure Task Force (ORETF) member Turf Transferable
Residue (TTR) studies with the current transfer coefficients as this
combination may under-predict dermal exposure.   The ORETF has submitted
a post application dermal exposure model for use with member TTR
studies.   This document is under review and will be presented to the
SAC when all the issues are discussed and addressed by the ORETF.

POLICY: 	

Use the following table as a guide for choosing standard values, when no
other supporting data or information are available.



Table 1:  Revised Residential SOP Assumptions

February 2001

Exposure Scenario

 (SOP #)	

Parameter	

Previous Assumption	

Current Assumption	

Source

Residential Postapplication

Hand to mouth  (2.3.2

8.4)

Aggregate SOP 2.3.2. with:

SOP 2.3.3 Object-to-mouth

 and

 

SOP 2.3.4

Soil ingestion	

hand transfer efficiency (fraction of ai available for transfer to hands
from foliage) 	

20%	

5% of application rate available for transfer from treated turf to wet
hands	

The 5% transfer factor is based on data by Clothier (2000).  Clothier
measured percent transfer efficiency  means of  0.156% (Std. Dev
0.138%), 2.72% (Std. Dev. 1.12%) 4.18% (Std  Dev. 1.53%) for the
pesticides chlorpyrifos, chlorothalonil, and cyfluthrin respectively. 
The results are based on a single hand presses of volunteers hands
(wetted with their own saliva) onto St. Augustine turf treated with the
above mentioned pesticides.   These types of transfer efficiency data
are needed to assess the hand-to-mouth exposure pathway when using
hand-to-mouth frequency data based on videotapes or other observational
data as discussed below under frequency.   The wet values were 2 to 3
times higher than similar hand presses performed by  volunteers whose
hands were dry.

	

surface area of hands	

350 cm2	

20 cm2	

This value is based on the following recommendations and assumptions:

1) To address hand-to-mouth exposure, the February 1999 Scientific
Advisory Panel (SAP) suggested that each hand-to-mouth event consists
the insertion of 1 to 3 fingers.   The same SAP also suggested the use
of a palmar surface area (both hands) of 114 cm2 .  This value is
consistent with values reported for children ages 37 to 42 months (111
cm2) and 43 to 48 months (116 cm2) by Snyder (1975).  Children in these
age groups are considered ‘pre-schoolers’ according to the American
Red Cross (1990 Safety Checklist).

2) The problem of assigning surface area values to the palms and fingers
was solved by Gurunathan (1998) who simply dividing the palmar surface
area of the hands by 2, with each half representing the palms and palmar
surface of the fingers.   Since the hand-to-mouth has been defined by
the SAP as 1 to 3 fingers (5.7 to 17.1 cm2 ) a screening level of 20 cm2
was selected based on the assumption that each hand-to-mouth event
equals 3 fingers.  A criticism of hand-to-mouth frequency data based on
video tapes is that it is not clear if the counting of hand-to-mouth
events are based on finger insertions or if the hands were simply
located near the mouth (Kissel et al., 1998).

	

exposure frequency	

1.56 times/hour	

20 times/hour for short-term exposure scenarios and   

9.5 times/hour for intermediate term	

Reed et al., (1999) reported hourly frequencies of  hand-to-mouth events
in pre school children aged 2 to 5 years based on observations using
video tapes.   The data consist of 20 children at daycare centers and 10
children at home.  A range of 0 to 70 events per hour were reported.  
The 1999 SAP recommended the use of the 90th percentile value of 20
events.   A mean of 9.5 events was also reported by Reed, which is 
similar to the mean reported by Zartarian et al., 1995 and 1997 using
similar video tape techniques while observing 4 farmworker children (2-4
years).

	

saliva extraction factor	

100%	

50%	

It has been recognized in the literature that there is incomplete
removal of residues on the hands by hygiene washes using water,
surfactants, ethanol, or isopropanol (Fenske and Lu, 1994; Kissel et
al., 1998; Wester and Maibach, 1989).   These, references suggest
removal efficiency as low as 10%.  Camann et al., 1995, investigated the
use of surgical sponges wetted with human saliva to remove residues from
hands of volunteers.   Removal efficiency of 50 percent by saliva was
reported for the pesticides chlorpyrifos, poperonyl butoxide and
pyrethrin.  Thus, for screening purposes, the value of 50% is
recommended.

	

exposure time	

2 hours	

2 hours	

This is based on the 75th percentile value (i.e., 120 minutes) for
playing on grass for ages 1-4 years and ages 5-11 years (Tsang and
Klepeis 1996 as cited on pg. 15-79 of EPA 1997, Exposure Factors
Handbook, EFH).  The data were truncated at the 75% percentile.  23% of
children ages 1-4 years played on grass more than 2 hours/day (p.
15-78).  In comparison, the 95th percentile for playing outdoors is 3.5
hours, the 95th percentile for time spent on school grounds/playgrounds
is 2.9 hours, while the 95th percentile for time spent at home in the
yard or other areas outside the home is 5.75 hours for children 1-4
years (p. 15-96, 15-124 and 15-136 of EPA EFH, 1997). 

Object to mouth (formerly grass ingestion) (2.3.3)

Aggregate SOP 2.3.3. with:

SOP 2.3.2 Hand-to-mouth

 and

 

SOP 2.3.4

Soil ingestion	

Use dislodgeable foliar residue data, not turf transferable residue data

20%	

Tier 1:

20% of application rate available for transfer to mouth

Tier 2:

Use percent dislodgeable value from chemical specific  DFR data 
available for Ag Crops

Tier 3:

Chemical specific DFR data for turfgrass	

This scenario addresses the mouthing, not eating, of turfgrass that may
be grasped by a child.

The first tier assumption of 20% dislodgeability is based on the large
body of  DFR residue data available for agricultural crops.  These data
rely on the use of a surfactant combined with the mechanical shaking of
treated leaf disc samples.  This process may provide reasonable estimate
of an infant or small child's ability to extract residues from the
leaf/wax matrix. 

As a second tier, chemical specific DFR data available for agricultural
crops may be used since this is more reflective of the
chemical/formulation specific aspects of dislodgeability related to the
pesticide you are evaluating.

If chemical specific DFR data are available for turfgrass, these data
may be used as a third tier.   However, there are limited data available
based on this method.  Available Turfgrass DFR data indicate percent
dislodgeability in the range of 3-5% (e.g. Hurto and Prinster 1993, 
Cowell et al., 1993).   DFRs as low as ~0.5% for semi-volatile (10-4,-5
Torr) pesticides such as DDVP and diazinon were reported by Goh et al.,
1986 and Sears, 1987.

The 50% extraction value (of residues on the hand) is not recommended
for use in this scenario since the saliva extraction value assumption
addresses the removal of residues from the hand, as a result of contact
with the treated turf,  by saliva during the mouthing event. (See SOP
2.3.2.).     

	

surface area 	

	25 cm2/day	

Surface area represents a 2.x2 inches or 4 in2 area and is intended to
represent the approximate area from which a child may grasp a handful of
grass or "mouth" an object such as a toy.  HED believes this represents
an upper-percentile value.  

Dermal Exposure from Lawns (2.2)	

Turf Transferable Residue (TTR)	

20%	

chemical-specific data or 5% of application rate	

There is interdependence of the transferable residue value and the human
activity expressed in the transfer coefficient.   The TC for short term
exposures is based on a study by evaluated by Formoli (1996) of the
California Department of Pesticide Regulation, in which propetamaphos
was applied to carpets.  The transferable residues in that study were
~1% of the application  rate.  The TTR method used to measure concurrent
transferable residues was the California roller (also referred to as the
cloth roller and CDFA roller).  Other proprietary studies using this
method suggest 1.6-3% transferability.  The California EPA, in a letter
to the Agency during the time the SOPs were taken to the SAP also affirm
that the transferability of this method is less than 5%.   

TTR data generated by ORETF members rely on a modified version of the
California roller (ORETF roller) that appears to have a much lower
transfer efficiency (percent of application rate) than the original
version.   Many TTR data submitted by ORETF members show  percent
transferabilities of less than 1% of the application rate for sprayable
formulations and less than  0.5% of the application rate for granular
formulations.   ORD has conducted a round robin test of TTR methods that
included the ORETF roller (Fortune 1997).  While ORD concluded that the
ORETF roller performed the best of all methods, transfer efficiency for
three liquid herbicide formulations indicated a transfer efficiency of
~0.5%.  The ORETF data should not be used with the revised Transfer
Coefficients shown below since these revised TCs are based on TTR
transfer efficiencies of ~1-5% (transfer efficiency = % of the
application rate).   The ORETF is generating task force specific
transfer coefficients to be used with the ORETF member TTR data.   ORETF
post application exposure data has been submitted and is being reviewed.
 

	

turf transfer coefficient (TC)	

43,000 cm2/hr for adults

8,700 cm2/hr for children	

Short-term:

14,500 cm2/hr for adults

5,200 cm2/hr for children (1-6 yrs)	

The TC for short term exposures is based on a review of a study by
Formoli (1996) in which propetamaphos was applied to carpets.  
Individual volunteers wore cotton tights, shirts, socks and gloves and
performed Jazzercise® for a period of 20 minutes.  The normalized
hourly value from this study is 43,000 cm2/hr.  The TC for the 20 minute
duration is (14,500 cm2/20 minutes).   This 20 minute TC was used to
predict results from a biological monitoring study (7 µg/kg/day) based
on exposure to a spray application of 4 pounds per acre (a.i) for 2-4
hour durations (1 µg/kg/day for granular formulation).  This biological
monitoring study is reported in the literature as (Vacarro et al., 1996)
and submitted to the Agency as MRID 430420-03 (liquid) and 441671-01
(granular).   In Vacarro,  individuals performed choreographed
activities ranging from low or no contact (sunbathing and picnicking on
a blanket, 1.5 hours) as well as activities resulting in contact
(crawling, playing frisbee( and touch football, 2.5 hours).   Volunteers
wore short-sleeved shirts and short pants (defined as running attire).  
Enclosed footwear was worn only during the touch football session.  
Bottom line, 20 minutes of Jazzercise = one hour of exposure.  For the
spray example:

 4 lb ai/A (44.8 µg/cm2) x 5% (transfer efficiency) x 14500 cm2/hr x
3%/70 = 13.9 µg/kg/day).

[In Vacarro, a 4 lb ai/acre rate was used.  Chlorpyrifos has a dermal
absorption rate of 3%]

Remember this SOP also requires an exposure duration of 2 hours.

Jazzercise( transfer coefficients are based on total deposition to
outside dosimeters (assuming no clothing protection).  This is why
critics often suggest it is  “children rolling naked on the grass”. 
This  is not an accurate characterization of the TC since the revision
is based on a comparison of the short term study Jazzercise( to longer
term studies with volunteers wearing typical summer clothing performing
high and low to no contact activities.  

	

Intermediate-term:

7,300 cm2/hr for adults

2,600 cm2/hr for children (1-6 yrs)	

Based on Formoli (1996) and Vacarro et al. (1996) as discussed above.  
Bottom line: 20 minutes of Jazzercise = 2 hours of exposure.

	

Exposure duration	

2 hours	

2 hours	

This is based on the 75th percentile value (i.e., 120 minutes) and
121minutes per day  is the value listed for percentiles above the 75th 
percentile for playing on grass for ages 1-4 years and ages 5-11 years
(N 206 and N 185 respectively) Tsang amd Klepeis 1996 as cited on pg.
15-79 of Exposure Factors Handbook, EFH Vol. III, 1997.  The data were
truncated at the 75% percentile.  23% of children ages 1-4 years played
on grass more than 2 hours/day (p. 15-78).

Dermal Exposure from Indoor Pesticide Use (8.2)	

Indoor surface Transferable Residue 	

50%	

5% of application rate–carpets (8.2.1 and 8.4) 

10% of application rate–hard surfaces (8.2.2 and 8.4)	

Camann et al. (1995) - mean wet hand transfer efficiencies (human
saliva) from plush carpets for the respective pesticides chlorpyrifos,
pyrethrin I and piperonyl butoxide  - 1.1% (Std. Dev 0.6%) , 4.8% (Std.
Dev. 2.4%) and 2.8% (0.9%).

Clothier (1999b) - wet palm (human saliva) transfer efficiencies from
new carpet for the respective pesticides chlorpyrifos, pyrethrin I and
piperonyl butoxide - 1.21% (Std. Dev 1.00%), 1.87% (Std. Dev. 1.38%) and
2.03% (Std. Dev. 1.04%).

Clothier (1999b) wet palm (human saliva) transfer efficiencies from used
carpet for the respective pesticides chlorpyrifos, pyrethrin I and
piperonyl butoxide - 0.47% (Std. Dev. 0.38%), 1.64% (Std. Dev. 0.86%)
and 0.87% (Std. Dev. 5.6%).

Clothier (1999a) - wet palm (human saliva) transfer efficiencies from
sheet vinyl flooring for the respective pesticides chlorpyrifos,
pyrethrin I and piperonyl butoxide - 4.38% (Std. Dev 2.83%), 8.89% (Std.
Dev. 4.66%) and 4.06% (Std. Dev. 2.64%).

	

Indoor surface transfer coefficient (TC)	

43,000 cm2/hr for adults

8,700 cm2/hr for children	

Short-and intermediate- term:

16,700 cm2/hr for adults

6,000 cm2/hr for children (1-6 yrs)	

The original TC is from Formoli (1996) as discussed under turfgrass. 
The revision is based on Ross (1990, 1991) where a normalized hourly TC
of 200,000 cm2/hour was measured following 20 minutes of Jazzercise(
(66,666 cm2/20 minutes).   Similar comparisons were made to another
study performed by Vacarro where volunteers performed scripted activites
on treated carpets.  The volunteers wore bathing suits for durations of
4 hours.   Activities include crawling and playing with blocks.  While
this scenario may be unreasonable for adults, it may be reasonable for
young children wearing  diapers. The twenty minute duration TC 66,666 (
4 hrs = 16,700.

	

Exposure duration	

8 hours 	

8 hours for carpets/textile surfaces

4 hours for hard surfaces	

The 8 hour duration of exposure is based on professional judgement for
upper-percentile dermal contact time with treated carpets, or other
textile surfaces (i.e., furniture, bedding) that may contain pesticide
residues as a result of direct application or indirect deposition.  This
assumed 8-hour value is based on the mean total time spent indoors for
young children (1-4 years) of 21 hours (p. 15-147 of EPA EFH 1997), and
subtracting the amount of time spent sleeping, eating, and bathing
(approximately 13 hours).  

The 4 hour value for hard surfaces is based on the 90th percentile
values for time spent in the kitchen and bathroom for all age groups
(adults and children) (p. 15-129 and 15-130, EPA EFH 1997).  The
duration for young children exposure is slightly less.

Inhalation 

(2.0 and 8.3)	

adult hourly inhalation rate for short-term exposures	

0.55 m3/hr (daily rate of 13.3 m3/hr divided by 24 hours)	

rest:  0.4 m3/hr

sedentary activity:  0.5 m3/hr

light activity: 1m3/hr

moderate activity: 1.6 m3/hr	

The hourly inhalation rates for adults are the values recommended by EPA
Exposure Factors Handbook 1997, pg 5-24.  These values should be used to
assess short-term scenarios of a few hours in duration, such as
postapplication inhalation exposures following lawn treatment, foggers
and crack and crevice treatments (depending on chemical-specific data,
such as air measurements, vapor pressure, persistence).  

	

child (1-6 year) hourly inhalation rate for short-term exposures 	

0.36 m3/hr (daily rate of 8.7 m3/day divided by 24 hours)	

rest:  0.3 m3/hr

sedentary activities:  0.4 m3/hr

light to moderate (i.e., play):  0.7 m3/hr 	

The hourly inhalation rates for children are the values recommended by
EPA Exposure Factors Handbook 1997, pg 5-24, except the light to
moderate rate, which is based on data for play and walking activities
(for children 3-5.9 years based on Adams 1993, pg 5A-3 of EPA 1997,
EFH), and also represents the average of 1 hour light activity and 1
hour of moderate activity for children ages 3-<10 years based on data
from Layton 1993 (i.e., average of 0.5 m3/hr for light activity and 1
m3/hr for moderate activity, pg 5-16 EPA EFH 1997).  These values should
be used to assess short-term scenarios of a few hours in duration, such
as post application inhalation exposures following lawn treatment,
foggers and crack and crevice treatments (depending on chemical-specific
data such as air measurements, vapor pressure, persistence).

	

adult daily inhalation rate	

13.3 m3/day (avg of males and females)	

11.3 m3/day for females

15.2 m3/day for males 

13.3 m3/day for avg of males and females	

Recommended average inhalation rates presented on pg 5-24 of EPA 1997,
Exposure Factors Handbook.  These values should be used to assess
short-term scenarios of a few days  in duration, such as post
application inhalation exposures following crack and crevice treatments,
and termiticide treatments (depending on chemical-specific data such as
air measurements, vapor pressure, persistence). 

	

child daily  inhalation rate	

8.7 m3/day (children 1-6 yrs)	

8.7 m3/day (children 1-12 yr) 

4.5 m3/day (children < 1 yr)	

Recommended average inhalation rates presented on pg 5-24 of EPA 1997,
Exposure factors Handbook.  These values should be used to assess
short-term scenarios of a few days  in duration, such as post
application inhalation exposures following crack and crevice treatments,
and termiticide treatments (depending on chemical-specific data such as
air measurements, vapor pressure, persistence). 



Table 2:  Revised Residential SOPs for Area Treated 

(February 2001)

Equipment or Site	

Turf	

Garden	

Shrubs &

Ornamentals	

Indoor	

Comments/Proposals

	

Area Treated (units are noted below)

	

Belly grinder	

0.5 A (broadcast)

or

1000 ft2 (spot)	

1000 ft2	

1000 ft2	

NA	

Lawn broadcast remains at 0.5 A 

(avg. from PHED is  0.8 A/rep & 1.2 hr/rep).  

This value represents the mean to upper-percentile range of the
distribution of lawn size.  Recent lawn size survey data suggest that up
to 0.5 acre represents 73% of the 2,300 respondents, while nearly 16% of
the respondents had lawn sizes that ranged from 0.57 to 1 acre (Outdoor
Residential Use and Usage Survey and National Gardening Association
Survey 1999).  In this study, 2,300 respondents of 4,100 knew the size
of their lawn.

Garden & shrub/ornamental values reduced from 10000 ft2, supported by
Nat. Home Garden Survey

Push granular spreader	

0.5 acre	

NA	

NA	

NA	

total area treated, not typical for spot treatments, value not modified.

This value represents the mean to upper-percentile range of the
distribution of lawn size (see belly grinder comments).   

Aerosol Can	

1 can

(2 fogger cans)	

1 can

(2 fogger cans)	

1 can

(2 fogger cans)	

3 cans of spray paint, 1 cans for pesticide	

Number cans reduced from 2 to 1 per event.  Supported by PHED (~0.5
hours/can), fogger & spray paint values unchanged

Granular by Hand	

1000 ft2	

1000 ft2	

1000 ft2	

NA	

spot treatments only per SOPs,

value is unchanged

Low Pressure Handwand	

5 gallons

or

1000 ft2 (spot)	

5 gallons

or

1000 ft2 (spot)	

5 gallons

or

1000 ft2 (spot)	

0.5 gallons	

spot treatments on lawns; use gallons basis first but 1000 ft2 can also
be used for turf & gardens, garden & indoor values reduced supported by
PHED and Nat. Home Garden Survey

Backpack	

See Low Pressure Handwand

Not commonly used in indoor assessments (i.e., do not include)

Hose end	

0.5 A (broadcast)

or

1000 ft2 (spot)	

1000 ft2 

or 

100 gallons of finish spray, see siphon rates and other information	

1000 ft2 

or 

100 gallons of finish spray, see siphon rates and other information	

NA	

Broadcast area represents the mean to upper-percentile range of the
distribution of lawn size (see belly grinder comments).  

Based on data from http://www.ortho.com

Output is 2 gallons of finish spray per minute, can siphon from 1 tsp to
8 oz make-up solution per gallon applied, make-up tank capacity is 32
oz, use 4 tanks/event over an hour duration which = 100 gallons of
finish spray when load time is considered, case-by-case labels should be
considered

Airless Sprayer	

NA	

NA	

NA	

15 gallons	

reserved for homeowner use outdoors, values are unchanged

Paintbrush & Roller	

NA	

1 gallon	

1 gallon pesticide	

1 gallon pesticide, 2 gallons paint, 5 gallons deck preservative	

paint is for indoor or outdoors, paint values are unchanged, insecticide
paint-on has been added

Fire Ant	

5 mounds treated (personal communication with Mike Hennessey of BEAD)

If broadcast on whole lawns or spot treatments on lawns, see
bellygrinder

Sprinkler Can	

See Hose-end sprayer for spot treatments only

Pets	

NA	

NA	

NA	

1 pet	

10% for dip, shampoo, dusts and ½ can for RTUs of any formulation if
instructions are ad libitum, values reduced for RTUs

Dusts	

1 container for all uses (e.g., rose dusts) except pets where ½ RTU 

Trigger Pump	

See Aerosol Can

Flea Collar	

NA	

NA	

NA	

1 pet	

value is unchanged

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