Scientific Advisory Panel

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- September 9-10, 1997 SAP Meeting
- SOPS For Residential Exposure Assessments: Pet Treatment

Prior to the development of an exposure assessment for a pet product scenario, the assessor should consult the pesticide label to determine whether the scenario is appropriate based on the pesticide formulation and on the usage characteristics of the product. Specific lableing considerations for pet treatment products are as follows:

**Registered for Use on Pets**: Determine whether the labeling
contains directions for use on pets.

**Limitation and Descriptive Statements**: Look for statements
describing or limiting the use of the pet product. These statements
may be on the front panel of the label associated with the brand
or trade name or in the use-directions section of the labeling.
Assume that a product registered for use on a pet is used at residential
sites unless a specific labeling statement indicates otherwise.
Restricted-Use Pesticide classification and statements such as "For
use by veterinarians or veterinary assistants only" indicate that
the product cannot be **bought or applied** by homeowners. Therefore,
no residential **handler** exposure/risk assessment is required.
Since the treated pets will return to residential sites, a post-application
exposure/risk assessment is required.

**Introduction**

This SOP provides a standard method for estimating potential doses that homeowners may receive during pet treatment from inhalation and dermal contact when chemical specific data are unavailable. This scenario assumes that pesticide exposure occurs while dipping or applying the pesticide to pets. The method to determine handler inhalation and dermal doses from pesticides while treating pets relies on using several assumptions. Thus, this method should be used in the absence of actual field data, or as a supplement to estimates based on field data.

**Methods for Estimating Dose**

Label information is important for selecting appropriate data inputs for the exposure assessment (see Section 9.0). The data required for estimating handler doses from pesticides while treating pets is the application rate. The maximum application rate specified on the label should be used, except in cancer assessments when the typical application rates should be used. However, it should be noted that the typical residential use rate is often the maximum residential use rate. In the absence of actual data, the following assumptions can be used for estimating daily pesticide handler doses.

- Daily dose is based on the amount of active ingredient handled per day (i.e., a single pet treatment event per day). The pesticide label should be used to determine the amount of active ingredient used during each treatment.

- Ten percent ( 0.1) of the active ingredient applied to the pet is assumed to be the amount the homeowner is exposed to during dipping, dusting, and shampooing. This assumption is based on the professional judgement of the OPP staff and assumed to be an upper-percentile value.

- One percent (0.01) of the active ingredient applied to the pet is assumed to be available for dermal and inhalation exposure from handling flea collars. This assumption is based on the professional judgement of the OPP staff and assumed to be an upper-percentile value.

- Adults are assumed to weigh 71.8 kg (use 60 kg for females when the selected endpoint is from a reproductive or developmental study). A body weight of 71.8 kg represents the mean body weight for all adults (i.e., male and female, ages 18 years and older) and is the value recommended in U.S. EPA (1996). A body weight of 60 kg represents the average body weight for females between ages 13 and 54 years (U.S. EPA, 1996). The average body weight for a 10 to 12 year old youth is 39.1 kg. This represents the mean of the median values for males and females at ages 10, 11, and 12 years.

Inhalation and dermal potential dose rates are calculated as follows: PDR = AR * F

where:

PDR = potential dose rate (mg/day)

AR = application rate (i.e., amount of active ingredient handled
during treatment) (mg/day) (assessor needs to determine the amount
of ai in the formulated product)

F = fraction of ai available for exposure (unitless)

Inhalation and dermal potential dose rates, normalized to body
weight, are calculated as follows: PDR_{norm} = PDR /
BW

where:

PDR_{norm} = potential dose rates, normalized to
body weight (mg/kg/day)

BW = body weight (kg)

The body weight used can be adjusted to fit any specific scenario (e.g., exposure to males or females).

**Example Calculations**

The following is an example calculation to determine the combined dermal and inhalation dose from a homeowner spraying a liquid pet treatment pesticide. For the purpose of this example, the application rate is assumed to be 30 mg ai/day.

PDR = AR * F

PDR = 30 mg/day * 0.1

PDR = 3.0 mg/day

Finally, the estimated potential dose rate, normalized to body weight, for an adult with a body weight of 71.8 kg would be:

PDR_{norm} = PDR / BW

PDR_{norm} = (3.0 mg/day) / (71.8 kg)

PDR_{norm} = 0.042 mg/kg/day

**Limitations and Uncertainty**

The uncertainties associated with this assessment stem from assumptions regarding amount of chemical handled and the percentage of which humans are exposed. The estimated doses are believed to be reasonable bounding estimates based on professional judgement.

**References**

U.S. EPA (1996) Exposure Factors Handbook [Draft]. U.S. Environmental Protection Agency, National Center For Environmental Assessment, Washington D.C. EPA/600/P-95/002Ba.

**Introduction**

This SOP provides a standard method for estimating potential doses that homeowners may receive during pet treatment from inhalation and dermal contact when chemical specific data are unavailable. This scenario assumes that pesticide exposure occurs while applying the pesticide to pets using aerosol spray products. The method to determine handler inhalation and dermal dose from pesticides while treating pets relies on using surrogate PHED data. Thus, this method should be used in the absence of actual field data, or as a supplement to estimates based on field data.

**Methods for Estimating Dose**

Label information is important for selecting appropriate data inputs for the exposure assessment (see Section 9.0). The only datum required for estimating handler doses from pesticides while treating pets is the application rate. The maximum application rate specified on the label should be used, except in cancer assessments when the typical application rates should be used. However, it should be noted that the typical residential use rate is often the maximum residential use rate. In the absence of actual data, the following assumptions can be used for estimating daily pesticide handler doses.

- Daily dose is based on the amount of active ingredient handled per day (i.e., a single pet treatment event per day).

- The amount handled during each treatment is assumed to be one-half can of spray (i.e., homeowner may potentially use the entire contents of the product for a single treatment). This is assumed to be a maximum value.

- Unit exposure values from PHED for the application of a typical pesticide product from an aerosol can are similar to that of a pet spray treatment and will be used for this scenario. Dermal and inhalation unit exposures and data confidence descriptions are available in the Appendix B. The current version of PHED uses measures of central tendency to estimate the best-fit unit exposure.

- The density of an organic spray solution contained in a single use pressurized can may be assumed to be 0.80 g/mL unless a product-specific value is available. This is based on a informal survey of various organic solvents described in CRC (1981). A value of 0.80 g/mL represents an mean of various organic solvents from this source.

- Adults are assumed to weigh 71.8 kg (use 60 kg for females when the selected endpoint is from a reproductive or developmental study). A body weight of 71.8 kg represents the mean body weight for all adults (i.e., male and female, ages 18 years and older) and is the value recommended in U.S. EPA (1996). A body weight of 60 kg represents the mean body weight for females between ages 13 and 54 years (U.S. EPA, 1996). The average body weight for a 10 to 12 year old youth is 39.1 kg. This represents the mean of the median values for males and females at ages 10, 11, and 12 years.

The pounds of active ingredient applied for each can of spray can be calculated as follows: AR = V * ρ * (P/100) * CF1

where:

AR = amount of active ingredient applied for each can of
spray (lb ai/can)

V = liquid volume of spray contained in each can (mL/can)

ρ = specific gravity of spray solution contained in can
(g/mL)

P = percent by weight of the pesticide active ingredient in
the spray

CF1 = weight unit conversion factor to convert g units to
lbs (2.2E-3 lb/g)

Inhalation and dermal potential dose rates are calculated as follows: PDR = UE * AR * N

where:

PDR = potential dose rate (mg/day)

UE = unit exposure (mg/lb ai)

N = number of cans spray used per exposure day (cans/day)

Inhalation and dermal potential dose rates, normalized to body
weight, may be calculated as follows: PDR_{norm} = PDR
/ BW

where:

PDR_{norm} = potential dose rate, normalized to
body weight (mg/kg/day)

BW = body weight (kg)

The body weight used can be adjusted to fit any specific scenario (e.g., exposure to adults or children).

**Example Calculations**

The following is an example calculation to determine the dermal dose for a homeowner spraying one-half of a 500 mL can of a 15 percent ai liquid pet treatment pesticide with a specific gravity of 0.8 g/mL, using a unit exposure value of 186.6 mg/lb ai. A complete assessment would include both an inhalation and dermal dose.

The pounds of active ingredient applied for each can of spray can be calculated as follows:

AR = V * ρ * (P/100) * CF1

AR = 500 mL/can * 0.8 g/mL * 15.0%/100 * 2.2E-3 lb/g

AR = 0.13 lb ai/can

Potential dose rate is calculated as:

PDR = UE * AR * N

PDR =186.6 mg/lb ai * 0.13 lb ai/can * 0.5 can/day

PDR = 12.3 mg/day

Finally, the estimated potential dose rate, normalized to body weight, for an adult with a body weight of 71.8 kg would be:

PDR_{norm} = PDR / BW

PDR_{norm} = (12.3 mg/day) / (71.8 kg)

PDR_{norm} = 0.17 mg/kg/day

The dose would be used in conjunction with toxicity data to assess risk.

**Limitations and Uncertainty**

The dose estimates generated using this method are based on upper-percentile assumptions. The uncertainties associated with this assessment stem from the use of surrogate exposure data (e.g., differences in the use scenarios and data confidence) and assumptions regarding the amount of chemical handled. The estimated doses are believed to be reasonable bounding estimates based on professional judgement.

**References**

U.S. EPA (1996) Exposure Factors Handbook [Draft]. U.S. Environmental Protection Agency, National Center For Environmental Assessment, Washington D.C. EPA/600/P-95/002Ba.

CRC (1981) CRC Handbook of Chemistry and Physics, 61st Edition. CRC Press Inc. Boca Raton, Florida.

**Introduction**

This SOP provides a standard method for estimating doses among adults and/or toddlers from dermal contact with pets that have previously been treated with pesticides. This scenario assumes that pesticide residues are transferred to the skin of adults/toddlers that come in contact with treated pets while petting or otherwise touching their pets. The method for estimating postapplication dermal dose from pesticides on pets is based on assumptions. Thus, this method should be used in the absence of actual field data.

**Methods for Estimating Dose**

Label information is important for selecting appropriate data inputs for the exposure assessment (see Section 9.0). The data required for estimating postapplication doses from pesticide residues on pets is the application rate. The maximum application rate specified on the label should be used. In absence of actual data, the following assumptions are also needed for estimating daily pesticide postapplication doses.

- On the day of application it may be assumed that 20 percent (0.20) of the application rate is retained on the pets as dislodgeable residue. This value is based on the professional judgement and experience of the OPP staff from the review of company-submitted data and is believed to be an upper-percentile assumption.

- Ten percent ( 0.10) of the available residues are transferred to the homeowner during contact with the treated animals. This assumption is based on the professional judgement of the OPP staff and assumed to be an upper-percentile value.

- Postapplication
activities must be assessed on the same day that the pesticide is
applied since it is assumed that individuals could handle/touch
their pets immediately after application. For subsequent days after
application, it may be assumed that residues do **not** dissipate
because it is frequently desirable to maintain a specific level
of pesticide on the pet (i.e., flea collars).

- It is assumed that one animal is contacted.

- Adults are assumed to weigh 71.8 kg (use 60 kg for females when the selected endpoint is from a reproductive or developmental study). A body weight of 71.8 kg represents the mean body weight for all adults (i.e., male and female, ages 18 years and older) and is the value recommended in U.S. EPA (1996). A body weight of 60 kg represents the mean body weight for females between ages 13 and 54 years (U.S. EPA, 1996). Toddlers (3 years old), used to represent the 1 to 6 year old age group, are assumed to weigh 15 kg. This is the mean of the median values for male and female toddlers. (U.S. EPA, 1996).

Dermal potential dose rates for liquids are calculated as follows: PDR = AR * F * T

where:

PDR = potential dose rate (mg/day)

AR = amount of active ingredient applied per day (assessor
needs to determine the amount of ai in the formulated product)

F = fraction of ai available on pet

T = fraction of residue transferred to the skin

Dermal potential dose rates, normalized to body weight, are calculated
as: PDR_{norm} = PDR / BW

where:

PDR_{norm} = potential dose rate, normalized to
body weight (mg/kg/day)

BW = body weight (kg)

The body weight used can be adjusted to fit any specific scenario (e.g., exposure to adults or toddlers).

**Example Calculations**

The following is an example calculation to determine the dose. For the purpose of this example, the application rate is assumed to be 30 mg ai/day. Thus, the dose on day 0 is as follows:

PDR = AR * F * T

PDR = 30 mg/day * 0.2 * 0.1

PDR = 0.6 mg/day

Finally, the estimated potential dose rate, normalized to body weight, for an adult with a body weight of 71.8 kg would be:

PDR_{norm} = PDR / BW

PDR_{norm} = (0.6 mg/day) / (71.8 kg)

PDR_{norm} = 8.36E-3 mg/kg/day

The dose would be used in conjunction with toxicity data to assess risk.

**Limitations and Uncertainty**

The uncertainties associated with this assessment stem from the use of an assumed amount of pesticide retained on pets, and assumptions regarding transfer of chemical residues. The estimated doses are believed to be reasonable high-end estimates based on professional judgement.

**References**

U.S. EPA (1996) Exposure Factors Handbook [Draft]. U.S. Environmental Protection Agency, National Center For Environmental Assessment, Washington D.C. EPA/600/P-95/002Ba.

**Introduction**

This SOP provides a standard method for estimating dose among toddlers from incidental ingestion of pesticide residues from previously treated pets. This scenario assumes that pesticide residues are transferred to the skin of toddlers from the handling/touching of treated pets and are subsequently ingested as a result of hand-to-mouth transfer. The method for estimating postapplication incidental ingestion dose from pesticide residues on pets is based on assumptions when adequate chemical specific field data are unavailable.

**Methods for Estimating Potential Dose**

Label information is important for selecting appropriate data inputs for the exposure assessment (see Section 9.0). The only datum required for estimating postapplication doses to pesticide residues on pets is the application rate (e.g., mg ai per treatment). The maximum application rate specified on the label should be used, except in cancer assessments when the typical application rates should be used. It should be noted, however, that the typical residential use rate is often the same as the maximum rate. The following assumptions are also needed for estimating pesticide postapplication doses.

- On the day of application, it may be assumed that 20 percent (i.e., 0.20) of the application rate is available on the pets as dislodgeable residue. This value is based on the professional judgement and experience of the OPP staff from the review of company-submitted data and is believed to be an upper-percentile assumption.

- Postapplication activities must be assessed on the same day that the pesticide is applied since it is assumed that toddlers could handle/touch pets immediately after application. For subsequent days after application, it may be assumed that the pesticide will not dissipate because it is frequently desirable to maintain a specific level of pesticide on the pet (i.e., flea collars).

- The
median surface area of both hands is 350 cm^{2} for a toddler
(age 3 years). This value represents the average of the 50th percentile
total surface area values for males and females in the 2<3 year
and 3<4 year age groups, multiplied by the average percentage
of the total body represented by hands for males and females. (U.S.
EPA, 1996a).

- Replenishment of the hands with pesticide residues is assumed to be an implicit factor in this assessment.
- An average pet is assumed to have a body surface area of approximately
6,000 cm
^{2}. This is based on an assumed body weight of a medium size dog of 30 lbs and the following algorithm for estimating surface area for mammals from a known body weight, as presented in EPA's Wildlife Exposure Factors Handbook (U.S. EPA, 1993): Surface Area (cm^{2}) = 12.3 Body Weight^{0.65}(g). - It is assumed that there is a one-to-one relationship between
the dislodgeable residue on the surface of the pet and on the
surface area of the skin after contact (i.e., if the dislodgeable
residue on the pet is 1 mg/cm
^{2}, then the residue on the human skin is also 1 mg/cm^{2}after contacting the pet).

- The duration of exposure for toddlers is assumed to be 2 hours per day. This is based on the professional judgement and experience of the OPP staff. This time frame (2 hours) is approximately the same time children play outside per day. This is assumed to be an upper-percentile value

- Toddlers (age 3 years), used to represent the 1 to 6 year old age group, are assumed to weigh 15 kg. This is the mean of the median values for male and female children (U.S.EPA, 1996a).

Potential dose rates from ingestion are calculated as follows: PDR = DR * SA * FQ * ET

where:

PDR = potential dose rate (mg/day)

DR = dislodgeable residue on pet (mg/cm^{2} pet)

SA = surface area of the hands (cm^{2}/event)

FQ = frequency of hand-to-mouth activity (events/hr)

ET = exposure time (hr/day)

and DFR = (AR * F) / SA_{pet}

where:

AR = application rate (mg ai)

F = fraction of ai available on pet (unitless)

SA_{pet} = surface area of the pet (cm^{2})

Potential dose rates, normalized to body weight, are calculated
as: PDR_{norm} = PDR / BW

where:

PDR_{norm} = potential dose rate normalized to body
weight on day "t" (mg/kg/day)

BW = body weight (kg)

**Example Calculations**

The following is an example calculation to determine the dose based on an assumed dislodgeable residue. For the purpose of this example, the application rate is assumed to be 30 mg/day. Thus, the dislodgeable residue on the pet is as follows:

DR = AR * F

DR = (30 mg * 0.2) / 6,000 cm^{2}

DR = 0.001 mg/day

The estimated incidental ingestion dose for a toddler on the day of application would be as follows:

PDR = DR * SA * FQ * ET

PDR = 0.001 mg/cm^{2} * 350 cm^{2}/event *
1.56 events/hr * 2 hr/day

PDR = 1.1 mg/day

Finally, the estimated potential dose rate, normalized by body weight, for a toddler with a body weight of 15 kg would be:

PDR_{norm} = PDR / BW

PDR_{norm} = (1.1 mg/day) / (15 kg)

PDR_{norm} = 0.07 mg/kg/day

**Limitations and Uncertainty**

The dose estimates generated using this method are based on some upper-percentile and some central tendency assumptions and are considered to be representative of high-end exposures. The uncertainties associated with this assessment stem from the use of an assumed amount of pesticide available from the treated pests, and assumptions regarding dissipation and hand-to-mouth activity. The estimated doses are believed to be reasonable high-end estimates based on observations from chemical-specific field studies and professional judgement.

**References**

U.S. EPA (1993) Wildlife Exposure Factors Handbook. U.S. Environmental Protection Agency, Office of Research and Development, Washington, DC. EPA/600/R-93/187a.

U.S. EPA (1996a) Exposure Factors Handbook. [Draft]. U.S. Environmental Protection Agency, National Center for Environmental Assessment, Washington, DC. EPA/600/P-95/002Ba.

U.S. EPA (1996b) Time location activity pattern methodology: the creation of Bayesian distributions for the field investigations of exposure of infants and children to toxic substances. EPA-007-2. (To be included in an EPA Project Report entitled "Protocol for dermal exposure assessment in residential and non-occupational environments" which is currently in preparation and subject to EPA/ORD peer review).