### January 18, 2011

Docket ID No. EPA-HQ-OPP-2007-0935



## SUPPLEMENT TO

NATURAL RESOURCES DEFENSE COUNCIL’S

PETITION TO CANCEL PET COLLAR USES

FOR THE PESTICIDE PROPOXUR

On November 26, 2007, the Natural Resources Defe nse Council (NRDC) filed a petition to the

U.S. Environmental Protection Agency (EPA) to, among other things, cancel all pet collar uses

for the pesticide propoxur because of the unnece ssary dangers posed by exposure to this toxic

chemical, particularly in light of the alternatives available. To date, EPA has not responded. In

April, 2009, NRDC supplemented its petition to EP A with its report “Poison on Pets II” showing

unacceptably high residues from touching pets w earing propoxur-impregnated flea collars. This

document incorporates the arguments from the orig inal petition, the supple ment to the original

petition, and provides additional evidence of elevat ed risks to children from propoxur formulated

pet collars.

Since the filing of the two previous petitions , EPA has initiated a Registration Review for

propoxur. As part of this review, new documents detailing exposure and risk information for pet

collar uses of propoxur have been posted to the docket. These include a residential exposure and

risk assessment for propoxur-formulated pet collars performed by EPA, and information

provided by Sergeant’s Pet Care Products (one of the manufacturers of propoxur-formulated pet

collars and EPA registrant) contesting the agency assessment and providing their own

assessment. 1 2 3 

### Our analysis of the EPA documents and those provided by the manufacturer

demonstrates evidence of an elevated risk to children from use of propoxur formulated pet

collars.

EPA’s assessment of children’s exposure to propoxur-formulated pet collars found unacceptably

high risks. However, EPA’s assessment si gnificantly underestimates risks from propoxurformulated collars by failing to assess dermal e xposures, using inadequate estimates of children’s

hand-to mouth behavior, and ignor ing cancer risks. Furthermore, using the alternative residue

levels submitted to EPA by Sergeant’s to calculate the risk also identifies elevated risks to

children.

1 EPA Memorandum dated April 7, 2010 Subject: Propoxur: Occupational and Residential Exposure and Risk

Assessment for Propoxur Formulated Pet Collars Docket Number: EPA-HQ-OPP-2009-0806

2 EPA Memorandum dated July 12, 2010 Subject: Issues for Consideration Related to Propoxur: Occupational and

Residential Exposure and Risk Assessm ent for Propoxur Formulated Pet Co llars Docket Number: EPA-HQ-OPP2009-0806

3 Johnston, Jason E. 2010. Residential Risk Assessment fo r Post-application Exposures Associated with Pet Collars

Containing Propoxur Using Rate of Release Data from Historical On-Animal Studies Docket Number: EPA-HQOPP-2009-0806Supp. to NRDC petition to cancel pet collar uses for propoxur

Docket ID No. EPA-HQ-OPP-2007-0935 2



### All the evidence before the Agency provides EP A with ample reason to cancel pet uses for

propoxur. EPA should immediatel y take action on their own assessment and the evidence

presented here to protect child ren from these dangerous produc ts and cancel pet uses of

propoxur.

EPA’s Assessment of Children’s Exposure to Propoxur Formulated Pet Collars Found

Unacceptable Risks.

In a memorandum dated April 7, 2010, EPA detailed the results of its most recent occupational

and residential exposure and risk asse ssment for propoxur formulated pet collars. 4 

### This

assessment found Margins of Exposure (MOEs) 5 

### ranging from 20 to 62 for child incidental oral

ingestion risk. These values are significantly le ss than the Agency’s threshold for safety of 1000

and the document concluded that the “r isks are of concern to the Agency”. 6 

### The calculations in

this assessment were refined in a follow -up memorandum, dated July 12, 2010, and the new

MOEs ranged from 55 to 82. 7 

### Together the calculations presented in these two memos are

hereinafter referred to as the “2010 risk assessment”. (See Table 1 for exposure parameters and

Appendix A for relevant exposure algorithm and calculation method).

4 EPA Memorandum dated April 7, 2010 Subject: Propoxur: Occupational and Residential Exposure and Risk

Assessment for Propoxur Formulated Pet Collars Docket Number: EPA-HQ-OPP-2009-0806

5 The Margin of Exposure (MOE) is the ratio of the estim ated dose to the level of safe exposure. The lower the

MOE the higher the risk.

6 EPA Memorandum dated April 7, 2010 Subject: Propoxur: Occupational and Residential Exposure and Risk

Assessment for Propoxur Formulated Pet Collars Docket Number: EPA-HQ-OPP-2009-0806

7 EPA Memorandum dated July 12, 2010 Subject: Issues for Consideration Related to Propoxur: Occupational and

Residential Exposure and Risk Assessm ent for Propoxur Formulated Pet Co llars Docket Number: EPA-HQ-OPP2009-0806Supp. to NRDC petition to cancel pet collar uses for propoxur

Docket ID No. EPA-HQ-OPP-2007-0935 3

Table 1: Residential post application for only hand

‐ to

‐ mouth exposures using EPA (2010) transferable

residue calculations and unrealistic exposure assumptions from EPA’s (2010) residential exposure and

risk assessment.

Variable Source Wellmark

Dog Collar Wellmark

Cat Collar Sergeant’s

Dog Collar Sergeant’s

Cat Collar

Weight of the collar (g)

EPA (2010)

Residential

Exposure and

Risk Assessment

for Propoxur

Formulated Pet

Collars 34 10.5 30 14

AR* (Wellmark 10%

‐ Sergeant’s 9%) (g) 3.4 1.05 2.7 1.26

F(AR) 0.2 0.2 0.2 0.2

SA(pet) (cm2) 5986 2737 5986 2737

SAL 0.5 0.5 0.5 0.5

SA(hands) (cm2) 20 20 20 20

Freq (events/day) 1 1 1 1

BW (kg) 15 15 15 15

Daily Transferable

residue (mg/cm2

‐ day) 0.008 0.005 0.006 0.006

Dose (mg/kg)

‐

ingestion 0.005 0.003 0.004 0.004

NOAEL (mg/kg

‐ day) 0.28 0.28 0.28 0.28

MOE 55 82 70 68

* See Appendix A for abbreviations and calculation algorithms.



### Although these refined MOEs are hi gher, they are still well belo w 1000 and thus still represent

an inadequate margin of safety. Due to the un acceptable risks determined in this assessment,

EPA should immediately cancel pet uses of the pesticide propoxur.

EPA’s Residential Exposure and Risk Assessme nt Significantly Underestimates Health

Risks From Propoxur In Pet Collars.

The most recent risk assessment conducted by EPA continues to be flawed, as has EPA’s past

risk assessments for propoxur. In the 2010 risk assessment, EPA failed to consider the risks

from dermal exposure to propoxur in pet collars. Furthermore, as NRDC has mentioned time

and again, EPA makes faulty assumptions about toddlers. 8 

### Specifically, EPA either makes

unrealistic assumptions about, or completely igno res aspects of, toddlers’ mouthing behavior.

And finally, EPA completely ignor es the cancer risk associated with this pesticide. These

deficiencies in the risk assessment make a pestic ide that EPA has already identified as of concern

even more problematic.

8 NRDC comments on the EPA Organophosphate Cumulative Risk Assessment (October 2, 2006) EPA docket EPAHQ-OPP-2006-0618. Supplement to Natural Resources Defense Council Petition To Cancel Pet Collar Uses For

The Pesticide Propoxur (April 23, 2009) EPA docket EPA-HQ-OPP-2009-0207-0003.Supp. to NRDC petition to cancel pet collar uses for propoxur

Docket ID No. EPA-HQ-OPP-2007-0935 4



### Failure to Assess Dermal Exposures

EPA’s 2010 residential risk assessment of exposur e to propoxur-formulated flea collars ignored

the risks associated with absorbing propoxur thro ugh the skin. EPA incorrectly claims in the

occupational and residential risk assessment that there are no data on rates of dermal absorption

for propoxur. 9 

### However, the 1997 Reregistration Eligib ility Determination for propoxur cites a

human study that found a 20% dermal absorption rate. 10 

### Normal activity with a pet, including

petting and hugging, would be expected to result in dermal contact ranging from the surface of

the hands to a significantly larger skin surface area. This exposure pattern was included in the

risk assessment performed for pet uses of th e pesticide dichlorvos (DDVP), in which EPA

calculated dermal exposures based on one pet hug per day. Given this evidence, risk assessments

for pet uses of propoxur must includ e calculation of dermal exposure.

Adjusting EPA’s risk calculation from the reside ntial exposure assessment to include the dermal

exposure resulting from one pet hug per day results in an estimated dose for dog and cat collars

ranging from 0.194 to 0.158 mg/kg-day and MOEs of 1 or 2. This represents up to a 40 fold

increase in the risk compared to EPA’s 2010 risk assessment. (See Table 2 for exposure

parameters and Appendix A for relevant exposure algorithm and calculation method).

9 EPA Memorandum dated April 7, 2010 Subject: Propoxur: Occupational and Residential Exposure and Risk

Assessment for Propoxur Formulated Pet Collars Docket Number: EPA-HQ-OPP-2009-0806

10 US EPA 1997. Reregistration Eligibility Decisi on (RED) Propoxur. EPA-738-R-97-009. page 20.Supp. to NRDC petition to cancel pet collar uses for propoxur

Docket ID No. EPA-HQ-OPP-2007-0935 5

Table 2: Residential post application for hand

‐ to ‐ mouth and dermal exposures using EPA (2010)

transferable residue calculations and keeping EPA (2010) unrealistic exposure assumptions for hand

‐ to

‐

mouth and adding a conservative estimate of dermal exposures following EPA guidance.

Variable Source Wellmark

Dog Collar Wellmark

Cat Collar Sergeant’s

Dog Collar Sergeant’s

Cat Collar

Weight of the collar (g)

EPA (2010)

Residential

Exposure and

Risk Assessment

for Propoxur

Formulated Pet

Collars 34 10.5 30 14

AR (Wellmark 10%

‐ Sergeant’s 9%) (g) 3.4 1.05 2.7 1.26

F(AR) 0.2 0.2 0.2 0.2

SA(pet) (cm2) 5986 2737 5986 2737

SAL 0.5 0.5 0.5 0.5

SA(hands) (cm2) 20 20 20 20

Freq (events/day) 1 1 1 1

BW (kg) 15 15 15 15

SA(hug) 1875 1875 1875 1875

Freq (events/day) 1 hug per day

scenario 1 1 1 1

Fraction absorbed EPA (1997)

Propoxur RED 0.2 0.2 0.2 0.2

Daily transferable

residue (mg/cm2

‐ day) 0.008 0.005 0.006 0.006

Dose (mg/kg

‐ day)

‐

ingestion 0.005 0.003 0.004 0.004

Dose (mg/kg

‐ day)

‐

dermal 0.189 0.128 0.150 0.153

Total Dose (mg/kg

‐ day) 0.194 0.131 0.154 0.158

NOAEL (mg/kg

‐ day) 0.28 0.28 0.28 0.28

MOE 1 2 2 2



### Underestimation of Children’s Hand-to-Mouth Behavior

In the 2010 residential risk assessment, EPA assu med that a child would have only one hand-tomouth event per day after exposure to a treated pet. This assumption is not substantiated by

either the available literature or by EPA’s own previous risk assessments for pet products. A

meta-analysis performed by Xue et al. (2007) re ported a mean hand-to-mouth activity for 1-2

year olds of 19.6 events per hour. 11 

### Residential post-app lication exposure to pesticides in flea

collars in the Organophosphate Cumulative Risk Assessment (2006) uses a “most likely” value

of nine events per hour. 12 

### EPA’s assessment of DDVP, whic h had been used in pet collars,

11 Xue, J., Zaratarian,V., Moya,J., Freeman, N., Beamer, P., Black, K., Tulve, N., and Shalat,S. 2007 “ A MetaAnalysis of Children’s Hand-to-Mouth Frequency Data for Estimating Nondietary Ingestion Exposure.” Risk

Analysis , 27:2

12 EPA. 2006. Organophosphate Cumulative Risk AssessmentSupp. to NRDC petition to cancel pet collar uses for propoxur

Docket ID No. EPA-HQ-OPP-2007-0935 6



### assumed that toddlers were exposed for 2 hours per day. 13 

### The assumptions in the 2010 propoxur

risk assessment are unrealistic, inconsistent w ith previous agency findings, and significantly

underestimate actual ri sk to toddlers.

The effect of this low assumption for hand-to -mouth events in the 2010 propoxur risk assessment

is that EPA significantly underest imates the potential dose to a child from exposure to a pet

collar. This is illustrated by adjusting EPA’s risk calculation from th e residential exposure

assessment to use more reasonable hand-to-mouth variable exposure parameters from other EPA

risk assessments. For example, using EPA’s “most likely” assumption of nine hand-to-mouth

events from the OP Cumulative Risk Assessm ent and the two hours per day exposure from the

DDVP risk assessment, would result in dose es timates ranging from 0.061 to 0.091 mg/kg - day

for dog and cat collars and co rresponding MOEs from 3 to 5. (See Table 3 for exposure

parameters and Appendix A for relevant expos ure algorithm and calculation method.) This

represents up to a 20 fold increase in th e dose compared to EPA’s 2010 risk assessment.

Table 3: Residential post application for only hand

‐ to ‐ mouth exposures using EPA (2010) transferable

residue calculations and more realistic hand

‐ to

‐ mouth exposure parameters from other EPA risk

assessments for pet collars.

Variable Source Wellmark

Dog Collar Wellmark

Cat Collar Sergeant’s

Dog Collar Sergeant’s

Cat Collar

Weight of the collar (g)

EPA (2010)

Residential

Exposure and Risk

Assessment for

Propoxur

Formulated Pet

Collars 34 10.5 30 14

AR (Wellmark 10%

‐ Sergeant’s 9%) (g) 3.4 1.05 2.7 1.26

F(AR) 0.2 0.2 0.2 0.2

SA(pet) (cm2) 5986 2737 5986 2737

SAL 0.5 0.5 0.5 0.5

SA(hands) (cm2) 20 20 20 20

BW (kg) 15 15 15 15

Mouthing events

(events/hr) EPA (2006) CRA for

Organophosphates 9 9 9 9

Duration of exposure

(hrs/day) EPA (2006) RED

DDVP 2 2 2 2

Freq (events/day)

=

events/hour * hours/day = events/hour *

hours/day 18 18 18 18

Daily transferable

residue (mg/cm2

‐ day) 0.008 0.005 0.006 0.006

Dose (mg/kg

‐ day)

‐

ingestion 0.091 0.061 0.072 0.074

NOAEL (mg/kg

‐ day) 0.28 0.28 0.28 0.28

MOE 3 5 4 4

13 EPA (2006) Reregistration Eligibility Determina tion for Dichlorovos (DDVP) EPA-738-R-06-013Supp. to NRDC petition to cancel pet collar uses for propoxur

Docket ID No. EPA-HQ-OPP-2007-0935 7



### The exposure calculation in Table 3 assumes that a toddler’s hand is e qually replenished with

pesticide residue after each mouthing event. Wellmark International contends that this

assumption is incorrect. Specifically, in comm ents submitted to EPA in opposition to NRDC’s

petition to cancel pet uses of propoxur, Wellmark claimed that a child’s hands would not be

replenished with the same residue level each time because pesticid e residues would be

concentrated near the collar and, once remove d due to petting activity, would not be replaced

right away. Wellmark also claimed that it would be unrealistic to assume that a child would fully

replenish their fingers multiple times an hour. 14 

### However, as explained below, there is sufficient

evidence to support retaining this assumpti on when assessing exposures from propoxur

formulated pet collars.

A child actively playing with a pet is in regu lar contact with the pet’s fur. The EPA risk

calculation assumes that the palmar surf ace of three fingers, equivalent to 20 cm 2 

### of finger

surface area, are inserted in the mouth per mout hing event. However, regular petting behavior

involves contact of the whole hand with the fur and pesticide residues, meaning a larger area

than just three fingers would pick up residue during each petting event. If each petting event

transfers pesticide residue to the palmar surf ace of both hands of a child this equals 66.7 cm 2 

### of

contaminated finger surface area and 176 cm 2 

### of the total hand surface area. 15 16 

### Therefore, the

exposure scenario of nine mouthing events per hour consisting of an equal, and maximal, level of

residue, from other EPA risk assessments for pet products, can be achie ved a number of ways.

This includes nine separate petti ng and mouthing events or, if the child were to mouth different

fingers during each event, both hands would only n eed to be replenished (through petting) about

three times (every 20 minutes). 17 

### If the child were to mouth th e palmar surface of the fingers and

the palm following a petting event, the same leve l of exposure would be ac hieved after just one

hand replenishment per hour. 18 

### Therefore, this exposure scenar io can be understood to represent

a range from one to nine petting events per hou r (or every 7 to 60 minutes) where the hands are

replenished with pesticide residu e, which is not inconsistent with normal child/pet interactions.

Furthermore, Wellmark’s concern that there woul d be insufficient residue on the pet’s fur to

support this exposure scenario is without merit. EPA’s exposure scenario of nine mouthing

events consisting of the palmar surface of three fingers equals contact with 180 cm 2 

### of residue

contaminated fur per hour, or 3% of th e surface area of the default sized dog. 19 

### On a treated pet

there is likely to be at least th is amount of fur with the maxima l pesticide residue available for a

child to fully replenish his or he r hands. Therefore, the same leve l of residue would be available

for potential ingestion for each mouthing event a nd this assumption should be conserved in the

risk assessment.

14 Wellmark International. 2009. Comments Submitted in Response to: Petition Requesting Cancellation of

Propoxur Pet Collar Uses; Notice of Availability. April 9, 2009. FR 74 (66): 15980-15981. Docket ID No.: EPAHQ-Opp-2009-0207.

15 (20cm 2 /3 fingers) * 10 fingers = 66.7 cm 2

. 16 Palmar surface of both hands is assumed to equal ha lf the total surface area of a child’s hands (350cm 2 /2 = 176

cm 2 ). EPA.1997. Standard Operating Procedure for Residential Exposure Assessment.

17 Nine mouthing events *20 cm 2 = 180cm 2 of mouthed area per hour. 180 cm 2 /66.7 cm2 per petting event = 2.69 or

3 petting events per hour.

18 180 cm 2 /176 cm 2 per petting event = 1.02 or 1 petting event per hour.

19 180 cm 2 per hour /5986 cm 2 per dog = 3% per hour for contact with one dog.Supp. to NRDC petition to cancel pet collar uses for propoxur

Docket ID No. EPA-HQ-OPP-2007-0935 8



### EPA also ignored “indirect” hand-to-mouth activ ity, which is the exposure from toddlers who

touch an object or food with pest icide-contaminated hands and then put that object or food into

their mouths. However, published studies show that there is actually noticeable indirect hand to

mouth activity in infants and child ren. In fact, one study found that, on average, a toddler will

touch an object and then put that object into his or her mouth 15 times in one hour. At the high

end of the study’s distribution (90th percentil e), that rate rises to 66 times per hour. 20 

### This same

study found a statistically significant positive correl ation between the frequency of object or food

in mouth activity and blood lead levels.

Taken together, this evidence demonstrates that the risk to children from pet collar uses is

substantially greater th an EPA calculated in its 2010 risk assessment due to significant

underestimates in hand-to-mouth exposures stemmi ng from inadequate assumptions of hand-to

mouth frequency and failur e to include indirect hand-to-mouth exposures.

In total, when a conservative estimate of dermal exposure is added to the more realistic estimates

of children’s hand-to-mouth exposures used in previous EPA risk assessments, the estimated

dose is about 56 times greater than what is described in EPA’s 2010 risk assessment. 21 

### These

calculations demonstrate the degree to which the exposure calculations used in the 2010 risk

assessment are inadequate and result in a signif icant underestimate of risks to children from

propoxur formulated pet collars.

Failure to Consider Cancer Risks

Propoxur is classified as a Group B2 Probable Human Carcinogen with a unit risk Q 1 

### * of 3.7 x

10 -3



### . 22 

### It is also listed as a chemical known to the state of California to cause cancer under

California’s Safe Drinking Wate r and Toxic Enforcement Act. 23 

### As of December 2010, all

propoxur-formulated flea collars sold in Californi a carry the required wa rning label indicating

that propoxur is a known carcinogen. Despite this evidence of propoxur’s carcinogenicity, EPA

failed to include a cancer risk assessment in the 2010 risk assessment based on the stated

explanation that the cancer determination was ba sed on exposures “orders of magnitude greater

than what is currently allowable for propoxur”. 24 

### However, as explained below, EPA’s

justification is both insu fficient and inaccurate.

Taking into account the revised hand-to-mouth frequency and dermal exposure adjustments to

the dose calculation used above for children’s e xposures, and assuming adu lt exposure is limited

to dermal exposure from one pet hug per da y, the lifetime cancer risk is around 5.01 x 10 -4 

### or

20 Ko,S., Schaefer, P.D., Vicario, C.M., and Binns, H.J. 2007.“Relationship of Video Assessments of Touching and

Mouthing Behaviors During Outdoor Play in Urban Residential Yards to Parental Perceptions of Child Behaviors

and Blood Lead Levels.” Journal of Exposure Science and Environmental Epidemiology.

21 Sum of dermal dose plus revised hand to mouth for Wellmark Dog collar (0.189 mg/kg-day + 0.091mg/kg-day =

0.28 mg/kg-day). Revised dose compared to EPA estimate from 2010 risk assessment = 0.28/0.005 = 56.

22 US EPA 1997. Reregistration Eligibility Decision (RED) Propoxur. EPA-738-R-97-009

23 California Health and Safety Code Section 25249.6 (commonly referred to as “Proposition 65.”

24 EPA Memorandum dated April 7, 2010 Subject: Propoxur: Occupational and Residential Exposure and Risk

Assessment for Propoxur Formulated Pet Collars Docket Number: EPA-HQ-OPP-2009-0806Supp. to NRDC petition to cancel pet collar uses for propoxur

Docket ID No. EPA-HQ-OPP-2007-0935 9



### about 500 per million exposed. 25 

### (See Appendix B for calculati on) This cancer risk exceeds

EPA’s acceptable risk range of 1 to 100 per million exposed. 26 

### In addition, it is likely an

underestimate because it does not account for incr eased early life suscepti bility, adult hand-tomouth exposures, and relies on low-end estimate s of dermal exposures. This calculation

demonstrates that there is a significant cancer risk associated with exposures from propoxur

formulated pet collars that shoul d be included as part of the residential exposure assessment.

Even the Registrant’s Transferable Residue Calc ulations Result in Un acceptable Risks to

Children.

In study dated June 22, 2010, registrant Sergeant’s Pet Care Products claimed that the EPA 2010

risk assessment overestimated the levels of pes ticide residue to be expected 15 days following

application of the pet collar. Instead, Sergeant’s proposed two alternate mechanisms for

calculating the amount of pesticide residue likely to be transferred to the ha nd of a child and then

calculated the dose and MOE asso ciated with those adjusted residues using EPA’s 2010 risk

assessment assumptions.

Based on Sergeant’s first adjustment to the rate of propoxur released from the collar, the dose

calculated using EPA’s exposure assessmen t assumption for a medium dog was 0.000770

mg/kg-day with a MOE of 466, which is less than EPA’s safety margin (MOE of 1000) and

therefore represents an unaccepta ble risk. Sergeant’s made an additional adjustment to the

amount of residue expected to transfer to a child’s hand. Based on that second adjustment,

Sergeant’s calculated the dose to be 0.0000932 mg/kg-day and the MOE to be 3,000.

However, as we discussed above, EPA’s assessm ent (and by extension, Sergeant’s calculations)

uses unrealistically low estimates of hand-to -mouth activity and fails to include dermal

exposures. A calculation using a more comprehens ive exposure assessment (as in the examples

given above) and using both of Sergeant’s adjustme nts for the residue that would be transferred

onto a child’s hand, results in dose estimates ranging from 0.005 to 0.007 mg/kg-day and MOEs

between 42 and 54 for Sergeant’s products. (S ee Figure 4, for exposure parameters and

Appendix A for relevant exposure algorithm and calculation method.) These MOEs are far less

than EPA’s safety margin (MOE of 1000) and represent an unacceptable risk to children.

25 As per EPA guidance, children’s exposure pattern was us ed up to age 5. Cancer risk was calculated as the

weighted average exposure over a 70 year lifetime.Supp. to NRDC petition to cancel pet collar uses for propoxur

Docket ID No. EPA-HQ-OPP-2007-0935 10

Figure 4: Residential post application for hand

‐ to ‐ mouth and dermal exposures using Sergeant’s

transferable residue calculations and exposure parameters from EPA risk assessments for other pet

collars.

Variable Source Sergeant’s

Dog Collar

(medium) Sergeant’s

Dog Collar

(large) Sergeant’s

Cat Collar

Weight of the collar (g)

Sergeant’s 2010

Comments

submitted to EPA 25 32 14

AR

‐ Total ( 9%) (g) 2.25 2.88 1.26

AR

‐ 15 days (18%) (g) 0.405 0.5184 0.2268

F(AR)

‐ adjusted 0.031 0.031 0.031

SA(pet) (cm2) EPA (2010)

Residential

Exposure and Risk

Assessment for

Propoxur

Formulated Pet

Collars 5986 5986 2737

SAL 0.5 0.5 0.5

SA(hands) (cm2) 20 20 20

BW (kg) 15 15 15

SA(hug) 1875 1875 1875

Mouthing events (events/hr) EPA (2006) CRA for

Organophosphates 9 9 9

Duration of exposure

(hrs/day) EPA (2006) RED

DDVP 2 2 2

Freq (mouthing events/day) = events/hour *

hours/day 18 18 18

Freq (events/day) 1 hug per day

scenario 1 1 1

Fraction absorbed EPA (1997)

Propoxur RED 0.2 0.2 0.2

Daily transferable residue

(mg/cm2

‐ day) 0.0001 0.0002 0.0002

Dose (mg/kg

‐ day)

‐ ingestion 0.002 0.002 0.002

Dose (mg/kg

‐ day)

‐ dermal 0.003 0.004 0.004

Total Dose (mg/kg

‐ day) 0.005 0.007 0.006

NOAEL (mg/kg

‐ day) 0.28 0.28 0.28

MOE 54 42 44Supp. to NRDC petition to cancel pet collar uses for propoxur

Docket ID No. EPA-HQ-OPP-2007-0935 11



### Conclusion

Taken together, the evidence prov ided here and in previous NR DC submissions demonstrates

children can be exposed to leve ls of propoxur that si gnificantly exceed the reference dose.

Therefore, EPA must exercise it s statutory obligation to protect children by cancelling all pet

collar uses of propoxur.

Respectfully submitted,

Miriam Rotkin-Ellman, MPH

Gina Solomon, MD, MPH

Mae Wu, Esq.

Natural Resources Defense CouncilSupp. to NRDC petition to cancel pet collar uses for propoxur

Docket ID No. EPA-HQ-OPP-2007-0935 12

APPENDIX A: Exposure Assessments Algorithms

Abbreviations

TR = Transferable Residue

SAL = Saliva Extraction Factor

SA hands = Hand Surface Area

SA pet = Pet Surface Area

SA hug = Child’s Hug Surface Area

Freq = Frequency of Events

BW = Body Weight

AR = Application Rate

F AR = Fraction available on pet’s body

MOE = Margin of Exposure

Residential Post

‐ application incidental oral ingestion (hand

‐ to

‐ mouth)

Dose (mg/kg

‐ day)

= (Transferable residue (TR) * Saliva extraction factor (SAL) * Hand surface area

(SA hands ) *Frequency of events (Freq))/Body Weight (BW)

Transferable residue (mg/cm 2 )

= (Application Rate (AR) *Fraction available on pet’s body (F

AR ))/Surface

Area of pet (SA pet )

Daily transferable residue (mg/cm 2

‐ day)

= TR/15 days

MOE = No Observed Adverse Effect Level/Dose

Source: US EPA (2010). Propoxur: Occupational and Residential Exposure and Risk Assessment for

Propoxur Formulated Pet Collars

Residential Post

‐ application dermal exposures

Dose (mg/kg

‐ day)

= (Transferable residue (TR) * Dermal absorption factor * Surface area of child hug

(SA hug ) *Frequency of events (Freq))/Body Weight (BW)

Total Dose (mg/kg

‐ day)

= Hand to Mouth + Dermal

Source: US EPA (2006). Reregistration Eligibility Determination for Dichlorovos (DDVP) EPA 738

‐ R

‐ 06

‐ 013Supp. to NRDC petition to cancel pet collar uses for propoxur

Docket ID No. EPA-HQ-OPP-2007-0935 13

Appendix B: Cancer Risk Assessment

Cancer Risk

= Sum(Cancer potency factor *dose *lifetime exposure weighting factor)

Lifetime exposure weighting factor

= number of years in group/70

Table 4: Residential post application for hand

‐ to ‐ mouth and dermal exposures using EPA (2010)

transferable residue calculations and exposure parameters from EPA risk assessments for other pet

collars –CHILD (0

– 5 years)

Variable Source Wellmark

Dog Collar Wellmark

Cat Collar Sergeant’s

Dog Collar Sergeant’s

Cat Collar

Weight of the collar

(g)

EPA (2010)

Residential

Exposure and Risk

Assessment for

Propoxur

Formulated Pet

Collars 34 10.5 30 14

AR (Wellmark 10%

‐ Sergeant’s 9%) (g) 3.4 1.05 2.7 1.26

F(AR) 0.2 0.2 0.2 0.2

SA(pet) (cm2) 5986 2737 5986 2737

SAL 0.5 0.5 0.5 0.5

SA(hands) (cm2) 20 20 20 20

BW (kg) 15 15 15 15

SA(hug) 1875 1875 1875 1875

Mouthing events

(events/hr) EPA (2006) CRA for

Organophosphates 9 9 9 9

Duration of exposure

(hrs/day) EPA (2006) RED

DDVP 2 2 2 2

Freq (mouthing

events/day) 18 18 18 18

Freq (events/day) 1 hug per day

scenario 1 1 1 1

Fraction absorbed EPA (1997)

Propoxur RED 0.2 0.2 0.2 0.2

Daily Transferable

residue (mg/cm2

‐ day) 0.008 0.005 0.006 0.006

Dose (mg/kg

‐ day)

‐

ingestion 0.091 0.061 0.072 0.074

Dose (mg/kg

‐ day)

‐

dermal 0.189 0.128 0.150 0.153

Total Dose (mg/kg

‐ day) 0.280 0.189 0.223 0.227Supp. to NRDC petition to cancel pet collar uses for propoxur

Docket ID No. EPA-HQ-OPP-2007-0935 14

Table 5: Residential post application for only dermal exposures using EPA’s Transferable Residue

Assumptions

– and exposure parameters from EPA risk assessments for other pet collars. ADULT (6

– 70

years)

Variable Source Wellmark

‐ Dog

Collar Wellmark

Cat Collar Sergeant’s

Dog Collar Sergeant’s

Cat Collar

Weight of the collar (g)

EPA (2010)

Residential Exposure

and Risk

Assessment for

Propoxur

Formulated Pet

Collars 34 10.5 30 14

AR (Wellmark 10%

‐ Sergeant’s 9%) (g) 3.4 1.05 2.7 1.26

F(AR) 0.2 0.2 0.2 0.2

SA(pet) (cm2) 5986 2737 5986 2737

BW (kg) 70 70 70 70

SA(hug) 5625 5625 5625 5625

Freq (events/day) 1 hug per day

scenario 1 1 1 1

Fraction absorbed EPA (1997) Propoxur

RED 0.2 0.2 0.2 0.2

Daily Dislodgeable

residue (mg/cm2

‐ day) 0.008 0.005 0.006 0.006

Dose (mg/kg

‐ day)

‐

dermal 0.122 0.082 0.097 0.099Supp. to NRDC petition to cancel pet collar uses for propoxurDocket ID No. EPA-HQ-OPP-2007-09351515Table6:CancerRiskAgecategoryDosemg/kg‐dayCancerPotencyFactorweightingfactorRiskWellmarkDogCollarWellmarkCatCollarSergeant’sDogCollarSergeant’sCatCollarWellmarkDogCollarWellmarkCatCollarSergeant’sDogCollarSergeant’sCatCollar0to<60.2800.1890.2230.2270.00370.098.89E‐058.89E‐058.89E‐058.89E‐056to700.120.080.100.100.00370.914.12E‐044.12E‐044.12E‐044.12E‐04Total‐lifetime15.01E‐045.01E‐045.01E‐045.01E‐04Total‐lifetimepermillion501501501501