Pilot Study of The Potential for Human Exposures to Pet-borne Diazinon Residues Following Lawn Applications in North Carolina

Abstract

This study examined the potential for indoor/outdoor pet dogs to transport and translocate
diazinon residues into homes and onto occupants following residential lawn applications.
One primary objective was to investigate the potential exposures of children and their pet
dogs to diazinon after a lawn application at their homes. Six families and their pet dogs were
recruited into the study within a 50-mile radius of the Research Triangle Park area of North
Carolina. Monitoring was conducted at pre-, 1, 2, 4, and 8 days post-application of a
commercial formulation of diazinon by the homeowner. Environmental samples that were
collected consisted of indoor air, soil, dust, and transferable residues from lawns and floors.
First morning void urine samples were collected from both a child (<14 years) and their
parent. Samples taken from the dogs included fur clippings, paw wipes, and transferable
residues using cotton gloves. Transferable residues were collected from dogs by a
technician, stroking the dog five times (head-to-rump) each sampling day and by each child
playing with their pet for 15-minutes on Day 2 post-application. All samples were analyzed for
diazinon, except for urine, by GC/MS. Urine samples were analyzed for 2-isopropyl-6-methyl-
pyrimidin-4-ol (IMPy), the specific metabolite for diazinon, by HPLC/MS-MS. We report here
the levels of diazinon measured in fur clipping, paw wipe, and transferable residue samples
and urinary IMPy concentrations for children and adults.

Results

Paw wipes (Figure 1a). The mean loadings of diazinon on the dogs' paws were over 900 times greater on day 1 post-application (88.1±100.1 ng/cm2)
compared to pre-application (<0.09 ng/cm2), and these residues remained elevated above background levels up to day 8 post-application.

Fur clippings (Figure 1 b). The levels of diazinon on the fur clippings were on average at least 14 times higher on each sampling day post-application
than at pre-application of diazinon (0.8+0.4 ng/cm2) to the lawns.

Cotton glove (Technician; Figure 1c). The mean loadings of diazinon were highest on the technician's glove samples on day 1 post-application
(10.4+23.9 ng/cm2), but declined substantially by day 2 post-application (1.3+1.4 ng/cm2).

Cotton gloves (Child; Figure 1 d). The loadings of diazinon on the children's cotton glove samples ranged from <0.01 ng/cm2 to 53.7 ng/cm2 on
day 2 post-application.

Urine (Figure 2). IMPy concentrations for the participants' ranged from <0.3 to 5.5 ng/mL before application and <0.3 ng/mL to 12.5 ng/mL after
application of diazinon. The maximum IMPy concentrations occurred for one child (6.2 ng/mL) and one adult (12.5 ng/mL) from different households
on Day 1 post-application of diazinon to turf. The mean urinary IMPy concentrations for children or adults were not statistically different (p<0.05) at
pre-application compared to post-application of diazinon to turf at these homes.

Introduction

Diazinon is an organophosphorus insecticide that was commonly used to control for insect pests
on residential lawns and gardens. About 4 million lbs of diazinon were applied annually at
residences in the United States until December 2004. The U.S. Environmental Protection Agency
(USEPA) restricted the use of this insecticide for almost all residential and other similar settings
(e.g., schools, parks) where children could be potentially exposed (USEPA, 2006).

A few studies have reported the intrusion of diazinon inside homes after outdoor applications on
lawns or perimeters of residences (Lewis et al., 2001; Morgan et al., 2001). These studies have
suggested that the applied diazinon was likely being tracked in by occupants or migrating by air
into homes after outdoor applications. In addition, pet dogs may be an important factor for the
intrusion of pesticides such as diazinon into homes after lawn applications (Morgan etal., 2001;
Nishioka et al., 2001). Pesticide residues tracked in by pet dogs may be deposited onto surfaces
and volatilize or resuspended into air, potentially exposing occupants. In addition, pets may
transfer pesticides to humans through direct intimate contact such as petting, playing, kissing,
licking and resting on laps (Boone et al, 2001; Morgan et al., 2001). Residues sorbed to pet hair
and skin may readily transfer to human hands or clothing during such contacts as well.

Humans can be potentially exposed to this semi-volatile insecticide through the inhalation,
ingestion, and dermal routes of exposure. Once diazinon is absorbed, it is rapidly metabolized
into several metabolites including diethylphosphate (DEP), diethylthiophosphate (DETP), and
2-isopropyl-6-methyl-4-pyrimidiol in the body (IMPy; Garfitt et al., 2002; CDC, 2005). IMPy is
commonly used as the specific urinary biomarker of exposure to diazinon.

In this observational study, the objectives were to investigate the potential exposures of
occupants and their pet dogs to diazinon after a lawn application at their homes and determine if
intimate contacts between occupants and their pet dogs resulted in measurable exposures.

Study Design

Participants

¦ Six families with a child (<14 yrs.) and
pet dog (>1 yr)

¦ Homeowner planning to apply a granular
formulation of diazinon to the lawn

Norlli Carolina

Study Site

¦ Piedmont area of North Carolina
• Single family residences

Duration

• Study conducted from April to
August 2001

• Field sampling occurred over a
9-day period at each home

The study protocol and procedures to obtain the assent of the

were reviewed and approved by an Independent Institutional
rev/ew board (IRB) and complied with all applicable requirements
of the Common Rule regarding additional protections for child ten.

Sampling Protocol

Table 1 shows the types of samples that were collected at pre-application and 1, 2, 4, and 8
days post-application of diazinon to residential lawns. Results for the personal samples
collected in this study (purple text) are presented in this poster.

Table 1. Samples collected at each home during the study.

Medium Pre 12 4 8

Air (Living Room)

Air (Child's Bedroom)

PUF Roller (Turf)

PUF Roller (Indoors)

Soil

Entryway (Doormat)

Track-in (HVS3)

Urine Void (Adult)3

Urine Void (Child)3

Fur Clippings (Dog)

Paw Wipes (Doq)

Cotton Gloves (Child)

Cotton Glove (Technician)

"First morning void

Participant Information

The children's ages ranged from 5 to 13 years. Four of the children were female and
two were male. Table 2 has shown the physical characteristics of the pet dogs in this study.

Table 2. Physical characteristics of the dogs.

Dog

Age

(yr)

Gender

Weight
(lbs)

Breed

Hair Type

Dog 1

Male

Bulldog/Boxer mix

Short

Dog 2

Female

Basset Hound/Saint

Bernard/
Golden Retriever mix

Medium

Dog 3

Male

Lhasa Apso

Medium

Dog 4

Male

Pomeranian

Long

Dog 5

Female

Black Labrador

Short

Dog 6

Male

Alaskan Malamute

Long

st due to laboratory error

Figure 1a. Mean loadings of diazinon on the paws of the dogs at
each sampling interval.

Figure 1b. Mean loadings of diazinon on the fur of dogs s
sampling interval.

Figure 1c. Mean loadings of diazinon on the cotton glove worn
by the technician at each sampling interval.

Figure 1d. Mean loadings of diazinon on the cotton gloves
worn by each child on day 2 post-application.

References

* Boone, J.S., Tyler, J.W., and Chambers, J.E. Transferable residues from dog tiirand plasma cholinesterase inhibition in dogs treated with a flea control dip containing
chlorpyrifos. Environ. Health Perspect. 2001:109:1109-1114.

* CDC (Centers for Disease Control and Prevention). 2005. Third rational report on human exposure to environmental chemicals, http://wvivw.cdc.aov/exposurerepott/.

* Garfitt, S.J, Jones, K. Mason, H.J., and Cocker, J. Exposure to the organophosphate diazinon: data from a human volunteer study with oral and dermal doses.
Toxicology Letters. 2002:134:105-113.

* Lewis, R.G., Forture, C.R., Blanchard, F.T., and Camann, D.E. Movement and deposition of two organophosphorus pesticides within a residence after interior and
exterior applications. J. Air & Waste Mange. Assoc. 2001: 51: 339-351.

* Morgan, M.K., Stout, D.M., and Wilson, N.K. Feasibility study of the potential for human exposure to pet-bome diazinon residues following lawn applications.

Bull. Environ. Toxicol. 2001: 66:295-300.

* Nishioka, N.G., Lewis, R.G., Brinkman, M.C., Burkholder, H.M., Hines, C.E., and Menkedick, J.R. Distribution of 2,4-D in air and on surfaces inside residences after
lawn applications: comparing exposure estimates from various media for young children. Environ. Health Perspect. 2001:109: 1185-1191.

* USEPA. Diazinon. 2006 http://wAv.eDa.aov/pesticides/oD/di3zinon.htm

Disclaimer: Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.

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