2, 4-D levels in the Homes and Urine of 135 Preschool Children and their Adult Caregivers

2,4-D levels in the Homes and Urine of 135 Preschool
Children and their Adult Caregivers

M.K. Morgan1, LS. Sheldon1, C.W. Croghan1, P.A. Jones1, K.W. Thomas1, J.C. Chuang2, and N.K. Wilson3.1USEPA, National
Exposure Research Laboratory, RTP, NC, USA; 2Battelle, Columbus, OH, USA; and 3Battelle, Durham, NC, USA

Abstract

Context

The aggregate exposures of 135 preschool children and their primary adult caregivers to chemicals
commonly found in their everyday environments were investigated. One objective was to identify sources
and pathways of the participants' exposures to the herticide 2,4-dichlorophenoxyacetic acid (2,4-D) at
their homes.

Methods

Participants were recruited randomly from selected homes in six North Carolina (NC) and six Ohio (OH)
counties. Monitoring was performed over a 48-h period at the participants' homes. Environmental samples
collected at the homes included soil, carpet dust, indoor air, and outdoor air (Table 1). Personal samples
collected from both children and adults consisted of hand wipes, solid food, liquid food, and urine. All
samples were analyzed by gas chromatography/mass spectrometry (GC/MS) for 2,4-D (acid form).

Results

2,4-D was detected in all environmental and personal media, but was most often in dust (>82%) and urine
(>86%). The median levels of 2,4-D in dust samples were at least three times lower in the NC homes (47.5
ng/g) than in the OH homes (156 ng/g). In addition, 2,4-D was detected in 8% compared to 49% of the
hand wipe samples from NC children and OH children, respectively. Similarly, it was detected in 5%
compared to 63% of the hand wipe samples from NC adults and OH adults, respectively. The median
urinary concentrations of 2,4-D were two times lower for NC children (0.5 ng/mL) than for OH children (1.2
ng/mL). However, the median urinary concentrations of 2,4-D were similar for NC adults (0.6 ng/mL) and
OH adults (0.7 ng/mL).

Discussion

This information suggests that 2,4-D may have been more commonly used at the selected homes in OH
than in NC. The results overall showed that these participants were potentially exposed to 2,4-D from
several sources and pathways at their homes. In addition, the urinary 2,4-D levels confirmed that these
preschool children and their adult caregivers were exposed to low levels of 2,4-D in their daily
environments.

Introduction

2,4-Dichlorophenoxyacetic acid (2,4-D) is an aryloxyalkanoic acid herticide that is commonly used to control for
broadieaf weeds in agricultural and residential settings in the US (Baker et al., 2000; Arbuckle and Ritter; 2005;
US EPA, 2005). Over 40 million lbs of 2,4-D are applied annually in this country, mainly in agriculture (~70%) and
to a lesser extent at residences (~25%) on lawns and gardens (USEPA, 2005).

A few small studies have recently reported detecting low levels of 2,4-D in media at children's homes in the United
States (Nishioka et al., 2001; Wilson et al., 2003). Wilson showed that 2,4-D residues were measurable at low
levels in soil, air, carpet dust, and food samples collected at nine preschool children's homes in NC. Nishioka
reported measuring low concentrations of 2,4-D in carpet dust and surface wipe (floors, tabletops, and window
sills) samples at several children's homes in the Midwest.

Humans can be exposed to 2,4-D through inhalation, ingestion, and dermal routes of exposure. Once 2,4-D is
absorbed into the body, it is rapidly eliminated unchanged in the urine (Knopp and Glass; 1991; Garabrant and
Philbert, 2002). The biological half-life of 2,4-D through oral ingestion ranges from 10 to 33 hours in humans
(Kohli et al., 1974; Sauertioff et al., 1977; CDC, 2005). A few studies have recently reported measuring low levels
of 2,4-D (< 3.5 ng/mL) in urine samples from non-occupationally exposed adults and children in the US (Wilson et
al., 2003; CDC, 2005; Curwin et al., 2005).

In this work, we quantified the distributions of 2,4-D in environmental and personal media for 135 preschool
children and their adult caregivers at homes in NC and OH. We examined potential sources and pathways of the
participants' exposures to this herticide.

Study Design

The Study

The Children's Total Exposure to Persistent Pesticides and Other Persistent Organic Pollutants
(CTEPP) study was an observational study that investigated the aggregate exposures of 257 preschool
children and their adult caregivers to chemicals commonly found in their everyday environments. As
part of this study, we investigated the exposures of non-daycare participants to 2,4-D at their homes in
NC and OH. One important hypothesis of this study was whether children's exposures to targeted
pollutants were significantly greater than those of adults living in the same household.

Participants

Preschool children, ages 2 to 5 years, and their adult caregivers were randomly recruited from homes in
six NC and six OH counties. The participants were recruited by field staff between February 2000 and
February 2001 in NC and January 2001 and November 2001 in OH. We successfully recruited 66 and
69 preschool children and their adult caregivers in NC and OH, respectively. A total of 135 preschool
children and their adult caregivers completed the study (Table 2).

The study protocol and procedures to obtain the assent of the children and informed consent of their parents or guardians
were reviewed and approved by an independent institutional review board (IRB) and complied with all applicable requirements
of the Common Rule regarding additional protections for children.

Sampling

Table 1. Environmental and personal samples collected over a
48-h period at the participants' homes in NC and OH

- Food

- Drinking Water

- Hand Wipes

- Beverages

- Indoor Air

- Play Area Soil

- Urine

- Outdoor Air

- Floor Dust

Table 2. Demographic characteristics of the participants

Children

Adults

Age (yr)

Median

3.4

3.9

Range

1.7-5.4

1.9-5.6

20-44

19-49

Gender

Female

61%

48%

95%

90%

Male

39%

52%

10%

Results

For the OH participants, the levels of 2,4-D were higher in their dust and hand wipe samples. In addition, the OH children had higher urinary 2,4-
D concentrations than the NC children. The distributions of 2,4-D concentrations in the participants' dust, hand wipe, solid food, and urine
samples are shown in Figure 1.

Dust (Figure 1a). 2,4-D was detected most often in dust samples (>82%). However, median levels of 2,4-D in the dust samples were three
times lower in the sampled NC homes than in OH homes (47.5 vs. 156 ng/g, p<0.0002).

Hand wipes (Figure 1b). 2,4-D was detected in 8% compared to 49% of hand wipe samples for NC and OH children, respectively. Similarly, it
was detected in 5% compared to 63% of the hand wipe samples from NC and OH adults, respectively. At the 95th percentile, the levels of 2,4-D
were at least five times lower for the NC participants than for the OH participants. In addition, at the 95th percentile, 2,4-D concentrations in hand
wipe samples were at least three times higher for OH children compared to OH adults.

Solid food (Figure 1c). The levels of 2,4-D in the solid food samples were below 7 ng/g for all participants, except for one OH child with a
maximum value of 20.2 ng/g.

Urine (Figure 1d). The median concentrations of 2,4-D in urine were two times lower for NC compared to OH children (0.5 vs. 1.2 ng/mL,
p<0.0001). In contrast, the median 2,4-D concentrations were similar for NC compared to OH adults (0.6 vs. 0.7 ng/mL). The maximum levels of
2,4-D were 12.5 ng/mL for one child and 7.3 ng/mL for one adult from different households in OH.

Figure 1 a. Distribution of 2,4-D in dust samples at
homes in NC and OH.

Figure 1b. Distribution of 2,4-D in hand wipe samples
for participants at homes in NC and OH.

Figure 1c. Distribution of 2,4-D in solid food samples
for participants at homes in NC and OH.

Figure 1d. Distribution of urinary 2,4-D concentrations
for participants at homes in NC and OH.

References

Arbuckle, T.E. and Ritter, L. Phenoxyacetic acid herticide exposure for worn en on Ontario farms. J. Toxicol. Environ. Health A. 2005: 68: 1359-1370.
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high-performance liquid chromatography/tandem mass spectrometry. J. Expo. Anal. Environ. Epidemiol. 2000:10: 789-798.

CDC (Centers for Disease Control and Prevention). 2005. Third national report on human exposure to environmental chemicals.

http .11Www. cd c. a ov/exp osu rerep ort/.

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levels among farmers and nonfarmers in Iowa. J. Expo. Anal. Environ. Epidemiol. 2005:15: 500-508.

Garabrant, D.H. and Philbert, M.A Review of 2,4-dichlorophenoxyacetic acid (2,4-D) epidemiology and toxicology. Crit. Rev. Toxicol. 2002: 32(4): 233-257.
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Nishioka, M.G., Lewis R.A, Brinkman, M.C., Burkerholder, H.M., Hines, C.E., and Menkedick, J.R. Distributions of 2,4-D in air and on surfaces inside
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Disclaimer: Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.

Discussion

* These children and their adult caregivers in NC and OH were likely exposed to low levels of 2,4-D through
several pathways and routes of exposure at their homes.

* The results suggest that 2,4-D was likely being tracked in by occupants and/or transported through air
intrusion into homes after outdoor applications.

* This information suggests that 2,4-D may have been more commonly used at homes in OH than in NC.

* The urinary biomarker of exposure, 2,4-D itself, confirmed that most of these preschool children and their
adult caregivers were exposed to low levels of 2,4-D in their daily environments.

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