Grantee Research Project Results

2005 Progress Report: Longitudinal Study of Children's Exposure to Permethrin

EPA Grant Number: R829397
Title: Longitudinal Study of Children's Exposure to Permethrin
Investigators: Raymer, James H. , Hu, Ye A. , Akland, Gerald G.
Current Investigators: Raymer, James H. , Hu, Ye A. , Michael, L. C. , Studabaker, W.
Institution: Desert Research Institute
EPA Project Officer: Aja, Hayley
Project Period: February 18, 2002 through February 17, 2005 (Extended to July 17, 2006)
Project Period Covered by this Report: February 18, 2005 through February 17, 2006
Project Amount: $754,664
RFA: Children's Vulnerability to Toxic Substances in the Environment (2001) RFA Text |  Recipients Lists
Research Category: Environmental Justice , Human Health , Children's Health

Objective:

The specific objectives of the research project are to: (1) investigate the time course of the redistribution of pyrethroid pesticides in various media following application and factors affecting the redistribution; (2) investigate the functional relationships across time between pesticide concentrations in environmental media, personal measurements, and biological media; (3) estimate aggregate exposure after application and the importance of each exposure pathway; and (4) investigate the difference between the time course of pyrethroid pesticide metabolism for adults and children.

Progress Summary:

We are into the final 6 months of this project as a result of the approved 6-month, no-cost extension. The additional 6 months was requested and approved in anticipation that additional urine samples could be analyzed (see below).

Sample Analysis

The samples, except for foods and diaper urines, have been extracted and analyzed. Table 1 provides preliminary results of target compound concentrations from hand wipes, surface wipes, toy wipes and air samples. The results indicate a wide range of surface loadings of the target compounds in these homes. The highest median and maximal surface loading was observed for deltamethrin, with values of 2.3 and 160 ng/cm², respectively. Preliminary data from the hand wipes indicates potential for dermal uptake of pyrethroids from the surfaces. Toy wipes generally showed low surface loadings. Very low concentrations were measured in air and likely reflect the low vapor pressures of the pyrethroids.

Table 1. Summary Statistics for Analytes from Hand, Surface, and Toy Wipes, and Air

SAMPLE MEDIUM	CONC UNIT	CHEMICAL SPECIES	NO. OBS.	MEAN LOAD	STD DEV	MIN	25TH PERC.	MEDIAN	75TH PERC.	MAX
Hand Wipe	ng/cm2	Cypermethrin	2	4.6	3	2.5	2.5	4.6	6.7	6.7
Hand Wipe	ng/cm2	Deltamethrin	3	8.2	5.2	4.2	4.2	6.3	14	14
Hand Wipe	ng/cm2	Permethrin	8	3.4	4.1	0.44	0.6	1.4	5.5	12
Hand Wipe	ng/cm2	cis-Permethrin	6	2	1.9	0.29	0.57	1.3	3.1	5.3
Hand Wipe	ng/cm2	trans-Permethrin	12	1.3	2	0.063	0.16	0.49	1.6	6.6
Surface Wipe	ng/cm2	Cyfluthrin	75	2.7	6.3	0.097	0.32	0.57	1.4	39
Surface Wipe	ng/cm2	Cypermethrin	123	9.8	23	0.098	0.3	0.7	5.7	120
Surface Wipe	ng/cm2	Deltamethrin	200	7	19	0.21	0.91	2.3	4.7	160
Surface Wipe	ng/cm2	L-Cyhalothrin	98	2.8	5.2	0.02	0.034	0.33	4	29
Surface Wipe	ng/cm2	Permethrin	224	5.5	10	0.025	0.33	0.97	6.4	71
Surface Wipe	ng/cm2	cis-Permethrin	211	2.8	4.9	0.021	0.17	0.51	3.2	31
Surface Wipe	ng/cm2	trans-Permethrin	224	3.1	5.8	0.025	0.18	0.72	3.7	39
Toy Wipe	ng/cm2	Cyfluthrin	3	0.44	0.058	0.41	0.41	0.41	0.51	0.51
Toy Wipe	ng/cm2	Cypermethrin	8	5.1	3.7	0.5	3.3	4	7.3	11
Toy Wipe	ng/cm2	Deltamethrin	1	6.9		6.9	6.9	6.9	6.9	6.9
Toy Wipe	ng/cm2	L-Cyhalothrin	5	1.1	1	0.34	0.36	0.44	2.2	2.2
Toy Wipe	ng/cm2	Permethrin	23	0.4	0.28	0.13	0.2	0.26	0.62	1
Toy Wipe	ng/cm2	cis-Permethrin	14	0.24	0.11	0.095	0.11	0.27	0.31	0.41
Toy Wipe	ng/cm2	trans-Permethrin	20	0.43	0.35	0.069	0.15	0.3	0.68	1.2
Air	ng/L	Cyfluthrin	1	0.0033		0.0033	0.0033	0.0033	0.0033	0.0033
Air	ng/L	Cypermethrin	19	0.089	0.061	0.0082	0.025	0.078	0.17	0.18
Air	ng/L	Deltamethrin	13	0.06	0.028	0.031	0.039	0.051	0.097	0.1
Air	ng/L	L-Cyhalothrin	35	0.009	0.0053	0.0025	0.0059	0.0079	0.011	0.024
Air	ng/L	Permethrin	41	0.022	0.027	.	0.0039	0.0082	0.035	0.11
Air	ng/L	cis-Permethrin	38	0.011	0.014	.	0.0016	0.0038	0.018	0.054
Air	ng/L	trans-Permethrin	40	0.016	0.018	.	0.004	0.0069	0.026	0.073

We have completed the liquid chromatography-tandem mass spectroscopy analysis of adult urine samples and urine samples from toilet-trained children. Pyrethroid metabolites 3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclo-propane) carboxylic acid (DCCA), 3-(2,2-dibromovinyl)-2,2dimethyl-(1-cyclo-propane) carboxylic acid (DBCA) and 3-phenoxybenzoic acid (3-PBA) concentrations in the analyzed samples are summarized in Table 2. Preliminary results indicate that metabolites were found in a small fraction of the samples (≤ 11%). Further statistical analysis will be performed, as permitted by resources, at the completion of the analysis of the remaining children’s urine samples. A key question is the temporal relationship between pesticide application and the appearance of metabolites in urine. Some initial data are presented below.

Table 2. Pyrethroid Metabolite Concentration in Urine Samples

SAMPLE MEDIA	CONCUNIT	CHEM SPECIES	NO. OBS	MEAN CONC	STD DEV	MIN	25TH %	MEDIAN	75TH %	MAX	% MEAS
Adult Urine	ng/mL	DCCA	208	0.016	0.06	0	0	0	0	0.55	4
Adult Urine	ng/mL	3-PBA	208	0.072	0.21	0	0	0.016	0.049	1.8	9
Adult Urine	ng/mL	DBCA	208	0.03	0.16	0	0	0	0	1.4	4
Child Urine	ng/mL	DCCA	57	0.02	0.065	0	0	0	0	0.34	7
Child Urine	ng/mL	3-PBA	57	0.069	0.14	0	0	0.032	0.054	0.72	11
Child Urine	ng/mL	DBCA	57	0.01	0.032	0	0	0	0	0.17	4

Some example data from the first month sampling period are presented in Figure 1. Cyfluthrin and pyrethrins were applied professionally on the day shown by the green (lone open) circle. The closely spaced points reflect the first week of daily sample collection. Measured concentrations are quite low and the surface wipes do not show an increase following application. Figure 2 shows the entire sampling period.

Figure 1. Data From First Month of Sampling for Participant 4 Where Cyfluthrin Was Applied

Figure 2. Air and Wipe Measurements for the Entire Sampling Period for Participant 4

Pesticides measured in surface wipes do not show clear increases following applications but rather a persistent presence with surface residues, perhaps influenced by activities that facilitate the translocation of dust. An overlay of 3-PBA in urine and environmental measures of permethrin in the home of participant 4 is shown in Figure 3. The concentrations of 3-PBA in adult and child urine loosely track each other, with the concentration in adult urine being higher than in child urine, opposite of what would be anticipated. This could be suggestive of slower metabolism and elimination in children.

Figure 3. Permethrin (Surface Wipe) from Participant 4 Shown With Adult (Red) and Child (Green) Urine

An evaluation of surface concentrations of nonapplied pesticides for participant 9 is shown in Figure 4. Cypermethrin was the applied pesticide, the concentration of which is substantially smaller than those for the nonapplied compounds; prior history of pesticides used is not known. The fact that cyhalothrin and deltamethrin track each other suggests that they are adsorbed to particles and that activities in the household are affecting resuspension.

Conclusions that can be reached, pending additional analysis, are as follows:
Air pesticides are measured at low concentrations (likely from suspended dust). Hand and toy wipes typically showed very low pesticide residues. Nonapplied pesticides consistently were detected, possibly from previous applications. Pesticides appear to persist in the indoor environment and do not increase substantially following applications. Limited urine data suggest child concentrations lower than adult (participant 004; twins 005 and 009—not shown). This might suggest a reduced ability of children to metabolize and excrete pyrethroids.

Figure 4. Surface Loadings of Pesticides in the Home of Participant 9

Future Activities:

The major goal of the final 6 months will be to complete data analysis and reporting. Budgetary limitations will preclude analysis of the food samples. Urine from diapers might possibly be analyzed on another ongoing project.

Journal Articles:

No journal articles submitted with this report: View all 9 publications for this project

Supplemental Keywords:

pyrethroid pesticides, children, longitudinal, disposable diapers, exposure modeling, body dosimeter, children, exposure, exposure assessment, exposure pathways, functional relationships, human exposure, human health risk, longitudinal study, metabolism, multi-pathway study, permethrin, pesticides,, RFA, Scientific Discipline, Health, Health Risk Assessment, Chemistry, Risk Assessments, Disease & Cumulative Effects, Children's Health, Biology, multi-pathway study, permethrin, pesticides, functional relationships, urinary metabolite, exposure, children, longitudinal study, body dosimeter, human exposure, exposure pathways, metabolism, exposure assessment

Progress and Final Reports:

Original Abstract

2002 Progress Report

2003 Progress Report

2004 Progress Report

Final Report