Grantee Research Project Results
Final Report: Longitudinal Study of Children's Exposure to Permethrin
EPA Grant Number: R829397Title: Longitudinal Study of Children's Exposure to Permethrin
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 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:
Pesticides are applied in and around dwellings to control a variety of pests. The pesticides used have varied as the knowledge of their environmental persistence and potential for human exposures and health effects has grown. The cyclodiene insecticides, such as chlordane and heptachlor, were voluntarily withdrawn from the market in 1988 and were replaced by pyrethroids and organophosphate (OP) pesticides. Of these, chlorpyrifos and permethrin emerged as termiticides of choice by commercial applicators (Leidy, et al., 1993). Increased attention to the potential for high indoor exposure to OPs has resulted in cancellations by the U.S. Environmental Protection Agency (EPA) of the two pesticides most commonly used indoors, chlorpyrifos and diazinon. These changes led to the further increased use of pyrethroids.
Permethrin has been found in 90% of the house dust in homes in Germany (Friedrich, et al., 1998) and 24% of homes in the United States (Adgate, et al., 2000). Introduced to the market in 1977, permethrin is a broad-spectrum pesticide widely used in agriculture and residential environments. As a neurotoxin, permethrin acts on the sodium channel of the excitatory nerves (Miyamoto, et al., 1995). A recent study demonstrates that the enzymes involved in detoxification of permethrin were less active in young rats than adults (Miyamoto, et al., 1995). Since children are at the critical stage for neurological development, further understanding of permethrin exposure and toxicity is important.
A study, funded under this grant, was conducted in which 13 homes, each containing an adult and at least one child under the age of 3, were monitored many times over the course of several months. Environmental samples, food samples, personal samples, and biological samples were collected.
The specific aims of the research program were to: (1) investigate the time course of the redistribution of pyrethroid pesticides in various media following application and the factors affecting the redistribution; (2) investigate the functional relationships across time between 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 in adults and in children.
Summary/Accomplishments (Outputs/Outcomes):
Institutional Review Board (IRB) Approvals/Protocols
An IRB research protocol was prepared and submitted to the Research Triangle Institute (RTI) IRB. The protocol and associated informed consent form and questionnaires were reviewed and approved. Documentation of approval was provided to EPA.
Recruitment
Criteria for inclusion of a home in the study were that both an adult caregiver and a child between the ages of 1 and 3 lived in the same home and stayed at home during the day (i.e., the child was not in day care), and that pyrethroid pesticides had been applied or were to be applied in the home at least one time by either a professional applicator or by someone in the home. All pesticide applications were initiated exclusively by the participant and conducted only by the participant or someone hired by the participant. Extreme care was exercised during all phases of the recruitment and sample collection processes to insure that absolutely no encouragement was provided to the participant to apply pesticides to their home. The final list of participants, the pesticides applied, the application type and frequency, and the initial application and visit dates appear in Table 1.
Table 1. Participants Recruited. A total of 13 homes and 15 adult/child pairs were recruited.
Participant ID |
Child’s Age at Beginning of Study (months) |
Pesticide Applied |
Application Type |
Application |
First Application Date |
First Visit Date |
001 |
14 |
Cyfluthrin |
Professional |
Once |
8/6/2003 |
8/4/2003 |
002 |
30 |
Deltamethrin |
Professional |
Quarterly |
5/14/2003 |
5/9/2003 |
003 twin |
26 |
Deltamethrin |
Professional |
Quarterly |
5/14/2003 |
5/5/2003 |
004 |
45 |
Cyfluthrin + |
Professional |
Every other month |
5/27/2003 |
5/23/2003 |
005 twin |
25 |
Cypermethrin |
Professional |
Quarterly |
12/2/2003 |
11/24/2003 |
006 |
22 |
Permethrin |
Self |
As needed during summer |
7/14/2003 |
7/10/2003 |
007 |
20 |
Deltamethrin |
Professional |
Quarterly |
6/3/2003 |
6/2/2003 |
008 |
12 |
Cyfluthrin |
Professional |
Every other month |
7/9/2003 |
5/30/2003 |
009 twin |
25 |
Cypermethrin |
Professional |
Quarterly |
12/2/2003 |
11/24/2003 |
010 |
25 |
Permethrin |
Self |
As needed during fall |
9/25/2003 |
9/24/2003 |
011 |
15 |
Permethrin |
Self |
As needed |
10/22/2003 |
10/20/2003 |
012 |
29 |
Cypermethrin |
Self |
As needed |
6/24/2003 |
6/20/2003 |
013 twin |
26 |
Deltamethrin |
Professional |
Quarterly |
5/14/2003 |
5/5/2003 |
014 |
14 |
Permethrin + |
Self |
As needed |
8/20/2003 |
8/18/2003 |
015 |
14 |
Cypermethrin |
Self |
As needed |
10/3/2003 |
10/1/2003 |
As shown in Table 1, there was no predominant pyrethroid pesticide applied indoors in the recruited households. Restricted by the availability of the households that use permethrin, we decided to slightly modify the objectives of the study. Rather than limiting the target list to permethrin, we expanded the list to include other pyrethroid pesticides. Although this will decrease the statistical power to build the permethrin redistribution model, it will allow comparison of the redistribution models in the pyrethroid pesticides family. The expansion of the target list was supported by the analysis of an expanded list of metabolites. The original proposal only required the capability to analyze 3-phenoxybenzoic acid. As demonstrated by Hu, et al. ( 2004), we can analyze 3-(2,2-Dichlorovinyl)-2,2-dimethyl-(1-cyclo-propane) carboxylic acid (DCCA) and 3-(2,2-Dibromovinyl)-2,2dimethyl-(1-cyclo-propane) carboxylic acid (DBCA) in disposable diapers.
Sample Collection
The sample collection strategy (Table 2) was such that intensive sampling occurred daily for the first 8 days—beginning the day before pesticide application—then once a week for the next 3 weeks, and then once every other month through month 12. This scheme was designed to permit characterization of both short-term and long-term pesticide concentrations as a result of redistribution in the environment. The environmental samples (air, surface wipe, toy wipe, and food) could be compared with urine samples to clarify the relative contribution to pesticide dose. Wipes used were Sof-Wick® 4- inch by 4- inch, six-ply dressing sponges (Johnson & Johnson). A new, 10-inch play ball was provided to each child at the start of the study so that each would start with a ball that had had no previous contact with pesticides. This also ensured that all the children would play with a toy that had the same shape and thus the same kind of contact with play surfaces, so as to avoid bias among homes in the study. The bodysuit (pajama) samples serve as a surrogate for potential dermal exposure. Videos were taken for a 1-hour period two times to document the children’s behaviors in an eating event. Questionnaires were used to collect additional information about the home, hygiene practices, and activities.
Table 2. Sampling Plan
Month |
|||||||||||||
Type |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
|
Week # 1 |
Week # 2–4 |
||||||||||||
Air |
8 |
||||||||||||
Surface wipe |
8 |
3 |
1 |
1 |
1 |
1 |
1 |
1 |
|||||
Toy wipe |
8 |
||||||||||||
Hand wipe |
8 |
3 |
1 |
1 |
1 |
1 |
1 |
1 |
|||||
Pajama |
8 |
1 |
|||||||||||
Leftover foods |
8 |
||||||||||||
Duplicate foods |
8 |
||||||||||||
Child urine |
8 |
3 |
1 |
1 |
1 |
1 |
1 |
1 |
|||||
Adult urine |
8 |
3 |
1 |
1 |
1 |
1 |
1 |
1 |
|||||
Video (1 hour) |
1 |
1 |
1 |
||||||||||
Questionnaire |
1 |
Air samples were collected for 24 hours on XAD resin, wipe samples (surface and toy) were collected using isopropanol-moistened gauze pads, and bodysuits were worn by the children for several hours each day of sample collection. Food samples were collected both as duplicate diet and as food that was leftover but handled by the child; the leftover, handled food allowed the estimation of contamination by contact with both the child’s hands and eating surfaces. Urine samples (first morning void) were collected in collection cups or on diapers. Following collection, samples were stored in a cooler (food, urine) until picked up by the field team. After being logged in, they were stored frozen at -20°C until prepared for analysis.
A total of 67% of the participants completed the entire 12-month study (10 out of 15 participants), 80% of participants completed at least 10 months of sample collection (12 out of 15 participants). Of the remaining three participants, two finished 8 months of sample collection, and one finished 6 months of sample collection.
Sample Analysis
Table 3 provides a summary of the sample extraction and analysis approach. Adult and child urine samples (non diaper) were analyzed for 3-PBA (3-phenoxybenzyl alcohol). The wipe samples, collected in homes occupied by persons with measured 3-PBA concentrations in urine, were then analyzed. Because of resource considerations encountered when poor recoveries were measured in q uality c ontrol (QC) samples, child diaper samples were not extracted and analyzed. Under similar resource constraints, food samples were also not analyzed. However, the availability of wipe data and urine data from adult/ child pairs was sufficient to evaluate: (1) relationships between surface residues, (2) redistribution of pesticides within the home, (3) changes over time between surface residues and urine concentrations, and (4) changes over time between adult and child concentrations. In addition, pajama samples provided good recovery, as measured by lab controls, yet poor recoveries of surrogate were measured from pajamas worn and soiled by the children. This indicated the need for additional method development, which was not possible within the resources available.
Table 3. Summary of Sample Extraction and Analysis Approaches Used
Matrix |
Sample preparation |
Analysis |
Air (AP) |
XAD extracted together in methylene chloride; sonicated; filtered; solvent volume reduced |
GC/MS-SIM |
Surface wipes (SW), |
Extracted with ethyl acetate; sonicated; solvent volume reduced |
GC/MS-SIM |
Pajama (WB) |
Extracted with 1:1 hexane:acetone; tumbled; solvent volume reduced; filtered |
GC/MS-SIM |
Leftover foods (LH) and duplicate foods (DD) |
Homogenized and aliquoted; mixed with ZnAc2 + Na2SO4; extracted with methylene chloride; partitioned with hexane; GPC cleanup |
GC/MS-SIM |
Child urine (CU) |
Extraction from diapers; no extraction from urine collected in cup |
LC/MS/MS |
Adult urine (AU) |
No extraction |
LC/MS/MS |
SIM = selective ion monitoring
GPC = gel permeation chromatography
LC = liquid chromatography
Summary Statistics
Summary statistics (across all homes and matrices) for the samples appear in Table 4. These data show the following:
- Percents measurable ranged from 0 to 95 across matrices and analytes with surface wipes and air samples exhibiting, overall, the greatest proportion of measurable results. Across matrices, permethrin tended to be measurable in the highest percentage of samples. Conversely, cyfluthrin tended to show the lowest proportion of measurable results. This could be reflective of the application method (self vs. professional). Cyfluthrin was applied professionally in three of the homes, while permethrin was self-applied in four of the homes. Self-applicators could have utilized higher application rates. However, the application frequency for permethrin might have been higher; this was not evaluated.
- The presence of extreme values on the high end of the distribution is seen for several compounds and matrices, notably deltamethrin and permethrin in hand wipes; cypermethrin, deltamethrin, and cy fluthrin in surface wipes; and cypermethrin on toy wipes.
Time Dependency of Sample Concentrations. Plots of sample concentrations, or loads versus time elapsed since initial pesticide application, were constructed for selected participants/homes and analytes, with homes chosen based on availability of data for multiple sample matrices. To facilitate comparisons across analytes and matrices, the plots were presented with all matrices on a common axis. This analysis was performed for a subset of five homes for which sufficient data were available for multiple matrices and analytes. Figure 1 provides an example of trends in pesticide levels over time.
Figure 1. Concentrations of Applied Pesticides in All Media Collected from a Given Home over Time. For hand wipe (HW), surface wipe (SW), toy wipe (TW), and air pesticide (AP), the applied compound was measured. For adult urine (AU) and child urine (CU), concentrations represent the common pyrethroid metabolite 3-PBA.
As sample analysis progressed, it became very apparent that non applied analytes were being measured in the homes. Since values were not corrected for method blanks, some instances of measurable concentrations of non applied pesticides could be the result of background. However, this is not true in many of the cases, as evidenced by the method blank information.
To facilitate visualization of trends, plots of concentration (ng/L) or load (ng/cm2) versus elapsed time were generated for each participant and sample matrix, displaying all analytes on the same plot (an example is shown in Figure 2). This analysis was performed for a subset of five homes for which sufficient data were available for all matrices and analytes.
Figure 2. Example Plots Showing All Study Target Pesticides (Applied and Not Applied) in Homes. Applied pesticides were cyfluthrin and pyrethrins for PARID = 004 (top) and cypermethrin for PARID = 12 (bottom).
These data suggest that pyrethroids are quite stable in the indoor environment, and the increases (not linked in time to an application), along with the fact that many of the compounds increased concurrently, support the notion that these compounds are adsorbed to dust particles and that mechanical redistribution is the primary transport mechanism in the home. This is consistent also with the low vapor pressures of the pyrethroids.
Table 4. Summary Statistics and Percents Measurable for Samples
Sample |
Conc. |
Chemical |
No. |
Mean |
Std. |
Minimum |
25th |
Median |
75th |
Maximum |
% |
Hand Wipe |
ng/cm2 |
Cyfluthrin |
25 |
0.038 |
0.12 |
0 |
0 |
0 |
0 |
0.52 |
0 |
Hand Wipe |
ng/cm2 |
Cypermethrin |
25 |
0.57 |
1.4 |
0 |
0 |
0 |
0.0019 |
6.7 |
8 |
Hand Wipe |
ng/cm2 |
Deltamethrin |
25 |
1.3 |
3.1 |
0 |
0 |
0 |
1.1 |
14 |
12 |
Hand Wipe |
ng/cm2 |
L-Cyhalothrin |
25 |
0.0061 |
0.027 |
0 |
0 |
0 |
0 |
0.13 |
0 |
Hand Wipe |
ng/cm2 |
Permethrin |
25 |
1.2 |
2.7 |
0 |
0 |
0.16 |
0.61 |
12 |
32 |
Hand Wipe |
ng/cm2 |
cis-Permethrin |
25 |
0.55 |
1.2 |
0 |
0.0048 |
0.066 |
0.29 |
5.3 |
24 |
Hand Wipe |
ng/cm2 |
trans-Permethrin |
25 |
0.67 |
1.5 |
0 |
0 |
0.091 |
0.31 |
6.6 |
48 |
Surface Wipe |
ng/cm2 |
Cyfluthrin |
211 |
0.98 |
3.9 |
0 |
0 |
0.057 |
0.35 |
39 |
37 |
Surface Wipe |
ng/cm2 |
Cypermethrin |
222 |
5.2 |
17 |
0 |
0.0008 |
0.18 |
0.79 |
120 |
55 |
Surface Wipe |
ng/cm2 |
Deltamethrin |
239 |
5.8 |
18 |
0 |
0.52 |
1.5 |
3.8 |
160 |
85 |
Surface Wipe |
ng/cm2 |
L-Cyhalothrin |
217 |
1.3 |
3.8 |
0 |
0.011 |
0.033 |
0.3 |
29 |
46 |
Surface Wipe |
ng/cm2 |
Permethrin |
238 |
5.1 |
9.6 |
0 |
0.28 |
0.79 |
5.3 |
71 |
94 |
Surface Wipe |
ng/cm2 |
cis-Permethrin |
239 |
2.4 |
4.6 |
0 |
0.095 |
0.34 |
2.7 |
31 |
88 |
Surface Wipe |
ng/cm2 |
trans-Permethrin |
237 |
2.8 |
5.4 |
0 |
0.15 |
0.64 |
2.8 |
39 |
95 |
Toy Wipe |
ng/cm2 |
Cyfluthrin |
54 |
0.047 |
0.15 |
0 |
0 |
0 |
0 |
0.76 |
6 |
Toy Wipe |
ng/cm2 |
Cypermethrin |
54 |
0.85 |
2.3 |
0 |
0.006 |
0.083 |
0.12 |
11 |
15 |
Toy Wipe |
ng/cm2 |
Deltamethrin |
54 |
0.71 |
1.1 |
0 |
0 |
0.46 |
1.2 |
6.9 |
2 |
Toy Wipe |
ng/cm2 |
L-Cyhalothrin |
54 |
0.21 |
0.41 |
0.0093 |
0.074 |
0.11 |
0.16 |
2.2 |
9 |
Toy Wipe |
ng/cm2 |
Permethrin |
54 |
0.24 |
0.23 |
0.0095 |
0.12 |
0.16 |
0.23 |
1 |
43 |
Toy Wipe |
ng/cm2 |
cis-Permethrin |
54 |
0.12 |
0.092 |
0.0073 |
0.063 |
0.11 |
0.12 |
0.41 |
26 |
Toy Wipe |
ng/cm2 |
trans-Permethrin |
42 |
0.23 |
0.31 |
0.001 |
0.02 |
0.1 |
0.27 |
1.2 |
48 |
Air |
ng/L |
Cyfluthrin |
53 |
0.0003 |
0.0016 |
0 |
0 |
0 |
0 |
0.011 |
12 |
Air |
ng/L |
Cypermethrin |
25 |
0.068 |
0.065 |
0 |
0.0082 |
0.061 |
0.097 |
0.18 |
77 |
Air |
ng/L |
Deltamethrin |
53 |
0.016 |
0.029 |
0 |
0 |
0 |
0.017 |
0.1 |
29 |
Air |
ng/L |
L-Cyhalothrin |
52 |
0.0055 |
0.006 |
0 |
0.0005 |
0.0044 |
0.0079 |
0.024 |
61 |
Air |
ng/L |
Permethrin |
54 |
0.017 |
0.025 |
0 |
0.0004 |
0.0058 |
0.022 |
0.11 |
73 |
Air |
ng/L |
cis-Permethrin |
53 |
0.0078 |
0.012 |
0 |
0.0002 |
0.0026 |
0.011 |
0.054 |
68 |
Air |
ng/L |
trans-Permethrin |
53 |
0.012 |
0.017 |
0 |
0.0002 |
0.0053 |
0.016 |
0.073 |
72 |
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 |
Following indoor application of pyrethroids, surface wipes taken from hard-floor surfaces near, but not at, the application areas (e.g., center of kitchen floor after crack and crevice application) showed both increases and decreases in surface loadings relative to samples collected before application. The low-level amounts of many non applied pyrethroid pesticides suggest that these pesticides are very stable in the indoor environment and can be distributed as a result of physical activity in the home.
Correlations Between Measurements for Different Sample Matrices. Significant correlations were measured among the environmental samples (air, surface wipe, toy wipe) and between adult and child urine, suggesting that pyrethroids redistribute in the home. The wipe samples (surface and toy) correlated with measurements of 3-PBA in adult urine but not in child urine. In addition, although highly significant correlations were calculated for adult urine and the various environmental matrices, the plots were generally very steep or very shallow, indicating that the method detection limits or background concentrations in one of the two media are limiting. This could also be suggestive of limited dose/response-type relationships. It is also important to remember that the urinary 3-PBA concentrations reflect exposure to all of the pyrethroids and not just to the target pesticide used in the correlations analyses. A significant contribution of non applied pesticides to the urinary concentrations of 3-PBA could mask any relationships between environmental and urinary concentrations. The fact that strong correlations exist between adult urine and child urine in the same home suggests a commonality of exposure routes among adults and children.
A statistical evaluation of the detection of the applied pesticides measured after their application was not as clear as expected. The abundance of nonsignificant before/after relationships suggests that the pesticides are commonly present and that their concentrations are quite variable; application does not perturb the levels to the extent that the difference is greater than the “noise.” It is also possible that very small amounts of the pesticide were applied, thus providing concentrations not measurable in the particular matrix.
Urine Data Analyses
Comparison of Hydrolyzed and Unhydrolyzed Urine Analysis Results. A key consideration in the measurement of many excreted metabolites in urine is whether the excreted form is present as a sulfate or glucuronide conjugate or as the unconjugated metabolite. Failure to measure the conjugated fraction would lead to underestimation of the urinary concentrations and, thus, of the actual exposure. This possibility of underestimation was tested for the pyrethroids by conducting analysis of urine directly (unhydrolyzed) and after deconjugation. The pre- and post-hydrolysis analysis results for 3-PBA in selected adult urine samples showed that the hydrolysis did not release additional analyte from the sample matrix.
Correlation Between Adult/Child 3-PBA Ratio and Child’s Age. Excluding imputed zero values, but including all time points in order to have sufficient data for a meaningful analysis, we computed the ratio of 3-PBA in adults to that in children, in the same home, for each home and time point. The ages of the children in this study ranged from 11 months to 30 months, with 24 months being, by far, the predominant age. The Spearman correlation coefficient for 30 observations was found to be 0.216 with a p-value of 0.253, indicating no significant relationship between the adult/child ratio and the age of the child. Assuming that the metabolism of the pyrethroids is constant over time in the adult, these data indicate that even the youngest children in this study were able to metabolize and excrete pyrethroids. Thus, it appears that children are not placed at elevated risk due solely to metabolic immaturity.
There does not appear to be any significant relationship between adult/child 3-PBA ratio and time (i.e., all slopes were found to be profoundly not significantly different from zero). This analysis was also performed using data from samples collected during the first week of sampling. The results indicate that there is no significant short-term or long-term difference in the adult/child relationships. Analysis of variance in the adult/child ratio clearly indicated that no significant difference exists among homes (p = 0.7963). This analysis was repeated, including only points from the first 7 days, and resulted in a comparable p-value of 0.8645. Overall (all homes and time points), the median ratio was 0.90 and the mean was 2.09, with a standard deviation of 3.60. A single value of 16.8 was largely responsible for the skew in the data. These results also provide no evidence for an age-dependent excretion across all homes. The variability within homes masks any variability between homes.
Correlations Between Adult and Child Concentrations for 3-PBA, DCCA, and DBCA. In order to examine relationships between urine results and results from environmental samples, the following table was constructed to provide a “bridge” between the parent analytes and their metabolites in human urine. Table 5 shows that multiple parent compounds may give rise to a particular metabolite.
Table 5. Parent Pesticides and Their Human Metabolites.
Metabolite |
Parent 1 |
Parent 2 |
Parent 3 |
Parent 4 |
Parent 5 |
Parent 6 |
3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid (DCCA) |
Cypermethrin |
Permethrin |
Cyfluthrin |
|||
cis-3-(2,2-dibromovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid (DBCA) |
Deltamethrin |
|||||
3-Phenoxybenzoic acid |
Cypermethrin |
Deltamethrin |
L-Cyhalothrin |
Permethrin |
cis-Permethrin |
trans-Permethrin |
In an evaluation of the general and more specific pyrethroid metabolites, without correcting for creatinine concentration, significant correlations were calculated for adult 3-PBA with child 3-PBA, adult 3-PBA with adult DCCA, adult 3-PBA with adult DBCA, and child 3-PBA with adult DCCA. The correlation of child 3-PBA with adult DCCA has very few data points and so is suspect. These data suggest that exposure of adults occurred to parent pyrethroids that gave rise to both the general (3-PBA) and specific (DCCA, DBCA) metabolites, which is consistent with the known applications and the measured presence of the parent compounds in the environmental media. With creatinine correction, only the relationship between adult 3-PBA and adult DCCA remained significant at the 0.05 level.
A quantitative evaluation of the adult/child 3-PBA concentration ratios with and without correction for creatinine concentrations showed that the concentration ratios did not overlap with 0 (log 0 = 1) when all observations were included and for those samples from home 007. The ratios were less than 1, suggesting that the concentrations of 3-PBA might be higher in adult urine than in child urine.
Regression of Adult Versus Child Concentrations for 3-PBA. In order to confirm and better define the magnitude of the difference between adult and child urinary 3-PBA concentrations, the data were subjected to linear regression analysis. The regression of the adult 3-PBA concentrations in urine versus that of the child concentrations was performed excluding imputed zero values but including all time points. Equivalent regression was performed for the creatinine-corrected concentrations. The results showed that only when the regression was performed across all homes/participants was the slope different from zero at a significance level of 0.05. The slope of the line showed that a 1 -unit change in child urine concentration (independent variable) results in a 2.3- unit change in adult urine concentration (dependent variable) when values are not corrected for creatinine, or in a 1.1- unit change when corrected for creatinine concentrations. This is consistent with the data in Table 4 that showed adult 3-PBA concentrations were higher. In other words, in the same environment, the 3-PBA concentrations in child urine were approximately one half those in adults.
Although the food samples were not analyzed, the consistency of the adult/child 3-PBA ratios suggests stable relative exposures over time in the home. Given the differences in the foods consumed by adults and children, consistent excretion rates of adults and children suggest that stable, consistent residues exist in the foods or that pesticide-containing dust contaminates all foods to the same extent. These data do not suggest that children’s unique behaviors result in disproportionately higher exposures to pyrethroids in the indoor environment than adults’.
References:
Adgate JL, Clayton CA, Quackenboss JJ, Thomas KW, Whitmore RW. Measurement of multi-pollutant and pathway exposures in a probability-based sample of children: practical strategies for effective field studies. Journal of Exposure Analysis and Environmental Epidemiology 2000;10(6 Pt 2):650-661.
Friedrich C, Becker K, Hoffmann G, Hoffmann K, Krause C, Nollke P, Schulz C, Schwabe R, Seiwert M. Pyrethroids in house dust of the German housing population: results of two nationwide cross-sectional studies. Gesundheitswesen 1998;60(2):95-101.
Hu Y, Beach J, Raymer J, Gardner M. Using disposable diaper to collect urine samples from young children for pyrethroid pesticide studies. Journal of Exposure Analysis and Environmental Epidemiology 2004;14(5):378.
Leidy R, Wright C, Dupree J. Exposure levels to indoor pesticides. In: Racke KD, Leslie AR, eds. Pesticides in UrbanEnvironments:Fate and Significance. Washington, DC: American Chemical Society, 1993.
Miyamoto J, Kaneke H, Tsuji R, Okuno Y. Pyrethroids, nerve poisons: how their risks to human health should be assessed. Toxicology Letters 1995;82/83:933-940.
Journal Articles on this Report : 4 Displayed | Download in RIS Format
Other project views: | All 9 publications | 4 publications in selected types | All 4 journal articles |
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Hu Y, Beach J, Raymer J, Gardner M. Disposable diaper to collect urine samples from young children for pyrethroid pesticide studies. Journal of Exposure Analysis and Environmental Epidemiology 2004;14(5):378-384. |
R829397 (2002) R829397 (2003) R829397 (2004) R829397 (Final) |
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Walse SS, Shimizu KD, Ferry JL. Surface-catalyzed transformations of aqueous endosulfan. Environmental Science & Technology 2002;36(22):4846-4853. |
R829397 (Final) R827397 (2002) R827397 (Final) |
not available |
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Walse SS, Scott GI, Ferry JL. Stereoselective degradation of aqueous endosulfan in modular estuarine mesocosms: formation of endosulfan gamma-hydroxycarboxylate. Journal of Environmental Monitoring 2003;5(3):373-379. |
R829397 (Final) R827397 (Final) |
not available |
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Walse SS, Morgan SL, Kong L, Ferry JL. Role of dissolved organic matter, nitrate, and bicarbonate in the photolysis of aqueous fipronil. Environmental Science & Technology 2004;38(14):3908-3915. |
R829397 (Final) R827397 (Final) |
not available |
Supplemental Keywords:
pyrethroid pesticides, children, longitudinal, disposable diapers, exposure modeling,, RFA, Health, Scientific Discipline, 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 assessmentProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.
Project Research Results
- 2005 Progress Report
- 2004 Progress Report
- 2003 Progress Report
- 2002 Progress Report
- Original Abstract
4 journal articles for this project