Grantee Research Project Results
2023 Progress Report: Optimizing use of novel chemicals to assess childrens dust ingestion rates
EPA Grant Number: R840208Title: Optimizing use of novel chemicals to assess childrens dust ingestion rates
Investigators: Bennett, Deborah H. , Young, Thomas M , Kannan, Krunthachalam
Institution: University of California Davis , New York University
EPA Project Officer: Hahn, Intaek
Project Period: June 1, 2021 through May 31, 2024 (Extended to May 31, 2026)
Project Period Covered by this Report: June 1, 2023 through May 31,2024
Project Amount: $1,342,099
RFA: Estimating Childrens Soil and Dust Ingestion Rates for Exposure Science (2020) RFA Text | Recipients Lists
Research Category: Children's Health , Endocrine Disruptors , Human Health
Objective:
The goals of this project are to: (1) Develop an innovative method for determining dust ingestion rates using compounds found primarily in indoor dust rather than outdoor soil, (2a) Measure dust ingestion in children living in homes from four distinct geographic areas with differing SES, urban/rural/suburban classification, and racial/ethnic composition and an additional cohort of children with autism or developmental delays, (2b) Determine the concentrations of a broad range of target and non-target compounds in house dust to improve understanding of indoor chemical exposures as a function of demographic variables, (3) Measure seasonal and age group variation in dust ingestion rates, and (4) Develop standard procedures for the dust tracer method to support its implementation by other organizations
Progress Summary:
1. Selection of target compounds: The target list of compounds to analyze in dust was completed in the prior year of this project. Our targeted analysis panel includes 11 aromatic amines, 3 benzophenones, 4 bisphenols, 4 parabens, 3 polycyclic aromatic hydrocarbons, 13 organophosphate esters, 8 phenols, 14 phthalates, 15 fungicides, 4 herbicides, 3 neonicotinoids, 4 insecticides, 1 rodenticide, 26 other industrial compounds, approximately 30 compounds not listed above that were evaluated in a prior study of potential tracer compounds or that were found to be ubiquitous in dust, 3 drugs, 6 natural products, and 6 additional personal care ingredients.
2. Development of protocol: Protocols were developed in the first year of the study.
3. Participant recruitment: Participant recruitment and sample collection is complete. An additional 85 paired urine and dust samples were collected in the past year. For the methods development portion, in total, for 13 participant we collected a duplicate diet and skin wipe sample, and for 4 more participants we collected a skin wipe sample in addition to dust and urine. For 8 of those participants, we collected 3 urine sample so examine temporal variability.
In addition to the 17 participants aged 2-3 in Northern California in the methods development group, we recruited an additional 15 participants in this age group, bringing the total to 32. To get at seasonal variability, we collected a second sample 6 months later for 23 participants. We collected samples from 20 participants aged 6-24 months, 2 of which provided a second sample 6 months later. We collected samples from 17 participants with autism spectrum disorder (ASD). We collected samples from 20 participants age 4-5 years. To assess regional variability, we collected samples from 20 participants in Southern California.
4. Sample collection for Methods Development: As noted above, we had 13 participants complete the full method development sample collection, last year, with 4 participants also providing dust, urine, and a skin wipe sample this year. We procured a number of food samples representative of what children eat to supplement our knowledge of chemicals found in foods typical in the diet of children at this age.
5. Collection of questionnaire data: We have collected data from participants in a high risk autism birth cohort and from an autism case control study from over 25 participants. We will use this to identify the range of answers to determine which participants and to determine if there are differences by developmental outcome. We are additionally utilizing an existing dataset that includes more limited questions on dust ingestion but was administered to several hundred participants in a case control study of ASD, developmental delay, and typically developing children.
6. Analysis of Dust, Food, and Wipe Samples: We had 21 dust samples (4 were collected from the same house 6 months later to assess temporal variability), 17 wipe samples, and 13 solid duplicate diet samples, 7 of which included a separate liquid portion, analyzed. In addition, we had 12 representative food samples analyzed selected to contain child-oriented items, including vegetables, citrus fruit, non-organic non-citrus fruit, vegetable proteins, less processed grains, oily and salty processed grains, unprocessed lean animal protein, fatty processed animal protein, fast food, fatty food, dairy, and one sample on non-child oriented food.
Samples were analyzed for a 70 compound GC panel and a 68 compound LC platform developed to focus on finding potential tracers and measuring new compounds of potential concern. Of these compounds, 59 were measured in at least 14 of the homes, indicating widespread exposure. However, for some of the compounds a portion of the detected samples were below the Limit of Quantification (LOQ), thus only the 44 compounds with quantifiable levels in at least 13 of the homes were further considered. Of these, 20 had both 3 or more detectable wipe samples and 3 or more detectable food samples. One compound had detectable levels in 3 or more food samples. There were a number of samples detected in wipe samples but not food, and we considered compounds with up to 7 wipe samples because in part, some of these are likely to be due to dust on skin. There were 9 compounds with over 7 detectable compounds. This left the following 14 compounds under consideration. Several were not good targets based on further consideration, specifically bisphenol A and bisphenol F, traditionally used in food packaging; the combination of butyl and isobutyl paraben, traditionally used in personal care products; cholesterol, a human endogenous compound; and physcion, a component of food. The most promising compounds were 1,3-diphenylguanidine, toluene-2sulfonamide, 2-mercaptobenzothiazole, tris(2-butoxyehtyl) phosphate, and tris(2chloroisopropyl) phosphate. All of these compounds except toluene-2-sulfonamide have a known metabolite in urine, although we will try to measure it and see if it is measured. Three other compounds met the basic criteria but upon detailed inspection, did not seem to be suitable candidates, specifically, fipronil sulfone, diethylene glycol dibenzoate and 3-Buten-2-one, 3methyl-4-(2,6,6-trimethyl-2-cyclohexen-1-yl)-. We considered non-target results and did not find any other additional compounds to consider.
7. Analysis of Urine Samples: We have sent 37 urine samples to be analyzed along with 8 blinded duplicates. Samples will be analyzed for two panels, the first consisting of 1,3diphenylguanidine (DPG), 2-Mercapto benzothiazole (2-MBT), 1,3-benzothiazole (1,3-BTH) and toluene-2-sulfonamide (T2S) and the second a panel of OPEs, TCIPP and its metabolite DCIPP.
Future Activities:
We are currently analyzing the urine samples that correspond to the food samples, dust and skin wipe samples already analyzed. Then, we will impute dust ingestions rates for all the compounds for each child and then apply both the Best Tracer Method (BTM) and the Limiting Tracer Method (LTM) to evaluate candidate tracer chemicals for suitability. The combination of our targeted measurement of diverse compounds present in indoor environments with their associated metabolites will allow the first application of LTM and BTM for estimating dust ingestion rates. We will complete sample analysis for the dust and urine for the remaining sample for the list of most likely tracers.
Journal Articles:
No journal articles submitted with this report: View all 2 publications for this projectSupplemental Keywords:
indoor dust, dust Ingestion, hand-to-mouth activityProgress 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.