Grantee Research Project Results
2024 Progress Report: Developmental, behavioral & environmental determinants of infant dust ingestion
EPA Grant Number: R840202Title: Developmental, behavioral & environmental determinants of infant dust ingestion
Investigators: Adolph, Karen E , Boor, Brandon Emil , Claxton, Laura J , Laskin, Alexander
Institution: New York University , Purdue University
EPA Project Officer: Hahn, Intaek
Project Period: September 1, 2021 through May 10, 2025
Project Period Covered by this Report: September 1, 2023 through August 31,2024
Project Amount: $1,336,404
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:
This project will elucidate determinants of indoor dust ingestion in 6- to 24-month-old infants (age range for major postural and locomotor milestones). Our 5 specific objectives are to test: (1) whether the frequency and characteristics of indoor mouthing events change with age and motor development stage for different micro-environments; (2) how home characteristics and demographic factors affect indoor dust mass loading and dust toxicant concentration; (3) how dust transfer between surfaces is influenced by dust properties, surface features, and contact dynamics; and (4) contributions of developmental, behavioral, and socio-environmental factors to dust and toxicant-resolved dust ingestion rates. In addition, the project will (5) create a shared corpus of video, dust, toxicant, and ingestion rate data to increase scientific transparency and speed progress through data reuse by the broader exposure science community.
Progress Summary:
From September 2023 to August 2024, we made progress toward our 5 objectives as follows:
(Objective 1): To test change in mouthing events across age and motor development, we collected video behavioral data of 1 hour of infant-caregiver (6 to 24 months) natural activity in the home. In this funding year, we realized we could not recruit 12 12-month-old walkers at each site because too few infants are walking by 12 months (i.e., age at walk onset appears to have increased). Further, we realized it would be extremely difficult to recruit 12 6-month-old presitters and 12 6-month-old sitters, and 12 9-month-old precrawlers and 12 9-month-old crawlers per site due to time constraints. Thus, we determined the best course of action is to collect 12 infants at each age group at each site, regardless of posture and locomotor status for a total of 84 infants per site. By August 31, 2024, we conducted 160 of the planned 168 home visits (141 passed quality assurance). By August, we completed behavioral annotations on 80 files.
(Objective 2) To test effects of home environment and demographics on dust mass loadings and toxicant concentrations, we conducted home video tours. We video recorded cleaning products and floor cleaning equipment in each room. We administered a parent-report questionnaire about the home environment, indoor and outdoor sources of dust, the frequency and type of surface cleaning/vacuuming, ventilation and filtration methods, and shoe track-in potential.
We collected floor dust samples from 2-3 sites/per home using handheld vacuums, nylon dust collection socks, anti-static aluminum nozzles, and steel stencils. We sieved and separated the floor dust from 260 samples and entered the data into our database of un-sieved and sieved floor dust mass loadings. We determined floor dust mass, volume, and number of size distributions using a laser diffraction particle sizer. We developed a procedure to determine the bulk dust index of refraction, apparent density, and morphological features. We developed and validated quality assurance plans for the dust gravimetric, laser diffraction analysis, and morphological analysis.
We conducted chemical characterization experiments on 108 dust samples to investigate components of toxicological concern, including environmental persistent free radicals (EPFRs), heavy toxic metals (HTMs), and persistent organic pollutants (POPs). We developed and implemented experimental protocols to quantify HTMs and EPFR species on all samples. Based on mass loading data, approximately 20% of the samples were selected for non-targeted screening of POPs to inform subsequent targeted analyses of specific toxicants.
(Objective 3) To simulate dust transfer from floor-to-hand and hand-to-mouth, we devised a protocol to measure infant hand size and built an environmental chamber to test dust transfer. We created a clean air supply system to provide dust-free air to the chamber at variable volumetric airflow rates and relative humidities. The chamber houses a robotic contact simulator, floor surface samples with simulated dust deposits, and instrumentation to measure resuspended dust size distributions in the air. We designed, built, and evaluated a novel robotic contact simulator to simulate infant hand-to-floor contacts based on infant crawling data. We created an experimental matrix for experiments in the environmental chamber to systematically evaluate how behavioral and environmental factors affect dust migration and redistribution in infants’ microenvironments.
(Objective 4) We have not begun to analyze contributions of developmental, behavioral, and socio-environmental factors to dust ingestion.
(Objective 5) To create a shared corpus of behavioral and dust data, we uploaded all the videos, questionnaires, and annotated behavioral data into a curated volume on Databrary to be openly shared with authorized investigators. We worked on a researcher-facing website.
Future Activities:
We will complete data collection, QA, and video behavioral coding. We will analyze dust mass loadings, size distributions, morphological features, and composition and concentrations (mass of toxicant per mass of indoor dust) of EPFR, HTM, and POP. We will conduct dust migration experiments in with our robotic contact simulator. We will determine size-resolved dust contact transfer and resuspension fractions associated with infant hand-to-floor contact and estimate agespecific dust ingestion and inhalation rates using a mass balance model and behavioral data. Findings will allow predictive understanding of effects of the indoor environment on potential ingestion of hazardous toxicants. We will submit a group manuscript for the special issue on children’s chemical exposures from soil and dust ingestion in JESEE in December 2024.
Journal Articles:
No journal articles submitted with this report: View all 13 publications for this projectRelevant Websites:
Progress 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.