Final Report: Residential Exposure of Young Children to SVOCs

EPA Grant Number: R835642
Title: Residential Exposure of Young Children to SVOCs
Investigators: Stapleton, Heather , Webster, Thomas F. , Ferguson, P. Lee
Institution: Duke University , Boston University
EPA Project Officer: Aja, Hayley
Project Period: September 1, 2014 through August 31, 2017 (Extended to August 31, 2018)
Project Amount: $900,000
RFA: New Methods in 21st Century Exposure Science (2013) RFA Text |  Recipients Lists
Research Category: Chemical Safety for Sustainability

Objective:

The goals of this project are to: 1) Characterize SVOC sources in the home that may be potential sources of SVOCs (and other chemical additives) to the indoor environment (e.g. furniture, vinyl flooring, electronics, insulation, etc). 2) Characterize and quantify residential exposure of young children to SVOCs using targeted and non-targeted methods on hand wipe samples, and determine how closely these measurements correlate with levels measured in paired samples of serum, urine, indoor air, and house dust from 50 children between the ages of 24-48 months of age; 3) Identify sources of variability in hand wipe measurements such as hand washing, lotions, etc.; 4) Examine the patterns of co-exposure to multiple SVOCs (an important issue in the assessment of chemical mixtures); and 5) Compare our empirical results for SVOCs with predictions from indoor models.

Summary/Accomplishments (Outputs/Outcomes):

We conducted a cross-sectional study to examine childrens exposure to semi-volatile organic chemicals (SVOCs) in the home environment, and examine potential sources of exposure in the home. To support this research study, we invited families that had previously been enrolled in a pregnancy cohort at Duke University to enroll in our new study. To be eligible, families had to live within 50 miles of Durham, NC and their children had to be 6 years of age or younger. From August 2014 through May 2016, 188 families, including 203 children, several of which were siblings, were recruited to be part of the TESIE cohort (Toddlers Exposure to Semi-volatile organic chemicals in the Indoor Environment).

To participate in the study all families signed an informed consent form. A research team visited the homes to collect samples, including blood (collected by a research phlebotomist) and handwipe samples from the children. Kits were left with the parents to collect urine samples (3 samples collected over 48 hours), which were later picked up by the study team. During the home visits, we also deployed passive air samplers in 50 of the homes, and in all homes we collected house dust, surface wipes (of TVs, vinyl floor, and upholstery), and samples of polyurethane foam (PUF) from furniture cushions (for analysis of flame retardant treatments). And for a sub-set of the children we also asked them to wear a pre-cleaned silicone wristbands for 5 days in the home to serve as a passive sampler. The wristbands were picked up from the family the following week. All families were compensated for their time with a gift card and a collection of childrens books.

Levels of exposure for many of the SVOCs appear to be higher in the TESIE cohort compared to similarly aged children measured in the NHANES study (Hoffman et al. 2018). Our analyses indicate that some of these differences in exposure (e.g. phthalates and chlorophenols) are significantly associated with lower socioeconomic status. We also observed significant seasonal variation in several of the urinary SVOC biomarkers of exposure, including the organophosphate esters, metabolites of sunscreen, and some phthalate plasticizers. This is important given that many epidemiological studies do not account for season of collection in their analyses. Many of the SVOCs displayed significant correlations with each other, although not all. Of interest is the fact that some children often had high exposure to a large number of chemicals while other children did not. By analyzing these patterns in more detail, we hope to determine if particular patterns of SVOC exposure are associated with product use or behavior.

In addition to the data described above we also collected data on SVOCs from passive air samplers (50 of the 188 homes), house dust, hand wipes, and polyurethane foam (PUF). Due to the nature of the passive sampler design, only the more volatile (i.e. non-particle bound) SVOCs were detected in the air samplers. Our analyses suggest that there was a suggestive association between several of the OPEs and their urinary metabolites, but none reached statistical significance. Childrens exposure to OPEs based on measurements in the handwipes and dust are now published (Phillips et al. 2018) and a similar study focusing on phthalate exposures in children is currently under review (Hammel et al. 2019). In both studies we found that the handwipes were a better predictor of childrens exposure rather than estimating exposure based on levels measured in dust, and likely reflect exposures from multiple micro-environments.

A primary goal of this study was to evaluate links between chemical applications used in consumer products and building materials with childrens exposure. In this study we focused on flame retardants, phthalate plasticizers and one pesticide. Our analysis of the PUF samples collected from sofas in the TESIE homes identified a suite of different flame retardant applications that are similar to the flame retardants identified in our previous studies. To examine the potential influence of these chemical applications in sofas on childrens exposure, we examined the differences in childrens biomarkers of flame retardant exposures based on whether the flame retardant was present or absent in the sofa from their home. For example, we found that PentaBDE, a commercial flame retardant mixture, was present in sofas from several of the TESIE homes (n=6). Children living in these homes had significantly higher levels (7X higher; p<0.001) of serum PBDEs in their blood compared to children living in homes that did not have PentaBDE in their sofa. We also examine childrens exposure to phthalates based on the use of specific personal care products (collected using a survey administered during the home visit) and the presence of vinyl flooring in the home. We did not find any associations with personal care products based on the survey data; however, the amount and type of flooring in the home was associated with exposure. During the home visit the dimensions of all rooms containing vinyl were recorded by the researchers. Our study found that children living in homes in which 100% of the flooring was vinyl had significantly higher exposure to several phthalates, and in particular benzyl butyl phthalate. Children living in homes in which all the flooring was vinyl had urinary metabolites of benzyl butyl phthalate that were 16X higher (p<0.001) than children living in homes with no vinyl flooring. It was also interesting to note that the homes with 100% vinyl flooring were all public housing units, suggesting that construction materials used in public housing may be contributing to elevated exposures to phthalates. These results have been written into a manuscript that is currently undergoing review (Hammel et al. 2019). Lastly, we also measured several strobilurin fungicides in the dust samples as we became aware of a new use for one fungicide, azoxystrobin, in wallboard that began around 2000. We analyzed the house dust and handwipe samples four different strobilurin fungicides, but azoxystrobin was found most frequently and in the highest concentrations. Unfortunately, there are no established biomarkers of exposure for azoxystrobin, and thus we had no measure of internal dose. To determine if the dust levels may be associated with chemical applications in drywall, we collected and analyzed 12 drywall samples from home improvement stores in six different states across the US, including North Carolina. Azoxystrobin was detected and measured in the paper of the drywall in all samples, suggesting it could be a source to indoor dust. We did conduct statistical analyses to determine if the dust concentrations of azoxystrobin were correlated with year of construction of the home; however, results were not significant. We did not collect information on renovations that occurred in homes, which may lead to a bias in understanding the introduction of recently purchased wallboard containing these fungicides, but future studies may want to investigate this further. These results are included in a manuscript that is also undergoing peer review (Cooper et al. 2019)

Lastly, we analyzed the dust samples using non-targeted high-resolution mass spectrometry techniques to characterize the samples for other chemicals. Over 10,000 chemicals were present in most of the dust samples, and a few dozen chemicals were detected in paired samples of dust and handwipes, including the pesticides fipronil and imidacloprid, and a number of different surfactants including nonylphenol and octylphenol ethyoxylates used in laundry detergents, shampoos, etc. These results highlight the utility of using non-targeted analyses to increase our understanding of individual exposures. We are currently conducting statistical analyses on these datasets to examine mixtures and patterns of co-exposure in the home with the hope of evaluating links with home characteristics (e.g. age of home, carpeting) and product use.

Conclusions:

This research study demonstrates that children are receiving chronic exposure to mixtures of SVOCs, and a majority of this exposure appears to originate in the home environment. Interestingly, exposures to many of the SVOCs were significantly correlated, and displayed seasonal variation. Both of these are important considerations for environmental epidemiology studies that examine associations between exposure to SVOCs and health outcomes, particularly when used in a cross sectional design. This highlights the importance of considering confounding variables, such as season and co-exposures, in statistical models.


Journal Articles on this Report : 7 Displayed | Download in RIS Format

Other project views: All 15 publications 11 publications in selected types All 11 journal articles
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Journal Article Ceballos D, Young A, Allen J, Specht A, Nguyen V, Craig J, Miller M, Webster T. Exposures in nail salons to trace elements in nail polish from impurities or pigment ingredients – A pilot study,. International Journal of Hygiene and Environmental Health, 2021;232:113687. R835642 (Final)
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  • Journal Article Fedorchak NJ, Lyer N, Ashton RS. Bioengineering tissue morphogenesis and function in human neural organoids. Seminars in Cell & Developmental Biology 2021;111:52-59. R835642 (Final)
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  • Journal Article Gardner C, Hoffman K, Stapleton H, Gunsch C. Exposures to Semivolatile Organic Compounds in Indoor Environments and Associations with the Gut Microbiomes of Children. Environmental Science Technology Letters 2020;8(1):73-79. R835642 (Final)
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  • Journal Article Hall S, Patton S, Petreas M, Zhang S, Phillips A, Hoffman K, Stapleton H. Per- and Polyfluoroalkyl Substances in Dust Collected from Residential Homes and Fire Stations in North America. Environmental Science & Technology 2020;54(22):14558-14567 R835642 (Final)
    not available
    Journal Article Hammel S, Hoffman K, Phillips A, Levasseur J, Lorenzo A, Webster T, Stapleton H. Comparing the Use of Silicone Wristbands, Hand Wipes, And Dust to Evaluate Children's Exposure to Flame Retardants and Plasticizers. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020;54(7):4484-4494. R835642 (Final)
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  • Journal Article Levasseur J, Hammel S, Hoffman K, Phillips A, Zhang S, Ye X, Calafat A, Webster T, Stapleton H. Young children's exposure to phenols in the home: Associations between house dust, hand wipes, silicone wristbands, and urinary biomarkers. Environmental International 2021;147(106317) R835642 (Final)
    not available
    Journal Article Nicholas TP, Kavanaugh T, Faustman EM, Altermeier WA. The Effects of Gene × Environment Interactions on Silver Nanoparticle Toxicity in the Respiratory System. Chemical Research in Toxicology 2019:32(6); 952-968. R835642 (Final)
    R835738 (Final)
    R835738C001 (2018)
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  • Supplemental Keywords:

    Children's Exposure, SVOCs, indoor environment, wristbands, hand wipes, flame retardants, product wipes

    Relevant Websites:

    Toddlers' Exposure to SVOCs in the Indoor Environment Exit

    Progress and Final Reports:

    Original Abstract
  • 2015 Progress Report
  • 2016 Progress Report
  • 2017 Progress Report