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Scholarly Works (6 results)

  • Article
  • Peer Reviewed
UC Irvine Previously Published Works (2020)

Background

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the serum of the general US population, and were detected in public water systems serving approximately 16.5 million US residents during 2013-2015. Low birthweight was associated with PFAS exposures in previous studies.

Methods

Birthweights for singleton births during 2013-2015 were obtained from CDC WONDER, multiply stratified by county, maternal age, race, education, smoking status, and parity. PFAS water concentrations were obtained from EPA UCMR3 database and aggregated by county. Multiple regression weighted by inverse variance was used to produce effect estimates equivalent to those that would be obtained from individual-level data on birthweight and confounders.

Results

Adjusting for stratification demographic confounders (maternal age, race, education, smoking status, and parity), we found an average change in birthweight of 0.9 g (95% confidence interval [CI] = -0.5, 2.2), -1.3 g (-1.6, -0.9), -3.8 g (-4.9, -2.7), and -3.8 g (-4.3, -3.3) per ng/L increase in the population-weighted average perfluorooctanoic acid, perfluorooctane sulfonate, perfluoroheptanoic acid, and perfluorohexane sulfonic acid in public water supplies by county, respectively. We found an average change in birthweight of -1.0 g (95% CI = -1.2, -0.8) per ng/L increase in the sum of perfluorooctanoic acid, perfluorooctane sulfonate, perfluoroheptanoic acid, and perfluorohexane sulfonic acid concentrations in public water supplies.

Conclusions

The direction and magnitude of association between PFAS and birthweight varied by PFAS chemical in this study. Conclusions are tempered by inherent limitations of the 2 public-use datasets, and by the sensitivity of our results to alternative methods such as mutual adjustment for co-exposures.
    Cover page: Per- and polyfluoroalkyl substances in drinking water and birthweight in the US
    • Article
    • Peer Reviewed
    UC Irvine Previously Published Works (2022)

    Background

    Per- and polyfluoroalkyl substances (PFAS) widely exist in the environment and human bodies. Contaminated drinking water is one of the major exposure pathways for humans. Previous studies found weak or moderate associations between PFAS and hypertensive disorders of pregnancy (HDP).

    Methods

    We obtained the number of births and counts of HDP cases for singleton births multiply stratified by county, maternal age, race, education, smoking status, and parity from CDC WONDER, and PFAS water concentrations from EPA UCMR3 data in the United States during 2013-2015. We used binomial regression on the multiply stratified HDP data to produce equal effect estimates and standard errors to those that would be derived from using individual-level data on binary HDP status and demographic covariates in logistic regression.

    Results

    After adjusting for demographic covariates, we found small but statistically significant positive associations between HDP and population-weighted average water concentrations (ng/L) of all four PFAS: Odds ratio (OR) = 1.009, 95% CI = (1.001, 1.016) per IQR increase in perfluorooctanoic acid (PFOA); 1.030, 95% CI = (1.021, 1.040) per IQR increase in perfluorooctane sulfonate (PFOS); 1.008, 95% CI = (1.005, 1.011) per IQR increase in perfluoroheptanoic acid (PFHpA); 1.007, 95% CI = (1.004, 1.010) per IQR increase in perfluorohexane sulfonic acid (PFHxS), and 1.032, 95% CI = (1.022, 1.042) per IQR increase in the sum of four PFAS. Further adjustment for coexposures reversed the effect of PFOA from positive to inverse, and attenuated the effects of PFOS and PFHxS toward the null. After drinking water to serum concentration conversions, our effect estimates for PFOA, PFOS, and PFHxS are similar to previous studies.

    Conclusions

    We found a weak positive association between the PFAS mixture and HDP, although the generalizability is subject to inherent limitations of the public-available datasets.
      Cover page: Per- and polyfluoroalkyl substances in drinking water and hypertensive disorders of pregnancy in the United States during 2013–2015
      • Article
      • Peer Reviewed
      UC Irvine Previously Published Works (2021)

      Background

      Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the serum of the general US population. Food, drinking water, consumer products, dust, and air have been assessed as PFAS exposure sources for humans. The effects of various types of carpeting on serum PFAS concentrations have been less studied, despite the known use of PFAS in stain-resistant carpet treatments.

      Objective

      This study aimed to examine the associations between serum PFAS concentrations and type of residential flooring among the general US population aged 12 years and older using the 2005-2006 National Health and Nutrition Examination Survey (NHANES).

      Methods

      We used multiple linear regressions adjusted for complex survey design and relevant covariates to analyze the relations between serum PFAS concentrations and type of floor covering (smooth surface, low pile carpet, medium to high pile carpet, and combination of carpet and smooth surface), as well as other potential exposure factors. We used multiple imputation to address missing values.

      Results

      We found significantly higher serum concentrations of perfluorohexane sulfonic acid (PFHxS) and 2-(N-methyl-perfluorooctane sulfonamido) acetic acid (MeFOSAA) in US residents residing in homes with low pile carpeting compared with those residing in homes with smooth surface. We concluded that among US residents aged 12 years and older residing in homes with low pile carpeting in the home in 2005-2006, on average 24% and 19% of the PFHxS and MeFOSAA body burdens, respectively, could be attributed to carpeting. We found associations between other types of floor covering (medium to high pile carpet, combination of carpet and smooth surface) and some PFAS concentrations compared with the smooth surface, but these results were less consistent and generally not statistically significant. Additionally, a group Wald Chi-squared test showed a significant result for PFOS, indicating different contributions of various types of flooring to PFOS serum concentration.

      Significance

      Our results are representative of the general US population at the time of the survey, and potentially informative regarding ongoing PFAS exposure from a variety of sources including carpeting.
        Cover page: Household low pile carpet usage was associated with increased serum PFAS concentrations in 2005–2006
        • Thesis
        • Peer Reviewed
        UC Irvine Electronic Theses and Dissertations (2022)

        PFAS and air pollution are two groups of modifiable risk factors in the environment. According to the National Health and Nutrition Examination Survey, PFAS are ubiquitous in the serum of the general US population. Contaminated seafood and drinking water, packaged fast food, stain-resistant or water-repellant consumer products, dust, and air are the major exposure routes to humans. In addition, ambient air pollution remains the greatest environmental risk factor and is associated with 100,000-200,000 deaths annually in the US, although the air quality in the US has dramatically improved over the past few decades compared to its historical levels and other countries in the world. Infants, pregnant women, and elderly people are three typical populations that are especially susceptible to these environmental pollutants. In Chapter 2, we examined the associations between serum PFAS concentrations and type of residential flooring among the general US population aged 12 years and older using the 2005-2006 NHANES survey data. We concluded that low pile carpeting was associated with increased serum concentrations of PFHxS and MeFOSAA in the general US population. In Chapters 3 and 4, we conducted two nationwide studies investigating the impacts of PFAS detected in drinking water on birthweight and HDP status, respectively. We used county-level aggregated PFAS data from EPA UCMR3 and county-level multiple-stratified birth/pregnancy data from CDC WONDER. We concluded that the PFAS mixture found in drinking water may contribute to low birthweight and hypertensive disorder of pregnancy in the US. In Chapters 5 and 6, we further conducted two subgroup analyses using data from the C8 and IHS projects, respectively, focusing on two population subgroups with significantly higher environmental exposure to PFOA and O3 in the US due to local industries. Our studies suggest PFOA is moderately associated with preeclampsia in the C8 project and O3 is associated with a higher risk of dementia in American Indians. Future efforts to reduce exposure to PFAS and air pollution might help lower risks of low birthweight, hypertensive disorders of pregnancy/preeclampsia, and dementia in the US.

          Cover page: Understanding the Health Impacts of Per- and Polyfluoroalkyl Substances (PFAS) and Air Pollution on Susceptible Populations in the US
          • Article
          • Peer Reviewed
          UC Irvine Previously Published Works (2022)
            Cover page: Air pollution and dementia using longitudinal electronic health record data from the Indian Health Service
            • Article
            • Peer Reviewed
            UC Irvine Previously Published Works (2024)
            (1) Background: American Indians are disproportionately affected by air pollution, an important risk factor for dementia. However, few studies have investigated the effects of air pollution on the risk of dementia among American Indians. (2) Methods: This retrospective cohort study included a total of 26,871 American Indians who were 55+ years old in 2007, with an average follow-up of 3.67 years. County-level average air pollution data were downloaded from land-use regression models. All-cause dementia was identified using ICD-9 diagnostic codes from the Indian Health Service’s (IHS) National Data Warehouse and related administrative databases. Cox models were employed to examine the association of air pollution with dementia incidence, adjusting for co-exposures and potential confounders. (3) Results: The average PM2.5 levels in the IHS counties were lower than those in all US counties, while the mean O3 levels in the IHS counties were higher than the US counties. Multivariable Cox regressions revealed a positive association between dementia and county-level O3 with a hazard ratio of 1.24 (95% CI: 1.02–1.50) per 1 ppb standardized O3. PM2.5 and NO2 were not associated with dementia risk after adjusting for all covariates. (4) Conclusions: O3 is associated with a higher risk of dementia among American Indians.
              Cover page: Potential Effects of Long-Term Exposure to Air Pollution on Dementia: A Longitudinal Analysis in American Indians Aged 55 Years and Older
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