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Open Access Publications from the University of California

Scholarly Works (79 results)

  • Thesis
  • Peer Reviewed
UC Irvine Electronic Theses and Dissertations (2022)

Perfluoro-n-octanoic acid (PFOA) and Perfluoro-1-octanesulfonate (PFOS) are ubiquitous and highly stable toxins in our environment. Animal and epidemiological research studies have begun to shed light on the toxicological profile and health effects of PFOA/S, including their impacts on respiratory function. Asthma is one of the health effects that has been linked to PFOA/S exposure. In this study, we explored the association between PFOA/S in drinking water and asthma emergency department (ED) visits per 10,000 in Orange (OC) and LA counties (LAC). These studies were conducted at the population level using data sets containing drinking water concentrations of PFOA/S and number of asthma ED visits within the ZIP Codes of the 2 counties. PFOA/S concentrations in drinking water for LAC and OC water districts from 2013-2015 was obtained from the Third Unregulated Contaminant Monitoring Rule dataset. We conducted geographical analysis using ArcGIS by quantitatively mapping PFOA/S drinking water levels and asthma ED visits by ZIP Code. We performed statistical analysis using linear as well as non-linear regression methods to determine if PFOA/S drinking water levels were associated with asthma ED. These statistical analyses controlled for various potential confounders of this relationship — race, education, household income, air quality (diesel, pm2.5). Mapping and statistical analysis did not reveal a direct relationship between PFOA/S drinking water levels and rates of asthma ED visits.

    Cover page: Association between PFOA/PFOS Drinking Water Exposures and Asthma ED Visits
    • Thesis
    • Peer Reviewed
    UC Irvine Electronic Theses and Dissertations (2019)

    While wide-scale public health prevention efforts have significantly decreased national teen birth rates, disparities in teen births persist at local levels. The aims of this dissertation were to conduct a spatial analysis of maternal teen birth status in all births surrounding the New Bedford Harbor Superfund site (MA, USA) over two distinct time periods (1992-1998 and 2002-2008); to assess whether joint exposures of modeled prenatal chemical exposures elevate risk of subsequent teen birth in infant females born between 1992-1998 near NBH (MA Birth Record Cohort); and, to ascertain whether similar or different combinations of joint exposures affect subsequent teen birth in New Bedford Cohort (NBC) females. The spatial analyses in Chapter 2 demonstrated a statistically significant hot spot of elevated risk of teen birth west of the NBH only for the later time period (2002-2008). Chapter 3 employed predictive exposure models built from measured biomarkers in the NBC to estimate prenatal exposures for cord serum DDE, cord serum HCB, maternal hair Hg, cord blood Pb, and cord serum PCB4 for all births in four towns surrounding the NBH from 1992-1998. Epidemiological models, using an innovative extension of generalized additive models, for both MBRC (Chapter 3) and the NBC (Chapter 4) demonstrated higher risk for subsequent teen birth across low levels of DDE and higher levels of the remaining chemical exposures. In Chapter 4, the apparent protective effect of DDE persisted even after adjustment for maternal dietary factors. Although this research has its limitations, it provides a novel approach to analyzing mixtures of chemical and non-chemical exposures and makes a significant contribution to the literature on the effects of joint chemical exposures on maternal, child, and adolescent health.

      Cover page: Prenatal Environmental Exposures and Teen Births Around the New Bedford Harbor Superfund Site (USA)
      • Thesis
      • Peer Reviewed
      UC Irvine Electronic Theses and Dissertations (2017)

      Particulate matter with a diameter of 2.5 microns or less (PM2.5), a surrogate estimate of traffic-related air pollution, is widespread and a risk to public health. In-utero exposures to PM2.5 may increase risk of birth defects, the leading cause of infant death during the first year of life in the United States, while early life exposures may increase risk of morbidities, such as bronchiolitis, the leading cause of infant hospitalizations, or otitis media (OM), the most common childhood infection. Infants may be more susceptible to negative PM2.5 effects because they are more likely to be active, breathe more air per pound of body mass, and are still developing. The effects of in utero and early life PM2.5 exposure on the risk of birth defects and infant bronchiolitis and OM are assessed among all births from 2001-2009 using the Pregnancy Early Life Longitudinal Data System (PELL), a Massachusetts birth cohort that has been linked to all subsequent records of clinical encounter. PM2.5 exposure models were based on data from satellite remote sensing, which provide extensive spatial coverage throughout Massachusetts. Findings suggest in utero PM2.5 exposure during specific critical windows of exposure may be associated with risk of specific cardiac defects. Acute early life PM2.5 exposure was associated with risk of infant bronchiolitis and OM clinical encounters, especially among preterm infants. Investigations of chronic PM2.5 exposure indicate null associations with infant bronchiolitis and OM clinical encounters, even after rigorous control for confounding.

        Cover page: Effects of In Utero and Early Life PM2.5 Exposure on Disease Risk Among Infants and Young Children
        • Article
        • Peer Reviewed
        UC Irvine Previously Published Works (2023)
        Previous studies have suggested that traffic-related air pollution is associated with adverse fertility outcomes, such as reduced fecundability and subfertility. The purpose of this research is to investigate if PM2.5 exposure prior to conception or traffic-related exposures (traffic density and distance to nearest major roadway) at birth address is associated with fertility-assisted births. We obtained all live and still births from the Massachusetts state birth registry with an estimated conception date between January 2002 through December 2008. All births requiring fertility drugs or assisted reproductive technology were identified as cases. We randomly selected 2000 infants conceived each year to serve as a common control group. PM2.5 exposure was assessed using 4 km spatial satellite remote sensing, meteorological and land use spatiotemporal models at geocoded birth addresses for the year prior to conception. The mean PM2.5 level was 9.81 µg m-3 (standard deviation = 1.70 µg m-3), with a maximum of 14.27 µg m-3. We calculated crude and adjusted fertility treatment odds ratios (ORs) and 95% confidence intervals (CI) per interquartile range of 1.72 µg m-3 increase in PM2.5 exposure. Our final analyses included 10 748 fertility-assisted births and 12 225 controls. After adjusting for parental age, marital status, race, maternal education, insurance status, parity, and year of birth, average PM2.5 exposure during the year prior to conception was weakly associated with fertility treatment (OR: 1.01; 95% CI: 0.97, 1.05). Fertility-assisted births were inversely associated with traffic density (highest quartile compared to lowest quartile, OR: 0.92; 95% CI: 0.83, 1.02) and positively associated with distance from major roadway (OR per 100 m: 1.01; 95% CI: 1.00, 1.02) in adjusted analyses. We did not find strong evidence to support an adverse relationship between traffic-related air pollution exposure and fertility-assisted births.
          Cover page: Association between traffic-related air pollution exposure and fertility-assisted births
          • Thesis
          • Peer Reviewed
          UC Irvine Electronic Theses and Dissertations (2020)

          Not only is ovarian cancer the 5th leading cause of cancer death in American women, it is also the deadliest of the gynecological cancers and among the malignancies of which disparities in care and outcomes in underserved populations are prominent. The aims of this dissertation were to investigate the association between residential geographic location and ovarian cancer outcomes, while considering the relationship between race and socioeconomic factors. Incident ovarian cancer cases were ascertained from the California Cancer Registry for women diagnosed between 1996 and 2014. Adherence to the National Comprehensive Cancer Network (NCCN) guidelines for treatment was used as a binary measure of receipt of quality care. Two geographic variables assessing access to care were also considered: distance traveled to receive care and the proximity of the closest high-quality-of-care (QOC) hospital. Spatial analyses using generalized additive models found geographic location to be an independent predictor of NCCN treatment adherence for women in California. Women of lower socioeconomic status and minority race/ethnicity were found to receive less quality care and to be disproportionately affected by geographic barriers. While spatial analyses identified location as an independent predictor of ovarian cancer survival, location no longer had an effect on survival after adjusting for sociodemographic variables, receipt of NCCN care, and geographic access to care. To assess the impact of air pollution, ozone, particulate matter with diameter less than 2.5 microns (PM2.5), and nitrogen dioxide (NO2) data was extracted from California Air Resources Board’s (CARB) online database, Air Quality and Meteorological Information System (AQMIS). Monthly averages of each pollutant were linked to women’s residential address and calculated over their survival period. Distance to nearest major roadway was determined to account for local traffic. The analyses are suggestive of a potential association between ovarian cancer survival and NO2 and PM2.5 exposure in California, independent of sociodemographic and treatment factors. The impact of these pollutants was greatest among women in early stages. Null associations were observed for ozone and distance to road when examined alone, although they had marginal effects when examining them in multipollutant models.

            Cover page: Geographic Location and its Contribution to Disparities in Ovarian Cancer Treatment and Survival in California
            • Article
            • Peer Reviewed
            UC Irvine Previously Published Works (2013)

            Objectives

            Geographic Information Systems (GIS) is a powerful tool for assessing exposure in epidemiologic studies. We used GIS to determine the geographic extent of contamination by perfluorooctanoic acid, C8 (PFOA) that was released into the environment from the DuPont Washington Works Facility located in Parkersburg, West Virginia.

            Methods

            Paper maps of pipe distribution networks were provided by six local public water districts participating in the community cross-sectional survey, the C8 Health Project. Residential histories were also collected in the survey and geocoded. We integrated the pipe networks and geocoded addresses to determine which addresses were serviced by one of the participating water districts. The GIS-based water district assignment was then compared to the participants' self-reported source of public drinking water.

            Results

            There were a total of 151,871 addresses provided by the 48,800 participants of the C8 Health Project that consented to geocoding. We were able to successfully geocode 139,067 (91.6%) addresses, and of these, 118,209 (85.0%) self-reported water sources were confirmed using the GIS-based method of water district assignment. Furthermore, the GIS-based method corrected 20,858 (15.0%) self-reported public drinking water sources. Over half (54%) the participants in the lowest GIS-based exposure group self-reported being in a higher exposed water district.

            Conclusions

            Not only were we able to correct erroneous self-reported water sources, we were also able to assign water districts to participants with unknown sources. Without the GIS-based method, the reliance on only self-reported data would have resulted in exposure misclassification.
              Cover page: Assessing the Spatial Distribution of Perfluorooctanoic Acid Exposure via Public Drinking Water Pipes Using Geographic Information SystemsCreative Commons 'BY' version 4.0 license
              • Article
              • Peer Reviewed
              UC Irvine Previously Published Works (2014)
              We investigated differences in the geographic distribution of autism spectrum disorders (ASD) over time in central North Carolina with data from the Autism and Developmental Disabilities Monitoring Network. Using generalized additive models and geographic information systems we produced maps of ASD risk in 2002–2004 and 2006–2008. Overall the risk of ASD increased 52.9 % from 2002–2004 to 2006–2008. However, the magnitude of change in risk was not uniform across the study area; while some areas experienced dramatic increases in ASD risk(>400 %), others experienced slight decreases. Generally,areas with the lowest risk in 2002–2004 experienced the greatest increases over time. Education and outreach efforts in North Carolina expanded during this period, possibly contributing to the observed leveling of risk over time.
                Cover page: Brief Report: Diminishing Geographic Variability in Autism Spectrum Disorders Over Time?
                • Article
                • Peer Reviewed
                UC Irvine Previously Published Works (2018)
                OBJECTIVE:Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of the motor neuron with very few known risk factors. We conducted a spatial epidemiologic analysis of ALS incidence in Denmark to assess the contribution of sociodemographic determinants to geographic variation. METHODS:We analyzed 4249 ALS cases (1982-2013), each with 100 controls matched on sex and birth year. Odds ratio and 95% confidence bands at birth and diagnosis/index locations were calculated using generalized additive models. We included a bivariate spatial smooth for location in our conditional logistic regression adjusted for socioeconomic status and marital status. We also conducted analyses adjusted for both birth and diagnosis addresses to separate location effects. RESULTS:We observed significantly elevated ALS odds near Copenhagen for both the birth and diagnosis period analyses. Sociodemographic factors did not explain the observed patterns. When we further adjusted our spatial analyses by including both birth and diagnosis addresses, the significant area of elevated male ALS odds by birth address shifted to northwest Denmark away from Copenhagen, and there was little evidence of variation among women. Geographic variation at diagnosis differed between male and females, suggesting that patterns are not just due to regional variation in case ascertainment. CONCLUSION:ALS incidence in Denmark is associated with both location at birth and diagnosis, suggesting that geographic variation may be due to exposures occurring at birth or closer to diagnosis, although the latter could relate to case ascertainment issues.
                  Cover page: Spatial analyses of ALS incidence in Denmark over three decades
                  • Article
                  • Peer Reviewed
                  UC Irvine Previously Published Works (2022)

                  Background

                  Spatial variability of COVID-19 cases may suggest geographic disparities of social determinants of health. Spatial analyses of population-level data may provide insight on factors that may contribute to COVID-19 transmission, hospitalization, and death.

                  Methods

                  Generalized additive models were used to map COVID-19 risk from March 2020 to February 2021 in Orange County (OC), California. We geocoded and analyzed 221,843 cases to OC census tracts within a Poisson framework while smoothing over census tract centroids. Location was randomly permuted 1000 times to test for randomness. We also separated the analyses temporally to observe if risk changed over time. COVID-19 cases, hospitalizations, and deaths were mapped across OC while adjusting for population-level demographic data in crude and adjusted models.

                  Results

                  Risk for COVID-19 cases, hospitalizations, and deaths were statistically significant in northern OC. Adjustment for demographic data substantially decreased spatial risk, but areas remained statistically significant. Inclusion of location within our models considerably decreased the magnitude of risk compared to univariate models. However, percent minority (adjusted RR: 1.06, 95%CI: 1.06, 1.07), average household size (aRR: 1.06, 95%CI: 1.05, 1.07), and percent service industry (aRR: 1.05, 95%CI: 1.04, 1.06) remained significantly associated with COVID-19 risk in adjusted spatial models. In addition, areas of risk did not change between surges and risk ratios were similar for hospitalizations and deaths.

                  Conclusion

                  Significant risk factors and areas of increased risk were identified in OC in our adjusted models and suggests that social and environmental factors contribute to the spread of COVID-19 within communities. Areas in north OC remained significant despite adjustment, but risk substantially decreased. Additional investigation of risk factors may provide insight on how to protect vulnerable populations in future infectious disease outbreaks.
                    Cover page: Effect of socioeconomic factors during the early COVID-19 pandemic: a spatial analysis
                    • Article
                    • Peer Reviewed
                    UC Irvine Previously Published Works (2012)
                    • 1 supplemental file
                    Cover page: Individual-level space-time analyses of emergency department data using generalized additive modelingCreative Commons 'BY' version 4.0 license
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