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Introduction: The widespread presence of plastics in our environment poses a growing concern as they may pose risks to human and environmental health. Microplastics (MPs) are small particles generated through fragmentation of larger plastic items. The presence of MPs particles has been reported in the human placenta, an organ essential for pregnancy and fetal development. The presence of MP contamination of the womb raises the possibility of adverse effects on the developing fetus with potential life-long consequences. This thesis seeks to investigate this issue through: 1) A review aimed to examine the current state of knowledge on the effects of exposure to MP on maternal and fetal health within the DOHaD framework; 2) A study conducted to confirm and further the reports of microplastics in human placentas through a study, in a Canadian setting, comparing MPs exposure to delivery methods. Methods: 1) A review was conducted of the current literature on microplastic contamination in human reproductive tissues, and the resulting reproductive consequences of exposure. 2) Placentas (n=10) were collected from singleton, uncomplicated pregnancies. Placentas were collected from vaginal (n=5) and cesarean section (n=5) deliveries within a plastics-reduced clinical setting. Placental tissue biopsies were micro-dissected under plastic-reduced conditions - from basal plate, chorionic villous and chorionic plate. Samples were chemically digested and filtered through glass microfiber filters and the retained particles were identified and characterized using Raman microspectroscopy. iii Results: 1) The review reports multiple lines of evidence that suggest that MP-exposure prior to or during pregnancy can contaminate various internal tissues (including those of the fetus) and may result in potential adverse effects on fertility, fetal development and long-term health of the exposed fetus. More importantly, the available evidence is limited and several significant gaps in knowledge were identified. 2) Microplastics composed of various polymer types were detected in placentas from both delivery types (vaginal or caesarian), with polyethylene being the most common. In addition, non-plastic foreign particles including graphite, lead oxide and black carbon were observed in a higher frequency than microplastics. Notably, both microplastic and non-microplastic particles were found in all placentas sampled with variations in the number of particles. Particles both plastic and non-plastic were observed in placenta regions of maternal and fetal circulation suggesting that these can pass through the placenta into fetal tissues. Conclusion: This thesis provides evidence that the human placenta can serve as a reservoir for the accumulation of a variety of foreign particles during pregnancy. The potential human health impacts of such particles in general or on fetal development, in particular, are unknown but is a critical question for future work to understand the health consequences of plastic pollution.

My dissertation examines three factors that influence women's workplace inequality: the Pregnancy Discrimination Act, the U.S. Supreme Court ruling in Meritor Saving Bank v. Vinson, and women "opting out" (i.e., voluntarily leaving) of work to take care of their families. Each of the three essays attempts to resolve one or more fundamental questions in the literature on women's workplace inequality. Additionally, each of these factors is described in its own essay, and these essays are presented in chronological order of the events they discuss. The first substantive chapter, Chapter Two, examines the association between the 1978 Pregnancy Discrimination Act (PDA) and women's employment rates, men's employment rates, and women's disadvantage in employment rates. The PDA declared pregnancy discrimination a type of sex-based discrimination, making it illegal under Title VII. Among other provisions, the PDA extended temporary disability benefits (TDB) to pregnant workers who were already covered by TDB for non-pregnancy-related conditions. This extension was designed to increase the likelihood of women's returning to work after giving birth. There is a debate within the literature on whether the PDA positively affected women, hurt women, or had no effect on women. This paper uses difference-in-difference modeling with Current Population Survey data from 1968 to 2010 to weigh in on this debate. There is a positive association between the PDA and the difference between men's and women's employment because it narrows the gap between women's and men's employment rates. However, the PDA had no effect on women's employment rates and a negative effect on men's employment rates. Chapter Three examines the association between wages and the 1986 U.S. Supreme Court decision in Meritor Savings Bank v. Vinson, which declared workplace sexual harassment illegal under Title VII of the 1964 Civil Rights Act. I test two hypotheses, a "naïve hypothesis," which argues that anti-sexual harassment policies increase women's wages, and a "critical hypothesis," which contends that these policies hurt or had no effect on women's wages. Using a difference-in-difference model with Current Population Survey data from 1977 to 2010, I find that there is a negative association between Meritor and women's wages. Furthermore, I find no association between Meritor and either men's wages or the gender wage ratio. Finally, Chapter Four examines the association between women opting out and socioeconomic status (SES). I explore two contrasting storylines within the opting out literature. The first storyline focuses on the lives of high-SES women and the likelihood that they opt out. The other storyline focuses on the lives of low-SES women and the likelihood that they opt out. It is important to note that neither storyline denies the existence of the other, but research that focuses solely on one class of women may miss a significant part of the story. Using the Current Population Survey from 1980 to 2009, I first describe the trends of opting out over this 30-year span. I then test six SES-related variables (education of spouse, education of respondent, household income, below poverty line, receive welfare income, and receive food stamps). I find that low-SES women are opting out at similar rates between 1980 and 2009, but the rates for high-SES women have declined. Additionally, I find overwhelming evidence that low-SES women are more likely to opt out. / Sociology