Astrocytes and neurons have been shown to swell across a variety of different conditions, including increases in extracellular potassium concentration (^[K+]o). The mechanisms involved in the coupling of K+ influx to water movement into cells leading to cell swelling are not well understood and remain controversial. Here, we set out to determine the effects of ^[K+]o on rapid volume responses of hippocampal CA1 pyramidal neurons and stratum radiatum astrocytes using real-time confocal volume imaging. First, we found that elevating [K+]o within a physiological range (to 6.5 mM and 10.5 mM from a baseline of 2.5 mM), and even up to pathological levels (26 mM), produced dose-dependent increases in astrocyte volume, with absolutely no effect on neuronal volume. In the absence of compensating for addition of KCl by removal of an equal amount of NaCl, neurons actually shrank in ^[K+]o, while astrocytes continued to exhibit rapid volume increases. Astrocyte swelling in ^[K+]o was not dependent on neuronal firing, aquaporin 4, the inwardly rectifying potassium channel Kir 4.1, the sodium bicarbonate cotransporter NBCe1, , or the electroneutral cotransporter, sodium-potassium-chloride cotransporter type 1 (NKCC1), but was significantly attenuated in 1 mM barium chloride (BaCl2) and by the Na+/K+ ATPase inhibitor ouabain. Effects of 1 mM BaCl2 and ouabain applied together were not additive and, together with reports that BaCl2 can inhibit the NKA at high concentrations, suggests a prominent role for the astrocyte NKA in rapid astrocyte volume increases occurring in ^[K+]o. These findings carry important implications for understanding mechanisms of cellular edema, regulation of the brain extracellular space, and brain tissue excitability.
Drawing on the traditions of environmental justice, intersectionality, and social determinants of health, and using data from the EPA's NATA 2014 estimates of cancer risk from air toxics, we demonstrate a novel quantitative approach to evaluate intersectional environmental health risks to communities: Eco-Intersectional Multilevel (EIM) modeling. Results from previous case studies were found to generalize to national-level patterns, with multiply marginalized tracts with a high percent of Black and Latinx residents, high percent femaleheaded households, lower educational attainment, and metro location experiencing the highest risk. Overall, environmental health inequalities in cancer risk from air toxics are: (1) experienced intersectionally at the community-level, (2) significant in magnitude, and (3) socially patterned across numerous intersecting axes of marginalization, including axes rarely evaluated such as gendered family structure. EIM provides an innovative approach that will enable explicit consideration of structural/institutional social processes in the social production of intersectional and geospatial inequalities.
The negative environmental, health, and social effects arising from U.S. military action in communities both domestically and abroad suggest that the military represents an understudied institutional source of environmental injustice. Moreover, scholars and activists have long argued that the state is an active or a tacit contributor to environmental inequality, thus providing an opportunity to link U.S. military activity with approaches to the state developed under critical environmental justice. We build on these literatures to ask: Does the presence of domestic military facilities significantly increase carcinogenic risks from air toxics? And do communities of color face additional military-associated carcinogenic risks? Multilevel analyses reveal that locales in closer proximity to a military facility and those exposed to greater military technological intensity, independent of each other, experience significantly higher carcinogenic risk from air toxics. We find that proximity to military facilities tends to intensify racial and ethnic environmental inequalities in exposure to airborne toxics, but in different ways for Latinx and Black populations. These results highlight the role of the state in perpetuating racial and environmental expendability as reflected in critical environmental justice and represent an important expansion of nationwide environmental justice studies on contributors to environmental inequality.
The treadmill of destruction theory identifies the military as a major contributor to environmental problems. Water resources exploitation is one major problem that has been insufficiently studied by sociologists. Utilizing the treadmill of destruction framework here, I aim to assess how the military influences water use in nations. The purpose of this article is twofold: first, I utilize the treadmill of destruction theory to explain how the military interacts with water resources through combat and civilian operations. Second, I empirically demonstrate militarization influences on freshwater withdrawals through a fixedeffect analysis of 126 countries between 1997 and 2011. Militarization is measured as the number of military personnel relative to the population and military spending as a percentage of gross domestic product. My results show that as military personnel and spending increases, there is a corresponding increase in freshwater withdrawals. My analysis suggests militarization is an important structural driver of environmental impacts including freshwater resources.
Communities of color and poor neighborhoods are disproportionately exposed to more air pollution—a pattern known as environmental injustices. Environmental injustices increase susceptibility to negative health outcomes among residents in affected communities. The structural mechanisms distributing environmental injustices in the USA are understudied. Bridging the literatures on the social determinants of health and environmental justice highlights the importance of the environmental conditions for health inequalities and sheds light on the institutional mechanisms driving environmental health inequalities. Employing a critical quantitative methods approach, we use data from an innovative state racism index to argue that systematic racialized inequalities in areas from housing to employment increase outdoor airborne environmental health risks in neighborhoods. Results of a multilevel analysis in over 65,000 census tracts demonstrate that tracts in states with higher levels of state-level Black–white gaps report greater environmental health risk exposure to outdoor air pollution. The state racism index explains four-to-ten percent of county- and state-level variation in carcinogenic risk and noncarcinogenic respiratory system risks from outdoor air toxics. The findings suggest that the disproportional exposure across communities is tied to systematic inequalities in environmental regulation and other structural elements such as housing and incarceration. Structural racism is an environmental justice issue.
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