Endocrine-Disrupting Activity of Hydraulic Fracturing Chemicals and Adverse Health Outcomes After Prenatal Exposure in Male Mice

Abstract

Oil and natural gas operations have been shown to contaminate surface and ground water with endocrine-disrupting chemicals. In the current study, we fill several gaps in our understanding of the potential environmental impacts related to this process. We measured the endocrine-disrupting activities of 24 chemicals used and/or produced by oil and gas operations for five nuclear receptors using a reporter gene assay in human endometrial cancer cells. We also quantified the concentration of 16 of these chemicals in oil and gas wastewater samples. Finally, we assessed reproductive and developmental outcomes in male C57BL/6J mice after the prenatal exposure to a mixture of these chemicals. We found that 23 commonly used oil and natural gas operation chemicals can activate or inhibit the estrogen, androgen, glucocorticoid, progesterone, and/or thyroid receptors, and mixtures of these chemicals can behave synergistically, additively, or antagonistically in vitro. Prenatal exposure to a mixture of 23 oil and gas operation chemicals at 3, 30, and 300 μg/kg · d caused decreased sperm counts and increased testes, body, heart, and thymus weights and increased serum testosterone in male mice, suggesting multiple organ system impacts. Our results suggest possible adverse developmental and reproductive health outcomes in humans and animals exposed to potential environmentally relevant levels of oil and gas operation chemicals.

Unconventional oil and gas chemicals and wastewater-impacted water samples promote adipogenesis via PPARγ-dependent and independent mechanisms in 3T3-L1 cells

“…The twenty-three UOG chemicals selected were previously assessed for bioactivities independently and in combination (Fig. S1) (Kassotis et al, 2014; Kassotis et al, 2015), and were selected on the basis of being EDCs and common-use chemicals in the UOG extraction process (Kassotis et al, 2014; Kassotis et al, 2015). An equimolar mixture of these 23 chemicals was created at 10 mM.…”

“…In addition, one produced water sample was collected at the site of a ruptured pipeline in Garfield County, CO that was actively leaking (Kassotis et al, 2015); the sample naturally separated into organic (WW1-org) and aqueous (WW1-aq) layers after collection, and we have previously reported organic contaminants in each (Kassotis et al, 2015). Multiple process controls and field blanks were collected and analyzed in both regions for endocrine bioactivities and organic chemical analyses; each was found to induce no significant bioactivity and contain no organic contaminants associated with UOG operations (Kassotis et al, 2016b; Kassotis et al, 2018b).…”

“…We have recently described both potent and efficacious adipogenic responses (triglyceride accumulation and pre-adipocyte proliferation) for various alkylphenol and alcohol ethoxylates (Kassotis et al, 2018a), suggesting that these UOG chemicals may be capable of promoting adipogenesis. In vivo , research from our laboratory reported increased male and female birth and body weights following gestational exposure to a common UOG chemical mixture (Kassotis et al, 2016a; Kassotis et al, 2015). Disparate outcomes have also been reported in epidemiological studies.…”

“…>1000 different chemicals are used for hydraulic fracturing across the US (Waxman et al, 2011; Environmental Protection Agency (EPA), 2015), many of which have been demonstrated to act as endocrine disrupting chemicals (EDCs) both in vitro and in vivo (Kassotis et al, 2014; Webb et al, 2014; Bolden et al, 2015; Kassotis et al, 2016a; Kassotis et al, 2015; He et al, 2017a; He et al, 2017b; Blewett et al, 2017a). EDCs are exogenous chemicals or mixtures of chemicals that can interfere with any aspect of hormone action (Zoeller et al, 2012; The Endocrine Disruption Exchange (TEDX), 2017; Diamanti-Kandarakis et al, 2009) and may disrupt development and contribute to disease in both humans and animals, particularly during critical windows of development (Vandenberg et al, 2012; Welshons et al, 2003).…”

“…Specifically, we selected a mixture of 23 commonly used UOG chemicals that has previously been examined in vitro and in vivo (Kassotis et al, 2014; Kassotis et al, 2016a; Kassotis et al, 2015), a subset of surface water (n = 4) extracts near a UOG wastewater-impacted site in WV, USA (Kassotis et al, 2016b), a subset of surface water samples (n = 4) near UOG spill sites in CO, USA (Kassotis et al, 2018b), and two UOG wastewater samples from CO that we have previously analytically characterized (Kassotis et al, 2015). All samples were screened for potential adipogenic activity in 3T3–L1 cells, and PPARγ activity was interrogated using a FRET reporter gene assay to further delineate mechanism (likely molecular initiating event).…”