Hydraulic fracturing has recently been combined with horizontal drilling to unlock previously inaccessible or unprofitable shale oil and natural gas. The hydraulic fracturing process involves the high-pressure injection of water, chemicals, and suspended solids to fracture shale or coal bed layers and release trapped natural gas or oil. The industry has reported use of over 750 chemicals, including many known or suspected endocrine disrupting chemicals (EDCs). Spills of wastewater and chemicals are common and have been shown to contaminate surface and ground water, and we have previously reported elevated estrogen and androgen receptor activities in surface and ground water near sites with natural gas drilling spills 1. We have also tested 24 chemicals used in hydraulic fracturing for EDC activity. We found antagonist activities of 21, 21, 10, 10, and 7 chemicals for the estrogen, androgen, progesterone, glucocorticoid, and thyroid receptors, respectively. Twenty-three of 24 chemicals exhibited disruption of one or more receptor systems. Our current work extends this analysis to in vitro and in vivo studies of mixtures of chemicals used in hydraulic fracturing, as previous work has reported additivity of EDCs with the same mechanism of action. Different chemical mixtures were tested in estrogen, androgen, thyroid, progesterone and glucocorticoid receptor reporter gene assays in human breast cancer cells: 1) 24 fracturing chemicals at equimolar concentrations, 2) nine chemicals at equimolar concentrations that our team has measured in fracturing wastewater, and 3) receptor-specific mixtures of chemicals at equipotent concentrations. We found evidence of additive antagonist activity for several mixtures. We are currently assessing health outcomes in mice exposed to a mixture of fracturing chemicals during gestation. Completion of these studies should substantially increase our knowledge of consequences of prenatal exposure to a complex mixture of hydraulic fracturing chemicals and of potential health risks associated with this process. 1. Kassotis, C. D.; Tillitt, D. E.; Davis, J. W.; Hormann, A. M.; Nagel, S. C., Estrogen and Androgen Receptor Activities of Hydraulic Fracturing Chemicals and Surface and Ground Water in a Drilling-Dense Region. Endocrinology 2014, 155, (3), 11.

Endocrine disrupting activity of hydraulic fracturing chemicals and health outcomes following prenatal exposure in mice

249th National Meeting (2015)

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