Health Risks Associated With Arsenic and Cadmium Uptake in Wheat Grain Irrigated With Simulated Hydraulic Fracturing Flowback Water

The expansion of hydraulic fracturing throughout the U.S. has lead to increased flowback and produced water (FPW) production. One reuse option for FPW is agricultural irrigation. Reusing this waste stream to produce crops, however, has uncertain human health implications. A greenhouse experiment was performed to evaluate the plant uptake and health risks associated with consuming wheat (Triticum aestivum) irrigated with simulated flowback water containing FPW constituents arsenic and cadmium. The experiment also evaluated the impacts of tetrasodium ethylenediaminetetraacetic acid (EDTA), a common hydraulic fracturing fluid additive and metal chelator, on plant uptake. Arsenic and cadmium were applied at concentrations of 77 and 12 μg/L, respectively, based on documented flowback water sample medians. EDTA was applied at 37 mg/L, the median reported injection concentration. Arsenic and cadmium were extracted from harvested grain and quantified using inductively coupled plasma mass spectrometry (ICP-MS). Results indicated that EDTA did not significantly increase plant uptake of the applied metals. Treated grain was found to contain 6.5 times higher arsenic and 1.4 times higher cadmium concentrations than control grain. Health risk evaluations revealed elevated carcinogenic and noncarcinogenic risks associated with the ingestion of arsenic in treated wheat grain.