Chronic toxicity of oil sands process-affected water to early life stage wood frogs ( Lithobates sylvaticus )

Oil sands process-affected water (OSPW) is a by-product of the extraction process of bitumen in the Canadian oil sands industry and is currently stored in tailings ponds on site. Wood frog embryos exposed to waterborne 80% OSPW (containing 9.1 mg/L total naphthenic acids) for 90 days exhibited a 49% ± 11.2% (mean ± 95% confidence interval) decrease in survival, whereas no mortality was observed in 1.25% to 40% OSPW treatments. Development to metamorphosis was significantly delayed in wood frogs exposed to 40% and 80% OSPW treatments, and at these concentrations, increases in mild follicular cell hypertrophy was also evident. In addition, wood frogs exposed to 20% OSPW showed significantly increased rates of scoliosis, and a severe hind limb deformity was observed after 40% OSPW exposure. Organic chemicals within OSPW were evaluated by total naphthenic acid concentrations and biomimetic extraction via solid phase microextraction analytical techniques. The findings of this study are beneficial in understanding the chronic toxicity of OSPW in a North American amphibian species.