Concerns regarding the fast growing oil sands industry and the risk of contamination associated to the naphthenic acids have risen into environmental and regulatory groups. Naphthenic acids which occur naturally in crude oils and bitumen have been identified and characterised as primary toxicants in wastewaters associated with oil refineries and oil sands extraction activities. Respecting the zero policy discharge, the petroleum industry has accumulated large volumes of oils sands process water into tailings ponds and wetland. The toxicity and persistence of naphthenic acids is important to consider in terms of potential effects to aquatic organisms such as fish, invertebrates and aquatic plants. Environmental managers may encounter issues with toxicity arising from naphthenic acids or other related wastewater components related. This article summarizes the current available literature regarding the toxicity and fate of naphthenic acids in the environment. Strategies for identifying toxicity caused by naphthenic acids or other components in wastewaters will also be presented.