Increasing rates of nanomaterial research and production show that environmentally relevant long-term toxicity studies are needed. Carbon nanomaterials (CNM) are one of the nanomaterials with the highest number of potential applications, yet still, little of data exist regarding their fate in environment. CNM have low solubility in water, however, surface modification and organic substances, including natural organic matter, increase their solubility and affect CNM fate in environment, which may increase their bioavailability. The greatest susceptibility to CNM has been observed for crustaceans and algae with toxic endpoints at 0.25 mg/L for fullerene and 8.7 mg/L for multi-walled carbon nanotubes respectively.