BP disputed the study, which was conducted as part of the federal Natural Resource Damage Assessment process required by the Oil Pollution Act.[163][164] The study also found that oil already broken down by wave action and chemical dispersants was more toxic than fresh oil.[165] Another peer-reviewed study, released in March 2014 and conducted by 17 scientists from the United States and Australia and published in Proceedings of the National Academy of Sciences, found that tuna and amberjack that were exposed to oil from the spill developed deformities of the heart and other organs. BP responded that the concentrations of oil in the study were a level rarely seen in the Gulf, but The New York Times reported that the BP statement was contradicted by the study.[166]