While the environmental harm from dumping the many tons of asbestos on board the ship in the marine environment is unknown, based on the estimates of the sister ship of the SÃO PAULO -- the CLEMENCEAU, the ship is believed to contain more than 300 metric tonnes of PCB-laden materials in concentrations over 50ppm. PCBs are an extremely harmful contaminant of the marine environment due to their chronic toxicity and the capacity of the chemical to biomagnify its concentrations as it moves up the marine food chain.  

Under the terms of the Stockholm Convention, POPs such as PCBs must be disposed of in such a way that the POP content is destroyed or irreversibly transformed, so they no longer exhibit the characteristics of POPs. Methods for the safe disposal of POPs have been developed and listed  by the Stockholm and Basel Conventions, and ocean disposal is not an allowed method.  Furthermore, the London Protocol prohibits the disposal of ships at sea without first thoroughly cleaning them of hazardous materials such as PCBs. 

The early claim by Brazil and the ship owner that the SÃO PAULO did not contain PCBs, while the sister ship CLEMENCEAU clearly did, has never been substantiated in any way and was but one of the suspicious claims made in the Inventory of Hazardous Materials performed by surveyors working for the Turkish buyer of the ship. On the contrary, evidence exists to suggest otherwise. When the CLEMENCEAU was surveyed in 2006 by Bureau Veritas, PCBs were found in the wiring and gaskets in high concentrations. The surveyors were alarmed enough to surmise that all the cabling and wiring in the ship was likely contaminated. The Bureau Veritas’ report stated:  “All cables (old or more recent, of any use) of the first type have a content greater than the regulation threshold, with some of them having very high content (for example, 23,350 mg/kg). 71% of the cable casings (old or more recent, of any use) of the second type have a content greater than the regulation threshold, with some having very high content (for example, 41,000 mg/kg). It is recommended that the electric cables be considered polluted by PCBs. Specific precautions are to be taken concerning cutting and handling.” 

From a YouTube video of what appears to be the decommissioning ceremony on board the ship in 2018, one can see a freeze frame of a central corridor.  Compare this to an archived photo of the CLEMENCEAU’s central corridor. It shows the same harnesses of cables in both ships. Further, the gaskets throughout the ship were also found to be contaminated with PCBs.  There has been no record of removal of the wiring or gasketry on board the SÃO PAULO since decommissioning.