Initial results released on 6 November found the debris balls contained mainly fatty acids, a small portion of petroleum hydrocarbons, and other materials, including human hair, various fibres and bacteria which are commonly associated with wastewater.

The final test — a petroleum hydrocarbon profile and biomarker analysis, also known as oil fingerprinting—showed that the petroleum hydrocarbons in the balls are similar to intermediate or heavy fuel oils, often used in shipping.

Transport for NSW Maritime closely examined weather patterns and ocean currents in the days before the event to determine whether the balls could have resulted from a marine fuel spill but did not find anything conclusive. Sydney Water also confirmed soon after the balls were reported that there were no issues with the Bondi or Malabar water resource recovery facilities.  

NSW EPA Executive Director of Regulatory Practice and Services Stephen Beaman said experts could not determine where the balls originated from as no source samples were available for comparison.  

“Since mid-October, we’ve had a dedicated team working to uncover the source of the ball-shaped debris that washed ashore on Coogee and other Eastern suburbs beaches,” Mr Beaman said.

“This has been a significant investigation involving multiple lines of inquiry, several NSW Government agencies, and scientists in two laboratories undertaking extensive standard and advanced chemical testing.

“All our work is informed by scientific evidence. In this case, despite lengthy analysis, the results of the investigation are inconclusive. This is mainly because we cannot trace the formation of the debris balls to any specific incident or one singular source.

“We remain committed to protecting the NSW environment and take all suspected pollution incidents seriously.”

The EPA is awaiting results in the coming weeks of testing on similar balls, which were collected and provided to the EPA by a Kiama community member on the weekend of 16 November.

Initial results indicate these balls contain the same materials as those washed up on Sydney beaches, but further analysis is needed.

Both EPA and Kiama Council officers have inspected Bombo Beach, but no further pollution has been observed.

The community is encouraged to report suspected pollution incidents to the NSW EPA Environment Line on 131 555. Visit our website for more information: Environment Line