Mystery after the appearance of hundreds of “toxic” tar balls on the beaches

Hundreds of golf ball-sized black balls have washed up on several Sydney beaches, prompting the closure of seven popular venues as authorities carry out clean-up operations and investigate their origin.

The black solid masses were confirmed to be “tar balls” after they were first spotted on Coogee Beach on Tuesday.

Since then, these mystery balls have been spotted further north at Bondi, Tamarama and Bronte beaches, leading to beach closures for swimmers, surfers and tourists.

Photos and videos showed workers wearing hazmat suits collecting the rear spheres in plastic bags as beaches remained closed.

Waverley Council closed Bondi, Bronte and Tamarama beaches as a precaution on Thursday evening, while Randwick Council closed four additional beaches, including Clovelly, Maroubra, Gordons Bay and Coogee.

Authorities have advised the public to avoid contact with the tar balls until further notice.

The New South Wales State Environmental Protection Authority said the thousands of balls were made of tar and it was carrying out its own tests.

On Wednesday evening, Randwick Council said preliminary laboratory test results suggested the dark spheres were made of tar which could form when oil comes into contact with debris and water following a oil spill or infiltration.

He said “preliminary test results…show that the material is a hydrocarbon pollutant that matches the composition of tar balls.” Hydrocarbons are mainly found in natural sources like oil, natural gas and coal.

NSW Maritime and the Australian Maritime Safety Authority said they were currently investigating the potential origins of the tar balls.

“(The Australian Maritime Safety Authority) will do reverse modeling and drift modeling, taking into account currents and wind, so that (NSW Maritime) can determine whether it is coming from the south, the north or the is off the coast of New South Wales,” director Darren Wood told ABC Radio Sydney.

However, council workers on jetskis detected a possible oil spill in the sea on Wednesday morning, Randwick Council Mayor Dylan Parker said.

But no oil spills have been reported in the area from ships, the New South Wales Ports Authority said.

“We do not yet know what happened to cause the debris to wash up on our beaches,” Mr. Parker said in a statement Thursday. “We will continue to work with the relevant authorities to ensure public safety and clean our beaches.”

Waverley Council identified the balls as being “the size of a pea to a marble” with a light grey-white colour.

“As a precautionary measure, all beaches in Waverley will be closed until further investigation has been carried out by the EPA and relevant government agencies,” the council said.

New South Wales Premier Chris Minns called it an “unusual occurrence.”

However, the NSW Ports Authority said no oil spills had been reported from the ships.

Experts believe the tar balls could be harmful to the environment and human health. Tar balls may contain polycyclic aromatic hydrocarbons (PAHs), which are known to be carcinogenic.

It can also be harmful if they enter the human body indirectly through the food chain, with individuals consuming marine products who have ingested the toxic products, they said.

Stephen Lemon, EPA executive director of operations, said the material is “fibrous” and “unusual.”

“We actually find that as we get further away from the Coogee area, the size of the balls decreases,” Mr Lemon said.

“There’s probably a lot of wave action in the surf zone, breaking up that material.”