The potentially toxic substance asbestos has found its way to the shores of yet another of Singapore's southern islands.
Debris containing the mineral has washed ashore on the Sisters' Islands Marine Park.
The National Parks Board (NParks), custodian of Singapore's only marine park, said debris containing asbestos has been found in four isolated areas on Big Sister's Island. The agency said on its website yesterday that affected beaches have been sealed off. Removal works are expected to be completed by the end of next month.
Since last month, asbestos has been found on nearby Pulau Hantu, St John's Island and Kusu Island. These islands are popular among day-trippers who visit the southern islands for their nature and scenic views of the Singapore Strait, or to worship at the temple or shrine located on Kusu.
Asbestos is a fibrous mineral that was once a popular component in construction materials.
Due to its links to health problems such as lung cancer, its use in buildings was banned in Singapore in 1989, but many earlier structures still contain the substance.
Structures containing asbestos pose no risk to humans if they are intact. However, when there is damage or disturbance - such as sawing and cutting - fibres may be released into the air and inhaled.
The authorities have said repeatedly that short-term exposure to asbestos is not harmful.
However, the repeated occurrence of the mineral has raised questions on how it came to the southern islands in the first place, and if it has been dumped illegally by errant contractors.
Investigations are ongoing to determine the source of the asbestos debris.
In a joint reply to queries from The Sunday Times yesterday, the Singapore Land Authority (SLA), NParks and National Environment Agency (NEA) said the collection and disposal of general and industrial waste from offshore islands are regulated by NEA. "Owners and occupiers of premises on offshore islands manage the collection of their waste from the islands for disposal on the mainland. This includes waste generated by contractors engaged by the owners or occupiers," said the agencies.
The SLA said no asbestos debris has been found on the other southern islands - Lazarus Island, Pulau Seringat and Kias Island.
When asked about the other offshore islands open to the public, the agencies said no debris containing asbestos has been found on Coney Island, located to the mainland's north-east.
As for Pulau Ubin, off the eastern coast of Singapore, the authorities said surveys are ongoing there and are expected to be completed by early next month.
Ms Ria Tan, who documents the wildlife found on Singapore's shores, said she was heartened that the authorities were making an effort to identify and remove the asbestos.
"But it is disconcerting to learn that asbestos has been found on so many offshore islands. I hope the source and pathway of this asbestos can be identified so that this issue can be permanently resolved."
She said the authorities could work with the community for more eyes on the ground.
"I am ready to help look out for and report asbestos during my regular shore surveys. But I do not now know what to look out for," Ms Tan added.