Last month, global personal care leader Unilever, which owns the Dove brand, said it would start phasing out the tiny polyethylene microbeads in January. The beads are used in body and face scrubs and other exfoliants.

NSW Environment Minister Rob Stokes and environmentalist Jon Dee, founder of advocacy group DoSomething, have called for a voluntary ban by the end of 2016.

The plastics, smaller than half a millimetre, have been found in sediment in the harbour and can be ingested by worms which are in turn consumed by fish. At Middle Harbour scientists found 60-100 particles of plastic micro debris in 100 ml of sediment – among the highest levels recorded in the world.

Ms Kerr also gave away a few personal tips about her own beauty care regime.

Ms Kerr, a former Global Ambassador for Earth Hour and who famously appeared naked on 'the green issue' of Rolling Stone magazine,is the founder and managing director of family skincare firm KORA Organics.

Commenting from New York she said: "Like many other women, exfoliating plays a part in my skincare regime as I exfoliate two to three times a week, so I've specifically developed an exfoliating cream for KORA Organics that uses fine natural bamboo particles.

"I feel good knowing my customers and I aren't harming the environment by flushing plastic microbeads down the drain and ultimately into our waterways and ocean,"

"I believe in living in balance with nature, respecting our environment and making informed choices. I feel that if we all start by making small changes we can all have a positive impact on our planet.

"When I created KORA Organics, I set out to create the most natural, healthy, certified organic skincare products I could; products that weren't just good for the skin, but were also respectful and kind to our environment."

The Body Shop has also followed Unilever's lead, saying it currently has three products  containing exfoliating beads - VitaminC Cleansing Polish, Tea Tree Squeaky Clean Scrub and Vitamin E Facial Scrub.

"We began using exfoliating plastic beads in these three wash-off scrubs as they were designed for use on the facial area, where it is important to control the size and shape of the particles to ensure a gentle cleansing sensation," a statement said.

"Since these concerns have come to light, we have begun a process to replace these with naturally derived scrub particles that have similar properties. We are awaiting the completion of safety and compatibility assessments in 2015 and will begin the process of phasing out exfoliating beads once these tests are done."

Dee said if Kerr's company could make skincare products without plastic microbeads, then there was no reason why the rest of the skincare industry couldn't follow her example.

Having Miranda talk about the plastic microbead problem is a real boost to our campaign to phase them out. I'm really grateful that she's drawing public attention to this," he said.

"Also having a major company like The Body Shop announce that they're replacing plastic microbeads is very positive news and sets a precedent for other skincare companies to follow. DoSomething will be writing to the companies that have yet to commit to the phaseout and we'll be seeking their commitment to phase out plastic microbeads by the end of 2016."