By 2050 it was predicted there would be more plastic in the ocean than fish, she said, and that was now believed to be an underestimate.
Farrelly said there was harm caused by plastics that broke down into micro and nano-plastics, which broke through cell walls and would eventually get into the food chain.
Recycling wasn't working, she argued, pointing to the fact 91 per cent of plastic bottles ended up in a landfill and it was our appetite for plastic that needed to be checked.
Recycling just allowed us to continue using the amount of plastic we were in the belief it would be dealt with in the end, she said.
For Farrelly, a major step forward was to put pressure on Government and industry to reduce the amount of plastic at the production end.
"Even though I say it's not so much consumer responsibility, it needs the voices of the consumer to push up against state and industry because they're not hearing us," she said.
"We need to continue to send strong messages to retailers and manufacturers that they're wrong; we don't want their single-use stuff ... their unnecessary stuff, that we're just literally being overwhelmed with.
"We are fully capable of bringing our own bags and reusables but we do need reminding."
Farrelly said it was important for the individual to be responsible about their plastic use but it wasn't going to change the current trajectory enough.
"The whole idea of pointing the finger at the individual litterer I think is just almost laughable. We need to move beyond that now.
"Now really it is producer and state responsibility."
One idea would be a scheme that meant producers would in some way have to pay for the pathway the plastic product ends up taking.
"For a start, national mandatory product stewardship schemes that level the playing field for all plastic producers and manufacturers is definitely needed," Farrelly said.
"This would mean that all producers and manufacturers would be responsible for the full life and the real cost [of plastic]."
