Shared electric scooters have taken Brisbane by storm, but a new study has found that a staggering number of riders are breaking the law.

Almost half of those riding shared e-scooters in Brisbane are riding illegally and without helmets, research published in the Medical Journal of Australia on Monday revealed.

The study conducted by Queensland’s Centre for Accident Research and Road Safety (CARRS) involved observing e-scooter riders at six locations in central Brisbane during the peak periods.

It found that two in five e-scooter riders were not wearing a properly fastened helmet.

Dockless e-scooter sharing schemes have taken off in the United States and Europe over the past few years.

International e-scooter success story and Californian tech start-up Lime received a permit to operate shared e-scooters in Brisbane from November.

More than 500,000 e-scooter trips were undertaken during the first three months of the trial.

Brisbane is the first Australian city to trial scooter-sharing, with Lime also hoping to roll out the scheme in Sydney, Melbourne and Perth.

Lime’s permit allows e-scooters to be ridden on roads “only to cross them or to avoid obstructions on footpaths,” CARRS researchers Narelle Haworth and Amy Schramm wrote.

Riders must be at least 12 years old (and supervised by an adult if under 16) and wear a bicycle helmet.

Riding on higher speed and wider roads is forbidden.

Professor Haworth and Ms Schramm observed shared and private e-scooters and bicycle traffic for four days in February.

They found that 45 per cent of the shared e-scooters they observed were ridden illegally, with the rider either: Not wearing a helmet, riding on the road, or “doubling” a passenger.

Not wearing a properly fastened helmet (no helmet or helmet not properly fastened) was the most frequent risky behaviour, and was much more common among shared than private e-scooter riders (39 per cent compared to 5 per cent), the researchers found.

“The low helmet-wearing rate among shared e-scooter riders indicates the need to ensure that helmets remain available and that police enforce helmet rules,” they concluded.

Further, whether bicycle helmet standards are adequate for e-scooters should be examined.”

In June, Brisbane City Council granted approval for 250 new electric scooters to be unleashed on the city’s streets.

The council granted new operator Neuron Mobility a licence for 600 “geo-fenced” e-scooters, the ABC reported.

“Geo-fencing” will prevent the scooters from being ridden in prohibited and dangerous areas.

At the same time, the number of Lime scooters that lack geo-fencing technology was cut from 750 to 400.

Brisbane Deputy Mayor Krista Adams said the council had “looked very hard at safety”.

E-scooters’ environmental impact

Unlike push bikes, e-scooters aren’t necessarily a healthy or environmentally friendly option.

Last month, the first peer-reviewed study of the environmental impact of e-scooters was published in the US.

Researchers found that rather than simply offering a better alternative to cars, e-scooters may instead be increasing carbon emissions by reducing the number of people cycling, walking and using public transport.

The survey of e-scooter riders undertaken by researchers at North Carolina University found that 11 per cent of users would have taken the bus, half would have cycled or walked, and slightly more than a third would have driven.