"Evidence from other countries suggests that the incidence of violence in the New Zealand sex industry is relatively low.
"While this is encouraging news for the sex industry in New Zealand and gives some support for the merits of decriminalisation, clearly more work needs to be done to further reduce victimisation of sex workers."
A 2006 survey found 38 per cent of all sex workers in Auckland, Wellington and Christchurch had at least one adverse experience while they were working in the last year.
Sixteen per cent of those surveyed had been subject to physical violence, rape or being held against their will. Another 20 had been threatened with violence and 23 per cent had money stolen or a client refuse to pay.
Increased safety fears for Christchurch's street workers have come to light in the wake of the 2010-11 earthquakes, with sex workers calling for better lighting and security cameras.
Christchurch city councillors raised the idea of a designated red-light district on the city's Manchester St last year, including toilets, increased security measures and needle dumps but the plans were thrown out after local residents were consulted.
Dr Meriluoto said the street sector appeared to have more violence overall simply because there were more workers using alcohol and drugs than the indoor sector - a surprising factor.
"Once we controlled for the alcohol and drug use the streets no longer appeared more dangerous when it comes to violence. That was surprising."
The sex industry was decriminalised in June 2003 with the Prostitution Reform Act.
The new legal status was expected to shift sex workers from the street sector indoors to brothels, escort agencies and private work, Dr Meriluoto said.
But it has had little effect, she said.
"Street work has many benefits, including flexible working hours and not having to pay a cut of the earnings and it appears that these benefits have outweighed the perceived costs of the sector, including any security concerns, to many sex workers that have chosen to remain in the street sector."
A new survey would help researchers estimate the effects of decriminalisation and track the industry's progress since 2006, she said.