"Nor did such work make them more likely to smoke, drink alcohol excessively, or regularly use cannabis in adulthood," Dr Iosua said.
The concern was that being exposed to adult environments at a younger age could have normalised smoking and drinking.
But Dr Iosua said by age 18 only 32 per cent of the study group smoked.
New Zealand is one of the few countries that has not ratified UN recommendations to prevent children from working part-time before the legal school-leaving age of 16.
Dr Iosua said the study findings supported New Zealand's position that children are adequately protected by existing legislation, which rules out specific jobs at certain ages, such as gambling-related work, serving alcohol, or driving machinery.
Labour spokeswoman for children Jacinda Ardern, who worked three jobs as a teenager in the late 1990s, believed after-school work provided adolescents with independence.
"That was what I did to save money for university and to run my car. By and large it's a great thing for kids to experience."
However, the 33-year-old queried whether the report reflected today's situation for students who work part-time.
"Are we comparing apples with apples? I can't necessarily compare my schooling experience of the 1990s to expectations of young people today."
She said the number of hours a student worked, their amount of homework, and whether the income was for pocket money or being used to supplement the family household income, were all pressures facing today's working school children.
Pupils' part-time work
Age 11
• 5% of school children work delivering newspapers and pamphlets, gardening and mowing lawns
Age 13
• 26% work, graduating to babysitting by age 14
Age 15
• 42% are in paid, regular employment in dairies, supermarkets, restaurants and other retail and hospitality work.
A school trip to New York with that?
Allan Bauld is happy to serve burgers and fries as he saves $6000 to fly to he US with his class. Photo / Christine Cornege
Allan Bauld is saving up for a $6000 school trip to New York.
That's why he started working after school at McDonald's in Hamilton six months ago.
So far the 15-year-old has put away $1000, but with his eight-hour-a-week job and some fundraising, the Fraser High School student is confident he'll have the target amount by September next year for the accounting and economics class trip.
Allan, who earns $14.25 an hour and clears $100 a week for the four-hour shifts he does on Mondays and Wednesdays, recommends a part-time job to other school students.
"Any money that they earn is money they didn't have before. It'll just give them some more freedom."
Two-thirds of his school friends also have part-time jobs, he said.
The Year 11 student said fitting in the job around his homework was not a problem and after he has finished saving for New York he plans to start saving for university or a flat.
"I don't get much spending money from my parents because money's sort of tight, so I just make my own money."
Mum Angie Evans said her son was a "model student" who worked very hard to get ahead in life.
"He's quite independent. He is a hard worker and does a really good job."
She said Allan was likely to increase his hours at work after NCEA exams later this year
