The professor says a UK study has shown bullying and other forms of conflict cost British taxpayers $1900 a year for every working adult.
A study by Queensland's Griffith University in 2001 estimated workplace bullying cost Australian businesses between $7.5-16 billion a year.
Bentley says New Zealand businesses are wasting tens of millions of dollars every year on the issue "without a doubt."
"Bullying and other psychosocial problems like stress are responsible for 50 per cent of all lost work time. The cost is in the league of muscular skeletal problems. It's a gradual problem which becomes expensive."
He says the onus is on the Government to legislate but it had its mind on other things.
Bullying has been in the headlines recently after high-profile cases at Auckland Council and at Burger King, where an employee alleged she was punched by a manager.
In the past five years seven cases appeared before the Employment Relations Authority where bullying was considered the main problem.
Of those cases, the highest amount awarded as compensation for humiliation and discrimination was $14,000 in 2007 - the employer at fault was the Ministry of Social Development.
The ERA says that doesn't include cases where bullying is part of a larger work problem.
Bentley says the figures only represent the cases coming to light.
"The vast majority are dealt with during mediation or before that point. Most people suck it up; some think it's their own problem."
He says mediation isn't the ultimate solution as it involved bullying not being recorded.
"There's a risk companies don't learn from it, the bully may move up but the hazard is still there."
The professor oversaw the first major study of workplace bullying in New Zealand in 2009 which found 18 per cent of 1750 employees from a variety of industries experienced bullying behaviour.
He explains there's no monitoring of psychosocial work environment issues in this country so it isn't possible to say for certain whether the number of bullying cases is rising or falling, but says he senses it is increasing and "rife across a number of sectors".
He picks out the public service sector which he says has a tradition of bullying as a management style.
It was renowned for poor leadership, poor organisation, frequent change and high levels of hierarchy.
A study published by Victoria University last month found 43 per cent of Public Service Association employees reported being bullied.
Bentley says bullies can be divided into two categories. Chronic bullies - usually employed at a senior level and for whom bullying is a periodic issue - and situational bullies.
The latter group used hierarchical power inappropriately and could be rehabilitated. The former needed to be removed or managed as quickly as possible because "they're causing far more trouble than they're worth for any organisation."
He says there is often a feeling among bosses that bullies are worth hanging on to, but their behaviour is counter-productive and the harm they caused spread to witnesses, colleagues, family and friends.
"It's such a waste of management time. There's also the indirect cost ... calming people down, investigating the problem, getting in consultants and replacing people when they leave."
He says the perception bullying was simply the result of a personality clash was wrong.
"If someone just had a direct approach, they'd be like that with everyone. The harm of bullying comes from knowing you're being targeted. Bullies target people who they are envious of or perceive as a threat. Their controlling needs want to get that person out of the way."
Aggressors could be two-headed and when their boss was around or an investigation was taking place, they showed their "good side."
Bentley says workplace bullying is a long way from being resolved.
"Organisations don't understand it well enough. Education is needed," he says.
Oneil's Personnel managing director Annette Sleep says an increased awareness of personal grievances has seen bullying become more insidious.
"The more obvious behaviour like screaming and yelling is considered laughable these days. It's more likely to be the quiet acidic approach dripping with sarcasm. 'How are you today? What's good about it'?"
Sleep says no amount of legislation will change human nature.
"You'll get people in positions of responsibility who'll be aware ...
but sadly there are others who thrive on conflict, confrontation and drama and happily turn a blind eye." She describes how one of her temp staff had complained about bullying to a boss but the bully was considered a successful sales person.
"Senior management had no intention of chastising this person. It ended up getting too much so she left, her confidence shattered. In a situation like that no amount of complaining to the boss would change anything one iota."
Frog Recruitment director Jane Kennelly says workplace bullying is increasing.
"Given the economic situation and pressure organisations are under, people often revert back to positions of comfort. Many are under absolute pressure personally and professionally and sometimes that amplifies the not-so-good behaviour."
Julie Cressey, the people and performance director at recruitment agency Madison Group, says organisations have shrunk in the recession with workers expected to do more with less.
"If you've got problems with bullying you're going to lose good people. There'll be a continual turnover of staff and ongoing issues."
Cressey says employers need to take claims of bullying seriously with management and HR involved.
Myriad interventions are available, she says, ranging from formal processes and communication coaching to an appreciation of different personalities and team building.
