Hair-pulling and tattling may seem like child's play, but bullying is alive and well in the workplace. According to a study by the Bellingham, Washington-based Workplace Bullying Institute, 49 percent of U.S. workers report being affected by bullying at work—totaling 71 million Americans.

While men are the common offenders and tend to pick on both men and women, female bullies are almost equal in number and prefer to harass other women, the study reveals.

"Forty percent of workplace bullies are women, and almost thirty percent of all bullying is between women," says Gary Namie, co-founder and director of the Workplace Bullying Institute.

"Male and female bullies tend to use the same tactics of verbal abuse and sabotage, but women will isolate another woman from the group, and deny them social contact and validation," he says. "These kinds of workers ruin jobs, careers, health, and relationships."

According to Namie, most bullies lash out because they feel threatened in some way, usually by the target's skill or social acceptance. The verbal abuse, intimidating behavior, and career sabotage that characterizes this kind of bullying can have disastrous effects on a company's bottom line.

"If you're a small, family-owned business with 15 workers, two bullies can impact your bottom line very quickly," he says. "Bullying can result in depression, anxiety, and even post-traumatic stress in targets, and that's a lot of sick days and lost productivity. It's hard to find good replacement people, so you can't afford to lose your good employees to this problem."

For that reason, Namie advises that owners should seek out bullies and fire them. "These people are too expensive to keep on your staff," he says.

The problem is identifying bullies who often look good to managers because they may be taking credit for other people's work. Namie encourages targets of bullying to appeal to management, and not as a personal problem but a business concern. "Explain how the bully's behavior is negatively affecting productivity and customer service, and focus your argument on the health of the business rather than a personal problem."