I've been on a leadership crusade recently, ever since I found out that 60 percent of employees are at risk for a heart attack (or other life-threatening cardiac condition) if they are exposed to four toxic management traits, according to a massive 10-year study.

That led me to other research exposing the prevalence of toxic workplaces. I've always known such workplaces exist (having worked for two of them myself), but not to this degree. Science is now shinng a bright light on the destructive effects and unfortunate outcomes of a toxic workplace.

94 percent say they've worked with a toxic person

A 2009 survey conducted by Mitchell Kusy and Elizabeth Holloway, authors of Toxic Workplace! Managing Toxic Personalities and Their Systems of Power, found that 64 percent of people were currently working with someone they considered toxic, and 94 percent said they had worked with someone toxic during the course of their career.

In Kusy and Holloway's research, health care workers such as nurses were especially at risk. Ninety-one percent reported verbal abuse and other humiliating attacks from peers or supervisors. More than half of the respondents did not know how to respond to such attacks or how to deal with a toxic person in their workplace.

And the worst news of all? Toxicity in the workplace spreads like a virus. "Before you know it, you have caught the 'infection' and find yourself acting in ways that complement or replicate the very behaviors that are making you angry, frustrated, and/or depressed," Kusy and Holloway explain.

The cost

According to UNC Keenan-Flagler Business School, it is estimated that toxic workplaces cost U.S. employers $23.8 billion annually in the form of absenteeism, health care costs, lost productivity, and more.

A company's most valuable asset -- its people -- is rendered incapable to perform at a high level because most are too distracted by people trying to sabotage and manipulate the work environment. Ultimately, Kusy and Holloway say, toxic behaviors lower employee productivity and retention, health, and well-being.

Harvard behavioral scientist identifies six toxic behaviors

Baird Brightman, PhD, a Harvard University behavioral scientist, says the following six behaviors have the most toxic impact on organizational success:

1. Aggressiveness

Aggressive employees can undermine safety and lower productivity, because they make the people around them go into fight-or-flight mode. According to a VitalSmarts survey, "Eighty percent of bullies in the workplace affect five or more people."

2. Narcissism

Narcissistic employees have a lack of concern for others' interests, and an excessive focus on themselves, which interferes with the development of a positive and flexible culture.

3. Lack of credibility

This occurs when employees do not do what they say they are going to do. This is detrimental to building trust with colleagues.

4. Passivity

Employees simply lack initiative and fail to take ownership of their responsibilities. This pulls down productivity for the entire team and hinders overall performance.

5. Disorganization

Employees exhibiting a lack of personal organization also lack the on-the-job requirements of focus, structure, and discipline needed to get the job done.

6. Rigidity

Since the world is constantly evolving and requires continuous adaptation, employees who are resistant to change are guaranteed to become obsolete and fail. The bad news is they may take colleagues down with them.

The solution: prevention

On LinkedIn, Brightman offers some helpful strategies for preventing a toxic workplace.

Step 1: Reinvent your selection process

Brightman says, "The challenge we face is that standard selection practices such as unstructured interviews and reference checks provide weak if any protection."

To prevent the toxic candidate from entering your work force, look at improving the recruitment and selection process by implementing behavioral assessments to identify a candidate's toxic organizational behaviors (TOB).

Here's Brightman: "Alert [candidates] that they will be assessed for TOB during the initial period of employment. For candidates with self-awareness of their TOB, this information will in some cases result in their removing themselves from consideration to the benefit of their own career and the hiring organization."

Step 2: Reinvent your onboarding process, as well

Educate and coach new employees about toxic behaviors during the onboarding process, which should last for a few weeks after the initial hire. Then provide ongoing training as part of the company's efforts to prevent a hostile workplace.

Brightman goes even further, to suggest including the behavioral assessments to detect the presence of TOB early in a person's tenure to minimize its deleterious impact.

Here's Brightman: "Detection of TOB should trigger a rapid and focused intervention that includes verbal and written feedback (to convey the seriousness of the issue) accompanied by an effective improvement plan. Helping a person replace toxic with adaptive behaviors will serve the best interests of their own career and the organization as a whole."

Step 3: When all else fails, terminate

Let's face it. If all attempts at prevention don't improve a situation involving a toxic employee, termination is imminent.

Brightman says, "The remaining option is to 'cure' the organization by terminating the offending employee's tenure before even more severe damage is done."

Just have all your legal ducks in a row: "Documenting clear and ongoing communication about and efforts to ameliorate the situation lays the groundwork for a relatively smooth and legally defensible outplacement process," concludes Brightman.