30 million US workers think their workplace is toxic. Here are the 3 main factors causing toxic work cultures, according to research.

One in nine US workers experience their workplace as toxic according to research conducted by MIT.

Charlie Sull, one of the two researchers who conducted the study, said it was an epidemic of toxicity. Tens of millions of people in America are affected by this.

Bad leadership, toxic social norms and poorly designed job roles are some of the factors that can make an organization toxic.

More than four million employee Glassdoor reviews were used to identify the key drivers of toxic workplace cultures.

Insider spoke to Charlie Sull to learn how these three factors can affect a workplace.

Toxic social norms

Some behavior can become normal within a company.

There is a workplace where employees don't care about getting to meetings on time.

Everyone in the organization will not care about being on time if they are disrespectful of people's time. Sull said that that can contribute to toxicity.

He said that employees think it is ok to shout if they disagree with something.

Managers and leaders establish and maintain workplace social Norms.

According to Sull's research, some workplace social Norms can take on a life of their own.

Even if the original leaders are no longer around, social norms can persist.

The social norms that they helped start have persisted despite the fact that a toxic culture was created 10 or 15 years ago.

Toxic leadership

Senior leadership may set the rules for the rest of the organization, but Sull's research found that middle management also has a part to play.

"If you have leaders at either of the two levels who are disrespectful or abusive, you're going to have a very negative impact on your culture," he said.

Toxic cultures are often found in sub-cultures. Sull's previous research shows that toxic pockets can be created by abusive managers.

The top team does not have to be toxic. A toxic culture can be fostered by apathy or ignorant people.

Poorly designed jobs

A badly designed job role can lead to a lot of work. Uncertainty and a lot of work result from this.

When job roles aren't clearly defined, employees can end up confused about who their manager is and what responsibilities they have. This can cause stress for workers.

He said that if your role is ambiguous, that is another driver of the kind of work design that leads to toxicity.

Sull says that a healthy work culture needs employees to feel confident in managing their work.

He said that micromanaging employees can lead to distress and toxicity.