Major retailers are meeting this week to discuss worker safety in Bangladesh after a building collapse last week killed at least 433 garment factory workers.

And the death toll in the collapse will likely continue to rise—149 people are still missing, and Bangladesh officials don't think they'll find any more survivors.

Richard M. Locke, a Massachusetts Institute of Technology professor who has researched and written a book on enforcing fair labor standards within global supply chains, says retailers' demands for variety and fast production are contributing to unsafe working conditions in garment factories abroad.

"These are Western companies located in advanced democracies and ... the brands and large retailers are asking their suppliers for the same goods they produced the year before, only cheaper with shorter [production] times and more variety," he told Business Insider.

Retailers have been embracing the fast fashion model because it encourages customers to come to the store often to check for new styles. The model also cuts down on inventory, making customers feel like they have to make the purchase on the spot to guarantee it won't sell out.

The cost of doing business is also increasing—material and transportation costs have risen, but that doesn't mean all companies are willing to pay more for merchandise.

"That takes even more money out of (the factory's) pocket that they can't invest in better working conditions," he said.

Locke argues that the current system of using private companies for regulatory oversight and auditing isn't working.

When retailers—who source from these factories—and NGOs are in charge of auditing, they often use employees who can analyze payroll records and time cards but don't have training in structural or fire safety analysis.

"After over a decade, these programs just doesn't work," Locke said.

Other experts agree say that the problem will likely get worse.

"This happens all the time," Timothy Ryan, Asia department director for the American Center for International Labor Solidarity, told Business Insider last week.

"As the infrastructure ages, you're going to see more and more of this…it's a chronic problem."

A possible solution? Locke said we should ditch the private compliance system.

"Let's do something else, give these factories the kind of capabilities they need to run better factories and recognize that the ... retailers have a responsibility because we're driving these factors," he said. "Unless we change things, we're going to always see this stuff."