By Mark Abrams

PHILADELPHIA (CBS) — Student activists, professors and staff at Community College of Philadelphia staged events Tuesday to uncover what they say is an ugly secret in society.

They marched on campus for the Red Sand Walk, spreading red-colored sand in the cracks in sidewalks to get the school community to join the fight to stop human trafficking.

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Credit: Mark Abrams

Nicole Valdino, a sociology professor and organizer, says it’s an issue that has been exposed right here in Philadelphia.

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“We’ve had students say, ‘You know what, I was trafficked. I didn’t even realize I was labor trafficked.’ So, it is happening,” Valdino said. “It’s not all just marginalized individuals. It’s happening throughout our society and it’s very important that we become aware of it and make others aware.”

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Professor Ari Bank says millions are enslaved as child laborers to produce clothing, shoes and other commodities.

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“Who made this, was it a high-paid corporate executive in Bangladesh or was it some 9-year-old kid maybe getting paid 2 cents for the whole day?” he said.