In "Chocolate's Child Slaves," CNN's David McKenzie travels into the heart of the Ivory Coast to investigate children working in the cocoa fields. (More information and air times on CNN International.)

By David McKenzie and Brent Swails, CNN

Daloa, Ivory Coast (CNN) - Chocolate’s billion-dollar industry starts with workers like Abdul. He squats with a gang of a dozen harvesters on an Ivory Coast farm.

Abdul holds the yellow cocoa pod lengthwise and gives it two quick cracks, snapping it open to reveal milky white cocoa beans. He dumps the beans on a growing pile.

Abdul is 10 years old, a three-year veteran of the job.

He has never tasted chocolate.

During the course of an investigation for CNN’s Freedom Project initiative - an investigation that went deep into the cocoa fields of Ivory Coast - a team of CNN journalists found that child labor, trafficking and slavery are rife in an industry that produces some of the world’s best-known brands.

It was not supposed to be this way.

After a series of news reports surfaced in 2001 about gross violations in the cocoa industry, lawmakers in the United States put immense pressure on the industry to change.

“We felt like the public ought to know about it, and we ought to take some action to try to stop it,” said Iowa Sen. Tom Harkin, who, together with Rep. Eliot Engel of New York, spearheaded the response. “How many people in America know that all this chocolate they are eating - candies and all of those wonderful chocolates - is being produced by terrible child labor?”

More about the Harkin-Engel Protocol

But after intense lobbying by the cocoa industry, lawmakers weren’t able to push through a law. What they got was a voluntary protocol, signed by the heads of the chocolate industry, to stop the worst forms of child labor “as a matter of urgency.” One of the key goals was to certify the cocoa trade as child-labor free.

“It was meant to achieve the end of child slave labor in cocoa fields,” Engel said.

It didn’t.

UNICEF estimates that nearly a half-million children work on farms across Ivory Coast, which produces nearly 40% of the world’s supply of cocoa. The agency says hundreds of thousands of children, many of them trafficked across borders, are engaged in the worst forms of child labor.

A recent study by Tulane University says the industry’s efforts to stop child labor are “uneven” and “incomplete” and that 97% of Ivory Coast’s farmers had not been reached. But the industry’s main representative in the country disagrees with the assessment.

“I think the situation has improved exponentially,” said Rabola Kagohi, country director for the International Cocoa Initiative, the chocolate industry’s answer to fighting child labor and trafficking. “Today, the message is physically getting through.”

Kagohi works out of a basement office with one other permanent employee.

“There are some results,” he said. “I wish that you had spoken to some planters.”

None of the farmers CNN spoke to in the heart of the cocoa production region said they had ever been reached by the International Cocoa Initiative, the government or chocolate companies about child trafficking.

Children such as Abdul don’t know anything about protocols or certification. All they know is work.

When Abdul’s mother died, a stranger brought him across the border to the farm. Abdul says all he’s given is a little food, the torn clothes on his back, and an occasional tip from the farmer. Abdul is a modern child slave.

And he is not the only youngster working in his group.

Yacou insisted he is 16, but his face looks far younger.

“My mother brought me from Burkina Faso when my father died,” he said.

Scars crisscross Yacou’s legs from a machete. He can’t clear grass in the cocoa fields without cutting himself. During harvest season, he works day after day hacking the cocoa pods.

The emotional scars run much deeper.

“I wish I could go to school. I want to read and write,” he said. But Yacou hasn’t spent a single day in school, and he has no idea how to leave the farm.

“It makes me angry,” Engel said. As far as he’s concerned, the chocolate companies haven't done enough.

“They are working with us, and we are glad that they are working with us. But they could do better.”

Read the chocolate industry responses

One of the major players in the Ivory Coast cocoa trade is, not surprisingly, the Ivorian government. Although the country has cornered a vast chunk of a lucrative market, it is considered one of the world’s poorest by any measure.

But the government leadership blames politics and war for the problems in the cocoa industry.

“Thirty years of political instability caused a lot of damage to our economy generally, and to the agricultural sector particularly, and more specifically to the cocoa industry,” said Ivory Coast’s minister of agriculture, Sangafowa Coulibaly. “Unfortunately, these years have been lost.”

After an attempted coup in 2002, the country was split in half and kept from all-out civil war by the United Nations. There was protracted violence after the last disputed presidential elections, when then-President Laurent Gbagbo refused to concede.

With the new government of Alassane Ouattara in charge, the government says it can now put much-needed reforms in place.

“Things can only get better,” Coulibaly said. “The main reason is that today, the political crisis is behind us, the armed conflict is behind us.”

But many observers believe that a new government won’t make it a priority to stop slavery in the cocoa fields.

And with peace, traffickers are free to do their work again. U.N. officials told CNN that the Ivory Coast conflict actually helped slow down trafficking because people were too afraid to move across borders.

Contrary to the promises of action, CNN’s investigation could only find promises. And those promises are empty to children like Abdul and Yacou.

– Inside the investigation: A horrible ‘normal’

– More about the human cost of chocolate

– How can you help as a consumer?

– The chocolate industry response

– All stories from "Chocolate's Child Slaves"