Antonio Perreira dos Santos, 35, said he passed out from the heat at one of the pits and was given no medical attention for three days.
"They seemed unconcerned if we died. It was only through the threat of violence against them that we got them to send a sick and dying colleague out of the camp. 'If he dies, he won't be the only one,' we said, and that eventually worked."
Recently, workers at the Bascaran center have been canvassing the region and distributing cartoon booklets titled, "Keep Your Eyes Open to Avoid Becoming a Slave."
"There are about 500 cases of workers each year who manage to be rescued and file specific complaints," said Antonio Ferreira Lima, the group's director. "Most come to nothing. The government simply has little control over powerful landowners in this part of Brazil."
Meirelles said it took the authorities months to finally get out to the farm where Meirelles had left his cousin and friends behind. He refused to leave the Bascaran center until they did, and slept in the back room.
"The response times are faster now, which is good," he said. "And more people know about the risks of taking this kind of work, and thankfully, there are more jobs now here in the city so people don't have to fling themselves into the middle of nowhere for the promise of some pay."
Many of the liberated workers now do similar jobs but earn the official minimum wage of 600 reals, or about $300, a month, have safe working conditions and can visit home.
Meirelles has bought a small piece of land with the money he won in court and is building a house with his girlfriend.
"I think slavery is the right word to use for what we went through," Meirelles said. "They are conditions we did not choose."
Bevins is a special correspondent.