Working conditions on sugar plantations in Brazil have in some cases been labeled as "slavery."  There are workers who are trapped in debt bondage who work at least 13 hours a day and live in miserable conditions.

A recent Amnesty International report
notes the following in regard to labor rights abuses in Brazil's sugar sector:

• Exploitation in the growing sugarcane sector continued. In March,
  attorneys working for the state Ministry for Labour rescued 288 workers
  from forced labour at six sugarcane plantations in São Paulo State. In
  the same month, 409 workers, 150 of whom were Indigenous, were rescued
  from the ethanol distillery Centro Oeste Iguatemi, in Mato Grosso do
  Sul. In November inspection teams found a further 831 Indigenous
  cutters lodged in overcrowded, insanitary and substandard
  accommodations on a plantation in Brasilândia, also in Mato Grosso do
  Sul.
• Over a thousand people working in conditions analogous to
  slavery were released from a sugar plantation owned by ethanol producer
  Pagrisa in Ulianópolis, Pará State in June. Following the raid, a
  senate commission accused the inspectors of exaggerating the workers’
  poor conditions. As a result, the work of the inspection team was
  briefly suspended by the Ministry for Labour for fear that the
  allegations would undermine the credibility of the inspection team’s
  work. Inspections resumed in October.

Conditions of slavery and forced labor in Brazil's sugar industry were also documented in the U.S. State Department's 2008 Trafficking in Persons Report.

While the government of Brazil has taken some action to stop cases of slavery on sugar plantations as well as other industries, Amnesty's Brazil researcher said that the punishment against companies using forced labor is largely "symbolic."

Ambassador Mark Lagon, the Director of the Office to Monitor and Combat Trafficking in Persons, said at a press conference to release the Trafficking in Persons Report: "I’ll call attention to the profile of Brazil, which is doing a good
deal proactively to rescue victims of forced labor, even calling them
by the name they deserve, slaves, based on commitment by President
Lula. But as it says right here in the report, approximately half of
the nearly 6,000 men freed from slave labor in 2007 were found
exploited on plantations growing sugarcane for the production of
ethanol – a growing trend.  We need to pay attention to this, and there is consumer power, the
best kind of market force, to ask the question: Are supply chains clean?"

On a related note, the Rainforest Action Network has been running a campaign against agribusiness companies Archer Daniels Midland, Bunge and Cargill.  They recently sent out an action alert calling on Bunge, which signed on to a document called the Brazilian National Agreement for the Eradication of Slave Labor, to stop buying soy from plantations in Brazil which have been found to use slave labor.  You can send an e-mail to Bunge here!

Additionally, many of the conditions found in the sugar industry in Brazil can be found in other countries too.  Check out the film The Price of Sugar to find out more about the abuses sugar workers face in the Dominican Republic.  Also, ILRF commissioned reports during the CAFTA debate about labor rights in the sugar industry and you can read reports about El Salvador, Nicaragua, Guatemala, and Costa Rica.