Welfare groups and unions in Brazil, the world's biggest exporter of frozen concentrated orange juice, say 150,000 children work as pickers for up to 12 hours a day in extreme heat during the six-month picking season.
Many travel around an hour each way by lorry, perched on orange boxes. Some have been killed when trucks have run off the road. Others are injured falling off stepladders used to reach the higher fruit. Many get scarred from crawling on their knees to pick fallen oranges.
Their health and education suffer, and their hands are often dyed green by the acidity of the fruit and the pesticides sprayed over orange groves.
Britons spend pounds 450m on orange juice each year. Most of it comes from Brazil. The UK is the country's fourth-largest customer. The main British importers forbid the use of child labour by their suppliers, but a complicated production, export and import chain from orchard to supermarket shelf makes it impossible to prove which juice came from which orchard, so some juice sold in the UK will inevitably have come from fruit picked bychildren.
Last year, 14,200 tonnes of frozen concentrated juice was imported directly from Brazil. Much more is routed through the Netherlands and stored in huge "tank farms" before being shipped to Britain. The Netherlands received 263,000 tonnes from Brazil last year.
British importers insist that their suppliers employ no child labour, but welfare groups believe that some Brazilian exporters turn a blind eye to their suppliers' methods.
The Brazilian government is working hard to eradicate the problem. Big producers in the Sao Paulo region have signed up to an initiative to stop using children. However, as even they admit, 92 per cent of farms are small family enterprises which often employ entire families, including young children, and the producers have little or no control over them.
Brazilian groups opposed to child labour say the country's economic crisis means that even more children may be forced to work, to augment the family incomes. They believe that at least 3.8 million children aged between five and 14 are working in Brazil, in agriculture - cutting sugar cane, picking cotton, coffee beans or oranges - and in quarries, mines, charcoal processing sites and the footwear industry.
Ernesto Giusti, of the Central Unica dos Trabalhadores, the Brazilian equivalent of Britain's TUC, told The Independent: "When our representatives try to inspect the production zones, the farm guards get in touch with each other by walkie-talkie, call the orchard and tell the children to hide or take a walk. If they're just walking in the fields, you can't say that they're working."
A major problem is that "seals of approval" given to orange juice cans or cartons in Brazil stating that "this company is a friend of the child" are not used on exported products. "There is no way to distinguish between a company that respects the law and one that doesn't," Mr Giusti said.
The British Soft Drinks Association, which represents the UK's main importers, including Schweppes, Britvic, St Ivel, Del Monte and Gerber, says its members have ethical buying policies that demand no child labour is used.
They deal only with Brazilian companies affiliated to ABECitrus, the Brazilian Association of Citrus Exporters, which has developed a code of conduct. Its members insist on contractual agreements with the farmers from whom they buy stating that children shall not be used in picking fruit. The processing companies have introduced welfare schemes and set up schools to keep children out of the fields.
But poor families and unscrupulous gang masters still use children. Cases have been reported of youngsters being refused identity cards because acid from the fruit has eroded their fingerprints.
"When you see them in the fields, their hands are green and it doesn't wash away," said Mr Giusti.
"That's partly from the fruit, but partly from the toxic products sprayed on the oranges. Often, the fruit is sprayed even while the children are working. The skin gets badly scarred. Their fingers are almost disfigured.
"You've got to remember that working conditions are abysmal in general, for the adults, but that the children suffer even more.
"The trouble is it's a deep-rooted tradition, born out of necessity. Most of these families are illiterate. The parents take them to work, instead of sending them to school, because school is only in the morning in Brazil and the parents don't want to leave them alone all afternoon. A father says, 'Well, my father took me to work when I was so kid, so ...' and there's also a mentality of 'it's better for them to work than to steal'.''
Caio Magri, co-ordinator of Brazil's Abrinq Foundation for Children's Rights, which fights child labour, is less pessimistic. He says much has been done over the past few years - by the foundation, not the government. "In Sao Paulo state we have the situation under control. But the crisis could drive more kids back to work."
He added: "We can't be absolutely certain that the situation is clean. Two months ago, two or three kids were found working in a camp picking oranges for a big company. When it came out, the producer, Citrovita, was ostracised. They kicked out their local middlemen and said they wouldn't let it happen again.''
Trade unions in Australia have taken up the issue this week, after campaigning from their Brazilian counterparts. "There is no question that child labour is extensively used in the high season," said Max Ogden of the Australian Council of Trade.
The International Confederation of Free Trade Unions in Brussels has launched an investigation of forced labour (including child labour) throughout the Brazilian economy. The aim will be to gather enough filmed and documented evidence to pressure the EU to withdraw trade preferences from Brazil.
Christopher Burton, chairman of the Juice Importers' Association, said Brazil's producers had made vast improvements in the welfare of children in recent years. "They are spending considerable amounts of money to improve the situation," he said.
He agreed that many families took their children picking with them. "You have to look at it in the context of the country," he said. "The parents, often desperately poor, have to work to make a living. What are they supposed to do with the children? This is a country with seven million street children. It is much better that the children of these workers are with them than walking the streets.
"I have seen children out with their families, but certainly not carrying out heavy work or being treated badly."
Pedro Borio, chief of staff to Eduard Amadeo, the Brazilian Minister of Labour, said he found CUT's claim that 150,000 children were working as "hard to believe. A lot of work has been done by the government with the producers and workers' representatives and I am absolutely confident not just that it is working, but that it has worked," he said.
Sainsbury and Tesco said they operated ethical policies that included demanding their suppliers did not use child labour. They said they would take action if any of their suppliers was found to be employing children.Reuse content