Children as young as five experienced common symptoms of nicotine poisoning including severe headaches, abdominal pain, muscle weakness, coughing and breathlessness, according to a study done by the international group Plan.
"Child labourers, some as young as five, are suffering severe physical symptoms from absorbing up to 54 milligrams a day of dissolved nicotine through their skin -- the equivalent of 50 average cigarettes," said the report entitled "Hard work, little pay and long hours".
Nicotine poisoning, also known as Green Tobacco Sickness, is more severe in children due to their size and because they have not built up a tolerance to nicotine through smoking.
Up to 80,000 children in this impoverished Southern African nation are forced to work in tobacco fields instead of attending school, mainly due to poverty and hunger.
Plan said some of the child labourers work up to 12 hours a day, many for less than the equivalent of 1.7 US cents an hour and without protective clothing.
"Children also revealed the physical, sexual and emotional abuse they suffer and spoke about the need to work under these exploitative conditions to support themselves, their families and pay school fees," the report added.
Half of the 13 million citizens in Malawi live below the poverty line and on less than a dollar a day.
Known as "green gold", tobacco accounts for up to 70 percent of the country's foreign exchange earnings and employs close to a half-a-million people.
Plan said there was a lack of research into the long term effects of Green Tobacco Sickness in children, but "experts believe that it could seriously impair their development."
"The brain of a child or adolescent is particularly vulnerable to long lasting adverse neurobehavioral effects of nicotine exposure," said Neal Benowitz, a medical professor at the University of California.
Plan urged the Malawi government to "rigorously enforce existing child labour and protection laws" and plantations to provide safer, fairer working conditions for those children forced to work in estates.
Multinational companies buy the majority of Malawi's low-grade, high-nicotine burley tobacco, which is often used as a filler in cigarettes across Europe and North America.
The firms were also implored to scrutinise their suppliers more closely and strictly adhere to their own corporate responsibility guidelines.
More than 300,000 peasant farmers in Malawi grow burley, a thin-leafed brand dried in the open. The country is the world's largest exporter of burley.
Last year tobacco raked in 461 million US dollars.
The World Bank, one of the main sponsors of the country's tough economic reforms, forced the government of former dictator Kamuzu Banda in the 1980s to liberalise the growing of burley tobacco in a bid to help peasant farmers.

Copyright AFP (Agence France-Presse), 2009