Tsunami waves could have spread illegally dumped nuclear waste and other toxic waste on Somalia's coast, a United Nations spokesman has said.
The tsunami crashed through many fishermen's homes
Nick Nuttall of the UN Environment Programme (UNEP) told the BBC that December's tsunami appeared to have broken barrels and scattered waste.
Mr Nuttall said a preliminary UN report had found that Somalis in the northern areas were falling sick as a result.
Some firms have been dumping waste off Somalia's coast for years, the UN says.
It says international companies have been taken advantage of the fact that Somalia had no functioning government from the early 1990s until recently.
"It appears that the tsunami broke open the containers and scattered a lot of these toxic substances around," Mr Nuttall told the BBC's Focus on Africa programme.
"We are talking about radioactive chemicals, heavy metals, medical waste.. you name it," he said.
Mr Nuttall said that reports from the tsunami-hit areas in northern Somalia had found that some local villagers there had mouth bleeds and haemorrhages.
He said that some of the hazardous wastes had been linked with cancer.
"We know this hazardous waste is on the land and is being blown around in the air and being carried to villages.
"There is also a possibility - which needs to be urgently investigated - about whether some of these chemicals have got into the coastal waters.
However, the spokesman said the UNEP needed to assess the full impact for the country.
He said that the waste posed significant danger to Somalia's fishing industry and also local marine life.