There is no evidence that the Indian Ocean tsunami spread illegally dumped nuclear and toxic waste on Somalia's coast, the United Nations says.
The tsunami crashed through many fishermen's homes
Samples taken from three locations in the Puntland region failed to identify any traces of toxic substances.
But the UN's humanitarian coordinator Maxwell Gaylard said there was still an urgent need for a comprehensive study.
Earlier this year, a UN official said tsunami waves appeared to have broken barrels and scattered waste.
Nick Nuttall of the UN Environment Programme had said the containers of illegally dumped waste included radioactive chemicals.
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.
Damage from December's tsunami was concentrated on the north-eastern coast of Somali, killing up to 200 people, displacing as many as 30,000 and smashing 2,400 fishing boats.