Much of the chemical waste still remains in Abidjan
People in Ivory Coast have expressed disappointment following a trial over the dumping of hundreds of tonnes of toxic waste in Abidjan in 2006.
They said Trafigura, the Dutch company that shipped the waste, should have faced more scrutiny.
Two people were sentenced to 20 years and five years in jail over the waste, which was blamed for 17 deaths and widespread health complaints.
In 2007, Trafigura paid an out-of-court settlement relating to civil claims.
The company never admitted liability, saying the $200m (£108m) payment was made out of sympathy for the Ivorian people.
In March 2008, the Ivorian Court of Appeal ruled that there was insufficient evidence to pursue criminal charges against the company.
Denis Yao Pipira, head of the Federation of Associations of Toxic waste victims in Ivory Coast, said the full truth of the incident had not come out.
"It's absolutely necessary that the owner of the waste, the company Trafigura that chartered the Probo Koala boat [carrying the waste], have a chance to be questioned for their actions and to say which Ivorians they dealt with," he said.
The BBC's John James reports from Abidjan that satisfaction over a rare verdict being reached was tempered by frustration that some people, including high-level political figures, were not held to account.
"Me, as an individual person, I couldn't get to organise the papers to bring a boat of toxic waste into Abidjan," said one man. "It's not possible!"
"We don't have justice here in Ivory Coast."
Trafigura chartered the ship carrying the waste, which was unloaded in Ivory Coast after a failure to agree deals to get it treated in the Netherlands.
A Trafigura spokesman said the Probo Koala was calling at a number of different ports, as part of a pre-arranged route to pick up and offload gasoline cargoes.
While the Probo Koala's slops were offloaded in Abidjan when the ship docked there, the company said independent experts had found the slops could not have caused the widespread alleged illnesses.
Trafigura said it had contracted a local firm, Tommy, to handle the waste in good faith.
The head of Tommy, Nigerian national Salomon Ugborugbo, was sentenced to 20 years in jail.
Essoin Kouao, who worked as a shipping agent at the Port of Abidjan and had recommended Tommy to the Dutch company Trafigura, received a five-year prison term.
Seven others were acquitted.
Only one person from the Trafigura group - N'Zi Kablan the head of their local partner - was called to be involved in the trial.
He was supposed to be a witness but left the country days before the trial began.
This is unlikely to be the last word on the scandal, our correspondent says.
A massive class action involving thousands of victims that is prepared in the UK could begin next year.