"They have been charged with infractions of toxic waste laws," said Justice Ministry official Ali Yeo.
Authorities prevented the two executives of commodities trader Trafigura Beheer BV from leaving the country late Saturday as they were about to board a flight to Europe. Their passports were confiscated because they had not yet appeared before a judge, Yeo said.
More than 44,000 people have sought assistance at hospitals and clinics since the toxic waste was dumped last month. Many complained of nausea, headaches and breathing difficulties. It is unclear, however, how many were seeking help for unrelated ailments to take advantage of a government offer of free medical treatment. Seven people have died but autopsies have not determined the cause of death.
The sludge, which United Nations experts say contains the potentially lethal hydrogen sulfide, arrived in Abidjan last month aboard a tanker chartered by Trafigura Beheer BV. A local contractor apparently dumped the waste in the city’s residential neighbourhoods.
Some 400 tonnes of waste were scattered at 16 different sites, ranging from ditches and roads to the main garbage dump, according to a team of experts from the UN Disaster Assessment and Coordination Mission (UNDAC). International waste removal experts began cleaning up the sludge on Sunday and the effort is expected to last up to two months.
The UN Office for the Coordination of Humanitarian Affairs (OCHA) reassured Abidjan residents on Tuesday that city’s water system had not been contaminated. Humanitarian coordinator Abdoulaye Mar Dieye, however, cautioned against eating produce grown near dumpsites.
Trafigura Beheer BV said in a statement it was "very shocked" over the arrest of its director, Claude Dauphin, and its West Africa manager, Jean-Pierre Valentini. The company said the two men had been in Abidjan on a "humanitarian mission" and had been working with the authorities as witnesses in the ongoing investigation.
A company spokeswoman, Jo Josh, told IRIN the sludge consisted of "perfectly normal gasoline blend stock", a common waste product obtained when washing oil tankers.
But UN hazardous waste expert Rudolph Walder said on Tuesday that the product dumped in Abidjan was "very clearly a hazardous waste".
"It is very clear to me that this product violates the Basel convention," said Walder.
The international Basel agreement was signed in 1989 to address hazardous waste disposal and included a special clause to protect poor nations that are less able to protect their environments from unscrupulous dumpers.
The chartered tanker, Probo Koala, tried to offload its cargo in the Dutch port of Amsterdam in July but continued on to West Africa when Trafigura considered treatment of the waste there too costly, Dutch port officials said earlier this month.
Dutch environmental police, who were alerted by residents complaining of foul-smelling fumes, are currently in Cote d'Ivoire to investigate whether the vessel was authorised to leave the Amsterdam port.
The Cote d’Ivoire government resigned nearly two weeks ago after the waste scandal broke. A new, larger Cabinet was announced on Saturday, but there were effectively few changes. The ministers of transport and environment, however, were replaced.
The government has begun an investigation into the waste scandal and suspended a number of high-ranking officials, including the general manager of the Abidjan port and the head of customs.
Meanwhile, the UN Security Council on Tuesday was set to discuss Cote d’Ivoire, which has been divided between a rebel-held north and government-run south since a coup failed to topple President Laurent Gbagbo in September 2002. His term is set to expire 31 October and it is unclear how the country will be governed thereafter.