The transboundary movement of hazardous wastes represents a commercial activity promising huge returns for the persons engaged in the movement. On the downside, hazardous waste movements may pose a substantial threat for human health and the environment. Since, moreover, hazardous wastes are usually shipped in large amounts, incidents involving hazardous wastes are likely to affect large areas with adverse effects on a potentially large number of humans, animals and natural resources. The fact that incidents may occur during each stage of a transboundary movement of hazardous wastes by sea can be illustrated in the following examples⁶:

The M/V “Khian Sea” case⁷: In 1986 the city of Philadelphia in Pennsylvania (USA) instructed a private waste management company to export 14,000 tons of toxic ash derived from a municipal incineration plant. The bulk cargo was loaded on board the M/V “Khian Sea”, which headed for the Caribbean to dump the ash on a man-made island in the Bahamas. The Bahamian government, however, refused to permit the discharge. The ash was then relabelled and the vessel tried to call at several other ports in the Caribbean, South America and Western Africa.⁸ In spring 1988, the crew finally succeeded in discharging the ash onto a beach near Gonaives in Haiti by declaring it as topsoil fertilizer. After approximately 4,000 tons had been discharged, the Haitian government recognised the true nature of the cargo and ordered the vessel to reload, which, however, left Haitian waters without reassuming the ash.⁹ Thereafter, the crew of the M/V “Khian Sea” was unsuccessful in its attempts to unload the remaining ash at several ports around the globe. The vessel was sold, reflagged and renamed, and when she arrived at Singapore in November 1988 her cargo was missing. It is assumed that the ash had been dumped into the Indian Ocean.¹⁰ Whereas two executives of the vessel operating company were sentenced to imprisonment by US courts for the dumping into the high seas, no one could be held liable for the costs of re-importation and clean-up at the Haitian shore.¹¹ It was only in 2000 that a major part of the ash located in Haiti was re-shipped to the US and finally deposited at a landfill in Pennsylvania.¹²

The M/V “Khian Sea” case is only one striking example of major environmental incidents that have occurred in the context of transboundary movements of hazardous wastes by sea. Another example of wastes being sent around the globe is the M/V “Zanoobia” case from 1987. An Italian waste management company shipped approximately 2,200 tons of chemical waste to Djibouti where the drums were intended to be buried. After the local authorities refused to allow the discharge, the cargo was sent to Venezuela for interim storage, then to Syria and finally back to Italy. Several people that came into contact with the wastes during the movement fell ill.¹³

Further examples include, amongst others, the Kassa Island incident in Guinea,¹⁴ the Koko Beach incident in Nigeria,¹⁵ the Thor Chemicals incident in South Africa¹⁶ and the Formosa incident in Cambodia.¹⁷

The M/V “Probo Koala” case¹⁸: The M/V “Probo Koala” was a Greek OBO-carrier chartered by an oil trading company with head offices in Amsterdam, Lucerne and London. In 2006, the vessel was used to temporarily store and process petrol blend stocks and naphtha while she anchored in the Mediterranean off the coast of Gibraltar. During this caustic washing process (“sweetening”), naphtha or petrol blends are mixed with caustic soda (liquid sodium hydroxide) to reduce the level of mercaptans in order to obtain tradable petrol for the African market. The highly toxic residues of this caustic washing were collected in the vessel’s slop tanks.¹⁹ In June 2006, the M/V “Probo Koala” called at the port of Amsterdam to refuel and to empty her slop tanks, whose content was declared as ordinary slops from oil tank washings. However, an unusual and pungent odour emanated from the samples taken by the port operator, so that the further discharging of the slop tank contents was prohibited.²⁰ The vessel then sailed to Paldiski in Estonia and loaded approximately 26,000 tons of petrol to be shipped to Nigeria. After delivery of the cargo the vessel called at Abidjan in Ivory Coast on 19 August 2006 and emptied her slop tanks. Approximately 528 cubic metres of chemical wastes were delivered to a local waste management company²¹ that had been founded only recently.²² The liquid wastes were simply dumped at various sites in and around Abidjan lacking any kind of soil sealing. It is officially estimated that as a result of direct contact and indirect exposure by consumption of contaminated water, groundwater and food products, 15 residents died, 69 were hospitalised and more than 108,000 people sought medical attention because of intestinal and respiratory problems, nausea and vomiting.²³ When the international public became aware of this incident the oil trading company attempted to settle this matter by mutual agreement with the Ivorian government. According to this agreement the Ivorian government received a contribution of GBP 100 million towards the costs of restoration of environmental damage and towards compensation payments for the families of killed and injured residents.²⁴ Notwithstanding this step, a class action lawsuit aggregating 31,000 residents was instituted before the London High Court in 2009, this later being withdrawn after the oil trading company agreed to an out-of-court settlement paying GBP 1,000 to each victim.²⁵