ABIDJAN, Ivory Coast, Sept. 28 — It was his infant son’s cries, gasping and insistent, that first woke Salif Oudrawogol one night last month. The smell hit him moments later, wafting into the family’s hut, a noxious mélange reminiscent of rotten eggs, garlic and petroleum.

Mr. Oudrawogol went outside to investigate. Beside the family’s compound, near his manioc and corn fields, he saw a stinking slick of black sludge.

“The smell was so bad we were afraid,” Mr. Oudrawogol said. “It burned our noses and eyes.”

Over the next few days, the skin of his 6-month-old son, Salam, bloomed with blisters, which burst into weeping sores all over his body. The whole family suffered headaches, nosebleeds and stomach aches.

How that slick, a highly toxic cocktail of petrochemical waste and caustic soda, ended up in Mr. Oudrawogol’s backyard in a suburb north of Abidjan is a dark tale of globalization. It came from a Greek-owned tanker flying a Panamanian flag and leased by the London branch of a Swiss trading corporation whose fiscal headquarters are in the Netherlands. Safe disposal in Europe would have cost about $300,000, or perhaps twice that, counting the cost of delays. But because of decisions and actions made not only here but also in Europe, it was dumped on the doorstep of some of the world’s poorest people.