People said the drums were abandoned at Kipevu, near Mombasa, more than a month ago by a truck driver who discovered a yellow substance leaking from the drums, the BBC reported Thursday. Since they were dumped, residents have complained of difficulty breathing, upset stomachs and chest pains.

Nitric acid was thought to be one of the chemicals but officials said they were uncertain what had been dumped, the British broadcaster said.

Kenya's environment agency shipped in sand and other materials to help neutralize the spill.

The cargo was on its way from Mombasa to a mining company in western Uganda when it was dumped, the BBC said.