"A 1974 memo from Dow Chemical describes several chemicals in a widely used farm fumigant as 'garbage.' Today, one of those useless chemicals threatens drinking water for more than 1 million people across the San Joaquin Valley. Now linked to cancer, the toxin was waste from a plastic-making process. Chemical companies often mix such leftovers to create other products to avoid the cost of disposal, says one long-time chemical engineer."

"The fumigant manufacturers, Dow and Shell Oil Co., discovered decades ago that 1,2,3-trichloropropane, or TCP, was not effective against worms called nematodes, according to documents in lawsuits filed by a dozen Valley cities against the companies. But they apparently left it in a fumigant anyway.

'TCP was a hazardous waste, not a pesticide,' said lawyer Todd Robins, who represents several Valley cities and water agencies. 'It did nothing for farmers, but Shell and Dow knowingly used their fumigants as a way to dispose of it.'

A Dow representative disputes the lawyer's statement, saying TCP never was intentionally put into the fumigant, called Telone. Nor did the company intentionally allow TCP to remain in the fumigant, he said."

Mark Grossi reports for the Fresno Bee April 21, 2012. [2]