By 1959, the USDA's Agricultural Research Service responded to the criticism by Carson and others with a public service film, "Fire Ant on Trial"; Carson characterized it as "flagrant propaganda" that ignored the dangers that spraying pesticides (especially dieldrin and heptachlor) posed to humans and wildlife. That spring, Carson wrote a letter, published in "The Washington Post", that attributed the recent decline in bird populations—in her words, the "silencing of birds"—to pesticide overuse. That was also the year of the "Great Cranberry Scandal": the 1957, 1958, and 1959 crops of U.S. cranberries were found to contain high levels of the herbicide aminotriazole (which caused cancer in laboratory rats) and the sale of all cranberry products was halted. Carson attended the ensuing FDA hearings on revising pesticide regulations; she came away discouraged by the aggressive tactics of the chemical industry representatives, which included expert testimony that was firmly contradicted by the bulk of the scientific literature she had been studying. She also wondered about the possible "financial inducements behind certain pesticide programs."