FRESNO, Calif. (AP) -- The nation's fresh produce would be safer if U.S. farmers were required to adopt strict standards for growing leafy greens similar to industry-written ones devised for California growers, a Food and Drug Administration official said Friday.

Dr. David Acheson said the FDA would need authority from Congress to enact "preventative controls" over production of the nation's fresh produce like those it has in place for seafood and fresh juice.

"Having Congress give us explicit authority makes it a much more robust approach and gives more chance of success," said Acheson, the commissioner for foods.

Acheson was responding to a report by Government Accountability Office investigators that said the FDA's efforts to combat food-borne illness are hampered by insufficient staff, infrequent inspections and poor enforcement at fresh produce processing plants. He said the FDA agreed with many of the findings and began addressing them before the report was published.

Sen. Barbara Boxer, D-Calif., and Sen. Ted Kennedy, D-Mass., called for the investigation after the 2006 E. coli contamination in bagged spinach killed three people, sickened 200 others and cost the leafy greens industry $86 million. Boxer said the report "paints a frightening picture" of FDA efforts to ensure safe produce.

Since the 2006 outbreak, Acheson said, the FDA's focus has been shifting to prevention of food contamination rather than reaction to it.

After the E. coli outbreak, California growers and processors wrote their own guidelines for production to avoid further loss in consumer confidence. Enforced by inspectors from the California Department of Food and Agriculture, the guidelines set buffer zones around fields to reduce the risk of feces contamination from wildlife and establish a safe distance between produce and cattle grazing operations and feedlots.

Critics contend the plan turns farms into sterile environments devoid of grasses and other wildlife habitat that filter runoff into streams.

"It's not perfect," Acheson said of the science regarding E. coli contamination, "but I think that there is enough to move the ball forward. If we waited until the science was perfect, we'd be missing the boat, and I don't think that's in the best interest of public health."

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