SAN FRANCISCO - Less than a week after U.S. Food and Drug Administration lifted its warning on fresh spinach grown in California's Salinas Valley, a popular brand of lettuce grown there was recalled Sunday over concerns about E. coli contamination.

The lettuce does not appear to have caused any illnesses, the president of Salinas-based Nunes Co. Inc. said.

A migrant worker tends to a lettuce field in Salinas, Calif., in this March 31, 2006, photo. Less than a week after the Food and Drug Administration lifted its warning on fresh spinach grown in Salinas Valley, a popular brand of lettuce grown there has been recalled over concerns about E. coli contamination. [AP]

The lettuce scare comes amid other federal warnings that some brands of spinach, bottled carrot juice and recent shipments of beef could cause grave health risks, including paralysis, respiratory failure and death.

Executives ordered the recall after learning that irrigation water may have been contaminated with E. coli, said Tom Nunes Jr., president of the company.

So far, company investigators have not found E. coli bacteria in the lettuce itself, Nunes stressed.

"We're just reacting to a water test only. We know there's generic E. coli on it, but we're not sure what that means," he said. "We're being extra careful. This is precautionary."

The recall covers green leaf lettuce purchased in grocery stores Oct. 3-6 in Arizona, California, Nevada, Washington, Oregon, Idaho and Montana. It was also sold to distributors in those states who may have sold it to restaurants or institutions.

The recalled lettuce was packaged as "Green Leaf 24 Count, waxed carton," and "Green Leaf 18 Count, cellophane sleeve, returnable carton." Packaging is stamped with lot code 6SL0024.

FDA spokeswoman Julie Zawisza said the agency is aware of the voluntary recall but had no details.

"As a standard course of action, we would expect the firm to identify the source of the contamination and take steps to ... ensure that it doesn't happen again," Zawisza wrote in an e-mail.

It's unlikely that the bacteria in the lettuce fields share the source of the E. coli found in spinach that has sickened nearly 200 people and has been linked to three deaths nationwide, Nunes said.

Pathogenic Escherichia coli bacteria, or E. coli, can proliferate in uncooked produce, raw milk, unpasteurized juice, contaminated water and meat. When consumed, it may cause diarrhea and bloody stools.

Although most healthy adults recover within a week without long-term side effects, some people may develop a form of kidney failure.

That illness is most likely to occur in young children, senior citizens and people with compromised immune systems. In extreme cases, it can lead to kidney damage or death.

The recall at Nunes Co., a family-owned business with more than 20,000 acres of cropland in Arizona and California, comes days after federal agents searched two Salinas Valley produce companies connected to the nationwide spinach scare.

Epidemiologists also warned consumers last week to stay away from some bottled carrot juice after a Florida woman was paralyzed and three people in Georgia experienced respiratory failure, apparently due to botulism poisoning.

Also on Friday, an Iowa company announced that it was recalling 5,200 pounds of ground beef suspected of having E. coli. The government said no illnesses have been reported from consumption of the beef.

The outbreaks have sparked demands to create a new federal agency in charge of food safety. Sens. Charles Schumer and Hillary Rodham Clinton, both New York Democrats, are sponsoring legislation authored by Sen. Richard Durbin (news, bio, voting record), D-Ill., to create the unified Food Safety Agency.

"This recent outbreak must be a wake-up call to get our food safety house in order, because right now it's in pure disarray," Schumer said at his Manhattan office. "We need to have one agency take charge to ensure the next outbreak isn't far worse."

The outbreaks have also devastated the economy of Salinas Valley, the self-proclaimed "Salad Bowl to the World."

Farmers in the area, about 100 miles south of San Francisco, began plowing spinach crops under and laying off workers last month, as government inspectors examined fields and packing houses for the source of the deadly outbreak.

Nunes said he upgraded safety inspection protocols in wake of the spinach scare.

"There's a high level of urgency in our industry, and we're being very proactive," Nunes said. "It's obviously based upon recent events in the produce industry and concern for customers. We just don't want anything to happen."