WASHINGTON (Reuters) - The listeria outbreak in cantaloupes that killed 30 people last year was likely caused by a Colorado farm's new processing equipment and lack of chlorine in its washing water, a congressional report said on Tuesday.
The bacterial infections in late summer 2011 were the deadliest foodborne illness in more than 25 years, with 146 people in 28 states affected including one miscarriage, the report by the House Energy and Commerce Committee said.
Food and Drug Administration (FDA) inspectors found several potential problems in September at Jensen Farms, the Holly, Colorado, producer of the cantaloupes. They included lack of a step to remove field heat before the melons were moved into cold storage.
After a 2010 food safety audit, the farm had bought and retrofitted potato processing equipment to replace a hydrocooler used in handling cantaloupe, the report said.
Jensen Farms also stopped chlorinating the water used to wash the cantaloupes, it said.
"FDA officials stated that the outbreak could have likely been prevented if Jensen Farms had maintained its facilities in accordance with existing FDA guidance," the report said.
Bio Food Safety Inc, a Texas auditing company, gave Jensen Farms a 95 percent, or "superior", rating, in 2010 and a 96 percent rating in July 2011 despite major and minor deficiencies both years, the report said.
Jerry Walzel, Bio Food's president, told investigators that audits only deducted from scores if a method or technique failed to follow FDA regulations. They did not deduct if FDA guidance was not followed, he said.
The FDA has no specific regulations on cantaloupe processing, only guidance.
The congressional report comes ahead of a Thursday conference at the University of California, Davis, on the listeria outbreak and ways to reduce food safety risks associated with cantaloupe.
Listeria monocytogenes is a frequent cause of U.S. food recalls in processed meats and cheeses, but contamination in fresh produce was a new development.
The elderly, pregnant women, and people with weakened immune systems are most at risk. Symptoms include fever and muscle aches, sometimes preceded by diarrhea and other gastric problems.
(Reporting by Ian Simpson. Editing by Peter Bohan)