Wildlife As a Source of Produce Contamination?

Could wildlife be the main culprit in the recent spate of contaminated produce – first in spinach and now in lettuce?

Nunes Company, Inc., a Salinas Valley, California-based company, has voluntarily recalled all of its lettuce, fearing the produce possibly was contaminated with irrigation water tainted with E. coli.

Testing revealed the water contained trace amounts of E. coli, though the company CEO, Tom Nunes, Jr., said he could not be sure whether the E. coli was a “generic” form or the potentially deadly E. coli O157:H7. The decision to recall the lettuce was precautionary, because no outbreaks from exposure to the lettuce have occurred.

The irrigation water was drawn from deep wells and held in a reservoir before it was applied to the lettuce. However, one federal official stressed that it was “premature” to point to water as the source of contamination.

Dr. David Acheson, quoted today by Newsday staff writer Delthia Ricks, says it is possible the contamination may stem from other, less detectable sources, such as wild animals and birds that roamed the area, possibly spreading fecal contamination from bovine species.

Also suspect are feral pigs, who are known to spread fecal matter with their feet while foraging throughout an area.

Whether this contamination was caused by birds, deer, wild pigs or some other source source entirely, Acheson says it is more important than ever for produce farmers to adopt practices aimed at minimizing the spread of fecal contamination.

Until recently, fecal contamination associated with wildlife appears to have been greatly underestimated by scientists.

However, tests conducted recently in the Potomac and Anacostia rivers reveal that many of the germs originated from wildlife waste --- a problem they attribute in large part to the heavy concentrations of deer, geese and other species living in modern suburbs.

High levels of bacterial contamination in local water systems associated with wildlife are likely to be a problem in many heavily populated areas throughout the United States, says Ted Tyson, an Extension biosystems engineer and Auburn University professor of biosystems engineering.

“Basically it’s not unrealistic at all to assume that many heavily populated urban and suburban areas throughout the country are dealing with these sorts of problems,” says Tyson, who cites figures showing that only about one-fourth of bacterial contamination comes from humans and livestock. Until recently, humans and livestock were presumed to be the biggest contributors to surface water contamination.

Dr. Jean Weese, an Alabama Cooperative Extension System food safety specialist and Auburn University professor of nutrition and food science, says wildlife-related sources of contamination are among the biggest challenges associated with the mass production of produce.

Growers can do everything in their power to minimize the risks of these types of exposure, she says, but in cases where produce is raised on hundreds of acres, there is always the chance that some contamination will go undetected.

Likewise, while many commercial farms routinely pay for random sampling of plants and even irrigated water, it is likely this sampling fails to provide an accurate assessment of risk, she says.

“To know what is in each of these products, they would have to sample everything.”

Unfortunately, she says, this is unreasonable given the high cost of testing.

Posted by Jim Langcuster at October 10, 2006 04:52 PM | TrackBack