Sludge Watch ==> Spinach contamination - sewage effluent irrigation? sludges?

[Maureen Reilly]

Sludgewatch Admin:

There has been much speculation as to whether sewage sludge or sewage effluent played a role in the Ecoli 0157 contamination of bagged spinach 
from the Salinas Valley.  It still isn't clear whether certified organic growers in the valley are allowed to used sewage effluent for irrigation.  Due to salt water
infiltration of groundwater(ocean salt water has now intruded 6 miles in from the coast due to excessive groundwater pumping)  I understand most agricultural water comes
from sewage treatment plant effluent...and may contain some pathogenic bacteria.  If there are upsets or problems  at the plant...certainly the levels of pathogens in the effluent may go up.

The sewage treatment may play a role in selectively increasing the  persistence of virulent pathogens in the sludge and wastewaters, since during the digestion process the bacteria fight it out in a 'war of all against all' that favors studier pathogens.  Ecoli 0157 is found to generally last longer in the environment than other non pathogenic strains of E.coli bacteria.  So there may be selective pressure in the sewage treatment plant that essentially selects for and reproduces the most long lived and virulent of the bacteria...which would ultimately land on the food chain from sewage effluent irrigation and land application of the sewage sludges.  

Here is an interesting piece that suggests that the Ecoli pathogenic strains are protected and persist in the soil with assistance from protozoa.
See: E.coli 1057 Persistence in the Environment:

  http://mic.sgmjournals.org/cgi/reprint/148/1/2.pdf#search=%22ecoli%20persistence%20in%20environment%22

You might wonder why sewage treatment plant sludge would come to contain E.coli 0157 which tends to be associated with cattle feces...(the cattle don't get as sick as humans do from this pathogen).  Cattle fecal waste (and the E.coli 0157) tend to enter the sewage treatment plant from slaughterhouse waste, packing house washwastes and rendering plant wastes.  The sewage effluent from the Walkerton sewage treatment plant had Ecoli 0157 for instance.


As to the ecoli contamination from the spinach in 19 states:
 The plastic packaging on the spinach and mixed greens may also play a role in creating a consistently moist environment that favors bacterial reproduction.


The story below looks at whether organic spinach was to blame....
.........................................................................................................




http://www.latimes.com/news/nationworld/wire/ats-ap_top14sep18,0,1361649.story

Company: Organic Spinach Not to Blame
By JUSTIN M. NORTON
Associated Press Writer

7:53 AM PDT, September 18, 2006

SAN FRANCISCO - The company whose fresh spinach was linked to an E. coli outbreak that's sickened at least 109 people said its organic products had been cleared of suspicion, while health officials continued working to pinpoint the bacteria source. 

The Food and Drug Administration said Monday that tampering was not suspected. 

Natural Selection Foods LLC, the country's largest grower of organic produce, said late Sunday that manufacturing codes from packages of spinach that infected patients turned over to health officials all were from non-organic spinach. Natural Selection packages both organic and conventionally grown spinach in separate areas at its San Juan Bautista plant. 

The company, however, did not immediately lift any recalls of 34 brands. Those brands include the company's own labels and those of other companies that had contracts with Natural Selection to produce or package its spinach. 

Meanwhile, Salinas-based River Ranch Fresh Foods added to its recall spring mixes containing spinach sold under the labels Hy-Vee, Fresh N' Easy and Farmers Market, FDA officials said. All contain spinach purchased from Natural Selection, they said. 

The Food and Drug Administration and California Department of Health Services planned Monday to work toward tracing the infected greens to individual farms. The inquiry will review irrigation methods, harvest conditions and other practices at farms possibly involved. 

The spinach could have been contaminated in the field or during processing. About 74 percent of the fresh-market spinach grown in the U.S. comes from California, according to the California Farm Bureau Federation. 

There is no indication that the outbreak was deliberate, said Dr. David Acheson, chief medical officer with the FDA's Center for Food Safety and Applied Nutrition. 

The FDA continued to warn consumers not to eat fresh spinach or products containing fresh spinach until further notice. 

"This is unquestionably a significant outbreak in terms of E. coli," Acheson said. 

E. coli cases linked to tainted spinach have been reported in 19 states, with Wisconsin reporting the most cases, including the death of a 77-year-old woman. 

Other states reporting cases were California, Connecticut, Idaho, Indiana, Kentucky, Maine, Michigan, Minnesota, New Mexico, Nevada, New York, Ohio, Oregon, Pennsylvania, Utah, Virginia, Washington and Wyoming, according to the CDC. 

Seven new cases reported Sunday were in states with previous illnesses, Acheson said. 

In Ohio, state health officials said they were investigating the death of a 23-month-old girl who was sickened by E. coli to determine whether the case was related to the outbreak. The girl's mother said she often buys bagged spinach. 

The Centers for Disease Control and Prevention said Sunday they've started an Atlanta-based emergency operations center to help state health agencies with E. coli testing. Epidemiologists are helping test spinach samples and stool samples of infected people, center spokeswoman Lola Russell said. 

The center is helping when state health agencies can't perform the tests or when a second opinion is needed, Russell said. 

Natural Selection recalled its packaged spinach throughout the United States, Canada and Mexico as a precaution after federal health officials said some of those hospitalized reported eating brands of prepackaged spinach distributed by the company. 

However, some restaurants and retailers may be taking spinach out of bags before selling it, so consumers shouldn't buy it at all, the FDA said. 

Boiling contaminated spinach can kill the bacteria, but washing won't eliminate it, the CDC warned. 

Federal officials stressed that the bacteria had not been isolated in products sold by Natural Selection. As the investigation continues, other brands may be implicated, officials said. 

Natural Selection was founded in 1984 by Drew and Myra Goodman. Within two years, its best-known brand, Earthbound Farm, began shipping pre-washed, packaged salad fixings, and the company's "spring mix" became a mainstay of restaurants and supermarkets. 

* __ 

On the Net: 

Center for Disease Control: http://www.cdc.gov 

Natural Selection Farms: http://www.ebfarm.com 
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