Answers to readers' questions about E. coli and leafy greens

The Centers for Disease Control and Prevention has recorded 146 cases of illness due to an E. coli O157:H7 outbreak in spinach in at least 23 states to date, including two cases in Washington and one death in Wisconsin. The Food and Drug Administration advises against eating any fresh, raw spinach or products such as salad mix that contain fresh, raw spinach (conventional or organic), no matter its source, until further notice.

We asked Janet Anderberg, public health advisor with the state Department of Health's food safety program, to answer some questions from our readers.

Q: Are there lot #'s like those with dairy & other production, that can be used to back track (you know, those item codes on the bottoms of cans or on labels to be used when contacting a manufacturer?
— Toby Hilden, Seattle, WA

A: Yes, there are coding systems for trace-back with bagged product. The most user-friendly information is the "best if used by" date on the package. There are also other codes and dating systems that assist with trace-back including the UPC codes, packaging codes and Julian dates. The harvest dates are not usually on the package but that information would be available at the processing plant.

Q: how does a fecal contaminate get on leafy greens?
— rhonda, helena, mt

A: There are many ways fecal contaminants can get onto produce. The most common route is probably by water. Irrigation water can be contaminated. The contaminated water can be sprayed onto crops or fields are sometimes flooded either by natural methods (too much rain) or by purposeful irrigation methods or even accidentally. Uptake of contaminated water by a plant is also possible with some produce during the growing time or immediately after harvest (during processing). Improperly processed animal based fertilizer (manure) that is applied to a crop can also spread contaminants to produce.

Q: Do I need to worry about produce that I grow in my garden?
— Michele Leslie, seattle

A: Home grown produce is not implicated in this outbreak but you should always take precautions with any produce. Wash it thoroughly before you eat it.

Q: Are any of the problems linked to Washington state? Is there any advantage in buying directly from local farmers?
— Kris, Seattle, WA

A: So far, none of the implicated product has been linked to spinach grown in Washington, but as of today the investigation is still on-going. Buying from local farmers usually means fresher product. Local farmers are a great resource to a community.

A: Currently both organic and nonorganic spinach sources are being investigated. In the past few years there have been produce outbreaks from both organic and non organic sources. All growing methods for produce have the risk of contamination. That is why it is important to always thoroughly wash all of your produce, whether commercially grown or home grown and whether it was organically grown or not.

Q: Could this have anything to do with the practice of spraying cow manure on the fields? When my wife and I were visiting friends in Clarion Iowa during the summer of 2005 we noticed a unpleasant odor in the air. Our friend explained that it was due to a controversial new method of spraying a mixture of cow manure and water on the farmland. I notice that the farmers in our Snoqualmie valley do this too.
— George Comito, Seattle, WA

A: Spraying of manure or fertilizers on crops in not a new concept. Improper use of irrigation water and or fertilizers has been the cause of several previous outbreaks. The method of contamination for the crops involved in this outbreak however is still under investigation.

Q: Is is still OK to eat quiche that was baked at 350 degrees for 40 min.with raw triple washed spinach? I didn't wash it because it said "triple washed."
— Virginia, Orange, CA

A: Most quiche is cooked to an internal temperature of greater than 160F-170F, and that temperature will kill most vegetative, pathogenic bacteria, including E coli and Salmonella. (If your quiche was still runny in texture, then it may not have gotten hot enough!) Under normal circumstances, most triple washed produce should be safe to eat without re-washing it. The current spinach outbreak however is different. Our advice is — now is not a good time to eat fresh spinach, especially if you don't know where or how it was grown and processed.

Q: Should I avoid buying and serving prepackaged (and supposedly prewashed) salad greens to my family? Even if spinach (or any other green) is "twice washed," should I wash it again, or is that useless?
— M. Chang, Sammamish, WA

A: Packaged salads are normally a safe and efficient way of offering greens for your family. It is certainly not useless to wash it again. Washing (rinsing under cold running water) is an effective way of reducing pathogens on produce. Washing may not get rid of ALL bacteria, but washing is always better than not washing. The term 'twice washed' is frequently used by industry to mean that they have washed it for you. Washing again will further reduce an already reduced microbial load. (I always re-wash bagged product for my family.)

Q: Is the e-coli source the water in which these greens are washed, or the fertilizer used? It would seem that small, local farm greens, even if sold nonwashed, is potentially more prone to this kind of problem. Would irradiation on a large scale be an effective and feasible solution?
— M. Chang, Sammamish, WA

A: It could be either one. The investigation is on-going and we should know soon what caused the problem. Small and large farms alike have the potential for contamination of their products. As you can imagine, both small and large restaurants can cause an outbreak of foodborne disease, so can small and large farms. The difference is that a large farm or a large restaurant could potentially affect a greater number of people because they serve more products to more people.

Irradiation is very effective at killing bacteria (including e coli). Irradiation has not been found to work very well, however on most produce items. With its current application irradiation works well on some foods and not as well on others. Basically, the technology just isn't there yet to irradiate leafy greens.