E Coli—The Killer in Killer Lettuce

killer lettuceWhen a rash of people started getting sick at the beginning of 2018 after eating contaminated lettuce, the media was full of jibes about how the US was taking a strong stand against lettuce, which could no longer be found in supermarkets or salad bars, while guns were still easy to obtain.

By April, however, when it was reported there were a handful of deaths and hundreds sick, it was no longer a laughing matter. The FDA announced that it was the worst case of E Coli in the US in over a decade.

Finding the Source of the Killer Lettuce Problem

It seemed that the outbreak stemmed from Yuma, Arizona, the largest lettuce growing area in the United States during the winter season. After months of looking for the source, an irrigation canal was found that was polluted with the same E Coli strain, 0157:H7, which had been poisoning the lettuce. This strain of E Coli produces the Shiga Toxin that destroys red blood cells in humans.

It is not clear how the contaminated water reached the lettuce from the canal or if this was the only source of poisoned water to affect the lettuce. By the end of June, however, it seemed like everything was under control and once again lettuce became a staple in American salads. [1]

The Second Wave

However, between the 8th and 31st of October more than two dozen new cases of illness from E Coli had been reported in eleven different states in the US, as well as in Canada.

Once again the Center for Disease Control and Prevention (CDC) called for all supermarkets, restaurants and even domestic consumers to throw out all lettuce or mixed salads that contained lettuce, even if the head of lettuce had been partly consumed without bad effects. They then went on to instruct that, after all the lettuce had been disposed of, the refrigerators that contained the lettuce were to be disinfected with soap and bleach.

The source of this new outbreak has  still not been determined, in part because determining the source of contamination for lettuce is much more difficult than for beef or chicken products. There are many different opportunities to contaminate leafy products, including irrigation water, soil and fertilizer. In addition, contamination can take place anywhere along the value chain—during growing, transport or storage. To add to the problem, lettuce is a food that can’t be heated or boiled to kill contamination. [2]

The CDC did state that the second E Coli outbreak was not related to the wave earlier in the year, despite being the same strain. Sources at the CDC specified that the irrigation canal that contaminated the lettuce grown in Yuma, Arizona was definitely not the cause of the new outbreak. [3]

The Dirty Politics of Dirty Water

Since the beginning of the millennium it has been apparent in the US that there are safety issues concerning the growing of crops. There was no requirement to test the water used to irrigate crops for any pathogens, including E Coli.

In 2011, after a serious outbreak of E Coli, Congress passed a bill whereby the FDA was to enforce testing of irrigation water for all growers of fruit and vegetables in the United States. The new regulations, which were written and enacted during the Obama administration, were to come into force on January 1, 2018.

Succumbing to pressure from the growers, as well as to President Trump’s desire to deregulate as much as possible, the FDA scrapped the bill requiring irrigation water to be tested just a few months before the first deadly lettuce E Coli outbreak of 2018.

What is baffling to many scientists is why the testing was not immediately enforced after the May 2018 E Coli outbreak. Instead, the enforcement of the testing regulations has been put off until 2026. The FDA’s response is that the testing is very expensive for the growers and hence the FDA must be certain that the testing is exactly what is needed and is carried out as efficiently as possible.

Environmentalists are concerned that the FDA’s Senior Science Advisor for Produce Safety appointed in February 2018, Dr. James Gorny, is a former lobbyist for the United Fresh Produce Association, as well as the former VP of Food Safety and Technology at the Produce Marketing Association. Dr. Gorny has made it clear that it is his position that there is no need for growers to make any changes during the next few years.  [4]

The Final Note

Despite the lack of regulation many farmers are personally stepping up to the plate and taking responsibility for their produce. California and Arizona have established their own non-mandatory safety program to check the irrigation water and soil being used to grow produce.

The sentiment behind these personal and state initiatives is that every grower should want to have a high level of confidence that his produce is not contaminated and the only way to be sure of that is to test, test and test.

In the meantime, kids are relieved that they are no longer being urged to “eat your greens because they’re good for you.”


[1] Yasemin Saplakoglu, Source of E Coli in Deadly Romaine Lettuce Outbreak Finally Found June 29, 2018
[2] Cathleen O’Grady, Trash your Romaine lettuce and don’t eat any in restaurants, says the CDC, November 21, 2018
[3] Ashley Welch, CDC warns not to eat romaine lettuce amid new E coli breakout, November 20, 2018
[4] Elizabeth Shogren, The science is clear: Dirty farm water is making us sick September 27, 2018


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