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Factory Farm Responsible for Lettuce Contamination

lettuce contamination

Story at-a-glance -

  • According to the latest statistics, there were 5,760 reported foodborne outbreaks between 2009 and 2015, resulting in 100,939 illnesses, 5,699 hospitalizations and 145 deaths
  • Of these, contaminated vegetables were responsible for 10 percent of illnesses. One of the most frequent sources of this contamination is nearby concentrated animal feeding operations
  • Most recently, a multistate E. coli outbreak linked to romaine lettuce appears to have been caused by runoff from a nearby factory farm into a canal. Water from the canal was used to irrigate the lettuce
  • It was the largest E. coli outbreak in 12 years, infecting 210 people in 36 states, hospitalizing 96 (27 of whom developed kidney failure) and killing five
  • Many enjoy the convenience of prewashed produce sold in bags, clamshells and tubs. Unfortunately, these products are the ones most frequently implicated in outbreaks associated with foodborne illness

By Dr. Mercola

According to the latest Centers for Disease Control and Prevention (CDC) statistics,1 there were 5,760 reported foodborne outbreaks between 2009 and 2015, resulting in 100,939 illnesses, 5,699 hospitalizations and 145 deaths. Contaminated vegetables were responsible for 10 percent of these illnesses.

Most people tend to associate foodborne illness with insufficiently cooked meats and, indeed, chicken causes the greatest number of outbreak-associated illnesses. Between 2009 and 2015, contaminated chicken was responsible for 12 percent of foodborne illnesses.

But what would cause a vegetable to be contaminated with a pathogen capable of making you sick? In short: contamination from concentrated animal feeding operations (CAFOs). Most recently, an E. coli outbreak traced back to romaine lettuce appears to have been caused by runoff from a nearby cattle farm.

Lettuce Contamination Traced back to CAFO

At the end of June, the CDC posted its final update on the spring outbreak of E. coli infections linked to romaine lettuce — the largest E. coli outbreak in 12 years — stating it had infected 210 people in 36 states, hospitalizing 96 (27 of whom developed kidney failure) and killing five.

While many E. coli strains are harmless or well-tolerated, this particular strain, known as (STEC) O157:H7, is a Shiga toxin-producing type of E. coli. In the U.S., an estimated 265,000 people suffer from STEC infections annually, and the O157:H7 variety is responsible for more than one-third of those illnesses.2 Generally, symptoms appear one to 10 days after eating the contaminated food and may include bloody diarrhea, stomach cramps and vomiting.

"Epidemiologic, laboratory and traceback evidence indicated that romaine lettuce from the Yuma [Arizona] growing region was the likely source," CDC notes, adding the U.S. Food and Drug Administration (FDA) was conducting an investigation to determine how E. coli entered the water that contaminated the lettuce.

The FDA now believes it has the answer.3,4 As suspected, the source of the bacteria appears to be a CAFO in the vicinity of the lettuce farm. Runoff from its manure lagoons is thought to have entered and contaminated a nearby canal, and this E. coli-tainted water was then used for irrigation on the lettuce fields.

Many consumers, in the U.S. and elsewhere, enjoy the convenience of prewashed produce sold in bags, clamshells and tubs. Unfortunately, these types of greens are the ones most frequently implicated in foodborne illness outbreaks.

In fact, says The Washington Post,5 food safety experts suggest "convenience greens — those handy bags of prechopped and prewashed salads — carry an extra risk because they come in contact with more people and machinery before they arrive on your plate."

CAFO Pollution Threatens Public Health in More Ways Than One

CAFOs are a major source of pollution that threatens public health in several ways, both directly and indirectly. Not only is CAFO meat far more prone to contamination with bacteria — including antibiotic-resistant strains — as evidenced by recent food tests, but these industrial farms also spread dangerous pathogens into the environment.

It's already been proven that CAFOs are a major source of water contamination throughout the U.S. As noted by the Arizona Department of Environmental Quality:6

"Nationwide and in Arizona, the potential for surface and ground water pollution exists through livestock facility discharge of manure-contaminated run off to natural waterways and through wastewater leaching to aquifers."

Animals create plenty of manure. Normally, this is not a problem, provided the animals are roaming on open pasture where the manure gets trampled into the ground and becomes part of the natural, regenerative cycle of the land. In fact, grazing animals are an important part of regenerative land management.

CAFOs, on the other hand, crowd animals into tight spaces, and all that manure and urine get funneled into massive open-air cesspools.7 When these pools break, leak or overflow, dangerous microbes and nitrate pollution enter the groundwater and/or nearby waterways. As noted by the Natural Resources Defense Council (NRDC):8

"Factory-farm lagoons also emit toxic gases such as ammonia, hydrogen sulfide and methane. What's more, the farms often spray the manure onto land, ostensibly as fertilizer — these 'sprayfields' bring still more of these harmful substances into our air and water."

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E. Coli Can Also Spread Via Air

Guidelines require greens be planted a minimum of 394 feet (120 meters) from cattle feedlots, but research9,10 published in the journal Applied and Environmental Microbiology found E. coli contamination (including the potentially deadly O157:H7) occurred on greens planted as far as 590 feet (180 meters) away.11 According to the researchers:

"E. coli O157:H7 was recovered from 3.5 percent of leafy green samples per plot at 60 (meters), which was higher than the 1.8 percent of positive samples per plot at 180 (meters), indicating a decrease in contamination as distance from the feedlot was increased.

Although E. coli O157:H7 was not recovered from air samples at any distance, total E. coli was recovered from air samples at the feedlot edge and all plot distances, indicating that airborne transport of the pathogen can occur …

Current leafy green field distance guidelines of 120 m (394 feet) may not be adequate to limit the transmission of E. coli O157:H7 to produce crops planted near concentrated animal feeding operations."

How to Safeguard Your Health

Research suggests that pathogens that cause food poisoning, such as E. coli, salmonella, campylobacter and certain viruses, may lead to long-term effects, including "reactive arthritis,"12 irritable bowel syndrome, kidney failure and Guillain-Barre syndrome.

So, how can you keep yourself and your family safe from foodborne illness? Colorado State University offers the following guidelines to minimize the risk of bacterial contaminants on your produce:13

Before handling and preparing produce, wash your hands with soap and water, and clean your countertops, cutting board and cutting utensils. Use separate cutting boards for meats and produce to avoid cross contamination

Buy local food to reduce transport time and distance, as bacterial growth continues over time. The fresher the food is, the lower it bacterial load will be

Store produce safely, away from raw meats, poultry and seafood to prevent cross contamination in your fridge

Lastly, while no washing method will remove 100 percent of the microbes present, thoroughly rinsing the produce under running water while briskly rubbing it with your hands is an effective way to remove most microorganisms.

Wait to wash your produce until you're ready to use it. Washing before storing will make the food spoil faster. The water also should be no more than 10 degrees F cooler than the produce in order to prevent microorganisms from entering the stem or blossom end of the produce.

To remove pesticide residues, you can use a baking soda bath, which has been shown to remove pesticides and other toxins from produce far more effectively than bleach.

Avoid commercial fruit and vegetable washes. Not only are they not much more effective than water alone,14 but the FDA even warns against them, noting the safety of the residues has not been established

Consider Growing More of Your Own Food

In my opinion, your very best option is to grow your own food. Whether that be in a vegetable garden, in containers or in trays, you won't regret the time and energy you invest in cultivating healthy, homegrown food. Greens such as lettuce are among the easiest garden vegetables to grow, and they are prolific.

By planting new seeds every 10 days, you can receive multiple harvests throughout the growing season. Depending on where you live, you may even be able to grow certain greens year-round. To get started, see "How to Grow Your Own Food."

If gardening is just not your thing, consider purchasing your greens from a local farmers market15 instead of the grocery store. Other resources that can help you locate farm-fresh and locally grown foods include:

Demeter USA — provides a directory of certified Biodynamic farms and brands. This directory can also be found on

American Grassfed Association — The goal of the American Grassfed Association is to promote the grass fed industry through government relations, research, concept marketing and public education. Their website also allows you to search for AGA approved producers certified according to strict standards that include being raised on a diet of 100 percent forage; raised on pasture and never confined to a feedlot; never treated with antibiotics or hormones; born and raised on American family farms. — provides lists of farmers known to produce raw dairy products as well as grass fed beef and other farm-fresh produce (although not all are certified organic). Here you can also find information about local farmers markets, as well as local stores and restaurants that sell grass fed products.

Weston A. Price Foundation — Weston A. Price has local chapters in most states, and many of them are connected with buying clubs in which you can easily purchase organic foods, including grass fed raw dairy products like milk and butter.

Grassfed Exchange — The Grassfed Exchange has a listing of producers selling organic and grass fed meats across the U.S.

Local Harvest — This website will help you find farmers markets, family farms and other sources of sustainably grown food in your area where you can buy produce, grass fed meats and many other goodies.

Farmers Markets — A national listing of farmers markets.

Eat Well Guide: Wholesome Food from Healthy Animals — The Eat Well Guide is a free online directory of sustainably raised meat, poultry, dairy and eggs from farms, stores, restaurants, inns, hotels and online outlets in the United States and Canada.

Community Involved in Sustaining Agriculture (CISA) — CISA is dedicated to sustaining agriculture and promoting the products of small farms.

FoodRoutes — The FoodRoutes "Find Good Food" map can help you connect with local farmers to find the freshest, tastiest food possible. On their interactive map, you can find a listing for local farmers, CSAs and markets near you.

The Cornucopia Institute — The Cornucopia Institute maintains web-based tools rating all certified organic brands of eggs, dairy products and other commodities, based on their ethical sourcing and authentic farming practices separating CAFO "organic" production from authentic organic practices. — If you're still unsure of where to find raw milk, check out and They can tell you what the status is for legality in your state, and provide a listing of raw dairy farms in your area. The Farm to Consumer Legal Defense Fund16 also provides a state-by-state review of raw milk laws.17 California residents can also find raw milk retailers using the store locator available at