In a review of nearly four decades of food outbreaks reported to the Centers for Disease Control since the 1970s, scientists found outbreaks of illnesses associated with leafy vegetables were larger than those attributed to other food types.
This is surprising in part because of the cultural space spinach occupies. How could a vegetable that’s so nourishing, so vibrant, so low-calorie—and apparently so appealing that Popeye sometimes sucks it out of his pipe—be dangerous? The 2006 E. coli outbreak wasn’t just a one-off, either. Leafy vegetables were also responsible for the most deaths from foodborne illness between 2003 and 2012, during which time more E. coli cases were reported than in the previous 20 years. (The increase doesn’t necessarily mean food safety is worsening; it may also be attributable to more diligent monitoring by food-safety officials.) Seven people died from illnesses traced back to leafy vegetables in that time, compared with six people who died after eating contaminated fruit, and five who died after eating unsafe beef.
It’s worth noting that far more people were sickened by beef than by leafy vegetables between 2003 and 2012—mostly ground beef, some steak. Illnesses related to beef consumption represented more than half of all outbreaks that could be traced to a specific food source in that time, whereas leafy greens were implicated in nearly one-quarter of identifiable outbreaks. But the people who got sick from beef were more likely to recover than those who ate bad leafy greens.
Another troubling difference between foodborne illness from beef versus, say, spinach, is that there are several ways consumers can make meat consumption safer for themselves—including better handling of raw meat, cooking it to a safe temperature, and thorough hand-washing—whereas it’s less clear what can be done to improve the safety of leafy greens.
“Further research is needed to identify interventions to reduce the risk of illness caused by consumption of raw produce,” the authors of a CDC report wrote in August. “Ways must be found to encourage implementation of interventions such as decreasing contamination in the production of produce, vaccinating cattle, and irradiating foods.”
After the 2006 E. coli outbreak linked to spinach, investigators were able to identify environmental risk factors, but they still couldn’t say precisely how the contamination originated. On top of that, there seemed to be nothing the consumers who ate raw spinach could have done to protect themselves. Washing produce “would not have prevented the recent E. coli outbreak,” the FDA said after its investigation.
A closer look at the farming practices and consumer behaviors paints a slightly clearer picture, as Emily Bazelon wrote for Slate that year.
Spinach has taken off in popularity since the industry figured out how to sell pre-packaged baby spinach. Sales of bagged salad have risen 14 percent a year in the last decade, to $3 billion annually. To produce the bags, processing plants take greens from different farms, put them through three different chlorinated baths, dry and seal them in plastic, and then ship them to a market near you. The chlorination doesn't get rid of E. coli: To do that, you need to heat the leaves and treat them with an organic acid, which would probably make them go limp. So, by mixing greens from different farms without treating them for contamination, the processing of bagged spinach spreads E. coli once it’s present in a particular field.
In November, the agency released new produce safety rules, several years in the making, that were established as part of the 2011 Food Safety Modernization Act. They mandate minimum standards for water quality, employee health and hygiene, and biological elements used in soil (like compost and manure)—plus additional rules related to equipment, tools, facilities, and more. The FDA says the new regulations represent a “monumental shift in food safety,” though farms and businesses, depending on their size, have anywhere from one year to four years to comply with various aspects of the new rules.