Unfortunately for romaine lettuce enthusiasts, the E. coli problem isn’t at all over. The United States is dealing with the biggest outbreak since 2006: According to the Centers for Disease Control and Prevention, the count is currently at 98 ill people in 22 states, which includes 46 hospitalizations and no deaths. The culprit? It might just be pre-washed lettuce.

As great as bagged lettuce is to have on hand for a quick meal, there’s a major downside to pre-washed and -packaged greens: Though leafy greens in general cause a fifth of all foodborne illnesses, pre-chopped and pre-washed varieties pose even more of a risk because of the extra handling—by people and machines—that goes into creating the product, leading to an increased risk of cross-contamination, The Washington Post reports.

“Mass-produced chopped, bagged lettuce that gets shipped around the US amplifies the risk of poisoning.” —Bill Marler, a food-safety attorney

“Mass-produced chopped, bagged lettuce that gets shipped around the US amplifies the risk of poisoning,” Bill Marler, a food-safety attorney, told Vox. Likely, the produce first becomes contaminated on the farm from close proximity to animal excrement. Then the process the lettuce goes through—which includes being chopped, mixed, and bagged—enables the bacteria to grow.

That bacteria can make you sick even after packers rinse the produce (yes, even triple wash!) with a chlorine wash and even after you re-rinse it at home. Since romaine lettuce is typically eaten raw, the E. coli isn’t killed during the cooking process.

To avoid risk of illness, you should skip the bagged stuff altogether. It’s still risky to buy a head of lettuce—definitely avoid all romaine from Yuma, AZ, the scene of the crime—but certainly less so than opting for the packaged stuff. So grab your greens, wash them (extra!) well, and enjoy a salad that won’t get you sick when you’re simply trying to stay healthy.

Here’s exactly how to keep your toothbrush bacteria-free. Or, find out how one smartphone app could soon identify dangerous food bacteria.