(…but it really should be titled, “As if I Needed One More Thing to Worry About”)

by Ciara Gavin

There are many studies that demonstrate how effective household cleaning products can be at removing peanut proteins. Even FARE (Food Allergy Research & Education) considers dishwashers to be a good method of removing allergens from dishes.

This is all based on the idea that everyone pre-rinses their dishes and that very little of the allergen will be in the dishwasher.

Come on, really? That is NOT how everyone washes their dishes! I know – I have kids! And sometimes, on really, really good days, they load the dishwasher.  On top of that, my dishwasher is not brand new. It was really nice 11 years ago, but it has washed a load a day since then (that’s over 4,000 loads for those of you who were trying to do mental math while reading). I have seen the kind of “junk” it leaves behind, and it is not pretty. What is that stuff in the bottom of the glass that wasn’t there when I put it into the dishwasher? These are the real questions that people with allergies need to be thinking about when they eat at friends’ houses, or when they send their allergic kids over to a friend’s house to play.

So, with these important questions in mind, one of my amazing kiddos designed his Science Fair project to test them and get some answers.

He asked the question: “What happens to peanut butter in the dishwasher?” Before I give away the answer, you need to know some details first. He tested both scratched and unscratched versions of plastic, glass, ceramic, metal and wooden dishes and utensils. To each load he added one tablespoon of fluorescent peanut butter to a knife in the silverware compartment.

What’s that? You’ve never heard of fluorescent peanut butter? I hadn’t either… because it doesn’t exist. He created it by heating peanut butter and adding a non-toxic, fluorescent blue paint powder to it. To be clear, a tablespoon is a LOT of peanut butter. But, as the mom of a daughter with a passion for baking, it is nothing compared to what I have seen her try to put into the dishwasher after making peanut butter cookies! Seriously, we had to have a “Come to Jesus” meeting about how to clean peanut butter off of knives, plates, bowls and measuring cups before I would let her try any of those recipes again. (Apparently, revival has to happen more than once because I still find peanut butter-laden dishes in my dishwasher from time to time.)

So, he ran this set of dishes and the glowing peanut butter through 12 different dishwashers that ranged in age from brand spankin’ new to our gracious neighbor’s 22-year-old relic. He tested average builder-grade dishwashers and top of the line Thermadors. What he found surprised all of us!

The nicest thing about this study was how easy it was to spot the peanut butter. By making it fluoresce, all he had to do was turn the lights off and shine a black light on them. (If only all peanut butter glowed when you shined a light on it!) The glowing blue spots were easily visible and showed up all around the dishwashers. He found them on silverware, plates, bowls, cups, wooden utensils. He even found them stuck to the inside of the dishwasher sometimes, meaning that the peanut butter residue was there waiting for the next load of dishes, too. Not a single dishwasher he tested removed all of the allergens. Not one. Some were clearly better than others, but all of them left at least some glowing evidence that they aren’t perfect.

See that italicized statistic for those scratched plastic plates he tested? They had a 92% contamination rate across all types of dishwashers! I know I used plastic plates for all my kids when they were little, and their plates had scratches galore from cutting up everything into tiny, little non-choking sized bites. In all the trials he ran, only one single time were the plastic plates not COVERED in a glowing blue film. Most of the other types of dishes had a tiny spot here or there some of the time, but those scratched-up plastic plates were almost never anywhere near clean and they held onto the peanut butter like nobody’s business!

This is bad news for mommas. When you send your highly allergic toddler over to a friend or relative’s house to play, you probably pack their snack to reduce some of the risk, but in all likelihood that snack is going to be served up on a plastic plate. No one is even going to think anything about it because all the research right now says dishwashers are safe. As if you needed one more thing to worry about, right?! But seriously, knowledge is power. The more you know, the better choices you can make. If there’s even one kid out there who avoids an allergic reaction because they didn’t eat off of a plastic plate at someone else’s house, then this research has done its job.

It’s time to start re-thinking those “safe zones” and start packing your own dishes with your snacks!

All research courtesy of Ethan Gavin, budding scientist extraordinaire