Genetic Testing

Written by: Paul Thompson

Primary Source:  Thornapple CSA

This week we are considering a case from the back end of the food ethics continuum: the “devious defecator.” It concerns a legal finding against Atlas Logistics Group Retail Services, an Atlanta-based grocery distributor. It seems that Atlas was having a problem policing their warehouse. They could not positively identify the culprit named above, who was engaging in serial acts of defilement at various locations around their warehouse. They decided to request DNA swabs from two employees who were suspected of the activity.

“How would this work?” the inquiring reader might ask. We consume large quantities of DNA every day. Not so much large by volume, mind you. DNA is tiny, tiny and all the DNA you eat in a week would hardly fill a teaspoon, or so I think. I can’t be sure because pursuing this question would require me to sort out whether the grams that you measure in stoichiometry are the same as the grams you measure in cooking. I know, for example, that a teaspoon of sugar weighs about 4 grams, and I just looked up the molecular weight of DNA on the Internet and found out that we rapidly get into the hundreds of grams. This would make a DNA molecule significantly larger than a 12 oz. can of Diet Coke. Since an ordinary tomato is going to contain hundreds of thousands of DNA molecules, just a single slice of tomato on a BLT would probably make you blow up like a balloon.

This result would suggest that Stephen Colbert, current host of the Late Show on CBS, would have been unable to survive the BLT with extra tomato that he got from Hello Deli owner Rupert Gee on a recent episode. In case you missed this, Bon Appetite has prepared an entry on the “best food moments” from Colbert’s tenure at the Late Show. You can find a link here.

So I think there’s something gone haywire here in my measurement tangent, which only goes to show how difficult it is for us novices to find definitive answers to important genetics questions like, “If you eat a BLT, how much DNA in the tomato is likely to come out in your poop?” Or to put it another way, you just can’t trust the Internet. It’s relevant to the problem that Atlas was facing because they were trying to use DNA analysis to identify the devious defecator. You have to think that the samples they had to work with had bunches and bunches of miscellaneous DNA bits owing to the typically diverse diets of an average citizen of Atlanta. And of course we also know that DNA is significantly degraded by the digestive process, so we would, at best, be looking at little snippets (indeed, as the scientists say, SNiPs—for Single Nucleotide Polymorphism).

But of course Atlas was less interested in what the devious defecator ate than who it was who was doing the eating (or more to the point, the pooping). Here what matters is that we humans are constantly shedding bits of our DNA. That paper cup you had coffee from this morning? There are bits of your DNA on the rim, and a surreptitious dumpster diver or street-sweeper could indeed recover enough of it to reconstruct a definitive genetic profile that would uniquely identify you as the thoughtless litterer who tossed the cup out of the pick-up window as you cruised down Grand River Avenue after a quick one from Bigby’s. And the same goes for the samples being tested by Atlas.

Of course Atlas (or the police lieutenant investigating a serial litterer, for that matter) has to have a known sample of your DNA to prove that it’s you, hence the request that two employees provide cheek swabs to find a match. It turns out, there was no match. But the employees were able to win a judgement against Atlas under the Genetic Information Nondiscrimination Act—or as we food ethics insiders call it, GINA. It seems that sweet GINA protects you from arbitrary collection and discriminatory use of genetic information that you might happen to be carelessly leaving around the environments you populate. If someone does try to keep tabs on the BLTs you are eating through running a test on your poop, you can probably sue them.

So don’t tell us the Thornapple Blog never provides useful and practical advice for daily living!

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Paul Thompson
Paul B. Thompson holds the W. K. Kellogg Chair in Agricultural, Food and Community Ethics at Michigan State University in East Lansing, Michigan. He formerly held positions in philosophy at Texas A&M University and Purdue University. His research has centered on ethical and philosophical questions associated with agriculture and food, and especially concerning the guidance and development of agricultural technoscience.
Paul Thompson

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