Molecules: You'd better learn to live with them.
In the news this week: aminopyralid:
Aminopyralid is an herbicide that may have made its way into some manure destined for home gardens and may have resulted in inferior produce. Interestingly, they think it's in manure not because of topical contamination, but via animals that ate contaminated silage:
It appears that the contamination came from grass treated 12 months ago. Experts say the grass was probably made into silage, then fed to cattle during the winter months. The herbicide remained present in the silage, passed through the animal and into manure that was later sold. Horses fed on hay that had been treated could also be a channel.
Tell me this: if you were a microbe, wouldn't you munch on that? Or if you were a liver, wouldn't you glycosylate that? I will admit to huge swaths of empty space where my understanding of pharmacokinetics/xenobiotic metabolism should be, but I'm surprised it makes its way out unscathed.
Life Science
Medicine & Health
Comments
It is indeed a bitt odd that it survives but I think there may be a rather subtle explanation: Normally a 2-Cl pyridine would be very reactive to substitution with electrophiles but here we have amino substitution on the ring that makes the ring more electron rich, on top of that there is also the carboxylate which is ionized at physiological pH, which does the same thing. The amino group sitting on a pyridine ring is not very reactive so I think there is a mutual cancelation of reactivity in all the groups. Interesting. Either very clever molecular design or dumb luck. I know what I think.
Posted by: Nanono | July 1, 2008 1:58 AM
Sprayed, environmentally degraded, fermented, digested, excreted, composted, and still active! When did you ever have an amino pyridine that didn't go to crud in air as you watched it? Let's recycle human sewage directly into drinking water. Nobody ingests and excretes pharma - therapeutic or recreational - right?
Posted by: Uncle Al | July 1, 2008 11:11 AM
doesn't glycosylation require a sugar?
Posted by: alyoshapo | July 1, 2008 4:50 PM
This molecule was designed to have residual activity against broad-leaf weed species. The silage as feed wasn't "contaminated", the product was purposely sprayed on it. As many garden vegetables are broad-leafed, this residual activity stunts their growth a year after being applied to pasture and after passing through an animal's digestive system. Truly alarming!
Posted by: kirsten | July 2, 2008 6:25 AM
Glycosylation requires a sugar, which we have plenty of floating around our bodies. Wouldn't aminopyralid act as a Schiff Base, or would glycosylation occur through [something happening] at the carboxyl group? I'm more of a meathead than I am an organic chemist...
Posted by: Conor | July 2, 2008 4:24 PM
this is scary.
Posted by: bodydetox | July 5, 2008 5:28 AM
I am not a scientist but an organic gardener. Aminopyralid has turned up in our district of North Carolina in locally sold one year old manure/compost which is now showing the potential to wreak havoc on our local farms and gardens. Here's how it appears to have worked: You get a great yield of hay and straw with this Dow chemical “program”. You sell the straw and hay to local horse and cattle farms. The horses and cows eat the hay, and bed on the straw. You compost their manure and the straw bedding, let it cook for a year or so, and then sell it to compost packagers and vegetable gardeners. Our local extension service begins to get calls about twisted tomato vines with curly leaves, wilting eggplant, and droopy potato plants. Strawberry producers loose a season’s crop. Suburban gardeners report wilting zinnias. And then you suddenly realize that the herbicide was in the manure, and has now contaminated the soil.
I am looking for advice on effective soil remediation and any known or suspected impact on human health if we consume the crops that do not appear to be affected. Looking at the EPA statement (http://www.epa.gov/opprd001/factsheets/aminopyralid.pdf)says the following "Two field dissipation studies were performed (in California and Mississippi). The results indicate that aminopyralid is likely to be non-persistent and relatively immobile in the field. Half-lives of 32 and 20 days were determined, with minimal leaching below the 15 to 30 cm soil depth" which is clearly not the case.
Posted by: Kathryn Olive | May 15, 2009 8:41 AM