Expert: George Maxwell - 12/16/2007

Question
My son has a roommate who owns two chihuahuas, neither of which is house-trained. He called me today and told me when he was sauteeing onions for dinner he created tear gas. The only thing I could think of was the volatile oils from the onions combined with the stench of dog urine to create the "tear gas". I haven't been able to find anything online regarding this and I am hoping you can shed some light on this for me as I think my son is living in a highly toxic envirnoment and want expert proof to show him. Thanks

Answer
Thank you for your (highly original) question.

I think it's probable that the "tear gas" was simply from the onion. Onions contain sulfur-based compounds in the root nodules, and when you chop and heat the vegetable, these compounds are released. When they hit the surface of the eye, they dissolve in the moisture there to make very dilute sulfuric acid; the eyes water as the  body's response to get rid of the irritating fluid.

Urine contains a number of nitogen compounds, which can break down to form the toxic gas ammonia. However, it's unlikely that your two canine friends could produce enough ammonia to be dangerous - indeed, being an alkaline gas, ammonia may help to neutralise the acidic onion vapours.

Perhaps, during their house-training, you coud put the litter tray in the corner of the kitchen, in the hope that the dogs counteract the onion. Admittedly, this may introduce a biological health-hazard, but this is likely to be minimal compared to the danger of inadvertently creating chemical weapons from root vegetables.

All the very best to you, your son and the dogs. Have a very happy holiday season.