There are warnings about eating food grown in the danger zones in Portland near glass factories. I live near one. Can I smoke the weed I grew in my backyard last summer?

—Urban Farmer

Having nearly been purged in the Great Fluoride Program of 2014 (aka Crestallnacht), I'm reluctant to wade too deeply into any new mineral-based civic controversies, but what the hell. #yolo

First, the bad news: Contamination of cannabis with toxic metals like lead and arsenic is a real thing. In fact, heshers who Google "marijuana" and "heavy metal" in hopes of learning which strains are the dankest to shred on will find that the whole first page of results is about, like, cadmium and shit. (All osmium, no Ozzy.)

It gets worse! Cannabis, in keeping with its identity as the Earth First! activist of the plant world, actually goes out of its way to pull toxins from the earth. Industrial hemp has even been planted near Chernobyl for the express purpose of reducing soil toxicity.

Northeast Portland, however—imperfect though it may be—is no Chernobyl. "It's unlikely that cannabis grown in the Portland metro area could contain enough metals to significantly affect the health of people who consume cannabis," says Dr. David Farrer, toxicologist with the Oregon Public Health Division's environmental public health section.

It's not that hot-spot soil is particularly wholesome—vegetables grown in it are still iffy. It's just that, Willie Nelson notwithstanding, people don't consume that much weed.

An 8-ounce tomato is a light snack. Eight ounces of weed is 200 pretty fat joints. Even if your weed is the schwaggiest schwag that ever schwagged, you're not going to put away anything like the same amount of homegrown ganja as you would homegrown zucchini.

Of course, there's always going to be the homeopathic crowd for whom even a single atom of contamination is too much. If that's you, then yes, stop smoking weed—you're paranoid enough as it is.

Have a question about life in Portland? Send it to dr.know@wweek.com.