FAQs
Q: How concerned should I be about pollutants, heavy metals, pesticides & dog pee when I’m foraging?
A: It depends. Most people are overly cautious about collecting wild plants, particularly in urban settings. According to a 2019 study from the Berkeley Food Institute, common weedy leafy-green edibles were found to possess negligible if any levels of pesticides & heavy metals, meaning they are perfectly fit for eating (click here to read the details). The study was conducted in urban areas with a history of pollution around the San Francisco Bay Area.
While this study is promising, we certainly need more data points in this area of study, which has hardly been researched. I urge you to use your senses and best judgement when collecting wild plants. Ask yourself: do they look healthy? Smell healthy? Feel healthy? The best method is to know your collection areas in order to be confident pesticides are not being sprayed in that area and have a general sense of the happenings in that place.
To put this in perspective, a lot of fruits & veggies (even organic brands) that you buy at Whole Foods are grown near roadways. If you ever drive through the Central Valley of California, where at least 40% of the nation’s fruit & veggies are grown, you will see the horrendous conditions of the modern agricultural system. Add to this, that these foods are then often wrapped in plastic and shipped very long distances. The only real way to get optimally clean food is to forage & grow it yourself or have an intimate connection with local growers, hopefully both if possible.
As for dog pee, just wash your harvest and consider collecting a few feet from the sidewalk. It’s the least of your concerns honestly.
Q: I’ve heard certain plants bioaccumulate pollution, such as nettle, horsetail, Japanese knotweed, etc. How concerned should I be?
A: So the plants catalogued in the above BFI study are mainly annual species of leafy greens. There is special consideration to be given to perennial wild edibles growing in polluted soil. Plants like nettle (Urtica spp.), horsetail (Equisetum spp.) & knotweed (Reynoutria spp.) are commonly used wild plants. They spread rhizomatically (their roots move underground to form clonal plant colonies) and are perennial, meaning they live for many years. These plants have been shown to accumulate heavy metals and other common pollutants in settings where these contaminants are in high concentrations. It may be wise to collect them from more remote locations.
Q: What about collecting fruits in cities?
A: There are a couple of studies on this subject (click here for the Boston study). To paraphrase, fruits & seeds are the safest part of the plant to collect in a city. While the roots, and upper portions of the tree can collect contaminants from the soil, the fruits are generally considered to be clean according to these studies. I’ve personally collected hundreds (if not thousands) of pounds of fruit from very urban areas without concern. The secret is that this fruit is not only safe to consume, but generally higher in micronutrients that its store bought counterparts. I do recommend washing fruit from these areas usually, because it can be covered in brake dust, engine exhaust, etc.
