Recognize Signs of Urban Contamination

The first step to safely forage in Urban areas is knowing where to harvest. That means knowing the history of the land on which you want to forage, and what possible contaminants may be present. And so it is advised that an urban forager be mindful of the following considerations when choosing foraging spots; if you recognize any of the following red flags, be prepared to move on and forage elsewhere.

⇉ Lawns, Golf Courses, and Corporate landscapes may contain excess residual herbicides and pesticides.

⇉ Areas that were once heavily industrialized, such as tracts of abandoned land designated as brownfields by the US-EPA, may contain heavy metals like lead or other hazardous contaminants.

⇉ Old refuse and landfill sites, railroad tracks, and former gas station sites have potential heavy metal contamination. Areas along railroad tracks, in particular, are known to be high in Arsenic, which can be absorbed into plants.

⇉ Car and other vehicle traffic releases particulates from brake dust and exhaust along roadsides.

⇉ Factory Farms can be sources of excess nitrates, fertilizers, and manure runoff. The presence of manure adds a possible source of watershed contamination like E. Coli and Salmonella. Be particularly aware of this when you are considering plants that grow in wetlands or along a riverbed downstream from a farm.

⇉ Pharmaceutical companies, manufacturing, [the] furniture industry, and paint companies are all potential environmental polluters, especially of heavy metals. Water treatment facilities sometimes experience raw sewage overflows, contributing to E. Coli and Salmonella loads in [surrounding] waterways.

⇉ Power facilities may dump residual byproducts (including wastewater from the power-making process) into nearby waterways.

⇉ Public easements are often sprayed with herbicides to maintain clear access to powerlines and other municipal services. Usually there is no public notice when these easements are treated; however, it's easy to spot recent herbicidal treatment as it produces a brown area that looks like it's been burned.

⇉ Roadways are often treated in winter months with a salt or bromide solution, and increasingly popular is the use of fracking solution to desalinate the roads. All these cause plant material to appear burned and dead during the growing season.

⇉ Gray Water (wastewater) used in irrigation has a potential to host waterborne bacteria. Simply washing plants in the kitchen cannot eliminate pathogens like E. Coli and Salmonella.

The second step lies in understanding which plants are more likely to contain contaminants such as heavy metals or environmental pollutants in the first place, because every plant- and plant part- behaves differently; not all take up contamination in the same way. The key thing to remember is that any plant eatten for its mineral content can take up and synthesize heavy metals like lead. The flowers of an Elder Tree gathered from an urban park hedgerow will most likely have no significant concentration of heavy metals. But a plant like Curly or Yellow Dock, which is high in minerals, may well contain significant trace amounts of any heavy metal present in its environment.

Ultimately, if you have suspicions or are uncertain in any way about a specific spot, find another place.