Modern foraging requires vigilance. Beyond avoiding animal waste, soil health is crucial. Past land use can introduce contaminants like heavy metals and pesticides into our food chain. Understanding local history is vital for safe foraging.
In my last essay, I covered the importance of being aware of animal mess.
Today, we need to discuss soil health.
There is a common misconception that people ate organic food before World War II because pesticides were not invented.
While this is true up to a point, the period before the Industrial Revolution was when the nation’s food was at its cleanest.
Potentially toxic pesticides started being introduced into the food system in the early 1800s with the invention of arsenic, copper, nicotine sulfate, and pyrethrum-based compounds.
Just as humans uptake what is in the food they eat.
Likewise, plants take not only nutrients from the soil but also pollutants.
As a result, you need to be aware of the history of the places and spaces where you gather.
Land has a story, and it is up to you to take responsibility and learn the history of your local area.
That park you gather in, what is its story, its history?
Foraging covers many disciplines, and one of those disciplines is studying local history.
I hated history at school. Being a parrot and regurgitating facts and figures by rote left me cold.
So when my first plant mentor, Marcus Harrison, insisted I find out the history of the soil around where I lived, I nearly jacked it all in.
I said to him, ‘Marcus, are you saying I have to become a flipping historian?’
He replied, ‘You do if you plan to forage regularly. Maybe not if all you want do is tinker around the edges, or gather a few bunches of wild garlic, or a punnet of blackberries once a year. But if you want to become a proficient forager, you had better do as you’re told.’
Never one for mincing his words was our Marcus!
So, it is crucial to investigate the history of your local soil to understand the risks associated with soil contamination.
Local resources such as libraries, county record offices, and local history societies can provide valuable information about past land uses that may have affected soil quality.
Historical maps, trade directories, and records from environmental agencies can help identify potential sources of contamination.
One of the primary concerns is the presence of heavy metals in the soil.
Most countries have banned leaded petrol since the early 2000s. However, industrial activities, fertiliser applications, vehicle tyres and brake powder still introduce heavy metals like cadmium into urban soils.
Studies have shown that heavy metal concentrations are typically highest in roots, followed by leaves, and lowest in fruits.
To minimise exposure, you should investigate site history, test soil for common contaminants if concerned, and avoid foraging near industrial sites or areas with a history of heavy industry or waste disposal.
Another hidden danger is the presence of herbicides and pesticides.
In the UK, authorities spray streets with herbicides, particularly glyphosate, multiple times yearly.
Consuming plants exposed to herbicides, especially those growing near pavements, can harm long-term health.
To reduce the risk of exposure, you should avoid collecting plants near pavements or areas likely to be treated with herbicides, wash and cook foraged plants thoroughly before consumption, and be aware of potential pesticide use in city gardens.
Polycyclic aromatic hydrocarbons (PAHs) in car exhaust fumes, burning stoves, and asphalt can disrupt metabolism and be carcinogenic.
So, to minimise the risk, always wash and cook foraged plants, even if they are out of reach of dogs.
You must carefully select your foraging sites to minimise your exposure to contaminants.
Also, realise that your allotment-grown and farmed plants are potentially contaminated with these substances.
So, it is not only foraged plants. It’s all plants that you eat!
On the one hand, that’s scary to realise, but on the other hand, what I am teaching you will help minimise your exposure to pollutants.
A study from São Paulo, Brazil, found that plants growing along motorways and busy roads accumulated significantly higher levels of toxic elements compared to the same species collected from parks and quiet streets.
You should stick to low-traffic areas and quiet streets and stay 50 metres from major roadways.
Fruits with rough, fluffy, or hairy surfaces, such as the fruits of staghorn sumac (Rhus typhina), should be consumed only directly after maturing, as they can absorb dust and chemicals from the surface more quickly than smooth-surfaced fruits.
In my next email, I’ll cover runoffs, rivers, and an important gathering protocol you should pay attention to.
Talk soon,

P.S. Plant lovers: Since 2008, I’ve shared foraging knowledge freely, supported solely by people like you. No ads, no paywalls – just honest plant education.