Urban/wilderness foraging & Potency of medicinal herbs

I’m fairly new to foraging and I’m curious if location could have an impact on the potency of medicinal herbs.

For example could a history of commercial agriculture, mining operations, or even suburban developments lead to significant variations in toxicity? Heavy metal content and bioavailable vitamins and minerals are variables that I think could be vulnerable. Wild plants in areas like these could be purposely sprayed with pesticides and/or herbicides, or accidentally exposed to them after a windy day. I wonder if chemicals like these remain in the soil even after a few years time? And if so, could the plants that begin to grow there be impacted? Is there risk in foraging plants in a now forested area that was a trash dump for ten years?

Basically I’m curious if anyone has compared the effectiveness of foraged medicinal herbs or fungi growing in urban areas/nearby commercial agriculture to that of foraged herbs growing in the wild of forests/meadows, etc. Or if anyone has researched this and knows if contamination can alter a plants’ growth significantly enough to make an otherwise highly beneficial herb potentially useless?

I hope I didn’t make this sound super confusing lol, but if I did I’m sorry. I’ve been thinking on this subject for a while so I’m curious to hear any thoughts y’all have on topics of a similar vein 🌿

Some plants are shown to accumulate toxins while others are good at not absorbing them - most of the research I see is on heavy metals it seems, but research on other toxins too. Many species of plants have been successful in absorbing contaminants such as lead, cadmium, chromium, arsenic, and various radionuclides from soils. They are being  used a little for phytoremediation of soils by some people.

From a research article: " Plant roots take up metal contaminants and/or excess nutrients from growth substrates through rhizofiltration (=root) process, the adsorption, or, precipitation onto plant roots or absorption into the roots of contaminants that are in solution surrounding the root zone. This process is for metals, excess nutrients, and radionuclide contaminants in groundwater, surface water, and wastewater medium. "https://www.hindawi.com/journals/ijce/2011/939161/

For instance, I know that the herb Mullein scavenges chromium, lead, nickel and zinc from the soil. The ancient tree Ginkgo is known for cleaning the air. I have not seen the research on this, but it seems to be a common idea and I am not sure where it comes from. I know that the plant extract put into toxic mediums where they are trying to grow other plants has shown a protective ability for those plants and allows them to grow more normally in the toxic milieu. If you find research on Ginkgo cleaning toxins out of the air let me know. From the research I have seen it is all in petri dishes and I am looking for data on a live tree.

Plants are able to process some toxins into other things. They do this with mycotoxins similar to how we process mycotoxins. They have biotransformation systems also. Researchers claim the plants can take complex organic molecules that are degraded into simpler molecule contaminants in soils, sediments, sludges, and groundwater medium. So, there is apparently some biotransformation of other toxins (I know more about mycotoxins), but I am not sure how much. They can alter metals through  conjugation, but I don't know if that conjugated material is excreted somehow or they simply store it. If we eat that plant, our body could unconjugate that same metal making it easier to absorb in our body. Some metals such as zinc in small quantities would be fine, but we don't want lead or mercury. The researchers state that they think amino acids like proline are probably involved in metal chelation of plants. We have proline in our saliva by the way. Ruminants have way more of it in theirs. Goats have a lot. Besides proline binding metals it also binds tannins in herbs and allows goats to eat more tannic foods. It is also thought that glutathione could be used by plants just as we use it to bind metals and other toxins (glutathione conjugation). https://youarethehealer.org/health-conditions/optizmize-your-health/detox-biotransformation-pathways/glutathione-conjugation/ A lot of sulfur containing proteins such as cysteine can bind different metals and may be involved the same as we use many sulfur containing molecules to bind heavy metals in our bodies.

There is some very involved, tedious research out there on this topic, but I have not read much of it. Perhaps someone else has. These are just a few thoughts I have.

Oh yes, regarding the herbicides on the land. Many of them chelate or bind with minerals in the soil. Glyphosate is a great example. Monsanto said for years that it was safe and disappeared into nothingness quickly. Well, in reality it was binding with minerals in the soil, making the minerals less available and one of the ways it kills plants (making the minerals unavailable to the plant). So, now we know that it is there for an unknown amount of time. Perhaps we should send Bayer-Monsanto a bill for remediating the worlds soil.

Oh, I should have added that there are some great remedation projects going on with cleaning up waste by using plants. Some are small scale on peoples farms but some are larger scale like the waste-water project that is on-going at the Oregon Garden. https://www.oregongarden.org/ I could not find data about it on their site, but last time I went there, one of the employees there explained the project in detail to  me.

Mother Earth News is hosting some fairs this year. One is in Texas, another is I think being hosted by Joel Salatin? Anyway, if you look into that, there is a class being offered at the Texas one by the "Dirt Doctor." I do not remember his actual name, but the talk is about soil health and detox for the sake of growing medicinal and edible plants. He'd probably be a good start for resources.

Many traditional herbal healing communities would insist that plants of the same species growing in different areas will have different properties. These folks rely, often, on having a personal relationship with the plants so that you can ask them which communities would be best at helping your particular problem.
I don't know how this knowledge translates from that heart centered (and gut accented) knowledge base into our cerebral only knowledge form but I would imagine that you would find different levels of active alkaloids in different growing conditions. Many of the medicinal compounds we find in plants are made.to combat specific stressors so it stands to reason that plants dealing with different types.of stress will produce a different suite of active compunds

I agree with potential toxicity in compromised sites.  As for the other part of your question, it is a long held belief that the most potent herbs grow in harsh environments.  I do not know if this folk wisdom is universally true  But, medicinal herbs and wild edibles growing... for instance... out of a mostly bare stone, windswept mountain outcropping are believed to be most nutrient dense and/or potent. Similar beliefs are held about dense swamps and dark woods and desserts.  Anywhere the plant grows lowly and struggles to survive.  That said, could you grow even more nutrient dense, potent plants in very rich "better than organic' polyculture systems?  I don't know.  It would be well worth experimenting.

To increase the potency, neglect the plants. let it suffer drought, insect attacks and such.
Then let it go to seed, only the strongest of the bunch will sprout and survive.
Cull some of the bland tasting ones. Then let them go to seed and sprout again.

I find that 'neglected plants both in urban empty lots/ concrete jungle and forest area is more potent than babied, artificially fertilized crops that a grown and selected for looks and ship-ability.

Now in urban area, we will find that there is elevated levels of heavy metal, and the plants will accumulate them and its ends up being bad for us.
I will probably eat 8lbs of lettuce in a week, but only 1/128th or 1 ounce of thyme per week. 1 week of heavy metal lettuce is equal to 2.5yrs of heavy metal thyme. So I would much rather take my changes with herbs over bulk vegetables or mudhroom.
In fact mushrooms fruiting bodies are hyper accumulators of heavy metal. So I don't like eating mushroom from city woods.

As for pesticide, I am not too sure how they affect the potency.

The EPA's website has a large database of info, though I don't know how dependable it is on all counts.  (I've wondered since reading - Duluth Tribune in particular - about endangered species being made unendangered where pipelines and fracking are approved :( )  

There is also the Goodguide website which can be used as a springboard for learning about pollution of different kinds in areas that report findings.  Enter a zipcode to find superfund sites, how one place compares to another, and which businesses contribute how much toxic gick to air, water, and soil.  I was shocked to learn that Lake Superior had 16 superfund sites while hearing locals say it is and always has been pristine.  Not only that, but I lived at the worst superfund site with the ore dock in Ashland, Wisconsin.

http://scorecard.goodguide.com/

After that, I research individual plants of interest to learn how they work.  I also read that the typical waiting times (3 years is commonly stated) for heavy metals and other contaminants to become significantly mitigated is not 100% reliable.  Cattails, as one example, in places like retaining ponds where there is no through current or other exchange of toxic gick water for good water, might continue to hold contaminants until the water is somehow cleansed and replenished.

Hello,my name is Wes and I’m new to the forum.I grew up in Alabama and come from a family of Farmers.We raised cattle and grew gardens for many generations.We often sprayed the fields for weeds in order to raise thick and healthy Bermuda to bail for our cattle.Little did I know that one of the so called weeds was actually “Dill”.This is funny to me now because my wife is from Trinidad and we now grow this same plant in our back yard for her to cook with as were herbalist in a sense.So to now catch up with the post...I’m not familiar with the affects that different pollutants have on the natural herbs that surround us but I’ve been very fascinated with exploring and searching them out.For me,I try and stay away from any areas that have been treated with herbicides and chemicals such as the edges of ponds or commercial cites where a lot of construction has taken place..I recently came across a book that has mostly all of the natural herbs,plants,and trees in North America.We are experimenting with several of them as we use many for medicine and rich nutrients..There are many nice photos that help us ensure we’re not eating something poisonous.Anyways I’ll leave a link below incase anyone is interested..  https://6b57f9jvg1a9l8tavewmpegj9u.hop.clickbank.net/?tid=BEACHVIBES777

I personally wouldn't use a book to identify and eat mushroom or plants in the hemlock/carrot/dill family and likewise for the nightshade family. Now for the mint/thyme family, garlic family and aster/sunflower family, I would be okay with risking it, due to the low odds of poisonous look alike. Others with more experience can easily tell the difference between edible wild mushroom and dangerous look alike.