Are urban logs a safe substrate?

I find plenty of logs freshly cut every spring in the city. Wondering if anyone knows of any studies, etc. citing the risks of toxins in the wood of urban trees. I'm sure there are some, but would it be too much of a risk? All the wood I wood consider using is from residential, not industrial areas. Hence, the most common pollutants I'm thinking of is exhaust from traffic( looking for younger trees planted post 70's so no leaded gas), lead paint from houses(I pick trees from houses w/ brick exterior, no paint), and whatever chemicals people may be dumping/ spraying on their property. If anyone has any resources or knowledge I would love to hear. Thanks!

hey there, as someone who is tempted by 4-5 pound flushes of reishi off stumps here in brooklyn i would not recommend it. fungi concentrate metals in their mushrooms. they are so effective that some people (myself included) see them as keystone species but not necessarily a food source. the book below cites dozens of studies that show mycorrhizal and saprophytic fungi being able to break toxic compound bonds and filter heavy metals. one of the studies noted dead mycelium is also greatly effective in filtration.

if you can get to a library and jump on proquest dissertations database you will be able to pick through the most recent studies showing where and to what degree different trees uptake metals and other contaminants, via airborn exposure and from the soil (lead doesn't move and is all over the topsoil from decades back). an interweb search will offer a lot of abstracts too. i love foraging food too but this is one area that city-goers should be cautious with.

readings and other sources
Harbhajan Singh: Mycoremediation: Fungal Bioremediation
http://link.springer.com/chapter/10.1007/978-3-642-23327-2_18#page-1
http://www.ijpbs.com/ijpbsadmin/upload/ijpbs_50cdc71f58d76.pdf
http://link.springer.com/article/10.1007/BF02817647#page-1



instead of leaving the post with warning, let's talk alternatives briefly. i've collected coffee grounds from cafes in the neighborhoods around me. most places have been happy help. i bring them a couple clean empty buckets with lids and they give me the full ones. this material, if fresh, has also been exposed to hot water which will have helped in pushing back competing fungi. i also get sacks of roasted cacao beans and hulls and old coffee beans from fancy chocolate and roasting businesses. and if there are wood workers in your city many artisans get untreated cured lumber so their saw dust and trimmings are fair game too.

Thanks for the references! I'll have to do my research w/ them and look a little closer at the areas I gather from.I'm not anywhere as populated as Brooklyn, but who wants to take chances! I'm glad you mentioned the coffee grounds as that opens another question I have w/ urban mycology. I gather regular, not decaffeinated, coffee grounds for oyster cultivation. I steer clear of decaffeinated because of concerns about chemicals used in the decaffination process. I also wonder about the presence of pesticides as the grounds I get aren't organic. Any insight into either of those topics? Thanks again for the links.

I have also been tempted. There have been some studies on car exhaust pollution and health effects on people. The conclusion of the one that I saw was basically if you are within 400 feet of a freeway, don't eat the food. Also don't live there. There are cars almost everywhere, but the concentration of pollutants near a freeway is too high.
John S
PDX OR

I know that they use oyster mushrooms growing in I think hair? to clean up oil spills now and I have heard that the mushrooms change the oil and as a result the mushrooms themselves would be totally safe to eat. The video I heard that on they said no one actually eats them because the idea of it is too disturbing but that scientifically examining the mushrooms they seem to be totally safe.

this is not the video I saw before but this one is pretty amazing

casey lem wrote:....I steer clear of decaffeinated because of concerns about chemicals used in the decaffination process. I also wonder about the presence of pesticides as the grounds I get aren't organic. Any insight into either of those topics? Thanks again for the links.

Many apologies for not getting back. There's only so much we can do in some respects. Just because something is grown under organic certification (which is often only moderately more responsible ecologically in my opinion) doesn't mean there are many nutrients in the food, nor are there any assurances that with each change of hands in the shuffle globally this material is being tampered to maintain weight, color, and so on.

What we do know is the process for grounds to go through before it hits the machines. Agricultural -icides will undoubtedly break down into other toxic compounds in the drying process, then storage, and then roasting. Especially through percolation (which encompasses every cafe machine I've ever seen), much of the soluble material is lifted from the grounds. What remains on the grounds when they come to you is broken down into far simpler and perhaps less or (maybe) non-toxic compounds by the enzymes the oysters exude. What we should be a little concerned about are metals, as these are toxic at their base form and fruiting fungi have been shown to accumulate them into their mushrooms. If you are curious to see what you are working with you can drop off samples to a local lab. I use the services offered by a community college soil science department, but your local cooperative extension will be able to reference some options in your area.

If you do take any samples over, please post your findings!