Aged mulch is WAY BETTER for trees. It helps improve soil. It mimics forest floor perfectly. At least 5 feet wide, 3-4 inches thick is highly recommended. Make sure nothing touches the trunk though. The trees will thank you by growing more in the long run AND staying much healthier.

Numerous carcinogens have been found in artificial turf made from recyceld tires in New York City. If they are in synthetic turf there is no reason to doubt they are in these shredded tire mulches.

Where in the link does it say that there are numerous carcinogens in artificial turf? I found this statement "Some of those who oppose synthetic turf fear that the use of crumb rubber in the base, aside from posing an environmental challenge when it comes to disposal, could lead to the leaching of dangerous chemicals.21 Results thus far are inconclusive. " Can you please provide a link stating that rubber is a carcinogen.

Regarding the health hazards of using ground-up tires in recreational & garden settings, the report linked below seems sound and fairly well-documented to me. Note also the 'Related Literature' link on the right-hand side, with links to other studies, reports, and news stories.

All the best,
-Patrick

Here is a link that might be useful: EHHII Report

And if one goes further to the reference 21

#21 Chalker-Scott, Linda, PhD. "Rubber  The Reality." Ransfords Equestrian Surfaces. Retrieved April 2006

which takes you to a British commercial site extolling wood fibers of some kind over rubber crumbs for equestrian purposes. Now I bet there is absolutely no bias what so ever from them! (dripping sarcasm) I don't know the Chalker-Scott person from Adam (or should I say Eve). I do find it curious that an American wrote an article specifically for a U.K. audience complete with the British spelling of tyre. And I also noticed she referenced "one USDA researcher" but provided no footnotes to say who it is.

I too did not see the word carcinogen in the article (did I miss it?), perhaps another case of selective mis-quoting or the wrong link? I've noticed some people seem to do this a lot on the forums. :)

In one of the other related links in the article, there claimed a study was done that found some PAHs (polycyclic aromatic hydrocarbons) that they extracted with "organic solvents" (A category of solvents and grease-cutters of mostly synthetic origin (organic in this instance refers to their petroleum origins). All chemicals in this category are generally neurotoxins and nervous system depressants, especially if contacted in sufficient quantity.) Lots of that stuff kicking around NYC parks I bet. The heavy metals were extracted "by means of nitric acid with the aid of a high-efficiency microwave oven". Lesson: Don't soak the rubber mat in nitric acid and microwave it! Oh and that particular article listed a "William Crain, Ph.D., is professor of psychology at The City College of New York and president of Citizens for a Green Riverside Park" as the co-author. (My bold)

Give me a break. I could probably nuke the elastic band on my underwear and find something not good for me there! I would suspect that there are already billions of pounds of "tire dust" already in the environment from normal tire wear.

Lloyd

A quick note, for anyone reading this thread: I think Lloyd and I may have crossposted, and I believe Lloyd is responding to Kimmsr's link, not mine.

The reference "21" Lloyd quoted just above is to "Chalker-Scott, Linda, PhD. 'Rubber â The Reality.'" in the link Kimmsr provided. Not the EHHII report I linked.

Just trying to keep things clear, here. :)

All the best,
-Patrick

Thanks for all of the opinions posted.

Lloyd, thank you especially. Your post was well-written AND it made me laugh at the end.

Sorry Patrick, yes our posts did cross and I should have referenced my post to kimmsr's link better. I posted it and then ran out to coach youth bowling before checking.

I'm not saying there might not be issues with the tyre (Canada is part of the Commonwealth so I'll bow to the Queens language for now) crumble. I just am skeptical of some internet claims and studies.

Looking at the link that Patrick supplied, I read up on the methodology of that study and several things jumped out at me.

1) The study cost $2000. Seems kinda low to make a detailed study, but what do I know.
2) They mention about cooking the crumble to 60 degrees C. Seems pretty hot to me but I've never been to New York.
3) The water soak test. They soaked it in water for seven weeks! Once again biblical floods are common in New York?

In the California study I found this; the likelihood for noncancer health effects was calculated for a one-time ingestion of ten grams of tire shreds by a typical three-year-old child. Are we feeding this stuff to kids? At that point I stopped reading.

I am a grade 12 drop out so my knowledge of science is sketchy at best so my opinion is gut feeling only.

Lloyd

Understood on the skeptical part Lloyd -- and coaching kids is likely much better use of any of our time than posting here. :)

Two grand is cheap, but this is a report from a NP organization which is likely running on the backs of idealists and grad students, not a tobacco company report.

The heat issue might be a concern, but OTOH, like the watersoaking stuff, it could be an attempt to duplicate conditions over time. And especially with water, multiple occurrences of seven weeks of steady soaking at the base of a 4-6" non-decaying mulch, doesn't seem unreasonable to me over, say, a 5-10 year product life. The base of the wood chip mulch in my back yard is wet right now and I expect it to remain wet through into early May.

Young kids do eat what gets on their hands and faces, in playgrounds and back yards. If a child is going to a playground every weekday and clambering up and down the monkey bars and swing sets and slide, they'd pick up a lot of rubber dust over time. Dunno if it would add up to ten grams or not -- people who are (or have been) parents could answer that better than me. :)

My own formal science education isn't much above yours but my sense of the EHHII report was, it seemed more sound than most of what I've read (pro or con) on the subject.

All the best,
-Patrick

Hi Patrick, I agree the link you provided was much more reasonable and I am still reading the 147 pages of data from the California study that is linked within your link. (Huh? What did he just say? Never mind.)

I am not sure if I am reading it right, and it will have to wait til tomorrow, but I think it said at one point that yes, there are toxic properties and chemicals but they are below allowable safety standards (whatever that meant).

Surprisingly, I find this stuff interesting, they would have had to have held a gun to my head to have gotten me to read this in high school!.

Hey, that gives me a thought, I wonder if it's toxic to my wife's cats? Here kitty kitty.....

Just kidding folks, I LOVE these cats, really. (snort)

Lloyd

ROTFL! Lloyd, whatever you do... don't mention Cat Mulch Mats. ;)

All the best,
-Patrick
(I didn't say that, nope)

It suprises me not that there are people apparently totally unaware of the health hazards that rubber workers are exposed to, the carcinogens in the products they manufacture, and that these people would doubt that those same carcinogens would be present in shredded tires and that children are being exposed to these same carcinogens because far too many of us seem to believe that corporate America will not do this to us.
Apparently I copied and pasted the wrong link yesterday.

Here is a link that might be useful: Synthetic Turf.

ROTFLMAO, kimm, you crack me up. Yup, your latest link leads to the "microwaved rubber to extract the stuff" study co-authored by a psychology professor who is the president of Citizens for a green Riverside Park! At least you're entertaining.

Lloyd

If any of you had ever been to a junkyard, or maybe a farmers junkyard, you would change your tune. After a few years, nothing grows where the tires are stacked. I mean nothing. I know that it may take a while, but tires do break down and leach into the soil. I don't care about the case studies etc, etc. I have seen it with my own eyes. Now that the junkyard in question has been moved, the ground where the tires were 6 years after the clean up is still only allowing a few measly weeds to root and die.
Tires used for this is only man's way to try to disguise his need for greed as a way to "clean up the environment"
No bueno

I don't know enough to have a good opinion one way or the other on the safety of this stuff. However, that last study linked to is kind of goofy. They take the rubber and extract everything they have with organic solvents, nitric acid and they use a microwave in the process. It's not often that folks will be sloshing around in slurry of synthetic turf shreds, organic solvents and nitric acid, nor are synthetic turf fields commonly situated inside microwaves. And when they microwave the stuff, do the heat it to the point of melting? Who knows. They don't say. But if they do, they aren't just looking at what would be available on the surface of the material. They're pulling out everything that goes all the way to the center of each bit, when the vast majority of it would be locked up for hundreds of years because the stuff doesn't decompose. Then, they take numbers that in no way reflect the real-world exposure levels and compare them to allowable ambient levels in soil. Apples to oranges. That is a lot like measuring extractable arsenic levels in soil (and if you have soil, you have arsenic) and comparing those to allowable levels in drinking water. They're using over-the top numbers with no reference point. That's what's called "junk science".
But, I guess Dr. William Crain should know a thing or two about toxicity hazards in synthetic turf, what with being a psychologist and all.

Ah jeez Lloyd. You beat me to it while I was typing. I though it was my turn to be the curmudgeon today. We really gotta coordinate better.

If any of you had ever been to a junkyard, or maybe a farmers junkyard

Love going to the local re-cyclers junkyard, we get lots of materials from them, and you are right, nothing grows there. But they use Roundup and I think they used something called spike once to control any and all vegetation so that might not be what you are referencing to.

As for farmers, back in the old days I remember the old tires being burned, they weren't stored once they were useless. I think now our local dump takes them now and sells them to a re-cycler to make mats out of. :)

My Aunt has two of the large tractor tires at the end of her driveway that she filled with dirt and plants Geraniums or some such flowers into. IIRC the tires have been there at least 13 years, kinda pretty, the flowers grow nicely and the grass around them has to be trimmed. I'm pretty sure she doesn't microwave them but I could ask her. It won't be the last time I get that "my nephew the idiot look".

Lloyd

Hi squonnk, curmudgeon? Is that what I am! Kinda like the sound of that. Beats Goofy, which is what the kids at bowling call me. I wonder if I can get them to call me Mr. Curmudgeon?

Once, an instructor in my met class called me lackadaisical, I was pretty good at met, so thinking it was a compliment, said thank you, when I looked the word up later, I realized why he turned so red! oops.

Lloyd

Being a curmudgeon is great. I use to paint and play cello but this is way more fun.

By the way, I am insanely jealous of your gazeebo/office. (The cherries look good too.)

From Mirriam-Webster online dictionary:

Curmudgeon - a crusty, ill-tempered, and usually old man.

I ain't old!

Lloyd

heh heh

Why would anyone want rubber mat around the trees? It will never improve the soil like wood mulch does. Look at the forest floor... Rubber mat will never achieve that...

texas grrl, have these guys talked you out of the rubber mat? ;-)

Your trees will much appreciate a 3 to 5 inch layer of bark chips, composted wood chips, pine straw, etc. For the trees' benefit, make the mulched area as large as possible....think in terms of root system, not tree trunk!

Why would anyone want rubber mat around the trees? It will never improve the soil like wood mulch does. Look at the forest floor... Rubber mat will never achieve that...

Uh, Lou, I think texas gal wants to prevent growth around the trunk of the tree for aesthetic reasons. I could be wrong though but that what these mats are advertised to do.

I've seen them on some peoples lawns, look okay from the street.

Lloyd

Based on the links posted by some of the Mulch Mat opponents, I have decided to use them. I don't plan to microwave them so I think I'll be ok.

But as I have said in other posts, I am new to gardening. If I start to see ill effects on the surrounding grass, I will certainly report my findings here on Garden Web.

WTG texas grrl, for making choices good for your situation.
However.
Wait till the Texas summer, just as good as a microwave.
I still like the idea of coir mats, so mowing is easier.

Tires today are not made of rubber, they are all a synthetic material, hazardous materaisl at that. Tires have not been made of rubber since shortly after WWII when get enough of the latex from the trees became difficult.

Trees will hate you for rubber mats.... Have fun.

There's a word for that, attributing human feelings to non human things. Anthropomorphizing, yea, that's it.

When the trees either sign my paycheck or become any part of the IRS at all, I will worry about whether they don't like me.

I like trees, really I do. But when I had to cut one down last year, I didn't say a Hail Mary or anything. Did plant another, though.

Hi texas_grrl, I apologize for my part in hijacking your thread, I hope we at least entertained you somewhat. I noticed you said you did not plan to microwave the mats, I feel that it is important to point out that according to that one study, it might be okay to microwave those mats, as long as you used a low-efficiency microwave versus a high-efficiency microwave and refrained from soaking them in nitric acid first.

All kidding aside for a second, good luck with your yard, post some pictures if you are able and please keep us informed as to your results. (good, bad or indifferent)

Lloyd the Curmudgeon

P.S. Back to kidding for a second, give your trees a hug, they'll love you for it! lucille has the right idea.

It is totally amazing to me that people will accept without question information supplied by the manufacturer of a product as being valid bit will totally reject information from an independant source as totally invalid.

kimmsr
I can't say anything about your "questioning information supplied by the manufacturer.." statement, because I haven't accepted or rejected any of their claims.
However, you site an "independent source" as though it's valid by virtue of its independence. First of all, it's not really an independent source. As Lloyd pointed out, the psychology professor pushing for, and participating in, that study was the president of Citizens for a green Riverside Park. That position and his sense of responsibility to protect people (though well founded and I respect him for that), put him too close to the subject to be considered "independent". He did not make the synthetic turf, but he had a vested interest in the outcome of the study that he and his friend conducted.
Second, independence does not equal validity. A poorly designed and executed independent study can be just as misleading as any study funded by a private entity.
The study you quoted was neither independent nor valid. It was a poorly designed study with only two replicants and no statistical analysis of the very meager data gathered. Even between the two samples collected, the results from sample 1 to sample 2 varied by as much as 75.6%. (namely "enzo(k)fluoranthene.. 7.29 ............ 1.78). Those numbers are shockingly useless in regards to reaching conclusions of any significance without copious replication and repeatability.
Also consider, as stated above, that they extracted amounts of chemicals that one would never encounter in the real world and compared them to values of the same chemicals but in an entirely different matrix. (namely, in soil) And the study doesn't event mention if that is extractable in soil, or what is immediately available, etc.
It was an atrocious study that proved absolutely nothing and was designed for the sole purpose of creating an emotional response to sway opinion towards the psychologist's view concerning whether or not synthetic turf should be used in the park that he was responsible for. Again, "junk science". That is why I at least, rejected it as totally invalid.
I am amazed that you place any confidence in that study at all. Amazed, but not surprised. You tend to collect "studies" that support your claims but are of little, if any, value. You talk about ideas that are supported by "solid scientific research" but based on this and other instances, I have serious misgivings concerning your capacity to determine what is and what is not "solid scientific research". You can believe anything you want, but you shouldn't assume that you're right and everyone else is wrong because their studies conflict with yours until you get a much better handle on what is and what is not good research.

Squonnk-

Good analysis and kudos to you for taking the time to check facts and really look at what was being presented.
Just as an observation, some of the forums on this site set a collaborative tone, and some are adversarial. It seems that here, people tend to get down and dirty; perhaps that is appropriate for a soil forum.

"people tend to get down and dirty; perhaps that is appropriate for a soil forum."

Hah, well played. But you know, I have a theory on that. Of all the topics given their own forum at GardenWeb, I believe soil is probably one of the most technical. For that reason, I think it attracts folks of a more academic bent. You put a bunch of academics in one room and they'll either save the world, kill each other or both.
Either that or I just don't play well with others. Yeah, probably the second one.

I think if someone in a state somewhere very far from mine is willing to take my old tires, I should keep my mouth shut.

You know you can get that mulch in Caribbean Blue?

I'm feeling bad now. I've got a good friend in Texas.

"Summary and conclusions

The Connecticut Agricultural Experiment Station study conclusively demonstrates that the tire crumbs and tire mulch release chemical compounds into the air and ground water. Thus, tire crumbs constitute a chemical exposure for humans and the environment.

It is clear that the recycled rubber crumbs are not inert, nor is a high-temperature or severe solvent extraction needed to release metals, volatile organic compounds, or semi-volatile organic compounds. The release of airborne chemicals and dust is wellestablished by the current information. The Connecticut Agricultural Experiment Station research conclusively demonstrates that release can occur under ambient conditions experienced in the summer in Connecticut.

Those published health assessments that indicate de minimis risk should not be applied to the synthetic turf paradigm and may not be appropriate for playgrounds with open layers of recycled tire crumbs.

Health endpoints of concern are numerous, including acute irritation of the lungs, skin, and eyes, and chronic irritation of the lung, skin, and eyes. Knowledge is somewhat limited about the effects of semi-volatile chemicals on the kidney, endocrine system, nervous system, cardio vascular system, immune system, developmental effects and the potential to induce cancers.

There are still data gaps that need to be filled in and additional studies are warranted.

It is prudent to conclude that there will be human exposures to chemicals released during the use of synthetic turf fields.

The excess amount of zinc in the rubber tire mulch makes it unacceptable to be used in gardens."

Here is a link that might be useful: Tire mulch

annpat
Now you're talkin'. That's something worth reading. Of particular interest are the full text report along with studies that it references. Thanks for the link.

Annpat-

Please don't feel bad. I think what we are getting at here, some of us, is that it is worthwhile to have solid info and a vigorous interplay of ideas prior to making a decision.
You already know I plan to use coir, and I think for me that is a good and studied choice, but I do not purport to say that what I like, everyone must like.
You provided good info and I thank you.

It's tough to beat what sqounnk said, IMO, he is a VoR on this forum.

The link annpat gave is the same one patrick gave earlier on. A much better study than the one kimmsr gave. But I still have problems with it as outlined earlier.

Is there stuff in tires and tire by-products that could be hazardous? I think so.

Does hazardous stuff wear off tires during normal use and get into the air, soil and water? I think so.

When we drive on a road or walk near one are we breathing in the dust from tires? I think so.

Would a person get sick eating tires or parts of tires? I think so.

Do any of these studies prove everything conclusively? Not a chance and even most of the good science ones admit that more studies are necessary.

Should we be careful using any one study to make absolute conclusive statements? I think so.

Should we expect not to be challenged when we make ludicrous statements? No way!

It is totally amazing to me that people will accept without question information supplied by the manufacturer of a product...

Where did you get this from? Who has accepted any information supplied by a manufacturer? Has anyone linked to one? Has anyone looked at one?

Lloyd the (young) Curmudgeon

Tires today are not made of rubber, they are all a synthetic material, hazardous materaisl at that. Tires have not been made of rubber since shortly after WWII when get enough of the latex from the trees became difficult.

Well the more I look into this the more I have come to the realization that some posts are almost completely false.

2. Typical Composition by Weight

This lists the major classes of materials used to manufacture tires by the percentage of the total weight of the finished tire that each material class represents.

Passenger Tire

Natural rubber 14 %
Synthetic rubber 27%
Carbon black 28%
Steel 14 - 15%
Fabric, fillers, accelerators, antiozonants, etc. 16 - 17%
Average weight: New 25 lbs, Scrap 20 lbs.

Lloyd the skeptical curmudgeon

Here is a link that might be useful: Rubber Manufacturers Association

lucille, I got confused. I thought you were going with the tire stuff. Good choice with the coir. Thanks for being a good sport. I almost asked if I could send you all our cigarette filters. I'm glad I didn't. I'd be ashamed now if I had.

So Lloyd where do they get "Natural" rubber from? How many trees are there in the world that can supply the sap needed to make that many tires?

Apparently they get natural rubber mostly from Asia:

http://en.wikipedia.org/wiki/Rubber

I realize the question was directed to His Royal Curmudeonliness and I expect he will come up with an answer, but I was curious enough to look around a little when I saw the question.

Kimm, one of the first steps for getting out of a hole is to stop digging. LOL

Lloyd HRC (thanks lucille)

one of the first steps for getting out of a hole is to stop digging.

How apropos.

You'd think on a gardening forum people would know about holes and digging.

When people aren't clawing one another's eyes out here, this place can be downright entertaining. And every group needs a Lloyd for comic relief. I almost choked when I read about the toxic underwear.....

Karen

I saw these mats at Wally World last year and just didnt like the appearance,feel or smell of them. They were thick and stiff and oogaly and I couldnt see them molding themselves to the "terrain". My yard isnt flat like they are so I just let them go regardless of the toxin issue.

:)

I have about 10 of those mulch mats. My young trees are doing much better with those mulch mats in place. I recommend them based on my experience. They supress/kill the grass and weeds and they're easy to mow around.

I'm getting mulch mats to go around fake silk trees and doing the rest of the yard in that short green nylon grass carpet stuff.

(ducks quickly)

This was fun read, sorry I missed when it was happening.
squonnk, just a thought, "You put a bunch of academics in one room and they'll either save the world, kill each other or both." If there are enough academics in the room and they kill each other, that could save the world, or give it a fighting chance. Thanks to kimmsr for the straight lines for the others to play off. thanks to the person in ID who likes the mats and isn't afraid to say so. Thanks to Lloyd for aunt's rubber tire planter example. j

Bumping due to tire/rubber discussion in another thread.