Your attitude fails the test of logic. And your responses are not
scientific but attitude and opinion.

Strawberries bought in the stores come in tar paper pots and bearing
fruit. So according to John a buyer who eats that strawberry is taking
extra risks.

My priority is the health of my plants. And when I see them spurting in
new growth after I apply roof shingle mulch. For me that says it all.
If my plants are healthier and excelling in growth, I have no fear of
their fruit.

If a research turns up facts that indicate tar roof shingles have more
mercury or more lead or other toxin than ambient environment then I
would be concerned. But there is no study that outlines the internal
content of asphalt roof shingles.

As John mentions that pitch is commonly used in fruit orchards to mend
old trees. And that the vapors on asphalt highways gives us more
contact with pitch than however little a plant could absorb and pass
on.

If people make roof shingles and apply them to their homes, then
commonsense should tell people like John, that if they are safe as a
roof on your house, then commonsense says they are safe as a mulch for
a plant in your yard or garden. In fact, some roofs across the USA are
cleaner and able to eat off of than the kitchen tables and dishes of
many homes in the USA. But of course John does not have a high order
peak of commonsense.

Another example that John mentions is the breathing of the vapors of
asphalt roads. I did warn in my posts that I would not use those old
shingles that contain asbestos. What year did they discontinue asbestos
roof shingles? The fear here is that as the roof shingles decay into
the soil that the old asbestos remains present in the environment. I
would not use asbestos content shingles but dispose of as the current
health regulations dictate. And I would not use the new shingles that
are treated with biocides such as the moss and fungus of Northwest
regions. But the analogy of asphalt vapors that John mentions is
analogous to asbestos in the old shingles. People get more asbestos
into their bodies from the roads and highways because the brakes of old
vehicles still have asbestos brake pads. So a typical human gets more
asbestos in their lungs from breathing near roads and highways such as
New York City than they get from most any other source.

Summary: I see my plants thriving with tar roof shingle mulch and so I
am happy to use them for mulch. As to whether these roof shingles give
those plants toxins is dubitable because plants do not intake chemicals
such as lead or mercury. And it is dubitable that new roof shingles
have any more toxic chemical content than the ambient environment.
Unless a science research analyzes in detail the content of new roof
shingles, then I have no worry as to using it as mulch. What is known
is that my plants thrive with the shingle mulch and it is known that
plants rarely take in toxins. And it is known that if shingles are
roofs in close proximity to humans is safe as a roof then commonsense
says they would be safe for a plant.

Trouble with John is that his mind is not objective enough to be
scientific and that he sees a post by A.P. so automatically John has to
counter or argue against whatever it is I say. But this is a handicap
of 90% of the posters to the Internet sci newsgroups is that their
touchy-feely minds talks more than their objective-science mind
(however small of portion that is).

Archimedes Plutonium
www.iw.net/~a_plutonium
whole entire Universe is just one big atom
where dots of the electron-dot-cloud are galaxies