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Following is a message I received from Ron Livingston about the pyrethrin
discussion.  I wanted to pass it along for those interested because I
believed it to be a safe substance to use.  I have only used it in my home
during one winter and am glad of that in light of the following.  Sorry if I
miss led anyone about the above subject.  He further told me the following
in how he deals with the pesky fungus knats which I found quite interesting
and if I have a repeat problem (hopefully not)  I will try this.
FROM:  Ronald Livingston <RONLIVES@prodigy.net>
Date: Wednesday, September 22, 1999 8:24 PM
Subject: Re: Pyrethrium
Are you aware of Mary's anti-fungus gnat potion ? Bt can also be mixed with
the water and kill the larval stage. I use a combination of things. One of
my favorites is an empty yellow butter tub. I put a couple of drops of dish
detergent in it and fill it up with warm water. The gnats are attracted to
the color,( like the sticky traps) once a few get in there and die they are
like decoys for the others to follow. I'd hate to say how many I have caught
this way( more than I can count ). As the new ones emerge, eventually they
take the dive.


Hi Beth,
    I contacted the people at Organic Gardening to check on pyrethrium and
rotenone. Here's the post they sent back:
> Thank you for your interest in ORGANIC GARDENING. Following is some
> information that we hope will be of help to you.
> More bad news on botanicals.  (health dangers)  Organic Gardening, Jan
> 1995 v42 n1 p20(1)  Summary Botanical pesticides may contain inert
> materials that are even more toxic than the active ingredients. The
> additive piperonyl butoxide (PBO) has been linked to liver cancer and
> reproductive problems in studies on rats.  Full Text When we discuss
> pest-control techniques in OG, we never recommend using toxic
> insecticides, even the plant-derived "botanical" ones like rotenone and
> pyrethrin which have been accepted by some growers and certifying groups
> as organic in certain circumstances. But not by us--all such botanicals
> are extremely toxic at the time they are applied, making them a danger to
> the person applying them, as well as to children, pets and other living
> things.  Now there's even more reason for us to take such a position. Like
> most pesticides, many botanicals contain "inert ingredients," some of
> which are believed to be more toxic than the active ingredients! In
> botanicals, the most troublesome "inert" is a chemical additive called PBO
> (piperonyl butoxide) which new research on animals indicates can cause
> cancer and reproductive problems.  The Aug. 1994 Technical Report of the
> National Coalition Against the Misuse of Pesticides tipped us to several
> recent studies (including one unpublished study conducted for a group of
> pesticide manufacturers that we are currently trying to obtain via the
> Freedom of Information Act) indicating that PBO "leads to liver tumors in
> both rats and mice and has adverse effects on reproductive, developmental
> and behavior patterns in mice, with increasing effects in subsequent
> generations."  One of the new pieces of research, "Chronic Toxicity
> Studies of PBO in F344 Rats: Induction of Hepatocellular Carcinoma" is the
> first published scientific report (in Fundamental and Applied Toxicology,
> Vol. 22, 1994) showing that high doses of PBO causes cancer in rats
> (toxicologists had previously suspected that PBO would cause liver cancer
> because of its strong chemical similarity to other known carcinogens).
> The EPA is now reviewing these studies; a decision on whether to restrict
> the use of PBO is expected in 1996. Until then, there are lots of
> products--both chemical and botanical--containing PBO, including many of
> the pyrethrin and rotenone garden insecticides and pyrethrin flea sprays
> and shampoos. Marion Johnson of the EPA's insecticide branch tells us that
> nearly one-third of all households use pesticides containing PBO!  (PBO
> helps an insecticide kill more insects by interfering with the bugs'
> ability to breakdown and detoxify the insecticide. [Scientists call such
> chemicals "synergists."!)  PBO was considered an extremely controversial
> ingredient in organic circles even before these studies came to light,
> however. Although it is manufactured from chemicals that are derived from
> plants, Brian Baker, technical advisor to California Certified Organic
> Farmers, tells us that PBO is not a simple extract that can be isolated
> directly from plants. Instead, manufacturers have to go through several
> chemical processes before PBO is produced. That chemical processing
> (combined with long-standing health concerns) is why many organic
> certification groups have never accepted PBO as organic.  In case this
> sounds like the reverse of something you recently read, you're right!
> Another gardening magazine recently misreported this entire issue,
> declaring PBO to be totally organic and safe, and alleging that some
> organic certification groups had prohibited PBO just because piperonyl
> butoxide "sounded like a chemical." (We know the folks who handle
> certification around the country and believe us, they base their decisions
> on a lot more than how something's name sounds to them!)  Like most of the
> botanical pesticides themselves, PBO is a "grandfathered" ingredient,
> having been granted EPA registration before the rules were as strict as
> they are today. The EPA is currently in the process of "re-registering"
> these older chemicals, which is why it's requiring and reviewing this
> additional research on PBO (and on pyrethrin and rotenone, as well). These
> materials are also currently under review by the National Organic
> Standards Board, which is scheduled to turn over its recommendations to
> the USDA very soon.  Full Text COPYRIGHT 1995 Rodale Press Inc.
> In every issue of ORGANIC GARDENING, you'll find specific guidance on how
> to "do it yourself" the organic way. To subscribe, call 1-800-666-2206 or
> visit http://www.organicgardening.com.

Hope this information is helpful.

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