Subject: More on why staying inside doesn't protect you from pesticice exposures-----
Date: Thu, 25 Jan 2001 10:50:15 -0500
From: Stephen Tvedten <steve@getipm.com>
Organization: Get Set Inc. (www.getipm.com)
To: Paul Helliker <phelliker@cdpr.ca.gov>
Director, State
of California, Department of Pesticide Regulation
cc: Carol Browner browner.carol@epa.gov
Dear Mr. Helliker,
I thought you might like to read an article entitled: More on why
staying inside doesn't protect you from exposures.
It can be found at: http://ehpnet1.niehs.nih.gov/docs/2001/109p47-54teschke/abstract.html
Articles - Environmental Health Perspectives Volume 109,
Number 1, January 2001
Spatial and Temporal Distribution of Airborne Bacillus
thuringiensis var. kurstaki
during an Aerial Spray Program for Gypsy Moth Eradication - Kay Teschke,1,2 Yat Chow,2 Karen Bartlett,2 Andrew Ross,2
and Chris van Netten1,2 -
1Department of Health Care and Epidemiology, University of British
Columbia, Vancouver, British Columbia, Canada 2School of Occupational and
Environmental Hygiene, University of British
Columbia, Vancouver, British Columbia, Canada
Abstract
We measured airborne exposures to the biological
insecticide Bacillus thuringiensis var. kurstaki (Btk) during an aerial spray
program to eradicate gypsy moths on the west coast of Canada. We aimed
to determine whether staying indoors during spraying reduced exposures, to
determine the rate of temporal decay of airborne concentrations, and to
determine whether drift occurred outside the spray zone. During spraying, the
average culturable airborne Btk concentration measured outdoors within the
spray zone was 739 colony-forming units (CFU)/m3 of air. Outdoor air
concentrations decreased over time, quickly in an initial phase with a half
time of 3.3 hr, and then more slowly over the following 9 days, with an
overall half-time of about 2.4 days. Inside residences during spraying,
average concentrations were initially 2-5 times lower than outdoors, but at
5-6 hr after spraying began, indoor concentrations exceeded those outdoors,
with an average of 244 CFU/m3 vs. 77 CFU/m3 outdoors, suggesting that the
initial benefits of remaining indoors during spraying may not persist as
outside air moves indoors with normal daily activities. There was drift of
culturable Btk throughout a 125- to 1,000-meter band outside the spray zone
where measurements were made, a consequence of the fine aerosol sizes that
remained airborne (count median diameters of 4.3 to 7.2 µm). Btk
concentrations outside the spray zone were related to wind speed and
direction, but not to distance from the spray zone.
http://ehpnet1.niehs.nih.gov/docs/2001/109p47-54teschke/abstract.html
Address
correspondence to K. Teschke, Department of Health Care and Epidemiology,
Mather Building, 5804 Fairview Avenue, University
of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
Telephone: (604) 822-2041. Fax: (604) 822-4994. E-mail:
teschke@interchange.ubc.ca
We
thank the study participants for welcoming study personnel into their homes
before dawn; M. Pearce and C. Bender for making logistic arrangements; and the
sampling personnel for their willingness to change plans according to
vicissitudes of aerial spray schedules. This study was funded in part by the
Capital Health Region.
Received 20 June 2000; accepted 7 September 2000.
Well Mr. Helliker,
It would be logical to extrapolate that your other
"registered" POISONS would react in the same or a similar way.
So that people staying inside during Mosquito spraying for example,
might as well go outside. They
would at least have some "fresh air" outside to help dilute the
"registered" POISON.
Respectfully, Stephen
L. Tvedten
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