Generation, Transport and Transformation of Pesticide Residues
on Airborne Fine Particulate Matter Derived from Managed Soils

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Subject:  "Registered" pesticide (POISON) residues in dust from managed soils..............
 Date:     Sat, 23 Feb 2002 16:53:48 -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:    Christine Whitman whitman.christine@epa.gov

Dear Mr. Helliker,  I thought you might like to read this article:

Generation, Transport and Transformation of Pesticide Residues on Airborne Fine Particulate Matter Derived from Managed Soils (Holmén, Anastasio, Young)

The long-range atmospheric transport of pesticides (including herbicides, insecticides and fungicides) has been documented since the late 1960s (Rice and Chernyak, 1997; Risebrough et al., 1968; Sodergren, 1972). While it has generally been assumed that pesticides in the atmosphere exist predominantly in the gas phase, indirect evidence and preliminary calculations suggest that significant amounts are bound to atmospheric particulate matter (PM). These particle-bound pesticides can result from both: (1) wind- or tillage-induced surface erosion of soil particles containing adsorbed pesticides, and (2) partitioning of gas-phase pesticides to pre-existing atmospheric particles. It is important to quantify the atmospheric transport of pesticides on soil dust because off-site migration of even a small fraction of the one billion pounds of pesticides applied annually poses significant potential for adverse human and environmental health effects (Kamrin, 1997; Seiber and Woodrow, 1995). There is also evidence suggesting that the erosion of pesticide-containing soil particles is a significant pathway for the loss of applied pesticide.

Few direct measurements of the flux of airborne dust-bound pesticides from agricultural fields have been reported despite the potential significance. The proposed study will be the first to quantify the loss of pesticides bound to fine particulate matter (diameters <= 2.5 microns, i.e., PM2.5) generated during tillage-induced soil erosion. Examining how soil and pesticide physicochemical properties affect the pesticide-dust flux from the soil surface will delineate the range of conditions under which this loss mechanism is significant. Because subsequent transformation processes may mitigate the hazard posed by particle-bound pesticide leaving agricultural fields, the study will also quantify the photodegradation and gas-phase sorption/desorption reactions of pesticides on dust particles generated from a range of soils. The major goals of the proposed research are to:

1. Quantify the flux of particle-bound pesticides from agricultural fields during tillage operations under real-world field conditions. Determine the significance of this flux of particle-bound pesticides as: (i) a source for atmospheric pesticides (i.e., compared to the flux of vapor-phase pesticide), and (ii) a sink for applied pesticide.

2. Evaluate how soil and pesticide properties affect the magnitude of the dust-bound pesticide flux. Develop a framework so that fluxes of dust-bound pesticides from managed fields can be estimated for a wide range of pesticide and soil conditions.

Measure the photolysis rate and sorption/desorption behavior of dust-bound pesticide as a function of parent soil properties (moisture, organic matter and clay contents, and particle size distribution). Use this data to estimate the lifetimes and transport distances for pesticides sorbed to soil-dust particles.

http://cee.engr.ucdavis.edu/faculty/holmen/USDApest.htm

Well Mr. Helliker,  How can you "register" pesticide POISONS BEFORE these kind of studies are/were carried out?

Respectfully,  Stephen L. Tvedten

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