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Catharine Sauer
Lethal or Logical?
Insects
Weeds
Nematodes (round worms)
Pathogens ◦ Phytophthora cactorum (collar rot)
◦ Phytophthora fragariae (berry root rot)
◦ Verticillium dahliae (wilting disease)
◦ Colletotrichum acutatum (pathogen causing rot)
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DDT◦ Byproduct of DDE
◦ Non-toxic to humans
◦ Phased out in 1972
Methyl Bromide◦ Depletes the stratosphere
Photolyzed to elemental Bromine
More damaging than Chlorine
◦ Poisonous to humans
◦ Phased out in 2005
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1993 to 1998- Freeze at 1991 baseline levels for U.S. Consumption ~25,500 Metric Tons
1999 to 2000 - 25% reduction from baseline levels
2001 to 2002 - 50% reduction from baseline levels
2003 to 2004 70% reduction from baseline levels
2005 100% phase out with a few exceptions as allowed by the Montreal Protocol
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Propargyl bromide (PrBr)
Methyl isothiocyanate (MITC)
Combinations of 1,3-dichloropropene and Chloropicrin (CP) (InLine)
Emulsifiable combination of chloropicrin (CP-EC)
Iodomethane and CP (Midas)
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1 Day after Fumigation◦ CP-EC, InLine and Midas worked◦ MeBr+CP, MITC, PrBr similar to control
28 days◦ CP-EC ,InLine and Midas higher potential◦ MeBr+CP, PrBr and MITC showed more soil recovery
90 days◦ Midas showed overall reduction in fungal activity◦ InLine, PrBr and CP-EC reduced bacteria
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In October 2007, CH3I was approved as a trial pesticide
October 2008, CH3I approved for conditional use
CP
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Product Names % Iodomethane % Chloropicrin Characteristics
Iodomethanetechnical
99.8% ------ Least Volatile
Midas 98:2 97.8 1.99
Midas 50:50 (Midas EC Bronze)
49.9 49.75
Midas 33:67 (Midas EC Gold)
32.93 66.78
Midas 25:75 24.95 74.63 Most Volatile
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Property Iodomethane Bromomethane
Vapor Pressure mmHg
400@25oC 1420@20oC
Vapor Density @ 20oCAir=1
4.9 3.3
Solubility in Water 14g/100g 0.132g/100ml
LD50
Mg/kg ingestion for rats
76 214
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Toxic and Irritant
May be fatal if inhaled Harmful if swallowed or absorbed through
the skin A neurotoxin and a severe irritant to the
upper and lower respiratory tract, skin and eyes.
Health = 3, Fire = 1, Reactivity = 0.
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May be fatal if:
◦ Inhaled
◦ Absorbed through skin
◦ Swallowed
Affects Central Nervous System
Causes irritation to skin, eyes, respiratory tract
Health= 3, Flammability= 0, Reactivity= 1
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CH3F◦ Causes asphyxiation, narcotic effect
CH3Cl◦ CNS damage
CH3Br◦ Respiratory and kidney
◦ Neurological effects
CH3I◦ Strong Neurotoxin
◦ Very damaging to lungs
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Symmetry= F through Br are tetrahedral
CH3I is not, the bond angles are skewed causing longer bonds, increasing volatility
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54 Scientists wrote to the EPA in Sept. 2007
“As chemists and physicians familiar with the effects of this chemical, we are concerned that pregnant women and the fetus, children, the elderly, farm workers, and other people living near application sites would be at serious risk if methyl iodide is permitted for use in agriculture (80-275pounds per acre).
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“Methyl iodide is a highly reactive chemical …. Alkylating agents like methyl iodide are extraordinarily well-known cancer hazards …. because of their ability to modify the chemist’s own DNA, as well as the target molecule in the flask, leading to mutations that are potentially very harmful.
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Barrier Zones of 500ft
Cannot enter fumigated area for at least 5 days◦ Volatility of fumigants◦ 54% of CH3I is dissipated into the atmosphere upon
release◦ 21-87% for Methyl Bromide
Cannot use within a ¼ mile of a school, library or heavily trafficked area
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Only trained personnel can puncture/remove the tarp
APR vs. SCBA
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EPA respiratory Answers.com respiratory
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• Due to Iodomethanes’ volatility, it has a lifetime of 4-8 days in the atmosphere
• Iodomethane is readily photolyzed and broken down
• Bromomethane stays in the atmosphere for 2 years
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Degredation time of MeI in 1mM aqueous solution
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Vs.
• VS.
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EPA conditionally approved in March1994 for herbicide for corn
Solubility .23mg/100ml at 25 degrees C
• Less toxic than Iodomethane
• Oral LD50=1426 mg/kg to 2148 mg/kg
Concern over groundwater contamination for byproducts: acetochlor oxanilic acid and acetochlor ethanesulfonic acid
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EPA conducted the most thorough analysis yet (4 years)
As seen, MeI is highly toxic and the barrier zones are not large enough
California and Texas don’t want to use it◦ Website uses other alternatives
◦ Still conducting risk assessment on MeI
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MeBr MSDS http://www.penglaichem.com/OLDPAGE/msds-methyl%20bromide-100.htm
Methyl Bromide Fact Sheet http://npic.orst.edu/factsheets/MBtech.pdf
MeI MSDS http://www.jtbaker.com/msds/englishhtml/m5369.htm
Acetochlor Conditions http://www.regulations.gov/search/Regs/home.html#documentDetail?R=09000064802778c5
Phaseout plan http://www. Methyl Bromideepa.gov/Ozone/mbr
Fluoromethane Information http://en.wikipedia.org/wiki/Fluoromethane
Chloromethane Information http://en.wikipedia.org/wiki/Chloromethane
Bromomethane Information http://en.wikipedia.org/wiki/Bromomethane
Iodomethane Information http://en.wikipedia.org/wiki/Iodomethane
Fumigant application Picture
http://www.panna.org/mag/fall2008/change/epa-fumigant-drift
EPA Fumigant Picture http://www.epa.gov/region2/mediacenter/imagegallery/images/pesticide_application_l.jpg
Zheng, W., Papiernik, S., Guo, M., Yates, S. “Accelerated Degredation of Methyl Iodide by Agrochemicals, J. Agric. Food Chem. 2003, 51, 673-679
Klose, Susanne, Acosta-Martinez, V. Ajwa, H. “Microbial community composition and enzyme activities in a sandy loam, Soil Biology and Biochemistry 38 (2006) 1243-1254
Reiss, Richard, Griffin, J. “A Probalistic model for acute bystander exposure and risk assessment for soil fumigants”, Atmospheric Environment, 40 (2006) 3548-3560
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http://www.blogcdn.com/www.slashfood.com/media/2008/07/food-berries.jpg
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