Lethal or Logical?
Catharine Sauer Insects Weeds Nematodes (round worms) Pathogens ◦ Phytophthora cactorum (collar rot) ◦ Phytophthora fragariae (berry root rot) ◦ Verticillium dahliae (wilting disease) ◦ Colletotrichum acutatum (pathogen causing rot)
2 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
3 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
4 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)
5 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
6 In October 2007, CH3I was approved as a trial pesticide
October 2008, CH3I approved for conditional use CP
7 Product Names % Iodomethane % Chloropicrin Characteristics Iodomethane 99.8% ------Least Volatile technical Midas 98:2 97.8 1.99 Midas 50:50 49.9 49.75 (Midas EC Bronze) Midas 33:67 32.93 66.78 (Midas EC Gold) Midas 25:75 24.95 74.63 Most Volatile
8 Property Iodomethane Bromomethane Vapor Pressure 400@25oC 1420@20oC mmHg
Vapor Density @ 4.9 3.3 20oC Air=1
Solubility in Water 14g/100g 0.132g/100ml
LD50 76 214 Mg/kg ingestion for rats
9 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.
10 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
11 CH3F ◦ Causes asphyxiation, narcotic effect
CH3Cl ◦ CNS damage
CH3Br ◦ Respiratory and kidney ◦ Neurological effects
CH3I ◦ Strong Neurotoxin ◦ Very damaging to lungs
12 Symmetry= F through Br are tetrahedral
CH3I is not, the bond angles are skewed causing longer bonds, increasing volatility
13 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).
14 “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.
15 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
16 Only trained personnel can puncture/remove the tarp APR vs. SCBA
17 EPA respiratory Answers.com respiratory
18 • 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
19 Degredation time of MeI in 1mM aqueous solution
20 Vs. • VS.
21 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
22 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
23 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
24 http://www.blogcdn.com/www.slashfood.com/media/2008/07/food-berries.jpg
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