lethal or logical?

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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