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    Herbicides: How Toxic Are They?: Fred Fishel, Jason Ferrell, Greg Macdonald, and Brent Sellers

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    Mudassir Ali Qazalbash
    1) Herbicides target specific biological processes in plants like photosynthesis that are not present in mammals, so they have little impact on humans. Additionally, herbicides are often flushed from the body within 24 hours without building up to toxic levels. 2) While some herbicides like paraquat are highly toxic, most common herbicides have higher oral LD50 values (lower toxicity) than everyday products like salt, bleach, and caffeine. 3) Agent Orange, which was contaminated with the carcinogen dioxin, was an exception and caused health issues in Vietnam veterans. However, the herbicides 2,4-D and 2,4,5-T themselves were not found to

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    Herbicides: How Toxic Are They?: Fred Fishel, Jason Ferrell, Greg Macdonald, and Brent Sellers

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    Mudassir Ali Qazalbash
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    1) Herbicides target specific biological processes in plants like photosynthesis that are not present in mammals, so they have little impact on humans. Additionally, herbicides are often flushed from the body within 24 hours without building up to toxic levels. 2) While some herbicides like paraquat are highly toxic, most common herbicides have higher oral LD50 values (lower toxicity) than everyday products like salt, bleach, and caffeine. 3) Agent Orange, which was contaminated with the carcinogen dioxin, was an exception and caused health issues in Vietnam veterans. However, the herbicides 2,4-D and 2,4,5-T themselves were not found to

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    1) Herbicides target specific biological processes in plants like photosynthesis that are not present in mammals, so they have little impact on humans. Additionally, herbicides are often flushed from the body within 24 hours without building up to toxic levels. 2) While some herbicides like paraquat are highly toxic, most common herbicides have higher oral LD50 values (lower toxicity) than everyday products like salt, bleach, and caffeine. 3) Agent Orange, which was contaminated with the carcinogen dioxin, was an exception and caused health issues in Vietnam veterans. However, the herbicides 2,4-D and 2,4,5-T themselves were not found to

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    31 views2 pages

    Herbicides: How Toxic Are They?: Fred Fishel, Jason Ferrell, Greg Macdonald, and Brent Sellers

    Uploaded by

    Mudassir Ali Qazalbash
    1) Herbicides target specific biological processes in plants like photosynthesis that are not present in mammals, so they have little impact on humans. Additionally, herbicides are often flushed from the body within 24 hours without building up to toxic levels. 2) While some herbicides like paraquat are highly toxic, most common herbicides have higher oral LD50 values (lower toxicity) than everyday products like salt, bleach, and caffeine. 3) Agent Orange, which was contaminated with the carcinogen dioxin, was an exception and caused health issues in Vietnam veterans. However, the herbicides 2,4-D and 2,4,5-T themselves were not found to

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    of 2

    PI-133

    Herbicides: How Toxic Are They?1


    Fred Fishel, Jason Ferrell, Greg MacDonald, and Brent Sellers2

    An herbicide is any agent used to bring about plant death. an oral LD50 of 500 means that 500 mg of chemical was
    Although everything from salt to soap has been used for needed to obtain lethality in a 1 kg subject (rabbit). The
    this purpose, herbicides are primarily synthetic chemicals lower the LD50 value, the less chemical that is required to
    manufactured for use in the agriculture, industrial, and reach lethality. A chemical with an LD50 of 10 mg/kg is
    ornamental and turf industries. For many years, these more acutely toxic than one with an LD50 of 100 mg/kg.
    products have been seen as toxins that poison plants and
    are equally harmful to the applicator. To compound this Table 1 demonstrates that herbicides often have higher LD50
    issue, organically produced food is becoming more popular values than many commonly used or consumed products.
    because it is pesticide-free and is seen as being healthier. Why is this? Why are chemicals that are so effective on
    These factors have led to a prevalence of opinion that plant species not equally harmful to humans? The reason is
    pesticides are bad for the environment and harmful to two-fold. First, herbicides target highly specific biological
    humans. or biochemical processes within plants, such as photosyn-
    thesis and production of branch-chain amino acids. How-
    Although there have been pesticides that were toxic ever, mammals (humans included) do not photosynthesize
    and dangerous to handle, most of these products are no or produce branch-chain amino acids. Therefore, herbicides
    longer used and have been replaced by newer chemistry. that target photosynthesis or branch-chain amino acid
    Pesticides now must go through rigorous testing by the production have no place to bind in our bodies and have
    U.S. Environmental Protection Agency (EPA) before they very little impact. Secondly, since these herbicides do not
    can be sold. This has led to many herbicides that possess bind in our bodies, they are often excreted in urine within
    little or no mammalian toxicity and are less harmful than 24 hours of the dose. This flushing of the herbicide does not
    many everyday household products (Table 1). Surprisingly, allow concentrations to build up to toxic levels within the
    household chemicals that many of us store under the body. This in no way means that it is safe to intentionally
    kitchen sink pose more risk to the handler than herbicides. ingest herbicides, but the fact is that our bodies are well
    equipped to safely dispose of accidental exposure to many
    A common way to document toxicity is by oral LD50 values. common herbicides.
    LD50 is the amount of chemical required to provide a “lethal
    dose” to 50% of the test population. LD50 is measured in mg
    of chemical administered per kg of body weight. Therefore,

    1. This document is PI-133, one of a series of the Pesticide Information Office, UF/IFAS Extension. Original publication date September 2006. Revised
    February 2013. Reviewed March 2016. Visit the EDIS website at http://edis.ifas.ufl.edu.

    2. Fred Fishel, professor, Agronomy Department, and director, Pesticide Information Office; Jason Ferrell, associate professor, Agronomy Department;
    Greg MacDonald, professor, Agronomy Department; Brent Sellers, associate professor, Agronomy Department, Range Cattle Research and Education
    Center, Ona, FL; UF/IFAS Extension, Gainesville, FL 32611.

    Use herbicides safely. Read and follow directions on the manufacturer’s label.

    The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services
    only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status,
    national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county’s UF/IFAS Extension office.
    U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County
    Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.
    Table 1. Comparison of oral LD50 values for commonly used herbicides and consumer goods.
    Herbicide LD50 Common consumer chemicals LD50
    Paraquat (Gramoxone) ~100 Nicotine 9
    Triclopyr 630 Caffeine 192
    2,4-D 666 Bleach 192
    Pendimethalin (Prowl) 1050 Tylenol 338
    Atrazine 3090 Household ammonia (10%) 350
    Glyphosate (Roundup) 4900 Codeine 427
    Imazaquin (Image) >5000 Table salt 3000

    What about Agent Orange? D.C. http://www.nap.edu/catalog/11242.html#orgs. Visited


    January 2013.
    Agent Orange was an herbicide product containing equal
    parts 2,4-D and 2,4,5-T. These herbicides were used Fishel, F.M. 2005. Evaluation of pesticides for carcinogenic
    extensively in the Vietnam War to defoliate jungles in potential. PI-37. Gainesville: University of Florida Institute
    an attempt to expose troop movement. However, many of Food and Agricultural Sciences. http://edis.ifas.ufl.edu/
    veterans came forward after the war with illnesses ranging pi074. Visited January 2013.
    from a multitude of cancers to various respiratory diseases.
    It was speculated that Agent Orange was to blame for these National Pesticide Information Center (1-800-858-7378 or
    disorders. http://npic.orst.edu/). Visited January 2013.
    After numerous governmental inquiries, it was found that Nesheim, O.N., F.M. Fishel, and M. Mossler. Toxicity of
    the herbicides 2,4-D and 2,4,5-T were not responsible for pesticides. PI-13. Gainesville: University of Florida Institute
    the human health effects of Agent Orange. Rather, Agent of Food and Agricultural Sciences. http://edis.ifas.ufl.edu/
    Orange was inadvertently contaminated with dioxin, a pi008. Visited January 2013.
    potent and known carcinogen. Dioxin was an unanticipated
    by-product of the 2,4,5-T synthesis process. Although Poison Information Center Network (1-800-222-1222 or
    synthesis processes have been developed that allow http://www.fpicn.org). Visited January 2013.
    2,4,5-T to be produced without dioxin contamination,
    these procedures were not employed to fulfill this specific
    contract. Consequently, the production of 2,4,5-T has been
    totally banned by the United States and numerous other
    countries.

    Conclusion
    It must be noted that some herbicides are harmful. Herbi-
    cides such as paraquat and endothal have “Danger” signal
    words on the label and must be handled with great care.
    Therefore, it is important that all herbicides be handled
    carefully and in a manner consistent with their labeling.
    Just because some herbicides are less toxic than table salt
    does not mean that any herbicides should be handled
    carelessly. But on the other hand, using a herbicide in
    accordance with the product label will not often result in
    personal injury or cause for alarm.

    Additional Information
    Committee to Review the Health Effects in Vietnam
    Veterans of Exposure to Herbicides. 2004. Veterans and
    Agent Orange. National Academies Press. Washington,

    Herbicides: How Toxic Are They? 2

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