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Growth Regulators & Plant Hormones

Growth Regulators & Plant Hormones. Summon Chomchai, MD Toxbuster@hotmail.com. Growth regulator & plant hormone:. Growth regulator : noun Date: 1936 : any of various synthetic or naturally occurring plant substances (as an auxin or gibberellin) that regulate growth

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Growth Regulators & Plant Hormones

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  1. Growth Regulators & Plant Hormones Summon Chomchai, MD Toxbuster@hotmail.com

  2. Growth regulator & plant hormone: • Growth regulator : noun Date: 1936: any of various synthetic or naturally occurring plant substances (as an auxin or gibberellin) that regulate growth • Plant hormone: nounDate: 1935: an organic substance other than a nutrient that in minute amounts modifies a plant physiological process; especially: one produced by a plant and active elsewhere than at the site of production • Merriam-Webster Online Dictionary

  3. Growth regulators & Plant hormones in Thailand • Hydrogen cyanamide • Ethephon • Cyclocel • Thiourea • Naphylene-1-acetic acid • Gibberellic acids

  4. Hydrogen cyanamide (Dormex®) • The only hazardous growth regulator reported on MEDLINE!!! • Stimulates bud breaking after dormancy • Applied by spraying • Mode of exposure: skin and inhalation

  5. Hydrogen cyanamide • Mode of exposure: skin and inhalation • Inhibits aldehyde dehydrogenase (disulfiram-like effects) • Causes acetaldehyde syndrome when exposure coincided with alcohols

  6. Hydrogen cyanamide • 23 cases reported from Italy (MMWR October 5, 2001) • 22 cases from occupational exposure: mixing & applying • 1 unintentional ingestion • PPE status was unknown

  7. Hydrogen cyanamide • Eye and respiratory tract irritation • Skin symptoms • Systemic symptoms: tachycardia, palpitation, headache, dizziness, weakness, nausea and vomiting, dyspnea, hypotension • 12 workers were hospitalized

  8. Cyanamide: other potential health risks • Contact dermatitis • Hepatitis and liver failure • Aplastic anemia/ agranulocytosis • Disulfiram-like effects

  9. Surveillance for hydrogen cyanamide • Skin symptoms and signs • Complete blood count • Liver function test • Other symptoms

  10. Cyanamide: control of exposure • Personal protective equipment • Chemical-resistant suit • Chemical-resistant gloves • Chemical-resistant footwear • Eye and face protection • Respirator with organic vapor removing cartridge

  11. Ethephon • Enhances releasing of ethylene by plants and fruits • fruit ripening • flower induction • stem elongation • stimulate latex flow in rubber) • Applied by dipping or spraying

  12. Ethephon: health effects • Exposure: dermal or inhalation • Eye irritation; corneal erosion • Severe skin burns; may result in contractures • Lower respiratory tract irritation: bronchospasm, pneumonitis, pulmonary edema

  13. Ethephon • Decontamination & supportive care, no specific treatment • Protection: Personal protective equipment • Chemical-resistant suit • Chemical-resistant gloves • Chemical-resistant footwear • Eye and face protection • Respirator with organic vapor removing cartridge

  14. Cyclocel (Chlormequat) • Prevents premature fruit drop in oranges and mangos • Increases yields in wheat • Promotes lateral branching and flowering in geraniums

  15. Cyclocel (Chlormequat) • Dermal contact of dust and sprays, especially during application • Contact dermatitis • Supportive care/ no specific treatment • Protection: Protective clothing and gloves

  16. Thiourea • Stimulates sprouting from dormant tubers • Dermal exposure upon mixing and application • Irritant contact dermatitis / photo-contact dermatitis (rubber industry/ silver & copper cleaners) • Supportive care/ no specific treatment • Protection: Protective clothing and gloves

  17. NAPHTHALENE-1-ACETIC ACID • Stimulates root formation • Prevents premature fruit drop in apples, mangoes, watermelons, pineapples, cucumbers, cotton, soya • Controls regrowth of tree sprouts after trimming of lemon, pomegranate • Inhibits sprouting in stored potato, ornamental bulbs • Application: dipping or spraying

  18. NAPHTHALENE-1-ACETIC ACID • Expoure though inhalation during application • Nasal irritation • Supportive care, no specific treatment

  19. Gibberellic acids • No health hazard of gibberellic acids reported • Prevention: avoid contact with the chemical, wash splash from skin immediately

  20. Conclusion • Most of growth regulators and plant hormones are relatively benign. • Researches on health hazards of growth regulators and plant hormones

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