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Mosquito coils


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Facts about the most widely used mosquito repellent, the mosquito coils. Made during my TA days.

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Mosquito coils

  1. 1. Hafiz b Hassan GS26727 MOSQUITO COILS
  2. 2. WHAT ARE MOSQUITO COILS? A mosquito repelling incense  Made from pyrethrum powder - natural insecticide made from the dried flower heads of Chrysanthemum (C. cinerariifolium and C. coccineum)  Shaped into a coil – burning begins from outer end and moves into inner end producing smoke.  Typical coils 15cm from end to end, lasts 8 hours 
  3. 3. PYRETHRUM       Actually a mixture of several compounds pyrethrins , cinerins. Used to be made by grinding dried chrysanthemum flowers into a powder. Now solvent extraction is used. In Asia 200 years ago, people discovered that extracts from crushed crysanthemums kill insects. Used as ‘lice powder’ (famous usage by Napoleon and his forces) Relatively low toxicity - breaks down quickly, Generally has low environmental impact
  4. 4. HISTORY      Mosquito coils were invented by Eiichiro Ueyama. At first, he brought the pyrethrum seeds from America to be planted and milled as a flea repellant (1885) The flea repellant won Merit Prize in the 3rd National Industrial Exhibition in Tokyo (1890) After meeting an incense seller, he wanted to further simplify the application of the powder – creating ‘candles’ Original production method      mix starch powder and dried mandarin orange skin powder + pyrethrum powder, knead it thoroughly, put it into a wooden mortar, extrude it, then cut it into the form of stick incense (candle)
  5. 5.      However, the starch-pyrethrum ‘candle’ mix burns too quickly (40 minutes). Needs 2-3 candles for maximum effect Wife, Yuki, proposed elongating and thickening the candles and winding it into a spiral (1895). By 1920, a working prototype is developed (after trial and error) 1957 – mass production, machine manufactured
  6. 6. HOW THEY ARE MADE  Ingredients : Starch (potato starch, corn starch, rice or wheat starch)  Coconut flour mix  Sawdust  Dye (for colour)  Burning aids (sodium and potassium nitrate, sodium benzoate etc)  0.5% mass of insecticide   Pyrethrum/pyrethroid  Allethrin, bioallethrin
  7. 7. HOW THEY ARE MADE  Process       Dispersing from 16- 26% by weight on a dry basis potato starch in water having a temperature of from 40- 60° C.; Gelling the dispersed starch by adding sufficient water having a temperature of from 80- 95° C. to the starch-water dispersion to raise the temperature of the resulting mixture to above the gelling point of the starch; Adding from 72- 83% by weight on a dry basis of a carrier, from 0.5-3% by weight on a dry basis of an insecticide and from 0- 2% by weight on a dry basis of a burning aid to the gelled starch-water mixture; Forming thin sheets from the carrier starch-water mixture; Forming mosquito coils from the thin sheets; Drying the formed mosquito coils with the provision that the ratio of dry ingredients to water is within the range of from 1:1- 1:2.5.
  8. 8. ADVANTAGES Provides as much as 80% protection  Long term (8-10 hours) protection  No flames  Need no special equipment to be used  Portable  Chemically inert (unless ingested) 
  9. 9. DISADVANTAGES The odor and smoke – asthmatics threat  Although no flame, but sparks can be emitted – fire hazard  Releases VOC (formaldehydes), PAHs and particulate matter – hazardous to health  If used in badly ventilated area – indoor pollution and discomfort  One coil – 75 to 150 times more smoke than cigarettes. 
  10. 10. REFERENCES      Osaka Foundation for Trade & Industry (2004). Eiichiro Ueyama , Developing and promoting insecticide together with pyrethrum. Retrieved on 22 September 2010, from Sumitomi Chemical Company, Limited (1973). Fumigant Insecticidal Mixtures Of D-chrysanthemates. Retrieved on 22 September 2010, from Weili, L., Junfeng, Z., Hashim, J.H., Jalaludin, J., Hashim, Z., Goldstein, B. D. (2003). Mosquito Coil Emissions and Health Implications. Environmental Health Perspectives 111 (12): 1454–1460 DAINIHON JOCHUGIKU Co.,Ltd. History of Kincho Corp. Retrieved on 27 September 2010 from Histria Aromatica, 2005. The History of Pyrethrum. Retrieved in 27 September 2010 from