L.Bui_Log

__**Article Summary:**__ //Brown, M., & Hebert, A. A. (1997). Insect repellents: An overview. Journal of the American Academy of Dermatology, 36(2 Pt 1), 243-249.// DOI
 * Insect repellents: An overview**

+ DEET was first marketed in 1956 and it has the most efficient insect repellent agent since then. However, permethrin is better for tick bites than DEET. DEET does give serious side effects. The article will mention about the current, popular repellent agents and their active ingredients. Also the guidelines for safe use of insect repellents from the Environmental Protection Agency will be mentioned.

+ The statement of the fact of feeding mosquitoes when walking in the woods in the summer when there are a lot of flies.

+ Factors attract mosquitoes and diseases which can be caused by mosquito bites.

+ The idea of how repellent agents repel insects.

+ The factors can shorten the lasting period of time of repellent agents. Ways for the best results are mentioned.

+ There are many repellent compounds which are tested by the U.S. Bureau of Entomology and Plant Quarantine can repel insects.

+ Different form of repellent agents and the factors affect effectiveness such as the ingredients of repellent agents, body, insects…

+ Criteria which a good repellent agent should have are long duration of effectiveness, non-annoying to skin, refreshing smell, not damaging clothes, pleasing feel on skin after removal, inactivity to popularly used plastics, stability and availability of chemicals for wide uses.

+ __Background:__ Types of repellents. Four major repellents used before World War II and years of discovery.

+ __Oil of citronella:__ oil of citronella comes from the leaves of a tropical grass in Asia and tropical America. Before 1940s, it was the most common and best repellent agent. Beside citronella, other essential oils were used too. Joss sticks made from pyrethrum became popular. Natrapel and Green Ban are present repellents containing citronella.

+ __Dialkyl phthalates:__ • Dialkyl phthalates were one of early discovered repellents. dimethyl phthalate was used as a solvent for repellent tests. This paragraph also showed how the effectiveness of n-butyl sulfone changed when it interacted with dimethyl phthalate. • It was said that dimethyl and dibutyl phthalates were nontoxic from 1930 to 1940 but after that they were considered toxic but they were still used. They were common ingredients found in most repellents at that time. They were also a good choice for ixodid ticks. • The different amount of dimethyl phthalate versus the amount of DEET needs to use to give efficient result.

+ __Indalone (butyl 3,4-dihydro-2,2-dimethyl-4-oxo-2H-pyran-6-carboxylate)__: Indalone is a good choice for tick repellents. Insects are scared away only if they interact with the area where repellent has applied.

+ __Rutgers 612 (containing 2-ethyl-1,3-hexanediol)__: • Rutgers 612 is not in use anymore even though other repellents contain its active ingredient. 2-ethyl-1,3- hexanediol can be used to repel mosquitoes effectively but it is not a good choice for ticks. • Using 2-ethyl-1,3-hexanediol may cause moderate erythema, irritation and a danger of birth defect if used by pregnant women.

+ __Table I__: Active ingredients and formulations of different kinds of repellent agents.

+ __DEET__: • Soldiers served in the wars in the past had to deal with diseases relating to many types of arthropod. Clinical studies on insect repellents started in 1942. DEET was discovered during these studies. • Because of the ability of preventing many insects, DEET has been known as the best insect repellent since it was first on the market. • DEET is safe for some fabric materials but not all. DEET is also flammable.

+ __Adverse effects__: • Report on cases in which people had slight reactions after 8 to 48 hours using or in contact with DEET. This happened on children more on adults. • Report on more serious cases in which two out of five persons drinking too much concentrated DEET products died, the other three survived. Adults using products which contain less than 50% DEET seldom had side effects. Children who are in contact with products containing 20% DEET had some side effects or died if used it repeatedly. People who used products containing 50% to 75% DEET had redness on their skin, blisters or some other side effects. • DEET can cause cardiovascular toxicity with clinical signs of hypotension and bradycardia. • After many studies and investigations, researchers concluded that using DEET can cause slight advert effects. • Recommended proper usages and concentrations for different situations for good results.

+ __Table II__: Guidelines from Environmental Protection Agency to use insect repellents safely.

+ __Efficacy__: • The studies on how the efficiency of products containing DEET concentration from 50% to 100% is. • A repellent agent called Editar developed and tested by U.S. Army give a good result and efficiency but it is not available on the market. • The combination of army camouflage face paint and an extended-duration repellent agent can repel Aedes aegypti and Anopheles stephensi mosquitoes up to 6 hours.

+ __Permethrin__: • Permethrin acts as an insecticide and a repellent. It works for a broad range of pests and insects. • Permethrin sprays are sold in stores and used to spray on tent or clothing to prevent ticks. It lasts for couple washing. If permethrin gets on skin, wash with water and soap is needed only. • For ticks prevention, it is recommended to use permethrin and apply it on clothing. • A trial of using 1% permethrin formula to prevent mosquitoes. • The result of using 0.5% permethrin aerosol after couple applications every 15 or 30 seconds. • Comparison of the efficiency of DEET and permethrin in ticks prevention was carried out. Permethrin is a more efficient tick repellent than DEET. • Using repellent soap gives the best protection after application, but the efficiency goes down within 4 hours later.

+ __Conclusion__: DEET is a good repellent agent for most of insect bites but permethrin is the best for stick bites. Follow the Environmental Protection Agency guidelines to decrease side effect or toxicity that insect repellents might cause.