September 25, 2013

DEET in Bug Repellent

In my posts about treating bug bites with charcoal and tamanu oil, I bemoaned my lack of forethought to use insect repellent.

One reader brought up the dangers of the active ingredient, DEET, present in most bug repellents. It was a very good point to address, and I realized this ingredient merits a post of it's own. When I use bug repellent, I make sure to use formulations that forgo DEET because it has been associated with serious health and environmental concerns.

The EPA has reported cases of seizures and deaths resulting from DEET-toxicity [1]. Exposure to DEET can also lead to insomnia, mood disturbances and impaired cognitive function, as reported by The Pesticide Information Project of Cooperative Extension Offices [2]. DEET has been found to inhibit the activity of an enzyme in the central nervous system in both insects and mammals known as acetylcholinesterase [3]. This enzyme plays a role in the function of the neurons which control muscles. Because of this quality, DEET is combined with insecticides, which leads to an excessive accumulation of acetylcholine at the synaptic cleft, resulting in neuromuscular paralysis and death by asphyxiation [4]. 

While DEET has not been proven to be bioaccumulate, it has a negative effect on the environment. DEET has been shown to be toxic to freswater fish and plankton [5][6][7].

DEET can cross the placenta and has been linked to birth defects such as statomotor retardation, muscular hypotonia, central hearing loss, coarctation of the aorta, strabismus and death [8], [9].

DEET is a solvent. It can dissolve plastic and synthetic fabrics [10]. It is also a known skin irritant [11]. I definitely don't want that on my skin.

DEET is good at one thing; it definitely keeps the mosquitoes and bugs away. However, there are some safer alternatives to DEET. Herbs that have been shown to deter insects include citronella, lemongrass, catnip, eucalyptus and peppermint. Once I go through tests of various ingredients and formulations, I'll make sure to report back on my results.

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[1] U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic Substances. September 1998. pp. pp 39–40.
[2] Pesticide Information Profile. EXTOXNET. October 1997.
[3] Corbel et al. (2009). "Evidence for inhibition of cholinesterases in insect and mammalian nervous systems by the insect repellent deet". BMC Biology 7:47.
[4] Purves, Dale, George J. Augustine, David Fitzpatrick, William C. Hall, Anthony-Samuel LaMantia, James O. McNamara, and Leonard E. White (2008). Neuroscience. 4th ed. Sinauer Associates. pp. 121–2.
[5] U.S. Environmental Protection Agency. 1980. Office of Pesticides and Toxic Substances. N,N-diethyl-m-toluamide (Deet) Pesticide Registration Standard. December, 1980. 83 pp.
[6] Mathai, AT; Pillai, KS; Deshmukh, PB (1998). "Acute toxicity of deet to a freshwater fish, Tilapia mossambica: Effect on tissue glutathione levels". Journal of Environmental Biology 10 (2): 87-91.
[7] J. Seo, Y. G. Lee, S. D. Kim, C. J. Cha, J. H. Ahn and H. G. Hur (2005). "Biodegradation of the Insecticide N,N-Diethyl-m-Toluamide by Fungi: Identification and Toxicity of Metabolites". Archives of Environmental Contamination and Toxicology 48(3): 323–328.
[8] Schaefer, C; Peters, P (1992) "Intrauterine diethyltoluamide exposure and fetal outcome". Reproductive Toxicity 6(2): 175-176.
[9] McGready, R et al. (2001) "Safety of the insect repellent n-n diethyl m toluamide during pregnancy". The American Society of Tropical Medicine and Hygiene 65(4), pp. 285–289.
[10] Anna Petherick (2008-03-13). "How DEET jams insects' smell sensors." Nature News.
[11] CPS&Q (Consumer Products Safety & Quality) formely known as ECB (European Chemicals Bureau). 2008. Classification and Labelling: Chemicals: Annex VI of Directive 67/548/EEC through the 31st ATP.

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1. Keeps Bugs Off

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