Test Results on 25 Mosquito Repellents by Consumer Council Show One Sample That Seemed to Attract Rather Than Repel Mosquitoes

The Consumer Council evaluated 25 mosquito repellents on the market and found that nearly 90 percent of them containing DEET or picaridin still provided 80 percent or more protection four hours after application. Samples claiming to be "natural" or "herbal" were shown to be less effective repellents against Aedes aegypti (yellow fever) mosquito. Bill Cox/The Epoch Times

To keep mosquitos away in summer, we often resort to mosquito repellents while enjoying nature and outdoor activities. However, it is still necessary to be aware of the ingredients of the chosen repellant. The Hong Kong Consumer Council evaluated lately 25 mosquito repellents on the market and found that one of them, “ Cherub Rubs All-Natural Organic Moisturizing Mosquito Repellent Lotion” from Australia, priced at HK$208 (US$27) per bottle, became more “attractive to mosquitoes ” after 1 hour of application, making it the worst performer as a repellant among the 25.

9 Samples Still Show 96 Percent Efficacy 4 Hours After Application

Among the 25 mosquito repellents tested, five were labeled containing DEET, four with picaridin, two with ethyl butylcetylaminopropionate (IR3535), three with p-menthane-3.8-diol (PMD), one with cedar oil, and two with wild tomato extract, while eight others claim to be “natural” or “herbal.” The samples ranged from HK$18.9 (US$2.4) to HK$259 (US$33) per bottle. Among them, the 22 packaged as sprays, droplets, and liquids were all quantified in milliliters, with an average selling price per milliliter ranging from HK$0.2 (US$0.03) to HK$2.8 (US$0.4), a 13-fold difference.

The test was conducted in Australia with mosquito species Culex quinquefasciatus (commonly known as “southern house mosquito”), and Aedes aegypti (commonly known as “yellow fever mosquito”) using the “arm-in-cage” laboratory method. The skins of the human forearms were first applied with mosquito repellent and data was then taken at four different time points after application, namely 30 minutes, 1 hour, 2 hours, and 4 hours. The numbers of mosquitoes that landed on the treated forearms were compared with the numbers on forearms without repellent as control.

It was found that nearly 90 percent of the samples containing DEET or picaridin could still provide 80 percent or more protection 4 hours after application; nine samples were still able to provide 96 percent or more protection against southern house mosquitoes, with seven of them reaching 100 percent.

The Consumer Council reminds readers the use of high-concentration DEET products or excessive exposure to this ingredient may cause rashes, blisters, and irritation of the skin and mucous membranes. There are also different recommendations for the use of DEET products on children in different regions. The Hong Kong Center for Health Protection (CHP) recommends that children should, whenever possible, use low-concentration DEET repellents (up to a limit of 10 percent), and infants under 6 months old should avoid using any unless they are travelling to places where mosquito-borne diseases are prevalent (such as dengue fever and Zika virus). As for the potential eye irritation caused by picaridin, the Western Australian Department of Health does not recommend its use by children under the age of 12 months, whereas Health Canada recommends that it should not be used by infants under 6 months of age.

3M Performed the Best, Cherub Rubs Was Rated Worst

For Aedes aegypti (yellow fever mosquito), the efficacy of all DEET samples was maintained at 80 percent or above after 4 hours, except that the efficacy of the “Speetox” sample, which was labelled with a lower concentration of DEET, dropped to 35 percent after 4 hours. Among them, the “3M” sample produced the best protection of all. It was able to achieve the “no mosquitoes landed” on the skins of the testers’ forearms at any time point.

Eight samples claimed to contain “natural” or “herbal” ingredients, such as citronella oil, lemongrass oil, soybean oil, and lemon eucalyptus oil. All of these samples were less effective in repelling the Aedes aegypti (yellow fever) mosquito. In particular, Cherub Rubs from Australia had the average number of landings by both types of mosquitoes on the forearms higher than that on the untreated forearms at most time points. The Consumer Council pointed out that this indicates certain ingredients contained in the sample may be attractive to mosquitoes, luring them to land if left on the skin.

However, the manufacturer concerned responded that the product was primarily an outdoor moisturizer rather than a mosquito repellent and that it could provide a certain mosquito repellent effect for a relatively short period of time when staying outdoors, and considered that the product should not be required to pass the relevant tests. The Consumer Council urges members of the public to first consult their doctors and pharmacists, and choose suitable products based on usage and one’s physical condition. If you need to travel to areas where mosquito-borne diseases are prevalent, you should choose products with strong protective acumen, such as DEET, picaridin, IR3535, and PMD.