Parasitol Res (2014) 113:185–188 DOI 10.1007/s00436-013-3641-7
ORIGINAL PAPER
Evaluation of biological and chemical insect repellents and their potential adverse effects Margit Semmler & Fathy Abdel-Ghaffar & Jürgen Schmidt & Heinz Mehlhorn
Received: 16 September 2013 / Accepted: 4 October 2013 / Published online: 19 October 2013 # Springer-Verlag Berlin Heidelberg 2013
Abstract Plant extracts, particularly plant oils, had been used and were still in use as repellents against mosquitoes. Some of them (e.g., lavender, geraniol, and citriodiol) have been notified by the European Commission as active substances to be used in repellents, which are categorized as biocides in product type 19. In the literature, it is known that these substances must be added to repellent products in high concentrations (e.g., 20 % and more) in order to reach repellent efficacy. Therefore, the question arose whether they also have repellent effects if they were added as fragrances at low concentrations of 0.25 or 1 % to registered active substances in order to obtain a better scent of this product. In the present study, the repellent effects of 0.25 and 1 % additions of 15 plant extracts (citronellol, cinerol, citral, menthol, linalyl acetate, Eucalyptus citriodora, Eucalyptus globulus, Cymbopogon nardus, lilac, sandalwood, Vitex agnus castus, rosewood, lavender, geraniol, and paramenthan diol) when exposed on skin to hungry Aedes aegypti mosquitoes. These experiments showed that there was no repellent effect in any of these compounds even when the test was done already 10 min after distributing any of the compounds onto the hands of volunteers. These experiments have proven that these 15 compounds do not produce repellent effects as long as they are used in low concentrations
M. Semmler : F. Abdel-Ghaffar Department of Zoology, Faculty of Science, Cairo University, Giza, Egypt J. Schmidt LifeScience Center, Alpha-Biocare GmbH, Merowinger Platz 1a, Düsseldorf, Germany H. Mehlhorn (*) Unit of Parasitology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany e-mail: [email protected]
of 0.25 or 1 % as fragrances to ameliorate the odor of a notified repellent that is brought onto the skin.
Introduction Mosquitoes and ticks are vectors of important agents of diseases of humans such as viruses, bacteria, and various kinds of parasites (Mehlhorn 2008; Cox et al. 2005; Aspöck 2010). Therefore, protection against the bites of these nasty bloodsuckers is highly needed in endemic regions. However, even if no agents of diseases were transmitted, protection is still highly desirable, since the injected saliva of these arthropods often leads to severe itching allergic reactions and pain at the bite sites. Therefore, since ancient times, humans of all high cultures developed repellents to protect their members. Of course these repellents were at first prepared from extracts of various plants (Bingen 1170). Some of them are used even today. However, their protection rates are low, in general, and the health of sensitive persons is endangered by allergic effects reaching up to anaphylactic shock (Uter et al. 2010, 2013; Lalko and Api 2005; Frosch et al. 2002). These low or reduced repellent effects of plant oils or of plant extracts were the reason that intense research started early in the last century leading to the finding of several chemical compounds such as dimethyl phthalate (phthalic acid dimethyl ester), indalone, ethyl hexane diol (Rutger 612), Merck 3535 (IR 3535), N ,N -diethyl phenylacetamide (DEET), and KBR (= Bayrepel, Icaridin, picaridin, Saltidin) among others. Especially the latter two chemical compounds are used today worldwide in a very broad range of formulations and dosages (Nentwig 2003). The European Union authorities placed by law some substances—natural or chemical ones—as repellents into the product type 19 of the so-called biocides. From 2014 onwards, only a few ones will be allowed to continue in the market. This
186
further distribution, however, requires the establishment of a full dossier on proofs (e.g., efficacy, health safety, and environmental safety). Therefore, compounds (essential oils or plant extracts) like citronellol, citral, cineol, menthol, linalyl acetate, and extracts of Eucalyptus globulus or Cymbopogon nardus , which were proven to have considerable repellent effects (Amer and Mehlhorn 2006a, b), are prohibited to be used as active ingredients (as repellents) in biocides of product type 19. Among the few remaining notified repellents now, some are synthetic compounds (DEET, paramenthan diol, Icaridin) and others are of plant origin (e.g., lavender, geraniol). Fragrances like oils of lilac, rosewood, sandalwood, and extract of Vitex agnus castus had not been listed as notified ingredients, although some of them may bring about protection as repellents if they were applied in higher concentrations. On the other hand, Eucalyptus-extracted paramenthan diol, geraniol, and lavender are listed as notified agents acting as repellents. However, their repellent effects become only dicernable if they were used at concentrations higher than 10 % (Amer and Mehlhorn 2006a). Since these compounds are also contained at low concentrations in fragrances used for body care products, it is of interest whether they exert a repelling effect when being sprayed at concentrations of 0.25 or 1 % onto skin that is exposed to hungry mosquitoes. In order to clarify this question, plant-derived compounds notified and not anymore allowed were brought onto hands of volunteers at concentrations of 0.25 or 1 % before being exposed to hungry Aedes aegypti mosquitoes, and their effects were compared to those of two synthetical repellents (DEET, Saltidin = Icaridin).
Materials and methods Mosquitoes Two thousand female and male mosquitoes of the species A. aegypti were kept in a transparent plastic cage provided with a typical access and had been offered a sucrose solution. Before starting the experiments, the mosquitoes starved for 24 h and had only access to a sponge soaked with tap water. Products The compounds listed in Table 1 were diluted at the concentrations of 0.25 or 1 % by dilution with 4 % PEG-40hydrogenated castor oil and 12.5 % ethanol in water. Procedures The hands of five volunteers were covered by plastic gloves. By help of a pair of scissors, a circular area with a diameter of 4.5 cm was cut out from the glove at the back of the hand.
Parasitol Res (2014) 113:185–188
Then 100 μl of the 0.25 and 1 % solution of each test solutions, respectively, were applied by help of a pipette onto the naked skin of the unprotected area of the hand of several volunteers. The scheduled tests were started 10 and 30 min after one of the products had been placed onto the hand and was distributed there by rubbing. Repellent failure was defined to occur as soon as three mosquitoes had sucked blood at the impregnated skin within 3 min after the first exposure.
Results The tests were performed with each product at concentrations of 0.25 and 1 %. These products belonged to the three groups which now exist according to the legislation of the European Community (EU) (Table 1): 1. notified active agents containing plant-derived compounds and synthetic ones 2. formerly used active agents, which are not allowed from now on 3. fragrances not listed in EU biocides It was seen that neither concentrations of 0.25 % nor those of 1 % of the different plant-derived compounds—independent whether they belonged to the older, not notified compounds or to the now notified compounds—had a significant repellent effect, since it took only 4–20 s at maximum until three mosquitoes had started their blood meal on the skin treated by use of one of the different compounds (Table 1). The same was seen when the oils of lilac, sandalwood, rosewood, or lavender were used. The synthetic products Icaridin and DEET at a concentration of 10 % showed full protection within three test minutes starting 10 or 30 min after the spraying of the product onto the skin at the upper side of the hands of each test person (Table 1).
Discussion Bites of mosquitoes have to be avoided since, on the one side, they may introduce pain, itching, and allergic reactions, and on the other side, agents of severe diseases may be transmitted to humans in many countries around the world (Mehlhorn 2008; Aspöck 2010). Therefore, most of the different human high cultures developed repellents, which in former times were exclusively based on plant extracts (Bingen 1170; Büchel 1970) being added to chemical ones since the twentieth century. While plant-derived products have a relatively limited time wherein they remain stable (Amer and Mehlhorn 2006b, c, d), synthetic compounds do not share this problem (Nentwig 2003). Comparing plant extracts and synthetic compounds (DEET, Icaridin = Saltidin), it was found in all cases that high concentrations of at least 20 % will achieve relevant
Parasitol Res (2014) 113:185–188 Table 1 Repellent effects of repellent substances and of selected fragrances
187
Products
Dilutions %
Group 1: former, now not notified substances Citronellol 0.25 Citronellol 1.00 Cineol 1.00 Citral 1.00 Methol 1.00 Linalyl acetate 1.00 Eucalyptus citriodora 0.25 Eucalyptus citriodora 1.00 Eucalyptus globulus 1.00 Cymbopogon nardus 0.25 Cymbopogon nardus 1.00 Group 2: fragrances not listed in EU documents Lilac 1.00 Sandalwood 1.00 Vitex extract 1.00 Rosewood 1.00 Group 3A: notified plant-derived active substances Lavender 1.00 Geraniol 0.25 Geraniol 1.00 Para-menthan diol/Eucalyptus 1.00 Group 3B: notified synthetic active substances Icaridin DEET Group 4: controls Tap water Dry, untreated skin
repellency independently whether the compounds are plantderived or synthetic chemicals. However, only a few plantderived compounds showed sufficient and long-lasting repellency (Amer and Mehlhorn 2006a). Furthermore, these efficacies depended on the mosquito species. When comparing laboratory strains of A. aegypti, Culex quinquefasciatus, and Anopheles stephensi, it turned out that A. aegypti was the most aggressive species and was considerably less long repelled by plant extracts as well as by DEET or Icaridin/ Saltidin than A. stephensi or C. quinquefasciatus (Amer and Mehlhorn 2006a). When testing low concentrations of plant-derived products—officially notified by European law as active agents or not or just considered as fragrances in cosmetic products—it turned out that none of the tested products (Table 1) showed any repellent efficacy when used in concentrations of only 0.25 % or even 1 %. Thus, even officially notified compounds such as lavender, geraniol, or paramenthan diol had no efficacy in these low concentrations and therefore have to be considered solely as fragrances in repellent products based on
Biting activity 10 min after spraying
Repellency
3 mosquitoes bite within 8 s 3 mosquitoes bite within 4 s 3 mosquitoes bite within 5 s 4 mosquitoes bite within 15 s
No No No No
4 mosquitoes bite within 9 s 5 mosquitoes bite within 20 s 4 mosquitoes bite within 10 s 4 mosquitoes bite within 12 s 3 mosquitoes bite within 20 s 3 mosquitoes bite within 7 s 3 mosquitoes bite within 12 s
No No No No No No No
4 mosquitoes bite within 9 s 3 mosquitoes bite within 20 s 3 mosquitoes bite within 8 s 3 mosquitoes bite within 7 s
No No No No
3 mosquitoes bite within 7 3 mosquitoes bite within 8 3 mosquitoes bite within 8 3 mosquitoes bite within 7
No No No No
s s s s
10.00 10.00
No mosquitoes bite within 3 min No mosquitoes bite within 3 min
Yes Yes
100.00 0.00
10 mosquitoes bite within 5 s 12 mosquitoes bite within 7 s
No No
other active compounds. However, if plant extracts like geraniol or lavender were then added to a product, particularly an active compound in a range of 20 % or higher, sensitizations, particularly allergic reactions, may occur in sensitive persons (Frosch et al. 2002; Lalko and Api 2005; Trattner et al. 2009; Faulde 2001; Uter et al. 2010, 2013; Shutty et al. 2013; Hagvall et al. 2013). However, low dosages below 1 %, e.g., in the case of geraniol, apparently do not produce strong allergic reactions (Hagvall et al. 2013); otherwise, they would not have done their tests starting with 4 % and higher concentrations. Since also notified synthetic products such as DEET may introduce unwanted effects such as contact urticaria, as was shown by Shutty et al. 2013 in a comparative test with picaridin (which remained negative), each user of repellents must test his personal potential for allergic reactions. But in any case, EU-notified repellents (lavender, geraniol, and paramenthan diol) do not function at low concentrations of 0.25 and 1 % as effective repellents and thus have to be considered as fragrances adding better scent to products containing definitively active compounds in repellency.
188
References Amer A, Mehlhorn H (2006a) Repellency effect of forty-one essential oils against Aedes, Anopheles and Culex mosquitoes. Parasitol Res 99: 478–490 Amer A, Mehlhorn H (2006b) Persistency of larvadicidal effects of plant oils under different storage conditions. Parasitol Res 99:473–477 Amer A, Mehlhorn H (2006c) The sensilla of Aedes and Anopheles mosquitoes and their importance in repellency. Parasitol Res 99: 491–499 Amer A, Mehlhorn H (2006d) Larvicidal effects of various essential oils against Aedes, Anopheles and Culex larvae (Diptera, Culicidae). Parasitol Res 99:466–472 Aspöck H (ed) (2010) Arthropods as vectors of agents of diseases. Denisia 30, Landesmuseum Austria, Vienna Bingen H (1170) Physica. New edition (1974). Müller Wiss Buchgesellnschaft, Salzburg (in German) Büchel KH (1970) Insekten-Repellents. In: Wegler H (ed) Chemie der Pflanzenschutz- und Schädlingsbekämpfungsmittel. Springer, New York, pp 487–496 Cox FEG, Wakelin D, Despommier DD (eds) (2005) Parasitology, vol 5, Topley Wilson's microbiology and microbial infections. Hodder Arnold, London Faulde M (2001) Repellentien. In: Korting HC, Sterry W (eds) Therapeutische Verfahren in der Dermatologie. Dermatika und Kosmetika. Blackwell, Berlin, pp 727–741
Parasitol Res (2014) 113:185–188 Frosch PJ, Johansen JD, Menne T et al (2002) Further important sensitizers in patients sensitive to fragrances. Contact Dermatitis 47:279– 287 Hagvall L, Karlberg AT, Christensson JB (2013) Finding the optimal patch test material and test concentration to detect contact allergy to geraniol. Contact Dermatitis 68:224–231 Lalko J, Api AM (2005) Investigation of the dermal sensitization potential of various essential oils in the local lymph node assay. Food Chem Toxicol 44:739–746 Mehlhorn H (ed) (2008) Encyclopedia of parasitology, 3rd edn. Springer, Heidelberg Nentwig G (2003) Use of repellents as prophylactic agents. Parasitol Res 90:S40–S48 Shutty B, Swender D, Chernin L et al (2013) Insect repellents and contact urticaria: different response to DEET and picaridin. Cutis 91:280– 282 Trattner A, David M, Lazarov A (2009) Occupational contact dermatitis due to essential oils. Contact Dermatitis 58:282–284 Uter W, Schmidt E, Geier J et al (2010) Contact allergy to essential oils: current patch test results (2000–2008) from information network of Departments of Dermatology (IVDK). Contact Allergy 63:277–283 Uter W, Johansen JD, Börje A et al (2013) Categorization of fragrance contact allergens for prioritization of preventive measures: clinical and experimental data and consideration of structure–activity and relationships. Contact Dermatitis 69(4):196–230
ORIGINAL PAPER
Evaluation of biological and chemical insect repellents and their potential adverse effects Margit Semmler & Fathy Abdel-Ghaffar & Jürgen Schmidt & Heinz Mehlhorn
Received: 16 September 2013 / Accepted: 4 October 2013 / Published online: 19 October 2013 # Springer-Verlag Berlin Heidelberg 2013
Abstract Plant extracts, particularly plant oils, had been used and were still in use as repellents against mosquitoes. Some of them (e.g., lavender, geraniol, and citriodiol) have been notified by the European Commission as active substances to be used in repellents, which are categorized as biocides in product type 19. In the literature, it is known that these substances must be added to repellent products in high concentrations (e.g., 20 % and more) in order to reach repellent efficacy. Therefore, the question arose whether they also have repellent effects if they were added as fragrances at low concentrations of 0.25 or 1 % to registered active substances in order to obtain a better scent of this product. In the present study, the repellent effects of 0.25 and 1 % additions of 15 plant extracts (citronellol, cinerol, citral, menthol, linalyl acetate, Eucalyptus citriodora, Eucalyptus globulus, Cymbopogon nardus, lilac, sandalwood, Vitex agnus castus, rosewood, lavender, geraniol, and paramenthan diol) when exposed on skin to hungry Aedes aegypti mosquitoes. These experiments showed that there was no repellent effect in any of these compounds even when the test was done already 10 min after distributing any of the compounds onto the hands of volunteers. These experiments have proven that these 15 compounds do not produce repellent effects as long as they are used in low concentrations
M. Semmler : F. Abdel-Ghaffar Department of Zoology, Faculty of Science, Cairo University, Giza, Egypt J. Schmidt LifeScience Center, Alpha-Biocare GmbH, Merowinger Platz 1a, Düsseldorf, Germany H. Mehlhorn (*) Unit of Parasitology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany e-mail: [email protected]
of 0.25 or 1 % as fragrances to ameliorate the odor of a notified repellent that is brought onto the skin.
Introduction Mosquitoes and ticks are vectors of important agents of diseases of humans such as viruses, bacteria, and various kinds of parasites (Mehlhorn 2008; Cox et al. 2005; Aspöck 2010). Therefore, protection against the bites of these nasty bloodsuckers is highly needed in endemic regions. However, even if no agents of diseases were transmitted, protection is still highly desirable, since the injected saliva of these arthropods often leads to severe itching allergic reactions and pain at the bite sites. Therefore, since ancient times, humans of all high cultures developed repellents to protect their members. Of course these repellents were at first prepared from extracts of various plants (Bingen 1170). Some of them are used even today. However, their protection rates are low, in general, and the health of sensitive persons is endangered by allergic effects reaching up to anaphylactic shock (Uter et al. 2010, 2013; Lalko and Api 2005; Frosch et al. 2002). These low or reduced repellent effects of plant oils or of plant extracts were the reason that intense research started early in the last century leading to the finding of several chemical compounds such as dimethyl phthalate (phthalic acid dimethyl ester), indalone, ethyl hexane diol (Rutger 612), Merck 3535 (IR 3535), N ,N -diethyl phenylacetamide (DEET), and KBR (= Bayrepel, Icaridin, picaridin, Saltidin) among others. Especially the latter two chemical compounds are used today worldwide in a very broad range of formulations and dosages (Nentwig 2003). The European Union authorities placed by law some substances—natural or chemical ones—as repellents into the product type 19 of the so-called biocides. From 2014 onwards, only a few ones will be allowed to continue in the market. This
186
further distribution, however, requires the establishment of a full dossier on proofs (e.g., efficacy, health safety, and environmental safety). Therefore, compounds (essential oils or plant extracts) like citronellol, citral, cineol, menthol, linalyl acetate, and extracts of Eucalyptus globulus or Cymbopogon nardus , which were proven to have considerable repellent effects (Amer and Mehlhorn 2006a, b), are prohibited to be used as active ingredients (as repellents) in biocides of product type 19. Among the few remaining notified repellents now, some are synthetic compounds (DEET, paramenthan diol, Icaridin) and others are of plant origin (e.g., lavender, geraniol). Fragrances like oils of lilac, rosewood, sandalwood, and extract of Vitex agnus castus had not been listed as notified ingredients, although some of them may bring about protection as repellents if they were applied in higher concentrations. On the other hand, Eucalyptus-extracted paramenthan diol, geraniol, and lavender are listed as notified agents acting as repellents. However, their repellent effects become only dicernable if they were used at concentrations higher than 10 % (Amer and Mehlhorn 2006a). Since these compounds are also contained at low concentrations in fragrances used for body care products, it is of interest whether they exert a repelling effect when being sprayed at concentrations of 0.25 or 1 % onto skin that is exposed to hungry mosquitoes. In order to clarify this question, plant-derived compounds notified and not anymore allowed were brought onto hands of volunteers at concentrations of 0.25 or 1 % before being exposed to hungry Aedes aegypti mosquitoes, and their effects were compared to those of two synthetical repellents (DEET, Saltidin = Icaridin).
Materials and methods Mosquitoes Two thousand female and male mosquitoes of the species A. aegypti were kept in a transparent plastic cage provided with a typical access and had been offered a sucrose solution. Before starting the experiments, the mosquitoes starved for 24 h and had only access to a sponge soaked with tap water. Products The compounds listed in Table 1 were diluted at the concentrations of 0.25 or 1 % by dilution with 4 % PEG-40hydrogenated castor oil and 12.5 % ethanol in water. Procedures The hands of five volunteers were covered by plastic gloves. By help of a pair of scissors, a circular area with a diameter of 4.5 cm was cut out from the glove at the back of the hand.
Parasitol Res (2014) 113:185–188
Then 100 μl of the 0.25 and 1 % solution of each test solutions, respectively, were applied by help of a pipette onto the naked skin of the unprotected area of the hand of several volunteers. The scheduled tests were started 10 and 30 min after one of the products had been placed onto the hand and was distributed there by rubbing. Repellent failure was defined to occur as soon as three mosquitoes had sucked blood at the impregnated skin within 3 min after the first exposure.
Results The tests were performed with each product at concentrations of 0.25 and 1 %. These products belonged to the three groups which now exist according to the legislation of the European Community (EU) (Table 1): 1. notified active agents containing plant-derived compounds and synthetic ones 2. formerly used active agents, which are not allowed from now on 3. fragrances not listed in EU biocides It was seen that neither concentrations of 0.25 % nor those of 1 % of the different plant-derived compounds—independent whether they belonged to the older, not notified compounds or to the now notified compounds—had a significant repellent effect, since it took only 4–20 s at maximum until three mosquitoes had started their blood meal on the skin treated by use of one of the different compounds (Table 1). The same was seen when the oils of lilac, sandalwood, rosewood, or lavender were used. The synthetic products Icaridin and DEET at a concentration of 10 % showed full protection within three test minutes starting 10 or 30 min after the spraying of the product onto the skin at the upper side of the hands of each test person (Table 1).
Discussion Bites of mosquitoes have to be avoided since, on the one side, they may introduce pain, itching, and allergic reactions, and on the other side, agents of severe diseases may be transmitted to humans in many countries around the world (Mehlhorn 2008; Aspöck 2010). Therefore, most of the different human high cultures developed repellents, which in former times were exclusively based on plant extracts (Bingen 1170; Büchel 1970) being added to chemical ones since the twentieth century. While plant-derived products have a relatively limited time wherein they remain stable (Amer and Mehlhorn 2006b, c, d), synthetic compounds do not share this problem (Nentwig 2003). Comparing plant extracts and synthetic compounds (DEET, Icaridin = Saltidin), it was found in all cases that high concentrations of at least 20 % will achieve relevant
Parasitol Res (2014) 113:185–188 Table 1 Repellent effects of repellent substances and of selected fragrances
187
Products
Dilutions %
Group 1: former, now not notified substances Citronellol 0.25 Citronellol 1.00 Cineol 1.00 Citral 1.00 Methol 1.00 Linalyl acetate 1.00 Eucalyptus citriodora 0.25 Eucalyptus citriodora 1.00 Eucalyptus globulus 1.00 Cymbopogon nardus 0.25 Cymbopogon nardus 1.00 Group 2: fragrances not listed in EU documents Lilac 1.00 Sandalwood 1.00 Vitex extract 1.00 Rosewood 1.00 Group 3A: notified plant-derived active substances Lavender 1.00 Geraniol 0.25 Geraniol 1.00 Para-menthan diol/Eucalyptus 1.00 Group 3B: notified synthetic active substances Icaridin DEET Group 4: controls Tap water Dry, untreated skin
repellency independently whether the compounds are plantderived or synthetic chemicals. However, only a few plantderived compounds showed sufficient and long-lasting repellency (Amer and Mehlhorn 2006a). Furthermore, these efficacies depended on the mosquito species. When comparing laboratory strains of A. aegypti, Culex quinquefasciatus, and Anopheles stephensi, it turned out that A. aegypti was the most aggressive species and was considerably less long repelled by plant extracts as well as by DEET or Icaridin/ Saltidin than A. stephensi or C. quinquefasciatus (Amer and Mehlhorn 2006a). When testing low concentrations of plant-derived products—officially notified by European law as active agents or not or just considered as fragrances in cosmetic products—it turned out that none of the tested products (Table 1) showed any repellent efficacy when used in concentrations of only 0.25 % or even 1 %. Thus, even officially notified compounds such as lavender, geraniol, or paramenthan diol had no efficacy in these low concentrations and therefore have to be considered solely as fragrances in repellent products based on
Biting activity 10 min after spraying
Repellency
3 mosquitoes bite within 8 s 3 mosquitoes bite within 4 s 3 mosquitoes bite within 5 s 4 mosquitoes bite within 15 s
No No No No
4 mosquitoes bite within 9 s 5 mosquitoes bite within 20 s 4 mosquitoes bite within 10 s 4 mosquitoes bite within 12 s 3 mosquitoes bite within 20 s 3 mosquitoes bite within 7 s 3 mosquitoes bite within 12 s
No No No No No No No
4 mosquitoes bite within 9 s 3 mosquitoes bite within 20 s 3 mosquitoes bite within 8 s 3 mosquitoes bite within 7 s
No No No No
3 mosquitoes bite within 7 3 mosquitoes bite within 8 3 mosquitoes bite within 8 3 mosquitoes bite within 7
No No No No
s s s s
10.00 10.00
No mosquitoes bite within 3 min No mosquitoes bite within 3 min
Yes Yes
100.00 0.00
10 mosquitoes bite within 5 s 12 mosquitoes bite within 7 s
No No
other active compounds. However, if plant extracts like geraniol or lavender were then added to a product, particularly an active compound in a range of 20 % or higher, sensitizations, particularly allergic reactions, may occur in sensitive persons (Frosch et al. 2002; Lalko and Api 2005; Trattner et al. 2009; Faulde 2001; Uter et al. 2010, 2013; Shutty et al. 2013; Hagvall et al. 2013). However, low dosages below 1 %, e.g., in the case of geraniol, apparently do not produce strong allergic reactions (Hagvall et al. 2013); otherwise, they would not have done their tests starting with 4 % and higher concentrations. Since also notified synthetic products such as DEET may introduce unwanted effects such as contact urticaria, as was shown by Shutty et al. 2013 in a comparative test with picaridin (which remained negative), each user of repellents must test his personal potential for allergic reactions. But in any case, EU-notified repellents (lavender, geraniol, and paramenthan diol) do not function at low concentrations of 0.25 and 1 % as effective repellents and thus have to be considered as fragrances adding better scent to products containing definitively active compounds in repellency.
188
References Amer A, Mehlhorn H (2006a) Repellency effect of forty-one essential oils against Aedes, Anopheles and Culex mosquitoes. Parasitol Res 99: 478–490 Amer A, Mehlhorn H (2006b) Persistency of larvadicidal effects of plant oils under different storage conditions. Parasitol Res 99:473–477 Amer A, Mehlhorn H (2006c) The sensilla of Aedes and Anopheles mosquitoes and their importance in repellency. Parasitol Res 99: 491–499 Amer A, Mehlhorn H (2006d) Larvicidal effects of various essential oils against Aedes, Anopheles and Culex larvae (Diptera, Culicidae). Parasitol Res 99:466–472 Aspöck H (ed) (2010) Arthropods as vectors of agents of diseases. Denisia 30, Landesmuseum Austria, Vienna Bingen H (1170) Physica. New edition (1974). Müller Wiss Buchgesellnschaft, Salzburg (in German) Büchel KH (1970) Insekten-Repellents. In: Wegler H (ed) Chemie der Pflanzenschutz- und Schädlingsbekämpfungsmittel. Springer, New York, pp 487–496 Cox FEG, Wakelin D, Despommier DD (eds) (2005) Parasitology, vol 5, Topley Wilson's microbiology and microbial infections. Hodder Arnold, London Faulde M (2001) Repellentien. In: Korting HC, Sterry W (eds) Therapeutische Verfahren in der Dermatologie. Dermatika und Kosmetika. Blackwell, Berlin, pp 727–741
Parasitol Res (2014) 113:185–188 Frosch PJ, Johansen JD, Menne T et al (2002) Further important sensitizers in patients sensitive to fragrances. Contact Dermatitis 47:279– 287 Hagvall L, Karlberg AT, Christensson JB (2013) Finding the optimal patch test material and test concentration to detect contact allergy to geraniol. Contact Dermatitis 68:224–231 Lalko J, Api AM (2005) Investigation of the dermal sensitization potential of various essential oils in the local lymph node assay. Food Chem Toxicol 44:739–746 Mehlhorn H (ed) (2008) Encyclopedia of parasitology, 3rd edn. Springer, Heidelberg Nentwig G (2003) Use of repellents as prophylactic agents. Parasitol Res 90:S40–S48 Shutty B, Swender D, Chernin L et al (2013) Insect repellents and contact urticaria: different response to DEET and picaridin. Cutis 91:280– 282 Trattner A, David M, Lazarov A (2009) Occupational contact dermatitis due to essential oils. Contact Dermatitis 58:282–284 Uter W, Schmidt E, Geier J et al (2010) Contact allergy to essential oils: current patch test results (2000–2008) from information network of Departments of Dermatology (IVDK). Contact Allergy 63:277–283 Uter W, Johansen JD, Börje A et al (2013) Categorization of fragrance contact allergens for prioritization of preventive measures: clinical and experimental data and consideration of structure–activity and relationships. Contact Dermatitis 69(4):196–230
