4.2 Safety of plant-based repellents

Because many conventional pesticide products fall into disfavor with the public, botanical-based pesticides should become an increasingly popular choice as repellents. There is a perception that natural products are safer for skin application and for the environment, just because they are natural and used for a long time compared to synthetic non-biodegradable products [14]. In contrast to DEET, some natural repellents are safer than others, and plant-based repellents do not have this strictly tested safety evidence, and many botanical repellents have compounds that need to be used with caution [39]. PMD has no or very little toxicity to the environment and poses no risks to humans and animals. PMD has been developed and registered for use against public health pests and is available as a spray and lotion. Not much is known about the toxicity of eucalyptus oils; however, they have been categorized as GRAS by the US EPA. Further, the oral and acute LD50 of eucalyptus oil and cineole to rat is 4440 mg/kg body weight (BW) and 2480 mg/kg BW, respectively, making it much less toxic than pyrethrins (LD50 values 350– 500 mg/kg BW; US EPA, 1993) and even technical grade pyrethrum (LD50 value 1500 mg/kg BW) [40]. PMD is an important component of commercial repellents in the US and registered by US EPA and Canadian Pest Management Regulatory Agency in 2000 and 2002, respectively [13]. In contrary, lemon eucalyptus EO does not have US EPA registration for use as an insect repellent. PMD is the only plantbased repellent that has been advocated for use in disease-endemic areas by the Centers for Disease Control (CDC), due to its proven clinical efficacy to prevent malaria, and is considered to pose no risk to human health [39]. In 2005, the US Centers for Disease Control and Prevention made use of its influence by endorsing products containing "oil of lemon eucalyptus" (PMD), along with picaridin and DEET as the most effective repellents of mosquito vectors carrying the West Nile virus [67]. PMD provides excellent safety profile with minimal toxicity. In studies using laboratory animals, PMD demonstrated no adverse effects apart from eye irritation. It is safe for both children and adults as the toxicity of PMD is very low. However, the label indicates it should not be used on children under the age of 3 [7].

The safety of neem is extensively reviewed; azadirachtin is nontoxic to mammals and did not show chronic toxicity. Even at high concentrations, neem products were neither mutagenic nor carcinogenic, and they did not produce any skin irritations or organic alterations in mice and rats. On the other hand, reversible reproduction disturbances could occur due to the daily feeding of aqueous leaf extract for 6 and 9 weeks led to infertility of rats at 66.7 and 100%, respectively. Using unprocessed and aqueous neem-based products should be encouraged if applied with care. The pure compound azadirachtin, the unprocessed materials, the aqueous extracts, and the seed oil are safe to use even as insecticides to protect stored food for human consumption, whereas nonaqueous extracts turn out to be relatively toxic [8]. From the ecological and environmental standpoint, azadirachtin is safe and nontoxic to fish, natural enemies, pollinators, birds, and other wildlife. Azadirachtin is classified by the US EPA as class IV (practically nontoxic) [7, 8, 17] as azadirachtin breaks down within 50–100 h in water and is degraded by sunlight as the half-life of azadirachtin is only 1 day, leaving no residues. Safety and advantages of EOs are widely discussed [7, 8, 17, 39]. There is a popular belief that EOs are benign and harmless to the user. Honestly, increasing the concentration of plant EOs as repellents could increase efficacy, but high concentrations may also cause contact dermatitis. Some of the purified terpenoid ingredients of EOs are moderately toxic to mammals. Because of their volatility, EOs have limited persistence under field conditions. With few exceptions, the oils themselves or products based on them are mostly nontoxic to mammals, birds, and fish. Many of the commercial products that include EOs (EOs) are on the "generally recognized as safe" [64] list fully approved by the US FDA and EPA for food and beverage consumption. Moreover, EOs are usually devoid of long-term genotoxic risks, and some of them show a very clear antimutagenic capacity which could be linked to an anticarcinogenic activity. The prooxidant activity of EOs or some of their constituents, like that of some polyphenols, is capable of reducing local tumor volume or tumor cell proliferation by apoptotic and/or necrotic effects. Due to the capacity of EOs to interfere with mitochondrial functions, they may add prooxidant effects and thus become genuine antitumor agents. The cytotoxic capacity of the essential oils, based on a prooxidant activity, can make them outstanding antiseptic and antimicrobial agents for personal uses, that is, for purifying air, personal hygiene, or even internal use via oral consumption and for insecticidal use for the preservation of crops or food stocks. Some EOs acquired through diet are actually beneficial to human health [68, 69]. Eugenol is an eye and skin irritant and has been shown to be mutagenic and tumorigenic. Citronellol and 2-phenylethanol are skin irritants, and 2-phenylethanol is an eye irritant, mutagen, and tumorigenic; they also affect the reproductive and central nervous systems [30]. Hence, it is advised that EOs with toxic profile should be used for treating clothing rather than direct application to individual's skin [13]. Although EOs are exempt from registration through the US EPA, they can be irritating to the skin, and their repellent effect is variable, dependent on formulation and concentration. The previously mentioned safety and advantages designate that EOs could find their way from the traditional into the modern medical, insecticidal, and repellent domain.

against mosquitoes and other biting insects. Unfortunately, the widespread use and effectiveness of commercial formulations containing DEET and other synthetic substances could lead to resistance [70, 71]. Some health and environmental concerns lead to the search for natural alternative repellents. The use of repellent plants has been used since antiquity [1], and it is the only effective protection available for the poor people against vectors and their associated diseases [71]. Ethnobotanical experience is passed on orally from one generation to another, but it needs to be preserved in a written form and utilized as a rich source of botanicals in repellent bioassays. Then again, the growing demand for natural repellents points up the further necessity to evaluate new plant-based products critically for personal protection against mosquitoes and mosquito-borne diseases [7, 8, 17, 18]. Regarding environmental and health concerns, plant-based repellents are better than synthetic molecules. Even though many promising plant repellents are available, their use is still limited; therefore, advance understanding of the chemical ecology of pests and the mode of repellency would be helpful for identifying competitor semiochemicals that could be incorporated into attractant or repellent formulations. There are numerous commercially available formulations enhancing the longevity of repellent, by controlling the rate of delivery and the rate of evaporation. Such formulations are very useful to people living in the endemic areas in the form of sprays, creams, lotions, aerosols, oils, evaporators, patch, canister, protective clothing, insecticide-treated clothing, and insecticide-treated bed nets [7, 8, 17]. The potential uses and benefits of microencapsulation and nanotechnology are enormous including enhancement involving nanocapsules for pest management and

Commercial Mosquito Repellents and Their Safety Concerns

DOI: http://dx.doi.org/10.5772/intechopen.87436

nanosensors for pest detection [7, 8]. Nanoparticles are effectively used to control

Polymer-based formulations allow entrapping active ingredients and provide release control. Encapsulation into polymeric micro/nanocapsules, cyclodextrins, polymeric micelles, or hydrogels constitutes an approach to modify physicochemical properties of encapsulated molecules. Such techniques, applied in topical formulations, fabric modification for personal protection, or food packaging, have been proven to be more effective in increasing repellency time and also in reducing drug dermal absorption, improving safety profiles of these products. In this work, the main synthetic and natural insect repellents are described as well as their polymeric carrier systems and their potential applications [79]. Encapsulated EO nanoemulsion is prepared to create stable droplets to increase the retention of the oil and slow down release. The release rate correlates well to the protection time so that a decrease in release rate can prolong mosquito protection time. Microencapsulation is another way to slowly release the active ingredients of repellents. In laboratory conditions, the microencapsulated formulations of the EOs showed no significant difference with regard to the duration of repellent effect compared to the microencapsulated DEET used at the highest concentration (20%). It exhibited >98% repellent effect for the duration of 4 h, whereas, in the field conditions, these formulations demonstrated the comparable repellent effect (100% for a duration of 3 h) to Citriodiol®-based repellent (Mosiguard®). In both test conditions, the microencapsulated formulations of the EOs presented longer duration of 100% repellent effect (between 1 and 2 h) than non-encapsulated formulations [80]. Microencapsulation reduces membrane permeation of CO while maintaining a constant supply of the citronella oil [81]. Moreover, using gelatin Arabic gum micro-

capsules also prolonged the effect of natural repellents. In addition, the

157

functionalization of titanium dioxide nanoparticles on the surface of polymeric microcapsules was investigated as a mean to control the release of encapsulated citronella through solar radiation. The results showed that functionalizing the microcapsules with nanoparticles on their surface and then exposing them to

larvae [72–76] and to repel adults of mosquitoes [77, 78].

#### 5. Conclusions and challenges for future research

Several diseases transmitted by mosquitoes cause high losses of human and animal lives every year. DEET is considered as a "gold standard" to which other candidate repellents are compared; therefore, DEET is the most ever-present active ingredient used in commercially available repellents, with noteworthy protection

#### Commercial Mosquito Repellents and Their Safety Concerns DOI: http://dx.doi.org/10.5772/intechopen.87436

The safety of neem is extensively reviewed; azadirachtin is nontoxic to mammals and did not show chronic toxicity. Even at high concentrations, neem products were neither mutagenic nor carcinogenic, and they did not produce any skin irritations or organic alterations in mice and rats. On the other hand, reversible reproduction disturbances could occur due to the daily feeding of aqueous leaf extract for

6 and 9 weeks led to infertility of rats at 66.7 and 100%, respectively. Using unprocessed and aqueous neem-based products should be encouraged if applied with care. The pure compound azadirachtin, the unprocessed materials, the aqueous extracts, and the seed oil are safe to use even as insecticides to protect stored food for human consumption, whereas nonaqueous extracts turn out to be relatively toxic [8]. From the ecological and environmental standpoint, azadirachtin is safe and nontoxic to fish, natural enemies, pollinators, birds, and other wildlife. Azadirachtin is classified by the US EPA as class IV (practically nontoxic) [7, 8, 17] as azadirachtin breaks down within 50–100 h in water and is degraded by sunlight as the half-life of azadirachtin is only 1 day, leaving no residues. Safety and advantages of EOs are widely discussed [7, 8, 17, 39]. There is a popular belief that EOs are benign and harmless to the user. Honestly, increasing the concentration of plant EOs as repellents could increase efficacy, but high concentrations may also cause contact dermatitis. Some of the purified terpenoid ingredients of EOs are moderately toxic to mammals. Because of their volatility, EOs have limited persistence under field conditions. With few exceptions, the oils themselves or products based on them are mostly nontoxic to mammals, birds, and fish. Many of the commercial products that include EOs (EOs) are on the "generally recognized as safe" [64] list fully approved by the US FDA and EPA for food and beverage consumption. Moreover, EOs are usually devoid of long-term genotoxic risks, and some of them

show a very clear antimutagenic capacity which could be linked to an

modern medical, insecticidal, and repellent domain.

156

Malaria

5. Conclusions and challenges for future research

Several diseases transmitted by mosquitoes cause high losses of human and animal lives every year. DEET is considered as a "gold standard" to which other candidate repellents are compared; therefore, DEET is the most ever-present active ingredient used in commercially available repellents, with noteworthy protection

anticarcinogenic activity. The prooxidant activity of EOs or some of their constituents, like that of some polyphenols, is capable of reducing local tumor volume or tumor cell proliferation by apoptotic and/or necrotic effects. Due to the capacity of EOs to interfere with mitochondrial functions, they may add prooxidant effects and thus become genuine antitumor agents. The cytotoxic capacity of the essential oils, based on a prooxidant activity, can make them outstanding antiseptic and antimicrobial agents for personal uses, that is, for purifying air, personal hygiene, or even internal use via oral consumption and for insecticidal use for the preservation of crops or food stocks. Some EOs acquired through diet are actually beneficial to human health [68, 69]. Eugenol is an eye and skin irritant and has been shown to be mutagenic and tumorigenic. Citronellol and 2-phenylethanol are skin irritants, and 2-phenylethanol is an eye irritant, mutagen, and tumorigenic; they also affect the reproductive and central nervous systems [30]. Hence, it is advised that EOs with toxic profile should be used for treating clothing rather than direct application to individual's skin [13]. Although EOs are exempt from registration through the US EPA, they can be irritating to the skin, and their repellent effect is variable, dependent on formulation and concentration. The previously mentioned safety and advantages designate that EOs could find their way from the traditional into the

against mosquitoes and other biting insects. Unfortunately, the widespread use and effectiveness of commercial formulations containing DEET and other synthetic substances could lead to resistance [70, 71]. Some health and environmental concerns lead to the search for natural alternative repellents. The use of repellent plants has been used since antiquity [1], and it is the only effective protection available for the poor people against vectors and their associated diseases [71]. Ethnobotanical experience is passed on orally from one generation to another, but it needs to be preserved in a written form and utilized as a rich source of botanicals in repellent bioassays. Then again, the growing demand for natural repellents points up the further necessity to evaluate new plant-based products critically for personal protection against mosquitoes and mosquito-borne diseases [7, 8, 17, 18]. Regarding environmental and health concerns, plant-based repellents are better than synthetic molecules. Even though many promising plant repellents are available, their use is still limited; therefore, advance understanding of the chemical ecology of pests and the mode of repellency would be helpful for identifying competitor semiochemicals that could be incorporated into attractant or repellent formulations. There are numerous commercially available formulations enhancing the longevity of repellent, by controlling the rate of delivery and the rate of evaporation. Such formulations are very useful to people living in the endemic areas in the form of sprays, creams, lotions, aerosols, oils, evaporators, patch, canister, protective clothing, insecticide-treated clothing, and insecticide-treated bed nets [7, 8, 17]. The potential uses and benefits of microencapsulation and nanotechnology are enormous including enhancement involving nanocapsules for pest management and nanosensors for pest detection [7, 8]. Nanoparticles are effectively used to control larvae [72–76] and to repel adults of mosquitoes [77, 78].

Polymer-based formulations allow entrapping active ingredients and provide release control. Encapsulation into polymeric micro/nanocapsules, cyclodextrins, polymeric micelles, or hydrogels constitutes an approach to modify physicochemical properties of encapsulated molecules. Such techniques, applied in topical formulations, fabric modification for personal protection, or food packaging, have been proven to be more effective in increasing repellency time and also in reducing drug dermal absorption, improving safety profiles of these products. In this work, the main synthetic and natural insect repellents are described as well as their polymeric carrier systems and their potential applications [79]. Encapsulated EO nanoemulsion is prepared to create stable droplets to increase the retention of the oil and slow down release. The release rate correlates well to the protection time so that a decrease in release rate can prolong mosquito protection time. Microencapsulation is another way to slowly release the active ingredients of repellents. In laboratory conditions, the microencapsulated formulations of the EOs showed no significant difference with regard to the duration of repellent effect compared to the microencapsulated DEET used at the highest concentration (20%). It exhibited >98% repellent effect for the duration of 4 h, whereas, in the field conditions, these formulations demonstrated the comparable repellent effect (100% for a duration of 3 h) to Citriodiol®-based repellent (Mosiguard®). In both test conditions, the microencapsulated formulations of the EOs presented longer duration of 100% repellent effect (between 1 and 2 h) than non-encapsulated formulations [80]. Microencapsulation reduces membrane permeation of CO while maintaining a constant supply of the citronella oil [81]. Moreover, using gelatin Arabic gum microcapsules also prolonged the effect of natural repellents. In addition, the functionalization of titanium dioxide nanoparticles on the surface of polymeric microcapsules was investigated as a mean to control the release of encapsulated citronella through solar radiation. The results showed that functionalizing the microcapsules with nanoparticles on their surface and then exposing them to


Repellent composition

159

Citronella

3% citronella

candles

Citronella

5% citronella

incense

GonE!®

Aloe vera, camphor, menthol, oils of eucalyptus, lavender,

1 ml/650 cm2

> rosemary, sage, and soybean

> > Green Ban for

Citronella 10%, peppermint oil 2%

People®

Herbal

Citronella 12%, peppermint oil 2.5%, cedar oil 2%, lemongrass

Armor®

Kor Yor 15

DEET 24%, DEET 24%,

dimethylphthalate

 24%

dimethylphthalate

 24%

0.1 ml/30 cm2

0.1 ml/30 cm2

DEET lotion®

MeiMei®

Citronella and geranium oils

Citronella and geranium oils

Mistine

IR 3535 12%, rosemary, lavender, and eucalyptus

0.1 ml/30 cm2

0.1 ml/30 cm2

1 g/600 cm2

1 g/lower leg

Walk-in exposure

room test

Arm-in-cage Arm-in-cage Arm-in-cage

An. stephensi

Ae. aegypti

Ae. aegypti

1 h 1 h 4–5 h 7–8 h

[91]

[92]

[95]

censor®

Mospel®

 Clove oil 10% Makaen oil 10%

IR 3535 12%, rosemary, lavender, and eucalyptus

cream

oil 1%, geranium oil 0.055

Dose

Study variety

Field trial in

Aedes spp.

Canada

Field trial in

Aedes spp.

Ae. albopictus

0.0 h

[87]

Commercial Mosquito Repellents and Their Safety Concerns

2.8 h 14 min

[90]

Cx. nigripalus

> Arm-in-cage

Arm-in-cage Arm-in-cage Arm-in-cage

Indoor test Field trial in South

Aedes (7.8%)

Armigeres (5.9%)

Anopheles (42.2%)

Culex (44.1%)

Korea

Ae. aegypti

Ae. aegypti

Ae. aegypti

3 h 3 h 97

30 min

[93]

97

50 min

85

70 min

44

90 min

27

90

30 min

[94]

57

90 min

56

150 min

34

210 min

120 min

[91]

[92]

Ae. aegypti

18.9 min

[90]

Ae. aegypti

Canada

 Mosquito spp.

Mean

Protection

 Reference

CPT

% Time interval

42.3 24.2

[89]

DOI: http://dx.doi.org/10.5772/intechopen.87436

[89]

### Malaria


#### Commercial Mosquito Repellents and Their Safety Concerns DOI: http://dx.doi.org/10.5772/intechopen.87436

Repellent composition

158

Bio Skincare®

BioUD® spray 7.75% 2-undecanone

 Natural oil of jojoba, rapeseed, coconut, and vit. E

1.2 g/arm

1 ml/600 cm2

Arm-in-cage Arm-in-cage

Ae. aegypti

An. arabiensis

Dose

Study variety

 Mosquito spp.

Mean

Protection

 Reference

Malaria

CPT

% Time interval

100

3–4 h

[85]

52

96.1

1 h

[86]

86.7

2 h

81.7

3 h

79.5

4 h

70.1

5 h

68.2

94.5

1 h

98.3

2 h

93.1

3 h

79.4

4 h

87.4

5 h

76.3

98.4

3 h

94.2

4 h

92.2

5 h

79

95.5

4 h

95.6

6 h

6 h

7.75% 2-undecanone

> Bite Blocker®

Glycerin, lecithin, vanillin, oils of coconut, geranium, and

1 ml/650 cm2

> soybean (2%)

lotion

Bite Blocker

3% soybean oil

Xtreme®

6% geranium oil

8% castor oil

> Buzz Off Insect

Natural plant extract

1 g/forearm

Repellent®

Baygon®

 Oils of canola, eucalyptus, peppermint, rosemary, and sweet

1 ml/650 cm2

birch

1 ml/600 cm2

Field trial in North

Ae. Psorophora ferox (54.7%)

atlanticus/tormentor

 (23.3%)

> Carolina (USA)

Field trial in

Ae. vexans (32%) Ae. euedes

(29.3%) Ae. stimulans (15.3%)

Canada

Arm-in-cage Field trial in

Ae. vexans (32%) Ae. euedes (29.3%) Ae. stimulans (15.3%)

> Arm-in-cage

> Ae. aegypti

0 min

[88]

0 min 160 min

50 min

0.2 h

[87]

4.7 h

Ae. vigilax Cx. Annulirostris

Cx.

> Arm-in-cage

Ae. albopictus Cx. nigripalus

quinquefasciatus

Canada

Ae. albopictus

5.5 h

[87]

8.3 h

93.9

4 h

[86]

53.7

6 h

Cx. nigripalus

6 h

Ae. albopictus

6 h

6 h


Repellent composition

161

Repel Care®

 Turmeric oil 5%

2 ml/750 cm2

Field trial in

Ae. aegypti (1.2%)

Others (<1%) Cx. vishnui (77.1%)

Cx.

Cx. gelidus (3.4%)

Cx.

> Duration of the

Ae. albopictus (99.9%)

100

Commercial Mosquito Repellents and Their Safety Concerns

DOI: http://dx.doi.org/10.5772/intechopen.87436

96.9

92.4

91.8

Ar. subalbatus (0.01%)

test: 8 h

> Turmeric oil 5%

0.1 ml/30 cm2

0.1 ml/30 cm2

0.1 ml/30 cm2

Arm-in-cage Arm-in-cage Arm-in-cage

Ae. aegypti

4 h

4 h

4 h

[92]

Ae. aegypti

3 h

[92]

Ae. aegypti

1 h

[92]

E. citriodora 4.5%

Sketolene®

DEET, E. citriodora oil 15%

lotion

Soffell®

DEET 13%, citronella oil

> (citronella oil)

Soffell®

DEET 13%, geranium

(floral

fragrance)

Soffell®

DEET 13%, orange

(fresh

fragrance)

Soffell® lotion DEET, E. citriodora oil 15%

0.1 ml/30 cm2

Field trial in

Ae. gardnerii

100 (120 min) [91]

> Ae. lineatopennis

An. barbirostris

Cx.

Cx. gelidus

Tritaeniorhynchus

Thailand

(duration of the

test: 120 min)

tritaeniorhynchus

 (1.6%)

quinquefasciatus (13.8%)

Thailand

(duration of the

test: 9 h)

E. citriodora 4.5%

Dose

Study variety

 Mosquito spp.

Mean

Protection

 Reference

CPT

% Time interval

100

#### Malaria


#### Commercial Mosquito Repellents and Their Safety Concerns DOI: http://dx.doi.org/10.5772/intechopen.87436

Repellent composition

160

MosquitoSafe®

Neem Aura®

 Aloe vera, extract of barberry, chamomile, goldenseal, myrrh,

neem, and thyme; oil of anise, cedarwood, citronella, coconut,

lavender, lemongrass, neem, orange, rhodium wood

Odomos®

Advanced Odomos (12%

N,N-diethylbenzamide)

8 mg/cm2

10 mg/cm2

10 mg/cm2

12 mg/cm2

10 mg/cm2

10 mg/cm2

10 mg/cm2

> Raid Dual

transfluthrin-based

 spatial repellent products

> Action and

Raid Shield

Field trial in India

An. culicifacies

An. stephensi An. annularis An. subpictus

Cx. Ae. aegypti

> Laboratory (wind

> Aedes aegypti

> > tunnel) and

semi-field

(outdoor

enclosure) in

Florida

quinquefasciatus

9 h 6.2 h 92.5

95

[97]

and

74

88

and

66

 98.8

Duration of the

test: 11 h

Advanced odomos

Ae. aegypti

Arm-in-cage

Cx. nigripalus

3.8 h

>4 h 100

4 h >4 h 100

11 h

 100

 96.5

[96]

(Duration of the

test: 4 h)

cream

 Geraniol 25%, mineral oil 74%, aloe vera 1%

1 ml/650 cm2

1 ml/650 cm2

Arm-in-cage Arm-in-cage

Ae. albopictus

Cx. nigripalus

Ae. albopictus

2.8 h

0.2 h

4.2 h

[87]

[87]

Dose

Study variety

 Mosquito spp.

Mean

Protection

 Reference

Malaria

CPT

% Time interval


Table 1. Commercial

mosquito-repellent

 products. ultraviolet radiation effectively increased the output of citronella into the air for repelling the mosquitoes without human intervention, as the sunlight works as a

It is recommended to use US EPA-registered insect repellents including one of the active ingredients: DEET, Picaridin, IR3535, Oil of lemon eucalyptus (OLE), Para-menthane-diol (PMD), and 2-undecanone. Synthetic MRs are applied for years but induced some safety and environmental concerns; as a result, the

advancement in the development of repellents from the botanical origin is encouraged. But some obstacles are hindering botanical repellents which as the source availability, standardization, commercialization, and analyses in order to certify the efficacy and safety [7]. Commercially available repellents are provided in Table 1

For saving time and efforts, a high-throughput chemical informatics screen via a structure-activity approach, molecular-based chemical prospecting [83], as well as computer-aided molecular modeling [84] would accelerate the exploration of new environmentally safe and cost-effective novel repellents which activated the same chemosensory pathways as DEET at a fairly shorter time and lower costs [13]. The selection of various repellents could be tailored along with the profile of safety

annoyance and the incidence of illness. The use of these technologies to enhance the performance of natural repellents may revolutionize the repellent market and make EOs a more viable option for use in long-lasting repellents. Green technologies and cash cropping of repellent plants afford a vital source of income for small-scale farmers and producers in developing countries and raise the national economy. Moreover, in some developing countries where tourism is a chief source of national income, the use of repellents would increase the pleasure and comfort of tourists. Finally, much faster work needs to be done to discover new and safe repellents for

.

' and military destinations by reducing

release activator [82].

concerns and biting vectors at the travelers

Commercial Mosquito Repellents and Their Safety Concerns

DOI: http://dx.doi.org/10.5772/intechopen.87436

personal protection from mosquitoes.

163

#### Malaria

#### Commercial Mosquito Repellents and Their Safety Concerns DOI: http://dx.doi.org/10.5772/intechopen.87436

ultraviolet radiation effectively increased the output of citronella into the air for repelling the mosquitoes without human intervention, as the sunlight works as a release activator [82].

It is recommended to use US EPA-registered insect repellents including one of the active ingredients: DEET, Picaridin, IR3535, Oil of lemon eucalyptus (OLE), Para-menthane-diol (PMD), and 2-undecanone. Synthetic MRs are applied for years but induced some safety and environmental concerns; as a result, the advancement in the development of repellents from the botanical origin is encouraged. But some obstacles are hindering botanical repellents which as the source availability, standardization, commercialization, and analyses in order to certify the efficacy and safety [7]. Commercially available repellents are provided in Table 1. For saving time and efforts, a high-throughput chemical informatics screen via a structure-activity approach, molecular-based chemical prospecting [83], as well as computer-aided molecular modeling [84] would accelerate the exploration of new environmentally safe and cost-effective novel repellents which activated the same chemosensory pathways as DEET at a fairly shorter time and lower costs [13]. The selection of various repellents could be tailored along with the profile of safety concerns and biting vectors at the travelers' and military destinations by reducing annoyance and the incidence of illness. The use of these technologies to enhance the performance of natural repellents may revolutionize the repellent market and make EOs a more viable option for use in long-lasting repellents. Green technologies and cash cropping of repellent plants afford a vital source of income for small-scale farmers and producers in developing countries and raise the national economy. Moreover, in some developing countries where tourism is a chief source of national income, the use of repellents would increase the pleasure and comfort of tourists. Finally, much faster work needs to be done to discover new and safe repellents for personal protection from mosquitoes.

Repellent composition

162

Sumione®

Metofluthrin-treated

 emanators

900-cm2 paper fan emanators

Field trials in PA,

Aedes canadensis

USA

impregnated with 160 mg

metofluthrin

4000-cm2 paper strip emanators

Laboratory-reared

89–

91

Aedes aegypti

impregnated with 200 mg

metofluthrin

Metofluthrin-impregnated

strip emanator

Metofluthrin-impregnated

strip emanator

1 ml/650 cm2

0.1 ml/30 cm2

0.1 ml/30 cm2

Arm-in-cage Arm-in-cage Field study in USA Ae. albopictus and Ae.

taeniorhynchus

Anopheles Culex erraticus, and

columbiae

Anopheles Culex erraticus, and

columbiae

quadrimaculatus,

Psorophora

quadrimaculatus,

Psorophora

Ae. aegypti

Ae. aegypti

0 h 0.5 h

3 h

 70

[99]

and

79

Up

[100]

to

84

Up

[100]

to

84

[100]

[100]

[91]

[92]

SunSwat®

 Oils of bay, cedarwood, citronella, goldenseal, juniper, lavender, lemon peel, patchouli, pennyroyal, tansy, tea tree,

and vetiver

Tipskin®

 Bergamot oil, citronella oil, camphor oil, and vanillin

Bergamot oil, citronella oil,

camphor oil, and vanillin

> OFF! Clip-On®

Mosquito

Linalool

Cognito®

No-Pest Strip® Dichlorvos

Thermacell®

Table 1. Commercial

mosquito-repellent

 products.

 d-cis/trans allethrin

 Metofluthrin

 paper

In Washington

Aedes vexans

State

Arm-in-cage

Ae. albopictus

0.2 h

[87]

4.2 h

Cx. nigripalus

 paper

In Florida

Ochlerotatus spp.

91–

95

95–

97

Dose

Study variety

 Mosquito spp.

Mean

Protection

 Reference

Malaria

CPT

% Time interval

85–

[98]

100
