Last updated: 07/12/01

MOSI-GUARD NATURAL ROLL-ON, SPRAY, STICK, AEROSOL AND CREAM

Extract

PREPARED BY:

MOSI-GUARD INTERNATIONAL LIMITED

MOORFIELD ROAD

YEADON

LEEDS

LS19 7BN

TEL: 0113 238 7502

FAX: 0113 238 7503

E-MAIL: mosi-guard@dial.pipex.com

WEB SITE: www.mosi-guard.com

First prepared: AUGUST 1995

Issued by:

Biting insects are a concern for people in many parts of the world. In the warmer areas they are a constant problem, and many are also major vectors of diseases such as malaria and yellow fever. In the cooler countries like Northern Europe and America at certain times of the year the indigenous mosquitoes and other biting insects are a considerable nuisance, as their bites often cause severe irritation and are prone to secondary infections. Delayed hypersensitivity is not uncommon following repeated insect bites and a number of cases resulting in the death of patients following immunological complications have been recorded.

For many years chemical repellents have been found to be effective in repelling biting insects thus providing some degree of personal protection. Diethyltoluamide (DEET) has until now been considered the most effective substance available. Unfortunately, despite its effective repellent action, DEET is a strong solvent which readily dissolves plastics (watch faces, camera cases etc.) and marks varnished surfaces. A number of other chemical repellents are occasionally used such as dimethyl phthalate and hexanediol. Although these synthetic compounds were undoubtedly the most effective in terms of active repellency they may also exhibit undesirable toxic effects.

In the many millions of repeated human applications of DEET over the years there have been a range of side effects noted, mostly limited to skin problems, including blisters, skin necrosis and scarring but including allergic reactions and anaphylaxis. Significant amounts are absorbed into the body when DEET containing products are applied to the skin (up to 48% of an applied dose may be absorbed). In 1988 a Lancet editorial drew attention to case reports of severe encephalopathy (brain toxicity) in children following the repeated and extensive application of preparations containing only 20% DEET. They concluded that "the use of repellents containing more than 50% DEET should be avoided in infants and young children" and that "serious consideration should be given to withdrawing all high strength (>75%) preparations from general use". A poisons information monograph on DEET was commissioned by the United Nations Environment Programme, the International Labour Organisation and the World Health Organisation and, in the USA a steering committee was formed to monitor DEET toxicity. New York State attempted to restrict DEET concentration in repellents sold in the State to 30%.

Despite increasing concerns about toxicity, the lack of effective alternatives to DEET made any recommendation to restrict its use or concentration impractical. The potential hazards associated with biting insects were generally held to outweigh the risks associated with the use of preparations containing DEET.

Some natural plant extracts have been reported as having repellent effects. Citronella, for example, has been used in a number of commercial preparations. With the current trend towards natural substances to replace many synthetic chemicals used today it may be that a return to a more widespread use of such "herbal" remedies could prove valuable in many instances.

In response to concerns about DEET toxicity a research team was formed in 1992 led by Dr Paul Clarke with the aim of finding a non-toxic alternative to DEET. The team concentrated on lemon eucalyptus oil as this was known to have natural repellent powers. Under the guidance of the chemistry department at University College, London a variety of eucalyptus extracts were prepared.

Extensive testing using hungry, caged mosquitoes was carried out by Dr Paul Clarke and Dr Peter Barrett and, eventually, a eucalyptus extract with a powerful repellent action was demonstrated. Investigations have shown that naturally occurring lemon eucalyptus extract is the active material. Practical formulations of the derivative were prepared at the London School of Pharmacy and subjected to intensive independent testing both in the laboratory and in the field. Results indicate near equivalence to DEET and clear superiority over citronella and other plant based products such as the Avon branded preparation Skin So Soft.

Lemon eucalyptus extract is not purified, but is used as Citriodiol, with a minimum active ingredient content of 64% lemon eucalyptus extract.

Citriodiol is the active ingredient of a range of products called Mosi-guard Natural (MGN). These products have been shown in the field to be as effective as products containing DEET and to date, following the sale of more than 2 million units, there have been no significant adverse effects. There have been about 6 complaints relating to rash concomitant with MGN application none of which has it been possible to substantiate by reapplication/patch testing. Summaries of the Chemistry and Pharmacy data, Preclinical studies and Efficacy trials are presented on the following pages.

The reported studies show that Mosi-guard Natural is an effective alternative to products containing DEET.

The acute oral median lethal dose (LD₅₀) and 95% confidence limits of the test material were calculated by a probit method of Finney DJ to be:

All animals : 2408 (1914- 3030) mg/kg body weight

Males only : 2454 (1896 - 3175) mg/kg body weight

Females only: 2636 (1470 - 4729) mg/kg body weight

Therefore no symbol and risk phrase are required according to EC labelling regulations.

The acute dermal median lethal dose (LD50) of the test material in the Sprague-Dawley strain rat was found to be greater than 2000 mg/kg body weight. Therefore no symbol or risk phrase are required according to EC labelling regulations.

The test material produced a primary irritation index of 1.2 and was classified as a mild irritant to rabbit skin according to the Draize classification scheme. No corrosive effects were noted.

The test material did not produce positive criteria in any rabbit according to EC labelling regulations and was classified as non-irritant to rabbit skin. No symbol and risk phrase are therefore required.

The test material produced a maximum group mean score of 32.8 and was classified as a moderate irritant to the rabbit eye according to the modified Kay and Calandra classification system. The test material was also classified as irritant according to EC labelling regulations. The symbol "Xi" and risk phrase "irritating to eyes" are therefore required.

The test material produced a 0% sensitisation rate and was classified as a non-sensitiser to guinea pig skin.

The test material is considered to be non-phototoxic.

Citriodiol was found to be non-mutagenic under the conditions of this test.

Mosiguard Natural aerosol spray * was tested for acute inhalation toxicity at a targeted level of 2.0 mg/L of air by exposing 5 male and 5 female rats for a 4 hour period. The actual geometric concentration of the study was 2.06mg/L of air.

The acute inhalation LC50 was found to be greater than an actual geometric concentration of 2.06 mg/L of air for a four hour period. All test animals were alive when removed from the chamber at the end of the 4 hour experiment. All the animals survived the 14 day observation period.

* This was a US formulation at 40% citrodiol w/w.

7. L5178Y TK+- Mouse Lymphoma Forward Mutation Assay With a Confirmatory Assay with Oil Of Lemon Eucalyptus

The test article, Oil of Lemon Eucalyptus, was evaluted as negative for inducing forward mutations at the TK locus in L5178 mouse lymphoma cells under non activation and activation conditions used in this study.

8. In Vivo Mouse Micronucleus Assay with Oil Of Lemon Eucalyptus

The test article, Oil of Lemon Eucalyptus was evaluated as negative in the mouse bone marrow micronucleus assay when administered by intraperitoneal injection under the conditions of this assay.

9. Primary Eye Irritation Study

There were positive eyes irritation reactions in all of the six test subjects and the maximum group Mean score was 22.0/110.0 at the 1 hour observation. There was no irritation present at the 168 Hour observation, therefore the study was ended

The application sites were graded for indication of skin reactions at 4-1/2,24,48, and 72 hours after sample application. The primary dermal irritation index was 0.42.

(Oil of Lemon Eucalyptus is a synonym for Citriodiol)

Dermal administration of Oil Lemon Eucalyptus to rats at the limit dose o 1000 mg/kg/day for a period of 28 days caused an increases incidence and severity of skin reactions characterised by slight erythema, oedema and flaking of the skin at the application site. These changes were confirmed microscopically in the form of hyperplasia and hyperkeratosis of the epidermis; hyperplasia of sebaceous glands and scattered dermal inflammatory cell infiltration. A transient reduction in body weights gain was observed in the Test Substance Group during the first one to two weeks of the study. However, body weight gains were comparable or greater to those observed in the Vehicle Control Gm ups after the first one to two weeks of the study and the absolute differences in body weight were less than 5% at the end of the study. Therefore, the lower overall body weight gains observed in the Test Substance Group were not considered to be an indication of a systemic effect associated with the dermal application of the test substance. A more likely explanation for theses transient reductions in body weight gain is the slight irritant effect that was observed in the Test Substance Group. Based upon the results of this study, the systemic no observed-effect-level(NOEL) for subchronic dermal administration o Oil of Lemon eucalyptus is considered to be greater than 1000 mg/kg/day.

(Oil of Lemon Eucalyptus is a synonym for Citriodiol)

On the basis of these data, the limit dermal dosage of Oil of Lemon Eucalyptus(1000mg/kg/day) caused only minor adverse skin reactions. These localized effects (skin irritation) of the test substance were believed to have caused the small reductions in maternal body weight gain that occurred. No evidence of system toxicity occurred. Absolute feed consumption values were slightly increased in the test substance group, reflecting the lowered weight gain.

Based on the results of this study, the maternal and developmental no-observable adverse-effect-level (NOAEL) for Oil of Lemon Eucalyptus is greater than 1000 mg/Kg/day.

The results of these two studies indicate that PMD is poorly absorbed through the skin and, that what PMD is absorbed, is rapidly excreted in 24-36 hours. The lack of any adverse reaction in the two subjects is an indication of the safety of this insect repellent.

Longevity studies applying the minimum effective dose indicate that reapplication times would be about 4 hours. This is a remarkably long protection period for any natural plant based product, and is very similar to those provided by good DEET based products currently available. As consumer preferred doses are much higher the longer effective periods shown in the field trials were to be expected.

Mosi-guard Natural has also been tested against blackfly, sandfly, midge, tick, biting stable fly and cone-nosed bug. It is highly effective against midges, sandflies and biting stable fly and provides some protection against blackfly. Results in rabbits indicate that it is effective in reducing the risk of tick bites. However both Mosi-guard and DEET were ineffective in repelling cone-nosed bugs.

All formulations were effective in repelling Culex quinquefasciatus, Anopheles gambiae and Anopheles funestus. The degree of repellency towards different mosquito species was not clearly established as the Anopheline data was incomplete due to bad weather conditions prevailing during the trials.

Collectors generally preferred Mosi-guard Natural to DEET, notably the Stick and Roll-On formulations. There was no evidence of skin sensitivity towards Mosi-guard Natural, whilst 3 of our 6 collectors reported skin irritation towards DEET.