Yao Lei

Aromatic Plants R & D Center, Shanghai Jiaotong University, China

Introduction

Essential oils are one of the most popular types of natural therapeutic products. These have been used since long by people all around the world, however, they are now used in many fields including cosmetic, spa,aromatherapy, perfume, food flavors etc, due to their fragrances & excellent and therapeutic properties such as anti-septic, anti-inflammable, and anti fungal properties.

Historically, essential oils have long been used in perfumes, cosmetics, soaps, aromatherapy and other products, for flavoring food and drink, and for adding scents to incense and household cleaning products. As natural spices, the officers lay down the national criterions in essential oil’s types, chemical compositions, physical properties and usages. The supervision departments inspect the market as well.

In recent decades, the aromatherapist training schools from Great Britain, Germany, and France enter the Chinese market. Aromatherapists use the naturally extracted aromas of certain plants to help people deal with the physical and emotional demands of everyday life. They know and understand what the oils do to the body and how the oils can treat certain ailments. Though there is no official certification or degree program for aromatherapy, there are many schools that offer training programs for those desiring to practice aromatherapy. In order to become an aromatherapist, students typically only need certification from an accredited school. However,China’s official does not recognize aromatherapy industry(the aromatherapy industry in some foreign countries belongs to the field of medical auxiliary). Most of these certificate holders work in SPA, Beauty shops, Health clubs, or freelance at home. They provide treatments to their guests through essential oil massage, sniffing, even oral aromatherapy means to help the guests relieve their pains and recover. The market situation of aromatherapy industry in China is disturbing.

This concern is derived from the source of the essential oil itself, the security of the oil, and the qualification of aromatherapists, and the safety of implementations. In Europe and America, the first step to becoming an aromatherapist is to get their qualification to be a doctor, a pharmacist, or a nurse, and then they should receive professional training of aromatherapy.Aromatherapists are not required to be licensed medical professionals, but they may earn optional certification through the NAHA, which requires 200 hours of training and practice in aromatherapy. According to NAHA standards, certified practitioners must also have extensive knowledge of anatomy and physiology. Practitioners with this certification must know about the elements of botany, the medical and holistic properties of therapeutic,chemical blending techniques and methods of oil application. The NAHA has established a code of ethics for aromatherapists, which covers treating clients with holistic principles and sharing knowledge with colleagues.

Around 1990, the concept of aromatherapy began to be accepted in China. It was first introduced to mainland China by a businessman, when the basic application of essential oils and the promotion of its possibilities began to spread. Young women aged 18～25 went to Europe and America to study and experience essential oils, returning to spread their knowledge to others via forums and websites, etc. As herbalism was already well known, aromatherapy was readily accepted. Most buyers of essential oils are over the age of 25, as they can more easily afford them: they are used mostly in vaporizers. Although essential oil use is widespread, there is a shortage of correct aromatherapy information and training in the Chinese language, making aromatherapy less easily available to people generally. Aromatherapy has been identified by the Shanghai Vocational Training Orientation Centre (SVTOC) as an area for growth, an agreement being made recently with the International Federation of Professional Aromatherapists (IFPA) to develop British-style aromatherapy training.

There is no Chinese professional association for aromatherapy. Many people—including the government—class aromatherapy with beauty and hairdressing, and as most practitioners were without any professional training, many mistakes occurred using essential oils,adversely affecting some clients’ health. Because of this,the government introduced an “Aromatic Masseurs Qualification Standard”, which came into force at the end of 2004. Aromatic masseurs have to follow these government recommendations, which will ensure that aromatherapy progress in the right direction. In China,many aromatherapists lack qualified expertise. They also don’t have the background in phytochemistry or botany.Aromatherapy is a type of alternative medicine that uses essential oils to improve a person's health or mood.Interest in aromatherapy grew in the late 20thcentury as a form of complementary medicine. In China, the state standards and regulations on essential oil, including essential oil types which can be used for human body massage, sniffing, and oral products, essential oil’s effects, essential oil’s usage, etc. are not drafted or published. The whole industry is asking for standard certification of aromatherapists and the market also demonstrates its need for professionals.

Definition of essential oil

Essential oil is oil that comes from a plant that smells like the plant it comes from, and that is used in perfumes and flavorings. An essential oil is the essence of a plant.It’s extracted from the leaves, bark, stem, root, or flowers of a plant by a steam distillation process. The oil plays an important role within a plant.

The first records of essential oils come from ancient India, Persia, and Egypt; and both Greece and Rome conducted extensive trade in odoriferous oils and ointments with the countries of the Orient. One of the key properties of essential oils is their extreme volatility —which means that their molecules become vapor (become airborne) very easily. They are so volatile that the current word “essential” oil comes from the Latin word “essentia”meaning liquid that becomes a gaseous essence.

Four animal substances (ambergris, castoreum, civit and musk) are frequently associated with essential oils due to their history as part of the perfume industry. While not essential oils, you should be familiar with their origin and use. They have primarily been used as fixatives—since they have high molecular weight, which prevents loss of the molecules to the air. Thus extending the “l(fā)ife” of the essential oils with which they are mixed.

Essential oils are natural complex mixtures of terpenic and non-terpenic compounds derived from various plant parts. Essential oils are generally extracted by distillation,often by using steam. Other processes include expression,solvent extraction, absolute oil extraction, resin tapping,and cold pressing.

In nature, essential oils play important roles as signaling agents namely in the protection of plants against microorganisms, insects, and herbivores, as attractants of pollinators, and in allelopathic interactions.

The study found that plant essential oils’composition and concentration change under different environmental conditions, and different stages of plant growth. The oil contents of essential oils increase significantly at reproductive stage and under the condition of environmental stress. During a long-term process of co-evolution, the aromatic plants establish a mutually beneficial relationship with all other living creatures.Animals can use migration to escape unfavorable environments, while plants only can produce and release some specialized compounds to protect themselves from predators. Scientists found that aromatic plants often secrete volatile compounds of various terpenes to attract insects for pollination. The insects fly toward the object according to the odor concentration gradient.These volatile compounds are insect attractant, and also known as essential oils. Plants may also produce a lot of essential oils to defense against environmental stresses,pathogens and herbivores. Insects have pollinated flowers for hundreds of millions of years. Insects are attracted to plants for a few reasons: their aroma, their color, or their structure. The aroma is the biggest attractor however, and because the oil gives plants their unique scent, it attracts insects and aids pollination.

The plants secrete essential oils through physical structures such as resin canals and glands. Each plant has specialized epidermal cells that form glands. They are called “Glandular Trichomes”. They are found in almost all plants and are secretory in nature. These glands are found in various parts of the plant ranging from the flowers, peels, berries, leaves, petals, wood and roots,depending on the type of plant and what the purpose for the essential oil will be utilized by that plant. The growth period and surrounding environment will affect essential oils’ quality and quantity.

Acquisition method and characteristics of essential oil

Various extraction methods are used in the manufacture and extraction of essential oils, and the method used is normally dependant on what type of botanical material is being used. The common extracting methods are steam distillation,hydro-distillation, solvent extraction, expression(also called cold pressing), microwave method, molecular distillation,supercritical CO2extraction and so on.

According to above-mentioned descriptions, it is believed that essential oils have the following characteristics:

1) Essential oils are significant active materials that influence the growth of plants, and completion of plants life history. Therefore, essential oils are effective.

2) Yield and compositions of essential oils are affected by the production year and the environmental conditions.The compositions of same species would even be changed due to climate change. Each type of essential oil has a different chemical composition that affects how it smells,how it is absorbed, and how it is used by the body. Even the oils from varieties of plants within the same species may have chemical compositions different from each other. The same applies to plants that are grown or harvested in different ways or locations.

3) Essential oils are highly complex mixtures of volatile compounds, and many contain about 20 to 60 individual compounds, albeit some may contain more than 100 different components. Therefore, the aroma and efficiency of essential oils depend on all compounds, each component has its specific function and components have synergistic effect as well. On the contrary, if a single compound is separated from the oil, the essential oil no longer has any effect to a large extent. If a certain ingredient is cut or restructured, the oil will lose the original function. Although the essential oils have a great number of components, the ones of commercial interest are generally those composed of one or two major components, which provides them with accurate features.

4) Essential oils are so small in molecular size, they can penetrate the tissues of the skin. Essential oils are very volatile, evaporating quickly when they are exposed to open air. Storage methods and time can cause a change in aroma composition.

5) Essential oils are very concentrated and potent.Compared to dried herbs, they are about 75～100 times more concentrated. Even small amounts can cause harm if used improperly. Dilute all essential oils before applying to the skin, either in fatty oil or in water as when used on a compress.

6) In general, essential oils can be subdivided into two distinct groups of chemical constituents: the hydrocarbons which are made up almost exclusively of terpenes (monoterpenes, sesquiterpenes, and diterpenes); and the oxygenated compounds which are mainly esters, aldehydes, ketones, alcohols, phenols,and oxides. Terpenes and terpenoids that contain long chains of alternating C=C double bonds, are the primary constituents of the essential oils of many types of plants and flowers.

Essential oils are volatile compounds that are sensitive to heat, light and oxygen. Most essential oils have a shelf life.

7) Each essential oil has different biological properties and effects, so it has its own unique aroma that different from other essential oils.

8) Some essential oils are banned or restricted as they can negatively impact on your health, and some must be used with care to prevent any problems.

9) The choice of method is important because it will influence the ultimate quality and therapeutic value of the oil. Indeed, each method of extraction gives a different product, as each process extracts different constituents from the plant. For example, the composition of ginger oil obtained by solvent extraction contains many macromolecular substances and pigment, while obtained by steam distillation does not contain these ingredients.

10) The composition of essential oils from natural sources is more likely to be isomer, such as menthol is a major component of peppermint oils. The L (l-menthol)commonly known as menthols extracts different conanesthetic effect on skin and mucous membrane,are used as analgesic and antipruritic, have antiseptic and germicidal effect as well, while the right has no such effect. Currently successful synthesis of dextran on the market is also called the menthol, but the effect is quite different. Therefore, the heterogeneous nature of essential oils cannot be replaced by synthetic perfume.

11) Most essential oils have flash points below 60℃and therefore are flammable liquids.

From the above characteristics of essential oils, it can be understood that flavorists and aromatherapist stand in a completely different perspective of essential oils. Flavorists, also known as Flavour Chemists, are research scientists that are primarily concerned with how to improve the flavour of food and beverage products. To do this, they study how the properties of food ingredients interact with our sensory organs, and apply that knowledge to the development of natural and artificial flavours. While aromatherapist just preserve the component as much as possible to maximize its efficacy. Therefore, in term of the method of crude oil pretreatment, which engineers in the flavor and fragrance industry usually take, cannot be used commonly in the field of aromatherapy.

Functions of essential oil

Throughout history, essential oils were used to cure diseases and relieve symptoms. Many studies of essential oils have found that they have antibacterial effects when applied to the skin. Scientists took common 100 kinds of bacteria and 100 kinds of fungi as the study objects,and it was found that 87 kinds of essential oils from 100 kinds have a certain inhibitory effect in varying degrees for different strains. Some essential oils, such as fennel, niaouli, hyssop, ginger and myrrh, can help sooth inflammation, seasonal allergies, and other conditions;some essential oils such as lavender, tea tree, eucalyptus oil acid, lemon, Helichrysum and thyme, can increase the body's ability to combat infection from bacteria or viruses.

According to more than 10 years study on animal behavior by Aromatic Plants R & D Center of Shanghai Jiaotong University, it was found that some plants such as sweet orange, sandalwood, cedar, cananga odorata,lavender, geranium, lemon, rose, and myrtle, have good effect on anti-anxiety. The combination with sweet oregano, chamomile and lavender can help people fall asleep and stay asleep.

In 2004, Richard Axel and Linda Barker were awarded the Nobel Prize in Physiology or Medicine for their discoveries of “odorant receptors and the organization of the olfactory system”.

In order to prove the specific efficacy of essential oils,many researchers focus their study on the monoterpene compounds and sesquiterpene of the essential oils in order to find their effectiveness expression. Igimi confirmed that limonene can dissolve gallstones. Some researchers confirmed that some essential oils are good at cancer prevention and possible adjuvant therapy.Limonene and perilla alcohol have been shown to be implicated inhibition of different stages and different types of cancers.

The anti-inflammatory effect of sesquiterpene is an indisputable fact. Many studies have found that sesquiterpene lactone is a potent anti-inflammatory agent,it can relieve the itching and inflammation caused by mosquito bites.

Many studies have shown that monoterpene alcohol has strong antibacterial and antifungal effects. It is softer than the disinfectant, and good for the stability of the skin and mucosa. For example, linalool has strong activity against bacteria, geraniol displayed strong activity against fungi, and menthol can against 18 types of bacteria and 12 types of fungi. 4- terpineol, which is the main component of Australian tea tree oil, can stimulate the activity of white blood cells. Some researchers pointed out that the content of monoterpene alcohols in marjorams is up to 50%, and it can help boost immunity system, regulate endocrine, and relieve fatigue.

Scientists have proved the viridiflorol, cedrol and santalol in sesquiterpene alcohols can enhance the function of vascular and cardiac. Dr. Pennel proved anticonvulsant and sedative effects of esters. He proved that both esters of benzoic with 7 carbon atoms and acetate with 2 carbon atoms have a strong effect on anticonvulsant acetate. Because esters are comes from sterols. In generally, the esters from sterols with shorter carbon chains have a psychological effect. In the later stages of metabolism, monoterpene esters, such as orange blossom esters, are produced. The esters which is converted by sesquiterpene alcohols during the early stages of sesquiterpene esters’ metabolism, have effects on genitals. Ruchbauer studied the effect of linalool and linalyl acetate in 1991. He found that both have a calming effect on mice, and proved that they have inhibition of the motor cortex. Dr Pennel found that if appling rome chamomile oil to the chest and neck before surgery,they release their sedative effects on patients. This is because rome chamomile contains a large number of ester compounds. There are lots of essential oils’ research results are published.

Essential oils safety

The importance of planting and processing

The safety of the essential oils is the most important topic, and it is also a complex topic, which involves in planting, processing, and sorting, etc.

First of all, the essential oils safety depends on the growth process. For example, using of chemical fertilizers during the plant growth process can cause essential oils contain unsafe substances.

Second, solvent extraction has been widely used to extract essential oils. Solvent extraction methods of essential oils have some disadvantages, its contamination with solvent or solvent residues and the pollution of residual vegetal material with solvent which can be also an environmental problem.

Correct essential oil storage is important. Never store essential oils in plastic, since they are corrosive and will eat away at the container. Air and oxygen, moisture, light and high temperature will deteriorate the quality of an essential oil.

The safety of essential oils

Most essential oils are safe and free of adverse side effects when used properly. Some scientists have also expressed concern about the possible safety problems when essential oils are absorbed by the skin. The study found that the compounds can enter the blood stream and circulate to other areas of the body after being absorbed into the skin. The penetration speed is related to the size of molecular weight and the lipid solubility.

There are reports pointed out that some ketones,esters and aldehydes can led interfere with hemoglobin—based function when they penetrate into blood. Especially,an excessive amount of accumulated ketones in the liver can lead to liver poisoning. Ketone hydrocarbons are neurotoxic, and all essential oils containing ketones should be avoided in situations that require long term use. For example, pulegone, a monoterpene ketone, is a major component of pennyroyal oil. Ingestion of high doses of pennyroyal oil has caused severe toxicity and occasionally death. Camphor is a bicyclic monoterpene ketone found widely in plants. It has been shown in studies that essential camphor oil has an adverse effect on the central nervous system. The symptoms of camphor intoxication are miosis, tachycardia, and rapid breathing.Symptoms of Camphor Poisoning may include headache,hallucinations, nausea, vomiting, diarrhea, convulsions,and kidney failure.

In addition to ketones, some aldehydes also may cause problems. Cinnamon does not cause health problems when it's consumed in the amount typically found in foods. On the other hand, it does have active ingredients that can cause side effects, especially in concentrated forms. But cinnamon oil can cause a burning sensation when it's applied directly to skin.

“Natural” or “standard” doesn’ t mean “safe”

Essential oils are the natural products of plants. As we known, nature products can be influenced by the environment, so the products are different in different years, even in different batches. Therefore, in order to stably meet the needs of the market, the different producers developed their own standards based on the chemical components of essential oils. These standards indicate the variation of the chemical composition and physical properties of the essential oil. Of course, the standards should be submitted to the state relevant departments and put on record. Generally speaking, in the premise of a stable climate, varieties, cultivation methods,harvest time, extraction method, sorting method, packing method, the tolerance is included in the scope of the standards. But it's often the case that some components are below or above the standard. The technicians will adjust products according to the standards by mixing with its storage, thus, they can control products quality in a stable level. The national standards of essential oils refer that the relevant national departments develop the common standards of essential oils on the basis of the producers’standards of domestic enterprises. The national standards will be used in the international trade. The national standards mean essential oils meet China's standards.Essential oils are widely utilized as flavoring and aromatic agents across diverse end-use industries including medical, food & beverages, spa & relaxation, cleaning &home, etc. These oils provide immense nutritive value to food and increase the overall appeal of products with just a few drops. Essential oils can be blended with spices to make fragrances or function products. The fragrances are used in food, cleaning products and cosmetics in a small amount. When the essential oils are used in aromatherapy or for human daub, massage, and inhalation, the usage quantity of essential oils are always much higher than the flavoring products.

Problems caused by chemotype of essential oil and improper use of essential oils

Essential oil chemotypes are produced from the same plant species but have different chemical components.Essential oils extracted from the same plant species may look the same but chemically they are different.An essential oil chemotype is derived from a plant that has the same visual appearance and characteristics but it is chemically composed of differing components.An essential oil chemotype has different therapeutic properties due to the presence of different chemical components; for example, one chemotype may have a higher content of alcohols compared to another chemotype that may have a high content of phenols.Chemotypes are present in both wild and cultivated plants.

For example, several chemotypes of thyme, based on essential oil compositions, have been established,including: linalool; borneol; geraniol; sabinene hydrate; thymol; carvacrol, as well as a number of multiple-component chemotypes. The most abundant compound in thyme essential oil is usually thymol,which can cause skin irritation. One of the chemotypes of thyme essential oil is called c.t. (for chemotype)linalool, which is gentler than other well-known thyme chemotypes such as thyme thymol. Rosemary essential oil has 3 principal chemotypes: camphorborneol, 1,8 cineole, and verbenone. Due to differences in composition, each chemotype will have maximum efficacy in differing applications. The camphorborneol chemotype is best suited as a general stimulant and is also suitable for muscular aches and pains.This oil, 1,8 cineole chemotype, is best suited for the respiratory system and aiding in the detoxifying of the liver and kidneys. It has a lower ketone content than the verbenone chemotype and is the more common for use as an anti-microbial ingredient. The verbenone chemotype is best suited for strengthening the liver and gall bladder. Rosemary verbenone is considered the most gentle and non-irritant of the rosemaries,which is why it is included in so many skin care blends.Chemotype when used incorrectly can cause serious problems.

Clove oil contains highest eugenol. Clove oil is a potentially dangerous substance. It can do more in our body than simply damage tissue. The ingestion of a large quantity of the oil can cause a coma, seizures,liver damage, and kidney damage. Other detrimental effects of clove oil include nausea, vomiting, stomach pain, diarrhea, and a rapid heartbeat. Some chemical components in essential oils can cause skin rashes and stimulate the immune reaction.

Phototoxicity has received increased attention in recent years. Photosensitization is the process in which ultraviolet (UV) radiation combines with a particular substance and causes chemical or biological changes.Some essential oils contain furocoumarins, a special class of constituent that can cause photosensitization of the skin. Inflammation, blistering and reddening/burning of the skin are common. The most commonly found furocoumarins in essential oils are bergapten and oxypeucedanin. The chemical structure of these molecules (and their metabolites) allows them to form cross-links with skin cell DNA, in turn making the skin especially susceptible to UV radiation. During the process, free radicals and singlet oxygen are also formed and can inflict damage on cellular membranes,organelles, and proteins. If exposed to sunlight (which gives off UV radiation) after topical application of the photosensitive oil, the skin may become temporarily darkly pigmented, red, or irritated. Photosensitivity and phototoxicity apply to topical use of essential oils only and do not pose the same risks when used internally.When using a photosensitive essential oil topically,avoidance of sunlight is recommended for up to 12 hours after use.

Man-made and security risk

1) Cultivation of spice plants commonly involves the use chemicals such as fertilizers and pesticides.

2) The unnatural components are added to essential oils. For aromatherapy, we should only be using essential oils that are botanically pure.

3) When stored correctly essential oils can last an extremely long time. Over time, or without proper preservation, however, essential oils can oxidize,deteriorate and gradually lose their therapeutic.

4) A therapeutic-grade essential oil is the one that is complete in its chemical compounds and also retains the innate coherent vibrational frequency of the original plant materials. This is important, because the oil's fragrance, frequency and chemistry all contribute to its unique therapeutic effects. If any of these properties is compromised, as a result of poor production practices, an essential oil will have little to no therapeutic value.

How to assure the safety of essential oils

1) Controlling the safety of essential oils from its start. In cultivation process, the species should firstly be selected. And then carrying on organic cultivation or controlling the use of agricultural fertilizers. In the extraction process, organic solvents should not be used. Such as the safety of essential oils from the source control.

2) Essential oils storage. Most essential oils can be safely used for 1～2 years or more after opening.Refrigeration is ideal for oil storage. Keeping the oils in a refrigerator will protect them from sunlight, reduce the chances of air exposure, and help keep the oil stable in the cooler temperature. This can prolong the guarantee period 2 times. Some essential oils, which are easily deteriorated, should be used up within 6 months after the purchase (refrigerated within 12 months). Please pay attention that cold temperature will increase the viscosity of essential oils.

3) Packaging and labeling. Store essential oils in dark glass bottles. The essential oil labels need to include common or usual name of the source plant,chemotype, purity identification, extraction methods,the country of origins, extraction parts of plant, net contents (including metric measurements), name and address (of manufacturer or distributor), batch number,safety recommendations, an expiration date or date of manufacture, expiration date, ingredient list, usage instructions , and usage cautions.

4) In order to essure the safety of essential oils, it is strongly advised that a skin patch test before using any essential oils for the first time should be performed. Apply a small amount of essntial oil to the inside of your wrist or elbow and leave uncovered for 24 hours.This area must not be washed for this period of time. If no sign of itching,redness or swelling occurs after the 24 hour period, it should be safe to use the oil. It would be advisable to first do a skin patch test using any essential oils.

5) It is important to note that most essential oils cannot be applied directly to the skin (without being diluted). As you can see, there are safety concerns associated with improper use of essential oils. In general, however, essential oils are safe when used externally (not ingested) in low concentrations. For skin applications, that usually means concentrations no higher than 5%.

6) Essential oils are the distilled volatile aromatic constituents of the plant that are highly concentrated.Remember that one drop of essential oil is equivalent to 15～40 cups of medicinal tea, or up to 10 teaspoons of tincture.

Common usage problems

Storage conditions

Essential oils should be packaged in dark colored glass bottle. Essential oils do not like extreme, or repeated changes in temperature, and when not in use should be stored in a cool dark place, away from direct sunlight and other sources of variation in temperature. Never leave oils in a place where the sun will shine directly on.

Shelf life

Essential oils do have a shelf life. First, the expiration date should be clearly marked on the label. Apart from a few exceptions, all steam distilled essential oils have a shelf life of at least 2 years, and even more when stored properly. Opening the jar frequently, leaving caps off for a length of time, placing in sunlight (or artificial light),keeping in a warm place, and getting water or other things in the essential oil bottles can drastically shorten shelf life. In general, shelf life is determined by the chemical composition of the essential oils, some of which oxidize or evaporate more quickly than others. Essential oils which contain a lot of monoterpenes or oxides have the shortest shelf life, of approximately 1～2 years. Essential oils which contain a lot of phenols may last up to 3 years. Essential oils which contain ketones, monoterpenols, and/or esters have a shelf life of 4～5 years. The potentially longestlasting essential oils contain lots of sesquiterpenes and sesquiterpenols which can last up to 6 years.

In Case of Emergency

If essential oils accidentally apply on the skin,generously dilute the area with vegetable or carrier oil,and wipe off. Repeat as needed. You may need to dilute and wipe the oil off several times. Do not use water. It spreads the oils and may cause the oil to penetrate more quickly. If this does not provide relief, contact a health care professional.

If essential oils accidentally get into the eyes,immediately dilute and remove the oil by gently dabbing your eye with a cotton ball, washcloth, or tissue that has vegetable or carrier oil on it. Do not flush the eyes with water. It can increase irritation and spread the oils.If this does not provide relief, contact a health care professional.

If an infant or child, accidentally drinks or swallows essential oils, immediately have them drink an oil soluble liquid such as milk, soymilk, rice milk, yogurt, or cream to dilute the swallowed oils. Seek emergency medical attention if necessary.

Aromatherapy can be a great benefit during pregnancy and assists in minimizing some of the discomfort and aches. There are however some compounds in certain essential oils that have hormone-like behavior because of their molecular structure and although there is no conclusive evidence on the effect of estrogenic oils, it would be prudent to avoid anethole rich oils, like fennel and aniseed during pregnancy. Some essential oils are however not toxic, but have emmenagogue action, which is to help to promote and regulate the menstrual flow (periods), and should be avoided during pregnancy. Can pregnant women use essential oils? There is a positive effect for essential oils on vomiting, backache, edema, during their pregnancy. But some essential oils can induce abortion because of their emmenagogue, such as sweet basil, juniper, basil, rosemary,oregano, sweet cedar, peppermint and thyme. It is best not to use any essential oils in the first 4 months of pregnancy.Smelling is allowed.

We must first remember that essential oils are powerful compounds and that although they are natural extracts from various botanical material, they are highly concentrated, and should never be left where children can get hold of them. Children are particularly sensitive to aroma and products applied to the skin. Don’t use essential oils on or around babies, due to their thinner skin and immature immune systems. After the age of 2, a very low dilution can be start topical used with, but keep in mind a child's immune system takes years to fully develop, making them less able to deal with the adverse affects which may arise when concentrated products are used improperly on or around them. However, if it is a necessity, the fully diluted oil, extracted from the seeds or the fruits, or the fully diluted aromatic plant water can be used.

If you want to use aromatherapy in the room,the types of essential oils are important. Lavender,eucalyptus oil, Chinese citrus, Australia tea tree will be recommended. Meanwhile, children’s age is also an important key. The oils’ concentration must be controlled below 0.5%～1%.