1.0 Introduction
1.1 Background of Study
Henna is a plant. The leaf is used to make medicine. Historically, henna has been used for severe diarrhea caused by a parasite (amoebic dysentery), cancer, enlarged spleen, headache, jaundice, and skin conditions. These days, people take henna for stomach and intestinal ulcers. Henna is sometimes applied directly to the affected area for dandruff, eczema, scabies, fungal infections, and wounds.
In manufacturing, henna is used in cosmetics, hair dyes, and hair care products; and as a dye for nails, hands, and clothing. People also use henna on the skin as temporary “tattoos.”
Henna (Lawsonia inermis) had been used as a hair colorant and decorative medium for long time (Kumar et al., 2005). Hair is a filamentous outgrowth of protein, whose main component is keratin (Harrison et al, 2003). Hair color is the result of pigmentation due to the existence of the chemicals eumelanin and pheomelanin. The hair coloring agents market is dominated by cosmetic companies mostly marketing chemical based colors (Bolduc et al., 2001). It is an accepted fact that all chemicals have some side effects, convincing more discerning customers to use herbal based substitutes; that’s why it was accepted that scientists and cosmetologist made use of henna as a chemical substitute for making hair colors (Charles, 1986).
Henna contains a wine-red dye molecule, lawsone (2-hydroxy-1,4- naphthoquinone) (Lekouch et al., 2001), which makes it useful for dying of hair, as well as colouring of palms, fingers, and soles by binding with proteins (Cartwright, 2006). Henna paste is prepared by drying the henna leaves and grinding them to powder, and then mixing it with oil or water to form a paste. When this henna paste is applied to the skin the dye (lawsone) migrates from the paste to the outermost layer of the skin; more lawsone will migrate more if the paste is left on the skin for a longer time, thus creating a red-brown stain. Additionally, henna plant extract and essential oils can be used either in its concentrated or diluted forms and mixed with another materials in industrial products (Roy et al., 2005).
Besides its use in cosmetics, the henna leaves are used as a prophylaxis against skin diseases (Ahmed et al., 2000), and the stem is reported to be useful for jaundice, enlargement of the spleen (Kirtikar et al., 1956), and skin diseases (Satyavati et al., 1987). It is used also in therapy with oral administration, where the infusion of leaves is used in treating diarrhoea, renal lithiasis (Bellakhdar, 1997) and, abdominal pain (Lahsissene et al., 2010).
Seeds have been reported to have deodorant action and are used in cases of menorrhagia, vaginal discharge and leucorrhoea (Zafar et al., 2006). Analysis of the chemical composition of Henna leaves indicates the presence of the active dye lawsone (2-hyroxyl,4-naphthaquinone), 1,2 dihydroxy coumarine, xanthones, flavones, flavanoids, gallic acid, steroids, tannic acid and light essential oils rich in phenols (Bernth et al., 2005).
Para-Phenylenediamine (PPD), a derivative of Para-nitro aniline is widely used in hair dye formulations, in dyeing furs and in some industries (Anuradha et al., 2004). It has also been used to deepen the color of henna and to accelerate the coloring process. Local application of PPD in vulnerable individuals may result in dermatitis, asthma, arthritis, lacrimation, exophthalmos or even permanent blindness when applied to the eyes. Oral ingestion of PPD might be fatal and results in renal failure, severe edema of face, tongue, neck and laryngeal edema with respiratory distress often requiring emergency tracheostomy (Yagi et al., 1991).
1.2 Statement of Problems
The study reveals the following problems associated with the determination of heavy metal in henna;
- Lack proper estimation of the heavy metal in henna,
- Inadequate information relating to the adverse effect of using heavy metal in henna,
- Lack of proper and precise information relating to the determination of heavy metal in henna.
1.3 Aim and Objectives of Study
The aim of this study is to identify and determine the heavy metals in henna. In achieving this aim, the following specific objectives were laid out as follows:
- To estimate the heavy metal in henna,
- Provision of information relating to the adverse effect of using heavy metal in henna,
- To provide information relating to the determination of heavy metal in henna.
1.4 Significance of the Study
This research work when completed and implemented it will help in the determination of heavy metal in henna and also it will provide information relating to the determination of heavy metal in henna.
Besides, the study will serve as reference material for subsequent researcher in the field or related topics.
1.5 Scope of Study
The study focuses on the determination of heavy metal in henna.
1.6 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).
1.7 Definition of Technical Terms
Henna: Henna is a dye prepared from the plant Lawsonia inermis, also known as the henna tree, the mignonette tree, and the Egyptian privet, the sole species of the genus Lawsonia.
Heavy: heavy simply means having great weight.
Metal: a metal is an element that readily forms positive ions (cations) and has metallic bonds. Metals are sometimes described as a lattice of positive ions surrounded by a cloud of delocalized electrons.
Determination: is defined as a firm intent or a decision which has been reached. An example of determination is the strength to keep applying for jobs after being turned down by dozens of potential employers.
Lawsonia: Lawsonia inermis, also known as hina, the henna tree, the mignonette tree, and the Egyptian privet, is a flowering plant and the sole species of the genus Lawsonia.
Genus: a principal taxonomic category that ranks above species and below family, and is denoted by a capitalized Latin name, e.g. Leo.
Heavy Metal: Heavy metals are generally defined as metals with relatively high densities, atomic weights, or atomic numbers.
