CHAPTER ONE
INTRODUCTION
1.1 Background of study
Cosmetology which include nail
and hair care has become a lucrative profession. (Halliday-Bell et al., 2009).

The use and application of cosmetics have been shown to have some effects on the human system.

There are about 9000 chemicals ingredients found in cosmetic products (Kersemaekers and Roelveld, 1995).

Nail and hair care users have daily contact with cosmetic products and are therefore routinely exposed to a wide range of chemicals by inhalation, skin contact and diffusion of fumes through the pores of the eyes (Halliday-Bell et al., 2009).

Hairdressers use a wide range of products, including shampoos, hair dyes, hair sprays, straighteners, and bleaches.

Hair dyes represent the largest segment of chemical products in the hair market today. As such, they are the main source of chemical exposure among hairdressers and heavy cosmetic users (Ronda et al., 2009).
These products may play a positive role in improving quality of life, due to the human desire to improve appearance, however, individual’s frequent contact with these products requires the ingredients be safe (Nohynek et al., 2004).
Nail polish is one of the products most often used by cosmetologist and the main potential source of chemical exposure for heavy cosmetic users.

Common nail polish ingredients include toluene, plasticizers (dibutyl phthalate), and formaldehyde (U.S. Food and Drug Administration, 2013).

Toluene is a widely used industrial solvent.

Toluene inhalation during pregnancy has led to neonatal defects, including intrauterine growth retardation, premature delivery, congenital malformations, and postnatal developmental retardation (Donald et al., 1991).

Dibutyl phthalate, which keeps polish from becoming brittle and chipping, has been linked to reproductive issues in humans if the mother is exposed while pregnant and has been banned for use by the European Union (Pak et al., 2011).
Most young female students handle nail polishes and shampoo, and they frequently assist each other in carrying out makeovers, this dual roles increase exposures to these products (Halliday-Bell et al., 2009). Hairdressing has been reported to be associated with a variety of health issues, including dermatitis, cancer, and respiratory problems (Ronda et al., 2009).

In ameta-analysis of 42 studies, a statistically significant increased risk for bladder cancer was found among people who handles a wide varieties of hair care and facial care products with heavy cosmetic users, specifically those who had been using the products for more than 10 years being affected (Harling et al., 2010).
Alternatively, a review conducted by Nohynek et al.

(2004) concluded that evidence suggests that exposure to hair dyes poses non-carcinogenic or other human health risk exposure to high doses of Diethanolamine (DEA) which is an ingredient found in soaps, cleansers and shampoos has been found associated with liver cancer, and precancerous changes in thyroid as well as mild and eye irritation (Turkoglu and Sakr, 1999).
Parabens which is used as a preservative in cosmetics has been found to interfere with hormonal function causing endocrine disruption (Darbre and Harvey, 2008).

Long term exposure of high doses of BHT (Butylatedhydroxytoluene) used as preservative in moisturizers has been found toxic in mice and rat causing kidney, liver and thyroid problems (Bauret et al., 2001).
According to the US FDA, cosmetic products and their ingredients are not subject to regulation prior to their release on the market.

Also in Nigeria, government policy regarding cosmetics ingredients is poorly regulated.
Therefore, toxicological and biochemical studies of these exposed subjects is necessary for proper knowledge of the effects of constant exposure to nail and hair care products associated with the users and even those who may pick the act of cosmetology as a part time profession, hence ensuring adequate handling of these products and reducing hazards associated with these products..
1.2 Justification of Study
There is increasing repertoire of cosmetic products into the Nigeria market legally or illegally without ascertainment of the level of their toxicity.

Also, there has been a paucity of information in our locality on the effect of cosmetics borne toxicant.

This study therefore will provide clinical insight into the effect of heavy cosmetic usage on liver and renal function parameters of undergraduates in Kwara State University, Malete, Nigeria.

1.3 Aim of Study
This study aimed at evaluating the levels of some selected trace metals, renal function parameters and liver function parameters of heavy cosmetics users among female undergraduates and compare levels with non-cosmetic users.
1.4 Specific Objectives
The specific objectives of this study include:
i). To determine levels of urea and creatinine, sodium (Na+) and potassium (K+) of heavy cosmetics user among female undergraduate and compare levels with non-cosmetic users.
ii). To determine levels of total protein, Albumin, Aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP)of heavy cosmetics user among female undergraduate and compare levels with non-cosmetic users.
iii). To determine levels of copper and zinc in heavy cosmetics user among female undergraduate and compare levels with non-cosmetic users.