1.1 Background of the study
The world has witnessed considerable changes advancement in technology and industrialization recently. Electrical and electronic equipment has been produced to meet the economic demand of the teeming population. These appliances have infiltrated every aspect of our lives and providing our society with more comfort, health and security and with easy information acquisition and exchange. Unfortunately, these electrical and electronic goods were made from over 1000 chemicals which are toxic to both man and his environment. Most of these electrical and electronic gadgets were made with short lifespan and are quickly outdated with the production of newer ones hence old ones are discarded as waste. The large volumes produced and the short lifespan of electrical and electronic goods makes it the fastest growing waste stream globally (Betram et al., 2002).
The population exposed to potentially hazardous substances through inappropriate and unsafe management practices related to disposal and recycling of end-of-life electrical and electronic equipment, collectively known as e-waste, is increasing. E-waste include all secondary computers, entertainment device electronics, mobile phones, and other items such as television sets and refrigerators, whether sold, donated, or discarded by their original owner. The constituents of E-waste that are hazardous to man include; polychlorinated biphenyls, tetrabromo-bisphenol-A, chlorofluoro carbons, polyvinylchloride, dioxins and furans. Potential toxic metals include lead, cadmium, chromium, mercury, copper, manganese, nickel, arsenic, zinc, iron, and aluminium (Jinhui et al., 2011).
These E-wastes are generated from the developed countries like USA, UK, Germany, Switzerland, Taiwan and Japan. Several million tonnes of these wastes are generated every year. A survey from Western Europe showed that 6million tonnes of E-waste were generated in 1998 and expected to increase by at least 3-5% annually (Cui and Forssberg, 2003). These wastes end up in landfills and incinerators. The incineration of these wastes release toxic metals into the atmosphere as fly ash, while in landfills, they leach into the environment and into water bodies. To tackle the problem of these wastes, these countries export it down to developing nations like Nigeria since this is more economical to them.It is estimated that over 500 containers of second-hand electronics are imported to Nigeria every month from Europe, with each container holding several hundreds to thousands of computers and other e-waste devices (Aragba-Akore, 2005). The developing nations in a bid to bridge the gap in technology readily accept these wastes. Furthermore, the people prefer to buy these second-hand electrical and electronic goods since they are poor. The labour cost for reparation and refurbishment has led to a strong electronic re-use market in the developing countries including Nigeria. Unfortunately, developing nations do not have the technology to recycle these wastes. They use primitive techniques without or with very little technology to minimize exposure to the hazardous components of E-waste (Wong et al., 2007).
People working directly with E-waste are majorly exposed to the dangerous chemicals and toxic metals in E-waste. Burning of the components of E-waste release these chemicals and metals into the atmosphere. On the other hand, these metals leach into the soil and surrounding water bodies which accumulates in aquatic animals. Therefore, people are exposed to e-waste materials and associated pollutants through contact with contaminated soil, dust, air, water, and food sources, including meat (Robinson, 2009).
Beyond the environmental degradation concerns, the hazardous materials found in electronic wastes pose a significant risk to human health. People who break electronic wastes open often suffer radiation, nausea, headaches, respiratory failure among other health problems. However, it is not only the people working directly with electronic wastes who are susceptible to the harmful effects of e-waste but also people living in the ambience of the waste dumps and those indirectly affected through resulting contamination of the food chain, soils and rivers. These people are exposed to the hazardous substances through dermal contact, dietary intake, dust inhalation or particle intake, with the latter two sources found to be particularly significant. Exposure to chemicals from e-waste – including lead, cadmium, mercury, arsenic, polybrominated biphenyls and other persistent organic pollutants – could injure the human brain and nervous system (Dietrich et al., 2011; Guilarte et al., 2012), distress the kidneys (Hellstrom et al.,2001) and liver (Sauer et al., 1997; Liu et al., 2000), and lead to birth defects (Wu etal., 2012). The Minamata disease in Japan between 1954 and 1965; the Love Canal incident, near Niagara Falls in the US; the Koko incident of 1988 in Nigeria; the Zamfara lead poisoning in Nigeria; the Thor Chemicals diseases of the early 1990s in South Africa; the disastrous Trafigura dumping of hazardous wastes incident in Ivory Coast, in 2006, are among the numerous pointers to the grave consequences that unscrupulous waste dumping could have on human beings jeopardizing their livelihood, liberty and very existence.
The liver is the largest viscera organ of the body. It is located inferiorly to the diaphragm and upper right of the abdomen. It is richly supplied with blood and connects with the gastrointestinal system through the portal vein. It is the metabolic hub of the body. The liver is a natural chemical factory which aids in anabolism of complex molecules such as proteins, glycogen, hormones and blood clotting factors from simple substances absorbed from the gastro-intestinal tract. It neutralizes toxins and manufactures bile which aids fat digestion and removes toxins through the bowels (Buraimoh et al., 2011).
Continuous exposure and intoxication of liver to different types of exogenous compounds on a daily basis may lead to hepatic dysfunction (Nithya et al., 2012). Toxic metals are known to cause liver damage and when this is fully established impairs its functions. Most of these toxic metals such as arsenic, copper, mercury and iron are hepatotoxic (Feroz and Nahida, 2012). Cadmium has also been described as hepatotoxic because it causes peroxidative damage to membrane of cells of several organs including the liver, thus leading to liver necrosis (Remugadev and Prabu, 2010; Murugaveh and Prari, 2007). In another investigation done by Sharma and Pandey, (2010), lead was also observed to be hepatotoxic.
The various mechanisms by which these toxic metals from E-waste cause hepatotoxicity ranges from interference with the cell membrane of hepatocyte, generation of reactive oxygen species, lipid peroxidation (Gurer and Ercal, 2000), depletion of glutathione (Gurer et al., 1998), inhibition of antioxidant enzymes by displacing the metal co-factor in these enzymes and blocking the mitochondrial permeability for instance mercury (Nilcolli et al., 1995).
1.2.0Justification for the Study
Nigeria like other developing nations has been legally or illegally importing these E-waste and we have no technology to fully recycle them. More so, the people working with E-waste do not have any protective materials to reduce their exposure to toxic components of E-waste. Hence they are perpetually exposed. The indiscriminate disposal of these wastes poses danger not only to the workers but also people living some distance away as these become pollutants to the environment. Much work on the dangers of E-waste has been carried out places like China and India. Hence, this study in Nigeria is important.
1.3.0Aim of the Study
This study aims at evaluating the hepatocellular function of E-waste workers in Nigeria who are exposed to toxic metals and compare them with those exposed individuals.
- To evaluate the liver enzymes in people exposed to toxic metals in e-waste and compare them with those that are not or minimally exposed by estimating the serum levels of activities of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and gamma glutamyltransferase.
- To evaluate the biosynthetic capability of the liver by estimating serum total protein and albumin.
- To evaluate the biotransformation function of the liver by estimating serum bilirubin.
Chronic and persistent exposure to toxic metals in E-waste could cause deleterious effects on the liver.
Chronic and persistent exposure to toxic metals may not cause deleterious effects on the liver.
1.6.0Scope of Study
The present study evaluates the hepatocellular status among WEEE workers in Benin City, Edo State, Nigeria.
1.7.0 Informed Consent
Individuals who participated in this study are those who gave their personal informed consent, having adequately understood the nature and objectives of the study and have completely filled a questionnaire to this effect.
1.8.0 Ethical Approval
The protocol for the work has been submitted to the Ethical Committee School of Basic Medical Sciences awaiting approval.