Academic journal article Iranian Journal of Public Health

Heavy Metals Uptake of Water Mimosa (Neptunia Oleracea) and Its Safety for Human Consumption

Academic journal article Iranian Journal of Public Health

Heavy Metals Uptake of Water Mimosa (Neptunia Oleracea) and Its Safety for Human Consumption

Article excerpt

Introduction

Heavy metals pollution has been studied and re- ported all over the world (1). Its bioaccumulation and the toxicity allow us to classify them as pollu- tants. Heavy metals are non-biodegradable ele- ment and persist in the ecosystem (2). The accu- mulation of these metals and indestructible ele- ments were related to various human activities such as burning fossil fuels, rapid industrialization, mining and smelting, sewage sludge contents, us- age of chemical fertilizers as well as existence in pesticide and herbicide residues. Different heavy metals may exert different harmful effects that can cause a potential risk to human health. Diseases caused by heavy metals are almost untreatable due to irreversible effect towards biological systems as they can accumulate in body tissues. The pollution of heavy metals to our ecosystems is a warning to humankind about the importance to prevent the ongoing metals pollution (3-6). The use of appro- priate treatment technology in industry is needed to solve the problem of water pollution. At pre- sent, water pollution treatment technology such as chemical precipitation, ion exchange, reverse os- mosis and evaporation method require sophisti- cated instrumentation, skilled personnel, and high cost. Hence, the use of biological system such as phytoremediation has been an emerging method to remove heavy metals because they are simple, cheap and safe for environment. The use of plants to degrade, assimilate, metabolize, or detoxify contaminants is cost-effective and ecologically sound (7, 8).

The application of water mimosa ÇNeptnniaoleraceà) as a biological treatment in phytoremediation of wastewater has developed rapidly. For example in Thailand, this biological treatment is widely em- ployed rather than chemical and physical treat- ments as it uses natural processes and is unlikely to leave toxic substances (9). In addition, some kinds of aquatic plants such as water mimosa, java weed, morning glory and reeds, grow naturally in reservoirs or in the wastewater wetland. As a con- sequence, the utilization of these aquatic plants especially water mimosa to treat the effluent is of particular interest. The characteristic of water mi- mosa that can be grown all year round become one of the benefits in phytoremediation. This technique is found to be simple, cheap and usually high efficiency is obtained (10).

Instead of being used as phytoremediation to treat wastewater, the leaves and young shoots of water mimosa can be eaten raw or cooked (added to soups). This has made a cultivation of this plant as aquatic vegetables became an important activity that sustains the livelihoods of community around the wastewater wetland in some countries. Water mimosa has been consumed by people from Ma- laysia, Thailand and Cambodia due to its nutri- tional values. This plant has high calcium content and plays a crucial role in metabolic processes of living cells, DNA repair and in production of natural steroid hormone (11). For instance, in Phnom Penh (Cambodia), large water surface are- as are overgrown with water morning glory and to a lesser extent with water hyacinth and water mi- mosa. There were extensive human contacts with the water during the various production activities where women and children living nearby often harvest the plants and make bundles, which are collected by middleman with a truck on a daily basis and being sold at the market (12).A study by the Ministry of the Environment of Cambodia estimated that 20% of the total daily vegetable consumption of Phnom Penh comes from these aquatic vegetables in the waste water lake within the city (13). A previous study found high metal concentrations in wastewater sludge especially lead and mercury, which is not surprising as the untreated effluent of more than 3000 industries drains into this wastewater lake. Therefore, this wastewater fed aquatic vegetables despite their potential health risks, they are very important in supplying the city's vegetable markets and thus meeting the demands of the growing population of Phnom Penh (12, 13). …

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