Heavy metals form a versatile group of high density elements that vary considerably in their biological roles and chemical properties. Although many heavy metals are essential trace elements yet they have long been recognized as environmental pollutants due their toxic effects. Increased industrialization, urbanization anthropogenic activities like mining, smelting and other agricultural activities have resulted in accumulation of heavy metals in the environment. Heavy metals such as nickel, cadmium, zinc, copper, mercury, arsenic and chromium are not easily degradable and tend to build up in soil. These heavy metals through various routes such as fish and plants make their way into the human body and are known to have serious detrimental effects on human health at elevated levels. The harmful effects of some important heavy metals on human health have been discussed.

Aflatoxins are natural contaminants of cereals and other commodities throughout the world. Chronic dietary exposure even to low doses of aflatoxins is a known risk factor for liver cancer and effect protein metabolism and immunity. The study was carried out on a 1029 samples of brown rice, 1561 samples of white rice, 33 samples of broken rice, 13 samples of Sella rice, 52 samples of parboiled rice of export quality from Pakistan during the years 2006-2010 for determination of Aflatoxin B1, B2, G1 and G2 by Thin Layer Chromatography. 341 (33.13%) samples of white rice, 350 (22.42%) samples of brown rice, 13 (39.39%) samples of broken rice, 25 (24.27%) samples of Sella rice and 14 (26.92%) samples of parboiled rice were found contaminated with B1. B2 was detected in 33 (3.20%) samples of white rice, 23 (1.47%) samples of brown rice and 1(3.03%) samples of broken rice. While G1 is found in 9 (0.8%) samples of white rice, 57 (3.65%) samples of brown rice, 1 (1.5 %) samples of parboiled rice. Aflatoxin G2 was absent in all samples. DOI: http://dx.doi.org/10.3329/bjsir.v49i3.22134 Bangladesh J. Sci. Ind. Res. 49(3), 189-194, 2014

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The antioxidant efficacy of the spinach extract was evaluated by addition in sunflower oil (SFO) as natural antioxidant. Three different concentrations of spinach extract, SFO-800, SFO-1600 and SFO-2400 ppm were supplemented to sunflower oil at 25 o C and 60 o C along with standard synthetic antioxidants butylated hydroxianisole (BHA), butylated hydroxytoluene (BHT). The stabilization of sunflower oil with spinach extract as natural antioxidant was monitored by evaluating oxidation in terms of peroxide value, free fatty acid value, iodine value, conjugated dienes, conjugated trienes and para-anisidine value. Spinach extract with maximum concentration showed significant effectiveness in oxidative stabilization of the sunflower oil.

IntroductionPollution of heavy metals is of major concern in developing countries. The discharge of heavy metals into water-courses is a serious pollution problem which may affect the quality of water supply. Increasing concentration of these metals in the water constitute a severe health hazard due to their nondegradability and toxicity. Copper metal considered in this project is a widely used material. Copper metal contamination exists in aqueous waste streams from many industries such as electronic and electrical, metal plating, mining, manufacture of computer heat sinks, Cu plumbing as well as biostatic surface, as a component in ceramic glazing and glass coloring. Copper is persistent, bioaccumulative and toxic metal that does not readily breakdown in the environment and is not easily metabolized. It may accumulate in human ecological food chain through consumption or uptake and may be hazardous to human health. Drinking water that contains higher than normal levels of copper may cause vomiting, diarrhea, stomach cramp and nausea. The chronic effects of consumption of high levels copper are kidney and liver damage. The suggested safe level of copper in drinking water for humans varies depending on the sources, but tends to be pegged at 1.5 to 2.0 mg/L. Hence removal of copper from water and wastewaters assumes important (Nauja et al. 2008). The effects of various parameters, such as pH of the feed solution, contact time, temperature, adsorbate and adsorbent concentrations, and particle size of the adsorbent, were studied for optimization of the process parameters. The adsorption behavior of Cu on three solid waste materials-sea nodule residue (SNR), fly ash (FA), and red mud (RM) was observed (Agrawal et al. 2004). It was noted that adsorption of copper increased with increasing time, temperature, pH, and adsorbate concentration, and decreased with increasing initial copper concentration. The ability of rice husk ash to remove chromium, zinc, copper and cadmium from waste water has been investigated. Several parameters that can affect metals uptake such as particle size, pH and temperature were described. At the optimal conditions, the chromium, zinc, copper and cadmium ions removal from aqueous solution are 79, 85, 80 and 85%, respectively. After the adsorption of metal ions, the analyte retained in the husk could be recovered almost completely by eluting with dilute hydrochloric acid solution (Munaf et al. 1997). Rice husk was studied as a potential scavenger of lead from various aqueous solutions. Physiochemical parameters such as selection of appropriate electrolyte, shaking time, and the concentrations of adsorbent and adsorbate were studied for the decontamination of effluents using a batch technique (Nasir et al. 1998). The utility of rice husk ash as an adsorbent for metal ions such as iron, zinc and copper from acid mine water was assessed. Study of Chockalingam et al. 2006 revealed that about 99% Fe 3+ , 98% of Fe 2+ and Zn 2+ and 95% Cu 2+ uptake was achieved from acid mine water, with increase i...