The study and application of health risk assessment techniques are crucial in order to understand the risk of exposure to heavy metals and other harmful pollutants. It entails evaluating the risks of exposure at various concentrations and with reference to certain standard values approved by World Health Organization (WHO) and United States Environmental Protection Agency (USEPA). Investigation of water contamination with heavy metals has become the prime focus of environmental scientists in recent years. Effluent discharges into aquatic system affect living organisms within the receiving environment. The concentrations of these metals were mostly assessed at 50th, 75th and 95th percentile and various exposure evaluated. This review covers studies in water, air, soil and fish samples. Air risks assessment was not given the needed attention and children were more susceptible to the hazard than adult, especially lead toxicity, resulting in health complications. Heavy metals bio accumulates over time, and lethal upon exposure at low concentrations. This review will assist risk managers to minimize the exposure at optimum level as well as for the government to formulate policies in safe guarding the health of population. Key words: Health risk assessment, pollution, heavy metals, water, air, soil.

Threat posed by the heavy metals has been increasing globally rendering many water bodies unfit for human consumption. This could be due to the increase in concentrations of these metals above natural background. This article reviews the literature data on variation of water quality in rivers, lakes, and ex-mining ponds in Malaysia and other selected countries. World Health Organization (WHO), United States Environmental Protection Agency, and Malaysian water quality standards (INWQS) are used as the baseline for the pollution and health risk assessments. It illustrates that concentrations of Pb, Cd, and As in lakes and ex-mining ponds, and Mn, Cd and Pb in rivers exceed permissible limits for direct consumption. The levels of dissolved oxygen, TSS, and chemical oxygen demand (COD) are not within WHO and INWQS limits, pH of lakes and ex-mining ponds are lower than reference standards while that of rivers are high. Principal component analysis reveals that TSS, COD, BOD, Pb, and As are highly associated with ex-mining ponds. Cluster analysis shows similarity in pollution source between lake and ex-mining ponds. Risk assessment revealed that high chronic daily intake and metal index were beyond acceptable limit indicating high risk and exposure to toxic metals.

Nutraceutical industrial fenugreek seed spent (NIFGS), a relatively low-cost material abundantly available with little toxicity is used in crystal violet (CV) dye remediation from aqueous media and reported in the present study. To access the adsorption capacity, the factors affecting it are kinetics and the equilibrium thermodynamics. All the experiments were designed at approximately pH 7. The adsorption isotherm model proposed by Langmuir fits better than the Freundlich isotherm model. Kinetic studies data confirm the pseudo-second order model. It is evident from thermodynamic parameter values that the process of adsorption is endothermic, physical and dynamic. The process optimization of independent variables that influence adsorption was carried out using response surface methodology (RSM) through bi-level fractional factorial experimental design (FEED). The analysis of variance (ANOVA) was implemented to investigate the combined effect of parameters influencing adsorption. The possibilities of using dye-adsorbed NIFGS (“sludge”) for the fabrication of the composites using plastic waste are suggested.