Reviews of Environmental Contamination and Toxicology Volume 242

Environmental pollution has increased many folds in recent years and in some places has reached levels that are toxic to living things. Among pollutant types, toxic heavy metals and metalloids are among the chemicals that pose the highest threat to biological systems (Jjemba 2004). Unlike organic pollutants, which are biodegradable, heavy metals are not degraded into less hazardous end products (Gupta et al. 2001). Low concentrations of some heavy metals are essential for life, but some of them like Hg, As, Pb and Cd are biologically non-essential and very toxic to living organisms. Even the essential metals may become toxic if they are present at a concentration above the permissible level (Puttaiah and Kiran 2008). For example, exposure to Zn and Fe oxides produce gastric disorder and vomiting, irritation of the skin and mucous membranes. Intake of Ni, Cr, Pb, Cd and Cu causes heart problems, leukemia and cancer, while Co and Mg can cause anemia and hypertension (Drasch et al. 2006). Similarly, various studies indicated that overexposure to heavy metals in air can cause cardiovascular disorders (Miller et al. 2007; Schwartz 2001), asthma (Wiwatanadate and Liwsrisakun 2011), bronchitis/emphysema (Pope 2000), and other respiratory diseases (Dominici et al. 2006).

Currently, nanotechnology revolutionizing both scientific and industrial community due to their applications in the fields of medicine, environmental protection, energy, and space exploration. Despite of the evident benefits of nanoparticles, there are still open questions about the influence of these nanoparticles on human health and environment. This is one of the critical issues that have to be addressed in the near future, before massive production of nanomaterials. Manufactured nanoparticles, which are finding ever-increasing applications in industry and consumer products fall into the category of emerging contaminants with ecological and toxicological effects on populations, communities and ecosystems. The existing experimental knowledge gave evidence that inhaled nanoparticles are less efficiently separated than larger particles by the macrophage clearance mechanisms and these nanoparticles are known to translocate through the lymphatic, circulatory and nervous systems to many tissues and organs, including the brain. In this review we highlight adverse impacts of nanoparticles on human and the environment with special emphasis on green nanoscience as a sustainable alternative.

Potato is one of the most important crops, after maize, rice and wheat. Its global production is about 300 million tons per year and is constantly increasing. It grows in temperate climate and is used as a source of starch, food, and in breeding industry.

Potato cultivation requires application of numerous agro-technical products, including pesticides, since it can be affected by insects, weeds, fungi, and viruses. In the European Union the most frequently used pesticides in potato cultivations check are: thiamethoxam, lambda-cyhalothrin and deltamethrin (insecticides), rimsulfuron (herbicide) and metalaxyl (fungicide).

Application of pesticides improves crop efficiency, however, as pesticides are not totally selective, it affects also non-target organisms. Moreover, the agrochemicals may accumulate in crops and, as a consequence, negatively influence the quality of food products and consumer health. Additional risks of plant protection products are related to their derivatives, that are created both in the environment (soil, water) and in plant organisms, since many of these compounds may exhibit toxic effects.

This article is devoted to the degradation processes of pesticides used in potato crop protection. Attention is also paid to the toxicity of both parent compounds and their degradation products for living organisms, including humans. Information about the level of pesticide contamination in the environment (water, soil) and accumulation level in edible plants complement the current knowledge about the risks associated with widespread use of thiamethoxam, lambda-cyhalothrin and deltamethrin, rimsulfuron and metalaxyl in potato cultivation.

Malaysia is a developing country in Southeast Asia, with rapid industrial and economic growth. Speedy population growth and aggressive consumerism in the past five decades have resulted in environmental pollution issues, including products containing polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). PCBs and PBDEs are classified as persistent organic pollutants (POPs) by the Stockholm Convention due to their persistence, bioaccumulation in the environment and toxicity to humans and wildlife. These compounds are known to cause liver dysfunction, thyroid toxicity, developmental neuro-toxicity and possibly cancer. PCBs in air, mussels, pellets, seawater, fresh water, and human breast milk samples were analyzed in Malaysia, while studies on the pollution level of PBDEs in Malaysia were conducted on mussels, soils, leachate and sediment samples. PCBs in breast milk collected from Malaysia was the highest among Asian developing countries, with mean concentration of 80 ng/g lipid weight. On the other hand, the mean concentration of PCBs in mussels collected from Malaysia recorded the second lowest, with 56 ng/g and 89 ng/g lipid weight in two studies respectively. The concentrations of PBDEs in mussels taken from Malaysia fall in the range of 0.84–16 ng/g lipid weight, which is considerably low compared to 104.5 ng/g lipid weight in Philippines and 90.59 ng/g in Korea. Nevertheless, there are limited studies on these compounds in Malaysia, particularly there is no research on PBDEs in breast milk and sediment samples. This review will summarize the contamination levels of PCBs and PBDEs in different samples collected from Asian countries since 1988 until 2010 with a focus on Malaysia and will provide needed information for further research in this field.

Increased use of nitrogenous (N) fertilizers in agriculture has significantly altered the global N-cycle because they release nitrogenous gases of environmental concerns. The emission of nitrous oxide (N₂O) contributes to the global greenhouse gas accumulation and the stratospheric ozone depletion. In addition, it causes nitrate leaching problem deteriorating ground water quality. The nitrate toxicity has been reported in a number of studies showing the health hazards like methemoglobinemia in infants and is a potent cause of cancer. Despite these evident negative environmental as well as health impacts, consumption of N fertilizer cannot be reduced in view of the food security for the teeming growing world population. Various agronomic and genetic modifications have been practiced to tackle this problem. Some agronomic techniques adopted include split application of N, use of slow-release fertilizers, nitrification inhibitors and encouraging the use of organic manure over chemical fertilizers. As a matter of fact, the use of chemical means to remediate nitrate from the environment is very difficult and costly. Particularly, removal of nitrate from water is difficult task because it is chemically non-reactive in dilute aqueous solutions. Hence, the use of biological means for nitrate remediation offers a promising strategy to minimize the ill effects of nitrates and nitrites. One of the important goals to reduce N-fertilizer application can be effectively achieved by choosing N-efficient genotypes. This will ensure the optimum uptake of applied N in a balanced manner and exploring the molecular mechanisms for their uptake as well as metabolism in assimilatory pathways. The objectives of this paper are to evaluate the interrelations which exist in the terrestrial ecosystems between the plant type and characteristics of nutrient uptake and analyze the global consumption and demand for fertilizer nitrogen in relation to cereal production, evaluate the various methods used to determine nitrogen use efficincy (NUE), determine NUE for the major cereals grown across large agroclimatic regions, determine the key factors that control NUE, and finally analyze various strategies available to improve the use efficiency of fertilizer nitrogen.