Biomarkers of Environmental Pollutants

Thousands of pollutants enter daily into environment and exert various kinds of stress on organisms and ecosystems. Risk assessment of these pollutants to organisms and ecosystems is challenging because of diversities in chemical nature and mode of toxicity of the pollutants as well as variation in sensitivities of the organisms exposed to the pollutants. Even low, relatively innocuous concentrations of pollutants often produce deleterious effects on organisms, which are difficult to be predicted, because measurable effects are expressed only after prolonged exposure. But it may be too late to take remedial actions or steps to reduce risk when these incipient effects are expressed. Therefore, it is necessary to develop early warning signals or biomarkers that convincingly reflect adverse biological responses towards anthropogenic environmental toxins even atminute concentrations [1]. A biomarker is defined as “a change in biological response, ranging from molecular through cellular and physiological responses to behavioral changes, which can be related to exposure to or toxic effects of environmental chemicals” [2]. Recent developments in molecular biology and biotechnology and inventions of sophisticated instruments have led to the development of novel, more sensitive validated biomarkers of exposure, effect, and susceptibility to the adverse effects of terrestrial and aquatic pollutants [3]. Validity of these biomarkers has been tested in several laboratory and field studies [1]. In addition, systematic use of multiple biomarkers has been found asmost useful in the assessment of pollutants’ effects [4]. This special issue on biomarkers of environmental pollutants contains ten papers, which discussed some recent applications of biomarkers in terrestrial and aquatic environment. A few papers deal with a single sensitive biomarker, while others deal with combinations of selected biomarkers. The papers have been categorized under three main groups.