Assessment of ecologic and human health risks from a contaminated estuarine environment

Due to their particular geographic characteristics, estuaries are often used for diverse human and industrial activities that may generate and release potentially harmful chemical contaminants. Thus, estuaries may be reservoirs of a wide variety of chemicals, including mutagenic and carcinogenic ones (e.g., metals, polycyclic aromatic hydrocarbons and pesticides), particularly when considering the potential for aquatic sediments to accumulate and continuously re-suspend contaminants into the water column. Importantly, besides being available to the local biota, the proximity/use of these contaminated sites might also be unsafe to the local population, provided that they are directly exposed (e.g. fishing, agricultural or recreational activities) or indirectly, through their diet. This work was focused on the river Sado Estuary, where the northern banks include urban areas and a heavy-industry park while the southern banks are mainly impacted by extensive agriculture activities. Sizable amounts of hazardous contaminants (e.g., metals, pesticides and polycyclic aromatic hydrocarbons) were identified in the estuarine sediments raising concern to the local populations because estuarine organisms and locally produced vegetables constitute the basis of their diet. The study intended to assess the adverse effects of estuary contaminants on human and ecosystem health through an integrative methodology based on several lines of evidence. An epidemiological survey was conducted to assess the exposure of a local population to the estuary environment as well as their health status. Furthermore, analyses of sediments, soil and wells water contamination were performed. Biological effects were assessed in major estuarine species with commercial value (clams, sole and cuttlefish); the cytotoxic and genotoxic potential of sediments were characterized in a human cell line. The results showed that the sediments’ contaminants were capable of inducing concentration-dependent cytotoxic and genotoxic damage in vitro and also allowed the distinction between two ecogeographical areas (urban/industrial and rural) with respect to type and intensity of the genetic damage, likely reflecting different patterns of toxicants mixtures. The integration of data from all study components indicated that the estuary is moderately impacted by complex mixtures of toxicants, affecting the aquatic biota and potentially able of inducing adverse effects on human cells. Although no clear evidence of contaminant-related adverse health effects in the studied population was found, the dose-related genotoxicity observed in the in vitro approach together with the evidences of direct and indirect human exposure indicates that those toxicants might constitute a risk factor to the development of chronic-degenerative diseases.FCT-PTDC/SAU PTDC/SAU-ESA/100107/2008N/