Predicting the impacts of chemical pollutants on animal groups, a study published on the Trends in ecology & evolution, evaluates this interesting issue. The researchers said: "Chemical pollution is among the fastest-growing agents of global change.
Synthetic chemicals with diverse modes-of-action are being detected in the tissues of wildlife and pervade entire food webs. Although such pollutants can elicit a range of sublethal effects on individual organisms, research on how chemical pollutants affect animal groups is severely lacking.
Here we synthesise research from two related, but largely segregated fields - ecotoxicology and behavioral ecology - to examine pathways by which chemical contaminants could disrupt processes that govern the emergence, self-organisation, and collective function of animal groups.
Our review provides a roadmap for prioritizing the study of chemical pollutants within the context of sociality and highlights important methodological advances for future research." From chemical substances and/or mixtures present in the environment, often as a result of human activities, especially industrial and agricultural activities, potentially dangerous for human health and the environment.
Heavy metals, in the broadest sense, normally present in the environment in traces, such as mercury, cadmium and lead, become potentially dangerous if they reach certain concentrations. Cases of mercury poisoning have occurred around the world; the best known case is that which occurred in Japan in the fifties where the mercury discharged into the waters from a plastics plant entered the food chain, then into the fish and consequently passed on to the local population who lived basically from fishing.
Cadmium is mainly used in the manufacture of batteries and can pass into the environment causing kidney disease, bone marrow disease and pulmonary emphysema. Lead released into the atmosphere, formerly from automobile exhaust, for example, is absorbed by the body and can seriously damage the kidneys and lead to lead poisoning.
Among the most toxic polluting chemical substances we find dioxins, used in the production of herbicides. Dioxin pollution causes health problems for humans and animals, causes a considerable increase in prenatal deaths and births of children with serious malformations.
Infamous is the episode that occurred in Italy in 1976, in Seveso, where a toxic cloud containing dioxin was released from a reactor of a trichlorophenol production plant, causing serious inconvenience to man and the environment.