Question

In which side the chemical substance accumulate

Answer 1

his paper discusses problems connected with the unplanned effects upon man, his food-or resource-organisms and wildlife, of releasing naturally occurring and man-made chemical substances into the environment through human activities. The chief reason for studying this subject is the danger to human health, well-being and amenity which may be caused by unforeseen side-effects of a chemical substance during its production, transport, use and disposal. Potential harm to man is normally perceived and assessed by society on economic, social and cultural grounds. These provide the motivation for scientific research on the effects of chemical substances on the environment. Ideally, scientists should be able to predict likely effects of a chemical directly on man or indirectly via food, crops, livestock, wildlife or climate before the substance is released, enabling a more realistic cost-benefit appraisal to be made. A first approximation to predicting a potentially harmful substance may involve the following criteria: toxic in larger amounts; biologically non-essential; accumulating in tissue with age; environmentally persistent; biochemically active; not stored in inactive deposits in tissues much faster than ingested; more harmful to certain genotypes than others of the target species; environmentally mobile in the biogeochemical cycles; not forming highly stable inert compounds in nature; increasing in the environment during the last 100 generations of the target organism. A good deal is already known about the effects of chemical substances on man during their production, transport and use, from the study of occupational medicine, toxicology, pharmacology, etc., and to a lesser extent their effects on resource-organisms, from veterinary science and plant pathology. Much less is known about the effects of a chemical upon wildlife species, following its disposal in the environment. This last area of knowledge needs improving because ecological cycles and food chains may deliver the potentially hazardous chemical from affected wildlife back to man. Moreover, wildlife can often be used as indicators of environmental states and trends for a potentially harmful substance, giving an early warning of future risks to man. We are also frequently ignorant of how far wildlife may be supportive to human well-being: as a food-base for an important resource-species, e. g. fisheries or grazing animals; as a key species maintaining the stability of economically valuable ecosystems; as predators of crop or livestock pests; as a species involved in mineral recycling or biodegradation; as an important amenity. Failure to recognize the mutually interactive roles of man, resource-species, wildlife organisms and climate in the biosphere and their different tolerances to chemical substances has hindered the development of a unitary environmental management policy embracing all four biosphere components.