Food chain environmental organic contaminants

Figure 1. Conceptual model illustrating examples of major anthropogenic contaminant sources and contaminants, their distribution within the abiotic environmental media, their movement into biota with potential food chain contamination, and potential effects at the organismal, population, conmiunity and ecosystem level of organization.

Sediments can also serve as potential exposure routes for aquatic food chains through the bioaccumulation of contaminants by benthic organisms. The potential of sediment contaminants to expose organisms in sediments and the water column is determined by their bioavailability. The bioavailability or bioaccessibility of nonpolar organic contaminants is determined by how strongly they are bound to organic matter in soil and sediment [31, 32]. This fact should be taken into account in a realistic assessment of the environmental risks of these contaminants (Fig. 13). 

Likelihood of chemical entering the food chain. The likelihood of an organic environmental contaminant, entering the food chain is determined by the availability of the chemical in the environment. This in turn is largely controlled by the rate of degradation of the chemical in the phase in which it is present. This factor must be assessed on the basis of observed data rather than by a theoretical approach. 

What are the effects of environmental change, both of climate and of pollutants and contaminants such as the introduction of persistent organic pollutants (POPs) into the food chain ... 

From a geochemical point of view, there are several options to investigate the present state and the development of, for example, the distribution and concentration of contaminants in the water column, suspended particulate matter, biota, and sedimentary deposits. Commonly, for most of the environmentally relevant substances (heavy metals, persistent organic pollutants, and nutrients) sediments are considered the final sinks following partly complicated pathways of transport, transformation, enrichment in the food chains, deposition, and burial. 

Fish are considered as sentinel organisms in the aquatic ecosystem to assess the environmental contamination of water by several compounds. Fish can be chronically exposed to different pollutants and can bioaccumulate by direct exposure or through the food chain. 

In addition to measurements on direct pathways to humans, consideration should be given to the measurement of activity concentrations in natural or artificially added indicator organisms or materials such as seaweeds, lichen or suspended particulate matter which are not always direct parts of food chains. Indicator materials are selected not because they represent a component of the human diet but because they concentrate radionuclides and provide a measure of trends in activity levels. Because of the concentration mechanism, radionuclides in indicator materials are usually more readily detectable than in foodstuffs, so the indicator organisms or materials provide a more sensitive indicator of environmental contamination [6]. 

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