Fisheries
6. What contaminants are affecting fisheries?
- 6.1 What contaminants can find their way into fish and seafood?
- 6.2 What are the risks associated with these contaminants?
- 6.3 How can fish safety be controlled?
6.1 What contaminants can find their way into fish and seafood?
See GreenFacts digest on Arsenic (metal)
See GreenFacts digest on Mercury (metal)
See GreenFacts digest on Dioxins (POP)
Several organic and inorganic compounds can find their way into fish and seafood. These compounds can be divided into three major groups:
- Metals and metal-like elements such as arsenic, cadmium, lead, mercury, selenium, copper, zinc, and iron, in either organic or inorganic compounds.
- Persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs), dioxins, and some insecticides. These substances tend to accumulate and persist in the environment.
- Processing-related compounds such as sulphites (used in shrimp processing), polyphosphates, nitrosamines, and residues of drugs used in aquaculture (e.g., antibiotics and hormones).
Many elements are essential for life at low concentrations but become toxic at high concentrations. Other elements such as mercury, cadmium, and lead are not essential for living organisms and are toxic even at low concentrations when ingested over a long period. Metals are released into the aquatic environment by both natural phenomena and human activities. In contrast, most organic pollutants that can affect fisheries are released by human activities.
Chemical substances may build up in body tissues over the life span of an individual (bioaccumulation). They can also build up along the food chain (biomagnification), leading to higher concentrations in predatory species. The presence of chemical contaminants in seafood is highly dependent on location, species, age, and feeding pattern, as well as the (lipid) solubility of the chemicals, and their persistence in the environment. More...
6.2 What are the risks associated with these contaminants?
Several studies indicate that in the open seas, which are still almost unaffected by pollution, most fish carry only the natural burden of metal-like inorganic substances.
In heavily polluted areas, however, contaminants can be found at higher concentrations. In fish intended for human consumption, levels of these chemicals are low and believed to be below levels likely to affect human health. Nevertheless, they can be of potential concern for people who consume larger amounts of fish and for especially sensitive groups, such as pregnant and nursing women and young children.
While scientists and other experts recognize that certain of these substances are present naturally in fish and seafood, some consumers regard their presence even at minimal levels as a hazard to health. Consequently, food scares can be easily started and further amplified if communication is mismanaged. A number of such scares concerning fish contaminants have recently led to significant negative impacts on fish trade flows.
6.3 How can fish safety be controlled?
Globalization and further liberalization of the world fish trade give rise to many benefits and opportunities but also to new safety and quality challenges.
In establishing maximum levels of pollutants in fish, regulators need to
- ensure the highest level of consumer health protection, but also
- take into account that fish are exposed to background contamination of the environment.
Setting levels that are too stringent could exclude too much fish from the market and thus endanger food supply. Strategies to reduce the background contamination of the environment must be adopted. In addition, consumer information and awareness programmes will be necessary in order to improve transparency and consumer education.
Progress in this area will require enhanced international cooperation in promoting mechanisms that are based on scientific principles, for instance through the WTO and the CAC. More...
