The term organochlorine refers to a wide range of chemicals that contain carbon, chlorine and, sometimes, several other elements. A range of organochlorine compounds have been produced including many herbicides, insecticides, fungicides as well as industrial chemicals such as polychlorinated biphenyls (PCBs). 
Organochlorine compounds are potential endocrine disrupting compounds, which means that they might interference with the endocrine systems of animals. Chemicals, which interfere with the endocrine system, disrupt the hormone balance of an animal. This typically results in disruption of the reproductive processes in aquatic organisms, or causes immunodeficiency. These effects can be caused by very low concentrations, considerably lower than the ones which are mutagenetic or acutely toxic.
Organochlorine compounds are lipophylic, meaning they are more soluble in fat than in water. This gives them a high tenancy to accumulate in the food chain (biomagnification). This because once taken up the compounds can persist in the animals for periods of months to decades. Therefore animals are likely to ingest more organochlorine compounds than they can excrete, allowing the compounds to bioaccumulate.
Because the organochlorines are stored in the fatty tissues of the body, they will only become biologically available (and have effects) when the fat tissues are metabolized. Animals may therefore have considerable body burdens of organochorines, but may only start showing effects in conditions of starvation, once the fat reserves are mobilized (see also here) 
Examples of organochorines
- OSPAR Commission 2000. Quality Status Report 2000, OSPAR Commission, London.
- Clark, R,B., 1999. Marine pollution. Oxford University press, Fourth edition, pp 161
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