Used as contact insecticides; formerly widely used in agriculture and for domestic
purposes, their use is now restricted in some countries due to recognition of their
extreme persistence in the environment and potential for chronic toxicity.
Animals most affected
accidental ingestion (cattle, dogs) of agricultural products, treated cereals
and dressed seeds, and by licking out empty drums which previously contained
inhalation following crop spraying (spray or spray drift) in bad weather,
using either aerial or ground sprays in the vicinity of domestic or wild animals;
incorrect disposal of rinsing water from chemical containers or spray equipment
into rivers and ponds;
accidental disposal of wood preservatives (containing pentachlorophenols, and
frequently lindane) directly
into rivers or soakaways.
Note: possibility of iatrogenic incidents where some organochlorines (e.g. lindane)
are used on domestic pets for the treatment of ectoparasites.
Compounds in this category
AIdrin, chlordane, chlordecone, DDT, dicofol,
dieldrin, dienochlor, endosulfan, endrin, lindane, perthrane, toxaphene. Lindane
is also widely known as gamma hexachlorocyclohexane (gamma-HCH) or gamma benzene
Many of the above, along with organochlorine
compounds in general, are either banned from use (in both the UK and France) or are
permitted for only severely restricted usages.
Persistent liposoluble compounds which concentrate
in body fat and nervous tissue.
Toxic to the nervous system. For toxicity,
see entries for individual compounds.
Occasionally immediate onset of clinical signs with death occurring in a few minutes,
accompanied by hyperaesthesia, trembling, convulsions, or depression (particularly
following inhalation exposure). Characteristic clinical signs include:
muscular fasciculations of the face and neck followed by
tremor and shaking, generalized fasciculations;
occasionally agitation, aggression, abnormal postures or behaviour (wall butting,
autoausculation), groaning or whining, grinding of the teeth, nystagmus, superseded
tonic-clonic convulsions with periods of remission, paddling movements of the
legs, hyperaesthesia, opisthotonos and hyperthermia, which is common at this
Death may occur during the convulsive stage within a few hours, or after several
days. In particular species (e.g. cats), or in some individual animals, the dominant
features of poisoning are depression, weakness, prostration, coma and death.
(Difficult to diagnose and relatively nonspecific):
anorexia, weight loss, fall in milk production;
several episodes of trembling and shaking, persistent convulsions, deterioration,
death in several weeks to several months.
In acute poisoning
petechiae on the heart, intestines and lungs;
oedema of the brain and spinal cord.
In chronic poisoning
degeneration of the liver and kidneys is common.
No antidote. Symptomatic care only:
minimize dermal absorption (wash the
skin with soap) and limit absorption from the gut (adsorbents, gastric lavage);
control the convulsions: diazepam, xylazine;
use barbiturates with caution as they may depress cardiac and respiratory functions.
Organochlorines have two fundamental characteristics: liposolubility and chemical
persistence. In addition, they are powerful enzyme inducers. These factors explain
the extent and the degree of contamination of ecosystems by organochlorines, justifying
their restriction or even prohibition in use.
Organochiorines accumulate in the food chain, with highly significant concentration
factors of 10000 or more. Due to their ability to induce mono-oxygenase enzymes,
specific toxic effects can be observed which are clearly evident in animals at the
top of food chains. In raptors (birds of prey), eggshell fragility and lowered fecundity
have been well documented.
The inherent properties of the organochlorines also explain their transfer as residues
into fats used for foods, such as dairy products (milk, butter, etc.), which have
had important consequences for public health and a significant economic impact.