D.D.T. (DICHLORO-DIPHENYL-TRICHLO- ROETHANE OR CHLOROPHENOTHANE), ALDRIN, DIELDRIN, ENDRIN, HEXACHLORO- CYCLOHEXANE (GAMMEXANE, LINDANE, BENZENE HEXACHLORIDE), CHLORDANE, METHOXYCHLOR, TOXAPHENE.
These chlorinated hydrocarbons are used at home, in gardens and in agricultural fields as insecticidal agents. They are insoluble in water. D.D.T. is a volatile (slow of course) solid having a faint smell. It is highly soluble in benzene and chloroform, moderately soluble (11%) in kerosene, and slightly soluble (2%) in ethyl alcohol. Other chlorinated hydrocarbons are soluble in fat solvents including kerosene. Aldrin, dieldrin and chlordane are polycyclic, polychlorinated hydrocarbons. Methoxychlor is methoxy analogue of D.D.T. and lindane, ganunexane and benzene hexachloride are isomers of hexachloro- cyclohexane.
Mode of insecticidal use – Being insoluble in water, these are used either as dust or emulsion or mixed with solvents like kerosene.
Absorption, fate and excretion – For the insects, chlorinated hydrocarbons are contact poisons and are absorbed through the exoskeleton of the insects. In human being, except dieldrin, chlorinated hydrocarbons in dry powder form are only poorly absorbed through the mucus membrane of G.I. tract, and are not absorbed through the skin. Dieldrin and endrin, in dry powder form, are absorbed well through the skin and mucus membrane of the G.I. tract. Chlordane being liquid, is absorbed through the skin. When dissolved in kerosene and other solvents, all are rapidly absorbed, both through skin and mucus membrane. In the body, these are mainly deposited in the body fat and also to a small extent in liver, kidneys and brain. These are destroyed mainly in the liver. Some part of some metabolic products are excreted in stool, urine and milk.
Mode of action – These are stimulants of central nervous system and cause death by overstimulation. But these compounds are not always very toxic. Sometimes their solvents are more immediately toxic than them.
Fatal doses – For Aldrin, dieldrin and endrin – 2.5 gm.
For chlordane-5-7 gm.
For D.D.T. and lindane -15 – 30 gm.
For gammexane – No reliable estimated fatal dose is available. With gammexane fatality is not expected.
Fatal period – With optimum dose death occurs within some hours.
Signs and symptoms – With D.D.T. and gammexane, nausea, vomiting and diarrhoea occurs, possibly due to the action of their solvents. After an hour or two, absorption of the poison causes headache, dizziness and weakness. With higher dose cerebral disturbance like restlessness, irritability, dizziness, palpitation, tremor, twitching of muscles and convulsion occur: In children, death may occur within a few hours due to respiratory failure. After the immediate danger is over, risk of hepatitis, irritation of the gut with vomiting (often mixed with blood), melena, bile in urine and tachycardia may persist.
Gammexane causes more irritation but is less toxic than D.D.T.
Aldrin, dieldrin, endrin, chlordane, toxaphane are more active convulsants. With these, there are dizziness, nausea, headache, and ataxia. Convulsion comes suddenly. If convulsion or unconsciousness occur without any other preceding symptoms, then the prognosis is grave. Convulsions are like that of grandmal epilepsy with tonic and clonic phases followed by stupor.
Complications or delayed effects of these agents are gastro-intestinal irritation, hepatitis and renal damage.
In chronic poisoning with chlorinated hydrocarbon compounds, there are vague neurological symptoms and toxic rash in the skin.
1. Removal of the ingested poison by emesis or gastric lavage and magsulph purgation.
2. When poisoning is through surface contact – removal of clothings and washing of the skin.
3. If after first convulsion excitability persists in the form of hyperexcitation, exaggerated reflexes and muscular twitching, then pentobarbitone sodium, 180 mg, I.V. or paraldehyde, 4 – 6 ml I.M. is given.
4. If convulsion repeats, then controlled respiration is recommended with the help of an anaesthetist.
Prophylaxis – To prevent exposure and poisoning, precautionary steps as recommended for organophosphorus compounds are also recommended for chlorinated hydrocarbons.
Postmortem appearance –
Externally, there is cyanosis with other signs of asphyxial death, kerosene-like smell near the mouth, discharge of blood stained froth from the nose and mouth.
Internally, the stomach content smells like that of kerosene. There are signs of irritation of the stomach mucus membrane. Lungs are congested and oedematous with subpleural haemorrhagic spots. There is froth in the lumen of the respiratory tract. Organs are congested. There may be fatty degeneration of liver, kidneys and adrenal.
Medicolegal aspects –
Accidental poisoning occurs, more in case of children who has access to the poison. It is also because, tolerance for the poison is less in children. Accidental poisoning may also occur in persons who handle the poison. But fatality in this way in adults is not expected.
Suicidal poisoning is common, more in the rural sides.
Homicidal poisoning is very very rare. In homicidal poisoning, the smell of the poison is masked by administering it with alcohol.
Many of the signs and symptoms in poisoning cases may be due to the effects of the solvents like kerosene.