Chlorinated hydrocarbon insecticides were introduced in the 1940s and 1950s. They comprise insecticides such as DDT, methoxychlor, chlordane, heptachlor, Aldrin, endrin, mirex, and lindane.
Organochlorines are known for their high determination and injurious characteristics. These pesticides result in neurological damage, endocrine disorders, and have several acute and chronic impacts on health. Hence contamination of the environment with organochlorine pesticides drastically affects the ecosystem.
Analysis of the National Health and Nutrition Examination Survey 1999–2004 studied the relation between organochlorine pesticides which revealed that serum concentrations of b-HCH and dieldrin were significantly associated with prostate cancer prevalence. A study conducted in China also revealed that prenatal exposure to DDT, β-BHC, HCB, and mirex caused a decrease in the birth weight of infants.
DDT is one of the common pesticides used which was manufactured in 1874. During World War II, the United States used a large amount of DDT to control vector-borne diseases, as typhus and malaria. After the war, the use of DDT turned out to be widespread in agriculture, public health, and households. However, it had several negative environmental impacts which ultimately led to the prohibition of DDT.
Classification of Organochlorine Pesticides
Organochlorine can be classified into three types:-
- Monocyclic:- The name suggests monocyclic which means having a single cycle. Its examples are Gammahexachlorocyclohexane (lindane) and Benzene Hexachloride (BHC).
- Dicyclic:- Organochlorines having two-cycle. Its examples are DDT and Methoxychlor.
- Polycyclic:- Organochlorines having multiple cycles. Its examples are Aldrin & Endrin.
Properties of Organochlorine Pesticides
- These compounds are available as dusting powders, emulsions, granules, or solutions.
- The chemical prototype of this group of pesticides is chlorophenothane, which is present in each member of the group.
- Organochlorides are volatile, stable, and highly persistent in the environment, which causes cumulative effects on the environment as well as human beings and other animals.
- They are non-polar with low aqueous solubility and high lipid solubility.
- These can be introduced into the environment through pesticide application to the crops, industrial discharge, wastewater discharge, etc.
Toxicokinetics
Organochloride compounds are absorbed through skin, inhalation, and the gastrointestinal tract. Most of the compounds are metabolized slowly in the body and remain in tissues, especially fatty tissues for a prolonged duration. These compounds are metabolized in the liver and are excreted in urine, feces, and milk.
Toxicodynamics
- Organochlorines affect nerve impulse transmission by altering membrane Na+ and K+ flux, resulting in Central Nervous System (CNS) hyperexcitability,
- Organochlorines produce myocardial irritability thus predisposing to cardiac arrhythmias,
- DDT and related compounds affect the sodium channel and sodium conductance across the neuronal membrane, especially of axons.
- Cyclodine and lindane appear to inhibit the GABA-mediated chloride channels in the CNS.
Mode of Action of Organochlorine Pesticides
All the Organochlorines can be absorbed orally, transdermally, and by inhalation. Gastrointestinal absorption of these means is generally efficient, particularly in the presence of absorbable lipid fat.
DDT is the least well-absorbed transdermally, while dieldrin is very well-absorbed. Many of these compounds are metabolized slowly and persist in tissues for prolonged periods. High residue levels from Organochlorine insecticide poisonings are found in adipose tissue. However, unlike other Organochlorine pesticides, methoxychlor does not substantially accumulate in the fatty tissues of humans.
Signs & Symptoms of Organochlorine Toxicity
CNS excitation and depression are the primary clinical effects of acute organochlorine toxicity. Therefore, patients may be present with any of the following:
- Initial euphoria with auditory or visual hallucinations and perceptual disturbances
- Seizures
- Agitation, lethargy, or unconsciousness
Other manifestations of chronic exposure are as follows:
- Anorexia
- Hepatotoxicity
- Renal toxicity
- CNS disturbances
- Skin irritation
Fatal Dose of Organochlorine Toxicity
The fatal dose is variable for different members of these pesticides.
- DDT– 15 to 30 gm
- Lindane– 15-30 gm
- Aldrin/Endrin/Dieldrin– 2 to 6 gm.
Fatal Period of Organochlorine Toxicity
The fatal period varies from half an hour to several hours
How Do Humans Come in Contact With Organochlorine?
People can be exposed to organochlorine pesticides through accidental inhalation exposure if they are in an area where they were recently applied. The chemicals can also be ingested in fish, dairy products, and other fatty foods that are contaminated.
Organochlorines can be measured in fat, blood, urine, semen, and breast milk. Samples of blood and urine are easy to obtain, and levels in these samples may help show low, moderate, or excessive exposure. However, the tests cannot show the exact amount of chemicals to which a person was exposed, or predict the chance of health effects in a person.
According to a paper named “Organochlorine pesticides, their toxic effects on living organisms and their fate in the environment“ published in National Centre for Biotechnology and Information by Ravindran J., Pankajshan M., and Puthur S., the organochlorine is responsible for hypertension, cardiovascular disorders, and other health-related problems in humans.
They act as endocrine disrupting chemicals (EDCs) by interfering with molecular circuitry and function of the endocrine system of farmworkers, their families and those who pass through a region applied with pesticides can absorb a measurable quantity of pesticides. Direct or indirect exposure to pesticides leads to neuromuscular disorders and stimulation of drug and steroid metabolism.
Organochlorine Pesticide Poisoning
Acute Poisoning
- Gastrointestinal Tract- Nausea, vomiting, diarrhea hyperaesthesia, or paresthesia of mouth and face
- CNS- headache, vertigo, myoclonus, mydriasis, weakness, agitation, confusion, convulsions, coma.
- Respiratory system- cough, wheezing, if aspiration or inhalation occurs,
- Renal failure,
- Hepatitis,
- Dermatitis.
Chronic Poisoning
Exposure to these compounds for a prolonged duration may result in cumulative toxicity characterized by anorexia, weight loss, weakness, tremors, opsoclonus, ataxia, pseudotumor cerebri, abnormal mental changes, oligospermia, thrombocytopenic purpura. Lindane and Benzene hexachloride has been linked to aplastic anemia.
Treatment in Cases of Organochlorine Poisoning
- Skin exposure- the affected part should be washed thoroughly with copious water.
- Ocular exposure- copious eye irrigation with normal saline or tap water.
- Ingestion- gastric lavage and administration of activated charcoal.
- Inhalation- Oxygen administration, ventilator assistance.
- Maintain vital parameters, hydration, and urine output.
- Convulsions should be controlled with the judicious use of diazepam or lorazepam.
- Hyperthermia should be managed in the usual way.
- Arrhythmias can be managed with lidocaine.
Postmortem Findings
- Froth with blood stains emanating from the mouth and nostrils is observed.
- Kerosene-like smell is noticed when the body is opened.
- Mucous membranes of the esophagus, stomach, and intestines are congested.
- The liver, kidney, and brain are congested.
- Pulmonary edema is observed with bulky lungs.
- Petechial hemorrhages on the lungs and heart are observed.
Conclusion
The use of pesticides to improve agriculture has not only affected the crop but also alters the food chain and the ecosystem. These chemicals not only affect the crop, animals, and birds in a specific area but also affects the ecosystem balance. Pesticides cause high mortality. Hence the use of chemical pesticides should be controlled and more use of bio-pesticides should be employed.
Many alternative methods include manual removal, application of heat, covering weeds with plastic, placing traps and lures, removing pest breeding sites, maintaining healthy soils that breed healthy and more resistant plants, cropping species that are naturally more resistant to pests, and supporting bio-control agents such as birds and other pest predators.
Consumer awareness should be brought up among people in concern with the long-term harm caused by pesticides.
Also Have a Look at:
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- How Toxic is New Poison: Cerbera Odollam?
- How Are Poisons Classified Based on Their Mode of Action?
Frequently Asked Questions
1. What Are The Types of Pesticides? Are All Pesticides Toxic?
The different types of pesticides include Insecticides, Herbicides, Fungicides, and Rodenticides. Yes, all pesticides are potentially toxic to humans and their poisoning can be either acute or chronic depending on the exposure and quantity of the substance.
2. Most Toxic Pesticide Currently Available in The Market?
The most toxic pesticide currently available in the market is Paraquat. It is a herbicide and is used for weed control. It is highly toxic and can cause severe health problems. Those problems include lung disease, Parkinson’s disease, and cancer. Moreover, it also remains in the soil for years after its use thus can cause damage to the ecosystem for a longer time.
3. Is It Bad To Touch Pesticides?
Pesticides are harmful chemicals used to kill insects and rodents. They are very effective in killing pests and can be equally harmful to humans as well, thus they need to be handled very carefully. On touching them, it may cause skin burns and irritation, and many other health-related issues.
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