Malathion is a widely used organophosphate insecticide. It is applied in agriculture to protect crops, in public health for mosquito control, and in residential pest management for home gardens and to treat head lice in humans. This compound is typically applied as a spray, often from aircraft over large land areas, particularly in agricultural regions.
How Malathion Affects the Body
Malathion’s harmful effects stem from its ability to disrupt the nervous system by inhibiting the enzyme acetylcholinesterase (AChE). This enzyme normally breaks down acetylcholine, a neurotransmitter that transmits signals between nerve cells and to muscles. When malathion, or its more potent metabolite malaoxon, inhibits AChE, acetylcholine accumulates, leading to continuous nerve stimulation.
This overstimulation can occur in the central and autonomic nervous systems. Humans can be exposed to malathion by inhaling its vapors, absorbing it through the skin, or ingesting it. While malathion itself has relatively low toxicity to mammals, its metabolite malaoxon is significantly more toxic.
Recognizing the Signs of Poisoning
Recognizing the signs of malathion poisoning is important for prompt action, as symptoms vary based on the level of exposure. The effects manifest across different physiological systems due to acetylcholine accumulation.
Muscarinic effects, which impact glands and smooth muscles, can include excessive salivation, lacrimation (tearing), urination, defecation, and vomiting. Individuals might also experience pinpoint pupils (miosis), increased sweating, and respiratory issues like bronchorrhea (excessive bronchial secretions) and bronchospasm, leading to difficulty breathing.
Nicotinic effects primarily involve skeletal muscles and can present as muscle twitching, fasciculations (small, involuntary muscle contractions), and generalized muscle weakness. In more severe cases, this weakness can progress to paralysis, particularly affecting respiratory muscles. Central nervous system effects are common and may include headaches, dizziness, confusion, restlessness, and agitation. Severe poisoning can lead to more serious neurological manifestations such as seizures, respiratory depression, or even coma.
Immediate Response and Medical Treatment
Immediate action is important in cases of suspected malathion poisoning. If exposure is through inhalation, move the affected individual to fresh air immediately. For skin exposure, remove all contaminated clothing and thoroughly wash the skin with soap and water for at least 15 minutes. If eyes are affected, rinse them with clean water for a similar duration.
After initial first aid, call emergency services, such as 911 or a local poison control center, without delay. Medical professionals will provide further treatment, which often includes administering medications like atropine and pralidoxime chloride (2-PAM). Atropine works by blocking the effects of excess acetylcholine at certain receptor sites, helping to dry up secretions and improve breathing. Pralidoxime helps to reactivate the acetylcholinesterase enzyme, reversing muscle paralysis, especially in respiratory muscles. These treatments are often administered in conjunction, with doses adjusted based on the patient’s response and the severity of poisoning.
Preventing Accidental Exposure
Preventing malathion poisoning involves careful handling and adherence to safety guidelines. All pesticide products, including those containing malathion, should be stored in their original containers, away from food, water sources, and out of reach of children and pets. Always read and follow label instructions before use, paying close attention to recommended application rates and safety precautions.
When handling malathion, wearing appropriate personal protective equipment (PPE) is advised. This typically includes gloves, protective clothing, and in some cases, respiratory protection like masks, to minimize skin absorption and inhalation. Ensuring adequate ventilation during application is important to disperse fumes. After handling malathion or any pesticide, thoroughly washing hands with soap and water is a simple yet effective step to prevent accidental ingestion. When spraying occurs outdoors, remain indoors, close windows, and cover outdoor items like garden vegetables and pet dishes to reduce exposure.