Arsenic Poisoning

Arsenic Poisoning Definition

The condition is marked by increase in the levels of an element in the body called arsenic. Prolonged exposure to the poisonous chemical is highly detrimental to health and may produce serious repercussions.

Arsenic Poisoning History

Arsenic was used as a therapeutic agent in China to treat various diseases like syphilis. Many artists and craftsmen were severely affected due to excessive exposure to the chemical substance. In the middle ages, it was also used as a lethal weapon against the enemies. Bangladesh reported the maximum number of cases of poisoning in 1983. World Health Organization discovered well water as the source of arsenic, and called this incident as the “largest mass poisoning of a population in history” and a public health emergency.

Arsenic Poisoning Types

Based on the severity and onset of symptoms, the condition can be classified into the following types:

Chronic Arsenic Poisoning

In this type, the effects of lower levels of toxin can be long-lasting or persistent and could manifest into nearly fatal complications.

Acute Arsenic Poisoning

Short-term exposure of arsenic at or above the toxic level can cause the disease to last for a brief period of time with immediate arrival of the symptoms.

In exceptional cases, some individuals are deliberately exposed to the chemical substance, a condition better known as “intentional arsenic poisoning”.

Signs and Symptoms of Arsenic Poisoning

Presence of excessive arsenic in the body is a sign of a dreadful disorder that can give rise to a host of life-threatening conditions.

Acute Arsenic Poisoning

The symptoms normally begin within 30 minutes to 2 hours and may involve the following:

• Severe abdominal pain and cramps
• Diarrhea
• Dehydration
• Vomiting
• Smell of garlic in breath and body
• Excessive production of sweat
• Abnormal breakdown of red blood cells, resulting in anemia
• Vertigo
• Sudden severe confusion
• Seizures and shock
• Circulatory collapse
• Oral burns
• Gastrointestinal bleeding
• Cardiac changes
• Gangrene of limbs
• Breathlessness, due to acute respiratory distress syndrome
• Pulmonary swelling and irritation
• Muscle cramps
• Hair loss
• Chills
• Dark or blood-laden urine
• Death

Chronic Arsenic Poisoning

Constant build-up of the poisonous chemical in the body can lead to gradual deterioration of multiple organs. Some of the clinical presentations of the chronic condition are:

• Hyperpigmentation or discoloration of the skin
• Extreme swelling, thickening and reddening of the outer layer of the skin
• Lines of discoloration across the nails of the fingers
• Loss of sensory and motor functions
• Renal, pulmonary and hepatic failure
• Hypertension
• Metallic taste in mouth
• Muscle dystrophy
• Lack of muscle coordination

Arsenic Poisoning Causes

Arsenic is a metalloid, a mixture of metals and non-metals, which can readily combine with organic and inorganic materials and cause toxicity. Presence of the grey-appearing, heavy, chemical element in greater amounts in living tissues can cause functional erosion of the cells. Arsenic and its compounds are capable enough to react with proteins and paralyze most of the cellular functions. The metalloid can exist in either of the following forms:

Inorganic arsenic

It is available as a gaseous agent called arsine gas and forms colorless, odorless, crystalline oxides, soluble in water. In a similar fashion, the inorganic metalloid binds with chlorine and sulfur to form several compounds.

Organic arsenic

It is a chemically designed compound in which arsenic is made to combine with any carbon-containing compounds. Although not a lethal toxin at lower levels, organic arsenic can be moderately dangerous at higher concentrations.

The entry of arsenic into the body occurs when an individual unknowingly consumes or inhales it. Once the metallic agent reaches or crosses the toxic level, the condition becomes acute and results in rapid onset of the symptoms. The chief sources of the lethal element are:

• Contaminated drinking water
• Pesticides/Herbicides/Fungicides
• Paints
• Tobacco
• Burning of fossil fuels
• Few rice products
• Illegal distilled spirits
• Fruits and vegetables
• Seafood
• Poultry
• Copper and lead ore deposits

The condition is rampant among individuals working in industries like:

• Coal power plants
• Smelting
• Mining
• Pesticide plants
• Microelectronics
• Glass production and manufacturing
• Fireworks
• Wood preservation
• Nonferrous metal alloys

The various products manufactured by these industries are the potential sources of arsenic and its compounds. Occupational exposure is one of the most detrimental routes through which chronic poisoning occurs. It may equally affect people residing near such industrial places.

Arsenic Poisoning Pathophysiology

The cellular function gets largely affected when arsenic acts as an allosteric inhibitor by deactivating pyruvate dehydrogenase (PDH) complex, a trimeric enzyme that converts pyruvate into acetyl-CoA with the aid of NAD⁺. Once the enzyme gets completely inhibited, the energy system of the cell fails and causes apoptosis, the regulated process of programmed cell death. Utilization of thiamine, a water-soluble vitamin, is inhibited by the poisonous metalloid, resulting in its deficiency in the body.

Picture 1 – Arsenic Poisoning

Lactic acidosis, a condition marked by low pH in tissues and blood, occurs when arsenic aberrantly elevates the lactate levels. Potassium crucial for heart function and smooth muscle contraction gets lowered in the presence of arsenic trioxide. The most debilitating aspect of arsenic is the fact that it encourages the production hydrogen peroxide, which reacts with metals like manganese and iron to release hydroxyl radicals. The end product is the neutral form of the hydroxide ion that can damage a wide variety of macromolecules, including carbohydrates and amino acids. The trioxide form of inorganic arsenic typically present in ground water can severely impair the voltage-gated potassium channels, the transmembrane signaling proteins responsible for cellular electrolytic function. Chronic exposure of the toxic element results in high oxidative stress that disrupts the working of the cardiovascular system.

Arsenic poisoning in dogs

Consumption of rat or mouse trap bait is one of the most common causes of the metalloid poisoning in dogs. Affected animals may experience symptoms like staggering, vomiting, passing of blood-laden feces, and extreme exhaustion.

Arsenic Poisoning Diagnosis

Toxic poisoning is easily noticeable in this condition as the lethal symptoms do not take much time to appear. On the other hand, the chronic condition is marked by slow poisoning, especially in the case of contaminated water consumption, or occupational exposure. Physical examination of the skin and nails can provide the doctors with some clues that are directly related to the toxic condition. If something suspicious is observed in patients, doctors may order the following tests and exams:

Urine test

The organic compounds of arsenic are normally discharged in urine. In case of an acute exposure, the urine sample must be tested within 24-48 hours for accuracy. Examiners may find the characteristic garlic odor in the collected sample. Increased levels of inorganic arsenic can raise the toxicity of the condition.

Hematology test

The blood sample of an affected patient may reveal the following features:

• Elevated levels of arsenic within a few hours after the exposure
• Fragments of red blood cells
• Acid-base imbalance
• Increased amounts of calcium
• Decreased levels of potassium

Breath test

It is a simple diagnostic test used to detect the presence of garlic smell in the exhaled air.

X-ray

Radiography of the chest, abdomen, liver and kidneys may aid in identifying the defects caused by arsenic.

Electrocardiography (ECG)

This imaging procedure is highly reliable in detecting the abnormal rhythms of the heart, caused due to potassium imbalance.

Hair sample test

Traces of arsenic or its compounds often enter the hair from the blood. Analysis of a single hair strand not only reveals the presence of the metalloid but also helps determine the time of exposure.

Nerve conduction study

In this procedure, surface patch electrodes electrically stimulate and simultaneously record the time taken by the nerves to transmit electrical signals to the muscle. Low value of electrical conductivity indicates arsenic-induced sensory-motor peripheral neuropathy.

Arsenic Poisoning Treatment

Acute exposure of inorganic arsenic or arsine gas can be extremely fatal and result in death in the absence of spontaneous remedial actions. In such a critical situation, the patient must be immediately removed from the source of arsenic and the contaminated clothes must then be removed. In case the skin gets contaminated, it should be rinsed with adequate amount of water. Patients should immediately contact a physician, who may opt for any of the following treatment methods:

Chelation therapy

It involves the use of antidotes like dimercaprol and dimercaptosuccinic acid that removes arsenic from the blood proteins, and prevents destruction of red blood cells. However, these chelating agents may give rise to high blood pressure.

Dietary supplements

Potassium supplements must be given to patients to reduce the risk of a cardiac failure due to the formation of arsenic trioxide in the blood. Dosage is however, based on the health condition of patients and their response to therapy.

Nutritional treatment

A diet rich in garlic can combat the toxic effects of arsenic. The sulfur-containing elements in garlic and its extracts can readily bind to arsenic present in the tissues as well as blood, and discharges the metalloid in the urine.

Arsenic Poisoning Prognosis

Survivors of acute toxic exposure have a higher chance of developing peripheral nerve damage, cardiac disorders or renal problems. The prognosis for this condition usually ranges from fair to poor. However, the situation is far better in the case of chronic poisoning.

Arsenic Poisoning Complications

Consumption or inhalation of large amounts of arsenic can be extremely fatal. Long-term exposure to the metalloid has been associated with the following conditions:

• Diabetes
• Night blindness
• Jaundice
• Cancer
• Hepatic or digestive disorders

Arsenic poisoning is a highly lethal condition that needs timely treatment. Arsenic-free drinking water and a diet filled with micronutrients as well as antioxidants can prevent the aggravation of the condition.

References:

http://en.wikipedia.org/wiki/Arsenic_poisoning

http://www.bbc.co.uk/health/physical_health/conditions/arsenic_poisoning.shtml

http://www.medicalnewstoday.com/articles/241860.php

http://www.medicinenet.com/arsenic_poisoning/article.htm