Zinc Toxicity: Causes, Signs, Diagnosis & Treatment

Introduction:

Zinc metal is an essential mineral in the body that is responsible for the production of many enzymes. It is needed in the body in small amounts to perform the system's proper functioning; therefore, the dose estimation for adults is usually 15 mg daily. However, if zinc consumption exceeds the recommended levels, it can cause toxicity or poisoning in the body. Zinc toxicity can be caused accidentally, especially in children, or intentionally overdose, leading to severe poisoning and health problems in a person. Zinc toxicity can be life-threatening, and thus immediate medical attention must be availed to avoid fatal consequences.

What Are the Sources of Zinc Exposure?

• Occupational sources cause exposure to zinc via inhalation.

• Misuse or overuse of dietary supplements for zinc.

• Overuse of zinc-containing denture creams.

• Food sources are rich in zinc, like whole grains, meat, and poultry.

What Are the Causes of Zinc Toxicity?

Zinc toxicity can be caused due to various reasons.

These include:

• The dermal, respiratory, parenteral, and gastrointestinal routes can cause zinc toxicity.

• Occupational exposures through metal soldering, welding, and alloy production can cause flu-like symptoms due to zinc exposure at high levels.

• Respiratory distress syndrome, airway irritation, and chest pain can occur due to inhalation of zinc chloride in smoke bombs.

• Nutritional supplements also contain zinc and cause zinc toxicity through ingestion.

• Denture creams also contain zinc, and over-application of the cream can lead to an overdose of zinc in the body.

• Sunscreen, makeup products, and ointments also contain zinc and thus can cause toxicity via the dermal route.

What Are the Signs and Symptoms of Zinc Toxicity?

Zinc toxicity can be acute or chronic, causing the following symptoms :

Acute Zinc Toxicity: This occurs due to excessive intake or ingestion and inhalation of zinc at once. The symptoms produced are:

• Vomiting.

• Nausea.

• Diarrhea.

• Abdominal cramps.

• Appetite loss.

• Profuse sweating.

• Fatigue.

• Fever.

• Weakness.

• Muscle pain.

• Shortness of breath.

• Breathlessness or rapid breathing.

Chronic Zinc Toxicity: This occurs due to the regular intake of high zinc doses daily for a prolonged period. The symptoms produced are:

• Urinary dysfunction.

• Copper deficiency is due to zinc toxicity's interference with copper absorption.

• Good cholesterol or a low level of high-density lipoprotein is produced in the body.

• It decreases the white blood cells in the body and affects the immune system.

• Red blood cells become smaller in size and affect iron functioning and cause anemia.

What Is the Pathophysiology of Zinc Toxicity?

The zinc toxicity pathophysiology mainly depends upon the amount of intake and the route of zinc exposure. Acute toxicity of zinc is usually caused by zinc chloride and zinc sulfide ingestion, causing gastrointestinal signs and symptoms due to caustic effects. It also leads to renal injury, acute tubular necrosis, liver necrosis, coagulopathy, or thrombocytopenia.

In addition, inhalation of zinc fumes can cause damage to the respiratory canal. The pathophysiology of zinc toxicity is usually associated with flu-like symptoms produced due to inflammatory immune responses caused by zinc. However, chronic zinc exposure can lead to granulocytopenia, sideroblastic anemia, or copper deficiency. The actual cause of toxicity is unknown to some extent.

Why Is Zinc an Essential Mineral for the Body?

Zinc is an essential mineral for the body in many ways, such as:

• It helps in the production of various enzymes in the body and also carries out important chemical reactions.

• Zinc also plays an important role in cell growth division, reproduction, and energy supply to the body by breaking down carbohydrates in the body.

• Zinc is also needed for DNA synthesis and the growth of cells.

• It is also helpful in taste perception. An excessive amount of zinc can cause a metallic taste in the oral cavity.

• Zinc improves body immunity, helps heal damaged tissues, and helps build protein.

• Zinc also helps in vitamin A metabolism and olfactory and gustatory functions.

• It is also an essential mineral during fetal growth and development.

• Zinc is needed to treat copper deficiency in the body.

How Is Zinc Toxicity Diagnosed?

Diagnosis for zinc toxicity includes:

• Chest X-rays during zinc fume inhalation.

• Blood and urine tests analyze copper and zinc levels in the body.

• Liver functioning tests.

• Platelet count test.

• Kidney functioning tests, especially creatinine.

• CT (computed tomography) and ECG (electrocardiogram) scan.

How Is Zinc Toxicity Treated?

Zinc toxicity can be treated in the following ways:

• There is no antidote for zinc poisoning. Therefore, the toxicity can be treated with supportive treatment and removing the toxic source.

• Airway obstruction is rectified with oxygen therapy, intubation, or mechanical ventilation to provide initial support during zinc toxicity treatment.

• Antiemetic drugs and IV fluids can be given.

• H2 blockers and proton pump inhibitors can also reduce the digestion of zinc and stomach acids.

• Whole bowel irrigation can also reduce the gut burden due to zinc toxicity.

• Chelation medication like calcium disodium edetate binds zinc and reduces toxicity levels in the body.

• If zinc toxicity occurs due to inhalation, oral hydration and antipyretic drugs are used for supportive treatment.

• Supportive oxygen therapy and bronchodilators are given to a person in case of respiratory dysfunction and breathing difficulties.

• Chronic zinc toxicity is treated with chelation and copper sulfate.

What Are the Blood Disorders Caused by Zinc-Induced Copper Deficiency?

• Neutropenia- Disruption in the formation of white blood cells.

• Sideroblastic Anemia- Iron is not metabolized properly and causes a lack of red blood cells.

• Iron-Deficiency Anemia- Iron insufficiency in the body causes a lack of red blood cells.

What Is the Differential Diagnosis for Zinc Toxicity?

• Heavy metal toxicity (arsenic, lead, mercury, or titanium)

• Kidney injury.

• Pancreatic failure.

• Liver failure.

• Gastrointestinal bleed.

• Septic shock.

• Hemodynamic instability.

What Are the Complications Due to Zinc Toxicity?

Zinc toxicity-related complications include:

• Dehydration.

• Neuropathy.

• Prostate cancer.

• Recurrent airway obstruction.

• Polyneuropathy due to copper deficiency.

• Bone marrow effects ( affects white blood cells, red blood cells, and platelet production)

• Anemia.

Conclusion:

Zinc toxicity can occur due to exposure to various zinc sources, such as food diet, industrial products like dyes and paints, and zinc supplements. Zinc is essential as long as taken in the recommended dosage and can cause toxicity if over-consumed.

Zinc plays an important role in body functioning and thus must be consumed healthily to boost body immunity and functions. In case of overdose, immediate medical intervention is needed to overcome the toxic effects that can be fatal if not treated on time. Therefore, prevention must be taken to avoid a person's overconsumption of the mineral intentionally or accidentally.