Overview
Nickel is a hard, silvery white transition metal with atomic number 28 and is widely used in industrial applications because of its strength, corrosion resistance, and ability to form durable alloys. It has no essential role in human physiology, but trace exposure occurs through environmental, dietary, and occupational sources. Measurement of nickel in biological samples is mainly performed to assess toxic exposure rather than nutritional status. Urine nickel estimation is considered the preferred test for evaluating exposure, as it reflects recent absorption more reliably than serum levels. Its exposure is a common cause of allergic reactions and is also associated with systemic toxicity when exposure is significant or prolonged.
Symptoms
Its exposure can lead to a range of clinical manifestations depending on the route, duration, and intensity of exposure. The most common presentation is allergic contact dermatitis, characterized by itching, redness, and rash at the site of skin contact. Respiratory symptoms such as cough, wheezing, asthma, or pneumonitis may occur following inhalation of nickel compounds. Gastrointestinal symptoms, including nausea, vomiting, abdominal discomfort, and diarrhea, can be seen after ingestion. At higher or chronic exposure levels, neurological complaints, cardiovascular involvement, and renal toxicity may develop.
Causes
Elevated nickel levels result primarily from occupational exposure in industries such as mining, welding, electroplating, metal refining, and battery manufacturing. Environmental contamination, smoking, and use of nickel-containing prosthetic implants can also contribute. Dietary intake from nickel-rich foods, canned foods, or contaminated water may increase exposure in susceptible individuals. Nickel enters the body through inhalation, ingestion, or skin contact and may trigger immune-mediated reactions or direct tissue toxicity. Impaired renal function can further increase circulating or urinary nickel levels due to reduced clearance.
Risk Factors
Individuals at higher risk include industrial workers exposed to nickel-containing materials, smokers, and people with prolonged skin contact with nickel-containing jewelry or accessories. Patients with pre-existing respiratory disease, kidney impairment, or known nickel allergy are more susceptible to adverse effects. Environmental and occupational exposure without adequate protective measures increases risk. Laboratory interpretation may be influenced by contamination during sample collection, dietary variation, smoking status, and recent exposure rather than total body burden.
Prevention
Prevention of nickel toxicity focuses on minimizing exposure and early detection in at-risk individuals. Use of protective equipment, proper ventilation in occupational settings, and avoidance of prolonged skin contact with nickel-containing materials help reduce risk. Dietary restriction of nickel-rich foods may benefit individuals with nickel allergy. For accurate testing, samples should be collected using trace element-free containers to avoid contamination. Monitoring urine or serum nickel levels supports assessment of exposure and effectiveness of preventive or therapeutic measures, helping reduce the risk of allergic reactions, organ toxicity, and long-term complications associated with nickel exposure.
