Environmental Health: Nickel

Health Effects of Nickel

• Nickel and its comfounds are classified as Group 1 substances (carcinogenic to humans) by IARC, the International Agency for Research on Cancer.

 

•  Globally Harmonized System of Classification & Labeling of Chemicals

  H317 May cause an allergic skin reaction.

  H351 Suspected of causing cancer

  H372: Causes damage to organs (respiratory system, skin) through prolonged or repeated exposure

 

 

 

 

 

■  Environmental exposure

Nickel is a metal that exists naturally in the soil and is dispersed in the atmosphere through natural phenomena such as wind or volcanic eruptions. The amount of exposure to artificially generated nickel is greater than that of naturally occurring nickel, mainly during combustion of fossil fuels and in environments near industrial sites such as nickel smelters.

Humans are exposed to nickel through respiratory inhalation, ingestion, and dermal exposure. In the general public, ingestion of nickel-contaminated food is the main exposure route to nickel. Exposure to nickel can also occur through drinking water, and can occur through leaching from kitchen utensils or water pipes containing nickel. Smoking is also a major source of nickel exposure in the general population.

Nickel can also be absorbed through the skin, and you can be exposed to nickel through contact with nickel-containing products, such as jewelry.

 

■   Occupational exposure

Nickel is used in various industrial fields such as stainless steel manufacturing, alloy manufacturing, plating industry, nickel-cadmium battery manufacturing, metal paint, catalyst, and coin manufacturing. Stainless steel is used in a variety of applications such as kitchenware and pipes, and nickel alloys are also used in the aerospace industry and gas turbine manufacturing.

Nickel is also contained in welding rods used for welding stainless steel, and workers may be exposed to nickel in the form of fumes through the respiratory tract during welding work. Nickel plating is also widely used in plating work, and in this case, nickel is mixed in the mist of the plating solution and can be exposed through the respiratory tract. When painting using paint containing nickel, you may be exposed through the respiratory tract to nickel-containing paint dust.

Because nickel can be absorbed through the skin, exposure may occur when nickel in the form of dust, fume, or mist scattered in the air comes into contact with the skin.

 

■   Biological properties and mechanisms

Inhalation of nickel is the most important toxicological route. Inhaled nickel particles are deposited in the respiratory tract and, as with all inhaled particles, the site of deposition depends on particle size. Large particles (5-30 μm) are deposited in the nasopharyngeal region through collision, small particles (1-5 μm) enter the tracheal and bronchial regions by sedimentation, and particles less than 1 μm enter the alveolar space.

Approximately 25-35% of the inhaled nickel that remains in the lungs is absorbed into the blood. Depending on the compound, approximately 27% of a single oral dose of nickel in drinking water is absorbed, whereas only approximately 1% is absorbed when nickel is given with food.

After inhalation exposure, nickel is distributed to the lungs, skin, kidneys, liver, pituitary gland, and adrenal glands. Absorbed nickel is excreted in urine.

The carcinogenicity of nickel is believed to be due to the production of ionic nickel in target cells at key sites of carcinogenesis. Additionally, nickel compounds produce chromosomal abnormalities such as sister chromatid exchange, micronucleus formation in human lymphocytes, microsatellite mutations in human lung cancer cells, and mutations in kidney cells. Additionally, nickel can cause genetic damage, including DNA damage, cell deformation, and destruction of DNA repair, and generate ROS, which can attack DNA directly.

 

■    Health effects

• Acute effects

Acute exposure to high concentrations of nickel can cause skin and eye irritation and burns. Inhaling nickel can irritate the nose, throat, and lungs. Additionally, exposure to nickel can cause 'metal fever', which is accompanied by a metallic taste in the mouth, headache, fever and chills, pain, chest tightness, and coughing. Symptoms may be delayed for several hours after exposure and usually last for a day or two. Exposure to high levels of nickel can also cause headaches, dizziness, nausea and vomiting.

• Chronic effects

The IARC categorizes nickel and its compounds as carcinogens that have been definitively linked to the development of lung, nasal, and paranasal sinus cancer in humans.

Repeated inhalation of nickel can cause asthma symptoms such as coughing, shortness of breath, wheezing, and shortness of breath, as well as chronic bronchitis and decreased lung function.

Allergic contact dermatitis is the most common symptom of nickel exposure and is found in 10-20% of the general population. Allergic dermatitis can occur not only in daily life but also due to occupational exposure. Symptoms include itching and rash.

 

 

■    References

The content is primarily based on Casarett and Doull’s Toxicology 9th edition and the information on Nickel Compounds from EPA (https://www.epa.gov/sites/default/files/2016-09/documents/nickle-compounds.pdf).