chronic bronchitis, reduced lung function, and cancer of the lung and nasal sinus, have occurred in people who have
breathed dust containing nickel compounds

1.5 How can nickel affect my health?

Laws today protect the welfare of research animals, and scientists must comply with strict animal care guidelines

The most common harmful health effect of nickel in humans is an allergic reaction to nickel. Approximately 10-15% of
the population is sensitive to nickel. A person can become sensitive to nickel when jewelry or other things containing
nickel are in direct contact with the skin. Wearing earrings containing nickel in pierced ears may also sensitize a person
to nickel. Once a person is sensitized to nickel, further contact with the metal will produce a reaction. The most common
reaction is a skin rash at the site of contact. In some sensitized people, dermatitis (a type of skin rash) may develop in
an area of the skin that is away from the site of contact. For example, hand eczema (another type of skin rash) is fairly
common among people sensitized to nickel. Less frequently, some people who are sensitive to nickel have asthma
attacks following exposure to nickel. People who are sensitive to nickel have reactions when nickel comes into contact
with the skin. Some sensitized individuals react when they eat nickel in food or water or breathe dust containing nickel.
More women are sensitive to nickel than men. This difference between men and women is thought to be a result of
greater exposure of women to nickel through jewelry and other metal items.

People who are not sensitive to nickel must eat very large amounts of nickel to suffer harmful health effects. Workers
who accidentally drank light-green water containing 250 ppm of nickel from a contaminated drinking fountain had
stomach aches and suffered adverse effects in their blood (increased red blood cells) and kidneys (increased protein in
the urine). This concentration of nickel is more than 100,000 times greater than the amount usually found in drinking

The most serious harmful health effects from exposure to nickel, such as chronic bronchitis, reduced lung function, and
cancer of the lung and nasal sinus, have occurred in people who have breathed dust containing nickel compounds while
working in nickel refineries or nickel-processing plants. The levels of nickel in these workplaces were much higher than
usual (background) levels in the environment. Lung and nasal sinus cancers occurred in workers who were exposed to
more than 10 mg nickel/m³ as nickel compounds that were hard to dissolve (such as nickel subsulfide). Exposure to high
levels of nickel compounds that dissolve easily in water (soluble) may also result in cancer when nickel compounds that
are hard to dissolve (less soluble) are present, or when other chemicals that can cause cancer are present. The
concentrations of soluble and less-soluble nickel compounds that were found to have caused cancers were 100,000 to
1 million times greater than the usual level of nickel in the air in the United States. The U.S. Department of Health and
Human Services (DHHS) has determined that nickel metal may reasonably be anticipated to be a carcinogen and nickel
compounds are known human carcinogens. The International Agency for Research on Cancer (IARC) has determined
that some nickel compounds are carcinogenic to humans and that metallic nickel may possibly be carcinogenic to
humans. The EPA has determined that nickel refinery dust and nickel subsulfide are human carcinogens.
Lung inflammation and damage to the nasal cavity have been observed in animals exposed to nickel compounds. At
high concentrations, the lung damage is severe enough to affect lung function. Long-term exposure to lower levels of a
nickel compound that dissolves easily in water did not cause cancer in animals. Lung cancer developed in rats exposed
for a long time to nickel compounds that do not dissolve easily in water.

Oral exposure of humans to high levels of soluble nickel compounds through the environment is extremely unlikely.
Because humans have only rarely been exposed to high levels of nickel in water or food, much of our knowledge of the
harmful effects of nickel is based on animal studies. Eating or drinking levels of nickel much greater than the levels
normally found in food and water have been reported to cause lung disease in dogs and rats and to affect the stomach,
blood, liver, kidneys, and immune system in rats and mice, as well as their reproduction and development