| Toxicity: |
Occupational exposures
may occur in its mining, smelting, and refining. The general
population ingests nickel in food. Skin sensitization and
dermatitis leading to chronic eczema, called “nickel itch,”
frequently occurs, especially in wearers of pierced earrings.
Nickel can also irritate the conjunctiva and respiratory tract
mucous membranes. Absorption from the digestive tract is
poor, so systemic poisoning is rare, but since it is an irritant
it acts as an emetic. Systemic effects include hyperglycemia,
capillary damage, CNS depression, myocardial weakness, and
kidney damage. Nickel and its compounds are carcinogenic
following inhalation, but not following ingestion or skin contact. Cancer of the lung and nasal passages results, with a
latent period of about 25 years; smokers are at greater risk.
In addition to irritation and carcinogenesis, nickel carbonyl
(nickel tetracarbonyl, Ni(CO)4) exerts relatively mild, tran_x0002_sientinitial symptoms including headache, giddiness, nausea,
and shortness of breath. These symptoms are followed by
very serious symptoms hours to days later, consisting of tightness in the chest, shortness of breath, rapid respiration, pulmonary edema, cyanosis, and extreme weakness; this can be
fatal. Heat decomposition of nickel carbonyl yields carbon
monoxide. Chelating agents can be used to remove nickel
from the body. |