Lead is a dense, soft, grey metal with a low melting point (327oC). It is the most familiar of the metallic elements. No one can claim to have discovered lead or to have been the first to isolate it. It can be traced back to the prehistoric times. The Bible mentions applications of lead in one of the oldest books, the Book of Job.

Lead is found in many regions of Canada, including the Northwest Territories, British Columbia, The Yukon, Manitoba, Northern Ontario, New Brunswick and Cape Breton Island. The Sullivan Mine at Kimberly, B.C. is one of the world's largest producers of lead-zinc ore. A typical ore contains sulphides of lead, galena, zinc and iron, as well as small quantities of other metals.

Lead has an extensive variety of oxides and compounds, many of which are of commercially importance.

Other uses of lead include:

As much as lead is useful, it is also a poison. Metallic lead can be absorbed through the skin because it reacts with the weak acids in perspiration and dissolves. Cases of lead poisoning have resulted from the repeated handling of lead foil, bullets, and other lead objects.

Lead ions are present in some foods, beverages, public water supplies (from lead pipes), and even air (from lead compounds in automobile exhausts). The body must be able to rid itself of lead, otherwise everyone would have died long ago of lead poisoning. The average person can excrete about 230 microgram of lead a day through the kidneys and intestinal tract. The body can accumulate lead in bone cells, where it acts on the bone marrow. It can also interfere with the biochemical reactions that produce the iron-containing heme group in hemoglobin. In tissues, lead behaves like other heavy-metal poisons. When lead ions are bound to an enzyme, the enzyme will likely cease to function.

The principal sources of lead contamination now seem to be lead-based painted surfaces in old buildings and soldered joints in plumbing systems. The phasing out of leaded gasoline has resulted in a drastic drop in average lead blood levels. Mild formsof lead poisoning produce nervousness and mental depression. More severe cases can lead to permanent nerve, brain, and kidney damage.

BCIT Chemistry Resource Center
http://nobel.scas.bcit.ca/resource/