Lead

Lead Ingot. Pitcher, Oklahoma, USA. University of Waterloo Earth Sciences Museum Collection.

Exposure to even small amounts of lead can be harmful since lead has no use in the body. Elevated levels and long term exposure of lead is linked to blood and kidney problems, as well as neurological disorders. As a result, its use in some applications has been discontinued. At one time, the fuel industry was among the major users of lead. Before gasoline is ignited in the engine, it is compressed, but under heavy compression the gasoline detonates without having been ignited. Tetraethyl (anti-knock) lead was added to gasoline to prevent detonations and ensured that the fuel burned evenly. However, tetraethyl lead has been eliminated from gasoline products because of the tremendous amounts of lead discharged by engines into the atmosphere. 

Three thousand years ago people used lead to make paint. Pieces of lead were placed on top of a cask containing a solution of vinegar with branches of shrubs arranged over the solution and the cask was covered tightly. After a while, white substance (white lead) would emerge on the surface and this was scraped off the metal and used as paint. Most old buildings dating back 100 years or more were painted with lead paint. In Britain, people would use white lead paint on window frames and doors. After one week of exposure to the sulphur in the air (from coal fires and industry) the paint turned completely black due to the white lead altering into galena (lead sulphide). Paint was washed regularly, and turned black again within a few days. Non-toxic titanium compounds have replaced lead used in paints. 

Lead mines in Missouri, Alaska, Colorado, Idaho and Montana produce the majority of lead recovered in the U.S. followed by Canada, which is the second largest producer of lead. Lead and zinc are formed in the same types of ore deposits.

More than seventy six percent of the lead consumed annually is used to make batteries for cars, trucks and other vehicles. Another twenty percent of the lead is used in electronics and communications (cell phone batteries, for example), ammunition, television glass, construction and protective coatings. A small amount is used to make protective aprons for patients having x-rays to shield the body from excess radiation exposure. Lead has the highest recycling rate of all industrial metals in the world because lead is easily re-melted and refined. More than 95% of the batteries used in the automotive industry are recycled.

Galena. Joplin, Missouri, USA. University of Waterloo Earth Sciences Museum Collection.

Uses of lead

• Alloying
• Ammunition
• Batteries
• Bearing Plates
• Cable Covering
• Ceramics
• Corrosion resistant tank linings for chemical processing
• Storage and transport equipment
• Electrical filters
• Gaskets
• Glass gramophone pick-ups
• Insecticides
• Lead crystal glass
• Lead solder used in electronic circuitry
• Leceling shims
• Non-spark flooring
• Paints (lead was used in paints in the past)
• Plumbing
• Radiation shield protects against X-rays, CAT scans, nuclear reactors and TV and Computer screens
• Roofing
• Sound absorber
• Sensors
• Seat belt pendulum
• Shower pans
• Spark generators
• Weights
• Toys (in the past and occasionally we reciece customer warning about toys containing lead today, mainly inexpensive jewellery)
• Wine bottles- metal foil capsule

Lead plays a vital role in electronic industry, in space exploration and telecommunications. Without the use of lead solders and leaded glass you would not be able to safely sit in front of your computer. Lead alloy solders enable your computer to send electronic data. It is the glue that binds our electronic world together. 

NASA's space shuttle uses lead-alloy solder of connecting transistors, relays and other electronic components because it is the most reliable way of soldering materials together. In addition, lead glazes are used to encapsulate and protect the electronic microcircuits from atmospheric corrosion.

Lead c​rystal

Lead crystal glass was developed in the 17th century by combining molten quartz with lead. The final product usually contains 24 to 36 percent lead oxide. It is widely used today for serving beverages such as wine and alcohol. Lead crystal is known for its brilliance and clarity. However, there are some health risks associated with using lead crystal. When lead crystal comes in contact with acidic beverages, some lead dissolves into the liquid. As well, any container you drink from that has an exterior decorative pattern around the rim, such as a coating or glaze, may also release lead. The amount of lead dissolved into the liquid depends on the type of beverage and length of time they are in contact. Alcoholic beverages such as wine and non-alcoholic beverages such as fruit juices and soft drinks also absorb lead. However, the actual amount of lead released from crystal glasses over the course of a normal meal tends to be very low. 

Beverages stored in crystal decanters for weeks and months can accumulate very high levels of lead. Lead concentrations of up to 20 parts per million - 100 times higher than the Canadian limit have been found in wines kept for weeks or months in crystal containers. Manufactures are now coating the interior of some lead crystal containers to prevent lead from leaching in the beverage. It is also evident that washing crystal in harsh detergents such as dishwasher detergents can increase lead release into beverages. New lead crystal glasses should be cleaned by soaking in vinegar for more than 24 hours to prevent any lead contamination. Lead foil capsules were used to cover wine bottles but this has been discontinued due to the hazardous oxide remaining on the lip and neck of the bottle. 

Lead batteries

Lead-acid batteries represent sixty percent of batteries sold worldwide. Lead-acid batteries date back to 1860 when Raymond Gaston PlantŽ first invented them. Lead-acid batteries provide power for everything from forklifts to backup systems used in hospitals. All lead batteries work on the same set of reactions and use the same active materials. At the positive electrode, lead dioxide is converted to lead sulfate and at the negative electrode, sponge metallic lead is also converted to lead sulfate. The electrolyte is a dilute mixture of sulfuric acid that provides the sulfate ion for the discharge reactions. 

Lead paint

In the 1920's, children became the primary target of company's advertising campaign. Lead paint companies used children in their marketing strategy, to promote the use of lead paint in general public places and for interior wall uses. In the late 1920's, National Lead published a book called "The Dutch Boy's Lead Party" which also promoted the use of lead paint in schoolrooms and suggested that summer was the best time to get school officials to have the school rooms repainted. Advertising lead paint using children even became more important after information about lead paint's danger to children started to accumulate. The rigorous lead pigment campaign overshadowed the medical evidence concerning the dangers of lead to children, painters and manufactures of paint in the 1930's. One advertisement showed a child in a bathtub scrubbing himself with a brush. Another promotion depicted a crawling infant touching a painted wall. The clear message proclaimed by the advertisement was that it was safe for toddlers to touch walls and woodwork covered with lead paint. Until the mid 1950's, National Lead used the Dutch Boy image as a clever way of countering negative publicity by developing a campaign focusing on children.

Web resources

*The links were taken down as this article was published in Novemb​er 2003 and none of the websites used to write this article were still in use.