Lead



Lead is a chemical element with the symbol Pb and the atomic number 82. It is considered a heavy metal, although it is very soft and malleable. When exposed to air, it becomes dark gray, although it begins as a bluish color. Lead is used in building construction, lead acid batteries, bullets, and shot and as a radiation shields. Lead, at a certain level, is poisonous to humans because it damages the nervous system and causes brain disorders. Exposure to lead and lead chemicals can occur through inhalation, ingestion and dermal contact. Most exposure occurs through ingestion or inhalation; in the U.S. the __skin__ exposure is unlikely as leaded gasoline additives are no longer used. Lead exposure is a global issue as lead mining and lead smelting are common in many countries. Most countries have stopped using lead-containing gasoline by 2007.

History of Lead

 * Has been used for many years because it is..
 * 1. Easily extracted
 * 2. Easy to work with
 * Metallic lead beads date back to 6400 BCE!
 * (found in modern day Turkey)
 * The largest pre-industrial producer of lead products was the Roman empire and economy

Warm or hot tap water can contain very high levels of lead. Pregnant mothers can place their baby at risk if they drink tap water because of how it passes the placenta. The EPA states that water that contains any type of lead in it is not safe to drink. Infants and children can experience kidney damage if they are exposed to too much lead. This can also result in lower IQ levels in children.

Lead has a melting point of 600.65 ° K. Lead has a boiling point of 2013 ° K.

Common Uses for Lead Source:[]
 * the metal and the dioxide are used in storage batteries
 * cable covering, plumbing, ammunition
 * manufacture of PbEt 4 - an antiknock compound in petrol. Environmental concern with lead poisoning, (and cheaper unleaded petrol prices) is slowly resulting in less use of lead in petrol
 * the metal is very effective as a sound absorber
 * a radiation shield around __X-ray equipment__ and nuclear reactors
 * used extensively in paints, although recently the use of lead in paints has been drastically curtailed to eliminate or reduce health hazards
 * the oxide is used in producing fine "crystal glass" and "flint glass" with a high refractive index for achromatic lenses
 * solder
 * used by the Romans for plumbing (the decline of the Roman empire is attributed to lead in the water supply!)
 * used to contain corrosive liquids
 * alloying
 * cable covering
 * ammunition
 * shield against X-rays
 * oxide used to produce crystal glass
 * insecticides

There are many possible symptoms of lead poisoning. Lead can affect many different parts of the body. A single high dose of lead can cause severe emergency symptoms. However, it is more common for lead poisoning to build up slowly over time. This occurs from repeated exposure to small amounts of lead. In this case, there may not be any obvious symptoms. Over time, even low levels of lead exposure can harm a child's mental development. The health problems get worse as the level of lead in the blood gets higher. Lead is much more harmful to children than adults because it can affect children's developing nerves and brains. The younger the child, the more harmful lead can be. Unborn children are the most vulnerable. Possible complications include: The symptoms of lead poisoning may include: Very high levels of lead may cause vomiting, staggering walk, muscle weakness, seizures, or coma.
 * Behavior or attention problems
 * Failure at school
 * __Hearing problems__
 * Kidney damage
 * Reduced IQ
 * Slowed body growth
 * Abdominal pain and cramping (usually the first sign of a high, toxic dose of lead poison)
 * Aggressive behavior
 * Anemia
 * Constipation
 * Difficulty sleeping
 * Headaches
 * Irritability
 * Loss of previous developmental skills (in young children)
 * Low appetite and energy
 * Reduced sensations

Lead is highly poisonous metal (regardless if inhaled or swallowed), affecting almost every organ and system in the body. The main target for lead toxicity is the nervous system, both in adults and children. Long-term exposure of adults can result in decreased performance in some tests that measure functions of the nervous system. Long-term exposure to lead or its salts (especially soluble salts or the strong oxidant PbO2) can cause nephropathy, and colic-like abdominal pains. It may also cause weakness in fingers, wrists, or ankles. Lead exposure also causes small increases in blood pressure, particularly in middle-aged and older people and can cause anemia. Exposure to high lead levels can severely damage the brain and kidneys in adults or children and ultimately cause death. In pregnant women, high levels of exposure to lead may cause miscarriage. Chronic, high-level exposure have shown to reduce fertility in males. Lead also damages nervous connections (especially in young children) and cause blood and brain disorders. Lead poisoning typically results from ingestion of food or water contaminated with lead; but may also occur after accidental ingestion of contaminated soil, dust, or lead-based paint. It is rapidly absorbed into the bloodstream and is believed to have adverse effects on the central nervous system, the cardiovascular system, kidneys, and the immune system. The component limit of lead (1.0 μg/g) is a test benchmark for pharmaceuticals, representing the maximum daily intake an individual should have. However, even at this low level, a prolonged intake can be hazardous to human beings. The treatment for lead poisoning consists of dimercaprol and succimer.
 * Health Risks**

Lead used to be added to gasoline/petrol in the form of tetraethyl lead. In such a form, it was an "anti-knock" agent, which meant that it smoothed the combustion of the fuel and made the vehicle run better. Has been banned or in the process of being banned by most developed countries, due to the toxic effects of the lead emissions. Thus today's "unleaded" gas you see at the pump.
 * Interesting Fact About Lead:**

Compounds
Lead compounds are used as a coloring element in ceramic glazes, notably in the colors red and yellow Lead is frequently used in polyvinyl chloride (PVC) plastic, which coats electrical cords. Lead is used in some candles to treat the wick to ensure a longer, more even burn. Because of the dangers, European and North American manufacturers use more expensive alternatives such as zinc Lead glass is composed of 12–28% lead oxide. It changes the optical characteristics of the glass and reduces the transmission of radiation. Some artists using oil-based paints continue to use lead carbonate white, citing its properties in comparison with the alternatives. Tetra-ethyl lead is used as an anti-knock additive for aviation fuel in piston-driven aircraft. Lead-based semiconductors, such as lead telluride, lead selenide and lead antimonide are finding applications in photovoltaic (solar energy) cells and infrared detectors

Did you Know?
The infamous lead pencil actually contains No lead? It's blacken core is actually graphite!