Chemical Properties
grey metal granules, shot, foil, sheet or powder
Uses
Construction material for tank linings, piping, and other equipment handling corrosive gases and liqs used in the manufacture of sulfuric acid, petroleum refining, halogenation, sulfonation, extraction, condensation; for x-ray and atomic radiation protection; manufacture of tetraethyllead, pigments for paints, and other organic and inorganic lead Compounds; bearing metal and alloys; storage batteries; in ceramics, plastics, and electronic devices; in building construction; in solder and other lead alloys; in the metallurgy of steel and other metals.
General Description
Soft silver-bluish white to gray metal.
Reactivity Profile
In the presence of carbon, the combination of chlorine trifluoride with aluminum, copper, LEAD(7439-92-1), magnesium, silver, tin, or zinc results in a violent reaction [Mellor 2, Supp. 1: 1956]. A solution of sodium azide in copper pipe with LEAD(7439-92-1) joints formed copper and LEAD(7439-92-1) azide, both are detonating compounds [Klotz 1973]. Sodium acetylide becomes pyrophoric when mixed with metals like LEAD(7439-92-1). Mixtures of trioxane with 60% hydrogen peroxide in contact with metallic LEAD(7439-92-1) when heated detonated. LEAD(7439-92-1) containing rubber ignited in a nitric acid atmosphere. LEAD(7439-92-1) is incompatible with strong oxidants such as: ammonium nitrate, chlorine trifluoride, hydrogen peroxide, etc.
Health Hazard
The acute toxicity of lead and inorganic lead compounds is moderate to low.
Symptoms of exposure include decreased appetite, insomnia, headache, muscle and
joint pain, colic, and constipation. Inorganic lead compounds are not significantly
absorbed through the skin.
Chronic exposure to inorganic lead via inhalation or ingestion can result in damage
to the peripheral and central nervous system, anemia, and chronic kidney disease.
Lead can accumulate in the soft tissues and bones, with the highest accumulation in
the liver and kidneys, and elimination is slow. Lead has shown developmental and
reproductive toxicity in both male and female animals and humans. Lead is listed by
IARC in Group 2B ("possible human carcinogen") and by NTP as "reasonably
anticipated to be a carcinogen," but is not considered to be a "select carcinogen"
under the criteria of the OSHA Laboratory Standard.
Air & Water Reactions
Insoluble in water.
Fire Hazard
Flash point data for this compound are not available, however, LEAD is probably non-combustible.
Description
Lead was one of the earliest metals used by humans, with
possible use extending as far back as the seventh millennium
BC, and reaching its preindustrial peak usage during the
reign of the Roman Empire, around the beginning of the
Common Era.
Isotopes
There are 47 isotopes of lead, four of which are stable. One of these four is Pb-204, which makes up 1.4% of the natural abundance of lead found on Earth. In reality thisisotope is not stable but has a half-life that is so long (1.4×10+17 years), with some of theancient deposits still existing, that it is considered stable. The other three stable isotopes oflead and their proportion to the total natural abundance are as follows: Pb-206 = 24.1%,Pb-207 = 22.1%, and Pb-208 = 52.4%. All the other isotopes are radioactive.
Origin of Name
From the Latin word alumen, or aluminis, meaning “alum,” which is a
bitter tasting form of aluminum sulfate or aluminum potassium sulfate.
Occurrence
Lead is the 35th most abundant element on Earth. Although it has been found in its freeelemental metal state, it is usually obtained from a combination of the following ores: galena(PbS), anglesite (PbSO4), cerussite (PbCO3), and minum (Pb3O4). Lead ores are locatedin Europe (Germany, Rumania, and France), Africa, Australia, Mexico, Peru, Bolivia, andCanada. The largest deposits of lead in the United States are in the states of Missouri, Kansas,Oklahoma, Colorado, and Montana.
One of the most famous mining towns is the high-altitude western city of Leadville,Colorado. The boom started with the gold rush of the 1860s, followed by silver mining in the1870s and 1880s. Today, this city is the site of mining operations not only for lead, but alsofor zinc and molybdenum. At the height of its fame, Leadville had a population of almost50,000 people. Today the population is about 2,500.
Lead is commonly obtained by roasting galena (PbS) with carbon in an oxygen-rich environmentto convert sulfide ores to oxides and by then reducing the oxide to metallic lead.Sulfur dioxide gas is produced as a waste product. Large amounts of lead are also recoveredby recycling lead products, such as automobile lead-acid electric storage batteries. About onethirdof all lead used in the United States has been recycled.
Characteristics
Although lead can be found as a metal in the Earth’s crust, it is usually mined and refinedfrom minerals and ores. Lead is one of the most common and familiar metallic elementsknown. Although it is somewhat scarce, found at proportions of 13 ppm, it is still more prevalentthan many other metals. Lead is noncombustible. and it resists corrosion.
When lead, which is very soft, is freshly cut, it has shiny blue-white sheen, which soonoxidizes into its familiar gray color. Lead is extremely malleable and ductile and can be workedinto a variety of shapes. It can be formed into sheets, pipes, buckshot, wires, and powder.Although lead is a poor conductor of electricity, its high density makes it an excellent shieldfor protection from radiation, including X-rays and gamma rays.
Definition
lead: Symbol Pb. A heavy dull greysoft ductile metallic element belongingto group 14 (formerly IVB) ofthe periodic table; a.n. 82; r.a.m.207.19; r.d. 11.35; m.p. 327.5°C; b.p.1740°C. The main ore is the sulphidegalena (PbS); other minor sources includeanglesite (PbSO4), cerussite (PbCO3), and litharge (PbO). Themetal is extracted by roasting the oreto give the oxide, followed by reductionwith carbon. Silver is also recoveredfrom the ores. Lead has a varietyof uses including building construction,lead-plate accumulators, bullets,and shot, and is a constituent of suchalloys as solder, pewter, bearing metals,type metals, and fusible alloys.Chemically, it forms compoundswith the +2 and +4 oxidation states,the lead(II) state being the more stable.
Production Methods
The geometric mean soil lead level is 38 mg/kg. Lead
rarely occurs in the elemental state, but exists widely
throughout the world in a number of ores, the most common
of which is the sulfide, galena. The other minerals of commercial
importance are the oxides, carbonate (cerussite), and
the sulfate (anglesite), which are much less common.
Lead also occurs in various uranium and thorium minerals,
arising directly from radioactive decay. Because certain
isotopes are concentrated in lead derivatives from such
sources, both the atomic weight and the density of the
samples vary significantly from normal lead. Lead ores
generally occur in nature in association with silver and
zinc. Other metals commonly occurring with lead ores are
copper, arsenic, antimony, and bismuth. Most of the world production of arsenic, antimony, and bismuth is a result of
their separation from lead ores. Commercial lead ores may
contain as little as 3% lead, but a lead content of 10% is
most common. The ores are concentrated to ≥ 40% lead
content before smelting. A variety of mechanical separation
processes may be employed for the concentration of lead
ores, but the sulfide ores are generally concentrated by
flotation processes.
Hazard
Lead is probably one of the most widely distributed poisons in the world. Not only is themetal poisonous, but most lead compounds are also extremely toxic when inhaled or ingested.A few, such as lead alkalis, are toxic when absorbed through skin contact.
Workers in industries using lead are subject to testing of their blood and urine to determinethe levels of lead in their bodies’ organs. Great effort is made to keep the workers safe.
Unfortunately, many older homes (built prior to 1950) have several coats of lead-basedpaints that flake off, which then may be ingested by children, causing various degrees of leadpoisoning, including mental retardation or even death.
Young children are more susceptible to an accumulation of lead in their systems than areadults because of their smaller body size and more rapidly growing organs, such as the kidneys,nervous system, and blood-forming organs. Symptoms may include headaches, dizziness,insomnia, and stupor, leading to coma and eventually death.
Lead poisoning can also occur from drinking tap water contained in pipes that have beensoldered with lead-alloy solder. This risk can be reduced by running the tap water until it iscold, which assures a fresher supply of water.
Another hazardous source of lead is pottery that is coated with a lead glaze that is notstabilized. Acidic and hot liquids (citrus fruits, tea, and coffee) react with the lead, and eachuse adds a small amount of ingested lead that can be accumulative. Lead air pollution is stilla problem, but not as great as before, given that tetraethyl lead is no longer used in gasoline.However, lead air pollution remains a problem for those living near lead smelting operationsor in countries where leaded gasoline is still permitted.
Even though lead and many of its compounds are toxic and carcinogenic, our lives wouldbe much less satisfying without its use in our civilization.
Flammability and Explosibility
Lead powder is combustible when exposed to heat or flame.
Industrial uses
lead has been under investigation for use as anticancer and antimicrobial agent, but so far
with limited success.
Lead is obtained from its
sulfide (PbS, galena), which is first roasted in the presence of oxygen and then reduced with carbon to give
elemental Pb.
Lead is a greymetal and most lead is used in batteries.Other major uses, such as in plumbing or as antiknock
agent in petrol (tetraethyl lead, Pb(C2H5)4), have declined over recent years because of the high toxicity of
lead. Pb is a neurotoxin when ingested and many lead compounds are water soluble. Therefore, water lines
have been replaced by specialised plastic material, and in most industrialised countries only unleaded petrol
is sold.
Industrial uses
Not only is lead the most impervious of all common metals to x-rays and gamma radiation, it also resists attack by many corrosive chemicals, most types of soil, and marine and industrial environments. Although lead is one of the heaviest metals, only a few applications are based primarily on its high density. The main reasons for using lead often include low melting temperature, ease of casting and forming, good sound and vibration absorption, and ease of salvaging from scrap.
With its high internal damping characteristics, lead is one of the most efficient sound attenuators for industrial, commercial, and residential applications. Sheet lead, lead-loaded vinyls, lead composites, and lead-containing laminates are used to reduce machinery noise. Lead sheet with asbestos or rubber sandwich pads are commonly used in vibration control.
Potential Exposure
Tumorigen,Mutagen，Organometallic; Reproductive Effector; HumanData. Metallic lead is used for lining tanks, piping, andother equipment where pliability and corrosion resistance are required, such as in the chemical industry in handlingcorrosive gases and liquids used in the manufacture of sul-furic acid; in petroleum refining; and in halogenation, sulfo-nation，extraction， and condensation processes; and inbuilding industry. It is also used as an ingredient in solder,a body filler in the automobile industry, and a shieldingmaterial for X-rays and atomic radiation, in manufacture oftetraethyl lead and organic and inorganic lead compounds,pigments for paints and varnishes, storage batteries, flingglass, vitreous enameling, ceramics as a glaze, litharge rub-ber, plastics, and electronic devices. Lead is utilized in met-allurgy and may be added to bronze, brass, steel, and otheralloys to improve their characteristics. It forms alloys withantimony, tin, copper, etc. It is also used in metallizing toprov ide protective coatings and as a heat treatment bath inwire drawing. Exposures to lead dust may occur duringmining, smelting, refining, and to fume, during high tem-perature (> 500℃) operations, such as welding or spraycoating of metals with molten lead. There are numerousapplications for lead compounds, some of the more com-mon being in the plates of electric batteries and accumula-tors; as compounding agents irrubber manufacture; asingredients in paints, glazes, enamels, glass, pigments; andin the chemical industry. In addition, to these usual levelsof exposure from environmental media, there exist miscella-neous sources which are hazardous. The level of exposureresulting from contact is highly variable. Children with picafor paint chips or for soil may experience elevation in bloodlead, ranging from marginal to sufficiently great to causeclinical illness. Certain adults may also be exposed to haz-ardous concentrations of lead in the workplace, notably inlead smelters and storage battery manufacturing plants.Again, the range of exposure is highly variable. Women inthe workplace are more likely to ex perience adverse effectsfrom lead exposure than men due to the fact that theirhematopoietic system is more lead-sensitive than men.Because of health concerns, lead from gasoline, paints, andceramic products, caulking, and pipe solder, has been dra-matically reduced in recent years.
First aid
If this chemical gets into the eyes, remove anycontact lenses at once and irri gate immediately for at least15 min, occasionally lifting upper and lower lids. Seek med-ical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. When this chemical has been swal-lowed, get medical attention.Antidotes and special procedures: Persons with si gnificantlead poisoning are sometimes treated with Ca EDTA whilehospitalized. This “chelating” drug causes a rush of leadfrom the body organs into the blood and kidneys, and thushas its own hazards, and must be administered only byhighly experienced medical personnel under controlled con-ditions and careful observation. Ca EDTA or similar drugsshould never be used to prevent poisoning while exposurecontinues or without strict exposure control, as severe kid-ney damage can result.Note to physician: For severe poisoning BAL [British Anti-Lewisite, dimercaprol, dithiopropanol (C3HgOS2)] has beenused to treat toxic symptoms of certain heavy metals poi-soning. In the case of lead poisoning it may have SOMEvalue. Although BAL is reported to have a large margin ofsafety, caution must be exercised, because toxic effects maybe caused by excessive dosage. Most can be prevented bypremedication with 1-ephedrine sulfate (CAS: 134-72-5).
Carcinogenicity
Lead and lead compounds are reasonably anticipated to be human carcinogens based on limited evidence of carcinogenicity from studies in humans and sufficient evidence of carcinogenicity from studiesin experimental animals.
Environmental Fate
Lead in the earth’s crust is about 15–20 mg kg1. Lead occurs
naturally in the environment. However, most of the lead
dispersed throughout the environment comes from human
activities. Before the use of leaded gasoline was limited, most of
the lead released into the US environment came from car
exhaust. Because the EPA has limited the use of leaded gasoline,
the amount of lead released into the air has decreased. Other
sources of lead released into the air include burning fuel, such
as coal or oil, industrial processes, and burning solid waste.
The release of lead to air is now less than the release of lead to
soil. Most of the lead in inner city soils comes from landfills and
leaded paint. Landfills contain waste from lead ore mining,
ammunition manufacturing, and other industrial activities such
as battery production. Very little lead goes directly into water.
Higher levels of lead from car exhausts can be measured
near roadways. Very low levels of lead from car exhausts are
found at distances of 25m (82 ft) from the road edge.
However, once lead goes into the atmosphere, it may travel
thousands of miles if the lead particles are small or if the lead
compounds are volatile. Lead is removed from the air by rain as
well as by particles falling to the ground or into surface water.
Once lead deposits on soil, it usually sticks to soil particles.
Small amounts of lead may enter rivers, lakes, and streams
when soil particles are displaced by rainwater. Lead may
remain stuck to soil particles in water for many years. Movement
of lead from soil particles into underground water or
drinking water is unlikely unless the water is acidic or ‘soft.’
Some of the chemicals that contain lead are broken down
by sunlight, air, and water to other forms of lead. Lead
compounds in water may combine with different chemicals
depending on the acidity and temperature of the water. The
lead atom cannot be broken down.
The levels of lead may build up in plants and animals from
areas in which air, water, or soil are contaminated with lead. If
animals eat contaminated plants or animals, most of the lead
they eat will pass through their bodies. The small amount
absorbed can cause harmful effects. The amount of lead in
paints sold for consumer use may not exceed 0.06%.
Releases from lead-based paints are frequently confined to
the area in the immediate vicinity of painted surfaces, and
deterioration or removal of the paint can result in high localized
concentrations of lead in indoor air and on exposed
surfaces. Sandblasting procedures to remove paint may
disperse lead into the local environment.
The largest volume of organolead vapors released to the
atmosphere results from industrial processes such as primary
and secondary nonferrous metal smelting, and from the use of
leaded gasoline, which contains tetraethyl lead as an antiknock
additive. These vapors are photoreactive, and their presence
in the local atmosphere is transitory. Halogenated lead
compounds are also formed and, ultimately, oxides and
carbonates. Tetra-alkyl lead compounds have been found to
contribute 5–10% of the total particulate lead present in the
atmosphere. Organolead vapors are most likely to occur in
occupational settings (e.g., gasoline transport and handling
operations, gas stations, and parking garages) and high traffic
areas.
Although aquatic releases from industrial facilities are
expected to be small, lead may be present in significant levels in
drinking water. In areas receiving acid rain (e.g., northeastern
United States) the acidity of drinking water may increase, thus
increasing the corrosivity of the water, which may, in turn,
result in the leaching of lead from water systems, particularly
from older systems during the first flush of water through the pipes. Fish in more acidic waters accumulate more lead than fish in a more alkaline environment.
The grounding of household electrical systems to the
plumbing can increase corrosion rates and the subsequent
leaching of lead from the lead solder used for copper pipes.
Areas in which the pH of the water is <8.0 may have higher
lead drinking water levels as well.
Canning foods in lead-soldered cans may increase levels of
lead 8- to 10-fold; however, the impact of canning appears to
be decreasing as a result of a decrease in the use of leadsoldered
cans. Additional exposure to lead through dietary
intake by people living in an urban environment is estimated
to be ～ 28 mg day-1 for adults and 91mg day-1 for children,
all of which can be attributed to atmospheric lead (dust).
Atmospheric lead may be added to food crops in the field or
garden (through uptake from soil and from direct deposition
onto crop surfaces), during transport to market, processing, and
kitchen preparation.
Lead may leach from lead crystal decanters and glasses into
the liquids they contain. Flaking paint, paint chips, and
weathered powdered paint, which are most commonly associated
with deteriorated housing stock in urban areas, are major
sources of lead exposure for young children residing in these
houses, particularly for children with pica (i.e., the compulsive,
habitual consumption of nonfood items). Lead concentrations
of 1000–5000 mg cm-2 have been found in chips of lead-based
paint, suggesting that consumption of a single chip of paint
would provide greater short-term exposure than any other
source of lead.
storage
work with lead dust, molten lead, and lead salts capable of forming
dusts should be conducted in a fume hood to prevent exposure by inhalation.
Shipping
For Metal powder, flammable, n.o.s. the requiredlabel is“SPONTANEOUSLY COMBUSTIBLE." They fallinto Hazard Class 4.2 and Packing Group I
Toxicity evaluation
Lead can affect most organs and systems in the body. It can
interfere with certain cellular signaling processes, the generation
of action potentials in certain nerve cells, and the function of
a number of enzymes. Lead interferes with the sodium–
potassium ATPase pump on cell membranes, the metabolism of
vitamin D, heme synthesis, certain enzymes involved in oxidative
phosphorylation (cytochromes), and calcium uptake and
metabolism. In addition, lead can interfere with signal transmissions
in nerve cells, including dopaminergic transmissions
and signaling processes at the postsynaptic and presynaptic
junctions. Lead can depress the function of the adrenal glands
and the thyroid.
Lead binds certain active groups on protein (e.g., sulfhydryl
groups) and therefore may change the structure and function of
certain proteins and enzymes. Lead interferes with the
biosynthesis of heme in at least two steps in the multi-step
process. Heme proteins are important to the structure and
function of hemoglobin in red blood cells. Lead binds with
8-aminolevulinic acid dehydratase and depresses its activity.
This biochemical block explains the occurrence of anemia
found in chronic lead poisoning. Measurement of the blood
levels of this enzyme is used as a test for lead intoxication. Lead
also interferes with the incorporation of ferrous iron into the
porphyrin ring. If iron is not attached to heme, then zinc will
occupy the iron-binding site. The concentration of zinc protoporphyrin
also can be used as a diagnostic tool for lead
poisoning.
Incompatibilities
Violent reactions of lead with sodium azide, zirconium, sodium acetylide, and
chlorine trifluoride have been reported. Reactivity of lead compounds varies
depending on structure.
Waste Disposal
Excess lead and waste material containing this substance should be placed in an appropriate
container, clearly labeled, and handled according to your institution's waste disposal
guidelines. For more information on disposal procedures, see Chapter 7 of this volume.
