My complete seminar

EFFECTS, USES AND APPLICATIONS OF
LEAD
BY
AHMAD MUHAMMAD AHMAD
UG13CHM052
A SEMINAR REPORT SUBMITTED TO THE
DEPARTMENT OF CHEMISTRY, YUSUF MAITAMA SULE
UNIVERSITY, KANO, IN PARTIAL FULFILME NT OF THE
REQUIREMENTS FOR THE AWARD OF BACHELOR OF
SCIENCE (B.Sc.) DEGREE IN CHEMISTRY
NOVEMBER, 2017

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DEDICATION
This report is dedicated to Almighty Allah, for his mercies and blessing shown on me before,
during and after my program. I will also like to dedicate this report to my parents who stood by
me and also help me in many ways during the period of preparing this report.

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ACKNOWLEDGEMENT
Thank be to Almighty Allah for his blessing, guidance, protection, the courage and the
opportunity given to me to the successful completion of my seminar program, may his protection
and blessing continue to be with us (Amen). May the peace and blessing of Allah be upon our
beloved prophet Muhammad (S.A.W.), his family, companions and all those who follow the
right path till the Day of Judgement. (Amen)
I wish to express my thanks to my beloved parents for their support toward the completion of
this program. I also wish to acknowledge the effort of my supervisor Professor M.I Muhammad,
and the entire staff of Chemistry Department for their relevant suggestion and contribution
toward the completion of this program.

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ABTRACT
This report provides an overview of research, with the aim of offering more scientific detail on
the effects, uses and applications of lead in relation to its possible health impacts. This draws
attention to a number of studies on incidents of known effects, uses and applications of lead
contamination, most of which have been carried out in the past few decades.

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TABLE OF CONTENTS
Dedication …………………………………………………………..…………………………….i
Acknowledgement ……………………………………………………………………………… ii
Abstract ……………………………………………………………..……………………………iii
Chapter One
1.0 Introduction………………………………………………….…………………………… 1
1.1 Lead………………………………………………………………….…………………… 2
1.1.1 Physical Properties of Lead…………………………………………..………………….. 4
I Atomic……………………………………………..…………………………………… 4
II Bulk …………….………………………………………………………………………5
1.1.2 Isotopes of Lead ………………….……………………………………………………….6
1.1.3 Compounds of Lead…………………………………...……………...…………………. 8
I. Lead (II) Compound …………………………..………………………………………….9
II. Lead (IV) Compound…………………………..……………………………………….. 10
III. Other Oxidation S tate……………….…………..………………………..……………. 10
1.1.4 Effect of Lead……………………………………..……………………………………. 11
1.2 Aim and Objectives ………………….…………………………………….……………16
Chapter Two
2.0 Literature Review ……………………………………...…..…………………………….17

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Chapter Three
3.0 ApplicationofLead ………………….……………...……………………….……………...21
3.1 Conclusion ……………………………………………...…...……………………………....27
Reference…………………………………………………………..…………………………… 29

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LIST OF FIGURE
3.1 Industry Wise Use of Lead…………………………………………………………………21

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LIST OF PLATES
1.1 A sample of lead solidified from the molten state………………………………...………….5
3.1 Bricks of lead (alloyed with 4% antimony) are used as radiation shielding……..….………22
3.2 A ship made of lead to reduce corrosion…………………………………….………………23
3.3 A 17th-century gold-coated lead sculpture……………………………….…………….……24
3.4 lead battery…………………………….……………………………………………………..25
3.5 lead cable…………………………………………………………………………………….26

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CHAPTER ONE
1.0 INTRODUCTION
Lead is the most abundant of the heavy metals in the Earth’s crust. It has been used since
prehistoric times, and has become widely distributed and mobilized in the environment.
Exposure to and uptake of this non-essential element have consequently increased, Both
occupational and environmental exposures to lead remain a serious problem in many developing
and industrializing countries, as well as in some developed countries. In most developed
countries, however, introduction of lead into the human environment has decreased in recent
years, largely due to public health campaigns and a decline in its commercial usage, particularly
in petrol. Acute lead poisoning has become rare in such countries, but chronic exposure to low
levels of the metal is still a public health issue, especially among some minorities and
socioeconomically disadvantaged groups. Even though in developing countries, awareness of the
public health impact of exposure to lead is growing but relatively few of these countries have
introduced policies and regulations for significantly combating the problem. (Tong et al 2001)
At high levels of human exposure there is damage to almost all organs and organ systems, most
importantly the central nervous system, kidneys and blood, culminating in death at excessive
levels. At low levels, haeme synthesis and other biochemical processes are affected,
psychological and neurobehavioural functions are impaired, and there is a range of other effects.
There is a long history of public exposure to lead in food and drink. Lead poisoning was
common in Roman times because of the use of lead in water pipes and earthenware containers,
and in wine storage. Lead poisoning associated with occupational exposure was first reported in
370 BC. It became common among industrial workers in the 19th and early 20th centuries, when
workers were exposed to lead in smelting, painting, plumbing, printing and many other industrial

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activities. In 1767, Franklin obtained a list of patients in La Charite´ Hospital in Paris who had
been admitted because of symptoms, which, although not recognized then, were evidently those
of lead poisoning. All the patients were engaged in occupations that exposed them to lead. In
1839, Tanqueral des Planches described the symptoms of acute lead poisoning on the basis of
1213 admissions to La Charite´ Hospital between 1830 and 1838. His study was so thorough that
little has subsequently been added to the clinical picture of the symptoms and signs of acute lead
poisoning in adults. In the mid-19th century, occupational lead poisoning was a common
disorder in the United Kingdom, and in 1882, following the deaths of several employees in the
lead industry. A parliamentary enquiry was initiated into working conditions in lead factories.
This resulted in the 1883 Factory and Workshop Act (Prevention of Lead Poisoning), which
required lead factories to conform to certain minimum standards, e.g. the provision of ventilation
and protective clothing. Various adverse effects of lead exposure on human health have been
recognized. The working environment in the lead industry, especially in developed countries, has
been much improved. (Tong et al 2001)
1.1 LEAD
Lead is a chemical element that is assigned the symbol Pb (from the Latin plumbum) and the
atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft
and malleable, and has a relatively low melting point. When freshly cut, lead is bluish-white; it
tarnishes to a dull gray color when exposed to air. Lead has the highest atomic number of any
stable element and concludes three major decay chains of heavier elements. ( Meija et al. 2016.)
Lead is a relatively unreactive post-transition metal. Its weak, metallic character is illustrated by
its amphoteric nature; lead and lead-oxides react with acids and bases, and it tends to form
covalent bonds. Compounds of lead are usually found in the +2 oxidation state rather than the +4

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state common with lighter members of the carbon group. Exceptions are mostly limited to
organolead compounds. Like the lighter members of the group, lead tends to bond with itself; it
can form chains, rings and polyhedral structures. (Meija et al. 2016)
Lead is easily extracted from its ores; prehistoric people in Western Asia knew of it. Galena, a
principal ore of lead, often bears silver, interest in which helped initiate widespread extraction
and use of lead in ancient Rome. Lead production declined after the fall of Rome and did not
reach comparable levels until the Industrial Revolution. In 2014, annual global production of
lead was about ten million tones, over half of which was from recycling. Lead's high density, low
melting point, ductility and relative inertness to oxidation make it useful. These properties,
combined with its relative abundance and low cost, resulted in its extensive use in construction,
plumbing, batteries, bullets and shot, weights, solders, pewter’s, fusible alloys, white paints,
leaded gasoline, and radiation shielding.( Meija et al. 2016.)
In the late 19th century, lead's toxicity was recognized, and its use has since been phased out of
many applications. Lead is a neurotoxin that accumulates in soft tissues and bones, damages the
nervous system, and causes blood disorders. It is particularly problematic in children: even if
blood levels are promptly normalized with treatment, permanent brain damage may persist.
(Meija et al. 2016)
1.1.1 PHSICAL PROPERTIES
I. ATOMIC:
A lead atom has 82 electrons, arranged in an electron configuration of [Xe] 4f14 5d10 6s2 6p2. The
combined first and second ionization energies the total energy required to remove the two 6p
electrons is close to that of tin, lead's upper neighbor in the carbon group. This is unusual;

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ionization energies generally fall going down a group, as an element's outer electrons become
more distant from the nucleus, and more shielded by smaller orbitals. The similarity of ionization
energies is caused by the lanthanide contraction the decrease in element radii from lanthanum
(atomic number 57) to lutetium (71), and the relatively small radii of the elements after hafnium
(72). This is due to poor shielding of the nucleus by the lanthanide 4f electrons. The combined
first four ionization energies of lead exceed those of tin, contrary to what periodic trends would
predict. Relativistic effects, which become significant in heavier atoms, contribute to this
behavior. One such effect is the inert pair effect: the 6s electrons of lead become reluctant to
participate in bonding, making the distance between nearest atoms in crystalline lead unusually
long. (Sharma et al. 2013)
Lead's lighter carbon group congeners form stable or metastable allotropes with the tetrahedral
coordinated and covalently bonded diamond cubic structure. The energy levels of their outer s-
and p-orbitals are close enough to allow mixing into four hybrid sp3 orbitals. In lead, the inert
pair effect increases the separation between its s- and p-orbitals, and the gap cannot be overcome
by the energy that would be released by extra bonds following hybridization. Rather than having
a diamond cubic structure, lead forms metallic bonds in which only the p-electrons are
delocalized and shared between the Pb2+ ions. Lead consequently has a face-centered cubic
structure like the similarly sized divalent metals calcium and strontium. (Sharma et al. 2013)
II BULK:
Pure lead (plate 1.1) has a bright silvery appearance with a hint of blue. It tarnishes on contact
with moist air, and takes on a dull appearance the hue of which depends on the prevailing

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conditions. Characteristic properties of lead include high density, malleability, and high
resistance to corrosion (due to passivation).
Plate 1.1: A sample of lead solidified from the molten state.
Lead's close-packed face-centered cubic structure and high atomic weight result in a density of
11.34 g/cm3, which is greater than that of common metals such as iron (7.87 g/cm3), copper (8.93
g/cm3), and zinc (7.14 g/cm3). This density is the origin of the idiom to go over like a lead
balloon. Some rarer metals are denser: tungsten and gold are both 19.3 g/cm3, and osmium—the
densest metal known has a density of 22.59 g/cm3, almost twice that of lead. (Sharma et al.
2013)
Lead is a very soft metal with a Mohs hardness of 1.5; it can be scratched with a fingernail. It is
quite malleable and somewhat ductile. The bulk modulus of lead a measure of its ease of
compressibility is 45.8 GPa. In comparison, that of aluminium is 75.2 GPa; copper 137.8 GPa;
and mild steel 160–169 GPa. Lead's tensile strength, at 12–17 MPa, is low (that of aluminium is

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6 times higher, copper 10 times, and mild steel 15 times higher); it can be strengthened by
adding small amounts of copper or antimony. (Sharma et al. 2013)
The melting point of lead at 327.5 °C (621.5 °F) is very low compared to most metals. Its boiling
point of 1749 °C (3180 °F) is the lowest among the carbon group elements. The electrical
resistivity of lead at 20 °C is 192 nanoohm-meters, almost an order of magnitude higher than
those of other industrial metals (copper at 15.43 nΩ·m; gold 20.51 nΩ·m; and aluminium at
24.15 nΩ·m).Lead is a superconductor at temperatures lower than 7.19 K; this is the highest
critical temperature of all type-I superconductors and the third highest of the elemental
superconductors. (Sharma et al. 2013)
1.1.2 Isotopes of Lead
Natural lead consists of four stable isotopes with mass numbers of 204, 206, 207, and 208, and
traces of five short-lived radioisotopes. The high number of isotopes is consistent with lead's
atomic number being even. Lead has a magic number of protons (82), for which the nuclear shell
model accurately predicts an especially stable nucleus. Lead-208 has 126 neutrons, another
magic number, which may explain why lead-208 is extraordinarily stable. (Greenwood and
Earnshaw 1998)
With its high atomic number, lead is the heaviest element whose natural isotopes are regarded as
stable. This title was formerly held by bismuth, with an atomic number of 83, until its only
primordial isotope, bismuth-209, was found in 2003 to decay very slowly. The four stable
isotopes of lead could theoretically undergo alpha decay to isotopes of mercury with a release of
energy, but this has not been observed for any of them; their predicted half-lives range from
1035 to 10189 years. (Greenwood and Earnshaw 1998)

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Three of the stable isotopes are found in three of the four major decay chains: lead-206, lead-
207, and lead-208 are the final decay products of uranium-238, uranium-235, and thorium-232,
respectively. These decay chains are called the uranium series, the actinium series, and the
thorium series. Their isotopic concentration in a natural rock sample depends greatly on the
presence of these three parent uranium and thorium isotopes. For example, the relative
abundance of lead-208 can range from 52% in normal samples to 90% in thorium ores; for this
reason, the standard atomic weight of lead is given to only one decimal place. As time passes, the
ratio of lead-206 and lead-207 to lead-204 increases, since the former two are supplemented by
radioactive decay of heavier elements while the latter is not; this allows for lead–lead dating. As
uranium decays into lead, their relative amounts change; this is the basis for uranium–lead
dating. (Greenwood and Earnshaw 1998)
The Holsinger meteorite is the largest piece of the Canyon Diablo meteorite. Uranium–lead
dating and lead–lead dating on this meteorite allowed refinement of the age of the Earth to 4.55
billion ± 70 million years.
Apart from the stable isotopes, which make up almost all lead that exists naturally, there are trace
quantities of a few radioactive isotopes. One of them is lead-210; although it has a half-life of
only 22.3 years, small quantities occur in nature because lead-210 is produced by a long decay
series that starts with uranium-238 (which has been present for billions of years on Earth). Lead-
211, -212, and -214 are present in the decay chains of uranium-235, thorium-232, and uranium-
238, respectively, so traces of all three of these lead isotopes are found naturally. Minute traces
of lead-209 arise from the very rare cluster decay of radium-223, one of the daughter products of
natural uranium-235. Lead-210 is particularly useful for helping to identify the ages of samples

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by measuring its ratio to lead-206 (both isotopes are present in a single decay chain).
(Greenwood and Earnshaw 1998)
In total, 43 lead isotopes have been synthesized, with mass numbers 178–220. Lead-205 is the
most stable radioisotope, with a half-life of around 1.5×107 years. The second-most stable is
lead-202, which has a half-life of about 53,000 years, longer than any of the natural trace
radioisotopes. (Greenwood and Earnshaw 1998)
1.1.3 COMPOUNDS OF LEAD
Lead shows two main oxidation states: +4 and +2. The tetravalent state is common for the carbon
group. The divalent state is rare for carbon and silicon, minor for germanium, important (but not
prevailing) for tin, and is the more important for lead. This is attributable to relativistic effects,
specifically the inert pair effect, which manifests itself when there is a large difference in
electronegativity between lead and oxide, halide, or nitride anions, leading to a significant partial
positive charge on lead. The result is a stronger contraction of the lead 6s orbital than is the case
for the 6p orbital, making it rather inert in ionic compounds. This is less applicable to
compounds in which lead forms covalent bonds with elements of similar electronegativity such
as carbon in organolead compounds. In these, the 6s and 6p orbitals remain similarly sized and
sp3 hybridization is still energetically favorable. Lead, like carbon, is predominantly tetravalent
in such compounds. (Thornton et al. 2001)
There is a relatively large difference in the electronegativity of lead (II) at 1.87 and lead (IV) at
2.33. This difference marks the reversal in the trend of increasing stability of the +4 oxidation
state going down carbon group; tin, by comparison, has values of 1.80 in the +2 oxidation state
and 1.96 in the +4 state. (Thornton et al. 2001)

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i. LEAD (II) COMPOUND
Lead (II) compounds are characteristic of the inorganic chemistry of lead. Even strong oxidizing
agents like fluorine and chlorine react with lead to give only PbF2 and PbCl2. Lead(II) ions are
usually colorless in solution, and partially hydrolyze to form Pb(OH)+ and finally Pb4(OH)4 (in
which the hydroxyl ions act as bridging ligands), but are not reducing agents as tin(II) ions are.
Techniques for identifying the presence of the Pb2+ ion in water generally rely on the
precipitation of lead (II) chloride using dilute hydrochloric acid. As the chloride salt is somewhat
soluble in water, the precipitation of lead (II) sulfide, by bubbling hydrogen sulfide through the
solution, is then attempted. (Anderson 1999)
Lead monoxide exists in two polymorphs, red α-PbO and yellow β-PbO, the latter being stable
only above around 488°C. It is the most commonly used compound of lead. Its lead (II)
hydroxide counterpart can only exist in solution; it is known to form plumbite anions. Lead
commonly reacts with heavier chalcogens. Lead sulfide is a semiconductor, a photoconductor,
and an extremely sensitive infrared radiation detector. The other two chalcogenides, lead
selenide and lead telluride, are likewise photoconducting. They are unusual in that their color
becomes lighter going down the group. Lead and oxygen in a tetragonal unit cell of lead (II, IV)
oxide. (Anderson 1999)
Lead dihalides are well-characterized; this includes the diastatide, and mixed halides, such as
PbFCl. The relative insolubility of the latter forms a useful basis for the gravimetric
determination of fluorine. The difluoride was the first solid ionically conducting compound to be
discovered (in 1834, by Michael Faraday).The other dihalides decompose on exposure to
ultraviolet or visible light, especially the diiodide. Many lead pseudohalides are known. Lead (II)

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forms an extensive variety of halide coordination complexes, such as [PbCl4]2, [PbCl6]4, and the
[Pb2Cl9] chain anion. (Anderson 1999)
Lead (II) sulfate is insoluble in water, like the sulfates of other heavy divalent cations. Lead (II)
nitrate and lead (II) acetate are very soluble, and this is exploited in the synthesis of other lead
compounds. (Anderson 1999)
ii. LEAD(IV)
Few inorganic lead (IV) compounds are known, and these exist only in highly acidic solutions.
Lead (II) oxide gives a mixed oxide on further oxidation, Pb3O4. It is described as lead (II, IV)
oxide, or structurally 2PbO·PbO2, and is the best-known mixed valence lead compound. Lead
dioxide is a strong oxidizing agent, capable of oxidizing hydrochloric acid to chlorine gas. This
is because the expected PbCl4 that would be produced is unstable and spontaneously decomposes
to PbCl2 and Cl2. Analogously to lead monoxide, lead dioxide is capable of forming plumbate
anions. Lead disulfide and lead diselenide are only stable at high pressures. Lead tetrafluoride, a
yellow crystalline powder, is stable, but less so than the difluoride. Lead tetrachloride (yellow
oil) decomposes at room temperature, lead tetrabromide is less stable still, and the existence of
lead tetraiodide is questionable. (Lide 2005)
iii. OTHER OXIDATION STATE:
Some lead compounds exist in formal oxidation states other than +4 or +2. Lead (III) may be
obtained, as an intermediate between lead (II) and lead (IV), in larger organolead complexes; this
oxidation state is not stable as both the lead (III) ion and the larger complexes containing it are
radicals. The same applies for lead (I), which can be found in such species. (Lide 2005)

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Numerous mixed lead (II, IV) oxides are known. When PbO2 is heated in air, it becomes Pb12O19
at 293 °C, Pb12O17 at 351 °C, Pb3O4 at 374 °C, and finally PbO at 605 °C. A further sesquioxide
Pb2O3 can be obtained at high pressure, along with several non-stoichiometric phases. Many of
them show defective fluorite structures in which some oxygen atoms are replaced by vacancies:
PbO can be considered as having such a structure, with every alternate layer of oxygen atoms
absent. (Lide 2005)
Negative oxidation states can occur as Zintl phases, as either free lead anions, as in Ba2Pb, with
lead formally being lead (IV), or in oxygen-sensitive ring-shaped or polyhedral cluster ions such
as the trigonal bipyramidal Pb52− ion, where two lead atoms are lead (I) and three are lead (0). In
such anions, each atom is at a polyhedral vertex and contributes two electrons to each covalent
bond along an edgefrom their sp3 hybrid orbitals, the other two being an external lone pair. They
may be made in liquid ammonia via the reduction of lead by sodium. (Lide 2005)
1.1.4 EFFECT OF LEAD
Lead moves into and throughout ecosystems. Atmospheric lead is deposited in vegetation,
ground and water surfaces. The chemical and physical properties of lead and the biogeochemical
processes within ecosystems will influence the movement of lead through ecosystems. The metal
can affect all components of the environment and can move through the ecosystem until it
reaches equilibrium. Lead accumulates in the environment, but in certain chemical environments
it will be transformed in such a way as to increase its solubility (e.g., the formations of lead
sulfate in soils), its bioavailability or its toxicity. The effects of lead at the ecosystem level are
usually seen as a form of stress (US EPA 1986).

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In general, there are three known ways in which lead can adversely affect ecosystems.
Populations of micro-organisms may be wiped out at soil lead concentrations of 1,000 parts per
million (ppm) or more, slowing the rate of decomposition of matter. Populations of plants,
micro-organisms and invertebrates may be affected by lead concentrations of 500 to 1,000 ppm,
allowing more lead-tolerant populations of the same or different species to take their place. This
will change the type of ecosystem present. At all ambient atmospheric concentrations of lead, the
addition of lead to vegetation and animal surfaces can prevent the normal biochemical process
that purifies and repurifies the calcium pool in grazing animals and decomposer organisms
(UNEP 1991).
Effects of lead on soil: It is known that lead accumulates in the soil, particularly soil with a high
organic content (US EPA 1986). Lead deposited on the ground is transferred to the upper layers
of the soil surface, where it may be retained for many years (up to 2000 years). In undisturbed
ecosystems, organic matter in the upper layer of soil surface retains atmospheric lead.
Atmospheric lead in the soil will continue to move into the micro-organism and grazing food
chains, until equilibrium is reached. Given the chemistry of lead in soil, the US EPA (1986)
suggests that the uneven distribution of lead in ecosystems can displace other metals from the
binding sites on the organic matter. It may hinder the chemical breakdown of inorganic soil
fragments and lead in the soil may become more soluble, thus being more readily available to be
taken up by plants. (US EPA 1986)
Effects of lead on plants: Plants on land tend to absorb lead from the soil and retain most of
this in their roots. There is some evidence that plant foliage may also take up lead (and it is
possible that this lead is moved to other parts of the plant). The uptake of lead by the roots of the

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plant may be reduced with the application of calcium and phosphorus to the soil. Some species
of plant have the capacity to accumulate high concentrations of lead (UNEP, WHO and ILO
1991).
The pores in a plant's leaves let in carbon dioxide needed for photosynthesis and emit oxygen.
Lead pollution coats the surface of the leaf and reduces the amount of light reaching it. This
results in stunting the growth or killing the plants by reducing the rate of photosynthesis,
inhibiting respiration, encouraging an elongation of plant cells influencing root development 0;
by causing pre-mature aging. Some evidence suggests that lead can affect population genetics.
All these effects have been observed in isolated cells or in hydroponically grown plants in
solutions of around 1-2 ppm of lead in soil moisture e.g., the lead levels experienced by
ecosystems near smelters or roadsides). Lead in air may be transferred to plants directly through
fallout or indirectly through up-take from the soil. The pattern and degree of lead accumulation
are largely influenced by the state of growth of the vegetation; i.e., active growth periods in
spring as compared to low growth periods through autumn and winter. (US EPA 1986)
Effects of lead on micro-organisms: Evidence exists to show that lead at the concentrations
occasionally found near roadsides (i.e., 10,000 - 40,000 ppm dry weight), can wipe out
populations of bacteria and fungi on leaf surfaces and in soil. This can have a significant impact,
given that many of these micro-organisms are an essential part of the decomposing food chain.
The micro-organism populations affected are likely to be replaced by others of the same or
different species, although these may be less efficient at decomposing organic matter. Evidence
also suggests that micro-organisms can make lead more soluble and hence more easily absorbed

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by plants. That is, bacteria exude organic acids that lower the pH in the immediate vicinity of the
plant root. (Gale and Totemeier 2003)
Effects of lead on animals: Lead affects the central nervous system of animals and inhibits
their ability to synthesize red blood cells. Lead blood concentrations of above 40 µg/dl can
produce observable clinical symptoms in domestic animals. Calcium and phosphorus can reduce
the intestinal absorption of lead (US EPA 1986). The US EPA report generalizes that a regular
diet of 2-8 mg of lead per kilogram of body weight per day, over an extended period of time, will
cause death in most animals. Grazing animals are directly affected by the consumption of forage
and feed contaminated by airborne lead and somewhat indirectly by the up-take of lead through
plant roots. Invertebrates may also accumulate lead at levels toxic to their predators. (US EPA
1986)
Lead shot and lead weight can severely affect individual organisms and threaten ecosystems
(WHO 1989). After three to ten days of waterfowl ingesting lead shot, the poison will reach the
bloodstream and be carried to major organs, like the heart, liver and kidneys. By the 17th to 21st
day the bird falls into a coma and dies. Following the ingestion of lead shot, lead toxicosis has
been observed in Magpie geese, Black swans, several species of duck (including Black duck and
Musk duck) and Hardhead species.Organic lead is much more readily taken up by birds and fish
(WHO 1989). Aquatic organisms take up inorganic lead through a transfer of lead from water
and sediments; this is a relatively slow process. Organic lead is rapidly taken up by aquatic
organisms from water and sediment. Aquatic animals are affected by lead at water concentrations
lower than previously thought safe for wildlife. These concentrations occur often, but the impact
of atmospheric lead on specific sites with high aquatic lead levels is not clear (US EPA 1986)

15
Effect on the Nervous System: Compared to other organ systems, the nervous system appears to
be the most sensitive and chief target for lead induced toxicity. Both the central nervous system
and the peripheral nervous system become affected on lead exposure. The effects on the
peripheral nervous system are more pronounced in adults while the central nervous system is
more prominently affected in children. Encephalopathy (a progressive degeneration of certain
parts of the brain) is a direct consequence of lead exposure and the major symptoms include
dullness, irritability, poor attention span, headache, muscular tremor, loss of memory and
hallucinations. More severe manifestations occur at very high exposures and include delirium,
lack of coordination, convulsions, paralysis, coma and ataxia. Fetuses and young children are
especially vulnerable to the neurological effects of lead as the developing nervous system
absorbs a higher fraction of lead. The proportion of systemically circulating lead gaining access
to the brain of children is significantly higher as compared to adults (Needleman et al. 2004).
Children may appear inattentive, hyperactive and irritable even at low lead exposure. Children
with greater lead levels may be affected with delayed growth, decreased intelligence, short-term
memory and hearing loss. At higher levels, lead can cause permanent brain damage and even
death (Cleveland et al. 2008). There is evidence suggesting that low level lead exposure
significantly affects IQs along with behavior, concentration ability and attentiveness of the child.
Repercussions of lead exposure on the peripheral nervous system have also been observed in the
form of peripheral neuropathy, involving reduced motor activity due to loss of myelin sheath
which insulates the nerves, thus seriously impairing the transduction of nerve impulses, causing
muscular weakness, especially of the exterior muscles, fatigue and lack of muscular co-
ordination (Sanders et al. 2009).

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Exposure routes for lead to the environment: The main sources of lead entering an ecosystem
are atmospheric lead (primarily from automobile emissions), paint chips, used ammunition,
fertilisers and pesticides and lead-acid batteries or other industrial products. The transport and
distribution of lead from major emission sources, both fixed and mobile, are mainly through air
(UNEP 1991). While most of the lead discharged into air falls out near the source, about 20
percent is widely dispersed. Studies have demonstrated that measurements of lead in Greenland
rose and fell with the rise and decline of use of alkyl-leaded petrol in the United States Eurasia
and Canada over the past century (Isotopic evidence for the source of lead in Greenland snows
since the late 1960s; K. J. R. Rosman, W. Chisholm, C. F. Boutron, J. P. Candelone & U.
Görlach; Nature 362, 333 - 335; 25 March 1993). The size of the lead particles will govern how
far they move from the source. (Needleman et al. 2004)
1.2 Aim and Objectives
The aim and objectives of this report is to offer more scientific detail for decision makers
regarding the possible health impacts of lead on soil. In order to draw attention to a number of
studies on incidents of known soil contamination by lead, most of which have been carried out in
the past few decades.

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CHAPTER TWO
2.0 LITERATURE REVIEW
M. Kurs et al (2002) conducted a research on lead exposure to the society. It was found that
many countries have initiated programmes to lower the level of lead in the environment, human
exposure to lead remains of concern to health care providers and public health officials
worldwide. For over 35 years the World Health Organization and the International Programme
on Chemical Safety have been concerned about the adverse effects on health of lead in the
environment. The evaluation of human health risks arising from food borne lead has been carried
out by the World Health Organization on four occasions since 1972. In addition, health-based
guidance values for lead in water, air and the workplace have been developed by various task
groups convened by the World Health Organization. Environmental Health Criteria 3: Lead,
published in 1977, examined the effects of lead on human health, and Environmental Health
Criteria 85: Lead – Environmental Aspects was published in 1989. During the past 10 years, a
large body of knowledge on the effects of lead on neurobehavioural development of children at
low levels of exposure has accumulated.
Further investigation was carried out by Patrick et al. (2006).The investigation focus on phasing
out of leaded gasoline for transportation vehicles between 1973 and 1995 and the removal of
lead from paint by federal mandate by 1978 have resulted in substantial lowering of mean blood
lead levels in all segments of the U.S. population. However, because lead is a persistent metal, it
is still present in the environment in water, brass plumbing fixtures, soil, dust, and imported
products manufactured with lead. Diagnosis of lead toxicity has traditionally been based on
significantly elevated blood lead levels. However, data now implicates low-level exposures and
blood lead levels previously considered normal as causative factors in cognitive dysfunction,

18
neurobehavioral disorders, neurological damage, hypertension, and renal impairment. Chelation
is the conventional recommendation in the case of blood levels associated with acute toxicity and
encephalopathic damage. Issues surrounding the assessment of body lead burden and the
consequences of low-level environmental exposure are critical in the treatment of chronic disease
related to lead toxicity. (Altern Med Rev 2006)
Shuangxing et al 2013 also reported in a clinical study of the effects of lead poisoning on the
intelligence and neurobehavioral abilities of children. Lead is a heavy metal and important
environmental toxicant and nerve poison that can destruction many functions of the nervous
system. Lead poisoning is a medical condition caused by increased levels of lead in the body.
Lead interferes with a variety of body processes and is toxic to many organs and issues,
including the central nervous system. It interferes with the development of the nervous system,
and is therefore particularly toxic to children, causing potentially permanent neural and cognitive
impairments. In this study, we investigated the relationship between lead poisoning and the
intellectual and neurobehavioral capabilities of children.
Neary1et al. (2010) reported that the adverse affects of high blood levels of lead are well
established. There is now data emerging which looks at lower blood levels of lead associated
with poor cognition and other developmental concerns. The authors undertook a literature review
to examine the causal effect of low lead level and impaired cognitive function. The plausibility
of including lead screening as part of developmental delay workup in Ireland is also explored.
This review concludes that there is an adverse relationship between increasing level of lead and
cognition. Children with developmental delay would be at an increased risk to the cognitive
impairment associated with low levels of lead. Given that there are preventative and therapeutic
options to minimize the effects of lead, we argue that this group of children should be routinely

19
screened for lead. Currently there is lack of prevalence data in Ireland. The authors are working
in conjunction with British Paediatric Surveillance Unit Project to undertake active surveillance
of lead poisoning in Ireland.
Moreover, another research was conducted in 2003 base on deaths related to lead poisoning in
the United States by Kaufmann RB1, Staes CJ and Matte TD. The study was conducted to
describe trends in US lead poisoning-related deaths between 1979 and 1998. The predictive
value of relevant ICD-9 codes was also evaluated. Multiple cause-of-death files were searched
for records containing relevant ICD-9 codes, and underlying causes and demographic
characteristics were assessed. For 1979-1988, death certificates were reviewed; lead source
information was abstracted and accuracy of coding was determined. An estimated 200 lead
poisoning-related deaths occurred from 1979 to 1998. Most were among males (74%), Blacks
(67%), adults of age >/=45 years (76%), and Southerners (70%). The death rate was significantly
lower in more recent years. An alcohol-related code was a contributing cause for 28% of adults.
Only three of nine ICD-9 codes for lead poisoning were highly predictive of lead poisoning-
related deaths. In conclusion, lead poisoning-related death rates have dropped dramatically since
earlier decades and are continuing to decline. However, the findings imply that moonshine
ingestion remains a source of high-dose lead exposure in adults.
D'souza et al (2007) conducted an investigation on evaluation, diagnosis, and treatment of lead
poisoning in a patient with occupational lead exposure. Amongst toxic heavy metals, lead ranks
as one of the most serious environmental poisons all over the world. Exposure to lead in the
home and the workplace results in health hazards to many adults and children causing economic
damage, which is due to the lack of awareness of the ill effects of lead. We report the case of a
22 year old man working in an unorganized lead acid battery manufacturing unit, complaining

20
about a longer history of general body ache, lethargy, fatigue, shoulder joint pain, shaking of
hands and wrist drop. Patient had blue line at gingivodental junction. Central nervous system
(CNS) examination showed having graded 0 powers of extensors of right wrist & fingers.
Reflexes: Supinator- absent, Triceps- weak and other deep tendon reflexes- normal.
Investigations carried out during the admission showed hemoglobin levels of 8.3 g/dl and blood
lead level of 128.3μg/dl. The patient was subjected to chelation therapy, which was accompanied
by aggressive environmental intervention and was advised not to return to the same
environmental exposure situation. After repeated course of chelation therapy he has shown the
signs of improvement and is on follow up presently.

21
CHAPTER THREE
3.0 APPLICATION OF LEAD
Lead is widely used in batteries, cable sheaths, machinery manufacturing, shipbuilding, light
industry, lead oxide, radiation protection and other industries. Contrary to popular belief, pencil
leads in wooden pencils have never been made from lead. When the pencil originated as a
wrapped graphite writing tool, the particular type of graphite used was named plumbago
(literally, act for lead or lead mockup). (Donnelly et al 2014)
Figure 3.1: Industry wise use of lead

22
3.1 Elemental form
Lead metal (Plate 3.1) has several useful mechanical properties, including high density, low
melting point, ductility, and relative inertness. Many metals are superior to lead in some of these
aspects but are generally less common and more difficult to extract from parent ores. Lead's
toxicity has led to its phasing out for some uses.
As lead has radiation resistance, it can be used by hospital personnel and some other workers
who work in high radiation environments to protect them from its effects. In addition, it can also
be used in the post and telecommunications industries, metallurgy, chemical industry, railways,
transportation, construction, weapons, aerospace, aviation, oil and other industries (Graedel et al
2010.)
Plate 3.1: Bricks of lead (alloyed with 4% antimony) are used as radiation shielding.

23
Lead has been used for bullets since their invention in the middle Ages. Its inexpensive; its low
melting point means small arms ammunition and shotgun pellets can be cast with minimal
technical equipment; and it is denser than other common metals, which allows for better
retention of velocity. Concerns have been raised that lead bullets used for hunting can damage
the environment. (Rieuwerts et al 2015)
Its high density and resistance to corrosion have been exploited in a number of related
applications. It is used as ballast in sailboat keels. Its weight allows it to counterbalance the
heeling effect of wind on the sails; being so dense it takes up a small volume and minimizes
water resistance. It is used in scuba diving weight belts to counteract the diver's buoyancy. In
1993, the base of the Leaning Tower of Pisa (plate 3.2) was stabilized with 600 tonnes of
lead.[Because of its corrosion resistance, lead is used as a protective sheath for underwater
cables, lead plate, plumbing and other alloy materials to protect ships from marine corrosion in
shipbuilding.
Plate 3.2: A SHIP MADE OF LEAD TO REDUCE CORROSION

24
Lead has many uses in the construction industry; lead sheets are used as architectural metals in
roofing material, cladding, flashing, gutters and gutter joints, and on roof parapets. Detailed lead
moldings are used as decorative motifs to fix lead sheet. Lead is still used in statues and a
sculpture, including for armatures In the past it was often used to balance the wheels of cars; for
environmental reasons this use is being phased out in favor of other materials. (Davidson et al.
2014)
Plate 3.3: A 17th-century gold-coated lead sculpture
Lead is added to copper alloys such as brass and bronze, to improve machinability and for its
lubricating qualities. Being practically insoluble in copper the lead forms solid globules in
imperfections throughout the alloy, such as grain boundaries. In low concentrations, as well as
acting as a lubricant, the globules hinder the formation of swarf as the alloy is worked, thereby
improving machinability. Copper alloys with larger concentrations of lead are used in bearings.
The lead provides lubrication, and the copper provides the load-bearing support. (Bunker and
Casey 2014)
Lead's high density, atomic number, and formability form the basis for use of lead as a barrier
that absorbs sound, vibration, and radiation. Lead has no natural resonance frequencies; as a

25
result, sheet-lead is used as a sound deadening layer in the walls, floors, and ceilings of sound
studios. Organ pipes are often made from a lead alloy, mixed with various amounts of tin to
control the tone of each pipe. Lead is an established shielding material from radiation in nuclear
science and in X-ray rooms due to its denseness and high attenuation coefficient. Molten lead
has been used as a coolant for lead-cooled fast reactors. (Bunker and Casey 2014)
The largest use of lead in the early 21st century is in lead–acid batteries. The reactions in the
battery between lead, lead dioxide, and sulfuric acid provide a reliable source of voltage. The
lead in batteries undergoes no direct contact with humans, so there are fewer toxicity concerns.
Super capacitors incorporating lead–acid batteries have been installed in kilowatt and megawatt
scale applications in Australia, Japan, and the United States in frequency regulation, solar
smoothing and shifting, wind smoothing, and other applications. These batteries have lower
energy density and charge-discharge efficiency than lithium-ion batteries, but are significantly
cheaper. (Brenner et al. 2003)
Plate 3.4: lead battery
Lead is used in high voltage power cables as sheathing material to prevent water diffusion into
insulation; this use is decreasing as lead is being phased out. Its use in solder for electronics is
also being phased out by some countries to reduce the amount of environmentally hazardous

26
waste Lead is one of three metals used in the Oddy test for museum materials, helping detect
organic acids, aldehydes, and acidic gases. (Brenner et al. 2003)
Plate 3.5 lead cable

27
3.2 CONCLUSION
Exposure to environmental lead is clearly a major public health hazard of global dimensions. As
measures to control the transfer of lead to the environment are implemented in most developed
countries through, for example, the phasing out of lead in fuel, paints and other consumer
products, and tighter control of industrial emissions, environmental exposure to lead can, in
general, be expected to continue to decline. However, because of rapid industrialization and the
persistence of lead in the environment, exposure is likely to remain a significant public health
problem in most developing countries for many years. Much work needs to be done to identify
and treat children with elevated blood lead levels and reduce lead exposure in the community.
Screening, monitoring, intervention and evaluation are critical for the development of rational,
cost-effective and science-based public health policies aimed at achieving these goals.
Among the many international conventions that have acknowledged the importance of exposure
to lead as a key public health issue are the following:
1) The 1989 Convention on the Rights of the Child.
2) Agenda 21 adopted by the United Nations Conference on Environment and Development in
1992.
3) The 1997 Declaration on the Environment by the Leaders of the Eight (on Environmental
Health).
4) The OECD Declaration on Lead Risk Reduction.
Public health measures should continue to be directed to the reduction and prevention of
exposure to lead by reducing the use of the metal and its compounds and by minimizing lead-
containing emissions that result in human exposures. This can be achieved by:
1) Phasing out lead additives in fuels and removing lead from petrol as soon as is practicable.

28
2) Reducing and phasing out the use of lead-based paints.
3) Eliminating the use of lead in food containers.
4) Identifying, reducing and eliminating lead used in traditional medicines and cosmetics.
5) Minimizing the dissolving of lead in water treatment and water distribution systems.
6) Improving control over exposure to lead in workplaces.
7) Improving identification of populations at high risk of exposure on the basis of monitoring
systems.
8) Improving procedures of health risk assessment.
9) Improving promotion of understanding and awareness of exposure to lead.
10) Increasing emphasis on adequate nutrition, health care and attention to socioeconomic
conditions that may exacerbate the effects of lead.

29
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