University of Nigeria Research Publications

Aut

hor

OKENYI, Calister Ekperechi

PG/M.Sc/05/40088

Title

Concentration of CADMIUM, Lead and

Chromium in Human Whole Blood

Facu

lty

Physical Sciences

Dep

artm

ent

Pure and Industrial Chemistry

Dat

e

December, 2007

Sign

atur

e

CONCENTRATIONS OF CADMIUM, LEAD AND CHROMIUM

IN HUMAN WHOLE BLOOD

OKENYI, CALISTER EKPERECHI

PG/MSc/05/40088

DEPARTMENT OF PURE AND INDUSTRIAL CHEMISTRY

FACULTY OF PHYSICAL SCIENCES

UNIVERSITY OF NIGERIA, NSUKKA

DECEMBER 2007

CONCENTRATIONS OF CADMIUM, LEAD AND CHROMIUM

IN HUMAN WHOLE BLOOD

OKENYI, CALISTER EKPERECHI

PG/MSc/O5/40088

DEPARTMENT OF PURE AND INDUSTRIAL CHEMISTRY

FACULTY OF PHYSICAL SCIENCES

UNIVERSITY OF NIGERIA, NSUKKA

DECEMBER 2007

) BEING A THESIS SUBMITTED IN PARTIAL FULFILLMENT

FOR THE AWARD OF MASTER OF SCIENCE DEGREE IN I

ENVIRONMENTAL CHEMISTRY.

CERTIFICATION

This research work on "Concentrations of Cadmium, Lead and Chromium

in tiurnan Whole Blood" is the original work of the author. I t has not been

presented to any organization or any body for academic award or the like except

to the Department Pure 2nd Industrial Chemistry of University of Nigeria,

Nsu kka.

All quotations are indicated and the sources of the information are

specially acknowiedged by means of references.

Dr. C.0.B QKOYE

SUPERVISOR-

Dr. C.0.B BKOYE

HEAD OF DEW.

DEDICATION

This research work is dedicated to those who contributed in different ways in

sanitizing our environments.

ACKNOWLEDGEMENT

My special gratitude goes to Almighty God who is the fountain-head of

knowicdge and the one that made it possible for me to have carried out this

research. My parents Late Mr. and Mrs. Kierian Okenyi are also remembered for r my procreation. Also my heart-felt gratitude goes to my project supervisor Dr.

C.0.B Okoye for his immense contributions towards the success of my research

work and the postgraciuate programme generally from its inception.

I am also very thankful to all the lecturei-s in the Department of Pure and

l~~dustr ial Chemistry U.N.IU who made my postgraduate programme a success.

Pioreover, I am indebted to my classn7ates eq~ecialiy Chidi mma Okpara for her

beiievolence to me during the period of our course works. I also appreciate the

efforts of some staff of Bishop Shanalian Hospital Nsukka, U.N.T.H. Enugu,

Eastern Nigeria Medical Centre, Enugu, and National Orthopaedic Hospital Enugu

fo'r their kindness to me during my period of sampling.

I wish all God's favour and protection.

Okenyi Calister Dept. of Pure & Ind Chem UNM. December 2087.

Abstract

Human whole blood samples obtained from blood banks in different hospitals in

Enugu State were analyzed for cadmium, lead and chromium concentrations

using atomic absorption spectrophotometric method. The results of the analysis

showed that about 72.7% of the samples had cadmium concentrations more

than the limit of safe exposure (5ug/l of blood). Also about 18.2% of the

samples had the concentrations of lead to be more than the maximum

permissible limit in adult human blood which is 300ug/l. On the other hand,

chromium concentrations in all the samples were within the range of its safe

exposure as it is a micro nutrient in man. The concentrations of cadmium and

lead could be indicative of both environmental and occupational exposure

hazards.

TABLE OF CONTENT3

Certification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....................... Dedication ... . . . . . . . . . . . . . . I I

Acknowledgement ............ .. .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Abstracts ............. .. ........... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv -- I ab!e o.i conterits .......................................................................................... v

List of tables ................................................................................................... vii

CHAPTER ONE

1.0 INTRODUCTION .......... .. ................................................ I 1 1 Environmental pollutariis ................................................................ 1

1.2 ..Trace met& in tiurnan Blood .......................................................... 2

3 Sources and effect of trace metals in humat-i blood ......................... 2

1.4 A iins m d objectives of this research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.5 Scope of the study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

CHAPTER TWO

2.0 LITERATURE REVIEW ......................................................... 6

2.2 . Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

E~ivironrnental Pollution ............ ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Blood ................................................................................................. 14

h'aernatotoxicity ................................................................................... 17

Storage Of Toxicants ............................................................................ 18

.................................... Cadmium, Lead And Chromium Occurrences 18

Heavy Metal Metabolisms I17 Man ....................................................... 19

............................................................... t-ieavy Metal Toxicity I n Man 22

Detoxification Of Heavy Metals In Man .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... 24

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cetection Of Heavy Metals 25

. . . . . . . . . . . . . . . . . i ieavy Netai Analysis Iri Biologicai Sz;-n$cs ;;sing A9.S 28

CHAPTER THREE

............... ........ 3. 0 EXPERIMENTAL ... b

............................................. 3.1 Sources and coliecticn of Lhe samples 31

........................................................ 3.2 Apparatus and equipment used 31

................................................................................. 3.3 Reagents used 32

............................................................... 3.4 Preparation of the samples 32

3.5 Preparation of the heavy metal stock solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

............................................................ 3.6 Determinations of the metals 33

........................................................................................... 3.7 Calculation 34

CHAPTER FOUR

..................................... ......... 4.0 RESULTS AND DISCUSSION .. 35

4.1 Resuks of the analysis .............................................................................. 35

............................................................................................ 4.2 3iseussion 36

LIST OF TABLES

Table 1: Natural Concentrations of some Heavy Metals

in Aquatic and Soil Environments -- -- -- -- 10

Table 2: Typical Concentrations of Some Heavy Metals in Humans -- 11

Table 3: Concentration Limits of some Heavy Metals in Human Tissues -- 24 . Table 4: Characteristic Wavelengths of some Metal Atoms -- -- 2 6

Table 5: Fuel/Oxidant Combination for Flame AAS -- -- - - 2 8

Table 6: Concentrations of Cadmium Lead and Chromium in

Human whole Blood -- -- -- -- -- -- 35

LIST O F FIGURE

Standard Calibration Curve for AAS Metal Determinations -- --- 33

CHAPTER ONE

1.0 INTRODUCTION

11 Environmental Pollutants

Human beings have significant impact on the environment especially now

that there has been much increase in human population. The increase in

population had led to corresponding increment in human activities like

industrialization, transportation, mining and agricultural processes which

generate different substances that can influence the environmental make ups

negatively. When these occur, our environment is said to be contaminated or

polluted.'

Environment can be defined as the place surrounding an organism. It

includes both biotic (living) and abiotic (non living) factors that affect the

organism in the surroundings. Land (lithosphere), water (hydrosphere), and air

(atmosphere) make up our environment and these serve as the buckets where

wastes are channeled or disposed.

Environmental pollution is the introduction of harmful substances or

toxicants into the environment thereby making it (environment) unsuitable for

both plants and animals living in it. It can be in form of land, water or air

pollution and some of the pollutants have cumulative effects in both plants and

animals. These effects depend on the biological chemical, and physical

characteristics, concentrations of the toxicant in the environment, and can lead

to either death, ill-health or both2.

1.2 Trace Metals in Human Blood

I n man, blood is one of the body fluids and serves as a medium for

toxicant distribution because it is connected to other tissues and organs in the

. body. The distribution of the toxicants occurs when they are ingested, inhaled or

absorbed through the skin. Human blood is made up of the solid cells or

corpuscles namely; red blood cells (erythrocytes), white blood cells (leucocytes),

and platelets (thrombocytes). The liquid portion of the blood where the cells are

suspended is called the plasma. Functions of blood include; distribution of

oxygen carrying pigment called haemoglobin, protection of the body against the

invasion of micro-organisms, formation of blood clots to prevent excessive blood

loss when injury occurs and so on. Other substances found in blood are mineral

salts, food materials, hormones etc. An adult man contains about 5.5 litres of

blood and this constitute about 7% of the total body eight.^

P.3 Sources and Effects of Trace Metals in Human Blood

Haematotoxicity is the state of blood contamination as a result of the

presence of toxicant(s) in it. This state of blood affects its quality or quantity

produced in the bone marrow. I t can be linked to malfunctioning of other tissues

like kidney, liver, lung, bone, and the peripheral and central nervous systems etc.

1

Heavy metals are those metals that have their densities to be more than

5g/cm3. They include; cadmium, lead, chronlium, mercury, arsenic, tin and so

on4. Some of them like cadmium, lead, arsenic and mercury are considered toxic

in man no mater their concentrations5. They are also called trace elements

because their concentrations in the natural environment are low. Among these

elements, some are called essential elements in man because they are needed in

small quantities for different metabolic processes in the body e.g. chromium,

copper, zinc, iron, selenium etc.

The earth's crust is the major source of cadmium, lead and chromium of

the various environmental systems. The rocks that form the soils were initially

subjected to various physical and chemical processes like erosion weathering.

Subsequently, soils and sediments became the terrestrial and aquatic substratum

for plants which absorbed, translocate and in some cases bioaccumulate some of

these elements. These lead to the incorporation of these elements in man and

other animals when they consume the plants.

Water gets contaminated with heavy metals through natural weathering

and leaching, and by dissolving and reacting with them. I t also mobilizes and

distributes them to different sites. Volcanic activity, forest fire, soil dusts and salt

sprays bring about both aerosols and particulates which are the major sources of

the metals to the atmosphere5. Some quantity of these elements in the

atmosphere can deposit on the plants, soil, water or can be inhaled directly by

human beings and other animals thereby increasing the concentrations of the

metals in the body.

As the effects of cadmium, lead and chromium are cumulative, they

accumulate in target organs and soft tissues like kidney and liver thereby causing

4

some impairment in the functioning of these organs. This is made possible

because of a protein called metallothionein found i

and lead bind to very strongly.

More concentrations of cadmium are found

liver while liver accuinulate most of the lead than

in soft tissues which cadmium

in the kidney followed by the

the other soft tissues. Equal

concentrations of chromium are obtained in kidney, liver and blood.

1.4 AIMS AND OBJECTIVES OF THIS PROJECT

This research is aimed at evaluating the extent of environmental pollution

by heavy metals in Nigeria. It is meant to ascertain quantitatively the

concentrations of cadmium, lead and chromium in the blood of adult Nigerians as

a result of their exposures to different environmental and occupational hazards.

Besides it is expected to serve as an eye-opener on environmental

degradation and will go a long way in enlightening the general public on the

importance of keeping good environment. This will inculcate good habits of

proper waste disposals in individuals. It is also targeted at making people

understand the problems associated with heavy metals and will help the public in

protecting themselves against the sources of these metals in order to reduce

pre-mature death and ill-health.

1.5 SCOPE OF THE STUDY

The scope of this study is quantitative determination of the concentrations

of cadmium, lead and chromium in human whole blood of adult Nigerians. The

modes of administrations, rates of accumulations, sources and speciations of

these metals in the blood samples are not included.

CHAPTER TWO

2.0 LITERATURE REVIEW

2.1 ENVIRONMENT

The natural environment is the place surrounding an organism. It

comprises of living and non-living things that occur naturally on the earth or

some part of it. It is made of the following components:

a. Complete landscape unit that functions as a natural system without

massive human intervention e.g. all plants, animals, rocks, and natural

phenomena that occur within their boundaries.

b. Universal natural resources and physical phenomena lacking clear-cut

boundaries e.g. air, water, climate, radiation, electric charge and magnetism not

from emanating human activity.

c. Natural features, which occur within the area heavily influenced by man

e.g: wild birds in urban areasI2

A geographical area is regarded as a natural environment if human impact

on it is kept under a certain limited level. On,the other hand, built environment,

which comprises of the areas and components that are heavily influenced by

man is not actually a natural en~ironment.~

2.2 ENVIRONMENTAL POLLUTION

This is the introduction of dangerous or harmful substances into the

environment which render it unsafe for both plants and animals found in it.6

These substances are called pollutants and may be in the form of chemicals,

noise, heat, energy, particles and so on. hey have deleterious effects which

endanger human health, harm living resources and ecosystem and impair or

interfere with amenities and other legitimate use of environment.

2.2.1 Forms of Environmental Pollution

The major forms of pollution to the environment include

a. Air pollution: This involves the release of chemicals and particulates

into the atmosphere. Common examples of air pollutants are carbon (11)

oxide (CO), sulphur (IV) Oxide (SOz), chloroflurocarbons (CFCs), and

nitrogen (IV) oxides produced by industries and motor vehicles.

Photochemical ozone and smog are created as nitrogen and

hydrocarbons react with sun~ight.~

b. Water pollution: This occurs through runoff, leaching, liquid spills,

wastewater discharge, eutrophication and littering.

c. Soil or land pollution: I n some cases, chemicals are released by spill

or underground storage tanks leakage causing soil contamination.

Among the most significant soil pollutants are hydrocarbons, heavy

metals, herbicides, pesticides, chlorinated hydrocarbons and methyl-tert-

butylether (MTBE).

d. Radioactive pollution: Radioisotopes are radioactive forms of

chemical elements. The nuclei of their atoms radiate or emit particles

and rays during the process of radioactive decay and di~tingeration.~

Each radioisotope has half-life (length of time required for the number of

the atoms in a sample of that isotope to decay to half the original

con~entration)~.

e. Noise pollution: It encompasses roadway noise, air-craft-noise,

industrial noise, as well as high intensity sonar.'

f. Light pollution: This comes from light trespass, over-illumination and

astronomical interference.

g . Thermal pollution: Sometimes, the human influence may cause a

change in the temperature of natural water b ~ d i e s . ~

h. Visual pollution: This form of pollution refers to the presence of

overhead power lines, motorway bill boards, scarred of trash or municipal

solid wates.'

2.2.2 Sources of Environmental Pollution

I n air pollution, motor vehicle emissions are the leading causes. Principal

stationary pollution sources include chemical plants, coalfired power plants, oil

refineries, petrochemical plants, nuclear waste disposal activity and incinerators.

Others include large livestock farms, polyvinyl chloride (PVC), metal production,

plastic factories and other heavy industriesm5

Some of the most soil contaminants are hydrocarbons, heavy metal e.g.

chromium and cadmium found in rechargeable batteries, lead found in paint,

aviation fuel and gasoline. Other contaminants include methyl-tert-butylether

(MTBE), zinc, arsenic and benzene. Ordinary municipal landfills are the sources

of many chemical substances entering the soil environment, emanating from the

wide variety of refuse.

Moreover, pollution can occur as a result of natural disaster like hurricane

which causes water contamination from sewage and petrochemical spills from

boats or automobiles. Nuclear power plants or oil tankers can produce

widespread and potentially hazard-oil chemicals released when accidents occur.'

The dominant source of noise pollution are motor vehicles and airplanesg

2.2.3 Environmental Pollution by Heavy metals

Some metals are regarded as heavy metals because their densities are

more than 5 g ~ m - ~ . Typical examples include lead, cadmium, mercury, arsenic,

chromium, nickel, zinc, copper etc. Among these, some are called essential

elements because they are needed in small quantities in both plants and animals

for different metabolic processes. These include zinc, copper, chromium etc.

Their deficiencies in an organism may cause deficiency syndrome and

abnormalities. Other heavy metals are classified as toxic elements because they

- do not perform any useful function in an organism rather they pose some

significant prob~ems.~

' 2.2.4 Interaction of heavy metals with the environment

All the trace elements have their primary origins from the earth's crust

which is made up of rocks. These rocks form the soil and sediment layers by

undergoing some physical and chemical processes like erosion weathering. The

soil and sediments subsequently became the terrestrial and aquatic substratum

for plants which absorbed, translocated, and in some cases biaccumulated these

elements. I n the food chain, when animals consume the edible parts of the

plants, these elements become incorporated into their bodies.''

Water on the other hand is a natural source of heavy metals. This is made

possible when rock undergoes natural weathering and leaching processes, and

by dissolving and reacting with materials, mobilizes and distributes the metals.

Volcanic activity, forest fires, oil dusts and salt sprays contribute both

aerosol and particulate of these metals in the a tm~sphere.~~. . Table 1 shows

~a tu ra l concentrations of some heavy metals in aquatic and soil environments5.

Metal

Cadmium

Zinc r-

Freshwater (us/ 1) 0.03

- - -

Concentration

As the geological and biological alteration of the earth's surface are slow, man'

input to heavy metal composition of the biosphere has been drastic, resulting in

widespread heavy metals' changes in environmental, biological and marine

systems.

The heavy metal contents in animal or body fluids are dependent on the

metal(s) content and bioavailability in the soil or sediment-plant-animal-human

food chain1'. Some common components of food in given diet can affect both

amount of the metals and their chemical forms. These accumulate in different

parts of the organism. Table 2 shows typical concentrations of some heavy

metals in humans5.

I Concentrations (uglg) dry weight

Cadmium 1 15 1 0.8 1 0.2 11 10.1

Kidney Hair Liver

Lead

Chromium

Mercury

Environmental pollution also occurs, when there is increase in the

concentrations of the heavy metals with respect to their natural concentrations in

the environmenf. Their increased concentrations are attributed to different

Arsenic --

Copper

Zinc

Milk

3

0.1

0.1

Blood

0.01

14

150

5

0.1

0.1

0.03

20

250

1 '

0.8

0.1

0.1

2 0

180

10

1.5

0.5

3

0.1

0.7

0.5

280

1500

1

1000

900.

anthropogenic activities like transportation, industrialization, mining, agricultural

practices and domestic activities.

2.2.5 Sources of heavy metals in the environment

Heavy metals sources to the atmosphere include coal and fuel power

generation plants, metal processing and smelting, transportation, combustion,

waste incineration and aerosol sprays (halocarbons). The major industrial

emissions are non-ferrous metal smelters, petroleum refining, cement

production, chloro-alkali production, aluminum smelters, petroleum refining and

chemical productions. The presence of small particulates of these metals in the

air poses global environmental pollution". These particles eventually descend on

vegetation and soil surfaces through brownian motion, sedimentation, impaction

and interception.

Mining and ore processing, coal and fuel combustion, industrial

*processing, agricultural (fertilizer, pesticides, and herbicides), domestic and

agricultural effluents are the major sources of heavy metal in natural water

bodies. Others are transportational (urban and motorway run-off), and nuclear

activity. They can also come from atmospheric fallout, leaching or dumping from

the lithosphere, or direct into the water bodies. The element concentrations of

these metals in water depends on magnitude of the input, duration of the input,

physical and chemical form of it etc. Some heavy metals undergo bio-

amplification or bio-transformation by plankton and bacteria respectively in water

bodies. Mercury, arsenic, tin, and lead undergo biomethylation in water sediment

interface, leading to the production of more toxic species which are concentrated

in shellfish.12

I n Nigeria, some researches carried out showed high concentrations of

some heavy metals (Cd, Fe, Mn, Ni, Zn, Pb, Co, Cu, Cr) in sediments from the

Lagos ~ a g o n ' ~ . Also the concentrations of Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb and Zn

were high in some fish and shellfish from the lagoon when compared to others

from rural rivers14. Analysis of some heavy metal concentrations in dried fish

from Nigerian markets revealed an enrichment of the metals in some of the fish

especially the ones from Lagos, Ilorin and Kano markets1'. The high

concentrations in the water bodies and fish are attributed to some of the sources

of these metals mentioned above.

Sources of heavy metals to the soil include metal smelting, chemical

process factories, coal and fuel, combustion plants, alongside motorways,

dsmestic and industrial waste incinerators. Different agricultural practices like

fertilizer, pesticides, sewage sludge and wastewater irrigation can also add these

metals to the soil.'

Plants can accumulate heavy metals from the soil, water and air thereby

becoming elemental sources for animals and man. The elemental absorption by

plants' root depends on the quantity and chemical form of the element present,

soil pH, moisture, aeration, temperature etc. Tobacco is a special food crop with

an unusual propinquity for bioaccumulation of Cd from the soil. Most times, the

accumulation of the heavy metals affects the metabolic processes in the plantslO.

However, analysis carried on the concentrations of some trace metals in some

Nigerian baked products showed low concentration of them in the products?

Besides other animals can serve as the source of heavy metals to man

when the later consumes the former. Although some of the metals are essential,

their concentrations more than the limit of safe exposure can lead to health

problems. Lead and cadmium concentrations were found to be above the

maximum permissible levels in meat samples obtained from different parts of the

country1'. These indicate that there is gradual contamination of our environment.

2.3 BLOOD

About 7-8% of human body weight is from blood. I t is an essential fluid

that carries out critical functions of oxygen and nutrient transportation to cells,

. as well as getting rid of carbon dioxide and other waste products from the body.

I t also plays a vital role in our immune system and in maintaining a relatively

constant body temperature. Human whole blood consists of different

components namely; red blood cells, white blood cells, platelets and plasma3.

2.3.1 Red Blood Cells ( ~ r ~ t h r o c ~ t e s )

These are relatively large microscopic cells without nuclei. They are similar

to the primitive prokaryotic cells of bacteria. They are biconcave disc with an

average diameter and their relative excess of surface over volume makes them

very deformable. These cells normally make up 40-50% of the blood volume.

They transport oxygen from the lungs to all living tissues of the body and carry

away carbon dioxide. Red cells are produced continuously in the bone marrow

from stem cells at about 2-3 million cells per second and they have life span of

about 120 days. The main contents are haemoglobin, variety of enzymes and

metabolic intermediates which are essential for the proper functioning of the

haemoglobin and for maintaining the integrity of the cel~s. '~

Haemoglobins are tetramer consisting of two y-and two non 7-globin

chains each with its own iron containing haem group. It makes up to 95% of a

red cell and performs the function of oxygen transportation. Each red cell has

about 270 million iron rich haemoglobin molecules.

When the cells are degraded by the reticulo-endothelial systems in the

spleen, the porphyrins of the haem portion of the haemoglobin are broken down

to bilirubin. The iron is released and transported to the bone marrow where it is

either incorporated into newly synthesized haem or stored in the reticulo-

endothelial cells as ferritin or haemosiderin. The globin peptide chains are

hydrolysed and their constituent amino acids re-enter the general metabolic

poollg. The bilirubin is excreted in the bile. People who are anaemic generally

have a deficiency in red blood cells. The red colour of the blood is primarily due

to oxygenated red cells.

2.3.2 White blood cells (Leucocytes)

White blood cells exist in variable numbers and types but make up a very

small part of blood's volume normally only about 1%. They occur elsewhere in

the body as well, most notably in the spleen, liver, and lymph glands. Most of

these cells are produced in the bone marrow while others are produced in the

thymus gland, which is at the base of the neck. The white cells called

lymphocytes are the first responders for our immune system. They seek out,

identify, and bind to alien protein or bacteria, virus, and fungi so that they can

be removed. Other white cells called granulocytes and macrophages then arrive

to surround and destroy the alien cells. They also have the function of getting rid

of dead or dying blood cells as well as foreign matters like dust and asbestors18.

White blood cells last for about 18-36 hours before they are removed although

some types live as much as a year. There are actually many specialized sub -

types of white cells but all participate in body defence mechanismlg.

2.3.3 Platelets (Thrombocytes)

They are cell fragments without nuclei that release blood clotting

chemicals at the sites of wounds. They do this by adhering to the walls of blood

vessels thereby plugging the rupture in the vascular walls.

There are more than a dozen types of blood clotting factors and platelets

that need to interact in the blood clotting process. Recent research has shown

that these platelets fight infections by releasing protein that kills the invading

bacteria and other micro-organisms. Also, the platelets stimulate the immune

system. They have a lifespan of 9-10 days and are about 113 the size of red

cells. They are also produced in bone marrow from stem cells20.

2.3.4 Plasma

Plasma is the non-cellular fraction of anti-coagulated blood. I t is the

relatively clear or yellow liquid water containing sugar, fats, protein and salt

solution which carries the red, and white cells, platelets and other chemicals.

About 95% of it is water. Plasma brings nutrients to different cells throughout

the body when the heart pumps the blood. I t also removes the waste products of

metabolism. Besides, plasma contains blood clotting factors, sugai-, lipids

vitamins, minerals, hormones, enzymes, antibodies and other proteins. Human

adult has a blood volume of roughly 5 litresZO *

2.4 HAEMATOTOXICIN

Apart from nutrients and waste products, some toxicants or poisons can

enter the body and get distributed by the blood to different organs and tissues

like kidney, liver, lung, heart and spleen etc. The factors that determine the rate

of. toxicant distribution include duration of exposure, dose, physical and chemical

nature of the toxicant, routes of administration, presence of lymphatic or blood

vascular components and volume of the toxicant etc.'

When there is presence of toxicants in the blood the quality and quantity

'

of the blood produced may be affected leading to impairment in the normal

functioning of the blood. This state of blood poisoning can be linked to the toxic

effects in the kidney, liver, skin, respiratory system, and central nervous and

peripheral nervous systems.

18 .

2.5 STORAGE OF TOXICANTS

Common storage locations for toxicants in humans include liver, kidney,

bone, lung, circulating plasma protein and fats2'. The kidney has he highest

blood flow/mass ratio (420m1/100g) of all the organs in the body. This is more

than four times greater than that of the heart muscles. This large volume of

blood exposes the organ to toxicants1.

Besides, liver is good for concentrating toxicants. This is because it has a

large blood flow/mass ratio. It receives the largest percentage of cardiac output

(27.8%). It is also the site where most toxicants undergo biotransformation

(process by which substances are changed from hydrophobic to hydrophilic

molecules to facilitate elimination form the body). Substances like lead and

strontium can substitute calcium ion in the bone. Fluoride may also be displaced

by hydroxyl ion and become incorporated into the bone matrix. Some poisons

can can be stored in albumin (plasma protein) and fat.'

- 2.6 CADMIUM, LEAD AND CHROMIUM OCCURENCES

Cadmium-containing ores are rare and when found, occur in small

quantities. Greenockite (CdS), the only cadmium mineral of importance, is nearly

always associated with sphalerite ( z ~ s ) ~ . CdS is released into the environment

naturally through volcanic actions. Other sources to the environment include

ocean sprays, and forest fires etc. Naturally occurring Cd is composed of 8

isotopes of which two of them show natural rad i~act iv i ty~~.

Lead is present at about 20ppm in the earth's crust and the medium of its

transport in the air are fine particulates ( 4 u m diameter). The residence time

for the particulates in the air is from several hours to several days. These

particles most often deposit on soil, get retained and eventually become mixed

into the surface layer and may be taken up directly by grazing animals and

micro-organisms22.

Chromium occurs in nature mostly as chrome iron ore (FeO. ~ r ~ 0 ~ ) ~ ~ . Its

concentration in the earth's crust is about 60ppb.

2.7 HEAVY METAL METABOLISM I N MAN

Cadmium is not essential in human and animal nutrition. Its

gastrointestinal absorption in humans is between 3-8010~~. The dietary level of

zinc and the solubility of cadmium salts influence this percentage. The absorption

of cadmium ions from the site of parenteral injection in the blood is rapid and

complete. Cadmium ion penetrates erythrocytes and gets distributed in the

blood. I t also binds to serum protein especially a-globulin and is readily

distributed to other tissues.25 Cadmium absorption through the skin is 'low but

absorption through the lungs during inhalation of its mist or aerosols from

tobacco smoking is fast and complete; only'the insoluble CdS remains in the

lungs unabsorbed thereby causing local inflammation and u~ceration*~. Greater

portion of the absorbed Cd is retained in the kidney, liver, reproductive systems

and lungs, but pancrease, aorta, oesephagus and omentum also accumulate Cd

under certain conditions, The reason for its retention in the soft tissues is

because of the presence of metallothionein in them for which cadmium has high

affinity for.

Excretion of Cd in mammals is slow and is predominantly faecal although

some quantity can also be removed in urine. The accumulation of it in humans

increases with age, with its level in kidney, liver and lungs increasing for

example, it is not detected in new borne babies but could be detected at 10

months of age2?

Inorganic forms of lead are absorbed through ingestion or inhalation

whereas organic Pb salts are absorbed through the skin. Only 10% of an

ingested dose of Pb is absorbed in adults but absorption in children may be up to

5 0 % ~ ~ . The absorption of Pb is enhanced by deficiencies of iron, calcium, and

zinc28. Under certain conditions, Pb is absorbed and stored in several body

compartments. About 5-10% of the absorbed Pb is found in blood, most of which

is. located in erythrocytes, hydroapatite crystals, where it is exchanged with the

blood. Inhaled Pb is absorbed more rapidly (about 90%) than by any other

route; lungs and the respiratory tract including nasal passages absorb Pb. About

40% of inhaled Pb gets trapped in the upper respiratory tract.

Intravenously administered Pb is distributed mostly in liver and bone,

while ingested one is distributed thus; bone (6O0/0), liver (25%), kidney (4%),

reticuloendothelial system (3%), intestinal walls (3%) and others (traces)26. Its

retention in mammalian skeleton is as follows; liver>

kidney>aorta>muscles> brain. I t can permeate the placental barrier and can be

found in milk.

Generally, excretion of Pb is slow with an estimated biological half-life (in

soft tissues) of 24-40days. The remainder of the stored Pb is found in some soft

tissues notably kidney and brain. The primary route of excretion is through

faeces (80-9O0/0). To a lesser extent, it is excreted through sweat and milk2'.

Tetraethyl lead (TEL) is readily absorbed from digestive, respiratory tracts

and skin due to its solubility in lipids and its diffusibility. Major portion of

absorbed TEL accumulates in the brain due to the special affinity of the organic

Pb to lipids in the nerve tissues26.

Chromium is essential in many aspects of animal life. It is an essential

component of the glucose tolerance factors2': Its requirement in normal human

adult is about 50ug and the average daily intake varies from 60-lOOug, This

represents about 5% of the total body contents, and there is a wide margin of

safety?

Gastrointestinal absorption of chromium ion is very low, less than 3%

regardless of nutritional status and dosage3'. The acidic value of the stomach

keeps it in trivalent form (cr3+) and reduces cr6+ to c?+ and the absorption of

c?+ from the stomach is negligible. Oxalates enhances this absorption while

phylates inhibit i t 2G. Intravenously administered cr3' salts and soluble form of

cr3+ absorbed from the alimentary tract into the blood bind progressively to

siderophilin, transferring albumins and y-globulin. Intravenously administered

cr6+ (chromates and dichromates) in physiological doses permeates the

erythrocyte membrane and is sequestered.

2.8 HEAW METAL TOXICITY I N MAN

Cadmium is a potential environmental hazard and is toxic in humans but

this depends on its dose and nature of its salt ingested. It induces depletion of

iron in liver causing anaemia due to lack of absorption of iron from the intestine.

I t also causes poor mineralization of vitamin D and absorption of calcium into the

bones leading to softening of the bones or osteomalacia". Besides cadmium

increases the retention of sodium ion in the kidney which leads to

hypertension32. Other symptoms of Cd toxicity are retardation in growth,

sterilization in sexes, tumour formation and tetratogenic effects (abnormal

structure) in children. Inhalation of dust Cd compound causes unnatural

distention and rupture of the air vesicles of the lungs (pulmonary emphysemia).

This is characterized by shortness of breath and bronchitis and so on.

Lead toxicity in man depends on the level of diffusibility and its

concentrations in soft tissues such as liver, kidney, and brain, than its total

concentration in the body33. Pb poisoning is cumulative in that its toxic symptoms

are not immediately seen after oral intake of a toxic dose, making it difficult to

assess the lethal doses2!

The major health effects of Pb manifest in three organ systems namely;

haematological, central nervous and renal systems. Its acute poisoning

symptoms include tiredness, vomiting, uncoordinated body movement,

convulsion, stupor, coma and death. Chronic toxicity systems are anaemia, brain

damage and general intellectual and psychological i m ~ a i r m e n t ~ ~ .

The effect of Pb on haematopoietic system are abnormal circulation of

erythrocytes, impairment of the production of haemoglobin and stimulation of

erythropoiesis in the marrow. This leads to morphological changes which cause

increased production of abnormal red cells, basophilic cells with nuclear

abnormalities and inadequate haemoglobin. Pb toxicity in central and peripheral

nervous systems affects the cerebellum, spinal cord, motor and sensory nerves.

Pb kncephalopathy is a disease of neonatal man and animal caused by transfer 1

of Pb through the maternal milk, the mothers are ~ n a f f e c t e d ~ ~ . Children are . P t , ~ ; l d r W A t t ~

more prone to central nervous dysfunction than adults. $3 %+ ,%,- F..#- -

Chromium poisoning in humans is caused by accidental ingestion of

chromates. cr3+ is one of the least toxic of the trace metals34. The cr6+ is more

toxic than c?+. cr6' is topically corrosive and its oral ingestion is toxic despite

the ability of the organism to reduce it to less toxic c?'. Accidental swallowing of

dichromates causes gastrointestinal ulceration and symptoms affecting the

central nervous system. Inhalation of cr6' compounds can cause injury to the

nasal mucosa leading to inflammation and ulceration. The larynx is also affected.

Chromium compounds are not carcinogenic when taken orally but

epidemiologic evidence implicates fine particles of Cr salts in pulmonary cancer35.

cr6' is an established human carcinogen. Table 3 shows the concentration limit

of some heavy metals in human tissues35.

Metal

Cadmium (blood)

urine

Lead (children blood)

adult blood

Mercury (blood)

(urine)

Arsenic (whole blood)

Serum/Plasma

Urine

Hair & nai (ug/g)

Normal concentration I Conc associated with Or less than (ug/l) serious toxicity (ug/l) 5 2 0

2.9 DETOXIFICATION OF HEAVY METALS I N MAN

High dietary intake of zinc, copper and iron in more than adequate

quantities increase the formation of metallothionein in kidney and liver thereby

reducing the toxicity of cadmium in man. Ascorbic acid, cystein, glutathione and

selenium in the body have some ameliorative effects on Cd toxicity by reducing

. Cd absorption in the body37.

Also dietary intake of calcium, iron, zinc, copper and phosphorus reduce

Pb absorption and retention in the body by making the parathyroid hormone

increase the urinary excretion of Pb. Zinc reduces its distribution, increases the

formation of metallothioneine content of the liver and kidney and increases Pb

binding to this protein3'. Pb shows high affinity for the sulfhydryl groups of

methallothioneine.

There is no specific mechanism by which chromium can be removed from

living systems but a possible detoxification of it can be the increased formation

of ribonucleoprotein in the liver3g.

. 2.10 DETECTION OF HEAVY METALS

The techniques required for analyzing heavy metals in samples must offer

low detection limits, wide linear dynamic range, simple interference free data and

qualitative, semi quantitative and quantitative analysis. Others include possible

simultaneous multi-element capacity, simple sample preparation and high

throughput and low cost per determination. The methods that can be employed

in analyzing heavy metals are atomic absorption spectrometry (flame and

electrothermal), atomic fluorescence spectrometry, inductively coupled plasma .

optical, neutron activation analysis, x-ray fluorescence etc.

2.10.1 ATOMIC ABSORPTION SPECTROPHOTOMETRY (AAS) PRINCIPLES

This is an instrumental method of analysis that measures the intensity of

absorbed light when a sample is aspirated into a flame4'. Light beam is directed

through flame into a monochromator (wave-length selector) and then into a

detector that measures the intensity of light absorbed based on Beer-Lambert

law of absorption, which states that the amount of light absorbed in a solution of

low concentration is directly proportional to the absorbing atoms irrespective of

the intensity of the light source40. This method of analysis is sensitive and

depends upon the presence of free unexcited atoms. Each metal has its own

characteristic absorption wavelength, a source lamp made up of that element

and these make the method relatively free of spectral interferences. Table 4

shows the characteristic wavelengths of some metal atoms4.

Metal

Chromium / 357.9

Wavelengths (nm)

Cadmium

Lead

228.8

283.3

Mercury

2.10.2 Interferences in AAS determination

This generally occurs when there is unabsorption due to atoms that are

bound in molecular combination in the flame. It can occur when the flame is not

hot enough to dissociate the molecules. It' can also result from immediate

oxidation to a compound of dissociated atoms5.

476.0

Copper

2.10.3 Instrumental requirements for AAS

The basic ones are

Light source

Sampling unit

Wavelength selector or monochomator

324.7

Detector

Readout device

Hollow cathode lamp (HCL) is a device used for producing radiation with

the necessary characteristics. I t is made up of a glass envelope containing anode

and cathode electrodes. The cathode is either made from the analyte or packed

with a non-volatile form of it. On striking the cathode (sputtering), atoms of the

cathode material are ionized and volatilized. On relaxation, radiation with the

appropriate sharpline characteristic is produced.

The components of the sampling unit are nebulizer, spray chamber and

the burner. The nebulizer is used for the appropriate proportioning of the fuel

and support gasses and in breaking of the solution into fine vapour, liquid,

aerosol or mist. The burner on its part receives the mist, converting it into

unexcited state by evaporating the solvent followed by decomposition of the

molecules. Table 5 shows the fuel/oxidant combination for flame A A S ~ .

Cadmium

Lead

Chromium

Mercury , -. - - .. - -- Copper

Zinc

Aluminum

Fuel and oxidant combination

Air-Acetylene

Air-Acetylene

Air-Acetylene

Air-Acetylene

Nitrogen 1 oxide-Acetylene

Wavelength selector or monochromator is used to isolate light of narrow

bandwith. It may be made of quartz prism or gratings. The later consists of a

glass or shining metal sheets with equidistant drawn lines and can resolve light

better than the quartz prism. The detector is made of a photoelectric cell and

can convert light signal reaching it into electric current. Types of photoelectric

cells are barrier layer and photomultiplier cells. Read-out device is used to bring

out the result or output of the analysis .it can be meter, chart recorder, digital

display system or computer connected to printer4!

2.11 HEAW METAL ANALYSIS I N BIOLOICAL SAMPLES USING AAS

2 1 1 . 1 Sampling

Carefulness is needed for sampling of biological tissue and fluids. The

nature of the proposed analysis determines the type of the sample to be

collected. When human being is concerned, it may be required from neonatal,

postnatal, children, adult, pregnant or in some cases from chronic disorder

patients. The tissues or fluid that can be sampled include scalp hair, urine, blood,

and nail.

. Samples are to be collected with clean and sterile material in order to

prevent contamination. Stainless steel blades, biopsy needles, metal scissors or

tweezer are to be avoided if the analysis is for metals. Blood samples are to be

taken using Teflon or polyethylene catheters. Urine requires mid-stream samples

to be put into a covered acid washed polyethylene container. Animal organs

should be collected with a quartz or tantalum blade5.

2.11.2 Sample preparation

The method of sample preparation to be used should be one devoid of

contamination of the sample. Hair sample require ultrasonication with 0.1%

tritonTm ~ 1 0 0 , filtration, washing with methanol and repeated double -distilled

deionised water. Blood, urine, milk and tissue sample may require dry freezing

before digestion.

2.11.3 Dry Ashing

Muffle ashing occurs at 500-550% and can decompose most organic matter. The

problem associated with dry ashing is that it may lead to volatilization of

mercury, arsenic, tin, selenium, lead, nickel and chromium in the sample

although this problem can be reduced by adding an ashing aid like concentrated

nitric acid. On the other hand, this method is always simple and convenient.

2.11.4 Wet Digestion

This method is always preferred for biological tissues and blood. This is

because much of the elements components of the sample are not lost through

vapourization. The mineral acids that can be used include perchloric acid, nitric-

hydrofluoric acid mixtures. (1 : l HN03/HF), nitric acid and hydrogen peroxide,

aqua regia etc. Biological tissues and fluids can be digested in Kjeldahl digestion

vessels, with controlled temperature heating mantle. Digestion in open vessel

may lead to volatility of some element but it can be controlled using pressurized

decomposition with nitric acid in Teflon digestion bombs. .

2.11.5 Precautions needed in wet digestion

i . Digestion of very fine powdered samples must be restricted to less than

50mg of samples, and only a maximum of 2ml of H N 0 3 should be added.

ii. Avoiding the digestion of biological materials containing more than 20% fat

content.

iii Digestion of organic material generate large amount of vapour, therefore

'

carefulness is needed and warm vessels should not be opened.

Wet digestion limitation is that it is slow, labour intensive, and

requires strict carefulness by the analyst"

CHAPTER THREE

3.0 EXPERIMENTAL

3.1 SOURCES AND COLLECTION OF THE SAMPLES

Whole human blood samples were obtained from different blood banks in

Enugu state. Samples 1-5 were obtained from the University of Nigeria Teaching

Hospital (UNTH) ltuku - Ozalla, Enugu; samples 6 and 7 were from Eastern

Nigeria Medical Centre, Enugu; samples 8, 9 and 10 were from the National

Orthopaedic Hospital, Enugu; and sample 11 was from Bishop Shanahan Hospital

Nsukka. Each sample contained little quantity of citrate phosphate dextrose

adenine solution which served as the anticoagulant.

3.2 APPARATUS AND EQUIPMENT USED

i Syringe (10 ml capacity )

ii. Evaporating dishes / crucibles

iii: Electric heater

iv. Tongs

v. Electric oven

vi. Muffle furnace

. vii. Beakers

viii. Standard flasks (25 ml capacity)

ix. Atomic absorption spectrophotometer, Model Pye Unican sp 1900.

3.3 REAGENTS USED

i Hydrochloric acid (BDH AnalaR grade)

i. Nitric acid (BDH AnalaR grade)

iii. Stock and standard solutions of cadmium, lead and chromium.

iv. Distilled - deionized water.

3.4 PREPARATION OF SAMPLES (ASHING)

1Oml of each of the samples were drawn into a clean and dry evaporating

dish using a 1Oml capacity syringe. The samples in the evaporating dishes were

heated to dryness using an electric heater. This was followed by addition of l m l

conc nitric acid to each of the samples to serve as an ashing aid. After a little

while, these acidified samples were re-heated in the fume cupboard until they

started charring. The samples were loaded into a muffle furnace and were

allowed to ash at 500°C for four hours. The dishes with their contents were

allowed to cool in the furnace before removing them. Each of the resulting

sample ash was dissolved in aqueous 1M HCI solution, and made up to 25mI with

distilled - deionized water using a 25ml standard flask. These were used for the

AAS analysis.

3.5 PREPARATION OF HEAVY METALS STOCK SOLUTIONS

a 1.63099 of cadmium chloride CdCI2 was dissolved in distilled-deionized

water and made up to 1 litre to give 1000 ppm of cadmium solution.

b 1.59859 of lead nitrate Pb(N03)2 was dissolved in distilled-deionized water

and made up to 1 litre mark to give 1000ppm of lead solution ,

c 2.82859 of anhydrous potassium heptachromate (K2 Cr2 O7 ) was dissolved

in distilled-deionized water and made up to 1 litre mark to give 1000ppm

of chromium solution .

Each of these stock solutions was diluted to obtain the working standard .

solutions of cadmium, lead and chromium which were used for the AAS analysis.

3.6 DETERMINATION OF THE METALS

A Pye Unican Sp 1900 atomic absorption spectrophotometer (AAS) was

used. The hollow cathode lamp for the metal to be analysed was installed and

aligned. The wavelength was set according to the user's manual for the metal to

be analysed (see table 4). The flame was put on and the flow rates of the fuel

(acetylene) and oxidant (air) were regulated accordingly to optimize the flame.

The burner was adjusted for stability and maximum absorption.

The standard solutions were run and their concentrations against

absorbances were plotted as in figure 1 b,elow to check for linearity. Each

standard solution was run three times to check for accuracy and precision.

Fig 1: A standard calibration curve

Metal concentration

Afterwards, blank was run to check instrumental drift or contamination followed

by the aspiration of each sample into the flame. The concentrations of the

analytes in each sample were obtained from the instrument directly.

3.7 CALCULATION

Each of the concentrations of sample obtained from the instrument was

multiplied by the dilution factor which was 2.5 to get the actual concentrations of

the metals in 1 litre of blood sample.

CHAPTER FOUR

4.0 RESULTS AND DISCUSSION

4.1 RESULTS

Table 6 below shows the results of the analysis on the concentrations of

cadmium, lead and chromium in human whole blood samples.

Table 6 Concentrations of cadmium, lead and chromium in .human

whole blood (pg/l).

Note: B.D.L = Below detection limit.

Sample No Concentrations in pg/l' blood I ~d I ~b ~r

4.2 DISCUSSION

From Table 6, all except samples 3, 7 and 10 have concentrations of

cadmium more than the limit of safe exposure which is 5 u g / 1 ~ ~ . This suggests

that the donors of these blood samples were exposed to cadmium sources like

smoking, cadmium containing diets, water, and cadmium compounds. The

cadmium may also had found its way into the donors by ingestion and inhalation.

The effect of Cd toxicity is cumulative as its half- life is more than 10

years25. Cadmium toxicity causes kidney, liver, reproductive organ, and lung

dysfunctions as these are the major organs of, accumulation. This is as a result of

the metallothionein found in them for which cadmium has high affinity33. Other

effects of cadmium poisoning are hypertension, osteomalacia, cancer and

teratogenic effects in women2?

Nevertheless, cadmium detoxication can be enhanced by dietary intake of

zinc, copper and iron38. Also ascorbic acid, vitamin D, cystein, glutathione and

selenium have ameliorative effects on cadmium toxicity. Chelating agents like

edetate calcium disodium (CaNa-EDTA) can be used to eliminate Cd from the

body since it can form Cd complex which can be removed through urine.

The concentrations of lead in samples 5, and 9 were found to be more

than the maximum permissible limit in adult which is 300ug/l of blood36. All other

ones were within the range of safe exposures. Lead contamination has therefore

not been as serious as calcium in the environment. Donors of samples 5 and 9

may have been exposed to lead through ingestion, inhalation or even absorption

3 7

through the skin. I t is possible that motor mechanics absorb lead through the

skin.

Lead toxicity manifest mainly in three organs namely; haematological,

central nervous and renal systems. The symptoms include mild anaemia,

production of abnormal red cells, and basophilic cells with nuclear abnormalities.

Others include central and peripheral nervous systems dysfunction leading to

cerebellum, spinal cord, motor and sensory nervous problems26. As Pb toxicity is

cumulative, it also affects kidney function. Other symptoms are liver dirrhosis,

bone 'deformity and brain damage which may lead to general intellectual and

psychological impairment in children27.

Lead toxicity symptoms sometimes do not manifest immediately as it

depends on the concentration of diffusible lead in soft tissues. However, the

body can convert the diffusible form to non-diffusible state in ~ i d n e ~ ~ ~ . Lead

poisoning can also be reduced by intake of diets rich in zinc which enhances the

formation of metallothionein in soft tissues. Dietary intake of Ca, Fe, Cu and P

reduces Pb metabolism in the body. Chelating agents like CaNa-EDTA,

dimercaprol and 2-3 dimercaptosuccinic acid (succimer DMSA) can be used.

These provide sulfhydryl groups of metallothionein for which lead has much

affinity'. The complex can be eliminated through urine, faeces, sweat and milk".

Chromium is a micro nutrient in man. I t is needed in insulin activity and

membrane transport of cell metabolites. The results of the analysis revealed that

the concentrations.of chromium in the blood samples were low and could not be

detected in most of the samples. This may probably be as a result of low

absorption of the ingested metal into the body irrespective of its dose. The body

can also convert the hexavalent chromium to trivalent chromium in the stomach.

Thus there is wide margin of safety with regards to chromium toxicity.

4.3 CONCLUSION

The results of the analysis of human (adult) whole blood samples indicate

the extent of environmental pollution. From the result, about 72.7O/0 of the

samples have cadmium concentration more than 5ug/l. 18.2O/0 of the samples

have concentrations of lead to be more than the limit of safe exposure which is

300ug/l. All the samples had low concentrations of chromium.

All these indicate that our environment is getting more contaminated with

cadmium as a result of different human activities like transportation, and

emission of urban and industrial wastes into the total environment (air, water,

and land).

4.4 RECOMMENDATIONS

From the results of this research work, the followings are recommended:

1. People should be made to understand the importance of safe environment.

This will encourage them to maintain good and clean environment.

2. The public should be given the awareness on what environmental pollution is

all about, its dangers and effects on living organisms including man. This will

educate everyone to protect himself well against pollutants and encourage

. proper disposal of wastes.

3. New technologies should be adopted for recycling of wastes (where

applicable) to reduce the volume of wastes that will be channeled into the

environment.

4. The use of toxic materials should be substituted with the ones less toxic

(where there are alternatives).

5. The effluents from industries should be properly treated before releasing into

the environment.

6. Government should make it a point of duty to provide funds and facilities for

proper disposal of wastes especially in urban areas.

7. Bio-degradable materials should be used as containers and wrappers more

than the non-bio-degradable ones.

' 8. Scientists should be encouraged to go into environmental analysis in order to

ascertain the levels of pollution and the possible solutions that can be

proffered.

. 9. Individuals should be encouraged to know the level of heavy metal- in their

systems. This will help in directing them to the required diets or treatments

that could be given to reduce the toxicities of the metals (where applicable).

This will save much and even increase life spans of individuals.

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