ASSESSMENT OF HEAVY METALS IN TWO COMMONFISH SPECIES (Solea solea & Pseudolithus spp)

FROM LAGOS AND COCOA LAGOONS IN LAGOS ANDDELTA STATES.

ODUMUYIWA OYEPERO 'FUNMILAYO

MATRIC NO.04/0341

A PROJECT WORK SUBMITTED TO THE DEPARTMENT OFENVIRONMENTAL MANAGEMENT AND TOXICOLOGY IN THECOLLEGE OF ENVIRONMENTAL RESOURCE MANAGEMENT

IN PARTIAL FULFILMENT FOR THE AWARD OF BACHELOR OFENVIRONMENTAL MANAGEMENT & TOXICOLOGY

ABSTRACf

This study investigated the levels Pb, Cd, Cu, Cr and Zn in two common edible fish species

(Solea solea and Psedolithus spp) from Lagos lagoon & cocoa lagoon of Lagos and Delta States

respectively. The levels of the heavy metals were determined by air-acetylene flame Atomic

Absorption Spectrophotometer after wet digestion of powdered samples with 1:1 HNOJ!H202 .

The mean results obtained (Ilg/g, dry weight) for Solea solea in Lagos Lagoon are as follows; Pb

(0.330), Cd (0.097), Cu (0.869), Cr (1.184), and Zn (7.612). While the mean results obtained

(Ilglg, dry weight) for Pseudolithus spp in Lagos lagoon are; Pb (0.163), Cd (0.115), Cu (0.990),

Cr (1.008) and Zn (6.756). The mean results obtained (Jlglg, dry weight) for Solea solea in

Cocoa Lagoon are as follows; Pb (0.149), Cd (0.063), Cu (0.434), Cr (0.826), and Zn (7.890).

While the mean results obtained (Ilglg, dry weight) for Pseudolithus spp in Lagos lagoon are; Pb

(0.045), Cd (0.029), Cu (0.694), Cr (1.038) and Zn (6.168).

Results for heavy metals in fish samples were compared with international standards' tolerable

values of of heavy metals in fish (Ilglg), as well as literature data reported for fishes and between

the two states where the study was carried out. The obtained results showed that the mean values

of Cd and Cr in the fish samples were higher than the tolerable levels.

Generally, Solea solea showed higher levels of metal concentrations than Psedolithus spp. Metal

contamination was higher in samples from Lagos lagoon in Lagos state compared to cocoa

lagoon in Delta state, probably due to inclusion of more effluents from industrial, commercial

and municipal discharges from Lagos state and environs. Chronic Cr and Cd health effecm may

occur in people that consume fishes from Lagos lagoon and cocoa lagoons.

DEDICATION

I dedicate this project to God Almighty who before I was formed in my mother's womb knew

me and who has brought me this far. Jesus Christ who was here yesterday, is here today and will

still be here tomorrow after I am no more. My God who has always been faithful to me even

when I am unfaithful.

ACKNOWLEDGEMENT

Many thanks to my parents Balogun K.O. Odumuyiwa and Deaconess T.A. Odumuyiwa for all

your love, care, support (spiritual, moral, financial, etc). I bless the Lord that I came to this world

through you and if were to choose, I'd be honoured to come again through you. Thank you for

not making lack anything. Love you dearly

Mejiola, you are everything to me. Thank you for all the vigils and all the times you spent

praying for us and for being so strong. Words cannot express it ara isokun , edunjobi, oba omo.

May you reap the fruits of your labour. Love you mummy.

To my supervisor Prof T.A. Arowolo, thank you sir for being a pillar of support and strength to

me through out the period I was privileged to learn at your feet. Thank you for being a father to

To my siblings, the Adepojus, the Dosumus, Ayokunle Martins & family, Mr. Olajide Martins,

Adebayo & Adegboyega Odumuyiwa. Thanks for everything and for the support. I appreciate

you all for your contributions towards this project work and to my life in general. Love you all.

To all my lecturers in EMT department for imparting your knowledge in me especially my level

adviser; Mr. B.S. Bada Prof Bamgbose, Reader. Adeofun, Dr. Gbadebo, Dr. (Mrs). Adekunle,

Mrs. Ademola-Aremu, Dr. Oguntoke,

To all the staffs in the EMT lab; Mrs. Sorinola, aunty funmi, Mr. Olopade, Mr. Babs, Mr. Fidelix

and Mummy Ope. Thanks for your help through out my Working period in the lab, I really

appreciate it.

To my friends Adepeju Kasali, Olaitan Ipadeola, Abibat Akande, Omotayo OgunmokWl,

Olumide Reis, Oluwaleke Adenaiye, Damola Masha, Tomilayo Adeyeye, AdetoWl

~ekodWlmi, Mosope Owolabi, Debo Sobowale (Dj Debolic), AkinkWlmi .Oyebade (mome),

Opeoluwa FatokWl, Pst. Tolu Taiwo, all EMf graduates of class '10 and a host of others too

numerous to mentions. Thank you all for being a part of the long journey and see you at the top.

To my housemates; Damilola Fanimo (damoch), Tomi Elebute, Funmilola Akinbode, Quadri

Aliyu & Seyi Abodunde. It was such a short time we spent together and I enjoyed it all. Thank

you for putting up with all my wahalas.

CONTENT

Title page

Abstract

Dedication

Acknowledgement

Certification

Table of contents

List of Tables

List of figures

CHAPTER ONE

1.0 Introduction

1.1 Justification

1.2 Objectives

CHAPTER TWO

2.0 Literature review

2.1.4 Chromium

2.1.5 Zinc

CHAPTER THREE

3.0 Materials and Method 25

3.1 Sampling 25

3.2 Sample Preparation 25

3.3 Sample Digestion 25

3.4 Statistical Analysis 26

3.5 Sample coding 26

CHAPTER FOUR

4.0 Results and Discussion 27

CHAPTER FIVE

5.0 Conclusion and Recommendations 35

References 36

TABLE PAGE1. Concentrations of metals in Ilg/g offish samples from Lagos lagoon 27

2. Concentrations of metals in (Ilg/g) offish samples from cocoa lagoon 27

3. Mean, S.D and Range values ofPb (Ilg/g) in the fish spp. in both locations 28

4. Mean, S.D and Range values of Cd (Ilg/g) in the fish species in both locations 29

5 Mean, S.D and Range values ofCu (Ilg/g) in the fish species in both locations 30

6 Mean, S.D and Range values ofCr (Ilg/g) in the fish species in both locations 30

7 Mean, S.D and Range values ofZn (Ilg/g) in the fish species in both locations 31

8 Mean concentrations (~g/g) of Pb, Cd, Cu, Cr and Zn in the samples in comparison

with international standards 32

Lagos & Delta states are being used in this study because they are both coastal areas with lots of

shipping and freighting activities in their waters.

Lagos state which is surrounded by water and through which the Atlantic Ocean passes is

the industrial and commercial centre of Nigeria which implies that it has the highest number of

industries and arguably people in a state in the Nigeria and in Africa.

As a commercial hub and the industrial nerve centre of Nigeria with an estimated population

of more than 20 million people, environmental concerns are normally focused on Lagos State. Over

60% of Nigeria's industries are cited in the state, each discharging its characteristic range of

eftluents containing heavy metals into the terrestrial and aquatic ecosystems within the state.

The Lagos lagoon is the largest of the four Lagoon systems of the Gulf of Guinea Coast. It

is a shallow expanse of water with restricted circulation in a micro tidal environment. Typically, the

lagoon system in Lagos State is made up ofBadagry, Ologe, Lagos, Lekki and Epe lagoons which

act as sink or reservoir receiving eftluents of over 10,000 m3 daily from drainages through different

parts of the metropolis and hinterland, (Adefemi et al., 2008, Oyewo & Don-Pedro, 2003).

Expectedly therefore, studies have been conducted on fish which is a highly valued food

that contain balance level of amino acid, vitamin B12 cholesterol, high polysaturated fatty and it

accounts for 40% of the animal protein in the diet of Nigerians (Atta et al.,1997). Coastal fisheries

provide a yearly average of92.2% of the total fish production and are dependent on riverine, lagoon

and inshore water. Epe and Badagry lagoons are veritable sources of fishery in Nigeria but

surprisingly, it has received little attention in heavy metal studies relative to the Lagos Lagoon

1

known widely as a sink for these metals from various industries spread across Lagos State, (Atta et

al.,1997, Majolagbe & Bamgbose, 2007).

Recent studies have shown for instance that human activities have created ecological

pressure on the natural habitat of fish and other marine organism over time. There is an upsurge of

interest in water pollution as a result of this deleterious effect. Furthermore, factors such as high

population growth accompanied by intensive urbanization, increase in industrial activities and

higher exploitation of natural resources including cultivable land have caused pollution increase.

There has been a steady increase in discharges that reaches the aquatic environment from industries,

(Atta et al.,1997.

Large amount of organic material are released into the water body although some industrial

process such as pump mill and sugar processing plant also produce much finely divided organic

material as waste product, which is broken down easily by bacteria activities resulting in the

reduction of oxygen level or even anaerobic condition in the vicinity of an eflluent (Majolagbe &

Bamgbose, 2007, Jibiri & Adewuyi, 2008). In addition to direct depletion of oxygen, the

decomposition oflarge quantities of organic material in the water produces inorganic nutrients such

as ammonia, nitrate and phosphorus. These enrich the water considerably and give rise to dense

algae growth or bloom which can cause the wide daily fluctuations in oxygen described for fish

pound and in extreme condition, fish - kill can result. This increased productivity caused by

excessive organics load can cause a decline in water quality and this symptom of over production is

known as eutrophication.

Sediments have been reported to form the major repositoIY of heavy metal in aquatic system

while both allochthonous and autochthonous influences could make a concentration of heavy

metals in the water high enough to be of ecological significance, (Atta et al.,1997, Ikem et al.,

2003).

Bioaccumulation and magnification is capable of leading to toxic level of these metals in

fish, even when the exposure is low. The presence of metal pollutant in fresh water is known to

disturb the delicate balance of the aquatic ecosystem. Fishes are notorious for their ability to

concentrate heavy metals in their muscles and since they play important role in human nutrition,

they need to be carefully screened to ensure that unnecessary high level of some toxic trace metals

are not being transfer to man through fish consumption (Adeniyi & Yusuf, 2007).

Delta state is located in the Niger-Delta region of Nigeria and the region is very rich in

petroleum deposit. Oil exploration and exploitation has uplifted Nigerian economy leading to rapid

development but the impacts of oil exploration and exploitation on the environment are receiving

less attention (Idodo-Umeh, 2002). One of the major anthropogenic sources of heavy metal

enrichment in aquatic habitats of oil producing areas of Niger Delta of Nigeria is the frequent spills

of crude oil in the waters of the region, dumping of petroleum effluents and gas flaring (Idodo-

Umeh, 2002). Nigerian crude oil is known to contain heavy metals such as AI, Zn, As, Ba, Fe, Pb,

Co, Cu, Cr, Mn, Ga, Sb, Ni and V (Unpublished data). Toxicity of ingested heavy metals has been

an important health issue for decades (LeCoultre, 2001).

Water pollutants are categorized as emitted from point or non. point sources. Point sources

are distinct and confined, and include accidental spills from industrial sites that empty into streams

or rivers. Non-point sources, such as run-off, are diffused and intermittent and are influenced by

factors such as land use, climate, hydrology, topography, native vegetation and geology, Common

urban non point sources include Urban run-off from streets or fields, such run off contains all sorts

of pollutants from heavy metals to chemical and sediments. Rural sources of non point pollutants

are generally associated with agriculture, mining or forestry. Non point sources are difficult to

monitor and control (Botkin & Keller 1998). The hazard presented by a particular water pollutant

depends on several factors including the concentration or toxicity of the pollutants in the

environment and the degree of exposure to people or other organisms. (Pye & Patrick 1983).

According to a world bank's report published in 1993 over 80% of the industries worldwide

discharge solid, liquid and gaseous effluents directly into the environment without Prior treatment.

Recent works suggest that toxic materials threaten the ocean bottom as well as the entire marine

ecosystem. The base of the marine food chain consists of the planktonic life abundant in the upper

3mm of the ocean water. The young of certain fish and shell fish also reside in the upper few

millimeters of the ocean also tend to concentrate pollutants such as toxic chemicals and heavy

metals. One study reported that the concentration of heavy metals including zinc, lead, and copper

in the upper 3mm (or micro layer) are froml0 to 1000 times higher than in the deepest waters, i.e.

surface film enrichment.(chemical oceanography, 2nd edition) There is fear that disproportionate

pollution of the micro layer will have especially serious effects on marine organisms (leussen-

1989). Marine pollution can also have major impacts on people and society. Contaminated marine

organisms may transmit toxic elements or diseases to people who eat them (Chemical

Oceanography, 1970).

The pollution of the aquatic environment with heavy metals has become a worldwide

problem during recent years, because they are indestructible and most of them have toxic effects on

organisms (MacFarlane and Burchett, 2000). Among environmental pollutants, metals are of

particular concern, due to their potential toxic effect and ability to bioaccumulate in aquatic

ecosystems (Censi et a/. , 2006).

Heavy metal concentrations in aquatic ecosystems are usually monitored by measuring their

concentrations in water, sediments and biota (Camusso et aI., 1995), which generally exist in low

levels in water and attain considerable concentration in sediments and biota (Namminga and

Wilhm, 1976). Heavy metals including both essential and non-essential elements have a particular

significance in eco-toxicology, since they are highly persistent and all have the potential to be toxic

to living organisms (Storelli et al, 2005).

In the recent years, the concern over heavy metal pollution in the marine environment has

become a rising concern due to the human activities that contribute significantly to the release of

these heavy metals in the environment. According to a study (Skejelkvale et al., 2001) that heavy

metals in the environment are brought about primarily by anthropogenic sources though heavy

metals are a part of the natural environment and provide numerous benefits to society.

Most of the heavy metals that get deposited in most water bodies are due to those coming

from coal and oil combustion, internal combustion engines, local point sources, and in direct

deposition from air pollution, and bedrock geology and soils (Skejelkvale et al., 2001). This grave

concern posed by heavy metals in the environment creates an immense threat to the existence of

organisms thriving in the area, to the ecological integrity of the habitat as these heavy metals may

enter the food chains, persist in the environment, bio-accumulate and bio-magnify and increase the

exposure to public health risks.

These two (2) states in which the study is being carried out are riverine areas and they are

two very important states in different areas with respect to the aquatic environment.

The concern about the ecological consequences of discharges of effluents from the Nigerian

Oil Industry and domestic sewage and particularly the environmental effects of heavy metal

substances released from Oil manufacturing, Textile and mining industries has been widespread in

recent years. The importance for public health i.e. the quality offish and fishery products) of heavy

metals contamination in fish is critical and hence need to be monitored.

The local and indigenous dish of the people of these two states is seafood especially fishes

caught in their rivers. It is also their heritage and a cheap source of protein which is consumed by a

majority and so, there is a need to find out and know the risks involved in consuming the fishes.

The objective of this project therefore, is to determine the concentration of Cd, Cr, Pb and

Zn as heavy trace metals in the two (2) common fish species: croaker -Pseudotolithus spp,

commonly found in the upper part of the river and sole - Solea solea commonly found at the

bottom of the river right on top of the sediments i.e. a benthic fish; both from Lagos and cocoa

lagoons in Lagos and Delta States ..

Fish contains polyunsaturated fats, which are essential for human nutrition and their

consumption should increase. Contamination of freshwater fish with heavy metals (HMs) is a

recognized environmental problem. The World Health Organization as well as the Food and

Agriculture Organization of the United Nations state that monitoring eight elements in fish - Hg,

Cd, Pb, As, Cu, Zn, Fe, Sn - is obligatory and monitoring of others is suggested.

Studies on heavy metals in rivers, lakes, fish and sediments (Ozrnen et al., 2004; Begum et

aI., 2005; Fernandes et a/., 2008; Oztiirk et al., 2008; Pote et aI., 2008 sand Praveena et a/., 2008)

have been a major environmental focus especially during the last decade. Sediments are important

sinks for various pollutants like pesticides and heavy metals and also playa significant role in the

remobilization of contaminants in aquatic systems under favorable conditions and in interactions

between water and sediment. Fish samples can be considered as one of the most significant

indicators in freshwater systems for the estimation of metal pollution level (Rashed, 2001). The

commercial and edible species have been widely investigated in order to check for those hazardous

to human health (Begum et aI., 2005).

Heavy metals such as copper, iron, chromium and nickel are essential metals since their

play an important role in biological systems, whereas cadmium and lead are non-essential metals,

as they are toxic, even in trace amounts (Fernandes et aI., 2008). For the normal metabolism of the

fish, the essential metals must be taken up from water, food or sediment (Canh and Ath, 2003).

These essential metals can also produce toxic effects when the metal intake is excessively elevated

(Tiizen,2003).

Earlier reports showed that industrial and domestic effluent constitute largest sources of

heavy metal which contribute to the steadily increasing metallic contaminant in aquatic and

terrestrials environment in most part of the world (Jibiri and Adewuyi, 2008, Ayodele et al., 1991,

Oshodi and Ipinmoroti, 1991).

More studies in the distribution of heavy metals in water bodies reveal that the levels of

heavy metals in the bottom sediment are usually higher than in the water columns which shows that

sediments acts as sink for heavy metal (Attah et al., 1997, Adeniyi and Yusuf, 2007).

Usually, many toxic compounds affect organisms in nature at the same time, each of them

having a specific effect on physical and chemical processes that influence an organism's condition

and reactions. Therefore, in order to maintain the quality of food it is important to regularly monitor

and evaluate the pollution levels in fish as well as in water reservoirs.

Metals are non-biodegradable and are considered as major environmental pollutants causing

cytotoxic, mutagenic and carcinogenic effects in animals (More et a/., 2003). Aquatic organisms

have the ability to accumulate heavy metals from various sources including sediments, soil erosion

and runoff, air depositions of dust and aerosol, and discharges of waste water (Labonne et al., 2001;

Goodwin et a/., 2003). Therefore, accumulation of heavy metals in aquatic organisms can pose a

long lasting effect on biogeochemical cycling in the ecosphere. Heavy metals can also adversely

affect the growth rate in major carps (Hayat et aI., 2007)

Fish are often at the top of aquatic food chain and may concentrate large amounts of some

metals from the water (Mansour and Sidky, 2002). Metal bioaccumulation is largely attributed to

differences in uptake and depuration period for various metals in different fish species (Tawari-

Fufeyin and Ekaye, 2007). Multiple factors including season, physical and chemical properties of

water (Kargin, 1996) can playa significant role in metal accumulation in different fish tissues. The

gills are directly in contact with water. Therefore, the concentration of metals in gills reflects their

concentration in water where the fish lives, whereas the concentrations in liver represent storage of

metals in the water (Romeo et al., 1999).

Natural and anthropogenic activities result in gaseous emissions and wastewater discharges

into air, water and land. When the substances in the emissions and effluent discharges in the

environment are in very minute amounts or in low concentrations, are toxic to plants and animals

and have short residence time in the environment, they are described as 'contaminants' (Odiete,

1999). Bio-concentration is the net accumulation of a substance from water into an aquatic

organism resulting from the simultaneous uptake and elimination of the substance. Fish and bivalve

molluscs are used in bioaccumulation tests because they are higher tropic level organisms and are

usually eaten by man. Tissues such as liver, kidney, muscle, viscera and whole organisms are

analyzed to determine the concentration of the metals (Dublin-Green, 1994).

Once these metals enter the environment their potential toxicity is determined by the form

of existence (Nwadozie, 1998). These metals could be ingested directly through drinking or

indirectly by consumption of plants cultivated along the bank of the water body and through the

consumption of aquatic animals such as fishes and crabs (Mathias & Kevem, 1995).

Fish is the most susceptible of the aquatic fauna to these metals, it is cheap, easy to get and

it is consumed in different forms such as boiling, frying in deep oil, smoking, sun drying amongst

others (Nriagu,1988). The physical and chemical environment in which the fish resides appears to

influence the rate ofbioaccumulation of trace elements in fish (Singh & Sahai, 1986).

Fish is generally appreciated as one of the healthiest and cheapest source of protein and it

has amino-acid compositions that are higher in cysteine than most other source of protein (Duffus,

1980). The effects of exposure to any hazardous substance depend on the dose, the length of time,

the mode of exposure, personal habits, traits, and whether other chemicals are present (perazo et al.,

1998). Zn, Fe, Cr, Pb, and Mn have been reported to have adverse effect on aquatic life when

present in higher than required amounts even though some of them are essential (Macrae et

al.,1993)

Manganese in exceSSIve amounts affects animals adversely causmg tremors and

hallucination, manganic pneumonia, and renal degradation. The poisonous effects of lead (Ph) is

one of the reasons why attempts are being made to eliminating lead (Pb) from gasoline. Excess

chromium has been implicated in diseases such as chromosome abnormalities and kidney damage

(Macrae et al.,1993). Chromium is a potent allergen and it is a common skin sensitizer in allergic

eczema. In USA, the suggested safe and adequate intake of Cr for adult and children over Two (2)

yrs is 50-200pg/day (Trieff, 1980).

Animal protein intake remains the surest way to furnish the body with a complete assay of

all the needed amino acids required for proper tissue formation, growth and repair. The common

animal protein sources in Nigeria include fish, beef and mutton. The habitat of these animals are

continually been polluted with heavy metals discharged as a result of industrial activities. These

metals find their way into the food chain of these animals and consequently build up in these

animal products. When these animal products are consumed, the heavy metals in them produce

pathologies relative to quantity and period of time consumed. This explains why the presence of

heavy metals in animal products has continued to receive a lot of attention from nutritionists and

environmental scientists. The main threats to human health from heavy metals are associated to

exposure to lead, cadmium, mercury and arsenic (Lars, 2003). Excessive intake of these toxic heavy

metals can lead to several diseases such as organ failure cancer and retarded mental development,

especially in children and foetus in pregnant women. It has been reported that acute large dose of

arsenic causes gastrointestinal damage with profuse watery diarrhea, bleeding and death (Dodd,

1984).

A heavy metal is a member of an ill-defined subset of elements that exhibit metallic

properties, which would mainly include the transition metals, some metalloids, lanthanides, and

actinides. Many different definitions have been proposed-some based on density, some on atomic

number or atomic weight, and some on chemical properties or toxicity (Morel &Lane). Heavy

metals occur naturally in the ecosystem with large variations in concentration. In modem times,

anthropogenic sources of heavy metals, i.e. pollution, have been introduced to the ecosystem.

Waste-derived fuels are especially prone to contain heavy metals so they should be a central

concem in a consideration of their use. Some of which are; Aluminium (AI), Antimony (Sb),

Arsenic (As), Barium (Ba), Cadmium (Cd), Cobalt (Co), Chromium (Cr), Copper (Cu), Iron (Fe),

Nickel (Ni), Lead (Pb), Manganese (Mn), Molybdenum (Mo), Rubidium (Rb), Scandium (Sc),

Selenium (Se), Strontium (Sr), Tin (Sn), Titanium (Ti), Tungsten (W), Vanadium (V), Zinc (Zn).

Heavy metals are natural constituents of the Earth's crust. They are stable and cannot be degraded

or destroyed, and therefore they tend to accumulate in soils and sediments. However, human

activities have drastically altered the biochemical and geochemical cycles and balance of some

heavy metals. The principal man-made sources of heavy metals are industrial point sources, e.g.

mines, foundries and smelters, and diffuse sources such as combustion by-products, traffic, etc.

Relatively volatile heavy metals and those that become attached to air-bome particles (particulates)

can be widely dispersed throughout the atmosphere, often being deposited thousands of miles from

the site of initial release. In general, the smaller and lighter a particle is, the longer it will stay in the

air. Larger particles (>1011min diameter) tend to settle to the ground by gravity in a matter of hours

whereas the smallest particles (less than 111min diameter) can stay in the atmosphere for weeks

and are mostly removed by precipitation.

In general heavy metals produce their toxicity by forming complexes or "ligands" with

organic compounds. These modified biological molecules lose their ability to function properly,

and result in malfunction or death of the affected cells. The most common groups involved in

ligand formation are oxygen, sulfur, and nitrogen. When metals bind to these groups they may

inactive important enzyme systems, or affect protein structure.

Heavy metals are dangerous because they tend to bioaccumulate. Bioaccumulation means

an increase in the concentration of a chemical in a biological organism over time, compared to the

chemical's concentration in the environment. Compounds accumulate in living things any time they

are taken up and stored faster than they are broken down (metabolized) or excreted.

Lead is a main-group element with symbol Pb (Latin: plumbum) and atomic number 82. It

is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a

bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed

to air. Lead has a shiny chrome-silver luster when it is melted into a liquid.

Lead is used in building construction, lead-acid batteries, bullets and shots, weights, as part

of solders, pewters, fusible alloys and as a radiation shield

Lead is a pOisonous metal that can damage nervous connections (especially in young

children) and cause blood and brain disorders. Lead poisoning typically results from ingestion of

food or water contaminated with lead; but may also occur after accidental ingestion of

contaminated soil, dust, or lead based paint (ATSDR, 2005).

Acute lead poisoning usually manifest itself in gastro intestinal effects, anorexia, dyspepsia,

constipation, attack of colic with intense paroxysmal abdominal pain, bone pain, brain damage,

confusion, convulsions, dizziness drowsiness, fatigue, headaches, hypertension, memory

difficulties, inability to concentrate, indigestion and irritability (Blood, 1969; Anonymous 2002a,b).

Excessive intake of lead can also lead to damage to the brain, liver, kidney and reproductive

systems (Hauser and Hauser, 2009).

Long-term exposure to lead or its salts (especially soluble salts or the strong oxidant Pb02)

can cause nephropathy, and colic-like abdominal pains. The effects of lead are the same whether it

enters the body through breathing or swallowing. Lead can affect almost every organ and system in

the body. The main target for lead toxicity is the nervous system, both in adults and children. Long-

term exposure of adults can result in decreased performance in some tests that measure functions of

the nervous system. It may also cause weakness in fingers, wrists, or ankles. Lead exposure also

causes small increases in blood pressure, particularly in middle-aged and older people and can

cause anemia. Exposure to high lead levels can severely damage the brain and kidneys in adults or

children and ultim~tely cause death. In pregnant women, high levels of exposure to lead may cause

miscarriage. Chronic, high-level exposure have shown to reduce fertility in males.(Golub & Maris,

2005). The antidote/treatment for lead poisoning consists of dimercaprol and succimer.

The concern about lead's role in cognitive deficits in children has brought about widespread

reduction in its use (lead exposure has been linked to learning disabilities). Most cases of adult

elevated blood lead levels an~ workplace-related. High blood levels are associated with delayed

puberty in girls. Lead has been shown many times to permanently reduce the cognitive capacity of

children at extremely low levels of exposure. There appears to be no detectable lower limit below

which lead has no effect on cognition.

According to Agency for Toxic Substance and Disease Registry, a small amount of lead

(1%) will store itself in bones and the rest will be excreted through urine and feces within a few

weeks of exposure. Children have a harder time excreting lead. Only about 32% of lead will be

excreted by a child (ATSDR, 2005),

Cadmium is produced as an inevitable by-product of zinc (or occasionally lead) refining,

since these metals occur naturally within the raw ore. However, once collected the cadmium is

relatively easy to recycle.

Pratter, (1981) observed that cadmium is not a biological essential or beneficial element, but

it IS associated with various deleterious effects. Cadmium has been found to be teratogenic,

carcinogenic and possibly mutagenic (Young and Bevins, 1981). Hauser and Hauser, (2009)

reported that high doses of cadmium can lead to kidney failure, damage to testicles and liver.

The most significant use of cadmium is in nickel/cadmium batteries, as rechargeable or

secondary power sources exhibiting high output, long life, low maintenance and high tolerance to

physical and electrical stress. Cadmium coatings provide good corrosion resistance, particularly in

high stress environments such as marine and aerospace applications where high safety or reliability

is required; the coating is preferentially corroded if damaged. Other uses of cadmium are as

pigments, stabilizers for PVC, in alloys and electronic compounds. Cadmium is also present as an

impurity in several products, including phosphate fertilizers, detergents and refined petroleum

products.

In the general, non-smoking population the major exposure pathway is through food, via the

addition of cadmium to agricultural soil from various sources (atmospheric deposition and fertilizer

application) and uptake by food and fodder crops. Additional exposure to humans arises through

cadmium in ambient air and drinking water

In the past, acute cadmium intoxication occurred after oral ingestion of acidic foods or

beverages stored in cadmium-plated containers, with symptoms of abdominal cramps, diarrhoea,

salivation, severe nausea, and vomiting. In humans, single lethal oral doses of soluble cadmium

salts have ranged from 30-40 mg. (ATSDR, 1999; Drebler, 2002)

In the general population, ingestion of cadmium-contaminated food is more likely to occur

than inhalation of cadmium particles. Oral ingestion is the major route of exposure for the non-smoking

general population. Adverse effects of excessive chronic cadmium exposure may include; chronic

obstructive pulmonary disease (inhalation only), chronic renal failure, kidney stones, liver damage

(rare), lung cancer, osteomalacia, possibly hypertension, prostatic cancer, and proteinuria. Chronic

cadmium exposure has been reported to cause mild anemia, Skeletal Lessions, Itai-itai disease,

anosmia, and yellowing of teeth. Cadmium is. a cumulative toxin. Its levels in the body increase

over time because of its slow elimination. It accumulates chiefly in the liver and kidneys (ATSDR

However, it also accumulates in muscle and bone. The principal organs affected by

cadmium's toxicity, both acutely and chronically, are the: kidneys, bone, and lungs. Cadmium

expresses genotoxic activities in vitro in cells and in vivo in animals; and there is limited

epidemiological evidence for in vivo human genotoxicity.

Cadmium has been found to cause chromosomal damage in animal experiments with

subcutaneous administration (ATSDR 1999). Cadmium causes mutations, DNA strand breaks,

chromosomal damage, cell transformation and impaired DNA repair in cultured mammalian cells,

(NTP 2004). Cadmium is known to modulate gene expression and signal transduction (Waisberg et

al. 2003). Cadmium is also a known testicular, prostate and lung carcinogen, (Sahmoun et aI., 2005;

ATSDR,1999).

Because excretion is slow, cadmium accumulation in the body can be significant. Cadmium

concentration in blood reflects recent exposure; urinary cadmium concentration more closely

reflects total body burden. However, when renal damage from cadmium exposure occurs, the

excretion rate increases sharply, and urinary cadmium levels no longer reflect body burden.

The biologic half-life of cadmium in the kidney is estimated to be between 6 to 38 years; the

half life of cadmium in the liver is between 4 and 19 years (ATSDR 1999). These long half-lives

reflect the fact that humans do not have effective pathways for cadmium elimination. Cadmium has

no known biologic function in humans. Bioaccumulation appears to be a by-product of increasing

industrialization. Any excessive accumulation in the body should be regarded as potentially toxic.

exists as cadmium sulphide, is refined during zinc production, and occurs in association with zinc.

The major sources of release are mInIng operations, agriculture, sludge from publicly-

owned treatment works (POTWs) and municipal and industrial solid waste. Mining and milling

contribute the most waste. Copper is released to water as a result of natural weathering of soil and

discharges from industries and sewage treatment plants. Copper compounds may also be

intentionally applied to water to kill algae.

Industrial releases are only a fraction of the total environmental releases of copper and

copper compounds. Other sources of copper release into the environment originate from domestic

waste water, combustion processes, wood production, phosphate fertilizer production, and natural

sources (e.g., windblown dust, volcanoes, decaying vegetation, forest fires, sea spray, etc.),

(Georgopoulos et al. 200 I).

Much of the copper tha~ enters environmental waters will be associated with particulate

matter. Copper is a natural constituent of soil and will be transported into streams and waterways in

run-off either due to natural weathering or anthropogenic soil disturbances. Sixty-eight percent of

17

releases of copper to water is estimated to derive from these processes. Copper sulphate use

represents 13% of releases to water and urban runoff contributes 2% (Perwak et aI. 1980). In the

absence of specific industrial sources, runoff is the major factor contributing to elevated copper

levels in river water (Nolte 1988). In the EPA-sponsored National Urban Runoff Program, in which

86 samples of runoff from 19 cities througho'ut the United States were analyzed, copper was found

in 96% of samples, at concentrations of 1-100 IlglL (ppb) with a geometric mean of 18.71lglL (Cole

et al. 1984). This mean concentration of copper in runoff water is higher than the geometric mean

concentration of 4.2 ppb for copper in surface water based on measurements in EPA's STORET

database (Eckel and Jacob 1988).

Domestic waste water is the major anthropogenic source of copper in waterways (Isaac et al.

1997; Nriagu and Pacyna 1988). Studies in Cincinnati and St. Louis showed discharges of copper

into sewer systems from resic,lential areas to be significant, with an average loading of 42

mg/person/day (Perwak et al. 1980).

A source of copper relea<;ed into waterways is from urban storm water runoff. Copper in storm

water runoff originates from the sidings and roofs of buildings, various emissions from

automobiles, and wet and dry depositional processes (Davis et aI. 2001)

Runoff from abandoned mines is estimated to contribute 314 metric tons annually to surface

water (Perwak et al. 1980). These discharges are primarily insoluble silicates and sulphides and

readily settle out into stream, river, or lake beds. Releases from manufactured products containing

copper may be substantial, but are difficult to predict. Corrosion of copper in plumbing or

construction may result in direct discharges or runoff into waterways. Copper and brass production

releases relatively little copper to water.

Effluents from power plants that use copper alloys in the heat exchangers of their cooling

systems discharge copper into receiving waters (Harrison and Bishop 1984). A potential source of

copper release into waterways is leachate from municipal landfills. Copper concentrations in

leachate obtained from waste sites have been found to vary widely. Copper can enter surface waters

as a result of agricultural runoff.

Bioconcentration and Biomagnification in Copper

The bio-concentration factor (BCF) of.copper in fish obtained in field studies is 10-667,

indicating a low potential for bio-eoncentration (Perwak et al. 1980). The BCF is higher in

mollusks, such as oysters, and squid where it may reach 30,000 and 2.1X 107 respectively, (Perwak

et aI. 1980) and may present a major dietary source of copper that could be of concern for those

individuals who regularly consume oysters, clams, or squid. Due to the fact that molluscs are filter

feeders and copper concentrations are higher in particulates than in water, this is to be expected. On

the other hand, there are limited data suggesting that there is little biomagnification of copper in the

aquatic food chain (Perwak et al. 1980). For example, a study was conducted with white suckers

and bullheads, both bottom-feeding fish, in two acidic Adirondack, New York, lakes (Heit and

Klusek, 1985). These lakes were known to have received elevated loadings of copper; but the

suckers and bullhead had average copper levels of only 0.85 and 1.2 ppm (dry weight) in their

muscle tissue. The biomagnification ratio (the concentration of copper in fish compared to that in

their potential food sources on a wet weight/wet weight basis) was <I, indicating no bio-

magnification in the food chain. Similarly, the copper content of muscle tissue of fish from copper-

contaminated lakes near Sudbury, Ontario, did not differ significantly from that of the same fish

species in lakes far from this source (Bradley and Morris] 986).

Health effects

Cardiovascular Effects, gastro-intestinal effect, hematological Effects, Hepatic Effects -

Wilson's disease, Indian childhood cirrhosis, and idiopathic copper toxicosis-liver effects are

rarely reported in humans, although this has not been extensively investigated.

2.1.4 CHROMIUM

Chromium is a chemical element which has the symbol Cr and atomic number 24, first

element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high

melting point. It is also odorless, tasteless, and malleable. The name of the element is derived from

the Greek word "chroma" (XlJc:OJ.la), meaning color, because many of its compounds are intensely

colored. It was discovered by Louis Nicolas Vauquelin in the mineral crocoite (lead chromate) in

1797. Crocoite was used as a pigment, and after the discovery that the mineral chromite also

contains chromium this latter mineral was used to produce pigments as well.

Although trivalent chromium (Cr(ill)) is required in trace amounts for sugar and lipid

metabolism, few cases have been reported where its complete removal from the diet has caused

chromium deficiency. It is toxic in larger amounts. Hexavalent chromium (Cr(VI)) is toxic and

carcinogenic, so that abandoned chromium production sites need environmental cleanup.

Chromium is the 21st most abundant element in Earth's crust with an average concentration

of 100 ppm (Ems ley, 2001). Chromium compounds are found in the environment, due to erosion of

chromium-eontaining rocks and can be distributed by volcanic eruptions.

Chromium has been suggested to be connected to sugar metabolism, although no biological

role for chromium has ever been demonstrated biochemically. The dietary supplements for

chromium include chromium(llI) picolinate, chromium(llI) polynicotinate, and related materials.

The benefit of those supplements is still under investigation and is questioned by some

studies.(Vincent, 2003; Heimbach & Anderson, 2005)

Chromium has found uses in; Metallurgy, Decorative chrome plating on a motorcycle., Dye and

pigment. The toxicity of chromium(VI) salts is used in the preservation of wood, Tanning,

Refractory material.

The acute toxicity of chromium(VI) is due to its strong oxidational properties. After it reaches the

blood stream, it damages the kidneys, the liver and blood cells through oxidation reactions.

Haemolysis, renal and liver failure are the results of these damages. Aggressive dialysis can

improve the situation (Salem, 1992).

The carcinogenity of chromate dust is known for a long time, and in 1890 the first

publication described the elevated cancer risk of workers in a chromate dye company (Newman,

1890 and Langard, 1990). Three mechanisms have been proposed to describe the genotoxicity of

chromium(VI).

Chromium salts (chromates) are also the cause of allergic reactions 1D some people.

Chromates are often used to manufacture, amongst other things, leather products, paints, cement,

mortar and anti-eorrosives. Contact with products containing chromates can lead to allergic contact

sdermatitis and irritant dermatitis, resulting in ulceration of the skin, sometimes referred to as

"chrome ulcers". This condition is often found in workers that have been exposed to strong

chromate solutions in electroplating, tanning and chrome-producing manufacturers (Basketter et al.,

2000).s

Low-level exposure can irritate the skin and cause ulceration. Long-term exposure can cause

kidney and liver damage, and damage too circulatory and nerve tissue. Chromium often

accumulates in aquatic life, adding to the danger of eating fish that may have been exposed to high

levels of chromium.

As chromium compounds were used in dyes and paints and the tanning of leather, these

compounds are often found in soil and groundwater at abandoned industrial sites, now needing

environmental cleanup and remediation per the treatment of brownfield land. Primer paint

containing hexavalent chromium is still widely used for aerospace and automobile refinishing

applications. Chromium is used in metal alloys and pigments for paints, cement, paper, rubber, and

other materials.

While zinc is one of the less hazardous elements, its toxicity may be enhanced by the

presence of As, Cd, and Pb as impurities. High intake of zinc, ascoIbic acid, and iron are common

in people who take large doses of vitamin and mineral supplements. Iron, depending on the form of

existence may, react with sulphide in the presence of water to produce sulphuric acid or react

directly with water to produce ferric hydroxide which makes the water body deficient in oxygen as

a result of its acidic characteristics thereby creating anaerobic condition resulting to death of fish.

Zinc is an essential nutrient for humans and animals that is necessary for the function of a

large number of metalloenzymes, including alcohol dehydrogenase, alkaline phosphatase, carbonic

anhydrase, leucine aminopeptidase, and superoxide dismutase. Zinc deficiency has been associated

with dermatitis, anorexia, growth retardation, poor wound healing, hypogonadism with impaired

reproductive capacity,

Health effects

Impaired Immune function, and depressed mental function; an increased incidence of

congenital malformations in infants has also been associated with zinc deficiency in the mothers.

Zinc deficiency may also have an impact on the carcinogenesis of other chemicals, although the

direction of the influence seems to vary with the carcinogenic agent. Water is polluted with zinc,

due to the presence of large quantities of zinc in the wastewater of industrial plants. This

wastewater is not purified satisfactory. One of the consequences is that rivers are depositing zinc-

polluted sludge on their banks. Zinc may also increase the acidity of waters. Some fish can

accumulate zinc in their bodies, when they live in zinc-contaminated waterways. When zinc enters

the bodies of these fish it is able to bio magnify up the food chain.

Cadmium is produced as an inevitable by-product of zinc (or occasionally lead) refining,

since these metals occur naturally within the raw ore. However, once collected the cadmium is

relatively easy to recycle.

Health effects of Zinc Deficiency

Zinc is a trace element that is essential for human health. When people absorb too little zinc

they can experience loss of appetite, decreased sense of taste and smell, slow wound healing and

skin sores. Zinc-shortages can even cause birth defects.

·All glass wares used were washed and rinsed, rinsed again with distilled water and then

10.00 g of dried samples in 60.00 mls of freshly prepared 1:1 HN03/ HzOz solution at 160°C on a

hot plate for about one hour until the contents came to about 5.00 mls. This was then filtered and the

filtrate was transferred to a standard flask and made up to 25.00 mls with distilled de-ionized water.

This was stored in plastic bottles and the concentrations ofPb, Cr, Cu, Cd and Zn were analyzed for

in the sample using air-acetylene flame AAS (AAnalyst 200, Perkin Elmer).

3.4 STATISTICS ANALYSIS

The data obtained were subjected to a one-way Analysis of Variance (ANOV A) according to the

procedure of Steel and Tome (1980). Significantly different means were separated using the

methods of Duncan. The values obtained were presented as Least Significance Differences (LSD)

of means at (p<0.05).

3.5 SAMPLE CODING

Sample were coded thus;

The numbers before the alphabets represent the time of sampling. 1, 2 & 3 represent June, Early

August & Late August respectively.

The first letter represents the state of sampling i.e. L for Lagos & D for Delta

The second letter represents the species of fish i.e. S for sole (solea solea) & C for croaker

(pseudolithus spp).

e.g.

2LS represents Early August Lagos sole while 3DC represents Late August Delta croaker, etc.

4.0

4.1 RESULT

TABLE 1

CHAPTER FOUR

RESULT AND DISCUSSION

I Mean (Ph) ~g1g I Mean(Cd) ~g1g I Mean (Cu) ~g1g I Mean (Cr) ~g1g I Mean (Zn) ~g1g ,

I LS , 0.603 0.124 0.730 1.873 7.908

2LS 0.387 0.059 0.470 0.918 6.677

3LS 0.000 0.109 1.407 0.760 8.252

LC 0.174 0.222 1.606 0.898 5.618

2LC 0.204 0.057 0.479 0.950 6.432

3LC 0.112 0.065 0.884 1.175 8.218

LSD 0.167 0.067 0.425 0.244 1.922

Mean (Ph) ~g1g Mean (Cd) ~g1g Mean (Cu) ~g1g Mean (Cr) ~g1g Mean (Zn) Jlglg

DS 0.256 0.116 0.678 1.034 6.969

2DS 0.190 0.040 0.366 0.721 8.327

3DS 0.000 0.033 0.258 0.723- 8.374

DC 0.041 0.063 1.008 0.943 5.784

2DC 0.094 0.024 0.621 1.002 6.401

3DC 0.000 0.000 0.453 1.168 6.318

LSD 0.167 0.067 0.425 0.244 1.922

The concentrations in the two (2) fish species from Lagos & Delta States are shown in table

1 & 2 respectively. The concentrations of metals in fish indicate the level of metal pollution of the

water from which it was caught. In the three (3) sampling periods, the metal found mostly abundant

in the fish was Zinc which ranged between 5.618-8.218Ilg/g Lagos state between 5.784-8.374Ilg/g

in Delta state as shown in Tables 1 & 2.

Copper is the second highest in the level of metals concentration and ranged from 0.470-

1.606Ilg/g and ranged from N.D-2.30 in Lagos and Delta states respectively. The high

concentrations of zinc and copper during the sampling periods could be associated with the fact that

this metals are naturally abundant in Nigerian soils and since the source of metal depositories are

the aquatic system (Adefemi et al., 2008, Kakulu & Osibanjo, 1988, Nwajei & Oruvwuje, 2001)

TABLE3

Mean, S.D and Range values ofPb (Ilg/g) in the fish species at the two locations

SAMPLE Mean S.D Range

LS 0.330 0.305514 ND-0.603

LC 0.163 0.046918 0.112 - 0.204

DS 0.149 0.132911 ND-0.256

DC 0.045 0.047127 ND-0.094

On average, the content of lead in muscle of fish from Delta was lower than that in fish

from Lagos. However, the mean values of sole fish was lower than that of croaker fish in Lagos

with values of 0.33 Ilg/g and 0.163 Ilg/g in respectively (Table 3) while in Delta, the lead content in

muscle of croaker fish was lower than that in sole fish with mean values of 0.149 J,J.g!g and 0.045

~g/g respectively.

The values reached were ND - 0.256 ~g/g & ND - 0.094 J.lg/g in sole and croaker fish

respectively from Delta, and ND - 0.603 ~g/g & 0.112 - 0.204 ~g/g in sole and croaker fish from

Lagos. The highest concentrations oflead were found to be 0.163~g/g in Lagos croaker and lowest

concentration was found to be ND in Delta croaker fish muscle.(fable 3).

SAMPLE

LS

LC

0.059~O.124

0.057 - 0.222

0.330-0.116

ND-0.063

0.097 ~g/g and 0.115 ~g/g, respectively while those of Delta were 0.063 ~g/g and 0.029 ~g/g

respectively. The concentrations in Lagos ranged from 0.059 to 0.I24~g/g and 0.057 - 0.222~g/g in

sole and croaker fish respectively while in Delta, the concentrations' ranges were 0.330 - 0.116

~g/g and ND to 0.063 J.lg/gin sole and croaker fishes respectively. The maximum concentration of

cadmium found in Lagos croaker fish with value of 0.115 ~g/g and the least cadmium concentration

was found in Delta croaker fish with a mean value of 0.029 ~g/g.,~,

TABLE 5

Mean, S.D and Range values ofCu (~g) in the fish species in Lagos & Delta states

SAMPLE

LS

LC

DS

DC

S.D

0.484

0.571

0.218

0.284

Range

0.470 - 1.407

0.479 -1.606

0.258 - 0,678

0.425 - 0.621

0.990

0.434

0.694

From Table 5 above, the mean concentrations of copper in muscle fishes from Delta were

much lower than levels in Lagos. Also, the mean concentrations of Cu in croaker fish were much

higher than those in sole fish in both states. Copper concentrations in Delta state was much lower

than in fishes from Lagos. Copper concentrations ranged from 0.470 to 1.4071lg!g and 0.479 to

1.6061lg/g in sole and croaker fishes in Lagos, and 0.258 to 0.678 & 0.425 to 0.6211lg!g in sole and

croaker fishes from Delta The lowest muscle copper concentrations were found to be 0.2581lg!g in

Delta sole while the highest was found to be 1.606Ilg/g in Lagos croaker fish (Table 5)

TABLE 6

Mean, S.D and Range values ofCr (Ilg!g) in the fish species in Lagos & cocoa lagoons

Mean S.D Range

LS 1.184 0.602 0.760-1.873

LC 1.008 0.147 0.896 - 1.175

DS 0.826 0.180 0.721-1.034

DC 1.038 0.117 0.943 - 1.168

Chromium results obtained for the two species and locations are summarized in Table 6.

Lagos had means of 1.184~g/g in sole and 1.008~g/g in croaker while in Delta, the means were

0.826~g/g in sole and 1.038~g/g. Chromium was detected in all the samples and the concentrations

were found to be 0.760-1.873~g/g & 0.896-1.175~g/g Lagos sole and croaker respectively while in

Delta, the values ranges were 0.721 -1.034~g/g & 0.943 -1.168~g/g in sole and croaker fishes

respectively. The highest concentration 1.184~g/g was detected in Lagos sole and the lowest was in

Delta sole fish 0.03 ~g/g (Table 6).

Mean, S.D and Range values ofZn (~g/g) in the fish species in Lagos & Delta lagoons

SAMPLE Mean S.D Range

LS 7.612 0.828 6.674 - 8.252

LC 6.756 1.330 5.618 - 8.218

DS 7.890 0.798 6.969 - 8.374

DC 6.168 0.335 5.784 - 6.401

The mean zinc concentrations in Lagos were 7.612~g/g & 6.756~g/g in sole and croaker

fishes respectively, while in Delta, the concentrations were 7.890~g/g & 6.168~g/g in sole and

croaker fishes respectively. In both states, the zinc concentrations of croaker fishes were much

lower than those of sole fishes. Zinc values in fish species varied from 6.674~g/g - 8.252~g/g &

5.618~g/g - 8.252~g/g in Lagos sole and croaker fishes respectively while in Delta, the

concentrations range from 6.969~g/g to 8.374~g/g in sole & 5.784~g/g to 6.401 ~g/g in croaker.

0.330 0.097,;." -i·i'-,,·~·.:,,-; ;·,;·,'-'''-'Y <;':;';~i:.:·:~:.;>.'::.·.;."." .,>,->.;

{'" '·';",':·'U"·-·' """":,.:"--,,,:,,,.-, e'··-·-···········v,-·,'····,'··._··· v:

10,987654321a

1::1PbSCdOCuOCrf!l Zn

this study corresponds with previous study (Eletta et aI., 2002). Lead is known to exert its most

significant effects on the nervous system, the hematopriotic system and the kidney. It has effects on

the nervous system including motor disturbances.

Cadmium concentrations are all higher than the EC, 2005 limit of 0.05 11gig except in Delta

croaker with a concentration of 0.029Ilglg. Cadmium concentrations in this study are higher than

those reported earlier in Edem et al., 2009. Adverse effects of excessive chronic cadmium exposure

may include; chronic renal failure, kidney stones, liver damage (rare), lung cancer, osteomalacia,

possibly hypertension, prostatic cancer, and proteinuria. Chronic cadmium exposure has been

reported to cause mild anemia, Skeletal Lessions, Itai-itai disease, anosmia, and yellowing of teeth.

Cadmium is a cumulative toxin. Its levels in the body increase over time because of its slow

elimination. It accumulates chiefly in the liver and kidneys. However, it also accumulates in muscle

and bone.

Chromium concentrations in this study are much more lower than previously reported in

Burgera & Gochfeld, 2005 but all values in this study were higher than the standard for chromium

0.730llg/g (IAEA-407). Haemolysis, resnal and liver failure, damage to circulatory and nerve

tissue, cancer, are some of the health effects of ingesting chromium at a concentrations higher than

the standard in the human body.

All the mean concentrations Zinc in this study were all lower than that of the standard of

3.28Oppm (IAEA-407). Zinc deficiency has been associated with dermatitis, anorexia, growth

retardation, poor wound healing, hypogonadism with impaired reproductive capacity,

Also, the study showed more heavy metals' pollution in Lagos lagoon fish samples than in

cocoa lagoon except in Zn where the concentrations in Delta were more than those of Lagos state.

The concentrations of Zinc were much lower than the tolerable values stated in the standard

5.0

CONCLUSION

CHAPTER FIVE

CONCLUSION AND RECOMMENDATION

In conclusion, fish samples from Lagos lagoon are more polluted than those from cocoa

lagoon of Delta states which could be attributed· to local point sources from industries in Lagos and

There is the possibilitY of chronic Cadmium & Chromium toxicity resulting from edible

fishes consumed in these states and this has serious implications on public health.

The result of this study could also establish a baseline for future studies of heavy metal

pollution.

5.2 RECOMMENDATION

l. There is a need for further extensive study and particularly the accumulation of heavy

metals in humans.

2. Point sources of heavy metals in the waters should be closely monitored & proper treatment

before disposal into water bodies should be enforced.

3. Continuous monitoring of these water bodies should be done in order to ensure that the

measures put in place to reduce the heavy metals concentrations in the fishes in Lagos and

Delta states is actually reduced.

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