EVALUATION OF HEAVY METAL

CONCENTRATIONS IN CANNED TUNA FISH SOLD IN

LAE CITY SUPERMARKET

A DISSERTATION

Submitted by

JOYCE MICHAEL

SUPERVISOR: MR. NARIMBI

In Partial Fulfillment of the Requirements for the

DEGREE OF BACHELOR OF SCIENCE

APPLIED CHEMISTRY SECTION

DEPARTMENT OF APPLIED SCIENCES

THE PAPUA NEW GUINEA UNIVERSITY OF TECHNOLOGY

SEPTEMBER 2016

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Acknowledgement

I would like to acknowledge the following hard working people who helped me carry out this

research.

Hazel Hecko (Bachelor of Science in Applied Chemistry Final Year Student)

Isadora Paleu (Bachelor of Science in Food Technology Third Year Student)

Julie Petrus (Bachelor of Science in Agriculture Third Year Student)

KaysiePuringi (Bachelor of Science in Applied Chemistry Final Year Student)

Anna Apio (Bachelor of Science in Applied Chemistry Final Year Student)

Philemon Miul (Post Graduate Applied Physics with Electronics & Instrumentation)

Mr. J Narimbi (Project Supervisor &Environmental Chemistry Lecturer)

Mr. Tata Telawika (UASL Laboratory Manager)

Mr. SoveraGuti (UASL Laboratory Technician)

Dr. Harakuwe (Instrumental Analysis III Lecturer)

These are the people who worked with me until the completion of the research project. Without

them I don’t think the research will be finalized like this in this manner. They helped in terms of

finance, data collection, instrumentation, and other things and therefore I thank them for their

participation and cooperation.

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Abstract

Inductively Coupled Plasma Optical Emission Spectrophotometer was used to analyze four

different varieties of canned tuna fish sold in Lae Supermarkets in which two are overseas

products and the other two are PNGs’ manufactured. Dry ashing method was employed in which

1:5 ratio HNO3/HCl reagent was used to bring the metal into solution before further analysis.

The world permissible limit set by EC, WHO and FAO was (0.05-0.5ppm and 0.4-0.5ppm) for

cadmium and lead respectively. The results obtained from the four different canned tuna fish was

found to be (0.0003-0.002ppm) and (0.0001-0.0008ppm) for cadmium and lead respectively

which was much lower than the permissible limit. Many other researchers carrying out similar

research in other countries also reported that the heavy metal content in canned tuna fish are

lower than the permissible limit by Mehdi Zarei et al., (2010), Pourjafar H et al., (2014) and

Mani Mahalakshmi et at., (2011).

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Glossary

AAS: Atomic Absorption Spectrometry method that are used for isolating element of interest.

There are all sorts of AAS and they can be used according to the sample type and the element of

interest.

Anthropogenic activities: Human activities that cause environmental pollution

AOAC Method: Association of Official Analytical Chemists method is a book that contains all

the standard laboratory methods that is used world-wide.

Bio-accumulation: The buildup of a substance in a living thing to a concentration that is greater

than the concentration of the substance in the natural environment.

Bio-magnification: Heavy metals concentration in the food chain getting bigger and bigger

from.

Desiccator: A laboratory equipment containing silica gel in it where it is used for cooling very

hot objects within short period of time without contaminating the sample in the object.

FAO: Food and Agricultural Organization

Heavy metal: An element that is poisonous even when present in low concentrations and is

hydrophobic in nature.

Hydrophobic: Hydrophobic elements are metals that do not easily react with water hence tend

to form emulsified solution. Hydrophilic is the opposite to hydrophobic where they easily react

with water.

ICP-OES: Inductively Coupled Plasma- Optical Emission Spectroscopy is a type of

spectrometry method that uses plasma for isolation of element of interest.

Leaching: Is the action of bringing the solid sample into solution using an appropriate leaching

agent

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Lixiviant: A reagent that is either a base or an acid that is used for extraction of element of

interest in a sample.

Muffle Furnace: A heating equipment used for drying and ashing samples at different

temperature ranges according to a standard procedure you applied to get samples dried or ashed.

Non-point source: Many sources of pollution those are non-identifiable.

Point source: Only one source of pollution that is identifiable

Reagent: Any upgraded acids and bases that are recommended for usage in the laboratory to

digest, titrate, and to analyze samples. Different samples uses different reagent according to the

AOAC standard method.

Sampling: Is the action of taking out a portion of something for analyses purpose.

WHO: World Health Organization.

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Table of Contents

Acknowledgement ................................................................................................................................... i

Abstract ...................................................................................................................................................... ii

Glossary .................................................................................................................................................... iii

CHAPTER ONE: INTRODUCTION ....................................................................................................... 1

1.1: Background .................................................................................................................................. 1

1.1.1: Heavy metals in the global contexts .............................................................................. 3

1.1.2. Heavy metals in PNG local contents .............................................................................. 4

1.2: Research Problem ...................................................................................................................... 5

1.3: Study Location ............................................................................................................................. 5

Figure 1.1: Map of PNG showing the highlighted Morobe Province...................................... 6

1.4: Research aim and specific objectives .................................................................................. 6

1.5: Research hypothesis.................................................................................................................. 6

1.6: Significance of the study ........................................................................................................... 7

1.7. Outcomes and Benefits ............................................................................................................. 7

1.8: Thesis Outline ............................................................................................................................... 7

CHAPTER TWO: BACKGROUND ........................................................................................................ 9

2.1: Introduction .................................................................................................................................. 9

2.2. Literature Review ...................................................................................................................... 10

2.3: Physical, geographical, and socio-economic description of the study environment

................................................................................................................................................................ 14

2.4: Detailed discussion of Heavy metals ................................................................................... 15

2.4.1 Causes and Effects of heavy metals in the body ....................................................... 16

2.4.2. Lead ....................................................................................................................................... 16

2.4.3. Cadmium .............................................................................................................................. 17

CHAPTER THREE: METHODOLOGY ................................................................................................ 19

3.1. Introduction ................................................................................................................................ 19

3.2: Method of Application .............................................................................................................. 19

3.2.1: Dry ashing method ............................................................................................................ 19

3.2.2: Purpose of method ............................................................................................................ 20

3.2.3: Scope or field of application ........................................................................................... 20

3.3: Reagents ...................................................................................................................................... 20

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3.3.1: Standards for ICP-OES .................................................................................................... 21

Figure 3: Standard formula for calculating the unknown concentration and volume ....... 21

3.4.1: Procedures: ......................................................................................................................... 21

3.5: Sampling ...................................................................................................................................... 22

Figure 3.2: Sample Preparation Chart .......................................................................................... 23

3.5.1: Dry-ashing Method ............................................................................................................ 23

Figure 3.3: Ratio of reagent used for sample preparation ...................................................... 24

Figure 3.4: General view of how Inductively Coupled Plasma-Optical Emission

Spectrophotometer (ICP-OES) normally work............................................................................ 25

3.7: Analytical quality assurance and control ........................................................................... 25

3.8: Data processing and analyses .............................................................................................. 26

CHAPTER FOUR: RESULTS ............................................................................................................... 27

4.1: Introduction ................................................................................................................................ 27

4.2: Results .......................................................................................................................................... 27

Table 4.1: Table showing results obtained from ICP-OES ....................................................... 27

4.3: Data analysis and statistical evaluation ............................................................................. 27

CHAPTER FIVE: DISCUSSION ........................................................................................................... 30

CHAPTER SIX: CONCLUSIONANDRECOMMENDATION ........................................................... 31

6.1: Conclusion................................................................................................................................... 31

6.2. Recommendations .................................................................................................................... 31

REFERENCES ......................................................................................................................................... 32

APPENDICES .......................................................................................................................................... 34

APPENDIX A: A MAP SHOWING MOROBE PROVINCE IN PAPUA NEW GUINEA. .................. 34

APPENDIX B: SHOWING HOW THE SAMPLE PREPARATION WAS DONE ............................... 34

APPENDIX C: SHOWING HOW THE ICP-OES WORKS .................................................................. 35

1

CHAPTER ONE: INTRODUCTION

1.1: Background

Heavy metals are naturally occurring elements that have high atomic weight and high density

that is of at least five times greater than that of the density of water (Tchounwou.et al., 2014).

There are multiple industrial, domestic, agricultural, medical and technological applications that

primarily aid to distribute heavy metals that destroy the natural environment. Government and

other concern citizen of this nation are raising concerns over the potential effects of heavy metals

in human’s life. The toxicity of these metals depends on several factors including the dose, route

of exposure and their chemical species (Janarthanan, 2014). Because of their high degree of

toxicity in the body, cadmium, lead, mercury, arsenic and chromium rank among the priority

metals that are of public health significance. These are the primary elements that make up the

Earth’s crust and cannot be naturally broken down into further simpler substances(Ahmed Q

&BatL, 2015)

Initially heavy metals naturally occur in the environment with other primary elements to create

new things and to sustain life on earth (Ahmed Q &BatL, 2015). It is via the natural and

anthropogenic activities that pollute the environment so badly that directly poison the living

tissue of an organism’s body system(AN. Sabramanian., 2009). Pollutants enter the aquatic

environment from two main types of sources. The anthropogenic activities which drastically

affect the environment are classified into point and non-point sources of pollution. Point source

pollution is a type of pollution that people can easily identify its origin. It is a single source for

example a sewage treatment or industrial tailings discarded into rivers or sea (Point Sources of

Pollution, n.d.) whereas a non-point sources of pollution refers to the type of pollution that is

caused by a combination of sources where it is non-identifiable. An example of a point source

pollution include pipe or a drain where industrial wastes are commonly discharged into the rivers

and seas (EPAV) whilst a non-point source is defined to mean any source of water pollution that

does not meet the legal definition of point sources like fog and smog (Non-point Sources of

Pollution, n.d.). Due to the above activities the water body became unhealthy for aquatic and

marine species to breed and reproduce easily.

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All edible substances on earth can become toxic to human body if their concentration is way

beyond the permissible limit. A few of these elements are poisonous even if present in a very low

concentration like cadmium which is very toxic at 0.05-0.5 ppm and lead at 0.4-0.5 ppm. These

are known as heavy metals. Examples of heavy metals include mercury (Hg), cadmium (Cd),

lead (Pb) arsenic (As), chromium (Cr), thallium (Tl), and aluminum (Al) (Lenntech, B.V., 2016).

Some of the heavy metals are considered essential to the body system like zinc (Zn), magnesium

(Mg), potassium (K), sodium (Na) and calcium (Ca). However, trace minerals including

selenium, iodine, boron and molybdenum became poisonous when present in excessive amount

in the body. For example zinc ion in the body can be easily replaced by the cadmium ion in the

DNA and RNA synthesis and can directly change the function of the enzyme in the body leading

to so many related body mal-functioning and diseases (Heavy Metal., 2016)

It is via natural and anthropogenic activities that aid to contribute more of the heavy metals onto

the aquatic environment (Lenntech, BV, 2016). Weathering processes easily brings and deposits

most of the heavy metals, pollutants, toxicants and hazardous substances into the open dynamic

system from their primary and secondary deposits (Pooter, 2013). Since the heavy metals are

quite dense they are able to sink into the ocean floor where the sediments are (Pooter, 2013). The

properties of metals dissolved in water depend largely upon the nature of metal species dissolved

in the water. Therefore, speciation of metals plays a crucial role in their environmental chemistry

in natural waters and wastewaters (Manahan, 2000).Most fishing industries use the large sizes

fish for fish products and when people consume most marine products it is assumed that they

tend to ingest higher doses of heavy metals of relatively high content depending on daily, weekly

and monthly intakes. Fish products are sold in bulk quantities compared to other fishmeal and the

demand is very high depending on those products daily consumed without paying close attention

to its side effects. It is primarily believed that the concentration of heavy metals in canned tuna

depends on the;

1. Sizes of raw fish (very large)

2. Life span (15-30 years)

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3. Distance travelled by tuna (44-62m/h)(Tuna Facts, 2016)

Due to the unique characteristics of tuna fish that draws the attention of researches to do more

research regarding heavy metal and the facts listed below have been abstracted out of the tuna

facts (Tuna Facts, 2016);

Larger in sizes

Tunas can travel large distances in a short period of time. It can pass across entire

Atlantic in 30 days by traveling 16 miles per hours

Despite their large size, tunas are very fast swimmers. They can reach the speed between

44 and 62 miles per hour.

Average life span of tuna is between 15 and 30 years in the wild. Small percent of tuna

managed to survive until this period.

Tuna can swim near the surface or can dive to the depth of 3000 feet while it searches for

food.

Tuna is a carnivore. It feeds on different types of fish (mackerel, herring, hake…), squids

and crustaceans.

This work is limited in its scope in that it only looks atonlyfour different types of canned tuna

fish commonly sold and consumed. Two products analyzed are manufactured from Indonesia

and Thailand while two are PNG manufactured.Unfortunately not all tuna products soldin Lae

supermarkets are analyzed. This is largely due to limiting factors such as time, finance and

analytical instrumentation.

1.1.1: Heavy metals in the global contexts

Tunas are usually located in temperate and sub-tropical waters of Atlantic Ocean, Mediterranean

and Black seas. Tunas are over-fished in different parts of the world, especially in Japan and

Australia (Tuna Facts, 2016). Due to large population and so many industries all across the globe

anthropogenic activities tend to contribute more pollutants into the natural environment. It

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directly pollutes the natural environment and alters its physical, biological, and chemical

properties of the natural system. “The sources of metal pollution come from manufacturing,

agriculture, sewerage treatment, industries, motor vehicle emissions, logging and mining

industrial sites” (Shazili, et, at 2007) .

The world outside is so industrialized and more developed where they emit and discharge so

many hazardous chemical as waste into the air and sea compared to PNG as one of the

developing country with little industrial activities, logging, agricultural farming, vehicle

emissions and sewage treatment. The leading infrastructural development in the world was Hong

Kong followed by Singapore and list continues. PNG doesn’t appear in the world statistical data

with respect to infrastructural development which signifies that PNG is the last with least

infrastructural development (The Statistics Portal, 2015).

1.1.2. Heavy metals in PNG local contents

PNG is a small country where there is but not limited to mining industries, agricultural farming

activities, waste sewage treatment, volcanoes and logging companies that pose environmental

pollution.

Purchasing and consumption of our own tuna fish products is much more safer than consuming

tuna fish products from other countries that are sold in Lae supermarkets. Since the outside world

is too industrialized they tend to contribute more pollutants to the sea compared to PNG as

mentioned in the (Statistics Portal, 2015) therefore it can be assumed that their tuna fish products

will contain higher heavy metal concentration than those tuna products produced here in PNG.

People most of the time people don’t consider the quality of the processed seafood but chose

according to the quantity and price to save money and to satisfy hunger. That is the main reason

of purchasing goods and services at the lowest and affordable prices. During the surveying the

researcher saw that tuna products normally ran out of stock faster compared to other canned fish

no matter what classes and type of people purchased the product.

Those canned tuna are of different varieties, processed in different canneries and so it is believed

that it contained different level concentration of heavy metals that is lead and cadmium

specifically that is harmful to the body at very low concentration.

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1.2: Research Problem

The consumption of fish and fisheries products have led to heavy metals toxicity issues in

humans especially the increased health risks in children and pregnant mothers around the world.

While many studies have been done elsewhere, there is no proper and adequate scientific data

available on the levels of heavy metals in canned tuna products sold and consumed in PNG

(March of Dimes, n.d). Therefore, there exists an urgent need to establish data on this important

issue to fill the missing gap in knowledge. Many health issues affecting mothers and children in

PNG have been linked to poor nutrition. The consumption of canned tuna fish products

containing elevated levels of heavy metals by these age categories could be a potential

confounding factor. Canned tuna fish in particular is an affordable source of protein and is

widely sold in major supermarkets and retail stores in Morobe and easily accessible to the

majority of middle-to-low income settlers in and around Lae city. It is perceived that the

increased consumption of these cheap and affordable canned tuna fish may have some

disadvantages which can easily lead to accumulation of heavy metals that can affect the

biological system of general population.

1.3: Study Location

The study will be conducted in Lae, Morobe Province. Since PNG University of technology is

located within Morobe Province so it is quite easy to conduct sampling within the vicinity of the

city. Furthermore Morobe Province is the second largest city in PNG that consists of so many

industries, schools and private business entities leading to high population. In such place that

caters so many people, their health and environment must be governed and protected. For this

reason the researcher thought it might be helpful to carry out such research here where there are

so many people and high demand for the same product every day. In such place, the possibility

of getting affected by heavy metal related diseases will be very high.

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Figure 1.1: Map of PNG showing the highlighted Morobe Province

1.4: Research aim and specific objectives

The overall research aim is to establish the cadmium (Cd) and lead (Pb) concentrations of canned

tuna fish sold in Lae supermarket. To achieve the overall aim of this research the following

specific objectives will be implemented.

1. To carry out sampling of canned tuna fish

2. To analyze canned tuna fish for cadmium (Cd) and lead (Pb) concentrations and

3. To evaluate compliance with international acceptable levels for these heavy metals

1.5: Research hypothesis

Heavy metal concentrations in canned tuna fish sold in Lae supermarkets is below internationally

permitted standard.

MorobeProvince,

Lae

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1.6: Significance of the study

This study will highlight the potential risk of heavy metal accumulation by consumers in Lae

city. This information is going to be important for raising awareness to people and encourage

educated decision making in consumer choices. Furthermore, the information generated from

this study will be a useful tool for decision makers and authorities in public health management.

1.7. Outcomes and Benefits

The outcome of the study is to;

Define heavy metals, their toxicity level, speciation and their health impacts,

The origin of Cd and Pb pollutants in the environment, their sources of pollution and the

chemical interaction between the pollutant and the environment and the possible impacts

in the life of aquatic biota.

How the heavy metals especially lead and cadmium enter tuna fish tissue and gets

accumulated.

How the heavy metals in the canned tuna fish enter human body tissues, gets

accumulated and causes disruption in the enzymatic activities that finally results in health

issues.

Justify as to why most people favor canned tuna over other brand of canned fish and

Finally give a clear conclusion on the concentration level of heavy metals in canned tuna

fish in PNG over Thailand, Solomon Island, Indonesia and Fiji.

1.8: Thesis Outline

Chapter one covers the introduction and will include the origin, nature, and sources of heavy

metals present in the environment and cause most of the pollution in the water system. It also

includes the research problem, its significance as to why it is under study, the study location, the

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objective of the research, the research hypothesis that forms the basis of the study and not

forgetting the outcome of the research that will be accomplished at the end of the research.

Chapter two contains the literature review on heavy metal concentration in canned fish that are

sold worldwide and the toxicity of lead and cadmium in the body whilst chapter three contains

the methodology of the research how the sample will be collected, prepared and the instrument

that will be applied during analysis process. Chapter four will cover the expected results. Chapter

five will discuss the expected results and chapter six will include the conclusion and

recommendation.

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CHAPTER TWO: BACKGROUND

2.1: Introduction

Fish meat may be contaminated from toxic metals during commercial transport and processing

depending on the raw material before processing occurs. Therefore, monitoring of these products

is important with respect to toxic elements affecting human health (Fathabad, Shariatifar, etal.,

2015). Heavy metals are considered the most important form of pollution of the aquatic

environment because of their toxicity and accumulation by marine organisms.Heavy metals

including arsenic (As), mercury (Hg), lead (Pb) and cadmium (Cd) are hydrophobic in nature and

have the ability to accumulate in the body tissues. On the other hand they have no beneficial

impacts in the body. While other elements such as chromium (Cr), copper (Cu), zinc (Zn), iron

(Fe), manganese (Mn) and other essential micronutrients are essential to the body when present

in lesser concentration but when present in higher concentration also tend to become toxic to the

body(Khansaria,b, Khansaria,*&Albdollahic., 2004).

Metal pollution of the sea is less visible and direct than other types of marine pollution but its

effects on marine ecosystems and humans are intense and very extensive. The toxic effects of

heavy metals, particularly arsenic, mercury, cadmium and lead, have been broadly studied

(Inskip&Piotrowsiki, 1985; Kurieshy&D_siliva, 1993; Narvaes, 2002; Nishihara, Shimamato,

Wen, & Kondo, 1985; Schoerder, 1965; Uchida, Hirakawa, & Inoue, 1961; Venugopal&Luckey,

1975).

Above information proves that there are many researchers carrying out research based on the

same topic. However, their aims and objectives are differently organized. Most cited literature

review collected and written in this research was done outside of the country excluding PNG

which includes Lae, Morobe Province. Therefore the main aim of this research was to determine

the concentrations of heavy metals particularly lead and cadmium in canned tuna fish sold in Lae

supermarkets.

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2.2. Literature Review

Heavy metals are considered as one of the most important form of pollutants present in the

aquatic environment because of their toxicity and accumulation by marine organisms. The main

exposure by humans to these heavy metals (Cd, and Pb) is via the ingestion of contaminated fish,

especially larger predators including tuna, marlin etc. While mercury, arsenic, cadmium and lead

can be tolerated at extremely low concentrations, they are extremely toxic to humans

(AgyekumAkwasiAkomeah, et al., 2012). Many researchers including both PNG and global had

published their papers by concluding that the natural environment is over polluted that all living

organism in aquatic, marine and terrestrial organism at least contain some heavy metals and it is

also confirmed in (UNADF, 2015, STD Toolkit, 2002, Papua New Guinea Environment

Monitor, 2002 and Quratulan Ahmed &Levent Bat, 2015). “The ingestion of food is an obvious

means of exposure to metals, not only because many metals are natural components of

foodstuffs, but also because of environmental contamination and contamination during

processing” (Voegborlo R.B et al, 1999).

There are many related heavy metal diseases arises recently that needs very close monitoring and

researches have done to prove the possible cause of the diseases. As mentioned earlier cadmium

and lead are very toxic to human in very low concentration and the related diseases that they

caused are very serious in which infants are most vulnerable. The EC, Food and Drug

Authorities (FDA), FAO and the World Health Organization had set the world permissible limit

of cadmium and lead to be (0.05-0.5 & 0.4-0.5ppm). Concentration above this limit can possibly

toxify the body.

Chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn), among other metals, are

essential micro-nutrients for humans involved in important biological processes. These elements

prevailingly plays functional and structural role in human body (Rivas, et al 2014). However,

there are no homeostatic mechanisms in the human body to eliminate elements, such as cadmium

(Cd), arsenic (As), mercury (Hg), and lead (Pb) which are classified as heavy metals have no

beneficial functions in human body (Ali-Mutarri 2015). The toxicity of the metals varies and it

also depends mostly on the concentrations at which a specific organism is exposed to. However,

long-term exposure of Hg, As, Cd, and Pb at relatively low levels can have deleterious effects on

11

human health. The European Food Safety Authority (EFSA) has provided evidence that exposure

to these contaminants can cause neurological, cardiovascular and reproductive disorders.

“Metal contamination in an aquatic system is a particular concern because metals are both

persistent and toxic” (Clark 1992). Most environmental pollutants initially came from industrial

waste around the countries and get more concentrated around the estuary and this statement

confirms with Galindo’s research stating that, “The Huelva estuary and the Tinto and Odiel

rivers which flow into it are all affected by discharges from industries and historic mining

activities locally”. The area, in which fishing is forbidden, is globally significant in terms of its

levels of heavy metal contamination. Mining sites may pose a unique risk because metal

concentrations in water at mines tend to be several orders of magnitude higher than those for

uncontaminated sites says Stuart M. Levit. “Metal-contaminated macro-invertebrates are likely

to then form a principal food component in the diet of bottom-dwelling fish, and these fish are

also likely to show increased metal uptake via the gut and directly across the gills. Cumulative

metals, such as cadmium,lead, mercury and arsenic, may be transferred to higher predatory fish

by the processes of bio-magnification.” (STD Toolkit, 2002).

In PNG there are not much anthropogenic activities being practiced compared to other well

industrialized counties. Heavy metal related diseases are more common nowadays. It can be

suspected that canned tuna fish must be a possible cause to it due to its bigger sizes, lived up to

10-30 years, can swim faster regardless of their weights and can even travel 44-62mph searching

for food that is stated in the (Tuna Facts, 2016). All these facts so far collected the researcher can

easily make justifications that tuna fish are eligible to contain more heavy metal than other fish

species. However, many researchers concluded their findings on heavy metal (Pb& Cd)

concentration to be lower than the permissible limit by (Khansari, Ghazi-Khansari&Abdollahi.,

2005 and Al-Mutarri, 2015.)

If the PNG marine environment is heavily polluted by the anthropogenic activities then the

consumer of the final product will be affected as badly as many canned tuna products sold in

Morobe supermarket are PNG made products except only a hand-full of it are of other countries.

However, due to the above reasons the researcher can easily justify by saying that the marine

environment around PNG is somewhat safer to catch tuna fish for production while seas in other

12

countries will be considered unsafe to catch fish for production. This is due to the frequent

application of anthropogenic activities that one way or the other contributes more to the marine

disaster as well as the unique characteristics of tuna fish.

Morobe seas will be safer since it rains a lot and the turbidity of river system and marine will be

able to undergo turbulence where the metals will sometimes form complex with other metals in

the water that cannot be easily broken and in that case some of the complex when consume by

the marine organism cannot be easily broken down by the enzymatic functions in them can easily

remove in the body as a waste. Since there are no literature based on something related to PNG

marine system about pollution free for fishing, this research is the first of its kind to either prove

or disprove the above assigned thesis.

Toxicological and environmental studies have prompted interest in the determination of toxic

elements in food. Cadmium and lead can be tolerated only at extremely low levels and at certain

concentrations they are exceptionally toxic to humans (Voegborlo, 1999).Fish is widely

consumed in many parts of the world because it has high protein content, low saturated fat and

also contains omega fatty acids known to support good health (Ikem and Egiebor, 2005). But

also contain toxic substances hidden in them which are microscopic and cannot be seen with the

negative eyes but can detect through atomic absorption spectrometer (AAS) where very minute

contaminants can be easily detected in parts per million. The distribution of metals varies

between fish species development status and other physiological factors (Kagi and Schaffer,

1998). The effects of these elements on human health have also been widely reported (Lall,

1995; Linder and Hazegh-Azam, 1996; Munoz-Olivas and Camara, 2001).

“China is the world’s number one fish consumer and has the world’s largest fishing industry;

accounting for the third of the world’s catch therefore minamata disease is common in China.

This is followed in order by Peru, Japan, the US, Chile, Indonesia, Russia, India, Thailand,

Norway and Iceland” (Encyclopedia, 2011). However the tuna cans sold in Morobe supermarket

are all imported from Indonesia, Fiji, Thailand and Solomon Island. Hence PNG made products

are also sold in bulk quantities in Morobe compared to Thailand’s, Fijis, Indonesia and Solomon

Island’s manufactures. “Although Peru is number two in the world for catching fish, Peruvians

eat hardly any of this and it is exported. On the other hand, fish is so popular in Japan that

13

although at number two in the catching list, Japan has to buy has much again from other

countries in order to meet the domestic demand” (Encyclopedia, 2011).

Regina Asiad, a representative of the Lihir village planning committee, says that a few years ago,

dugout canoes “overflowing” with fish arrived daily at Lihir’s wharf. “Now you might get five or

six fish in a boat, or absolutely nothing. Strange things happen that we never encountered before.

We find dead fish, and sometimes fish we catch taste strange so people won’t eat it. A lot of pigs

died after eating stuff on the beach. We wonder about that mine.”(Regina A, 2002). If that’s the

case then it is expected to see a lot of deaths occurring in PNG but that doesn’t happened maybe

because this province experiences too much rainfall per annum that can easily have effects on the

aquatic and marine forming oxidation and complexation reaction that the heavy metals from

toxic species to non-toxic species by undergoing the above mentioned reactions. And also tuna

fish are type of fish that travels long distances and by doing so they can be able to move away

from feeding on contaminated small fish. Turbulence arise from the flood can cause pH to

change automatically that can also affect the formation of toxic heavy metal species. Small

creeks around the mine sites where waste sometimes drops in are caught by the ferns on the river

side which help to reduce the concentration of heavy metals before reaching the sea.

Many studies have proved that heavy metals such as lead and cadmium in canned tuna fish have

lots of impacts in human body. Therefore this reason has form the basis of this research that the

researcher tries to identify the particular type of tuna cans accumulates more heavy metals and

which country of manufacturing will possibly cause problems and can find other alternative way

to solve the arising issue rather than being ignorant.

With all these fact analysed above drives researchers to find out the heavy metal concentration in

canned tuna fish and that is why Mehdi Zarei et al., (2010) was carrying out a similar research on

heavy metals in canned tuna fish sold in Iran to see if the five major sold canned tuna fish are the

possible cause of the very severe diseases however they reported that the concentration of

cadmium and lead in the canned tuna fish are (0.002-0.07 μg/g and 0.007-0.51 μg/g)

respectively. The concentration shows that the canned tuna fish sold at Iran are safer for

consumption since the concentrations reported are lower than the permissible limit.

14

There was another similar research type done in 2011 by other Boadi N.O. et al in Ghana. Their

research also proves that the nine different types of canned tuna fish sold in Ghana shows that

their concentration level also lies below the allowable limit required. Thought in 2010 results

shows above there must be some differences in 2011 but the results remain constant.

Pourjafar H et al., (2014) on the similar topic from the same capital Tabriz (Iran) trying to

disprove Mehdi Zarei et al., (2010) &Baodi N.O et al., (2011) results by analyzing five different

types of canned tuna fish, however their results also lies somewhere below the world permissible

limit which is (0.01-0.242 ppm) for lead and cadmium lies below the detection limit. Again in

the same year (2011) Mani Mahalakshmi et al was carry out another similar type of research

done using processed canned tuna fish from Canada and India in which Canadian products are

used to analyze mercury and aluminium while Indian products are used to analyze cadmium and

lead. The results reported are below world required standard in the case of cadmium and lead but

for aluminum and mercury are higher therefore they concluded by saying that “canned tuna must

be monitored comprehensively and periodically with respect to the consumer health”.

Extremely all researchers carrying out similar research on this topic seemed to obtained results

with concentration below the world permissible limit. Since there are no available data on recent

studies this researcher tried to determine the concentration of heavy metals in canned tuna for

this year (2016) to see if there are any significant changes in the concentration level.

2.3: Physical, geographical, and socio-economic description of the study

environment

Estimation of about eighty per cent (80%) of people living in Lae city are unemployed and only

twenty per cent (20%) are employed. Due to the fact that most Morobeans are unemployed, the

economic value is too highly demanded, so the people will try to manage from the little they earn

to satisfy their daily basic needs. Sometimes people oversight and forgot to consider the quality

of the product and only choose according to its quantity. For this reason the customers go for the

products that are of most cheap and affordable prices to satisfy their daily needs and wants. It is

via this reason that most people chose tuna canned fish among all the canned fish products. This

is the main reason of Raumai 18 wholesale store at Eriku normally orders canned tuna fish in

bulk quantity than other brands of canned fish like sardine and mackerel due to the stock being

15

running out so quickly. It is scientifically believed that the more you consume contaminated

products, the more heavy metal you accumulate in the body and the more you destroy your own

body system to function well so people have to think twice and choose wisely before you regret.

2.4: Detailed discussion of Heavy metals

“Elements are the basic building blocks of all chemical compounds, and human exposure to them

occurs both from natural and anthropogenic sources” (Doctors Data Inc, 2016). Many elements

are considered nutritional and are essential for the proper functioning of the body. These are

generally divided between macro-minerals such as calcium (Ca), magnesium (Mg), potassium

(K), sodium (Na) and zinc (Zn), while trace minerals including selenium (Se), iodine (I), boron

(B) and molybdenum (Mo). However, their tendency of becoming toxic is also very high when

the body gets in excessive amount of those into the body which Lawrence Wilson has agreed by

stating in his research under toxic metals and detoxification saying that “Also, some forms of the

required minerals can be highly toxic. For examples are some forms of copper, iron, manganese,

hexavalent chromium selenium and others. Sometimes too much of those essential minerals can

also be toxic.

Conversely, there are a number of elements that are toxic to the human body, interfere with its

functioning and undermine health such as mercury (Hg), lead (Pb), cadmium (Cd), chromium

(Cr), and arsenic (As). These toxic metals have no known physiological functions in the human

tissue. They can be toxic to organ systems and may disrupt the balance of essential nutrients.

Toxic metals and essential element status can be assessed in urine, blood, feces and hair (Doctors

Data Inc, 2016).

A toxic substance is a chemical that is harmful for people or other living organisms. The effects

from exposure to a toxic substance may be acute or chronic. Acute effects are those that appear

shortly after exposure, usually to a larger concentration or doses over a short period of time.

Examples of acute effects are skin burns or rashes, eye irritation, chest pains, kidney damage,

head ache, convulsions, loss of appetite, and then finally death. Effects that are usually long-

lasting are called chronic effects. They may not appear for months to years after exposure and

usually last for years. Examples of chronic effects are cancers, lung and heart disease, birth

defects, genetic defects and nerve and behavioral disorders. Chronic effects often occur as a

16

result of prolonged exposure to fairly low concentrations or doses of a toxin in which prolonged

exposure to heavy metals results in chronic effects (Janarthana, 2015). In general, toxic

chemicals like heavy metals attack the active sites of enzymes inhibiting the essential enzyme

function because they have no useful function in the body. Heavy metal ions, in particular

(Pb2+& Cd2+) act as effective enzyme inhibitors. They have affinity for Sulphur containing

ligands. For example SCH3 and –SH in methionine and cysteine amino acids, which are part of

the enzyme structure. Pb and Cd are soft Lewis acids and so they love to bond with soft Lewis

bases like sulfhydryl linkage of cysteine residue. Normally, cysteine residues provide structurally

important cross-linking sites through the formation of disulphide bridges. Heavy metals interfere

with formation of such bridges (Janarthanan, 2015).

Metalloenzymes contain metals in their structure and their action is inhibited when one metal ion

of a metalloenzyme is replaced by another metal ion of similar size and charge. Thus Zn (II) in

some metalloenzymes is substituted by Cd (II) which leads to Cadmium toxicity. The enzyme

inhibited by Cd (II) includes adenosine triphosphate, alcohol dehydrogenase, carbonic anhydrase

and many more. Pb (II) inhibits acetylchoanesterase and some of the key enzymes in the

synthesis of hemoglobin (Janarthanan, 2015).

2.4.1 Causes and Effects of heavy metals in the body

Since they are harmful to the body in very low concentration, they eventually get accumulated in

the body since they don’t metabolize so easily. Lead present in the body causes mental

confusion, visual disturbances, convulsions, loss of cognitive abilities, anti-social behavior,

paralysis, anorexia, “lead line" on gum margin, nausea, vomiting, severe abdominal pain and

anemia while the presence of cadmium in the body causes extreme restlessness and irritability,

headache, chest pain, increased salivation, choking, vomiting, abdominal pain, diarrhea,

tenesmus, throat dryness, cough, pneumonitis (Janarthanan, 2015).

2.4.2. Lead

“Lead in the environment is mainly particulate bound with relatively low mobility and

bioavailability. Lead does, in general, not bio-accumulate and there is no increase in

concentration of the metal in food chains” (Heavy metal in waste, 2002).

17

Lead can cause disruption of heme synthesis leading to lack of utilization of oxygen and glucose

for life sustaining processes. A higher level of lead in blood leads to loss of appetite, anemia,

kidney malfunction, nervous disorder (Pb is neurotoxin) and brain damage. At intermediate

concentrations, however there is persuasive evidence that lead can have small subtle, subclinical

effects, particularly on neuro-physiological developmental in children.

The overall effect is the disruption of heme synthesis of hemoglobin as well as other respiratory

pigments, such as cytochromes which requires heme. Finally lead does not permit utilization of

oxygen and glucose for life sustaining energy production. This effect can be detected at high

level of ~0.3 ppm in the blood. At higher levels of lead in the blood (0.5-0.8 ppm), there will be

symptoms of anemia due to the deficiency of haemoglobin. Elevated Pb levels (>0.8) ppm in the

blood cause kidney dysfunction and finally brain damage.

Due to chemical analogy between Pb (II) and Ca (II), bones act as repositories for lead

accumulated by the body. Subsequently, this lead may be remobilized along with phosphates

from the bones which exert a toxic effect when transported to soft tissues (Janarthana, 2015).

Lead poisoning will be cured by feeding the patient with an aqueous solution of calcium

complex of EDTA. Below is a general equation showing the formation of EDTA complex with

Pb.

Ca-EDTA (Soluble) + Pb2+

= Pb-EDTA (soluble) + Ca2+

2.4.3. Cadmium

Cadmium occurs in nature in association to zinc minerals. Cadmium appears just next to zinc in

the periodic table and their shell structure is somewhat same therefore cadmium can easily

replace zinc when there is lack of zinc. The outbreak of cadmium poisoning occurred in Japan in

the form of itai-itai or “ouch ouch” disease is a type of disease where bones become fragile. At

high levels, Cd causes kidney malfunction, anemia and bone marrow disorders. The major

portion of cadmium ingested into our body is trapped in the kidneys and eliminated. It can be

able to live in the body over years. A small fraction is bound most effectively by the body

proteins, metallothipnein present in the kidneys, while the rest is stored in the body and gradually

accumulates with age. When excessive amounts of Cd (II) are ingested, it replaces Zn (II) at key

18

enzymatic sites, causing metabolic disorders (Janarthanan, 2015) then separated by one. There

are three technologies applicable for removing Cd from industrial waste waters. In waste water,

dissolved Cd can be either precipitated with sodium sulphide or it can be cemented by the

addition of zinc or separated out by ion exchange. If the cadmium is incorporated into

particulates, the Cd can be dissolved by the addition of acid and of the below techniques or the

solids can be settled out and the cadmium removed with the sludge.

1. CdCl+(Chloro complex I sea water) + HS- =CdS(s) + H+ + Cl-

2. Cd2+

(aq) + Na2S = CdS(s)

3. Cd2+

(aq) + Zn(s) = Cd(s) + Zn2+

(aq)

4. Cd2+

(aq) + Na2[RESIN] = Cd[RESIN]2 + 2Na+ (aq)

19

CHAPTER THREE: METHODOLOGY

3.1. Introduction

Dryashing is a method that was applicable for the determination of cadmium and lead in canned

tuna fish. It has been reported that the major drawback to dry ashing is loss of metal due to

volatilization. However, the temperature in the muffle furnace was held at 500˚C, loss from

volatilization is minimal. The dry-ashing method was simple and less time consuming than the

digestion methods. The level of cadmium and lead are too low to be determined directly, solvent

extraction was applied to concentrate these elements.

Prior to that, sampling of all canned tuna fish are done, transported into the laboratory opened

and homogenized via a food blender and got preserved in the freezer below zero degree Celsius

to avoid contamination of the sample to preserve the analytes of interest for metal recovery.

Sample preparation was considered the most significant method employed in all the laboratories

around the world to bring the sample to its appropriate sizes prior to any analysis (“AOAC,”

1988). Analytical quality controls and assurance are applied to the sample along the process to

increase accuracy and precision of the analysis to obtain results of validity. Reagents of high

purity are employed to preserve samples of different types accordingly. Muffle furnace was

applied to obtain dry weight and also for ashing, nitric acid was applied to the sample to obtain

carbon-free ash and hydro-chloric acid was added to concentrate the analyte of interest. In this

section, temperature, pressure and time are the most significant parameters that are closely

monitored to valid the results of the analysis.

3.2: Method of Application

3.2.1: Dry ashing method

To determine bio-metals in biological animal and plant tissues. However in this research, the

method was applicable for the determination of bio-metals in fish tissues in the canned tuna fish

products especially the heavy metals such as Pb and Cd. This method was extracted out of the

20

AOAC standard method that has been recently applied and used by the Unitech Analytical

Services Laboratory (UASL).

3.2.2: Purpose of method

This method describes the procedures for the determination of levels of nutritional and toxic

elements commonly analyzed in tissues except for C, N, Si and Cl. The procedure was applicable

for samples of both animal and plant origin.

3.2.3: Scope or field of application

The samples homogenized via food blender and are stored in polyethylene containers in the

freezer. This was done to preserve the analyte so as the sample from contamination. Muffle

furnace are used primarily to obtain dry weight, nitric acid are applied to volatilize off all other

metals present in the test sample and to obtain carbon-free ash, and to concentrate the analyte

using nitric acid digestion. The samples are weighed and dried at 137OC

in the muffle furnace and

controlling the time. Digested on a hot plate to obtain carbon-free ash repeat until a carbon-free

ash is obtained using nitric acid. One normality of Hydro-chloric acid was used to concentrate

the analyte of interest and dilute to mark in a 25ml volumetric flask for analysis via ICP-OES.

3.3: Reagents

Analytical reagent grade are used.

30% Ethanol (Rinsing blender)

Concentrated nitric acid (digest)

1N hydro-chloric acid (concentrating analyte)

Distilled water(dilution).

21

3.3.1: Standards for ICP-OES

An extract of standard stock solution of Pb and Cd (1000mg/L) was pipetted into 25ml

volumetric flask to prepare secondary standard. Out of the secondary standards was prepared the

working standards in which the secondary standards are spiked with Nitric depending on the type

of stock standard used prior. Finally working standards are prepared out of the secondary

standards that was used to analyse via ICP-OES. The standards will be prepared using the

standard formula;

Figure 3: Standard formula for calculating the unknown concentration and volume

3.4. Sampling Equipment Preparation

Sampling equipment are the master key player in this research since they provide

accommodation for the analyte of interest which are the heavy metals and also act as a protecting

agent for any form of contamination, spillage, deterioration and exposure to atmospheric

contaminants. The sampling equipment are washed thoroughly with soap and 10% nitric acid to

fully sterilize all the necessary equipment for sampling and analysis and this was the standard

procedure normally applied before using a lab apparatus.

3.4.1: Procedures:

Soak the necessary equipment in the sink or big containers with water for approximately

two days foe easy washing.

Appropriate lab detergent was used for washing to further remove dirt and other

additional contaminants and bacteria for clean apparatus for usage.

Air-dried the equipment and apparatus on the bench top to dryness.

Standard Formula

M1V

1 = M

2V

2

22

Soaked them again into another container containing 10% nitric acid for all other

equipment but soak the ICP-tubes in a separate bowl containing 10% hydrochloric acid to

purify the equipment thoroughly to remove all the unwanted chemicals and pollutants to

contaminate the sample while preparing and processing. Finally a final rinse with de-

ionized water and air-dry to evaporate of the water on the bench top ready for usage.

3.5: Sampling

Sample collection was done by the technical staffs. A duplicate of three canned tuna fish each

was bought with respect to the country of production and the manufacturing company. Actually

there was no need for observation to be done onsite since the samples are being packed and

ready for sample preparation and via ICP-OES.

3.6: Sample Preparation

Labels removed

Sample identification given to each brand.

Opened canned tuna fish via fish opener.

Homogenize via food blender

Stored in polyethylene containers with lids carefully closed. Every after blending one

brand the blender was rinsed with 30% ethanol.

Stored in freezer below zero degree Celsius.

25g of wet weight was gently weighed into porcelain crucible and placed into muffle

furnace with a blank as the control without replicates due to the size of furnace and time

limitation and timed it for two hours after reaching 137°© .

Dry weight obtained after being removed from muffle furnace and cooled in desiccator.

The porcelain crucible were again placed back into the muffle furnace increased the

temperature to 500°© for overnight ash to obtain carbon free ash.

23

The crucibles were removed cooled in desiccators and add 2mls concentration HNO3,

stirred carefully and placed them on the hotplate just to dryness.

Again the crucibles are then inserted back into the muffle furnace, raise the temperature

to 500°© for exactly 2hours to obtain white clear precipitates.

Gently the crucibles are removed let cooled to room temperature in the desiccators.

Finally 10mls of HCl was added to concentrate the solution and then was transferred in

the 25ml volumetric flask. The digest was then diluted to mark and sent into the

instrument room for analyses via ICP-OES.

Figure 3.2: Sample Preparation Chart

3.5.1: Dry-ashing Method

For each sample approximately 25g (wet weight) of homogenized fish tissue was weighed

accurately into four porcelain crucible in which each porcelain contain tissues of different brand

24

name with only one blank without any replicates nor reference material due to time limitation

and the size of muffle furnace. Placed in the muffle furnace and slowly raise temperature to

137°© for two hours to obtain dry weight for calculation. Removed and cooled in the desiccator

to room temperature and then placed it into the cooled muffle furnace again and raise the

temperature to 500°© doing overnight ash after the dry weight was obtained. Removed and

cooled to room temperature in the desiccator and add gently into 2mls of Con. HNO3 to obtain

carbon free ash and again the crucibles are then placed back into the muffle furnace after being

dried on the hotplate for 2 hours at 500°©. Removed and cooled to room temperature in the

desiccator. Again 10mls of HCl was gently pipetted into the porcelain crucible to concentrate the

digest. Placed on the hotplate to dissolve the white precipitates formed in the crucible to get into

the solution. The digest was then diluted with de-ionized water into a 25ml volumetric flask

ready for ICP-OES run.

Figure 3.3: Ratio of reagent used for sample preparation

3.6: Inductively Coupled Plasma-Optical Emission Spectrophotometer (ICP-OES) Analysis

After the dilution, the sample was sent over to the Unitech Analytical Services Laboratory

(UASL) for analyses via ICP-OES. Before that the instrument was calibrated using upper and

lower ranges working standards however, since lead and cadmium concentrations are lower,

standards prepared are between 0.1ppm to 10ppm.After the calibration the samples are detected

at their own characteristic wavelength in which the results are sent to the computer and data was

collected, calculations done on the collected data and was reported as parts per million (ppm).

Reagent

Conc. HNO3 :1N HCl

1:5 ratio

25

Figure 3.4: General view of how Inductively Coupled Plasma-Optical Emission

Spectrophotometer (ICP-OES) normally work

3.7: Analytical quality assurance and control

Both the quality control and quality assurance are often treated as the same but they are not.

Quality controls are measures that are used in the field sampling as well as analysis in the

laboratories while quality assurance are the assured actions with caution applied in handling the

problem to solve it with high quality.

In this research there are no field sampling applicable due to samples being already packed and

ready for transportation to the laboratory. In that case the analytical quality control and quality

assurance technique were applicable in the laboratory during sample preparation and analysis in

which only a blank was employed leaving out replicates and reference material due to so many

factors. The preparation are done in a clean condition with care and caution to avoid sample

contamination.

26

3.8: Data processing and analyses

Data processing and analysis was done automatically in the computer attached to the ICP-OES

instrument and the calculations of each results are done manually on Microsoft excel in tabulated

form following the standard format set that is applicable nation-wide.

27

CHAPTER FOUR: RESULTS

4.1: Introduction

This research was specifically carried out to compare the concentration of cadmium and lead in

canned tuna fish consumed by the people living within Morobe Province. In order to prove the

above stated theory of the research, the researcher was collecting test samples of canned tuna fish

of four different processing canneries in which two are of PNG and other two from overseas.

4.2: Results

Table 4.1: Table showing results obtained from ICP-OES

Sample Weight (g) Vol (ml) Cadmium (mg/L) Lead (mg/L)

25.036 25 1.37 0.366

25.078 25 0.371 0.138

25.253 25 2.24 0.477

25.161 25 2.27 0.786

4.3: Data analysis and statistical evaluation

A. Cadmium in canned tuna fish of four different brand types;

1. 1.37/25.036 X 25/1000

0.001µg/g

2. 0.371/25.078 X 25/1000

0.0003µg/g

3. 2.24/25.253 X 25/1000

28

0.002µg/g

4. 2.27/25.161 X 25/1000

0.002µg/g

The calculations shows that the cadmium concentration in canned tuna fish is lower than the

world permissible limit which is 0.05-0.5ppm.

The average level of cadmium concentration is calculated below:

(0.01) + (0.0003) + (0.002) + (0.002) = (0.0053)

(0.0053) ÷ (4) = (0.001325)

Mean = 0.001325

Range = 0.0003 – 0.002ppm of Cd in canned tuna fish

B. Lead in canned tuna fish of four different brand type;

1. 0.366/25.036 X 25/1000

0.0004µg/g

2. 0.138/25.078 X 25/1000

0.0001µg/g

3. 0.477/25.253 X 25/1000

0.0005µg/g

4. 0.786/25.161 X 25/1000

0.0008µg/g

29

The calculations shows that the lead concentration in canned tuna fish is lower than the world

permissible limit which is 0.4-0.5ppm.

The average level of cadmium concentration is calculated below:

(0.0004) + (0.0001) + (0.0005) + (0.0008) = (0.0018)

(0.0018) ÷ (4) = (0.00045)

Mean = 0.00045ppm

Range = 0.0001 – 0.0008ppmPb in canned tuna fish

30

CHAPTER FIVE: DISCUSSION

The hypothesis of this research states that the heavy metal concentration in the canned tuna fish

caught and processed in PNG is lower than the permitted concentration of heavy metals required by

the body compared to tuna products from other countries. This is has been disproved by saying that

all canned tuna regardless of the production site and the brand type contained lower concentration of

cadmium and lead which are much more lower than the FAO/WHO standard permitted limit.

All other researchers elsewhere carrying out similar research also proved that the heavy metal

concentration in the canned tuna fish are lower than the world permissible “Mehdi Zarei et al.,

(2010), Pourjafar H et al., (2014), Mani Mahalakshmi et at., (2011)

31

CHAPTER SIX: CONCLUSIONANDRECOMMENDATION

6.1: Conclusion

It can’t be concluded that all canned tuna fish sold in Morobe supermarkets are safe for human

consumption because there are only four types that were analysed. It can only be concluded directly

whether safe or not when all canned tuna fish sold in Lae supermarkets are analysed with controls.

However, when comparing all the related results obtained from other researchers, this research

tend to agree with other researchers saying that despite the fact of tuna it is safe for consumption

in which it has been scientifically proven that they are safe and good protein for body

development since results are well below the permissible limit which are (0.4-0.5 & 0.05-

0.5ppm) for lead and cadmium respectively.

6.2. Recommendations

I would suggest further research on this particular topic to prove that this results are

accurate since there are so many issues on heavy metals affecting people nowadays.

32

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APPENDICES

APPENDIX A: A MAP SHOWING MOROBE PROVINCE IN PAPUA NEW GUINEA.

APPENDIX B: SHOWING HOW THE SAMPLE PREPARATION WAS DONE

35

APPENDIX C: SHOWING HOW THE ICP-OES WORKS