ABSTRACT
Concentrations of 16 priority polycyclic Aromatic Hydrocarbons (PAHs) were determined in
30 brands of Nigerian and imported pastas in Nigerian market. The pasta samples were
categorised into (1) noodles (2) spaghetti and (3) macaroni. Analysis were performed by GC
– MS after soxhlet extraction of the sample and clean up of the extract. The concentration of
Σ16 PAHs in both the Nigerian and imported brands are in the range of 0.009 to 0.8 mgkg-1
and 0.002 to 0.007 mgkg-1 respectively. The Bap concentrations in 75% of the Nigerian
samples were less than 0.001mgkg-1 permissible limit specified for processed cereal based
food while all the brands of imported samples were below the maximum limit. The
concentrations of Σ8 carcinogenic PAHs in both the Nigerian and imported brands ranged
from 0.001 to 0.01 mgkg-1 and 0.001 to 0.004 mgkg-1 respectively. The Margin of Exposure
based on PAH8 as an indicator for the occurrence and effects of PAHs in food for generally
exposed individuals were less than 10,000 in 25% and 0% for child and Adult scenarios
respectively for Nigerian brands. For typically exposed individuals, it were 38% and 0% for
child and Adult scenarios respectively. For imported brands of pastas, the MOE values were
far higher than 10,000 for generally and typically exposed individuals in both child and Adult
cases. The MOE values indicate serious concern particularly for children who are consumers
of Nigerian brands.
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TABLE OF CONTENTS
Title Page – – – – – – – – – – – i
Certification – – – – – – – – – – – ii
Approval Page- – – – – – – – – – iii
Dedication – – – – – – – – – – – iv
Acknowledgement- – – – – – – – – – v
Abstract – – – – – – – – – – vi
Table of Contents- – – – – – – – – – vii
CHAPTER ONE
BACKGROUND
1.1 Introduction – – – – – – – – – 1
1.2 General Objectives – – – – – – – – 5
1.3 Specific Objectives – – – – – – – – 5
1.4 Statement of the Problem – – – – – – – – 6
1.5 Significance of the Study – – – – – – – 7
1.6 Scope of the Study – – – – – – – – 7
CHAPTER TWO
LITERATURE REVIEW
2.1 PAHs in Food – – – – – – – – – 8
2.2 Polycyclic Aromatic Hydrocarbons (PAHs) – – – – – 10
2.3 Formation of PAHs – – – – – – – – – 11
2.4 Sources And Environmental Fate Of PAHs – – – – – 11
2.5 Estimates of non-dietary exposure to PAHs. – – – – – 13
2.5.1 Smoking – – – – – – – – – 13
2.5.2 Occupational Exposure – – – – – – – – 14
2.5.3. Ambient Air – – – – – – – – – 14
2.6 Hazard Identification and Characterization – – – – – 14
2.6.1. Carcinogenicity – – – – – – – – – 14
2.6.2 Distribution – – – – – – – – – – 15
2.6.3 Absorption – – – – – – – – – 15
2.7 The Manufacturing Process of Making Pasta – – – – 16
2.8 The Health Benefits of Pasta – – – – – – – 20
CHAPTER THREE
MATERIALS AND METHODS
3.1 Sample Collection and Preparation – – – – – – 22
3.2 Samples Extracxtion and Clean Up – – – – – – 25
3.3 Estimation of Dietary Intake/ Risk Assessment – – – – 25
3.4 Chemical and Materials – – – – – – – 26
3.4.1 Gas Chromatography- Mass spectrometry conditions – – – 27
3.5 Quality Assurance – – – – – – – – 28
viii
3.5.1 Limit of Detection (LOD) and limit of Quantification (LOQ) – – 28
3.6 Statistical Analysis – – – – – – – – 29
CHAPTER FOUR
RESULTS AND DISCUSSION
4.1 Recovery Analysis – – – – – – – – 30
4.2 Concentration of PAHs in Nigerian and Imported Pastas – – – 31
4.3 Chemometric Data Analysis- – – – – – – – 35
4.3.1 Anova Analysis – – – – – – – – 35
4.3.2 Correlation / Principal Component Analysis (PCA) – – – 35
4.4 Bar Charts showing the concentrations of PAHs in Pastas – – 43
4.5 Estimation of daily intake and risk Assessment – – – – 45
4.5.1 Estimation of daily intake and risk assessment for Nigerian Pastas – – 45
4.5.2 Estimation of daily intake and risk Assessment for Imported Pastas – 53
4.6 Assumptions and limitations of this study – – – – – – 58
4.7 Conclusion and Recommendations – – – – – – – 59
4.7.1 Conclusion – – – – – – – – – – 59
4.7.2 Recommmendation – – – – – – – – 60
REFERENCES – – – – – – – – – 62
APPENDICES – – – – – – – – – 68
1
CHAPTER ONE
BACKGROUND
1.1 INTRODUCTION
The introduction and distribution of man-made compounds or excessive amount of natural
compounds have created avenue to understanding the effects of polycyclic aromatic
hydrocarbons on humans and the environment. It is therefore, necessary to study the effects
on individuals to population, communities and environments. The contamination of food by
chemical hazards is a worldwide public health concern. Among organic contaminants,
polycyclic aromatic hydrocarbons (PAHs) represent an important class of food
contaminants.1
Food can be contaminated from environmental source, industrial food processing and certain
home food preparation.2 – 4 Humans are exposed to PAHs by various pathways. For nonsmokers,
the major route of exposure is consumption of food and it contributes to more than
90% of total PAHs exposures of the general pollution in various countries.5 – 7 Food
contamination may also occur during periods of atmospheric pollution in which PAHs are
deposited on seeds, fruits or vegetables, which are then consumed.7 – 9 Many studies have
shown that cereals, vegetables10, oil and fat11 – 12 are the main contributors to the ingestion of
PAHs. However, grilled or smoked fishes and meats show a relatively low contribution,
except in specific cases or due to socio- cultural reasons that cause these foods to occupy a
prominent place in the diet.7, 13- 14
Over the years, different sources of PAH contamination of food have been found. Food items
and products could be contaminated by soils, polluted air and water.15 Some aquatic food
2
products, such as fish, can be exposed to PAHs present in water and sediments and the PAH
content greatly depend on the ability of the aquatic organisms to metabolize them.16
Furthermore, in the food processing industry, food additives such as smoke flavouring
products (SFP), lubricants, solvents, propellants, glazing agents and protective coating
contribute to contamination of food items by PAHs.17
The occurrence of PAHs in human foods reflects the conditions of the environment and
consequences of some thermal treatments that are used during the preparation and
manufacture of foods.66 The amounts and types of polycyclic aromatic hydrocarbon
compounds generated during thermal processing of foods depend on the temperature, oxygen
availability, fuel type used, treatment duration, fat content and distance from the energy
source.57 In areas remote from urban or industrial activities, the levels of PAHs found in
unprocessed foods reflect the background contamination, which originates from long
distance airborne transportation of contaminated particles and natural emission from
volcanoes and forest fires. In the neighborhood of industrial areas or along highways, the
contamination of vegetation can be ten-fold higher than in rural areas.18
In general, PAHs are not present individually but in mixtures. Sixteen PAHs that have be
extensively monitored are the compounds included in the United States Environmental
Protection Agency (USEPA) list of priority organic pollutants.19 The 16 compounds are
given in Table 1 along with their abbreviation, molecular weight, Chemical abstract service
(CAS) number and structure. Of these 16 PAHs, Benzo [a] Pyrene (BaP) is probably the
most studied and has been widely used in environmental analysis as marker for the entire
PAH content.5
3
Different approaches have been proposed for the assessment of the risk of PAH mixtures in
human foods which include the use of Benzo [a] Pyrene as a maker, the toxic equivalency
factor (TEF), margin of exposure (MOE).2, 20 These approaches have been evaluated and the
TEF was adjudged not scientifically valid because of lack of data on the oral carcinogenicity
studies on the individual PAHs, their mode of actions and evidence of poor productivity of
the carcinogenic potency of PAH mixture based on the current proposed TEF values.2, 5, 15 In
2008, the CONTAM Panel of EFSA concluded that the use of BaP as indicator of
occurrence and effects of PAHs in food is not suitable and suggested that the eight higher
molecular weight PAHs (PAH 8): Benz[a] anthracene, Chrysene, Benzo[a] Pyrene, Benzo [b]
fluoranthene, Benzo [k] fluoranthene, Dibenz [a,h] anthracene, Benzo [g,h,i] perylene and
indeno [1,2,3-c,d] pyrene and a sub groups of four PAHs (PAH 4: Benz[a] anthracene,
Benzo[a] Pyrene, Benzo[b] fluoranthene, and Chrysene) are the most suitable indicators of
occurrence and effects of PAHs in food. It was also suggested that the margin of exposure
(MOE) approach should be used for assessment of risk exposure.2
Table 1: Polycyclic aromatic hydrocarbons considered in the present study.
Compound Abbr. Mw CAS Structure
Acenaphthene Ace 154.2 83-32-9
Acenaphthylene Acy 152.2 208-96-8
Anthracene Ant 178.2 120-12-7
4
Benz [a] anthracene BaA 228.3 56-55-3
Benzo[a] Pyrene BaP 252.3 50-32-8
Benzo[b] fluoranthene Bbf 252.3 205-99-2
Benzo[g,h,i] Perylene Bghip 276.3 191-24-2
Benzo[k]
Fluoranthene
Bkf 252.3 207-08-9
Chrysene Chy 228.8 218-10-9
Dibenz [a,h]
anthracene
DahA 278.3 53-70-3
Flouranthene Flt 202.3 206-44-0
Fluorene Flu 166.2 86-73-7
5
Indeno[1,2,3-
c,d]Pyrene
Indp 276.3 193-39-5
Naphthalene Nap 128.2 91-20-3
Phenanthrene Phe 178.2 85-01-8
Pyrene Pyr 202.3 129-00-0
Abbr: Abbreviation, Mw: Molecular weight, CAS: Chemical Abstract society service number
1.2 GENERAL OBJECTIVE
This study aims at determining the levels of PAHs in some brands of locally produced and
imported pastas in Nigerian market and also estimate the possible potential health risk
involved in their consumption by both adults and children.
1.3 SPECIFIC OBJECTIVES
1. Determine the level of some polycyclic aromatic hydrocarbons in different brands
of locally produced and imported pasta
2. To assess the level of compliance to guideline values of this PAHs from
international organization.
3. To correlate the levels of PAHs in the different brands
4. Compare the concentration of polycyclic aromatic hydrocarbons in both Nigerian
and imported brands of pastas
6
5. Estimate any possible potential health risk involved in the consumption of these
pasta
1.4 STATEMENT OF THE PROBLEM
In Nigeria and many other countries, pastas are relatively cheap, affordable by all income
classes and contribute a significant proportion to the daily food intake of children and even
adults as well. The main source of exposure to PAHs for non-smokers and nonoccupationally-
exposed adults is food. The quantity coming from the diet depends largely in
the way of cooking and the potential food contamination, which originates from packaging
materials and manufacturing.8, 21
A number of PAHs have been found to have carcinogenic and mutagenic effects while some
of them may act as synergists.22 These compounds can reach the food chain by different
ways as PAHs have been found in different food products, such as dairy products,
vegetables, fruits, oils, coffee, tea, cereals and smoked meat, therefore the analysis of PAHS
in food is a matter of concern.16
Monitoring the concentrations of PAHs in food is critical because these contaminants have
adverse effects on human
Considering that diet is a primary source of human to PAH and given the high rate of cancers
and other related diseases in the society, it is therefore necessary to determine the levels of
PAHs in human foods, estimate the dietary intakes and possible potential health risk
associated with its consumption.
7
1.5 SIGNIFICANCE OF THE STUDY
A survey of the literature indicates that there is a dearth of information on PAHs in pastas
hence, this finding will:
a. provide baseline data on PAHs for future work
b. Provide information on the risk associated with the consumption of pastas.
c. Provide data for framing guidelines and standards for PAHs in foods in Nigeria
1.6 SCOPE OF THE STUDY
The study is designed to determine the levels of 16 PAHs designated as priority pollutants by
United State Environmental Protection Agency (USEPA) in some brands of locally
manufactured and imported pastas using Gas chromatography- mass spectrometry. The
possible potential health risk will also be assessed. This work will be limited to pastas sold in
Nigeria markets.
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