LEVELS OF POLYCYCLIC AROMATIC HYDROCARBONS IN FRESH WATER FISH DRIED UNDER DIFFERENT DRYING REGIME

ABSTRACT 

Preservation of fish by drying over different types of heat regimes have been known. However, there has not been a comprehensive comparison in terms of the possible contamination associated with these drying regimes. This work was set to evaluate the levels of PAHs that are likely to accumulate in the bodies of fresh water fishes dried under heat from charcoal, sun (sun drying), electric oven and polythene augmented drying regimes (burning of used cellophone materials). The levels of sixteen PAHs were determined in fish samples harvested from Otuocha River in Anambra State, Nigeria. The fish samples were dried, pulverized and subjected to soxhlet extraction using n-hexane at 600c for 8hrs. The water content of the eluants were further removed with florisil clean-up before Gas chromatographic – mass spectrometric analysis. Results obtained showed that sun-dried fish had PAHs concentration to be 35.7+

0.2µg/g; oven dried gave 47.7+ 0.2µg/g and charcoal dried 79.53+ 0.2µg/g, while drying with firewood resulted in 188.1+ 0.2µg/g. Charcoal drying augmented with polythene resulted into PAHs level of 166.2+ 0.1µg/g while fish dried under heat generated from burning firewood and polythene material resulted into PAHs concentration of 696.3+0.2µg/g. Preliminary analysis of the fresh water samples and the undried fish samples (control) revealed that the fresh water contained total PAHs level of 2.86+ 0.1µg/ml, while the fresh fish 4.97+ 0.2µg/g. The concentration of PAHs in all the dried fish under different drying agents were significantly higher than the control. The result is more worrisome in that even the fishes dried under the sun have PAHs significantly higher than that of the control (p<0.05). It is apparent that the increase in PAHs must have come from the environmental PAHs (exposure) under which the fishes were dried (under sun). For the other drying regimes, in which the levels of PAHs were significantly higher than that of sun-dried, it can be concluded that the excessive PAHs in the body of the dried fish were from the “burning” or drying agents. More significantly are the observed very high increase in PAHs when drying was augmented with polythene, an agent known to be a high source of PAHs when incinerated. Consumers of dried fish should therefore beware of the dried fish they purchase from the local market. 

TABLE OF CONTENTS

CHAPTER ONE: INTRODUCTION

1.1. Introduction - - - - - -

1.2. Physical and Chemical Characteristics of PAHs -

1.3. Sources and Emission of PAHs - -

1.3.1. Stationary Sources  - - - -

1.3.1.1. Domestic Sources - -

1.3.1.2. Industrial Sources - -

1.3.2. Mobile Sources - -

1.3.3. Agricultural Sources -

1.3.4. Natural Sources - -

1.3.5 Uses of PAHs- - - -

1.4. Routes of Exposure for PAHs -

1.4.1 Air - - - -

1.4.2 Water -

 1.4.3 Soil - - - -

1.4.4. Foodstuffs -

1.4.5. Other Sources of Exposure - -

1.5. Individuals at Risk of Exposure - - -

1.6. Standards and Regulation for PAH Exposure -

1.7. Metabolism of PAHs - - -

1.7.1. Fate of PAHs in Soil and Groundwater Environment -

1.7.2. Fate of PAHs in Air and their Ecotoxicological consequences

1.8 Human Health Effects - - - - -

1.8.1 Acute or Short-Term Health Effects - - - -

1.8.2. Chronic or Long-Term Health Effects - - -

1.8.3 Carcinogenicity - - - - -

1.8.4. Teratogenicity - - - - -

1.8.5. Genotoxicity - - - - - -

1.8.6. Immunotoxicity - - - - -

1.8.7. effect of PAHs Pathogenic Change - - -

1.9. Fish - - - - - -

1.9.1. Food Smoking - - - -

1.10. Rationale of Study - - - -

1.11. Aims and Objectives - - - -

CHAPTER TWO: MATERIALS AND METHODS

2.0 Material and methods - - - - -

2.1. Materials - - - - - -

2.1.1. Apparatus and Equipment - - - -

 2.1.2. Chemicals - - - -

2.1.3. Fish Samples - - - -

2.1.4. Study Site - - - -

2.2. Methods - - - -

2.2.1. Collection of Fish Samples and Drying

2.2.2. Sample Preparation for the Analysis of Dried Fishes -

2.2.3. Preparation of Florisil for clean-up - - -

2.2.4. Instrument Analysis - - - - -

CHAPTER THREE: RESULTS

Result - - - - - - -

CHAPTER FOUR

4.0. Discussion - - - - - -

Conclusion - - - - - -

Reference

Appendices

LIST OF TABLES

Table 1: Physical and Chemical Properties of PAHs - -

Table 2: levels of PAHs Exposures from Workplace - - -

Table3: Carcinogenic Classification of Selected PAHs -

Table4: Temperature Condition of GC-MS - -

Table 5: Weight of Fish used in October, November and January 2014

Table 6: GC-MS result of fish samples in October 2013 - -

 Table 7: GC-MS result of fish samples in November 2013

Table 8: GC-MS result of fish samples in January 201 -

Table 9: Statistical mean value of GC-Ms result of the three months - -

LIST OF FIGURES

Figure 1: Mechanism of Activation of BaP by Cytochrome P450 and

Epoxide Hydroxilase  - - -

Figure 2: Aryl hydrocarbon receptor (AhR) pathway activated by BaP -

Figure 3: Bay region of some PAHs - -

Figure 4: Map Showing Otuocha River in Anambra State

Figure 5: Monthly distribution of Acenaphthylene in various treatments -

Figure 6: Monthly distribution of Anthracene in various treatments - -

Figure 7: Monthly distribution of 1,2 Benzanthracene in various treatments -

Figure 8: Monthly distribution of Benzo(pyrene) in various treatments

Figure 9: Monthly distribution of Benzo(fluoranthene) in various treatments

Figure 10: Monthly distribution of Benzo(g,h,i)perylene in various treatments

Figure 11: Monthly distribution of Benzo(k)fluoranthene in various treatments

Figure 12: Monthly distribution of chrysene in various treatments - -

Figure 13: Monthly distribution of Dibenz(a,h)anthracene in various treatments

Figure 14: Monthly distribution of fluoranthene in various treatments -

Figure 15: Monthly distribution of fluorene in various treatments

Figure 16: Monthly distribution of indeno(1,2,3-cd)pyrene in various treatments

Figure 17: Monthly distribution of Naphthalene in various treatments -

Figure18: Monthly distribution of Pyrene in various treatments -

 LIST OF ABBREVIATIONS

PAHs – Polycyclic Aromatic Hydrocarbons

LMW – Low Molecular Weight

HMW – High Molecular Weight

ATSDR – Agency for Toxic Substances and Disease Registry

EPA – Environmental Protection Agency

POP - Persistent Organic Pollutants

WHO - World Health Organization

MCL - Maximum Contaminant

PPB - Parts Per Billion

IARC – International Agency for Research on Cancer

OSHA – Occupational Safety and Health Administration

Ctpv – Coal Tar Pitch Volatiles

PEL – Permissible Exposure Limit

NIOSH – National Institute for Occupational Safety and Health

TLV- Threshold Limit Value

TWA – Time Weighted Average

REL – Recommended Exposure Limit

FAO – Food and Agricultural Organization

FDA Food and Drug Administration

BAP – Benzo (a) Pyrene

CDC – Center for Disease Control and Prevention

BEI – Biological Exposure Index 

DNA – Deoxynbonucleic Acid

SPSS – Statistical Product and Solution Services

ANOVA – One Way Analysis of Variance

GC-MS – Gas Chromatography Mass Spectrometer

F/P – Ratio Flouranthene to Pyrene

KOW – Octanol-Water Partition Coefficients

KOC – Partition Coefficient for Organic Carbon

CHAPTER ONE

1.1 INTRODUCTION

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds consisting of two or more fused benzene rings (linear, cluster or angular arrangement), or compounds made up of carbon and hydrogen atoms grouped into rings containing five or six carbon atoms. They are called “PAH derivatives” when an alkyl or other radical is introduced to the ring, and heterocyclic aromatic compounds (HACs) when one carbon atom in a ring is replaced by a nitrogen, oxygen or sulphur atoms. PAHs originate mainly from anthropogenic processes particularly from incomplete combustion of organic fuels. PAHs are distributed widely in the atmosphere. Natural processes, such as volcanic eruptions and forest fires, also contribute to an ambient existence of PAHs (Suchanova et al., 2008). PAHs can be present in both particulate and gaseous phases, depending on their volatility. Low molecular weight PAHs (LMW PAHs) that have two or three aromatic rings (molecular weight from 152 to 178g/mol) are emitted in the gaseous phase, while high molecular weight PAHs (HMW PAHs), molecular weight ranging from 228 to 278g/mol, with five or more rings, are emitted in the particulate phase, (ATSDR, 1995) . In the atmosphere, PAHs can undergo photo-degradation and react with other pollutants, such as sulfur dioxide, nitrogen oxides, and ozone. Due to widespread sources and persistent characteristics, PAHs disperse through atmospheric transport and exist almost everywhere. There are hundreds of PAH compounds in the environment but in practice PAH analysis is restricted to the determination of six (6) to sixteen (16) compounds. Human beings are exposed to PAH mixtures in gaseous or particulate phases in ambient air. Long term exposure to high concentration of PAHs is associated with adverse health problems. Since some PAHs are considered carcinogens, inhalation of PAHs in particulates is a potentially serious health risk linked to lung cancer (Philips, 1999).

1.2. Physical and Chemical Characteristics of PAHs.

PAHs are a group of several hundred individual organic compounds which contain two or more aromatic rings and generally occur as complex mixtures rather than single compounds. PAHs are classified by their melting and boiling points, vapour pressure, and water solubility, depending on their structure. Pure PAHs are usually coloured, crystalline solids at ambient temperature. The physical properties of PAHs vary with their molecular weight and structure (Table1). Except for naphthalene, they have very low to low water solubilities, and low to moderately high vapour pressures. Their octanol-water partition coefficients (Kow) are relatively high, indicating a relatively high potential for adsorption to suspended particles in the air and in water, and for bioconcentration in organisms (Sloof et al., 1989). Table 1 shows physical and chemical characteristics of few selected PAHs from the sixteen (16) priority PAHs, listed by the US EPA. (see appendix). Most PAHs, especially as molecular weight increases, are soluble in non-polar organic solvents and are barely soluble in water (ATSDR, 1995).

Most PAHs are persistent organic pollutants (POPs) in the environment. Many of them are chemically inert. However, PAHs can be photochemically decomposed under strong ultraviolet light or sunlight, and thus some PAHs can be lost during atmospheric sampling. Also, PAHs can react with ozone, hydroxyl radicals, nitrogen and sulfur oxides, and nitric and sulfuric acids which affect the environmental fate or conditions of PAHs (Dennis et al., 1984; Simko, 1991).

PAHs possess very characteristic UV absorbance spectra. Each ring structure has a unique UV spectrum, thus each isomer has a different UV absorbance spectrum. This is especially useful in  the identification of PAHs. Most PAHs are also fluorescent, emitting characteristic wavelengths of light when they are excited (when the molecules absorb light). Generally, PAHs only weakly absorb light of infrared wavelengths between 7 and 14µm, the wavelength usually absorbed by chemical involved in global warning (Ramanathan, 1985).

Polycyclic aromatic hydrocarbons are present in the environment as complex mixtures that are difficult to characterize and measure. They are generally analyzed using gas chromatography coupled with mass spectrometry (GC-MS) or by using high pressure liquid chromatography (HPLC) with ultraviolet (UV) and fluorescence dectetors (Slooff et al., 1989) 

Table 1 Physical and Chemical Characteristics of Some Popular PAHs