ABSTRACT
This study observed the concentration of selected heavy metals on nine (9) goat meat samples processed with three different methods (firewood singed, scrap tyres singed, and hotwater frayed) in a local slaughter unit using Atomic Absorption Spectrophotometer. The results revealed trace concentrations of the heavy metals in mostly unsinged samples prior to the singeing process, giving a control mean concentrations of 0.063±0.055 mg/kg, 0.001±0.001 mg/kg, 2.547±0.461 mg/kg, 1.95±0.125 mg/kg and 6.34±0.753 mg/kg for Cd, Pb, Cu, Zn and Fe respectively. This suggests an exposure of the slaughtered ruminants to contamination factors in the environment thereby reflecting undue levels of heavy metal concentration in the sample. Whereas increased concentrations of Cu, Zn, and Fe were observed in the firewood singed unwashed sample, Cd was below detectable range. Elevated values in concentrations of Cd, Pb, Cu, Zn and Fe was observed for the scrap tyre singed unwashed sample and conversely, a significant reduction was observed for Pb (0.009±0.01 mg/kg), Cu (6.067±0.146 mg/kg), Zn (22.41±3.304 mg/kg) and Fe (16.62±0.795 mg/kg) while Cd was below significant detectable range after the scrap tyre singed sample was washed. Furthermore, the results of Cd, Pb, Cu, Zn and Fe concentrations in frayed and unwashed as well as frayed and washed samples showed a significant reduction compared to the control and other treatments as all samples treated in this category was below significant detectable range. The environmental assessment and health status conducted using questionnaire revealed that eye irritation and skin burn were among the common health challenges faced by workers in the area while, frequent medication accounted for major economic losses. Waste management was identified as a critical issue and poses a high risk of meat contamination due to unhealthy practices. The study recommended stakeholder involvement, the general public and the meat processors in ensuring proper food handling especially at the processing unit.
TABLE OF CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table of Contents vi
List of Tables ix
List of Figures xi
List of Abbreviation and
Acronyms xii
Abstract xiii
CHAPTER
1: INTRODUCTION 1
1.1 Background
to the Study 1
1.2 Statement
of the Problem 3
1.3 Aims and Objectives of the Study 6
1.4 Significance of the Study 6
1.5 Scope of the Study 7
1.6 Justification of the Study 8
CHAPTER 2: REVIEW OF RELATED LITERATURE 9
2.1 Healthy Environment 9
2.1.1 General
principles of meat hygiene 12
2.1.2 Trace
elements and metal impurities in meat 14
2.1.3 Heavy
metals in slaughtered ruminants 14
2.1.4 Risk
of metal contamination and human safety 15
2.1.5 Effects
of heavy metals on humans 15
2.2 Singeing of Slaughtered Ruminants 18
2.3. Fuel
Sources for Singeing Meat 19
2.3.1 Wood
fuel and emissions 19
2.3.2 Tyres 20
2.3.2.1
Composition of rubber tyre 21
2.3.2.2 Utilization of tyres in singeing meat 22
2.3.2.3 Hazardous effects of open burning of tyre 24
2.3.2.4 Scrap tyre
management 26
2.4 Metals 30
2.4.1 Effects
of abattoir waste on the environment 31
CHAPTER
3: MATERIALS AND METHODS 33
3.1 Description of the Study Area 33
3.2 Research
Design 34
3.3 Sample
Collection 36
3.3.1 Meat
sample collection 36
3.4 Laboratory
Analytical Procedure 36
3.4.1 Determination
of concentration of metals in meat samples 37
3.4.2 Determination of concentration of heavy
metals in water samples 38
3.5 Questionnaire
Survey 38
3.6 Statistical
Analysis 40
CHAPTER 4: RESULTS AND DISCUSSION 41
4.1
Determined Concentrations of Selected
Heavy Metals
(Cd, Pb, Cu, Zn
and Fe) in Goat Meat Sample Singed with Firewood 41
4.2
Determined Concentrations of Selected
Heavy Metals
(Cd, Pb, Cu, Zn,
and Fe) in Goat Meat Samples Singed with Scrap
Automobile Tyres 43
4.3
Comparative Analysis of the Studied
Meat Samples by Observed
Material Treatments 47
4.4 Determined Demographic, Socioeconomic and
Health Status of the
Workers
in the Study Area 56
4.4.1 Demographic,
socioeconomic and educational assessment of the workers 56
4.4.2
Assessment of respondents by meat
processing activities 59
4.4.3
Assessment of respondents by preferred
meat processing materials 61
4.4.4 Assessment
of respondents by knowledge and awareness of
health
implication of preferred meat processing materials 63
4.4.5
Assessment of respondents by
occupational hazards, risk and exposures 65
4.4.6
Assessment of respondents by
environmental health awareness and
health status of workers in the study area 68
4.4.7 Assessment
of respondents by common health related challenges
experienced and
management methods 70
4.5
Assessed Environmental Management System
and Existing Waste
Management
Practices Adopted by the Workers in the Study Area 76
4.5.1 Occupational
health risk of goat processing emissions and common
health challenges 76
4.5.2 Health hazard and risk assessment based of
preferred material used
in singeing 79
4.5.3 Assessed environmental and waste management
system practiced
in the study area 81
4.6 Discussion 85
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS 94
5.1 Conclusion 94
5.2 Recommendations
97
References 99
Appendices 108
LIST
OF TABLES
2.1 Metal
composition of tyres 22
3.1 Tabular presentation of study design 35
3.2 Tabular presentation of sample collection
36
4.1 Mean ± SD of the heavy metal
concentration in meat singed with
firewood 42
4.2 Result of relationship between metal
concentrations in meat sample
singed with firewood 43
4.3 Mean ± SD of the heavy metal
concentration in meat quality singed
with scrap automobile tyre 43
4.4 Result of relationship between metal
concentrations in meat sample
singed with scrap automobile tyre 45
4.5 Mean
± SD of the heavy metal concentration of meat quality
frayed with hot water 46
4.6 Result
of relationship between metal concentrations in meat sample
frayed with hot water 46
4.7 Mean ± SD of the heavy metal
concentration in goat meat samples 51
4.8 ANOVA Table 54
4.9 Demographics
distribution of respondents in the study area 58
4.10 Distribution
of respondents according to meat processing activities 60
4.11 Distribution
of respondents by preferred meat processing materials 62
4.12 Distribution
of respondents by health implication awareness 64
4.13 Distribution
of respondents by perceived occupational hazards risk
factors
and exposure 67
4.14 Distribution
of Respondents by Environmental Health Status
of
Workers in the Study Area 69
4.15 Distribution
of respondents by common health challenges experienced 71
4.16 Distribution
of respondents by common health challenges experienced
and
financial losses incurred 74
4.17 Result of cross tabulation of Specialized
area of goat meat processing
against common health challenges experienced 77
4.18 Result of cross tabulation of preferred
singeing material against
common health challenges experienced 79
LIST OF
FIGURES
3.1 Map of Abia State showing the study Areas
34
4.1 Graph of heavy metal concentration on
treated goat meat 49
4. 2 Distribution of solid waste disposal and
management in the study area 81
4.3 Distribution
of water management by workers in the study area 82
4.4 Distribution
of waste water disposal in the study area 82
4.5 Distribution
of accessible toilet facility in the study area 83
4.6 Rating of waste
management practices in the study area 84
LIST OF ABBREVIATION AND ACRONYMS
BSDR: Below
Significant Detectable Range
Cd: Cadmium
Cu: Copper
Fe: Iron
FWCS:
Firewood Control Sample
FWSUS: Firewood
Singed Unwashed Sample
FWSWS: Firewood
Singed and Washed
HWFC: Hot
water Frayed Control
HWFUS: Hotwater
Frayed Unwashed
HWFWS: Hotwater
frayed and washed.
ND: Not
Detected
Pb: Lead
PML: Permissible
Limits
SATCS: Scrap
Automobile Tyre Control Sample
SATSUS: Scrap Automobile Tyre Singed Unwashed
SATSWS: Scrap Automobile Tyre Singed and Washed
Zn: Zinc
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND TO THE STUDY
Meat
ranks among one of the most significant, nutritious and energy-rich natural
food products, utilized by the humans to fulfill their regular body
requirements. It is considered quite important in maintaining a healthy and
balanced diet, which is essential in accomplishing optimum human growth and
development (Ahmad et al.,
2018). According to European
legislation, meat is defined as the edible portions, obtained from domestic
animals including caprine, bovine, ovine and porcine, including the poultry
meat, farmed and wild animals. It is a rich source of high value proteins,
variety of fats including omega-3 polyunsaturated fatty acids, zinc, iron,
selenium, potassium, magnesium, sodium, vitamin A, B-complex vitamins and folic
acid. Its composition varies with reference to its breed, type of feed being
ingested, climatic conditions and also on the meat cut, which imparts a considerable
difference on its nutritional and sensorial properties (Pereira & Vicente,
2013).
Slaughtered ruminants such as goats, sheep
and cattle for meat are normally singed to get rid of the fur. Generally, the singeing of the hide is
done under uncontrolled fires (i.e., open fires, not regulated) without
local legislative measures typically for poor households in developing
countries like Nigeria and most African countries. Hence, open fire is the major process by which hair on the skin of slaughtered
ruminant is removed. Obiri-Danso, et al. (2008). Singeing, as observed by FAO, (1985) remains the only process which
maintains the carcass hide for consumption and also evokes
flavours in the meat which are acceptable to the consumer. Before now, singeing was done
mainly by the use of firewood as fuel,
but the relative scarcity of firewood in recent times has led local butchers to
engage in the practice of using scrap car tyres as alternative source of fuel
to singe slaughtered livestock. This practice, though
unconventional and potentially dangerous, is increasingly favoured by local
butchers; as findings from a study conducted by Obiri-Danso et al.,(2008) in “Ghana reveals slaughterers opinion that
fire from the scrap” tyres is able to selectively burn off the animal fur
without cracking the hide. While in Nigeria, scrap tyres are most prevalent
materials commonly used in singeing meat instead of firewood because of its
availability and cost effectiveness to the local slaughters.
Notwithstanding, tyres are believed to contain
toxic materials which could contaminate the environment. Friday and Nwite (2016) in their
study reported the findings by the US Agency for Toxic Substances
and Disease Registry which revealed that “tyre derived fuel” (TDF) contained
several heavy metals such as lead (Pd), zinc (Zn), and copper (Cu) that could
be carcinogenic when exposed to consumers over a long period. Obiri- Danso et al. (2008) also revealed high level
of heavy metals residues in goat and cattle hides roasted with scrap tyres,
which made them unsafe for consumption. A study by Adachi and
Tainosho (2004) indicated the presence of heavy metals in tyre wears debris to
include Manganese, Iron, Nickel, Copper, Cadmium, Cobalt and Lead. The risk of
heavy metal contamination in meat therefore is of great concern for both food
safety and human health because of the toxic nature of these metals at
relatively minute concentrations (Santhi et al., 2008). In this case,
continuous consumption of such potentially contaminated meat product poses a
great source of health risk (Costa, 2000). Food safety issues have become a major issue
to consumers and health based organization, with many meat scandals hitting
European countries, most especially China and Africa. (FAO∕WHO, 2000).
There is also the possibility of a
catastrophic fire occurring because of the large quantities of petroleum and
other chemicals in tires. A burning tire creates thick, black, toxic smoke as
well as large discharges of environmental pollutants (Essumang et al., 2007).
Polychlorinated
biphenyls (PCBs) are also released when plastics are burnt, contaminating not
only the processed ruminant but also the environment. The processors are also
at risk because of the associated health hazards through inhalation of these
toxic compounds (Okiei et al, 2009). The environmental
pollution caused by the burning of tyres is a matter of great concern
worldwide, and consequently contamination of the food chain is getting
increasingly important in view of its role in human health and nutrition.
The use of scrap tyre in singeing of meat
is life threatening since it can introduce different contaminants into the meat
and when consumed, poses health risk to man. Lodu goat market slaughter unit is of no exception when it comes to using
scrap tyres as source of fuel in singeing meat. It is against this
background that the present study investigated the local livestock singeing
practices in the study area, comparing the quality of meat singed with
automobile tyre and firewood as source of fuel.
1.2 STATEMENT OF THE PROBLEM
The global awareness for a cleaner and
safer earth environment is taking an admirable pace as various stakeholder
across occupations and disciplines partner with relevant organisations to
achieve this goals, however, to some local abattoir especially in Africa the
communication is unapologetically different in view of the prevalent unsafe
meat handling techniques such as the practice of using scrap tyres for singing
livestock which appears to be conventional among local union of abattoirs.
While meat
consumption has been relatively static in the developed world, annual per
capita consumption of meat has doubled since 1960 in developing countries. Meat
consumption in developing countries has been on continuous increase from a
modest average annual per capita consumption of 10 kg in the 1960s to 26 kg in
2000 and has been estimated to be at 37 kg around the year 2030 according to
FAO projections (FAO, 2007). Growing
population and incomes, along with changing food preferences are increasing the
demand for livestock products (FAO, 2012). It is pertinent to note that
tyre-singeing leads to the accumulation of toxic substances such as heavy
metals in meat which poses health risks when consumed. Due to their non-biodegradable and persistent
nature, heavy metals are accumulated in vital organs in the human body such as
the kidneys, bones and liver and are associated with numerous serious health
disorders (Duruibe et al., 2007). Individual metals exhibit specific
signs of their toxicity. Persistent over-indulgence in taking magnesium
supplements can lead to muscle weakness, lethargy and confusion (Lenntech,
2012). The unremitting consumption or exposure to high level of various heavy
metals results to detrimental effect on different organs in the human
body. For example, Lead, Zinc, Copper
and Aluminium poisoning have been implicated with gastrointestinal (GI)
disorders, diarrhoea, stomatitis, tremor, hemoglobinuria causing a rust-red
colour to urine, ataxia, paralysis, vomiting and convulsion, depression, and
pneumonia (McCluggage, 1991). An uptake of too large quantities of nickel leads
to higher chances of development of lungs, nose, larynx and prostate cancer,
lung embolism, respiratory failure, birth defects, asthma, chronic bronchitis
and heart disorders (Lenntech, 2012). Copper (Cu) is known to cause damage to
the liver; lead (Pb) may cause cognitive development problems, increase in
blood pressure and cardiovascular diseases (Nolan, 2003). Manganese poisoning
can also cause Parkinson’s disease, lung embolism and bronchitis (Santamaria,
2008). zinc (Zn) reduces immune function
and the levels of high density lipoproteins; cadmium causes kidney dysfunction
and reproductive deficiencies (FAO, 2001. Ikem & Egiebor, 2005) Hauser and
Hauser, (2009), reported that high doses of cadmium can lead to kidney
failure, damage to testicles and liver. Adverse Manganese effects occur in the
respiratory tract and in the brain as well. Some symptoms of manganese
poisoning are hallucinations, forgetfulness and nerve damage. European Union
(2002) unmasked that the nature of the effects of these metals can be toxic
(acute, chronic or sub-chronic), neurotoxic, carcinogenic, mutagenic or
teratogenic.
In addition, large
amounts of greenhouse
gases such as Dioxin can become absorbed in vegetation consumed by livestock.
Dioxin does not breakdown; it accumulates in the fatty tissues of animals and
humans that consume the contaminated vegetation, meats, chickens and dairy
products. In humans, these Dioxins can lead to productive impairments,
development of injuries and an increase in the risk of diabetes.
Furthermore, tyre as non-biodegradable combustible
material, when subjected to uncontrolled open fire conditions at low
temperature produces black plumes of smoke as well as toxic volatilization
products such as soot, which become incorporated into the ambient environment
causing air and water pollution (Mohammad et al., 2012) as well as result
in human and environmental hazard. Open burning of these
scrap tyres used in singeing meat releases volatile organic compounds (VOCs)
and polycyclic aromatic hydrocarbons (PAHs) into the environment and this
causes air, and water pollution thereby posing serious health risk to
individuals living around the vicinity, most especially the meat processors.
Firewood and scrap automobile tyres as
fuel sources from the present study therefore determined and compared the
implication of using two common livestock singeing materials on the meat quality,
environment and the occupational health of the workers.
1.3 AIMS AND OBJECTIVES OF THE STUDY
The
study aims at determining in a comparative assessment, the heavy metal
concentrations in locally processed meat singed using vehicle scrap tyres and
firewood. The aim would be achieved through the accomplishment of the following
objectives.
i.
Determination of the concentrations of
selected heavy metals (Cd, Pb, Cu, Zn,
and Fe) in goat meat samples singed with firewood in
the study area.
ii.
Determination of the concentrations of
selected heavy metals (Cd, Pb, Cu, Zn,
and Fe) in goat meat
samples singed with scrap automobile tyres in the study
area.
iii.
Determination of the demographic, socioeconomic
and health status of the
workers in the study
area.
iv.
Assessment of existing environmental
and health management system as well as
waste management
practices adopted by the workers in the study area.
1.4 SIGNIFICANCE OF THE STUDY
Many studies have recognized the increased demand for protein rich food
from both plants and animal sources have increased to address global
malnutrition issues. Available statistics by FAO (2019)
estimated that between 2012 and 2050, the aggregate consumption of all
livestock products in Nigeria will more than triple, projected increase varies
from 216 percent for mutton and goat meat to 266 percent for poultry meat. This
means that on an annual basis, demand will grow between 3.3 and 3.8 percent,
which translate in major increases in volume terms. In specific terms, the
report estimated the consumption of mutton and goat meat at 467,000 tonnes with
a projected 3.8% annual increase rate giving rise to 878,000 tonnes in 2030 and
1,473,000 tonnes in the year 2050, concomitantly resulting to increase and wide
spread of metal contaminated food in the society due to unsafe processing.
However, food contamination at every stage of the food production chain
is unacceptable since it threatens the health of consumers of such foods. Food
safety issues poses as a major concern to consumers and health-based organizations,
with many meat scandals hitting European countries and China. Research has
shown that Scrap tyres contain different compounds with heavy metals and other
toxic substances. Grosse-Daldrup & Scheubel (1996) recommended used tyres which are synthetic products as an
alternative solid fuel for the cement industry in the developed countries. This
however did not include food processing plants. Mokrzycki, et al., (2003)
cautioned that before using any material as an alternative fuel (e.g. scrap
tyre) the toxicity (organic compounds, heavy metals), composition, content of
ash, content volatiles, calorific value of the material should be evaluated
first.
Sunu, (2013) and USFA, (1999) cited
the Technical Guidelines on the Identification and Management of Used Tyres as
postulated by the Basel Convention 1999 that used tyres contain a total of
approximately 1.5% by weight of hazardous waste compounds, these compounds are
encased in the rubber compound or present as an alloying element.
1.5 SCOPE OF THE STUDY
The
study focused mainly on comparative assessment of heavy metal concentrations in
goat meat samples singed with scrap automobile tyres and firewood in the
slaughter unit located at Lodu goat market in Umuahia, Abia State, as well as
hot water frayed sample in the laboratory. The study also surveyed the
slaughtering practices, as well as the demographic, socioeconomic and
occupational health and waste management practices adopted by the meat
processors (Butchers) using a structured questionnaire according to recommended
standards.
1.6 JUSTIFICATION OF THE STUDY
This present study
will do justice in unmasking the toxic metal components of meat singed with
scarp tyres, comparing the findings with the conventional method of using
firewood as fuel, as well as hot water method and relevant standards. The
findings will be useful to relevant stakeholders including legislative bodies,
health organisations and Environmental agencies to enable the ease of curbing
this unsafe and unhealthy practice of singeing meat with scrap automobile tyre.
Login To Comment