Level of Total Petroleum Hydrocarbon in Fish Samples Smoked with Different Combustible Materials

The determination of total petroleum hydrocarbon (TPH) in smoked fish samples were studied using six combustible materials, such as tyres, lubricating oil, polyvinyl chloride (PVC), plastics, iroko ( chlorophoraexcelsa ) wood and black velvet ( dialiumguineense ) wood.  The result of the analysis indicates high TPH of mean value 0.8172g for fish sample smoked with tyre. The low TPH of mean value 0.0679g was obtained from fish sample smoked with iroko wood. This study established the formation of TPH during incomplete combustion of combustible materials used during smoking of fish samples. The associated health hazard of smoked fish were examined. Keywords : Fish samples, Total petroleum hydrocarbon, Combustible materials, Toxicity. DOI : 10.7176/JEES/9-2-06

associated health hazard were examined.

MATERIALS AND METHOD 2.1 Collection of Fish Samples
Fish samples catfish (Pure Dutch Clarias)were collected from a fish pond at Naze in Owerri, Imo State, Nigeria. The fish species were identified at Fishery and Aquaculture Department, Federal University of Technology, Owerri. Fish pond was chosen in this study to make sure that the fish was not contaminated from any other environment.

Preparation of Smoked Fish
1kg of fish samples were cleaned, weighed and stored in a refrigerator until use. The fish samples were place on a wire gauze and smoked for 6 hrs using smoking materials such as iroko (chlorophoraexcelsa) wood, black velvet (dialiumguineense) wood, plastics, polyvinyl chloride (PVC) pipes, lubricating oil and tyres, respectively. After smoking the fish samples were kept in an open tray for air drying. The fish samples were re-weighed after air drying to determine the moisture content. After moisture content determination the fish samples were ground and stored in a clean plastic container until use.

Extraction of Fish Samples.
10g of ground fish sample was added into an amber glass bottle. Anhydrous Na2SO4 was added into amber bottle containing fish sample and stirred using glass rod. 30ml of n-hexane was added into the bottle containing fish sample and the bottle was corked very tightly and transferred to a mechanical shaker (LAWI 2011). Then the mechanical shaker was agitated for 6 hrs.
After agitation, the sample was allowed to settle for 1 hr and then filtered through 110mm filter paper into an already weighed clean beaker. The extract was allowed to evaporate at room temperature in a fume cupboard. After evaporation the beaker was re-weighed. The difference in weight is the weightof total petroleum hydrocarbon(TPH) extracted from the fish sample.

RESULTS AND DISCUSSION
The result presented in fig 1. showeddifferent moisture content of combustible materials used for smoking of fish samples. The percentage of moisture content of combustible materials lubricating oil, tyres, plastics, PVC pipes, iroko wood and black velvet wood were 63.4%, 62.0%, 62.8%, 61.6%, 59.0%, and 60.0%, respectively. The lubricating oil has the highest moisture content of 63.4% of all the combustible materials studied, while iroko wood has the lowest moisture content of 59.0%. The order of moisture content were as follows: Lubricating oil>Plastics>Tyres>PVC pipes> Black velvet wood>Iroko wood. The result of this study indicated that the wood smoking materials have less moisture content, when compared to other combustible materials.  Fig.2 showed the level of TPH accumulation in fish samples using different combustible materials for smoking. The mean TPH accumulation in fish samples using different combustible materials such as lubricating oil, tyres, plastics, PVC pipes, iroko (chlorophoraexcelsa) wood and black velvet (dialiumguineense) wood were 0.5055g,0.8172g, 0.4769g, 0.6459g, 0.0679g and 0.0901g, respectively. This study indicated high accumulation of TPH in fish samples smoked with tyre as combustible materialwith mean TPH value 0.8172g. This study also indicated low mean TPH value of 0.0679g in fish sample smoked with iroko (chlorophoraexcelsa) wood as combustible material. The order of accumulation of TPH in fish samples using different combustible materials were as follows: Tyres> PVC pipes>Lubricating oil>Plastics> Black velvet wood>Iroko wood. This study generally indicated that all combustible materials studied accumulate high TPH in fish samples when compared to TPH accumulation in fish samples smoked with wood samples as shown in fig 2. The high TPH value obtained from fish samples smoked with tyres might be attributed to the chemical composition of tyres. Tyres are polymeric with long chain. The breaking down of this long chain synthetic polymer by combustion, generate a lot of soot during smoking that might have penetrated into fish samples. The result of this study indicated low level of TPH in fish samples smoked with wood samples as show in fig.2. The low level of TPH Legend: 1 = Lubricating oil 2 = Tyres 3 = Plastics 4 = PVC 5 = Iroko wood 6 = Black velvet wood in fish samples smoked with iroko (chlorophoraexcelsa) wood and black velvet (dialiumguineense) wood might be attributed to less complex composition of wood samples when compared to other combustible materials used in this study. Fish contaminated with TPH may be transferred to human being through food chain. It has been reported that TPH accumulation in the body causes leukemia,lymph cancer, blood cell cancer, tumors of breast (ATSDR 1999). Also one compound of TPH can cause headaches and dizziness at high concentrations and another compound can cause a nerve disorder called "peripheral neuropathy" this consist of numbness in the feet and legs. It has been reported that polyaromatic hydrocarbons (PAHs) were formed in large quantities as a result of secondary thermochemical reactions at high temperature over 700 o C (Ledesma et al. 2002). Reports have also shown that PAH compounds were formed during gasification and combustion (Mastral and Callean 2000;Richter and Howard 2000). It has been reported that polycyclic aromatic hydrocarbons were formed when incomplete combustion occurs (Lijinsky 1991). Reports have shown that PAHs were found in smoked foods, cooking oil fumes and tobacco smoke (Gomaaet al. 1993).

CONCLUSION
The result of this study indicated high level of TPH in fish samples smoked with tyres. The result of the analysis showed that all the combustible materials used in this study showed high level of TPH in fish samples except wood materials. Since the fish samples for this study were obtained from uncontaminated fish pond, it therefore showed that the TPH found in smoked fish samples were as a result of combustible materials used in smoking of fish. TPH compounds such as benzene, benzo (a) pyrene and gasoline are carcinogenic to humans (ATSDR 1999). Therefore unsmoked fish consumption is advisable to smoked fish, since smoked fish is prone to TPH contamination.