POLYCYCLIC AROMATIC HYDROCARBON (PAH) IN COOKED (CHARRED) RICE: LEVELS, RISK ASSESSMENT AND SOURCE CHARACTERISATION. Essumang D. K.

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1 POLYCYCLIC AROMATIC HYDROCARBON (PAH) IN COOKED (CHARRED) RICE: LEVELS, RISK ASSESSMENT AND SOURCE CHARACTERISATION Abstract Essumang D. K. Department of Chemistry, University of Cape Coast, Cape Coast. Ghana *Corresponding Author s dessumang@ucc.edu.gh; kofiessumang@yahoo.com (Submitted on 16 th July, 2014 and accepted on 22th December, 2014) The presence of polycyclic aromatic hydrocarbons (PAHs) as carcinogens in food has been known since the 1950s. Hundreds of individual PAHs may be formed or released as a result of incomplete combustion or pyrolysis of organic matter (heat generated food toxicant). The amount of PAHs present in cooked foods depends on the duration of the cooking process, the temperature of the heat source, the distance of the food material from the heat source and the presence of fat or oil in the food. This research seeks to determine the levels of PAHs introduced into cooked rice ( kanzou or charred) through some common cooking methods in Ghana using the gas chromatography with flame-ionization detection (GC/FID). The result showed the presence of eighteen PAHs including some carcinogens such as benzo(a)anthracene, benzo(b)fluoranthene dibenz(a,h)anthracene and benzo(e)pyrene in almost all the samples analyzed. The levels detected were relatively higher than accepted by the European Commission but risk analysis showed low levels of risk as compared to U.S EPA accepted risk of 1.0E-06 to 1.0E-04. Source characterization of PAHs showed combustion of oil and rice at an unregulated high temperature as the main source of PAHs in the cooked rice. Key Words: Polycyclic Aromatic Hydrocarbon, kanzou, charred rice, risk assessment, source characterization Introduction The primary objective of food processing operation is to improve the quality of the foodstuff to make them palatable for human consumption. Nevertheless, some processing operations do induce the formation of materials that are potentially toxic and harmful to humans (heat generated food toxicant). Thus, toxic substances may be formed by the interaction between any endogenous and/or exogenous food components or their derivatives or between these substances and outside agents, such as oxygen. Chemical degradation may also occur due to heat, light etc., and other agents and in turn may result in the formation of toxic compounds (Deshpande, 2002). The presence of polycyclic aromatic hydrocarbons (PAHs) as carcinogens in food has been known since 1950s. These chemicals have also been found in uncooked vegetable oils, charred meat, flour, bread, and marine life in contaminated waters (Furihata and Matsushima, 1986; Simko, 2002). At least, about 18 mutagenic and/or carcinogenic PAHs have also been found in uncooked vegetables, fruits, cereals, and vegetable oils (Concon, 1988; Deshpande, 2002; Alomirah, 2010). The amount of PAH present in cooked foods depends on the duration of cooking, the distance of materials from the heat source, whether the melted fat is allowed to drop into the heat source or hot surfaces, etc. The amounts of PAHs in foods vary from 0 to 400µg/kg (Furihata and Matsushima, 1986).

2 Polycyclic aromatic hydrocarbon contamination of food can originate from different sources among which the sources of major importance are the environment and food processing operations. Processing procedures, such as smoking, drying roasting, baking, frying, barbecuing/grilling and cooking of food are a recognized major source of contamination of PAH. Data reported in the literature on PAH in smoked foods are highly variable. The main reason for such discrepancies is the differences in the procedures used for smoking. The content of 12 PAHs in smoked fishery products from modern smoking kilns with external smoke generation and procedures that remove high-boiling compounds such as PAH and particles potentially containing PAH have been compared with products from traditional smoking kilns where the smoke is generated in direct contact with the product. The average benzo (a) pyrene concentration determined for the traditional kilns was 1.2µg/kg and 0.1µg/kg for the modern kills (Codex Agenda Item 17h). Levels of individual PAHs, as high as 200µg/kg in food, have been found in smoked fish and meat. PAH formation during charcoal grilling is shown to be dependent upon the fat content of the meat, the duration of cooking and the temperature used. For example a heavily barbecued lamb sausage contained 14µg/kg of the sum of six PAH, considered by European Union Scientific Committee on Food (EUSCF, 2002) to be carcinogenic and mutagenic. When foods are subjected to high temperatures (> o C), pyrogenic compounds are produced. Heating of fats and oils to high temperatures can result in oxidation and polymerization reactions, the products may be harmful to humans. The formation of PAH is only significant at high temperatures. Temperatures between 400 and 1000 o C produces significant amount of PAHs (Toth and Pothast, 1984; Concon, 1988; Deshpande, 2002). At this temperature, a significant amount of charred or tarry products is formed. They are most typically formed from pyrolysis of fats and oils at temperatures above 400 o C. This can occur if portions of the food encounter very hot surfaces. Benzo(a)pyrene (3,4- benzpyrene) has been identified as the active component of charred material with benzo(b)fluoranthene, dibenz(a,h)anthracene, dibenz(a,i)pyrene and dibenz(a,h)pyrene occurring at various levels (Badger, 1962; Deshpande, 2002). Health effects due to PAHs and other contaminant in food has been discussed extensively in recent times (Shen, et al. 2008) which include growth retardation, low birth weight, small head circumference, low IQ, damaged DNA, in unborn children and disruption of endocrine systems, such as estrogen, thyroid and steroids. Skin changes (thickening, darkening, and pimples) and reproductive related effects such as early menopause due to destruction of ovum and cancers (breast cancer) have been identified (Davis, et al., 1987; Boström et al., 2002; ATSDR, 2007; Gray, 2008; Shen, et al. 2008) Humans are basically exposed to PAHs through a) the respiratory tract by inhalation of PAHcontaining matter such as cigarette smoke, vehicle exhaust, PAH contaminated air emitted from certain industries or by the burning of wood for heating, etc., b) the digestive tract following intake of PAH-containing foodstuffs (e.g., fried and charcoal-grilled meat) and PAH contaminated vegetables and crops grown close to areas with intense traffic, etc., and c) the skin following contact with substances such as petroleum products (e.g., soot, pitch, and tars) (Boström et al., 2002). The emphasis of the digestive tract PAH exposure to humans over the years has mostly focused on meat and smoked fish products (Furihata and Matsushima, 1986). However, the method of certain food preparations may induce PAHs into the food (pyrolysis of the food) as a result of cooking at

3 high temperatures above 400 o C (Toth and Pothast, 1984; Concon, 1988; Deshpande, 2002). An example is the cooking of rice, a staple food in Ghana. Jollof - rice one of the most popular rice foods made from rice, tomatoes, meat or fish and oil (Wilson, 1972) is usually cooked at very high (unregulated) temperature and that result in part becoming charred (at the base of the saucepan). This portion of rice is known in Ghana as kanzou or under and because it is cheap it is heavily patronized by most people. This research seeks to determine the levels of PAHs introduced into this portion of the cooked rice through some common cooking methods in Accra, Ghana and to assess possible cancer and non cancer risk. Materials and Method Sampling Ten (10) samples each were collected from popular cooked rice vendors in Accra, Cape Coast, Takoradi and Agona Swedru and composited. About 500g of rice samples were taken in aluminum foil and stored in a refrigerator. Four samples comprising uncooked, cooked rice, charred (burnt part) cooked plain and jollof rice of same brand was prepared using non-stick cooking utensil. These four samples were also collected in aluminum foil, stored in a refrigerator and used as control samples (Grimmer, et al 1975). The table in Appendix I give the samples and their codes. Procedure About 20 g of the thawed sample from the refrigerator was homogenized and weighed into a labeled round bottom flask. About 0.1mL of an internal standard (2,2-di-naphthyl and 3,6- dimethylphenonthrene mixture) was added to the weighed sample in a flask. Also, 100 ml of 2M methanolic-koh was then added and saponified for 4 hours. After saponification, the condenser was flushed with 25 ml of 2M methanolic KOH into the sample (Kazerouni 2001). The solution was cooled and transferred into a 500 ml separating funnel with the aid of a glass funnel fitted with a glasswool. 25 ml of methanol-water (4:1) was added to the residue in the flask, swirled and added to the solution in the separator. About 40 ml cyclohexane was added to the filtrate in the separator, mixed gently and layers were allowed to separate. The lower layer was collected into a second separating funnel and the extraction process repeated with another 40 ml cyclohexane. The lower KOH solution was set aside and the cyclohexane extracts were combined in the first separator. 40 ml methanol: water (1 + 1) was added to the cyclohexane extracts; gently shook to wash and the layers were allowed to separate. The lower layer was drained and discarded later. About 80 ml N, N-Dimethylformamide (DMF)-Water was added to the cyclohexane extract shook gently and layers allowed separating. The lower DMF-water layer was collected into a second separating funnel. Extraction with cyclohexane was repeated with another 40 ml DMF-water, allowed to separate, the lower DMF-water extract drained and added to previous extract 120 ml of water and 80ml cyclohexane were added to the combined DMF-water extract, shook gently and layers allowed to separate with the lower DMF-water as waste. The cyclohexane extract was released onto an anhydrous sodium sulphate (previously dried at 550 o C for an hour) in a glass funnel plugged with glass wool. An amount of dichloromethane (DCM) was used to rinse the sodium sulphate and the filtrate added to the extract in a Turbo Vap II tubes. A drop of iso-octane was added to the extract as a keeper. Nitrogen gas was used to evaporate the extract at

4 30 o C to a volume of about 0.5 ml. The bond elute column was then conditioned with 3.0 ml methanol followed by 3.0 ml DCM-Pentane solution. The extract was made to pass through the bond elute column drop wise and eluted with 0.5 ml DCM-Pentane solution. Then the column was filled with 3 ml DCM-Pentane solution. The elution was repeated with the solvent. A drop of iso-octane was added to the eluted solution and nitrogen gas was used to reduce the volume to 0.5 ml at 30 o C. The reduced solution was quantitatively transferred into a vial and stored for GC-FID analysis. Instrumental Analysis The final extracts, quality control and blanks were automatically injected on the gas chromatograph in a splittless mode. The conditions of the chromatographic system were as follows: Column: Agilent 19091S 436, HP-5MS, 60m x 250µm.x 0.25µm, Column head pressure: psi, Column flow: 1.4 ml/min, injection volume used was 1.0 µl, Make-up flow: 45.0 ml/min., H2 flow: 40.0ml/min, Air flow: 300 ml/min, Purge flow: 75.0 ml/min., Purge time: 1.0 min, Oven temperature programme: initial temperature 60 o C, hold 2 min, rate 12 o C/min to 250 o C, rate, A 3 o C/min to 310 o C, hold for 10 min, Injector temperatures 280 o C, Detector, temperature: 350 o C, Volume injected: 2 µl Gas chromatography analysis separates all of the components in a sample and provides a representative spectral output. The sample vials containing the extracts were arranged on a platform at the injection chamber and the injection of 2 µl was automatically done by the instrument. Quality Control Approximately 0.04 ml of a Certified Reference Material (CRM) 2260 (NIST) of concentration 60 µg/ml was added to 100 ml of 2M methanolic KOH solution in a round bottom flask and treated as was done for the samples. The final concentrate of 0.5 ml was expected to have a concentration of 5µg/mL of the standard added. This was done to ensure that the method was effective and reliable. Table 1: Percentage Recovery Using NIST Certified Reference Material Compound Name Average µg/ml True Value µg/ml Relative Error (%) % Recovery Naphthalene Methylnaphthalene Methylphthalene Biphenyl ,6-Dimethylnaphthalene Acenaphthylene Acenaphthene ,3,5-Trimethylnaphthalen Fluorene Phenanthrene Anthracene Methylphenanthrene IS 3,6-DMP

5 Fluoranthene Pyrene Benzo(a)anthracene Chrysene IS BB-Biphenyl Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Perylene Indeno(1,2,3cd)pyrene Dibenz(a,h)anthracene Benzo(g,h,i)perylene Results from the NIST reference material showed high recovery of PAH values that ranged from 94% to 101% with an average PAH recovery of 98%. The use of these recovery results which were from certified NIST reference material was used to assess the efficiency of extraction of PAH from the charred rice sample matrix is highly contentious since the two are of different matrices. However, the values could be used to establish the reliability of the extraction system as well as the efficiency of the GC/FID instrument since that was the only CRM available at the time of the analysis. Calculation of Carcinogenic Risk Human health evaluation computerized software-risc 4.02 (USEPA, 1989) was used in the evaluation of the cancer and non cancer risk assessment. Carcinogenic risks are estimated as the incremental probability of an individual developing cancer over a lifetime as a result of exposure to the potential carcinogen. This risk is referred to as the individual excess lifetime cancer risk (IELCR) or just carcinogenic risk. Published values of chemical carcinogenic toxicity (slope factor) are used to calculate risk from the Lifetime Average Daily Dose (LADD): IELCRij = SFij LADDij (1) Where IELCRij = individual excess lifetime cancer risk for chemical i exposure route i [dimensionless], SFij = slope factor for chemical i exposure route j [mg/kg-d]-1, LADDij = lifetime average daily dose for chemical i exposure route j [mg/kg-d]. Calculation of Hazard Index Human health evaluation computerized software-risc 4.02 (USEPA, 1989) was used in the evaluation of the cancer and non cancer risk assessment. The potential for non-carcinogenic effects was evaluated by comparing an exposure level over the exposure duration (maximum of 70 years) with a reference dose derived for a similar exposure period. This ratio of exposure to toxicity for an

6 individual pathway and chemical is called a hazard quotient. The hazard quotients are usually added across all chemicals and routes to estimate the hazard index. Some, however, will argue that it is more appropriate to only sum the hazard quotients for chemicals that affect the same target organ (e.g. liver or blood). The non-cancer hazard quotient assumes that there is a level of exposure below which it is unlikely that even sensitive populations would experience adverse health effects (USEPA, 1989). Results and Discussion The precision and suitability of the method to the measuring equipment used, was initially established using the certified reference material. This was done by using the reference material as a sample and treated the same way as the real samples. The percentage recoveries were then calculated. The method verification and sample results are tabulated below (table 1) above. PAH Concentration in Rice The rice used as a control in this research work showed various levels of PAH. Notable among them were 2-Methylnaphthalene with concentration 0.16 mg/kg, 2, 3, 5 Trimethylnaphthalene with 0.37 mg/kg, pyrene with 0.24 mg/kg, benzo (b) fluoranthene with 0.66 mg/kg and dibenz (a, h) anthracene with 2.54 mg/kg concentrations. Those that showed high values which included Benzo (b) fluoranthene concentration almost doubled from 0.66 mg/kg in C1 to 1.2 mg/kg in C2 (table 3). This may be due to the cooking temperature. Dibenz (a,h) anthracene was however not detected in C2, though it was detected in C1, this may either be due to pretreatment of rice before cooking or temperature differences during cooking. The control, C3 (table 3) was partially burnt rice which was cooked in a non-stick cooking utensil. Levels of detection followed trend as that of C2 but had elevated levels for Benzo (g.h.i) perylene with concentration of 0.58 mg/kg compared to 0.30 mg/kg in C2 (table 3). The level of PAHs in the jollof rice (C4) of the same brand of rice used as control showed a similar trend as that of C3 but recorded 0.28 mg/kg of Dibenz (a,h) anthracene which was not detected in C2 and C3. Possibly this may be due to the vegetable oil used in preparing the jollof and the temperature factor (Alomirah, 2010). Two PAH classified as a strong carcinogen, namely benzo (b) fluoranthene and dibenz (a, h) fluoranthene were detected in the uncooked control sample (C1). This confirms similar work by Liu and Korenega (2001) which demonstrate levels ranging from 0.05 to 0.08 mg/kg dry weight in unpolished and polished rice. Liu and Korenega (2001) concluded that PAHs in polished rice was far lower than the unpolished rice which was due according to them to the purification stages (Liu and Korenega 2001; Kazerouni 2001). In this study, the average distribution of PAH in the rice samples from vendors ranged from the lowest of none detected for chrysene, biphenyl, benzo(k)fluoranthene, benzo(a)pyrene, perylene, indeno (1,2,3-cd)pyrene to the highest 4.2 mg/kg of 2-methylnaphthalene. The mean results from

7 Concentration in mg/kg table 2 shows that, 2-methylnaphthalene and benzo (g,h,i) perylene are the most predominant PAHs in the charred rice (fig 1). Mean Levels of PAHs in Control (uncooked and cooked rice) and Charred rice from Vendors Control - Uncooked Control - Charred Vendors - charred Naphthalene 2-Methylnaphthalene 1-Methylnaphthalene Biphenyl 2,6-Dimethylnaphthalene Acenaphthylene Acenaphthene 2,3,5-Trimethylnaphthalene Fluorene Phenanthrene Anthracene 1-Methylphenanthrene Fluoranthene Pyrene Benzo(A)Anthracene Chrysene Benzo(B)Fluoranthene Types of PAHs Benzo(K)Fluoranthene Benzo(E)Pyrene Benzo(A)Pyrene Perylene Indeno(1,2,3-Cd)Pyrene Dibenz(A,H)Anthracene Benzo(G,H,I)Perylene Fig. 1: Mean levels of control (Uncooked and cooked) rice and samples from Vendors Despite the fact that the concentrations of PAH from the various samples are comparable, some of the PAH were more predominant with some specific rice samples though some others either decreased or increased across the vendors (table 3). The least total PAH concentration of 2.8 mg/kg (S6) which is less charred, whereas the highest total PAH concentration of 12.9 mg/kg (S10) which was totally charred from table 3. A close observation of the above results shows that the use of very high temperature resulted in high PAH levels. Compounds with PAH molecular weights ranging from (i.e. Benzo (e) pyrene, benzo (b) fluoranthene, perylene, dibenz(a,h)anthracene, 2,3,5- trimethylnaphthalene and benzo(g,h,i) perylene) apart from 2-methylnaphthalene recorded the highest levels (Badger, 1962; Deshpande, 2002; Kanchanamayoon and Tatrahun, 2009) Sample S1, a jollof rice, sourced from a sales point in Teshie contained most of the PAH under investigation. Two of the strong carcinogens, namely benzo (b) fluoranthene and dibenz (a, h) anthracene had values 0.92 mg/kg and 1.95 mg/kg respectively (table 3). The range of PAH concentration was between < mg/kg with highest dibenz (a, h) anthracene (1.95 mg/kg) followed by benzo (g, h i) pyrylene (1.88 mg/kg), benzo (b) fluoranthene (0.92) and 2, 3, 5- trimethynaphthalene (0.82 mg/kg) in that order (table 3). Sample S2, a jollof rice also contained most of the PAH totaling 9.8 mg/kg, with the usual presence of two strong carcinogens which are benzo (b) fluoranthene and dibenz (a, h) anthracene with concentrations 0.12 mg/kg and 0.76 mg/kg respectively. The order of concentration was 2-methylnaphtalene (5.21 mg/kg) > 2, 3, 5- trimethynaphthalene (1.03 mg/kg) > benzo (g, h i) pyrylene (0.87 mg/kg) >dibenz (a, h) anthracene (0.87 mg/kg) etc. (table3). Sample S3 also recorded similar trend of concentration ranging from <0.02

8 6.77 mg/kg. 2-methylnaphtalene (6.77 mg/kg) recorded the highest concentration with 2, 3, 5- trimethynaphthalene (1.08 mg/kg), benzo (g,h,i) pyrylene (0.83 mg/kg), benzo (e) pyrene (0.64 mg/kg) and pyrene (0.62 mg/kg) followed respectively (table 3). Lower levels of PAHs were recorded for sample S4 and S6 with the highest values of 1.05 and 0.53 mg/kg respectively (< and < mg/kg) respectively (table 3). Sample S5, S7, S8, S9 and S10 also had elevated levels of PAHs. The ranges are as follows: < mg/kg, < mg/kg, < mg/kg, < mg/kg and < mg/kg respectively. Again 2-methylnaphtalene recorded the highest values in all of these samples S5, S7, S8 and S9 (table 3). The result has shown that PAHs are indeed present in the charred portion of rice popularly known in Ghana as under or kanzou. This portion of rice is highly patronized in Ghana because it is cheap thereby exposing consumers to the dangerous health effect of PAHs. Table 2: Mean concentrations of control and rice samples from vendors Compound Controlled rice Samples from vendors Uncooked mg/kg Charred (cooked by researcher) Charred Rice (collected from vendors) Standard Deviation Variance Ave. mg/kg Ave. mg/kg Naphthalene nd Methylnaphthalene Methylnaphthalene nd Biphenyl nd nd nd 0 0 2,6-Dimethylnaphthalene nd Acenaphthylene Acenaphthene ,3,5-Trimethylnaphthalene Fluorene Phenanthrene Anthracene Methylphenanthrene

9 Fluoranthene Pyrene Benzo(A)Anthracene Chrysene nd nd nd 0 0 Benzo(B)Fluoranthene Benzo(K)Fluoranthene nd nd nd 0 0 Benzo(E)Pyrene Benzo(A)Pyrene nd nd nd 0 0 Perylene nd nd nd 0 0 Indeno(1,2,3-Cd)Pyrene nd nd nd 0 0 Dibenz(A,H)Anthracene Benzo(G,H,I)Perylene Total [nd = <0.02 mg/kg] Carcinogenic and Non Carcinogenic Risk assessment The US EPA carcinogenic risk assessment guidelines version 4.0, had been used to assess the level of hazard and cancer risk for some of the PAH compounds detected which are of concern to human health. Though the format for vegetable was used under environmental conditions, extrapolating it with the assumption that vegetable is ingested as a food substance just like rice. The quantification of constituent of concern (COC s) from ingestion of rice for residential adult exposure scenario is calculated using US EPA risk assessment model (US EPA, 1989; 1997; Obiri et al., 2006). Parameters used in addition to detected concentration of PAH were an adult of age 70years, with 70kg weight and consuming 127kg of rice. Assuming same for rice, a summary of chronic hazard for central tendency exposure (CTE) ranges from a minimum of 7.9E-08 to a maximum of 9.1E-05 and that for reasonable maximum exposure (RME) also ranged from a minimum of 2.0E-07 to a maximum of 2.3E-04. Acute hazard for CTE ranges from a minimum of 2.8E-05 to a maximum of 2.6E-07 and that for RME from a minimum of 6.9E-05 to a maximum of 6.5E-07. The interpretation follows the same as was explained for the chronic hazard (table 4). The values as compared to USEPA s acceptable criteria value of one (1) (USEPA, 1995) may not pose any health hazard to consumers of such portion of rice. A summary of chronic carcinogenic risk for CTE ranged from a minimum of 2.2E-08 to a maximum of 4.4E-07 and that for RME also ranged from a minimum of 5.4E-08 to a maximum of 3.7E-06.

10 Acute carcinogenic risk for CTE ranges from a minimum value of 4.8E-10 to a maximum value of 9.9E-09 while that for RME is from a minimum of 1.2E-09 to 2.5E-08 (table 5). Though comparing these values to the U.S EPA accepted figure of 1.0E-06 to 1.0E-04 (one out of one million to one out of ten thousand people may suffer from cancer related cases), it is insignificant, but it becomes significant to an individual if he or she has cancer. From the result a total maximum of 4 out of 10,000,000 people may suffer from various forms of cancer in the case of chronic situation for CTE, while in the case of RME 4 out of 1,000,000 people may suffer from various forms of cancer. In the case of acute scenario for CTE, a maximum total of 10 out of 1000,000,000 people would suffer from various forms of cancer related cases, while in RME, 3 out of 100,000,000 individual may suffer from various cancer related cases (table 5). In any case, it may contribute a little to the numerous cancer (breast and cervical) cases in Ghana as stated by Awuah et al, (2004) and Adams, (2005). Table 4: Summary of Hazard Quotients COMPOUND CHRONIC EXPOSURE ACUTE EXPOSURE CTE RME CTE RME ACENAPHTHENE 1.1E E E E E E E E-06 ANTHRACENE 6.6E E E E E E E E-07 FLUORANTHENE 2.6E E E E E E E E-06 FLUORENE 5.5E E E E E E E E-06 NAPHTHALENE 3.2E E E E E E E E-05 PYRENE 2.7E E E E E E E E-05 TOTAL 7.9E E E E E E E E-05 Table 5. Summary of Carcinogenic Risk COMPOUND CHRONIC EXPOSURE ACUTE EXPOSURE CTE RME CTE RME Benzo(a) Anthracene 2.6E E E E E E E E-10 Benzo(b) Fluoranthene 3.4E E E E E E E E-09 Benzo(k) Fluoranthene 0.0E E E E E E E E-13 Dibenz(a,h) Anthracene 1.6E E E E E E E E-08 TOTAL 2.2E E E E E E E E-08 CTE = central tendency exposure, RME = reasonable maximum exposure NOTE: A zero hazard index may indicate that an RfD was not entered for that chemical

11 Source Characterization Site Correlations Correlation analyses between the location points of samples (vendors) of individual PAH compound levels (n = 73) table 6, indicates fairy to strong significant correlation between location points suggesting a common source of origin of PAHs from these sites (McRae et al. 2000). The highest correlation observed as S3/C3, S3/C4 and C3/C4 (1.00) followed by S2/S5 (0.995), S5/C3, S5/C4 and S3/S5 all having at 0.01 level. Other strong positive correlations recorded are: S2/C3, S2/C4 and S3/S2 (0.988), S8/S7 (0.981), S9/S7 (0.979), S9/S8 (0.969) and S10 correlating with S6, S7, S8 and S9 in the range of all at 0.01 levels (table 6). Other non strong correlations at 0.05 levels were also seen among the samples like S1/C4, S4/C1, S6/C2, S10/S3 etc. table 6. The correlation between the various samples of the individual PAH compounds is also reflected in the similarities of the compositional patterns of the various samples. However, despite the different approach of preparation of these samples their correlations suggest a very strong common source which could be the cooking process. Some few fairly correlations was seen between mildly burnt cooked plane rice samples such as S5/S8 (0.404), S6/S8 (0.569) and S6/S10 (0.537) all at 0.01 level. But most of them did not show any form of correlation which demonstrate different form of origin. It could be inferred from the correlation pattern that jollof rice burnt and plane rice burnt correlated strongly in most cases as seen in table 6 (S9/S10, S8/S10, S7/S10 etc). This clearly explains the early accession that burning process used in cooking could be the main source of PAHs in the rice used in this study. Controlled samples burnt plane rice (C2, C3 and C4) correlated 100% with the Jollof rice ie. a mixture of more brown and black burnt cooked rice (C3/S3) and strongly correlated positively with Jollof rice, a mixture of black and brown burnt cooked rice (S2/C4 and S3/C3) all at 0.01 levels. This shows that the source of PAHs may mainly be from anthropogenic source, typically of cooking processes. PAH Interrelationships In order to assess PAH associations and their possible origins, correlation analyses were conducted among the concentration of the individual PAHs in the various rice samples. The results are summarized in table 7. It is known that where two compounds have a common source, there is more likely to be a correlation between their concentrations (Gilbert 2006). Fairly positive significant correlation was observed between individual PAHs. Pyrene and 1-Methylphenanthrene showed the highest PAH interrelationship with correlation coefficient of followed by 2,3,5- Trimethylnaphthalene/1-Methylphenanthrene and Pyrene/2-Methylphenanthrene correlated with and respectively, significant at 0.01 levels. The following pairs also interrelated weakly at the significant level of 0.01: 1-Methylphenanthrene/2-Methylphenanthrene (0.488), Fluorine/2- Methylphenanthrene (0.434), 2-Methylphenanthrene/Fluoranthene (0.346), acenaphthylene/1- methylphenanthrene (0.396), 1-Methylphenanthrene/Fluorine(0.504), acenapththene/2,6- dimethylnaphthalene (0.415), benzo(e)pyrene/ 2,3,5-Trimethylnaphthalene (0.496), Phenanthrene/Fluoranthene(0.417) and Phenanthrene/ Anthracene significant at 0.01 levels table 7.

12 In another development very fairly interrelationship was also observed between pairs of PAHs significant at 0.05 levels, the highest of which is Phenanthrene/ Acenaphthylene (0.392) followed by anthracene/ Acenaphthylene (0.376) and the least been Benzo (ghi) perylene/2,6- Dimethylnaphthalene (0.272) (Table 7). The results reveal that these compounds, and to a lesser extent pyrene, were possibly derived from a common anthropogenic origin ie. Pyrogenic sources (arises from those formed during the incomplete combustion of coal, oil, gas wood and garbage) (Gabos et al., 2001; Duke, 2008). The weak interrelationship is well noted since PAHs formation mainly is markedly based on the conditions (temperature) under which it was formed. However, it could be explained that the weak correlation may be due to temperature variations and the method of cooking which are generally the primary determinant of the PAH content (CCME, 2008). One must not forget the use of liquefied (LPG) gas in almost all the sampling sites for cooking the rice samples could have also contributed to some PAHs accumulation, as combustion of fuels and coal has caused widespread environmental PAH contamination on a global scale in association with atmospheric transport pathways (CCME, 2008). No significant correlation was identified between benzo (a) anthracene (BZA) compound with any of the other PAH compounds measured which indicate other source of this PAH. Benzo (b) fluoranthene (BZBF) showed inverse correlation with 2-Methylphenanthrene (at 0.01 level), 2,3,5- Trimethylnaphthalene (TMNAP) and 1-Methylphenanthrene both at 0.05 levels (table 7). Dibenz (a,h) anthracene (Dib) also showed inverse correlation with Acenapththene also at 0.01 levels and Benzo (e) pyrene significant at 0.05 levels. PAH Isomer Pair Ratios as Diagnostic Source Indicators The ratios of the above-specified PAHs in the cooked and uncooked rice are tabulated in table 8. The ANTR/ANTR+PHT ratios are all >0.35, suggesting combustion sources of PAH. The only exception is the sample C1 and S10 (a control uncooked perfume rice) which demonstrated petroleum origin which has been strongly linked to its origin of production. PHT /ANTR ratios are almost all > 3 which shows that source of PAHs from all the samples sites does not come from gasoline exhaust or coal combustion or wood burning (Simcik et al 1999). In another development, the ratio of BZghi/BZeP was also accessed to confirm traffic contribution of the PAHs. BZghi/BZeP ratios of C1, C1, S6, S8 and S10 where all gave values < 0.8 indicating non-traffic source contribution of PAHs while S4 recorded ratio of 2.77 which demonstrate 100% contribution of traffic source of PAHs (Nielsen 1996, Nielsen, et al. 1996). Despite the lack of consistency in some cases, there seems to be a general consensus by all the ratio indicators that combustion and pyrolysis is the dominant source of PAH input into the rice (Yunker et al 2002; Pathiratne and DeSilva, 2007). Although not conclusive, there is also an indication of petrogenic source contributions, may be from the fuel used in cooking the rice which is usually liquefied petroleum gas (LPG). Variations in additional input sources (e.g., high or medium temperature combustion processes, different fossil materials) may also account for the differences in the composition pattern of PAHs between sampling sites (table 8) (Zhou and Maskaoui, 2003).

13 Conclusion Results obtained from the study indicates that uncooked rice contain some carcinogenic PAH compounds. Vegetable oil in addition to combustion process used in jollof rice preparation may have contributed to high levels of PAH in the cooked rice. Partially burnt rice shows high levels of PAH than more burnt ones since the highly burnt ones may be near to complete combustion. It was also realized from the study that pretreatment of rice by washing removes some level of contaminants therefore rice should be washed properly before cooking. Also, the heat source should be properly regulated to minimize the charred portion of the cooked rice. If possible the charred portion should not be eating. The results also showed the presence of strong carcinogens like benzo(a)anthracene, benzo(b)fluoranthene and dibenz(a,h)anthracene as well as a moderate carcinogen; benzo(e)pyrene in almost all the samples. Though other carcinogens were detected, including those used in the U.S EPA risk assessment guidelines; the above stated ones are the most serious ones in relation to their classification. The study also showed that temperature was a variable factor which resulted in the different levels for each PAH compound in the various samples. The study demonstrated that biphenyl, chrysene, benzo (a) pyrene, benzo (k) fluoranthene, perylene and indeno (1, 2, 3-cd) pyrene were not detected in any of the samples analyzed. The U.S EPA carcinogenic and non carcinogenic risk assessment used indicated lower significant values compared to the U.S EPA acceptable limits of 1.0E-04 to 1.0E-06. Finally, despite the lack of consistency in some cases, there seems to be a general consensus by all the ratio indicators that combustion and pyrolysis is the dominant source of PAH input into the rice. Acknowledgment The author wishes to express his sincere appreciation to all the students who supported this work. Also, to the staff of Centre for Scientific and Industrial Research, (CSIR) Environmental Division (ED), Water Research Institute (WRI) and the Organic Laboratory for their kind assistance in the analysis of the samples. Sincere thanks also go to the entire laboratory staff of the Chemistry Department University of Cape Coast for their support. Finally, we wish to thank the government of Ghana for financial assistance. References Adams M Number of cancer cases in Ghana rises dramatically, naturalnews.com Alomirah H, Al-Zenki S, Husain A, Sawaya W, Ahmed N, Gevao B. and Kannan K Benzo[a]pyrene and total polycyclic aromatic hydrocarbons (PAHs) levels in vegetable oils and fats do not reflect the occurrence of the eight genotoxic PAHs. Food Add. Contaminants: Part A 1 10,

14 ATSDR Agency for toxic substances and diseases registry Toxicological Profile Information Sheet. Awuah E, Oppong-Preprah M, Lubberding HJ, Gijzen HJ Comparative performance studies of water lettuce, Duckeed, and algal-based stabilization ponds using Low-strength sewage. Journal of Toxicology and Environmental Health 67: Badger GM Mode of formation of carcinogens in human environment. Nat. Cancer Inst. Monogr. 9: 1 Bostron CE, Gerde P, Hanberg A, Jernstrom B, Jahansson C, Kyrklund T, Rannug A, Tornqvist M, Victorin K, Westerholm R Cancer risk assessment, indicators, and guidelines for polycyclic aromatic hydrocarbons in the ambient air. Environmental Health Perspectives 110: CCME (Canadian Council of Ministers of the Environment) Canadian Soil Quality Guidelines for Carcinogenic and Other Polycyclic Aromatic Hydrocarbons (Environmental and Human Health Effects). Scientific Supporting Document. 218 pp. Joint FAO/WHO Food Standards Programme: Codex Committee on Food Additives and Contaminants, 37th session; Agenda 17h. Concon JM Endogenous toxicants in foods derived from higher plants, In Food and Toxicology, parts A & B, Marcel Dekker Inc, USA, pp , Davis CS, Fellin P, Otson R A review of sampling method for polyaromatic hydrocarbon in air. Journal of the Air Pollution Control Association 37: Deshpande SS Handbook of food toxicology, CRC Press. New York; p Duke O Source determination of polynuclear aromatic hydrocarbons in water and sediment of a creek in the Niger Delta region. African Journal of Biotechnology 7 (3): EUSCF Scientific Committee on Food (SCF), European Commission, Opinion of the Scientific Committee on Food on the risks to human health of polycyclic aromatic hydrocarbons in food European Commission Regulation (EC) No. 208/2005. Furihata C, Matsushima T Mutagens and carcinogens in Foods; Ann. Rev. Nutr. 6; Gabos S, Ikonomou, MG, Schopflocher D, Fowler BR, White J, Prepas E, Prince D, Chen W Characteristics of PAHs, PCDD/Fs and PCBs in sediment following forest fires in northern Alberta. Chemosphere 43: Gilbert E, Dodoo DK, Okai-Sam F, Essumang DK, Quagraine EK Characterization and source assessment of heavy metals and Polycyclic Aromatic Hydrocarbons (PAHs) in sediments of the Fosu Lagoon Ghana Journal of Environmental Science and Health Part A, 41;

15 Gray, J. (Ed), The Connection between Breast Cancer and the Environment: State of Evidence 5th Ed.: Cooperative Printing, Minneapolis p 1-127, the Grimmer G, Boehnke M Polycyclic aromatic hydrocarbons profile analysis of highprotein foods, oils and fats by gas chromatography. J AOAC Int. 58: Kanchanamayoon W, Tatrahun N Extraction of eleven polycyclic aromatic hydrocarbons in water samples, Journal of Environmental Science and Technology, 2 (2); Kazerouni N, Sinha R, Che-Han H, Greenberg A, Rothman N Analysis of 200 food items for benzo[a]pyrene and estimation of its intake in an epidemiologic study. Food and Chemical Toxicology 39 (5); Liu X, Korenega T Dynamics analysis for the distribution of polycyclic aromatic hydrocarbons in rice. Journal of health science 47(5): McRae, C, Sun CG, McMillan C, Snape CE, Fallick AE Sourcing of fossil Derived PAH in the environment. Poly. Arom. Comp., 20: Nielsen, T Traffic contribution of polycyclic aromatic hydrocarbons in the center of a large city. Atmospheric Environment 30: Nielsen T. Jørgensen, H. E. Larsen, J. Chr. Poulsen, M. (1996). City air pollution of polycyclic aromatic hydrocarbons and other mutagens: occurrence, sources and health effects. The Science of the Total Environment 189/190, Obiri S, Dodoo DK, Okai-Sam F, Essumang DK, Adjorlolo-Gasokpoh A Cancer and Non cancer health risk from eating cassava grown in some mining communities in Ghana, Environmental Monitoring and Assessment 118: Pathiratne KAS, DeSilva OCP Occurrence and Distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in Bolgoda and Beira Lakes, SriLanka. Bull Environ Contam. Toxicol. 79: Shen M, Chapman RS, Xingzhou H, Lai LZLH, Chen W, Lan Q Dietary factors, food contamination and lung cancer risk in Xuanwei, China. Lung Cancer, 61(3): Simko P Determination of polycyclic aromatic hydrocarbons in smoked meat and smoke flavouring food additives. J. Chromatogr. B. 770: Toth L, Potthast K Chemical aspects of the smoking of meat and meat products. Res., 29, products Adv. Food US EPA (Environmental protection Agency), Exposure Factors Handbook. Generalfactors. Office of Research and Development, Washington, D.C.

16 USEPA (US Environmental Protection Agency). Risk Assessment Guidance for Superfund (RAGS), vol 1, Human Health Evaluation Manual (Part A). OWSER Directive A. EPA 540/ Office of Emergency and Remedial Response Washington, DC, USA USEPA Superfund Record of Decision: Record of Decision Harris Corporation/Palm Bay Facility Site USA. Directive EPA/ROD/R04-95/211. FLD Office of Solid Waste and Emergency Response, Washington, DC, USA Wilson EG West African Cookbook; Harper Collins Publishers, New York, p Yunker MB, Macdonald RW, Vingarzan R, Mitchell RH, Goyette D, Sylvestre S PAHs in the Fraser River basin; a critical appraisal of PAH ratios as Indicators of PAH source and composition. Org. Geochem., 33: Zhou JL, Maskaoui K Distribution of polycyclic aromatic hydrocarbons in water and surface sediments from Daya Bay, China, Environmental Pollution, 121; Zhu, L.; Wang, J. Pattern and Sources of PAHs poluution in Sediment of Hangzhou, China. Organohal. Comp. 2004, 66,

17 Table 3: Concentration of PAHs of control and rice samples from vendors COMPOUND Concentrations in mg/kg Standard Deviation Variance C1 C2 C3 C4 S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 Ave NAPHTHALENE nd 0.02 nd 0.02 nd nd 0.02 nd 0.03 nd METHYLNAPHTHALENE nd METHYLNAPHTHALENE nd nd BIPHENYL nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd 0 0 2,6- DIMETHYLNAPHTHALENE nd ACENAPHTHYLENE ACENAPHTHENE ,3,5- TRIMETHYLNAPHTHALENE FLUORENE 0.02 nd nd PHENANTHRENE nd ANTHRACENE nd METHYLPHENANTHRENE FLUORANTHENE PYRENE BENZO(a)ANTHRACENE assessment and source characterization. Journal of Basic & Applied Sciences, 1 (2), 63-83

18 nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd 0 0 CHRYSENE BENZO(b)FLUORANTHENE BENZO(k)FLUORANTHENE nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd 0 0 BENZO(e)PYRENE BENZO(a)PYRENE nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd 0 0 PERYLENE nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd 0 0 INDENO(1,2,3-cd)PYRENE nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd 0 0 DIBENZ(a,h)ANTHRACENE 2.54 nd nd nd BENZO(g,h,i)PERYLENE TOTAL [nd = <0.02mg/kg] Table 6. Summary of Correlation coefficients of PAH from different location points. (n =73) C1 C2 C3 C4 S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 C ** * C **.419**.574**.384**.419**.546**.418**.433* C **.389*.988** 1.000**.428**.992** *.451**.420**.386* C *.988** 1.000**.428**.992** *.451**.420**.386* S **.389*.347*.357*.379* S **.448**.995** *.387*.351*.339* assessment and source characterization. Journal of Basic & Applied Sciences, 1 (2), 63-83

19 S **.992** *.451**.420**.386* S ** S *.404**.381**.342 S **.569**.642**.537** S **.979**.881** S **.888** S ** S10 1 **. Correlation is significant at the 0.01 level (1-tailed). *. Correlation is significant at the 0.05 level (1-tailed). Table 7. Summary of Correlation coefficients for PAHs compounds in the rice samples for 14 different sources (n = 42) NAP 2-MNAP 1-MNAP DMNAP ACL ACT TMNAP FLU PHTR ANTR MPH FLT PYR BZA BZBF BZeP DIB BZghi NAP 1 2-MNAP MNAP ** 1 DMNAP ACL ** ACT **.287* 1 TMNAP ** FLU **.504** PHTR * * ** 1 ANTR * * ** 1 MPH **.338* FLT * * *.356* assessment and source characterization. Journal of Basic & Applied Sciences, 1 (2), 63-83

20 PYR **.553** * * BZA BZBF ** * * BZeP ** ** DIB ** * 1 BZghi * **. Correlation is significant at the 0.01 level (1-tailed). *. Correlation is significant at the 0.05 level (1-tailed). Table 8. Summary of PAH ratios of rice samples from sampling sites. Ratio This work Source Patterns from the literature C1 C2 C3 C4 S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 ANTR/(ANTR+PHT) >0.10: comb. Source; <0.10: Petr. source (Yunker et al 2002, Zhu et al 2004) PHT /ANTR : gasoline exhaust; 3: coal comb. & wood burning (Simcik et al 1999 ) FLT/(FLT+PYR) >0.50: biomass & coal comb : Petr. comb. assessment and source characterization. Journal of Basic & Applied Sciences, 1 (2), 63-83

21 <0.40: unburned petr. (Yunker et al 2002, Zhu et al 2004) ( BZghi)/BZeP : non- traffic source; 2.02 traffic (Nielsen, T. 1996, Nielsen, et al. 1996) Compound abbreviations in Table 5. assessment and source characterization. Journal of Basic & Applied Sciences, 1 (2), 63-83

22 Appendix I Table 9: The listed codes and description for the samples (sale points) Samples collected from local vendors Rice cooked by the researcher Jollof rice Plain rice Control Rice S1 = Jollof rice, a mixture of black and brown burnt cooked rice from Marian s point at Teshie S5= Plain rice, mildly burnt from Vida s point at Ashaiman C1= Control Uncooked perfumed rice S2= Jollof rice, a mixture of black and brown burnt cooked rice at Barbara s point at Tema S6= Plain rice mildly burnt from Amina s point at Tema station, Accra C2= Control Cooked Perfumed rice S3= Jollof rice, a mixture of more brown and black burnt cooked rice from Vida s point at Ashiaman S8= Plain rice, mildly burnt from Registrar General s point, Accra. C3= Control Mildly burnt cooked Perfumed rice. S4= Jollof rice, a mixture of black and brown burnt cooked rice from Anim s point at Ashaiman S10= Plain rice, black burnt rice from Hoffman s point, Tema C4= Control Burnt Jollof rice of perfumed rice S7= Jollof rice, a mixture of dark burnt rice from Gify s point at Kaneshie Accra. assessment and source characterization. Journal of Basic & Applied Sciences, 1 (2), 63-83