The Presence of Polycyclic Aromatic Hydrocarbons (PAHs) in Grilled Beef, Chicken and Fish by Considering Dietary Exposure and Risk Assessment

In this study, chemicals that were used as follows: a mixture of PAH calibration standards (CRM 47940, Sigma-Aldrich, St. Louis, MO, USA), Acetonitrile (1.00030, Merck, Darmstadt, Germany) and Methanol (1.06007, Merck). 1, 2, 5, 10, and 20 mg/L calibration standards were prepared using the main stock solution of 2,000 mg/L (methanol/acetonitrile) of PAH calibration standard blends. Prepared stock standard solutions were stored in dark glass vials and at 4°C.

In this study, a total of 100 samples consisting of 20 randomly chosen meat doner, chicken doner, meatballs, grilled chicken and fish were used as materials. Each sample was analyzed in 3 repetitions. Samples were taken between March and June 2017 from different restaurants in Sivas, Turkey. Samples were brought to the laboratory under cold chain at 4°C and samples that would not be analyzed immediately were stored in the freezer −20°C (Table 1).

The method proposed by Farhadian et al. (2010) for sample preparation before HPLC analysis was applied with some minor modifications. Firstly, the main reagents of the method, Carrez I and Carrez II solutions were prepared according to literature. In chromatographic analysis for each sample type, a part of PAH calibration standard was spiked to control samples in order to determine the location of the peaks and the reliability of the analysis (PAH Calibration Mix 47940, Sigma-Aldrich).

For Carrez solutions, 10.6 g potassium ferrocyanide [K₄Fe(CN)₆·3H₂O] (1.04984, Merck) was weighed for Carrez I solution and dissolved in distilled water to 100 mL. For Carrez II solution, 21.9 g zinc acetate Zn(CH₃COO)₂·2H₂O was weighed, 3 mL of acetic acid (CH₃COOH) was added and completed to 100 mL with distilled water. The prepared solutions were stored in dark glass bottles and at 20°C.

Then, about 50.0 g samples were homogenized and weighed 3.0 g from each sample. It was added from a mixture of 10 mL of 1 M KOH and 10 mL of Methanol/Acetonitrile (50:50) on samples. The tubes were closed and mixed, vigorously. Then, it was kept in ultrasonic water bath at 40°C for 10 min. The tubes were then shaken at 2×g for 30 min in orbital shaker and the organic content was transformed into the solution phase. After waiting for 10 min at 40°C in ultrasonic water bath, the tubes were centrifuged at 4,200×g for 5 min. After this process, the solid and liquid phases were separated from each other and the liquid phase was taken to another tube. Then, 1.3 mL of 6 M HCl was added to the liquid phase and the pH was adjusted to 6 then 1 mL Carrez 1 and 1 mL Carrez II solutions were added. After the tubes were thoroughly shaken, they were centrifuged at 4,200×g for 5 min. The 1.5 mL sample from the upper phase after centrifuge was filtered with 0.45 μm syringe tip filters and transferred to HPLC vials.

The HPLC system were consisted of Shimadzu HPLC High Performance Liquid Chromatography (Shimadzu, Kyoto, Japan) and SPD-10AD DAD Detector (Shimadzu) at a flow rate of 1 mL/min and column temperature of 30°C. The injection volume for the samples was set at 10 μL, and wavelength 256 nm. Luna Omega C18 HPLC column (250 mm×4.6 mm, 5 μm) from Phonemex (California, USA) chromatographic column was used to separate the analytes. Eluents were filtered through 0.45 μm microporous membrane and degassed under ultrasound for 15 min before use.

The mobile phase composition was MeOH:ACN:pH 6.0 phosphate buffer (40:10:50) at isocratic mode throughout analysis. The detector wavelength was operated at 256 nm for all PAH molecules. Peaks in the chromatograms were identified by comparison with retention times and UV spectra of standards. Peak area was considered for quantification. All data were recorded using the above described chromatographic conditions. The obtained chromatogram under the optimum conditions was given in Fig. 1. The retention time of each compound was plotted with their names.

Fig. 1. Chromatogram of PAH mix standart. PAHs, polycyclic aromatic hydrocarbons.

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Analytical validation of the analysis method was partly carried out by using experimental studies. Firstly, linear range, limit of detection (LOD) and limit of quantitation (LOQ) values were calculated for each PAH compounds by considering experimental observations. Linearity was checked by constructing the calibration curves using spiked model solutions at 6 concentration levels. Calibration curves were obtained by graphing peak area of each PAH molecules versus its concentration. Linear regression analysis was used to calculate the slope, intercept and the correlation coefficient of each calibration line. The results were presented in Table 2. Accuracy expressed as percentage recovery was calculated from the found mass of the analyte on the spiked sample toward added mass after replicate analysis of spiked samples at various concentrations. Recovery values were found in the range of 95.3%–104.8% for PAH molecules.

The exposure of consumers to PAH was assessed by daily meat consumption, depending on the levels of contamination obtained in this study. Data on meat consumption were obtained from the Meat and Milk Board of Turkey and the daily consumption amount was determined (MMB, 2018). The body weight of an adult person was taken as 70 kg and this value was used in the calculations (Türkmen et al., 2009). Estimated daily intake (EDI) was calculated using the following formula (Bogdanović et al., 2019): (Eq. 1):

Where,

EDI: ng/kg body weight per day

Ci: for the mean concentration of PAH or combination of PAHs (μg/kg)

Cc: the daily average consumption of meat per person (g)

BW: for the body weight (kg) of the consumer

In this study, five different meat samples consisting of meat doner, chicken doner, meatballs, grilled chicken, and fish, which are offered for consumption by heat treatment at different restaurants in Sivas, were analyzed using HPLC method to determine the level of PAH compounds (Table 1). In this study, a developed and approved (validated) method was used for quantitative analysis of 16 PAH compounds in heat treated meat samples (Table 2).

Known as the most important PAH compound, BaP is considered an indicator in determining the level of PAH (EFSA, 2008). In this study, the level of BaP in meatball and grilled fish samples was 0.70 and 0.73 μg/kg, respectively. The presence of BaP was not detected in heat treated meat doner, chicken doner, and grilled chicken samples (Table 3). The technique of cooking the meat can differ in terms of PAH formation (Lee et al., 2016). In one study, two different geometric cooking techniques were compared in meat and fish samples. It has been reported that the amount of PAH formed by the oil dripping directly into the source of fire in the horizontally cooked meat occurs more than cooked in a vertical position (Saint-Aubert et al., 1992). In this study, meatballs and grilled fish samples were cooked horizontally and in the charcoal flame. Interestingly, although it was cooked horizontally on the grill and in a charcoal fire, there was no presence of BaP in the grilled chicken samples due to the lack of skin on the breast used in the grilled chicken. During grilled cooking, the oils, which are primarily located on the outer surfaces of the meat and come into direct contact with flame, melt and contribute to the formation of PAHs by dripping on the fire. Lee et al. (2016) in their research in Korea were cooked beef on a barbecue and used a design to prevent meat oil from dripping onto the flame. As a result, 3.23 μg/kg BaP was detected as a result of cooking the beef on the grill on the charcoal fire, while 0.78 μg/kg BaP was determined in the system where the oil dripping was prevented. In a study conducted in Turkey, Terzi et al. (2008) investigated BaP levels in samples of doner kebabs cooked in charcoal and gas fire. In the samples cooked in charcoal fire, they found the average amount of BaP as 24.2 μg/g and 5.7 μg/g in samples cooked in the gas flame. In this study, meat and chicken doner samples were cooked vertically on the electric grill and the presence of BaP was not detected.

When roasted beef, turkey, lamb, and chicken meats were evaluated in terms of PAH4 (BaP, BaA, BbF, and Chr) concentration, it was reported that differences were observed according to the type of meat and PAH type (Aydın and Şahan, 2018). Aydın and Şahan, (2018) in their study evaluated meat samples in terms of PAH4; they determined the highest amount of PAH4 in chicken meat (3.30 ppb), followed by turkey (3.14 ppb), lamb (1.74 ppb) and beef (1.10 ppb). They stated that the reason for this difference may be due to the difference in the chemical composition of meats. In this study, PAH4 (BaP, BaA, BbF, and Chr) concentration was evaluated according to meat products; the lowest PAH4 amount (1.95 μg/kg) was determined in meatball samples, and the highest PAH4 (3.30 μg/kg) was determined in grilled fish samples. Olatunji et al. (2013) stated that total PAH concentrations in grilled chicken fillets and beef stripes were 0.99, 9.29 μg/kg, respectively. In accordance with this study, Kim et al. (2014) in their study in Korea were reported that they found the amount of PAH4 in fish samples as 0.19 μg/kg. Researchers reported that levels obtained from fish samples were below the EU’s limit in terms of both BaP (5 μg/kg) and PAH4 (30 μg/kg). The results of this study were evaluated in accordance with the Turkish Food Codex Food Contaminants Regulation and the European Union Directive (EU, 2011; TFC, 2011). In the relevant regulation, the maximum limit for PAH compounds of BaP in the meat and meat products analyzed is 5 μg/kg and for PAH4 is given as 30 μg/kg. The analyzed meat doner, chicken doner, meatballs, grilled chicken and fish samples were all found to be below the permitted limits for BaP and PAH4 compounds (Table 3).

When the PAH compounds were evaluated individually, the presence of Ant, which is one of the light PAHs (LPAHs include: Nap, Ace, Ane, Fle, Phe, Ant, Flu, and Pyr), was found in all meat samples. In meat doner, chicken doner, meatballs, grilled chicken and fish samples, the presence of Ant was found to be 0.95, 1.07, 0.93, 0.87, and 0.97 μg/kg, respectively. A study by Hamzawy et al. (2016) in Egypt reported a similar result in meat (0.90 μg/kg) and grilled chicken (0.67 μg/kg) samples related to the presence of Ant.

The presence of BkF, BbF, and Chr, which are heavy PAH (HPAHs include: BaA, BaP, BbF, BkF, Chr, DahA, BghiP, and IcdP) were detected in all meat samples. Among the heavy PAH compounds, the amount of BkF in grilled fish samples was found to be highest at 0.91 μg/kg, while the amount of BbF was 0.77 μg/kg and Chr was 0.63 μg/kg. In grilled fish samples, BaP concentration was found as 0.77 μg/kg and did not exceed the maximum allowable limit of 5 μg/kg. PAH8 which includes heavy PAHs, also known as genotoxic PAH, was found to be above 5 μg/kg. In a study conducted by Alomirah et al. (2011), the average BaP level in smoked fish samples was 0.50 μg/kg and did not exceed the limit value, but genotoxic PAH8 was found to be 10.3 μg/kg (7.58–12.9 μg/kg) which was above the allowable (5 μg/kg) value. These results also showed that BaP is not a good indicator as a carcinogenic and genotoxic PAH compound alone (Alomirah et al., 2011; EFSA, 2008).

The formation of each PAH compounds and the average level of contamination in all heat treated meat products (meat doner, chicken doner, meatballs, grilled chicken, and fish) are given in Table 3. In five different meat samples (meat doner, chicken doner, meatballs, grilled chicken, and fish), the total level of PAH (Σ16PAH) was 6.08, 4.42, 4.45, 4.91, and 7.26 μg/kg, respectively. Jiang et al. (2018) in their study in China were found the contamination level of Σ15PAH between 12.0–341.0 μg/kg and the average level was 80 μg/kg in grilled meat samples. Duedahl-Olesen et al. (2015) in their study in Denmark were found the concentration of Σ16PAH in barbecued beef (steak) and chicken breast as 10.2 and 6.3 μg/kg. In a study conducted by Alomirah et al. (2011), Σ16PAHs level was in the range of 48.2–342.0 μg/kg in grilled chicken meat, with an average of 222 μg/kg. PAHs are caused by pyrolysis or incomplete combustion of organic material during cooking of meat at high temperatures (Alomirah et al., 2011; Farhadian et al., 2010; Jiang et al., 2018). Chung et al. (2011) were investigated that roasted and baked cattle, chicken and pork meat contained PAH, and reported that the charcoal grill caused the highest PAH levels. They found that the samples of chicken meat grilled in a charcoal fire contained the highest level of Σ PAHs (9.46 μg/kg). For this reason, in grilled meats cooked in a charcoal fire, PAHs are formed depending on the amount of fat contained in the meat, the cooking temperature and duration (Aydın and Şahan, 2018; Chung et al., 2011; Duedahl-Olesen et al., 2015; Jiang et al., 2018; Lee et al., 2016).

Estimates of the daily dietary PAH, PAH4, PAH8, and Σ₁₆PAH intakes of adult people from meat products (meat doner, chicken doner, meatballs, grilled chicken and fish) were given in Table 4. Daily intake estimates of individual PAH compounds in meat doner samples were 0.13 to 0.72 ng/kg bw/day on average, while exposure for PAH4, PAH8, and Σ16PAH was estimated as 1.24, 1.78, and 3.41 ng/kg bw/day, respectively. For grilled fish samples, daily intake estimates of individual PAH compounds were 0.03 to 0.24 ng/kg bw/day, PAH4, PAH8, and Σ16PAH exposure were 0.80, 1.25, and 1.77 ng/kg bw/day. In addition, the average daily BaP intake for adults was 0.39 ng/kg bw/day and 0.18 ng/kg bw/day in meatball and grilled fish samples. According to the EFSA (2008) stated that the average amount consumers will be exposed to for meat and meat products for member states is 132 g/day, while for BaP, PAH4, and PAH8, it is 42, 195, and 279 ng/day, respectively.

Estimated dietary intake of PAH compounds has been compared with previous studies. In one study, the average dietary intake of BaP and PAH8 in grilled and smoked meat products by Kuwaiti people was found to be 9.20 and 95.7 ng/day (Alomirah et al., 2011). Kim et al. (2014) were stated in their evaluation that the average dietary intake of Korean people in all age groups from fish and shellfish for BaP, PAH4, and PAH8 was 0.01 ng-TEQBaP/kg/day, 0.01 ng-TEQBaP kg/day and 0.01 ng TEQBaP kg/day. In the same study, exposure to meat products was determined as 0.15 TEQBaP/kg/day, 0.29 TEQ BaP/kg/day and 0.54 TEQBaP/kg/day for BaP, PAH4, and PAH8. Jiang et al. (2018) were reported in their study which was conducted in China that exposure to BaP, PAH4, PAH8, and Σ15PAH in grilled meat samples of the adult population was as 0.49, 3.96, 4.99, and 120 ng/kg bw/day, respectively. Researchers were stated that the dietary intake of PAHs is in relation to the dietary habits of the consumers and the contamination levels of PAHs in foods. Also it has been stated that the consumers would be exposed to more than average levels of PAHs as the consumption rate increases.

In this study, risk assessment of heat treated meat products was carried out with TEQ and MOE approach. The TEQ approach has been applied to directly assess the carcinogenity of PAH contamination to heat treated meat products (meat doner, chicken doner, meatballs, grilled chicken, and fish). BaP-like TEQs for individual PAH compounds were given in Table 4. In this study, the average TEQ value calculated for the Σ16PAH compound was 328.46, 570.9, 1,746.48, 310.46, and 1,116.42 ng/kg in heat treated meat doner, chicken doner, meatballs, grilled chicken, and fish samples, respectively. As a matter of fact, it has been reported that PAHs are formed in grilled meats cooked in charcoal fire depending on the amount of fat contained in the meat, the cooking temperature and duration (Lee et al., 2016).

In this study, the MOE value calculated for BaP and PAH4 was given in Table 5. The MOE value calculated for PAH4 in heat treated meat products was found as lowest at 165.048 in chicken doner samples and as highest at 425.000 in grilled fish samples. EFSA (2008) stated that if the MOE value was less than 10.000, it could be a potential concern for human health. Rozentale et al. (2018) stated that MOE was 11.602 for BaP and 8.486 for PAH4, which could be a risk for middle-aged consumers (39–50 years). A study by Duedahl-Olesen et al. (2015) in Denmark found a health concern with 7.080 and 8.450 of more value, respectively, with excessively contaminated barbecue and home cooked meat consumption on a daily basis in a worst-case scenario. Kim et al. (2014) found that MOE for PAH4 was 485.437 for fish and shellfish, 25.634 for meat and 265.957 for smoked products, and stated that the risk assessment results were at safe intervals. As a matter of fact, the data obtained in this study showed that the risk assessment results were within a reliable range.