1 Introduction

Meat and fish are essential sources of animal protein in high demand in Nigeria due to population growth and associated nutritional needs. They are highly perishable because of chemical and enzymatic reactions occurring during their various processing methods, such as cutting, storage, cooking, etc. [1]. Hence, it is important to preserve and process those using methods such as smoking to prolong their shelf-life and sustain their ever-increasing demand, or cook them (by grilling, barbecuing, etc.) to make them into dishes that are suitable and safe for human consumption [2].

Meat and fish smoking in Nigeria is mainly done by the traditional (direct) method involving heating the product over partially burning wood, which generates smoke that gives the meat a special taste and aroma [3]. Whereas, grilling is either done by direct method (charcoal or smoking wood in an open fire) or indirect method (an electric grill or grill pan) [4]. Many producers of these products in Federal Capital Territory (FCT), Abuja, Nigeria use direct methods, which are usually associated with poor process control like high temperatures above 400 ℃ and longer cooking and processing times, and these produce contaminants such as PAHs in the finished products [5, 6].

PAHs are a group of pollutants formed during the incomplete combustion of organic matter [7]. They occur in meat, fish, and their products as a result of various cooking and processing methods, especially smoking and grilling [8]. Food contamination by PAHs has drawn considerable attention globally because of its detrimental impact on human health and well-being as well as that of other creatures [9]. Those having two or three fused benzene rings are known as “low molecular weight’’ (LMW) PAHs, while those having four or more fused benzene rings like pyrene and benzo[a]pyrene are grouped as “high molecular weight’’ (HMW) PAHs [10]. HMW PAHs are more stable, more persistent, and more toxic than LMW ones [11]. Therefore, there are health concerns for regular consumers of grilled and/or smoked fish and meat due to possible dietary exposure to PAHs.

Many international organizations have classified them as very hazardous because of their potential to be mutagenic, carcinogenic, genotoxic, immunotoxic, teratogenic, and endocrine disruptors [12]. Also, eight of them (benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[ghi]perylene, indeno[1,2,3-cd]pyrene, and chrysene) are classified as genotoxic, whereas seven of these (excluding benzo[ghi]perylene) are categorized as carcinogenic. They are thus used to determine genotoxic and carcinogenic risks in humans [13]. In addition, the Panel on Contaminants in the Food Chain (the CONTAM panel) adopted PAH4 and PAH8 as better indicators of PAH occurrence and toxicity than only benzo[a]pyrene (B[a]P) [14]. Hence, maximum permitted levels of 0.002 and 0.012 mg/kg were respectively set for B[a]P and the sum of PAH4 (benzo[a]anthracene (B[a]A), chrysene (Chr), benzo[a]pyrene (B[a]P), and benzo(b)fluoranthene (B[b]F)) in traditionally smoked meat and meat products, as well as traditionally smoked fish and fishery products. While levels of 0.005 and 0.030 mg/kg were in turn given for B[a]P and PAH4 in heat-treated meat or fish and their products (including grilled meat or fish) [15]. Besides, continued data collection on PAHs in food was recommended by the Scientific Committee on Food (SCF) to assess food contamination and any potential changes in the PAH profile and levels [16].

Smoked and grilled meat and fish are widely consumed in FCT, and there is a lack of sufficient data on PAH profiles and levels in them. As a result, it is necessary to investigate these products, considering the risk of PAH exposure to human health. This study is therefore focused on assessing the profiles and levels of PAHs in smoked and grilled meat and fish consumed in FCT Abuja, to provide an updated report on them (based on SCF recommendations) [16], as well as the possible health hazards associated with regular consumption. The findings can help raise awareness among consumers and culinary professionals about the potential risks associated with high-temperature grilling and smoking. It may encourage the exploration of alternative cooking methods and techniques that can reduce the formation of harmful compounds like PAHs and also serve as a reference for future research on PAHs in heat-processed food.

2 Materials and methods

2.1 Materials

2.1.1 Chemicals and standards

A standard mix of sixteen United States Environmental Protection Agency (US EPA) priority PAHs in acetonitrile was obtained from Sigma-Aldrich, Bellefonte, PA, United States of America (USA) and used for analysis. They include Naphthalene (Naph), Acenaphthylene (Acy), Acenaphthene (Ace), Fluorene (Fluo), Phenanthrene (Phen), Anthracene (Anth), Pyrene (Pyr), Fluoranthene (Flt), Chrysene (Chr), Benzo[a]anthracene (B[a]A), Benzo[k]fluoranthene (B[k]F), Benzo[b]fluoranthene (B[b]F), Benzo[a]pyrene (B[a]P), Benzo[ghi]perylene (B[ghi]P), Dibenz[ah]anthracene (D[ah]A), and Indeno [1,2,3-cd]pyrene (I[cd]P).

Acetone (HPLC-grade) purity (99.99%) was acquired from Fischer Scientific, United Kingdom. Acetonitrile (HPLC-grade) (purity > 95%) was from Merck, Japan. n-hexane (98.0%), magnesium sulfate (MgSO4) (fine) (> 98%) for clean-up, and sodium chloride (NaCl) (99.5%) were obtained from Merck, Germany. MgSO4 anhydrous grit (coarse) was obtained from Sigma-Aldrich, USA, while disodium hydrogen citrate sesquihydrate (C6H6Na2O7∙1.5H2O) was purchased from Sigma-Aldrich, Germany. Trisodium citrate dehydrates (Na3C6H5O7∙2H2O) were from Sigma-Aldrich, Japan. Bondesil Primary Secondary Amine (PSA) sorbent was purchased from Agilent Technologies, USA, while C-18 sorbents were purchased from Supelco, USA.

2.2 Method

2.2.1 Sample collection and preparation

Smoked game meat, smoked fish (mackerel and catfish), grilled fish, and grilled chicken, as well as the uncooked samples, were purchased randomly from dealers in the various selling points in the Federal Capital Territory (FCT) (Kubwa, Dutse Alhaji, Jabi, the Central Area District, Garki II, and Gwagwalada). A total of 37 meat and fish samples were purchased from the vendors and supermarkets selling these products. The number of samples taken in each category are summarised in Table 1. The samples were then wrapped in aluminium foil, preserved separately to prevent cross-contamination, and kept in the freezer at 4 °C [17]. Before analysis, the preserved samples were shredded and further blended using a Waring 800 EG food blender to obtain a homogenized sample.

Table 1 Description of samples taken for PAHs analysis
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2.2.2 Extraction and clean-up

The Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) methodology, which is the European Standard EN 15662:2008 citrate buffered procedure [18], was utilized for sample extraction and clean-up. Approximately 5 g of sample and 10 mL of distilled water were added into a QuEChERS Teflon extraction/centrifuge tube and vortexed for 1 min. Next, 10 mL of HPLC-grade acetonitrile containing 100 µL (0.1 mL) of 0.5 µg/mL of surrogate standard Polychlorinated Biphenyl (PCB) 153 were added, shaken very well, and kept for 15 min. Then, 6.5 g of QuEChERS pre-mixed extraction salts (4 g of anhydrous magnesium sulfate (coarse), 1 g of sodium chloride, 0.5 g of disodium hydrogen citrate sesquihydrate, and 1 g of trisodium citrate dihydrate) were added, tubes caped, vigorously shaken for 1 min for quick distribution of the salt into the homogenized sample, vortexed for 3 min, and centrifuged for 5 min at 3000 rpm. A 6 mL aliquot of the upper organic phase was transferred into the QuEChERS 15 mL dispersive solid phase (dsp) clean-up Teflon centrifuge tube, comprising 1.2 g of the clean-up salts made up of 900 mg magnesium sulfate (fine), 150 mg primary secondary amine (PSA), and 150 mg C18 sorbents. The mixture was vortexed for 5 min and centrifuged as above. The upper layer was again transferred into a 10 mL graduated glass test tube with a cap, and 5% formic acid was added to it for stability (10 µL/mL of extract). The contents were shaken on a vortex shaker for one minute. Extract (1 mL) was transferred into a round bottom flask, evaporated at 40 °C to near dryness on a rotary evaporator, reconstituted in 1 mL of (4 + 1) hexane + acetone, and subsequently transferred to an autosampler amber vial ready for analysis by Gas Chromatography- Mass Spectrometry (GC–MS).

A Gas Chromatography GC-2010 Plus coupled to Mass Spectrometry (MS) QP2010 Ultra (Shimadzu, USA) fitted with a VF5 MS cross-linked capillary column of 30 m × 0.25 µm × 0.25 mm ID was used for analysis. Helium was used as the carrier gas at a constant flow rate of 1.2 mL/min. The purge flow was 3 mL/min with a linear velocity of 40 cm/s. The GC oven temperature was programmed from 60 °C/min (hold 1 min) to 200 °C at 10 °C/min (hold 2 min) to 300 °C at 10 °C/min (hold 3 min). The injection mode was splitless, with an injection temperature of 250 °C and an injection volume of 1μL. The ion source temperature of the MS was set to 200 °C, the interface temperature was 250 °C, and the solvent cut-off time was 3 min (solvent delay).

2.3 Validation of the method and quality control

The method's performance was checked using the US EPA’s SW-846, 8000D [19] guidelines. There were at least six calibration points, with values ranging from 0.05 to 2.0 µg/mL. The calibration curve's regression coefficients of determination (r2) were used to determine the linearity. The limit of detection (LOD) for each of the analytes was estimated using the standard deviation of ten replicate analyses of reagent (blank) water. Replicate analyses of at least one fortified sample matrix were performed at a fortification level of 0.5 µg/mL on each batch of 20 or fewer samples to assess recovery following the same steps used for the sample. The percentage recovery was determined using the ratio of the difference between the spiked and unspiked sample concentrations and the spiked sample concentration. Reagent blanks were analysed with each batch of samples for quality assurance and quality control.

2.4 Instrumental analysis, quantification and identification of PAHs

The standards and samples (1 µL) were injected into the GC–MS and run in Selected Ion Monitoring (SIM) mode in triplicate. For each target analyte, the characteristic primary ion was selected, along with additional qualifying ions for quantitation. The retention time and area of each observable PAH peak were measured for all analysed PAHs. Compounds were identified by comparing the retention times of the PAHs in the calibration standards with that obtained from the sample extracts. External standard calibration was used for quantification, which involved comparing the instrument (peak) responses from the sample to the target compound responses in the calibration standard using the six-point calibration curve. This was accomplished by plotting a calibration curve of analytes signal (SPAH) against analytes concentration CPAH in the calibration standard in μg/mL. The ratio of the detector response to the amount (concentration) of analytes in the calibration standard is defined as the calibration factor (slope (mL/μg)), which gives the sensitivity of the instrument response.

Furthermore, the analytes concentration in the extracts \({(C}_{ePAH}\)) (μg/mL) was given by the calibration Eq. 1:

$${C}_{ePAH} \left(\mu g/mL\right)=\frac{\left[{S}_{PAH}-a\right]}{b}$$
(1)

where b, is the slope of the calibration curve and a, is the y-intercept. This was derived from the linear equation of the calibration curve in Eq. 2:

$$Y =bc +a$$
(2)

Which is same as \(:{(S}_{PAH }=b{C}_{ePAH}+a)\)

The concentration of PAHs in the sample Cs (μg/g) was then calculated using Eq. 3:

$${C}_{S }= {C}_{ePAH} \times \left(\frac{{X}_{S}}{M}\right)$$
(3)

where, Xs = volume of extracting solvent (mL), M = sample weight (g) used for extraction, \({C}_{ePAH}\) = concentration of the analyte in the extract (μg/mL).

2.5 Statistical analysis

The analysis of PAHs was performed in triplicate (n = 3). The chromatograms and data obtained from GC–MS analysis were processed using the computer-based GC software GC–MS Solutions provided by Shimadzu Corporation. The results were then transferred to Microsoft Excel version 15.0 and SPSS Statistics version 25 for further analysis. Descriptive statistics were applied to the data, and individual PAH concentrations and the sum of PAHs are presented as mean ± standard deviations in the tables. Statistical tests of significance were performed at a p-value of 0.05. Pearson correlation coefficients (r) were performed to examine the association between PAH compounds in the different groups of meat and fish at p ≠ 0.

3 Results and discussion

The results of the method’s performance are presented in Table 2. The mean of individual PAH and the total PAH concentrations (mg/kg) in the grilled or smoked samples (including chicken, fish (mackerel and catfish), and game meat) as well as their raw counterparts are shown in Tables 3 and 4, respectively. Table 5 displays the correlation between various PAH levels in smoked or grilled meat and fish. Table 6 shows the Estimated Daily Intake (EDI) of PAHs in grilled and smoked meat/fish. Table 7 displays the Hazard Quotients (HQs) and Hazard Indices (HIs) of PAHs in the cooked samples. Table 8 presents the Margin of Exposure (MOE) of adults to PAHs in grilled and smoked meat/fish; and finally, Table 9 illustrates individual PAH carcinogenic potencies (B[a]Pteq) (mg/kg), toxic equivalents (TEQs) (mg/kg), etc. of PAHs in cooked samples.

Table 2 Retention time (RT), regression coefficient (R2), percent recovery (% R), precision as percent relative standard deviation (% RSD), and limit of detection (LOD) for the analysed PAHs
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Table 3 PAH concentrations (mg/kg) in the raw and grilled samples
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Table 4 PAH concentrations (mg/kg) in raw and smoked samples
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Table 5 Correlation coefficients between various PAH levels in smoked or grilled meat and fish samples
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Table 6 Toxicological parameters for risk assessment
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Table 7 Estimated daily intake (EDI) (mg/kg/day) of PAHs in grilled and smoked meat/fish
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Table 8 Hazard quotients (HQs) and hazard indices (HIs) of PAHs in grilled and smoked samples
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Table 9 The margin of exposure (MOE) of adults to PAHs in heat-treated meat and fish
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3.1 Method’s performance

The retention time, regression coefficient (r2), recovery percentage, relative standard deviation (RSD), and LOD for each PAH analysed are summarized in Table 1. The retention times of the analytes in the PAH standards served as a reference for the identification of each PAH in the sample extracts through comparison. Chromatograms of some PAH standards and two samples are shown in Figs. 1, 2, 3, 4. The regression coefficient (r2) was ≥ 0.995 for all analytes, implying the goodness of fit of the calibration curve to quantify PAHs. The relative standard error (%RSE) was ≤ 20% for all good-performing compounds and ≤ 30% for poor-performing compounds such as B[k]F, B[b]F, etc. Therefore, the linear regression model was adopted for quantification since it satisfies the US EPA acceptance criteria [19]. The LOD values (ranging from 0.024 to 0.060 mg/kg) were quite low. The mean percent recoveries ranged from 83 to 100% for all analytes (except I[cd]P), with %RSDs within 5.6–37.1%. These values were within the recommended range of 70–130% [19] and also showed that the method was effective in extracting and quantifying the PAHs in various samples. Similar values (74–117%) were reported by Al-Thaiban [20].

Fig. 1
figure 1

Chromatogram of PAH mix standard 1 (0.05 µg/mL)

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Fig. 2
figure 2

Chromatogram of PAH mix standard 6 (2.0 µg/mL)

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Fig. 3
figure 3

Chromatogram of smoked mackerel fish (SMF)

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Fig. 4
figure 4

Chromatogram of raw mackerel fish (RMF)

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3.2 The concentration of PAHs in the samples

The concentrations of PAHs were generally higher in cooked meat and fish than in their raw counterparts. Their presence in the raw samples may be ascribed to background contamination from anthropogenic activities in their natural environment via oral or dermal routes [21], while the low level may be attributed to reduced contamination levels, according to Urban and Lesueur [22]. PAH occurrence in raw mackerel fish and chicken have also been reported by [23, 24] respectively. The smoked samples showed higher values than the grilled ones. Across all sample groups, the concentrations of B[a]P were higher in the raw samples than in the cooked samples, implying that heat treatment may have decomposed the analytes, leading to a decrease in their concentration. The mean concentrations of individual PAHs vary based on meat or fish type and cooking method or technique.

Eleven individual PAHs were detected at various concentrations in the grilled samples (Table 4). Fish presented higher concentrations of PAHs than chickens. These variations may be attributed to differences in their composition [6], their origin or source [25], grilling techniques, and cooking duration, leading to either a decrease in concentration as per the decomposition of PAHs in the samples or an increase in PAH concentration as a result of the pyrolysis of organic matter. Some PAH compounds were not detected (ND) in any of the samples; for instance, acenaphthylene, fluorene, benzo[a]anthracene, benzo[b]fluoranthene, and dibenzo[a,h]anthracene. The non-detection of these compounds might be due to the low sensitivity of the analytical method used or the naturally low levels of these compounds in the food. In contrast, naphthalene and phenanthrene were two of the most frequently detected PAHs in the samples. Their presence in both raw and grilled samples suggests that they are naturally occurring compounds and not solely a result of the grilling process. Benzo[a]pyrene, a well-known carcinogen, was detected at a higher concentration in raw samples than in grilled samples, implying that grilling may have reduced the level.

Among the smoked samples, game meat showed the highest PAH16 concentrations (mg/kg), followed by catfish, while mackerel fish had the least (Table 5). High PAH16 concentrations among the samples and the observed variations could be the result of the smoking process or technique and the related factors such as the meat type or fatty acid composition and its transformation at high smoking temperatures, fat content, smoke content, level of exposure of edible parts of the meat or fish to smoke, temperature of combustion, and wood type [26, 27]. For instance, mackerel fish and game meat have been reported to contain high polyunsaturated fatty acid (PUFA) levels [28], which undergo chemical transformation at high temperatures to produce more PAHs. Moreover, PUFA levels correlate positively with PAH levels [29]. In addition, mackerel fish, being oily, may likely accumulate higher levels of heavier carcinogenic PAHs during smoking due to the melted fat's pyrolysis and high PUFA levels. These probably explain the very high total PAH16 in them. Game meat, too, has the highest concentrations of PAH4, PAH8, and CPAH.

The results also showed that all PAHs (apart from benzo[b]fluoranthene and dibenzo[a,h]anthracene) were detected in all smoked samples. Acenaphthene was the dominant PAH in smoked game and smoked mackerel, while naphthalene was dominant in smoked catfish. Benzo[a]anthracene (a potent PAH) was detected only in smoked game meat and mackerel fish. Furthermore, some PAHs showed higher concentrations in certain meats when smoked, while others had higher concentrations in raw samples. Naphthalene, a two-ringed PAH, showed increased concentrations in smoked game meat and catfish compared to their raw counterparts. In contrast, it showed a decrease in concentrations in the smoked mackerel fish (0.085 mg/kg) compared to the raw (0.142 mg/kg), and this may be attributed to thermal decomposition from longer cooking time as the fish sellers usually expose the fish to heat and smoke continuously until they are sold to prevent spoilage. This process may have also increased PAH concentrations in the fish depending on the smoking technique and the type of PAH; for instance, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, pyrene, and chrysene were detected at high concentrations in all the smoked samples, with acenaphthene being the most prominent. Fluoranthene was detected in both raw and smoked samples of mackerel fish and in the smoked samples of catfish and game meat. Benzo[a]pyrene showed higher values in the raw samples than in the smoked samples, suggesting that smoking may have reduced its concentration. Indeno[1,2,3-cd]pyrene was detected in raw and smoked catfish and in smoked mackerel fish and game meat. Benzo[b]fluoranthene and dibenzo[a,h]anthracene were not detected in any of the samples, raw or smoked, and this may be attributed to their absence or shallow levels in the analysed samples. Furthermore, the PAHs found in smoked fish in this study corresponded with the findings of refs. [26, 30,31,32,33] on PAHs in smoked fish.

3.3 Pearson correlation

Pearson correlation analysis among the samples revealed a strong positive correlation between PAH occurrence in grilled chicken and grilled fish, grilled fish and raw fish, grilled fish and raw game meat, and smoked mackerel fish, as well as smoked game meat. These results indicate a similar source or cooking process that leads to the concurrent formation of those PAHs in these samples. Results are shown in Table 5.

3.4 Human health risk assessment

The possible human health risks associated with exposure to PAHs in heat-processed meat and fish over time were estimated using the models proposed by regulatory authorities. It includes calculating the estimated daily intake (EDI) of PAHs in the samples and evaluating the non-carcinogenic risks as well as the carcinogenic risks [34, 35]. The toxicological parameters are listed in Table 6.

3.4.1 Estimated daily intake (EDI) of PAHs in the samples

The chronic (lifetime) human estimated daily intake (EDI) of PAHs in smoked and grilled samples was calculated using Eq. (4) [41].

$$EDI = \Sigma (Cn \times CR)/BW$$
(4)

where EDI = estimated daily intake; CR = the consumption rate for each meat or fish type; and Cn = PAH concentration, BW = Adult body weight (Table 6).

The individual PAH EDI values ranged from 10–8 to 10–5 (Table 7). The smoked fish samples (mackerel and catfish) tend to have higher EDI values for many PAHs compared to other samples, which may be attributed to their high consumption rate (0.0019 kg/AME/day) coupled with the high levels of PAHs found in them. The cumulative EDI values for PAH4, CPAH, PAH8, and PAH16 provide the combined intake of multiple PAHs, and higher values indicate higher cumulative potential risks. The smoked mackerel showed similar values to those reported by Bouka et al. [42]. Tongo et al. [33] also reported total EDI (ΣEDI) values ranging from 0.038 to 0.192 mg/kg/day in smoked fish samples, with smoked mackerel fish (Scromber Scromber) having the very high ΣEDI, just as reported in this study. Furthermore, individual EDI values were compared against the reference doses (RfD) and the cancer slope factors (CSF) for assessment of potential health risks. The values displayed in this study were all below the guidance values; hence, exposure has a lower potential risk.

3.4.2 Non-carcinogenic risks

Risks associated with dietary exposure to non-carcinogenic PAHs were estimated using the hazard quotient (HQ) and hazard index (HI) approaches [43, 44]. Hazard quotients are a measure of the potential risk associated with exposure to individual PAH compounds. They are calculated by comparing the exposure dose, or the estimated daily intake (EDI) dose, to the oral reference dose (RfD), as shown in Eq. (5). If the HQ is greater than 1, it suggests a potential risk of adverse effects. Hazard Indices provide an overall estimation of the cumulative risk associated with exposure to multiple PAHs. It is the sum of the HQ values for all PAH compounds being assessed in a sample, as illustrated in Eq. (6). An HI exceeding 1 suggests the potential for adverse effects from the combined exposure to multiple PAHs.

$$HQ =EDI/ RfD$$
(5)

where, HQ = hazard quotient, EDI = the estimated daily intake, RfD = reference dose. Pertinent RfD values (mg/kg/day) for identified PAHs are displayed in Table 7.

$$HI=\Sigma [HQ1+HQ2+HQn]$$
(6)

where HI = Hazard index.

The results in Table 8 gave insight into the possible non-carcinogenic risks associated with exposure to the PAHs in these samples using HQ and HI. There were differences in the estimated HQ values of the various grilled and smoked meats and fish. Values were generally low in grilled fish and grilled chicken and moderately high in smoked game meat, suggesting a relatively low potential risk for adverse health effects from consuming these foods. Notable values were reported for naphthalene, phenanthrene, pyrene, and benzo[ghi]perylene in grilled chicken; for acenaphthene, acenaphthylene, and phenanthrene in smoked game meat; as well as for acenaphthene, phenanthrene, and naphthalene in grilled fish. In mackerel fish, the HQ values for most PAHs were higher compared to other samples, indicating a higher potential risk. Whereas, in smoked catfish, the HQ values were notably high for naphthalene, phenanthrene, pyrene, and fluoranthene, also indicating a higher potential risk.

The order of the HI was: grilled fish; < grilled chicken; smoked game meat; < smoked mackerel; < and smoked catfish; < 1. These findings suggest that the non-carcinogenic risks associated with exposure to PAHs in grilled and smoked meat and fish vary across different types of meat and fish samples. Grilled fish appeared to have low potential cumulative risks, and grilled chicken and smoked game meat had a relatively higher cumulative risk. Smoked mackerel and smoked catfish showed elevated cumulative HI, indicating much higher potential health concerns due to combined exposure to multiple PAHs. Despite the estimated minimal danger of exposure (HI < 1) in all the samples, it is still important to avoid excessive consumption, as ingestion higher than what was reported may increase health risks.

3.4.3 Carcinogenic risks

The carcinogenic health risks associated with exposure to PAHs in grilled and smoked meat and fish were estimated by evaluating B[a]P and PAH4 (Chr, B[a]A, B[b]F, and B[a]P), carcinogenic PAHs (PAH7), PAH8), the margin of exposures (MOEs), the carcinogenic potencies of individual PAH concentrations (B[A]Pteq), carcinogenic toxic equivalents (TEQs), and the excess cancer risks (ECRs). All observed values were compared with regulatory limits to assess the potential health risks associated with the detected PAH levels. B[a]P and PAH4 are established indicators of PAH occurrence and toxicity in food based on the review by the Panel on Contaminants in the Food Chain (CONTAM Panel) [14]. They are classified as potentially carcinogenic and genotoxic to humans by organizations such as the International Agency for Research on Cancer [45]. Chronic oral exposure to high levels of these PAHs may increase the risk of developing certain types of cancer and other health issues [46]. Maximum limits of 0.005 mg/kg and 0.030 mg/kg for grilled meat/fish and their products, as well as 0.002 mg/kg and 0.012 mg/kg for smoked meat/fish and their products, are stipulated in the European Union (EU) Commission Regulation [15]. Concentrations above these limits suggest possible health concerns.

The sum of four carcinogenic PAHs (PAH4) was evaluated using Eq. (7):

$$PAH4= \Sigma (B[a]P+B[a]A+B[b]F+Chr)$$
(7)

The mean B[a]P concentrations and the PAH4 were above the EU limits in both the smoked and the grilled samples tested (Tables 3 and 4,), implying that regular consumption of these meats and fish may present health concerns. The markers of PAH levels reported in this study are in agreement with the reports of Mojiri et al. [25] and Akpambang et al. [47] on PAHs in smoked fish. Tareq et al. [37] also reported B[a]P and PAH4 levels higher than EU limits in grilled chicken and beef.

The benchmark doses and margin of exposure (MOE) characterization approach were used in the estimation of risks associated with exposure to carcinogenic and genotoxic PAHs (PAH8) [14]. The magnitude of the MOE is an indicator of the level of concern, but it is not a precise quantification of risk—the larger the MOE, the smaller the potential risk posed by exposure to the selected compound [48]. MOE values less than 10,000 indicate potential concern for human health. The MOE was calculated by dividing the toxicity estimate [benchmark dose lower confidence limit (BMDL10)] obtained from animal experiments by the estimated daily food intake using Eq. (8) [14].

$$MOE= BMDL10 /EDI$$
(8)

The values of BMDL10 are given in Table 6. MOE = margin of exposure; EDI = estimated daily intake.

All the samples show MOE values > 10,000 across various categories of PAH markers (Table 9), indicating a low risk of adverse health effects. The smoked fishes has the lowest MOE values for the PAH8, suggesting slightly higher potential risks compared to the other samples. MOE values obtained in this study agreed with the report in [8] on PAHs in smoked fish and smoked-dried fish and [27] on grilled fish. Although these results provide insights into the potential health risks, it is important to note that other factors, such as individual consumption patterns, overall diet, and other sources of exposure, could contribute to the health risks.

The carcinogenic potency of individual PAH (B[a]Pteq) was calculated via Eq. (9):

$$(B[a]Pteq) = Cn \cdot TEFn$$
(9)

where Cn is the concentration (mg/kg) of each congener n in the PAH mixture and TEFn is the toxicity equivalent factor for the specific congener n (an estimate of the relative toxicity of the individual PAH fraction compared to benzo[a]pyrene) [33]. The TEF values displayed in Table 10 were adapted from [49].

Table 10 Carcinogenic risk indices of PAHs in grilled and smoked meat/fish
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The values obtained ranged from 10–5 to 10–2 (Table 10). Benzo[a]pyrene had the highest value in all samples. In a report by Tongo et al. [33], the values for B[a]P in catfish were higher than in this study, while the value in smoked mackerel was lower than was reported here. The values for other PAHs were generally similar to those in this study. The carcinogenic toxic equivalents (TEQs) were further determined by the addition of the carcinogenic potency of individual PAHs (B[a]Pteq), as shown in Eq. (10) [11, 50].

$$TEQ= \Sigma B(\left[a\right]Pteq) =\Sigma (Cn.TEFn)$$
(10)

The TEQs (mg/kg) of PAHs in the samples showed that the carcinogenic potential of smoked mackerel fish was higher than in other samples, even when its total PAH concentration was lower than that of the smoked game meat (Table 10). This may be attributed to its high consumption rate. The values in this study were higher than those reported by Dokubo and Igwe [38] on PAHs in shellfish and Bouka et al. [42] on PAHs in smoked fish.

Compliance is determined by comparing the TEQ for each sample with the respective screening value (SV). The SV is the threshold concentration of chemicals in edible tissue that is of potential public health concern Tongo et al. [33] and it was calculated using Eq. (11):

$$SV = [(RL/CSF) \times BW] /CR$$
(11)

where, RL = maximum acceptable risk level, BW = Adult body weight (kg), CR = consumption rate for each product (Kg/AmE/day) (Table 6), CSF = slope factor for individual PAHs (mg/kg/day) (Table 7), TEQ values below their respective screening values (mg/kg) are an indication of low or no carcinogenic concern for humans through oral exposure. The screening values (SVs) of all PAHs in the samples were compared with the respective TEQ values, and results (Table 9) show that TEQ values (mg/kg) for grilled chicken (0.0543), grilled fish (0.0732), smoked game (0.0878), smoked mackerel (0.112), and smoked catfish (0.0927) were far below their respective screening values (mg/kg) of 108.55, 1085.48, 271.37, 57.13, and 57.13, an indication of low or no carcinogenic concern for humans through oral exposure. This report is consistent with that of [33] in a study of PAHs in smoked fish. However, they differed from those of [38] on PAHs in shellfish.

The TEQ is subsequently used to determine the excess cancer risk (ECR), which was evaluated via Eq. 12. When ECR is less than 10−6, cancer risk is considered negligible; it is tolerable when ECR is between 10−6 and 10−4, however, if ECR is greater than 10−4, cancer risk is unacceptable [35].

$$ECR = (Q \times TEQ \times CR \times ED \times EF)/(BW \times ATn)$$
(12)

where Q is the carcinogenic potency of B[a]P (7.3 mglkg/day), CR = consumption rate for each product (Kg/AmE/day), ED = Exposure duration (years), EF = Exposure frequency (days/year), BW = Adult body weight (kg), ATn = Average life span (days) (Table 6), TEQ is the calculated toxicity equivalent (Table 10).

The likely excess cancer risk (ECR) following lifetime dietary exposure to PAHs in meat and fish samples was compared to the acceptable guideline value of 10–6 set by the [35]. The values (between 10–7 and 10–5) obtained in this study were within the acceptable range (Table 10). Similar results have also been reported in other studies [33, 37].

4 Conclusion

Grilled and smoked meat and fish contain varying concentrations of PAHs with the highest total PAHs displayed in smoked game meat. They also contain different levels of potentially carcinogenic PAHs beyond the recommendations of the European Union. “Smoked mackerel fish” and “smoked catfish” appear to have the highest potential cancer risk among the samples studied. It is important to note from the results that regular consumption of these fish and also the game meat above the reported ingestion rate for a prolonged period may pose a possible human carcinogenic risk. These findings therefore underscore the importance of being mindful of cooking methods and techniques and their potential impact on chemical formation in food, as well as the need for dietary habits and choices that balance enjoyment and taste with health considerations. Future studies on the assessment of health risks from dietary exposure to PAHs should consider additional factors such as the duration and frequency of exposure, individual sensitivities, potential interactions between different PAHs, individual dietary habits, overall exposure to PAHs from other sources, and genetic disposition.