Introduction

The occurrence of pollutants and an increase in their concentrations in the environment, especially in the aquatic environment, are one of the greatest concerns (Heshmati et al. 2017, 2018; Rahmani et al. 2018; Rezaei et al. 2019; Shahsavani et al. 2017). Among the contaminations, potentially toxic elements (PTEs) have been specifically considered in various studies (Duruibe et al. 2007; Fakhri et al. 2017, 2018, 2019; Fathabad et al. 2018; Hadiani et al. 2015; Heshmati et al. 2018; Liu et al. 2019; Rahmani et al. 2018; Atamaleki et al. 2019).

The high levels of PTEs such as lead (Pb), cadmium (Cd), mercury (Hg), and nickel (Ni) among different types of fish resulted in some adverse effects on human health as well as environments (Adel et al. 2016; Dadar et al. 2017; Förstner and Wittmann 2012; Shahsavani et al. 2017). Generally speaking, the PTEs caused various adverse effects on the liver and kidney and resulted in lung disease, dysfunctions in the reproductive and cardiovascular systems, and nervous failure due to their mutagenesis, carcinogenesis, and teratogenesis effects (Dadar et al. 2016; Fakhri et al. 2017; Fathabad et al. 2018; Heshmati and Salaramoli 2015; Jaishankar et al. 2014). For instance, the high levels of Pb can result in intelligence quotient (IQ) reduction, anemia, and danger in hematopoietic, renal, reproductive, and central nervous systems (Assi et al. 2016), while in terms of Ni, some issues such as chronic bronchitis, cancer of the lung, decreased lung function, and nasal sinus can be expected (Zambelli and Ciurli 2013).

There is an increasing trend in global production of aquacultures during the last decade, and it is predicted that aquaculture will provide the most reliable supply of seafood in the future (Hixson 2014). Fish is one of the reliable sources of protein and essential metals, such as selenium and iodine, and vitamins including A, D, and E and B vitamin complex (Tacon and Metian 2013). Moreover, the digestibility of fish (89–96%) is higher than that of beef (87–90%) (Fallah et al. 2011b). Among different types of fish, the consumption of the rainbow trout due to high levels of omega-3 fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), with the tremendous impacts on the control of cardiovascular disease attracted notable attention (Steffens and Wirth 2005). However, the consumption of marine products particularly fish could offer some health benefits, and they can be considered as the potential source of food contamination such as PTEs, while the contamination of food products by PTEs can be correlated with some natural sources and anthropogenic processes including atmospheric deposition, geologic weathering, and agricultural activities (Ghasemidehkordi et al. 2018; Rajeshkumar et al. 2018). In terms of fish and related products, the concentration of PTE can be varied depending on the tissue types, the fish species, sampling site, pollutant type, trophic level, and mode of fish feeding (Weber et al. 2013).

Although some studies have been carried out regarding the contamination of PTEs among the farmed rainbow trout as one of the most consumed types of fish in Iran (Bubach et al. 2018; Dadar et al. 2016; Dizman et al. 2017; Fallah et al. 2011a; Tahsini et al. 2018; Varol et al. 2018; Varol and Sunbul 2017; Zamini et al. 2015), due to the variation in the reported concentration of PTEs, further assessments considering the levels of PTEs in rainbow trout farmed in different regions are crucial.

There is no published data on the PTE concentrations in farmed rainbow trout in Hamadan Province, Iran, as one of the most important centers for rainbow trout production. Therefore, the current research was conducted to determine the levels of Pb, Cd, Hg (elemental), Ni, Fe, Zn, and Cu in rainbow trout muscle, feed, and water samples collected from Hamadan Province. Also, the health risk of PTE for human and their bioconcentration factor (BCF) through water and feed were assessed.

Materials and methods

Chemicals

The standards for each PTE were obtained from Fluke (St. Louis, MO, USA). The nitric, perchloric, and sulfuric acids besides other chemicals all in the analytical grade were obtained from Merck (Darmstadt, Germany). Ultra-pure water was obtained by the Milli-Q water purifying system purchased from Millipore, Milford, MA, USA.

Sample collection

Rainbow trout (almost the same length and weight, n = 30), fish feed (n = 15), and water samples (n = 15) were collected from five fish farming centers located in Hamadan Province, Iran, during June–August of 2018 and were transferred to the laboratory under cool conditions (4 °C) (Fig. 1). The skin of the fish was removed, and the epaxial muscle located at the dorsal part of rainbow trout was cut, washed, and completely crushed with a meat grinder (Pars Khazar, Tehran, Iran) and packed in polyethylene bags to be stored at − 20 °C until analysis (maximum 2 months) (Heshmati et al. 2017).

Fig. 1
figure 1

The map of the study area

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Sample preparation

The chopped muscle and feed were dried in an oven at 100 °C for 3 h. Two grams of the dried sample was then weighed. For digestion, 20 mL of nitric acid (70%), 5 mL of sulfuric acid (96%), and 10 mL of perchloric acid (70%) were added (Sharafi et al. 2019). Afterward, the samples were placed on a heater for 30 min and heated until the solution volume reached 3 mL. The extract was passed through a filter paper (Whatman No. 2), to obtain a clear extract (Fathabad et al. 2018); then, its volume was reached 25 mL with the addition of ultra-pure water and placed in the refrigerator until analysis.

The determination of PTEs

The measurement of PTEs was carried out with the aid of inductively coupled plasma equipped with optical emission spectrometry (ICP-OES), manufactured by SPECTRO (Kleve, Germany). The PTEs such as Pb, Cd, Hg, Ni, Fe, Zn, and Cu were measured at wavelengths of 283.305 nm, 228.802 nm, 184.950 nm, 231.604 nm, 259.941 nm, 268.416 nm, and 324.754 nm, respectively. The ICP-OES conditions used for PTE analysis are shown in Table 1. For accuracy determination, each PTE was spiked at 3 levels in blank fish muscle, feed, and water samples. After sample preparation, PTE was measured according to the procedure described above. The concentration of each PTE was determined by ICP-OES divided by the spiked value and multiplied by 100 to obtain the recovery. Before the analysis of each PTE, calibration curves were illustrated, and limit of detection (LOD) and limit of quantification (LOQ) were determined as 3.3 SD/b and 10 SD/b, respectively, where SD is the standard deviation of analytical responses and b is the slope of calibration curve (Ullah et al. 2017). To check the precision and accuracy, the method of analysis was used using the international standard reference material (SRM 1648) (Motesaddi et al. 2018).

Table 1 ICP-OES operating conditions and measurement parameters
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Risk assessment of PTE intake through rainbow trout

For risk assessment, the target hazard quotient (THQ) and total target hazard quotient (TTHQ) were determined according to the following equation (Herrera-Herrera et al. 2018; Heshmati et al. 2017, 2018; Nabizadeh et al. 2018; Razzaghi et al. 2018):

$$ \mathrm{THQ}=\mathrm{EDI}/\mathrm{RfD} $$
(1)

where EDI (μg kg−1 dw day−1) is the estimated daily intake and RfD (μg kg−1 dw day−1) is a reference dose. The RfD accepted by the WHO and United States (US) Environmental Protection Agency for Pb, Cd, Hg, Ni, Fe, Zn, and Cu was 3.6, 1, 0.1, 20, 700, 300 and 40 μg kg−1 bw day−1 (EPA 2000; WHO 1993).

$$ \mathrm{EDI}=\mathrm{MC}/\left(\mathrm{dc}\times \mathrm{bw}\right) $$
(2)

where MC is mean concentration of each PTE (μg g−1), dc is the daily consumption of fish (kg day−1), and bw is the body weight of an adult (70 kg).

$$ \mathrm{Total}\ \mathrm{THQ}\ \left(\mathrm{TTHQ}\right)=\mathrm{THQ}\ \left(\mathrm{Pb}\right)+\mathrm{THQ}\ \left(\mathrm{Cd}\right)+\mathrm{THQ}\ \left(\mathrm{Hg}\right)+\mathrm{THQ}\ \left(\mathrm{Ni}\right)+\mathrm{THQ}\ \left(\mathrm{Fe}\right)+\mathrm{THQ}\ \left(\mathrm{Zn}\right)+\mathrm{THQ}\ \left(\mathrm{Cu}\right) $$
(3)

Daily consumption of fish was considered as 25.2 g day−1 (Heshmati et al. 2017).

In this study, for noncarcinogenic impacts of PTEs, CRlim, i.e., the maximum acceptable fish consumption amount for an adult person during 1 day (kg day−1), and CRmm, i.e., the maximum acceptable fish consumption amount (meals month−1), were calculated according to the following equations (Varol and Sunbul 2017):

$$ {\mathrm{CR}}_{\mathrm{lim}}=\left(\mathrm{RfD}\times \mathrm{BW}\right)/\mathrm{MC} $$
(4)
$$ {\mathrm{CR}}_{\mathrm{mm}}=\left({\mathrm{CR}}_{\mathrm{lim}}\times {T}_{\mathrm{ap}}\right)/\mathrm{MS} $$
(5)

where Tap is the mean period of a month (365.25 days/12 months = 30.44 days per month), MS is the size of a fish meal for an adult (0.227 kg), and BW is the body weight (70 kg) (Varol and Sunbul 2017). For all calculations related to risk assessment, the mean concentration of PTE of five farms was considered.

Biomagnification factor

Biomagnification factor (BMF) is the ratio of the concentration of a chemical compound in an organism to corresponded values in the diet (Mackay and Fraser 2000)

$$ \mathrm{BMF}={C}_{\mathrm{B}}/{C}_{\mathrm{A}} $$
(6)

where CB is the concentration of chemical, i.e., PTE in the organism (fish), and CA is the concentration of chemical, i.e., PTE in the related diet. The BMF is dimensionless.

Bioconcentration factor

Bioconcentration in fish implied the uptake of a chemical compound such as PTE through the water (Mackay and Fraser 2000). The BCF was obtained by the following equation:

$$ \mathrm{BCF}={C}_{\mathrm{B}}/{C}_{\mathrm{WT}}\ \mathrm{or}\ {C}_{\mathrm{B}}/{C}_{\mathrm{WD}} $$
(7)

where CB is the chemical concentration such as PTE (μg kg−1 wet weight) in fish, CWT is the total chemical concentration such as PTE in the water (μg L−1), and CWD is the freely dissolved chemical concentration in water. The utilization of CWD is preferred to CWT (Mackay and Fraser 2000). The BCF unit depended on the PTE units in fish and water.

Statistical analysis

SPSS software (version 16.0) is used to analyze the data. After measuring the amount of PTEs, their mean and standard deviation were calculated. The data were first tested for normality and homogeneity with the Kolmogorov–Smirnov test. Afterward, one-sample t test is used to compare the mean value with the permissible limits. The significant level in all statistical analyses was P < 0.05.

Result and discussion

The PTE concentrations in rainbow trout muscle

The defined parameters for method validation are presented in Table S1, demonstrating a good and precise established method for determination of the targeted PTEs among the collected samples. The PTE levels in rainbow trout muscle samples collected from 5 farms are shown in Table 2. However, the different concentrations of Pb, Cd, Hg, Ni, Fe, Zn, and Cu among the different samples were noted, and no significant differences were observed (P > 0.05).

Table 2 The concentration of the potentially toxic elements (PTEs) in farmed rainbow trout muscle (μg g−1 wet weight)
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In the current study, the highest (0.071 μg g−1 wet weight) and lowest (0.044 μg g−1 wet weight) concentrations of Pb were found in farm 4 and farm 2, respectively. The mean concentration of Pb in rainbow trout muscle of 5 farms was calculated as 0.056 ± 0.040 μg g−1 wet weight which was lower than that recommended level by the Food and Agriculture Organization (FAO) (1 μg g−1 wet weight) and EU (0.5 μg g−1 wet weight) (EC 2008; FAO 1983) while it was lower than those reported by Fallah et al. (2011a, b) in the Zayandeh-Rood River in Chaharmahal-va-Baghtiari Province, Iran (1.011 μg g−1 dry weight in farmed rainbow trout and 1.201 μg g−1 dry weight in wild rainbow trout); Tahsini et al. (2018) in farms located in Sanandaj City, Iran (23.65 μg g−1 wet weight); Dadar et al. (2016) in the Haraz River, Iran (0.25–0.57 μg g−1 dry weight); Ghomi (2016) in the Do Hezar River of Tonekabon, Iran (0.107 μg g−1 wet weight); and Zamini et al. (2015) in Gilan Province, Iran (0.252 μg g−1 dry weight, 0.294 μg g−1 dry weight, and 0.485 μg g−1 dry weight in Fouman, Talesh, and Siahkel farms, respectively). However, Pb level in the current study was higher than values reported by Varol and Sunbul (2017) in Keban Dam Reservoir, Turkey (54.21 μg kg−1 dry weight or 0.05421 μg g−1 dry weight in farmed rainbow trout and 51.5 μg kg−1 dry weight or 0.0515 μg g−1 dry weight in wild rainbow trout).

According to the findings, the mean of Cd in rainbow trout muscle was less than the detectable level by ICP-OES (0.313 μg kg−1 wet weight). In agreement with a previously conducted study in Beijing, China, the Cd level was lower than LOD (0.021 mg kg−1 wet weight) (Jiang et al. 2016). The concentration of Cd in the current investigation was lower than the results of other studies, 0.597 μg g−1 dry weight in farmed rainbow trout and 0.130 μg g−1 dry weight in wild rainbow trout by Fallah et al. (2011a) in Iran, 0.11 μg g−1 dry weight by Mendil et al. (2010) in Turkey, and 0.01 μg g−1 wet weight by Celik et al. (2008) in Turkey.

The highest and lowest levels of Hg were found in rainbow trout caught from farm 1 (0.003 μg g−1 wet weight) and farm 2 (0.08 μg g−1 wet weight), respectively. In a study conducted in Patagonia, Argentina (Bubach et al. 2018), the range of Hg (0.027–0.33 μg g−1 wet weight) was approximately wider than that of the current study (0.003–0.08 μg g−1 wet weight). All rainbow trout samples had Hg content lower than the allowable limit (0.5 μg g−1 wet weight). The average of Hg in this study (0.014 μg g−1 wet weight or 0.053 μg g−1 dry weight) was lower than that in findings reported by Fallah et al. (2011a, b) in Iran (0.314 μg g−1 dry weight in farmed rainbow trout and 0.292 μg g−1 dry weight in wild samples) and was higher than the Hg level in rainbow trout samples in China (0.005 μg g−1 wet weight) (Jiang et al. 2016).

According to EC, FAO, and WHO/FAO, the acceptable level of Ni for fish was 40 μg g−1, 55 μg g−1, and 300 μg g−1 (EC 2008; FAO 2000; WHO/FAO 2015). In this regard, the range (0.004–0.857 μg g−1 wet weight) and mean (0.14 μg g−1 wet weight or 0.546 μg g−1 dry weight) of Ni in trout samples were lower than mentioned legal limits and those in some previous studies (Mendil et al. 2010; Varol and Sunbul 2017; Zamini et al. 2015). However, the reported amounts of Ni by other authors were higher compared with those of the current investigation (Varol et al. 2018; Varol and Sunbul 2017).

Among the analyzed PTEs, Fe (1.051 ± 0.909 μg g−1 wet weight or 4.092 μg g−1 dry weight) had the most detected amount in rainbow trout muscle while the higher corresponded concentration was reported by Jiang et al. (2016) regarding the collected trout samples from China (6.964 μg g−1 wet weight), Mendil et al. (2010) from Turkey (8.425 μg g−1 dry weight), Varol and Sunbul (2017) from Turkey (7.14 μg g−1 wet weight), and Lourenço et al. (2012) from Portugal (4.5 μg g−1 wet weight). However, the results of the current investigation were similar to reported concentrations by Karatas (2014) in Turkey (3.65 ± 0.69 μg g−1 dry weight). The discrepancy in Fe content may be due to differences in the amount of this element in the feed ingested by fish.

The mean and range of Zn in the current study were 0.635 ± 0.725 μg g−1 wet weight and 0.043–4.102 μg g−1 wet weight, respectively. The Zn level of all rainbow trout samples was lower than the acceptable limit (30 μg g−1 wet weight). The mean of Zn in studies done by Lourenço et al. (2012), Varol and Sunbul (2017), Jiang et al. (2016), and Fallah et al. (2011a, b) was higher than that in the current study. However, Zn is an essential metal for hemoglobin synthesis and existed in the structure of several enzymes (Uauy et al. 1998). Zn also has an important role in metabolic pathways (Brown et al. 2001).

The mean of Cu in rainbow trout muscle was 0.275 ± 0.325 μg g−1 wet weight or 1.069 μg g−1 dry weight which was higher than that in the findings of Mendil et al. (2010) in Turkey (0.475 μg g−1 dry weight) and lower than that in rainbow trout studied by Karatas (2014) in Turkey (3.31 ± 0.66 μg g−1 dry weight) and Jiang et al. (2016) in China (0.348 μg g−1 wet weight). The difference between our results with other studies could be related to a variation in the levels of PTEs in the water and food resources of different regions as well as the weight of investigated fish.

The PTE concentrations in the feed

The levels of Pb, Cd, Hg, Ni, Fe, Zn, and Cu of feed consumed in 5 farms were different although no significant difference was noted (P > 0.05) (Table 3). The average level of Pb (0.047 ± 0.014 μg g−1 wet weight), Cd (0.322 ± 0.081 μg g−1 wet weight), and Hg (0.28 ± 0.071 μg g−1 wet weight) in the current investigation was lower than the permissible limit as 5 μg g−1 wet weight, 2 μg g−1 wet weight, and 0.5 μg g−1 wet weight, respectively (ISIRI 2014).

Table 3 The concentration of the potentially toxic elements (PTEs) in the feed of farmed rainbow trout (μg g−1 wet weight)
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According to previous studies, fish feed should contain Fe, Zn, and Cu in the levels higher than 30 μg g−1 wet weight, 30 μg g−1 wet weight, and 3 μg g−1 wet weight, respectively, to meet the fish’s needs (Fallah et al. 2011a). In our study, the mean Fe, Zn, and Cu levels were 79.544 ± 6.737 μg g−1 wet weight, 36.402 ± 4.076 μg g−1 wet weight, and 1.493 ± 0.416 μg g−1 wet weight, respectively. Therefore, it seemed that the Fe and Zn value is sufficient for fish although the Cu concentration of feed was less than the minimum amount of Cu recommended for fish feed (Fallah et al. 2011a). The levels of the whole PTE except Pb in feed were higher than those in rainbow trout muscle samples. In general, the PTE contents in feed followed the decreasing sequence Fe > Zn > Ni > Cu > Cd > Hg > Pb.

The content of Pb, Cd, Hg, and Cu in feed samples analyzed by Fallah et al. (2011a, b) was higher than that in the samples assessed in the present study. In contrast, the Fe, Ni, and Zn level in the current report was higher than that in the mentioned study (Fallah et al. 2011a). Compared to rainbow trout feed samples analyzed by Dadar et al. (2016), our samples contained higher levels of Ni, Zn, and Cu while their Pb and Cd contents were lower (Dadar et al. 2016). In addition, Jiang et al. (2016) found that the levels of Pb, Cd, Ni, Fe, Zn, and Cu in rainbow trout feed from Beijing, China, were 0.679 ± 0.481 μg g−1 wet weight, 0.718 ± 0.876 μg g−1 wet weight, 2.286 ± 1.597 μg g−1 wet weight, 544.0 ± 117.6 μg g−1 wet weight, 131.2 ± 49.50 μg g−1 wet weight, and 15.70 ± 2.559 μg g−1 wet weight, respectively, that all these were greater than our results although samples examined in the mentioned study had lower Hg (< 0005 μg g−1).

The PTE concentrations in water

The results of PTE levels in the water of farms are shown in Table 4. The concentration of all PTEs was lower than the allowable recommended limits for drinking water by US EPA (Martins et al. 2018; USEPA 2000). The concentration of Zn in the water (2.143–3.701 μg L−1) was higher than that of other PTEs, followed by Ni > Cu > Pb > Hg > Fe > Cd.

Table 4 The concentrations of potentially toxic elements (PTEs) in water samples (μg L−1)
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No significant differences among the concentrations of Pb, Cd, Hg, Ni, Fe, Zn, and Cu between water samples of 5 farms were noted (P < 0.05). The highest level of Pb in water samples was 0.204 μg L−1 which was collected from farm 4. The mean Pb level in water samples was 1.31 ± 0.66 μg L−1 that was lower than the permissible value (10 μg L−1) recommended by US EPA (USEPA 2000). In all farms, the concentration of Cd and Hg in water was lower than the detectable level. The average level of Ni in water samples was 2.11 ± 0.09 μg L−1 while the range of <LOD–3.29 μg L−1 was reported. The average Fe content in water samples was 0.24 ± 0.049 μg L−1. All of the water samples had Fe less than the acceptable limit (300 μg L−1) (FAO 2000; Martins et al. 2018). The Zn and Cu range in water samples was 2.143–3.701 μg L−1 and 1.537–1.748 μg L−1, respectively.

The levels of Zn, Cu, and Ni in water samples of five farms in the current study were higher than those reported for four farms of the Haraz River, Northern Iran, by Dadar et al. (2016) while the Pb and Cd content in the mentioned study was higher than that in the current study. Also, Fe, Cu, and Zn content in the water of the Fırtına River and Güneysu River in Turkey that was utilized for trout farming was higher than that in our finding although Pb in the water of farms assessed in the present was higher compared with the explored concentration by Dizman et al. (2017).

Health risk assessment of PTEs

The potential health risk related to PTE intake through rainbow trout consumption was demonstrated as EDI and THQ. The EDIs and THQ of each metal heavy are shown in Table 5. The EDI amount of Pb, Cd, Hg, Ni, Fe, Zn, and Cu was 0.020 μg kg−1 bw day−1, < 0.001 μg kg−1 bw day−1, 0.005 μg kg−1 bw day−1, 0.050 μg kg−1 bw day−1, 0.378 μg kg−1 bw day−1, 0.229 μg kg−1 bw day−1, and 0.099 μg kg−1 bw day−1, respectively.

Table 5 The estimated daily intakes of potentially toxic elements (PTEs) through farmed rainbow trout in Iran
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The THQ for all analyzed elements and the TTHQ amount were < 1; it means that there is no potential health risk to human. In previous studies, similar to our results, the amount of THQ for PTE intake through rainbow trout was reported as < 1 (Dadar et al. 2016; Jiang et al. 2016). The recommended daily intake (RDI) of Fe, Zn, and Cu for adults was considered as 18 mg day−1, 15 mg day−1, and 4 mg day−1, respectively. Therefore, rainbow trout consumption (25.2 g day−1) could provide 2.10%, 1.53% and 2.48% of RDI of these metals, respectively (Heshmati et al. 2017).

The results of the maximum permissible daily consumption content (CRlim) of rainbow trout muscle (Table 5) for analyzed metals were found to be high. Of seven PTEs, the lowest CRlim was related to Hg. Besides, CRmm values of farmed rainbow trout for all analyzed metals were > 67 meals month−1 (Table 5) that was higher than the value (16 meals month−1) suggested by US EPA (USEPA 2000). The CRmm value in our study for Pb, Ni, Fe, Zn, and Cu was higher than that in previous findings reported by Varol and Sunbul (2017).

Biomagnification factor and bioconcentration factor

The values of BMF and BFC regarding Pb, Cd, Hg, Ni, Fe, Zn, and Cu are shown in Table 6. In the current study, the mean BMF values of PTEs can be summarized as Pb > Cu > Ni > Hg > Zn > Fe > Cd while the rank order for BCF was Fe > Zn > Cu > Ni > Pb > Hg. The value of BCF which correlated with PTE is between 1000 and 5000, demonstrating that PTE has bioaccumulative property. If the BCF of PTE is less than 1000, that PTE is considered to be not bioaccumulative (Varol and Sunbul 2017). The value of BCF showed that the analyzed rainbow trout muscle could not be considered as bioaccumulative tissue for PTEs.

Table 6 Biomagnification factor (BMF) for intakes of metals through diet and bioconcentration factor (BCF) for intakes of metals through water in rainbow trout
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Conclusion

This study was conducted to investigate the levels of PTEs in farmed rainbow trout muscle, feed, and water samples collected from Hamadan Province, Iran, and also, the risk assessment of ingestion of these metals via consumption of this type of fish was assessed. Besides, the BMF and BCF for each PTE in rainbow trout muscle through feed and water samples were calculated. The results showed the mean and standard deviation of Pb, Cd, Hg, Ni, Fe, Zn, and Cu in rainbow trout muscle were 0.056 ± 0.040 μg g−1 wet weight, 0.313 μg g−1 wet weight, 0.014 ± 0.016 μg g−1 wet weight, 0.140 ± 0.188 μg g−1 wet weight, 1.051 ± 0.909 μg g−1 wet weight, 0.635 ± 0.725 μg g−1 wet weight, and 0.275 ± 0.325 μg g−1 wet weight, respectively, all of them were below the permitted limits. There was no significant difference between the amounts of PTEs in feed samples and also in water samples collected from five fish farming, and their PTE content was lower than the allowable limit. The risk assessment indicated the analyzed PTE intake through rainbow trout had no health risk to fish consumers. The BMF and BCF for all analyzed PTEs were lower than 1000. It showed the analyzed rainbow trout muscle could not be considered as a bioaccumulative tissue for PTE.