INTRODUCTIONRainbow trout from North America is one of themost profitable members of the family in Turkishfreshwater farming. Black Sea trout, also known asTurkish salmon, has now taken its place on the Turkishfish market, following the decision of the GeneralDirectorate of Fisheries and Aquaculture of the Ministryof Agriculture and Forestry. Turkish salmon grows indam lakes until its weight reaches 180–220 g. After that,it is put into farms in the cold-water areas of the BlackSea. It is harvested when it weighs 3–4 kg.In 2019, fish farms produced 116 053 tons ofTurkish Salmon in inland waters and 9692 tons in seafarms [1]. This amount is constantly increasingcompared to previous years. Farmed trout from Turkey’ssouthern Black Sea littoral proved to be a rich nutritionalsource of fatty and amino acids, which normalizeatherogenicity and thrombogenicity indices of blood [2].Trout is mobile and prefers clean and oxygen-richwaters. As a result, even a slight contamination affectsthis fish, long before the water quality deteriorates.Even at low concentrations, metals in contaminatedfoods have harmful effects on human health [3]. Metalcontamination occurs in nature; nevertheless, humanactivities, such as mining and heavy industry, havesevere consequences for ecosystems and aquaticenvironment. Despite advancements in sewage effluenttechnology, sewage discharge remains a major challengein many developing countries [4].Metals have a strong impact on marine environmentand make their way into human food chains. Suchtoxicants as Hg, Cd, and Pb are associated with fishconsumption. Methyl Hg poisoning induced by prenatalingestion of contaminated fish causes infant mortalityand severe birth defects, such as mental retardation,cerebral palsy, and various neurological disorders [5–7].When Cd is deposited in the proximal tubular cellsof the kidney, it causes renal failure because ofthe decreasing glomerular filtration rates [8]. Pbpoisoning affects renal, hematological, cardiovascular,gastrointestinal, and reproductive systems. Moreover,skeletal abnormalities may occur as a result of renaldysfunction and Pb accumulation in the bones [9–11].Even though some metals are necessary, when their levelin the tissues exceeds a certain threshold, they damageboth individual organs and the entire organism.Fish, as an essential aquatic food in the human foodchain, has often been tested for metal contamination [3,12–14]. Several studies have identified metal residuesin various fish species, including trout. Rainbow trouthas also been subjected to toxicological studies, whichdetected accumulation in tissues and liver even at lowconcentrations of Zn [15].The current research dealt with both cancer andnon-cancer hazards associated with trace elements (Fe,Zn, Cu, Al, Pb, Hg, and Cd) in Turkish salmon. Despitethe fact that wellness threat assessment models werepredominantly created in Europe and the United States,the European model is still in development, getting evermore complex [16]. The American model, according toGržetić and Ghariani, is detailed and accurate [16]. Itis accessible through the Risk Assessment InformationSystem (RAIS), which is backed up by chemicalcharacteristic established and gathered by the U.S. EnvironmentalProtection Agency (U.S. EPA) IntegratedRisk Information System [17]. Following [18–22], thisresearch was based on the American model produced bythe U.S. EPA [23, 24].SRUDY OBJECTS AND METHODSTurkish salmon samples collection. The objectof the study was Turkish salmon collected from theYakakent farm between February and June 2019 (threeindividual samples per month). The samples wererandomly picked from fish offered for sale (Fig. 1).The samples were washed, stored in iceboxes, andtransported to the Hydrobiology Laboratory, theDepartment of Fisheries, to be tested for Fe, Zn, Cu, Al,Pb, Hg, and Cd. Prior to the analysis, the fish sampleswere documented for the required biological parameters,e.g. wet body weight and total length. The measurementswere based on the European Parliament’s Animal Careand Use Directive on the Protection of Animals Used forScientific Purposes [25]. After that, the samples werefilleted (Fig. 2), put into polyethylene bags, and storedat 21°C.Analytical procedures. The trace elementsin the Turkish salmon fillets were determined byinductively coupled plasma mass spectrometry(ICP-MS) after applying the pressure digestion methodat an environmental food analysis laboratory accreditedin Turkey (TÜRKAK Test TS EN ISO IEC 17025AB-0364-T). European Standard method EN 15763was used to determine trace elements using acid, wetdigestion, and standard reference material. The outputswere presented as mg/kg wet wt.Daily trace elements intake. Risk evaluations forinfants, children, and adults were conducted in orderto determine the potential hazards that may arise as aresult of consuming heavy metals with Turkish salmon.The risks were defined by calculating the probabilityof health hazard based on potential exposure. Therisk exposure depended on the daily consumption ofelements (mg/kg body weight per day). The estimateddaily intake (EDI) was calculated using element levelsand the amount of the fish consumed. The EDI of traceelements was calculated using the following equation:EDI =Cmetal (mgkg )X Wfish( kgday)BW (kg) ILCR = CDI × SF CDIcar. CDInon−car. =Cfish (mgkg )x EF (350 daysyear ) x ED (26 years) x FIR(41000 day ATa (365 daysyear x ED (26 years)) x BW (70 (1)where Cmetal is trace elements levels in the fillet;Wfish is the daily mean consumption of the fillet, whichwas reported as 0.041, 0.027, and 0.013 kg/day for adults,children, and infants, respectively [26]; and BW refers toan average adult’s body weight of 70 kg, a child’s weightof 30 kg, and an infant’s weight of 10 kg.Carcinogenic and non-carcinogenic risks. Theincremental lifetime cancer risk (ILCR) model wasused to predict the likelihood of cancer risks in the fishcaused by exposure to carcinogenic trace elements:ILCR = CDI × SF (2)where CDI stands for chronic daily consumption ofa carcinogen in mg/kg of body weight per day, andrefers the lifetime mean diurnal dose of exposure to thecarcinogen. The cancer risk connected with the exposureFigure 1 Turkish salmon Figure 2 Fillet of Turkish salmon319Bat L. et al. Foods and Raw Materials, 2021, vol. 9, no. 2, pp. 317–323to a carcinogenic or potentially carcinogenic materialwas calculated using slope factors (SF) [17].If the ILCR was < 10–6, it was regarded negligible; ifit was 10–6 < ILCR < 10–4, it was assessed as permissibleor tolerated; if the ILCR > 10–4, it was acknowledgedas substantial. The carcinogenic and non-carcinogenicCDI values were obtained using the followingformula [17]:Table 1 Trace elements content in the fillet of Turkish salmonMonthsContent, mg/kg wet wt.Fe Zn Cu Al Pb Hg CdFebruary 3.9a 2.2a 0.13a < 0.5a < 0.05a < 0.05a < 0.02aMarch 4.2a 2.3a 0.11a < 0.5a < 0.05a < 0.05a < 0.02aApril 4.8b 2.7b 0.23b < 0.5a < 0.05a < 0.05a < 0.02aMay 5.5c 2.6b 0.24b < 0.5a < 0.05a < 0.05a < 0.02aJune 6.7d 3.1c 0.33c < 0.5a < 0.05a < 0.05a < 0.02aMean ± SD 5.02 ± 1.12 2.58 ± 0.35 0.21 ± 0.08 < 0.5 < 0.05 < 0.05 < 0.02Letters a, b, c, and d show statistically significant differences (P < 0.05)Cmetal (mgkg )X Wfish( kgday)BW (kg) ILCR = CDI × SF CDIcar. =Cfish (mgkg )x EF (350 daysyear ) x ED (26 years) x FIR(41000 mgday )x 10−6 kg1 mgAT (365 daysyear x LT(70 years)) x BW (70 kg)=Cfish (mgkg )x EF (350 daysyear ) x ED (26 years) x FIR(41000 mgday )x 10−6 kg1 mgATa (365 daysyear x ED (26 years)) x BW (70 kg)THQ = CDIRf.D. HI= THQ (Fe) + THQ (Zn) + THQ (Cu) + THQ (Al) + THQ (Pb) + THQ EDI = (3)Cmetal (mgkg )X Wfish( kgday)BW (kg) ILCR = CDI × SF CDIcar. =Cfish (mgkg )x EF (350 daysyear ) x ED (26 years) x FIR(41000 mgday )x AT (365 daysyear x LT(70 years)) x BW (70 kg)CDInon−car. =Cfish (mgkg )x EF (350 daysyear ) x ED (26 years) x FIR(41000 mgday )x 10−6 kg1 mgATa (365 daysyear x ED (26 years)) x BW (70 kg)THQ = CDIRf.D. H I = T (H4)Q (Fe) + THQ where CDI – chronic daily intake of carcinogen;Cfish – trace element concentrations in the fillet;EF – exposure frequency; ED – exposure duration;FIR – fish ingestion rate for adults; AT – averagingexposure time for non-carcinogenic effects and 70 yearsof lifetime (LT) for carcinogenic effect; ATa – averagingexposure time for non-carcinogenic effects and 26 yearsof exposure for carcinogenic effect; BW – body weight.Many recent studies used the Target HazardQuotient (THQ) to peruse the potential non-carcinogeniceffect of elements in the edible tissues of fish. In thepresent study, THQ was computed using the followingequation to assess non-carcinogenic risks for traceelements in the fillet for adults [27–33]:ILCR = CDI × SF CDIcar. =Cfish (mgkg )x EF (350 daysyear ) x ED (26 years) x FIR(41000 mgday )x 10−6 kg1 mgAT (365 daysyear x LT(70 years)) x BW (70 kg)days) x ED (26 years) x FIR(41000 mgday )x 10−6 kg1 mgdaysx ED (26 years)) x BW (70 kg)THQ = CDIRf.D. H I = T H Q ( F e ) + ( 5T)HQ (Zn) + THQ (Cu) + THQ (Al) + THQ (Pb) + THQ (Hg) + THQ (Cd)where Rf. D. is an estimate of daily exposure that isunlikely to have significant adverse effects over thelifetime.The U.S. EPA oral reference doses for Fe, Zn, Cu,Al, and Cd are 0.7, 0.3, 0.04, 1, and 0.001 mg/kg/day,respectively [23, 24]. The Rf. D. value for Hg inorganicsalts is 0.0003 in the Risk Assessment InformationSystem (RAIS). However, there is no Rf. D. value forPb and its compounds [17]. The oral slope factor, on theother hand, is only indicated for Pb and its compoundsas 0.0085 mg/kg/day [17]. The Hazard Index (HI) wasfound by summing up the THQs, as illustrated by theequation below:HI= THQ (Fe) + THQ (Zn) + THQ (Cu) + THQ (Al) ++ THQ (Pb) + THQ (Hg) + THQ (Cd) (6)In the current study, the term “non-carcinogeniceffect” (HI) describes the cumulative non-carcinogeniceffect. If HI > 1.0, the CDI of a certain element exceedsRf. D, which indicates that the element poses a potentialrisk. Statistical analysis. The statistical analysis wasperformed using the statistical software SPSS Version21.0. The one-way analysis of variance (ANOVA)was used to examine the difference in trace elementquantities in the fish samples across months, followedby Duncan’s post hoc test. The threshold for significancewas set at P 0.05.RESULTS AND DISCUSSIONFifteen Turkish salmon were purchased for traceelement analysis. The fish had an average length of51 cm and a weight of 2.90 kg.Trace elements in the Turkish salmon. Theconcentrations of the trace elements observed in thesamples of Turkish salmon were generally low (Table 1).Fe appeared to be the most abundant element, followedby Zn and Cu. As long as they do not exceed certainconcentrations, such essential elements as Fe, Zn, andCu are not harmful to biota, including fish.No Al, Pb, Hg, and Cd concentrations weredetermined in the fillet samples. In both the EuropeanUnion Commission Regulation and Turkish Food Codex,the maximum allowable values of carcinogenic Pb, Hg,and Cd are 0.3, 0.5, and 0.05 mg/kg wet wt., respectively[34, 35]. However, neither the European UnionCommission Regulation nor the Turkish Food Codexgives any permissible values for Fe, Zn, Cu, andAl [34, 35]. These elements were far below the320Bat L. et al. Foods and Raw Materials, 2021, vol. 9, no. 2, pp. 317–323permissible values, namely Al ≤ 0.5, Cd ≤ 0.02, and Pband Hg ≤ 0.05.The sequence of trace elements according tocontamination was Fe > Zn > Cu > Al > Pb = Hg > Cd.The reason for the low amounts of Al, Pb, Hg, and Cdcould be that the fish farms are located in areas notcontaminated by urban or rural sewage. The toxicquantities of Fe, Zn, Cu, Al, Pb, Hg, and Cd in seafoodmay have a negative impact on consumers’ health.As a result, fish farms in coastal areas may be heavilycontaminated with non-carcinogenic and carcinogenichazardous materials that pose a substantial risk tohuman health. Thus, trace element levels in fish fromthis area should be regularly monitored and assessed.In fact, the toxic elements in fish depend on water,food, and sediment. However, accumulation of theseelements in food and water usually depends on otherfactors, e.g. metabolic rate, physiology, ecology,contamination tendency of food, sediment, and thetemperature, salinity, and solubility of water, as well ason the interaction of these parameters.In this study, food intake and uncontaminatedwater column had an important effect on the amount oftrace elements in Turkish salmon, which resulted in aconsiderable decrease in the toxic elements in question.As metabolic activity decreases with growth and aproportionally lower food intake, the accumulation ofelements decreases quite naturally. The trace elementsin Turkish salmon farmed in Yakakent appeared to bebelow the permissible thresholds set by internationaland national organizations, confirming the resultsobtained by other researchers who studied trace elementaccumulation in trout [31, 36].Estimated daily intake of trace elements. Table 2illustrates the EDI values of Turkish salmon farmed inthe Black Sea of Yakakent in 2019 for adults, children,and infants.The toxicity of trace elements in humans isdetermined by their daily intake. In Turkey, the averagefish consumption per adult is still low and remains at15–20 g/day, compared to the recommended amountof 41 g/day [1, 26]. However, people who live near thecoast consume far more fish than those who live incontinental Turkey. As a result, the research relied on thedata approved by the UN Scientific Committee on theEffects of Atomic Radiation [26]. The consumption ofthese contaminated fish parts puts the health of the localpopulation at risk.The EDI calculated for all chemical elements in thefish samples was compared with the toxicologicallyacceptable level and the oral reference dosage(Rf. D. values). The intake of all the trace elements wasbelow the Rf. D. limits. Thus, the trace elements inTurkish salmon pose no threat for the population of theregion.Human health risks. The Risk AssessmentInformation System classifies Cd, Hg, and Pb ascarcinogenic agents [17]. Chronic exposure to evenlow levels of Cd, Hg, and Pb could lead to a varietyof cancers. If it exceeds a certain threshold value, itcan have a carcinogenic effect. Table 3 demonstrates alifetime risk analysis for Turkish salmon consumers.Percent contribution to total risk by Fe, Cu, andZn was determined as 34.20, 24.80, and 41.01%,respectively. According to U.S. EPA, at ILCR 10–6,cancer threat is insignificant, the threshold risk limitof ILCR > 10–4 requires preventive medical measures,while ILCR > 10–3 signals that local public health isunder threat. In the present study, the samples of TurkishTable 2 Estimated daily intake (EDI) of trace elementsin Turkish salmon farmed in YakakentTraceelementsRf. D.ValuesEDI (2019) mg/day/ kg body wt.Infants Children AdultsFe 0.7 0.006526 0.004518 0.00294029Zn 0.3 0.003354 0.002322 0.00151114Cu 0.04 0.0002704 0.000187 0.00012183Al 1.00 – – –Pb – – – –Hg 0.0003 – – –Cd 0.001 – – –Table 3 Chronic Rf. D values, oral slope factor (SP), non-carcinogenic and carcinogenic chronic daily intake (CDI), target hazardquotient (THQ), hazard index (HI), and incremental lifetime cancer risk (ILCR) of trace elements in Turkish salmon in 2019Elements Chronic Rf. D.,mg/kg/dayOral slope factor (SF),mg/kg/dayNoncarcinogenic CDI,mg/kg/dayCarcinogenic CDI,mg/kg/dayTHQ ILCRFe 7.00E-01 – 2.82E-03 1.05E-03 4.03E-03Zn 3.00E-01 – 1.45E-03 5.38E-04 4.83E-03Cu 4.00E-02 – 1.17E-04 4.34E-05 2.92E-03Al 1.00E+00 – – – –Pb – 8.5E-03 – – – –Hg 3.00E-04 – – – –Cd 1.00E-03 – – – –HI = 1.18E-02 –321Bat L. et al. Foods and Raw Materials, 2021, vol. 9, no. 2, pp. 317–323salmon posed no cancer risk. Since none of the cancercausingtrace elements were detected, Turkish salmonconsumption can be considered beneficial. However, aregular control the contamination levels of farmed fish isessential.Chemicals can be either non-carcinogenic orcarcinogenic in health risk assessments. Noncarcinogenictrace elements have a threshold limit.Therefore, they are regarded as having no adverse healtheffects at doses below the threshold level computedusing the dose-response assessment method based on thespecific reference dose for each element. Carcinogenicsubstances, on the other hand, are believed to have noeffective threshold limits. This assumption impliesthat even low doses of the chemicals mean a low riskof cancer developing over time. As a result, there is nosuch thing as a safe level of exposure to carcinogenicsubstances [21]. In this sense, risk analysis and regularfollow-ups are essential for human health.The research also featured non-cancer risks of thetrace elements in Turkish salmon. The risk level ofhazard quotients (HQ) for adults was monitored for Fe,Zn, Cu, Al, Pb, Hg, and Cd. It revealed that consumingthese trace elements through a fish-based diet poseda significant non-cancer risk. Individual ingestionof these trace elements from Turkish salmon in thisregion, on the other hand, is safe (HQ < 1) for the localpopulation. Bat et al. and Yardim and Bat have obtainedsimilar results [31, 35]. The cumulative HI, which is thesum of individual trace element THQs, was also usedto describe the non-cancer hazards posed by Turkishsalmon. Since the total of hazard quotients was ≤ 1,Turkish salmon revealed no potential risk for humanhealth.CONCLUSIONThe hazard index was < 1, so the concentrationsof trace elements (Fe, Zn, Cu, Al, Pb, Hg, and Cd)proved to pose no health threat via consumption.Adults, children, and infants had the same riskranking, although infants were at a higher risk dueto their low body weight. However, since Turkishsalmon revealed no carcinogenic trace elements,and the non-carcinogenic trace elements werequite low, no consumer in any group is at risk.Risk within the non-carcinogenic trace elementsin Turkish salmon was as follows: Zn (41.01 %) >Fe (34.20 %) > Cu (24.80 %).Food safety requires an intensive study program andlongitudinal studies on the health risk of trace elementsin aquaculture products cultivated in Turkey’s coastalwaters, regardless of how safe the current results are.The practice of health management, according to Basseyet al., begins with routine monitoring by regulatorybodies, toxicologically assessment of wastewater usingconventional procedures, and raising public awareness ofhealth consequences [21].CONTRIBUTIONThe authors were equally involved in writing themanuscript and are equally responsible for plagiarism.CONFLICT OF INTERESTSThe authors declare no conflict of interests regardingthe publication of this article.ACKNOWLEDGEMENTSThe authors wish to acknowledge the Department ofHydrobiology, Fisheries Faculty, University of Sinop, forproviding laboratory facilities.