Benet-Risk Assessment of Fish And Shrimp Consumption From A Large Eutrophic Freshwater Lake, Southeastern China

Obtaining benecial nutrients meanwhile ingesting hazardous contaminants through freshwater sh consumption remains a concern for inland residents in China. In this study, contents of fatty acids, essential trace elements (Fe, I, Zn, Se, Cu, Mo, Cr) and non-essential trace elements (As, Cd, Hg, Ni, Pb) were quantied in nine sh and two shrimp species from large eutrophic Chaohu Lake, southeastern China. Benet-risk assessment for sh and shrimp consumption was conducted on basis of nutrients and contaminants. Total fat acids in the samples were 104.2-2405.2 mg/100g, included which DHA+EPA were 29.0-238.6 mg/100g. Mean content of essential trace elements (μg/g) in sh and shrimp species followed the order of Fe (10.3)>Cu (9.9)>Zn (7.7)> >Cr (1.42)>Se (0.337)>Mo (0.285)>I (0.023). The As, Cd, Hg, Ni, Pb content in the samples were nd-218, 14-97, 3-47, 4200-11300 and 144-1127 μg/kg, respectively, which was below the national maximum limit with the exception of Pb content in several samples. Though no obvious bioaccumulation pattern was found among species, species living in the demersal layers or with higher trophic levels tend to accumulate more trace elements. To achieve the recommended 250 mg of DHA+EPA daily intake, results of benet-risk assessment indicated that sh and shrimp consumption can be major source of Se, Cu, Mo and Cr intake, whereas sh consumption was potential non-carcinogenic risk exposure for Ni and microcystins. Benet-risk assessment contributed to the identication of main benets and hazards of freshwater sh and shrimp consumption for inland populations around the large eutrophic lake. auratus; MeA - Megalobrama amblycephala; CuA - Culter alburnus; HeM - Hemibarbus maculates; NeT - Neosalanx taihuensis; CoE - Coilia ectenes; PaM - Palaemon modestus; MaN - Macrobrachium nipponense. FAs - fatty acids; SFAs - saturated fatty acids; MUFAs - monounsaturated fatty acids; PUFAs - polyunsaturated fatty acids.


Introduction
Fish is an important dietary source of not only nutrient intake including protein and micronutrients but also contaminant exposure for humans (Geng et al., 2015). Particularly, sh is the main source of essential omega-3 polyunsaturated fatty acids, i.e. docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which is incorporated into membrane phospholipids that bene cial for human health including early cognitive and retinal development as well as cardiovascular diseases prevention (Sardenne et al., 2020). Trials have demonstrated that high content of DHA and EPA in marine oily sh could reduce blood triglycerides to protect cardiovascular function (Du et al., 2012). Daily intake 250-2000 mg of DHA + EPA has been recommended by World Health Organization (WHO) and several national health and nutrition organizations (Balshaw et al., 2012; Chinese Nutrition Society, 2016; EFSA, 2012). Besides, sh also contains trace elements such as selenium, molybdenum, and iodine, which are essential for the healthy function of human body (Du et al., 2012;Neff et al., 2014). Therefore, sh consumption included in a balanced diet is regularly recommended.
However, rapid urbanization and industrialization throughout the world have resulted in widespread water contamination, as a consequence of which sh is prone to accumulate toxic levels of environmental contaminants such as persistent organic pollutants (POPs) and heavy metals (HMs) that is detrimental to human health so as to decrease the health bene ts of unsaturated fatty acids and essential trace elements (Cui et al., 2018). For example,mercury, in particular the most toxic form methyl-Hg, is related to IQ loss or impaired neurodevelopment in vulnerable population including fetuses and offspring (Cardoso et al., 2018). However, the formation of inert Hg-Se complexes that diminishing MeHg accumulation could counteract the toxic effect of Hg, thus the Hg-Se molar ratio in sh has been proposed and widely used to evaluate Hg potential toxicity (Albuquerque et al., 2020;Grgec et al., 2020;Strandberg et al., 2016). Therefore, bene t-risk assessment should be performed with respect to the global increasing trend of sh consumption and widespread contaminants, consequently consumption of sh species those are high in fatty acids whereas low in environmental contaminants needs to be encouraged.
In recent years, a number of researchers have focused on the bene t-risk assessment of sh consumption for human health (Balshaw et al., 2012;Cui et al., 2018;Gladyshev et al., 2020). Various approaches, either deterministic or probabilistic, such as the bene t-risk quotient (BRQ) (Gladyshev et al., 2009), probabilistic exposure assessment based on the extreme value theory (Cardoso et (Du et al., 2012). Or equal amounts of marine sh and freshwater sh consumption is encouraged in healthy diet (Du et al., 2012;Geng et al., 2015). Freshwater sh, although contain lower DHA and EPA compared with marine sh, have much lower fat content that decreases the dietary intake of total fat to prevent cardiovascular diseases (Geng et al., 2015). Freshwater sh is frequently consumed in China (Jiang et al., 2018) and plays a signi cant role in the food systems of inland residents. However, rather limited investigations have been conducted on the bene t-risk assessment of freshwater sh consumption (Zhang et al., 2012a, b). Furthermore, more efforts have been made to characterize the bene cial effects of polyunsaturated fatty acids and Se (Grgec et al., 2020;Strandberg et al., 2016), whereas relatively less information on the other essential elements (e.g. Fe, I, Zn, Cu, Mo, Cr) in sh and shrimp, which can have detrimental effects on humans if consumed in excessive quantities, is present (Halder et al., 2020). Therefore, a full bene t-risk assessment on basis of fatty acids, trace elements, POPs, etc., should be performed with regard to freshwater sh consumption.
Chaohu Lake, ranking as the fth largest freshwater lake in China, is located in the middle of Anhui Province that surrounded by the capital Hefei City. It plays important roles in drinking water supply, shipping, shery, irrigation and ood control. However, due to rapid development of industrialization and urbanization in recent decades, large amounts of industrial wastewater and domestic sewage have been discharged into the lake that aggravating water quality deterioration (Liu et al., 2012a). The lake has been stressed by harmful contaminants such as POPs (Lyu et al., 2021;Tang et al., 2019;Wu et al., 2019) and heavy metals (Fang et al., 2017(Fang et al., , 2019aZhang et al., 2019). Potential threat has been posed on the ecosystems including biota and ora even the health of residents (Fang et al., 2017(Fang et al., , 2019a. The geographical position of Chaohu Lake, i.e. situated on the ood plain between the Yangtze River and the Huaihe River, made it representative to investigate the effects of water contamination on human health through consumption of aquatic species. To date, no bene t-risk analysis including the nutritional value in accompany with the non-carcinogenic and carcinogenic health effects through freshwater sh and shrimp consumption has been conducted for local residents. Therefore, the objective of the present study was to (1) quantify the fatty acids and trace elements in the main sh and shrimp species from Chaohu Lake, southeastern China; (2) conduct a bene t-risk assessment for consumers to ensure adequate essential intakes meanwhile minimizing non-essential exposure, basing on content of DHA + EPA, trace elements (essential and non-essential), and microcystins from previous related studies (Jiang et al., 2017). The overall health effects of sh and shrimp consumption could provide scienti c and practical consumption recommendation for general inland population in China, especially those residing in middle and lower reaches of the Yangtze River that relying heavily on freshwater sh as a subsistence food source.

Study site and sample collection
Lakes distributed in the Yangtze River basin have been burdened with rapid industrialization, urbanization and agricultural intensi cation in recent decades. Therein, Chaohu Lake, covering a surface area of ~ 760 km 2 with a mean depth of ca. 3 m, is one of the ve largest freshwater lakes meanwhile one of the three most polluted freshwater lakes in China, which is situated on the ood plain between the Yangtze River and the Huaihe River ( Fig. 1). Since the 1980s, the lake has suffered from serious pollution originating from industrial wastewater and domestic sewage (Liu et al., 2012a).

Sample preparation and analysis
Skinned dorsal muscle was dissected from large-sized individuals. Besides, small-sized sh such as ice sh and shrimp were homogenized as pooled samples respectively. Finally, a total of 125 individual and/or composite samples covering nine sh and two shrimp species were obtained for present study (Table S1). Water content was determined gravimetrically to convert concentrations from wet weight (ww) to dry weight (dw) when necessary. Approximately 2 g of wet weight sample were taken and dried to constant weight at 105°C in an oven.

Fatty acids analysis
Thirty-seven samples, including sh muscles and the whole bodies of small sh and shrimp species, were selected for fatty acids analysis, which was implemented using an acid hydrolysis method according to Chinese national standard (Determination of Fatty Acids in Foods, GB 5009.168-2016). Brie y, approximate 10.0 g of individual sample was weighed into 250 mL at-bottomed ask. Pyrogallic acid, zeolites, 95% ethyl alcohol and Milli-Q ultrapure water were added and mixed. The mixture was then hydrolyzed with hydrochloric acid and extracted with diethyl ether-petroleum ether mixture. Then, fatty acids methyl esters (FAMEs) were prepared under alkaline conditions. FAMEs were determined using a gas chromatography in a GC 2010 plus analyzer (Shimadzu, Japan). Analytical accuracy was checked by the internal standard (10-Hydroxy-2-Decenoic Acid, ANPEL Laboratory Technologies, Shanghai, China). Results were in the range of the certi ed values. Content of fatty acids were expressed in mg/100g of wet weight.

Trace elements analysis
Trace element analysis was conducted by means of wet digestion. Subsamples of 1.5-2 g (ww) were weighed and digested in a mixture of 5 mL concentrated nitric acid (GR, 65.0 ~ 68.0%) and 2 mL perchloric acid (GR, 70.0 ~ 72.0%) on a hot plate at a temperature range of 120-160°C. Digested solution was transferred to polypropylene tubes and diluted to 15 mL with ultrapure water. Concentrations of Hg, As, Se in the digested samples were determined by atomic uorescence spectrometer (AFS; AFS-230a) and Cr, Fe, Ni, Cu, Zn, Mo, Cd, I, Pb was quanti ed by inductively coupled plasma mass spectrometry (ICP-MS; Thermo Fisher Scienti c, X Series 2). Quality assurance and quality control (QA/QC) were applied throughout the analysis using reagent blanks, duplicates, and standard reference materials. Certi ed reference materials (GBW10018 and GBW10024) obtained from the National Center of Standard Materials of China was processed simultaneously during sample analysis. Rhenium was used as internal standard in ICP-MS determination. The determined results were in good accordance with the certi ed values and the recovery of metals was within the range of 80%-120%. Besides, the standard deviation of duplicate samples was within 10%. All contents were expressed in µg/g of wet weight except for As, Cd, Hg, Ni, Pb that was presented as µg/kg ww.

Data processing and analysis
Bene t-risk quotient (BRQ) was adopted to evaluate the bene t-risk effect of sh and shrimp consumption. The assessment was conducted on basis of the recommended daily intake of nutrients, reference dose, tolerable daily intake, and cancer slope factor of toxins. Non-carcinogenic and carcinogenic bene t-risk quotients were calculated according to Eqs. (1) and (2)  where R EFA (mg/d) was the recommended daily intake of essential fatty acids, i.e. DHA + EPA; c (mg/g) was the mean content of a certain contaminant in sh or shrimp species; C EFA (mg/g) was the mean content of DHA + EPA in sh or shrimp species; BW was the body weight, 60 kg for an adult; RfD was the reference dose (mg/kg/d), which was an estimate of daily exposure to human population that was likely to be without an appreciable risk of deleterious effects during a lifetime, US EPA; CSF was cancer slope factor; ARL was the maximum acceptable individual lifetime risk level, 1×10 − 6 . If BRQ < 1, to achieve the recommended daily intake of EPA + DHA, there was no obvious risk to human health through sh consumption, and vice versa (Gladyshev et al., 2009). Generally, 250 mg/d of DHA + EPA was su cient to prevent from coronary heart disease, thus this daily intake was adopted in present assessment (Cui et  The contribution of essential trace elements (ETEs) to recommended daily intake was calculated using the following Eq. where RDI ETE % was the contribution of essential trace elements to recommended daily intake from sh and shrimp consumption; c (mg/g), R FA (mg/d), C FA (mg/g) were the same as the aforementioned equations; RDI was the recommended daily intake amount (mg/d) of essential trace elements (WS/T 578.3-2017, China).
Data normality was veri ed by Kolmogorov-Smirnov test. Data was log-transformed before analysis as they were not normally distributed. Principle component analysis (PCA) was adopted to differentiate contents of trace elements in sh and shrimp species among various habitat and feeding habit.
Association between fatty acids and subgroups, effect of sh length and weight on trace element accumulation and correlation between trace elements were investigated by Spearman rank correlation analysis. Statistical tests were performed with IBM SPSS Statistics v.22 (IBM Corporation, Armonk, NY, USA). Signi cance was set as p < 0.05.

Content and composition of fatty acids
Total fat acids and subgroups including saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), omega-3 and omega-6 fatty acids in sh and shrimp species from Chaohu Lake were summarized in Table 1. Furthermore, the contribution of various subgroups to the total fatty acids and the mean percentage of DHA + EPA in omega-3 PUFAs for different species were depicted in Fig (Table 1), which was comparable to the ratios reported for sh species from Taihu Lake (0.8-1.2, Zhang et al., 2012a) and much lower than four as recommended by FAO/WHO (Zhang et al., 2012a). Therefore, in view of content and composition of fatty acids, sh and shrimp species from Chaohu Lake were considered healthy food choices for human consumption. were 29.0-238.6 mg/100g ww, covering a percentage of 5-31% in total fatty acids and 49-96% in omega-3 PUFAs (Fig. 2b), among which the highest mean value was found in shrimps Macrobrachium nipponense (185.3 mg/100g) and Palaemon modestus (184.3 mg/100g) whereas the highest percentage was discovered in ice sh (NeT), though total FAs for this boneless specie was least but it was abundant in calcium and protein that was much suitable for children. Therefore, greater nutritional values in abovementioned species enabled them to be identi ed as optimum choice for human consumption (Balshaw et al., 2012).
When setting those shrimp species aside, it could be found that greater content of omega-3 PUFAs was found in carnivorous topmouth culter (Table 1). It was speculated that feeding habits might be one of the main factors in uencing the fatty acid composition (Zhang et al., 2012b). Omnivorous and herbivorous sh were devoted to elongate and desaturate those algae or plants synthesized short chain fatty acids to long chain fatty acids. Further, carnivorous sh, which scavenged on other sh species with no need for chain elongation and desaturation, were typically rich in omega-3 PUFAs (Inhamuns and Franco, 2008). In eutrophic lakes, phytoplankton communities changed and decreased essential fatty acids that eventually affecting the composition of fatty acids in higher trophic level species (Jing et al., 2021;Sardenne et al., 2020). However, Laird et al. (2018) and Wang et al. (2020) deemed that phytoplankton contained high levels of omega-3 PUFAs therefore leading to greater omega-3 PUFAs in omnivorous and planktivorous sh, whereas Kainz et al. (2017) demonstrated that the contents of omega-3 PUFAs were related to total lipid in freshwater sh regardless of feeding sources and trophic positions. Therefore, the reason for discrepancy in fatty acid composition was disputed and needed further research.
The total fatty acids content in present study (1.04-24.05 mg/g) was within the reported ranges of previous studies (Table S2)

Content of essential and non-essential trace elements
Statistical description of essential and non-essential trace elements in the studied sh and shrimp species from Chaohu Lake were presented in Table 2. For essential trace elements, Fe was characteristic of the highest mean content being 10.3 µg/g, followed by Cu (9.9 µg/g), Zn (7.7 µg/g), Cr (1.42 µg/g), Se (0.337 µg/g), Mo (0.285 µg/g), I (0.023 µg/g). When in comparison with the maximum limits, it was found that Se content in more than half of the samples exceeded 0.3 µg/g (maximum tolerable level, Brazilian, Albuquerque et al., 2020) and Cr content in four samples was above 2 µg/g (GB 2762 − 2017, China). Indeed, the limit for Se was considered unrealistically low (Albuquerque et al., 2020). The nonessential As, Cd, Hg, Ni, Pb contents were in the range of nd-218, 14-97, 3-47, 4200-11300 and 144-1127 µg/kg, respectively, which was mostly below the maximum limits of the National Standard of China (GB 2762 − 2017) with the exception of Pb content in several samples. Overall, results revealed that nonessential trace elements were within a low content range in the majority of analyzed sh and shrimp samples from Chaohu Lake demonstrating a limited level of environmental exposure. In this case, trace element metabolism was considered to be regulated by homeostatic mechanisms, thus differences among sh species were related to physiological factors and feeding habits to a large extent (Albuquerque et al., 2020; Varol and Sünbül, 2018). Possible reasons for this discrepancy might be the limited sample size and relatively lower contamination level of trace elements in Chaohu Lake (Fang et al., 2017, 2019a, b). Accumulation of trace elements in sh was dependent on multiple factors including elemental type, trophic level, habitat, feeding habit, and ambient environment (Xia et al., 2019). Differences among sh species might be greater when sh was exposed to high environmental levels, which overloaded homeostatic mechanisms in sh (Albuquerque et al., 2020). Although no obvious bioaccumulation pattern was found among species, results of PCA analysis demonstrated that trace elements in sh and shrimp showed different accumulation tendency with various feeding habit and habitat (Fig. S1). It seemed that As, I, Cd, Zn, Pb, Se, Hg, and Cr was more accumulated in sh species living in the demersal layer or in sh species with higher trophic level, whereas the opposite trend was found for Cu, Mo, Fe, Ni. Therefore, non-essential elements in demersal or piscivorous species should be routinely monitored to ensure food safety.
Bioaccumulation of Hg in sh was closely related to the bioavailability of Hg (i.e. chemical speciation) in environment and the methylation e ciency of Hg to MeHg (Strandberg et al., 2016). Although Hg in water (Fang et al., 2019a) and sediment (He et al., 2016) was reported at levels of environmental concern in study region, Hg contents in sh and shrimp species from Chaohu Lake were much lower than the maximum limit of 500 µg/kg (GB 2762 − 2017, China) that suggested a low exposure across the aquatic ecosystem, which might be attributed to the low bioavailability of Hg in sediment (Fang et al., 2019a) and biodilution of cyanobacteria bloom (Strandberg et al., 2016). Mercury bioaccumulation in sh could be in uenced by the structure of the planktonic food web (Signa et al., 2019). In eutrophic lakes, Hg was diluted as higher algal biomass, and low content at the base of the food web led to lower content at higher trophic levels (Strandberg et al., 2016). Besides, fat deposition might also contribute to dilute Hg already present in sh tissues (Cressey et al., 2020). Nevertheless, Jing et al. (2021) found higher Hg content in planktivorous sh in a eutrophic reservoir, which was a consequence of trophic transfer, i.e., planktivorous sh were mainly fed on plankton whereas other species on arti cial sh food that experienced short time of Hg/MeHg exposure. Furthermore, sh and shrimp species from this study presented substantial Se content to countervail the toxic effects of Hg/MeHg exposure ( Table 2).
Broad comparison was carried out with reported data in worldwide studies (Tables S2). Content of trace elements in sh and shrimp species from Chaohu Lake were within the same order of magnitude as previously reported data. It was noteworthy that Zn content in present study was higher than those Signi cant positive correlations between total fatty acids and subgroups including SFAs, MUFAs, PUFAs, omega-3 and omega-6 fatty acids, and DHA + EPA were found (Table S3). In view of this, it was speculated sh increase or supplement fatty acids in equal proportions through food or other sources (Balshaw et al., 2012;Wang et al., 2020). The DHA + EPA were well correlated with total fatty acids (r = 0.711, p < 0.01), indicating that bene cial effects of sh consumption were closely associated with the fatness of sh (Neff et al., 2014;Strandberg et al., 2016). Furthermore, no signi cant correlation was found between the DHA + EPA contents in samples and habitats as well as feeding habits, which was consistent with previous study that PUFAs were adjusted as total lipid status regardless of feeding sources and trophic positions (Kainz et al., 2017). The relationship between sh length and fatty acids as well as subgroups was not investigated due to the composite samples of small-sized species included in FA analysis.
Correlation between fatty acids together with subgroups and trace elements were analyzed. Among trace elements, only Cu and As was positively correlated with fatty acids and subgroups, albeit the correlation was weak (r = 0.369-0.593, p < 0.05), indicating most of trace elements were lipophobic and more incorporated in proteins (Sobolev et al., 2019). Conversely, negative relationships were found between omega-3 fatty acids and Hg (p < 0.05), omega-6 fatty acids and Mo, Pb (p < 0.05), between DHA + EPA and Hg (p < 0.05). The negative correlation between fatty acids and Hg was sometimes discovered elsewhere (e.g. in Strandberg et al., 2016), indicating that the risk posed by toxic trace elements such as Hg could counteract the bene cial effects of essential fatty acids.
Accumulation levels tended to increase with sh size (Neff et al., 2014). Due to sample size, only Hypophthalmichthys molitrix (N = 56) and Aristichthys nobilis (N = 26) were chosen to investigate the effects of sh length and weight on bioaccumulation of trace elements at the species level. Results of Spearman rank correlation analysis were tabulated in Table S4. For Hypophthalmichthys molitrix, sh length and weight was signi cant factor for Fe, Cu, Mo, Hg, and Ni (p < 0.01), whereas for Aristichthys nobilis, it was positively associated with Cu (p < 0.01), Mo (p < 0.01), Cd (p < 0.05), Hg (p < 0.01), Pb (p < 0.05). Of note, Cu, Mo, and Hg were size-dependent in both species. Besides, negative association was found for As (p < 0.05) in ArN, indicating a dilution with growth and/or stronger detoxi cation and elimination mechanism of As in larger bighead shes. Difference in the correlation result was probably Spearman rank correlation analysis was applied to explore the relationship between various trace elements within each species (Table S5). For HyM, signi cant positive correlations were found between Fe, Cu, Mo and Ni (p < 0.01), whereas strong negative association were discovered including Se-As and Cr-As (p < 0.01). And for ArN, signi cant positive correlations were found between Fe, Cu, Mo, Ni and Pb (either p < 0.01 or p < 0.05), whereas strong negative association were recorded between Cu, Mo, Ni and As (either p < 0.01 or p < 0.05). Strong correlation among trace elements re ected either approximate contamination degree or analogous pollution sources (Sobolev et al., 2019). Iodine, Se, and Pb displayed no association with other trace elements for both species, representing their divergent originations or metabolism mechanisms. Selenium was commonly considered to play an important role in Hg cycling and methylation (Grgec et al., 2020), however, in present study, no signi cant correlation was discovered between Hg and Se whereas the correlation was found between Hg and Cu, Mo, demonstrating that other essential elements might have the potential to relieve Hg toxicity in aquatic ecosystem (Albuquerque et al., 2020).

Bene t-risk assessment
Fish consumption and the related bene cial and hazardous effects differed to a large extent in speci c areas, which was predominantly dependent on the composition of sh species and the amount of sh consumed (Du et al., 2012;Grgec et al., 2020). It should be kept in mind that the health bene t might be diminished by elevated content of environmental contaminants in aquatic species due to natural and anthropogenic activities that dispersing more contaminants into the aquatic ecosystems.
The bene cial effects of sh consumption were primarily ascribed to PUFAs, particularly DHA and EPA.
According to the amount of sh and shrimp consumed to obtain enough DHA + EPA, efforts were made to assess the potentiality of sh and shrimp consumption to ful ll the daily requirement of essential trace elements in human body (Halder et al., 2020; WS/T 578. . To achieve the recommended 250 mg of DHA + EPA daily intake, the daily sh consumption ought to be 134.9-355.1 g (CR EFA , Table 3).
Therefore, on basis of the aforementioned amount, the contribution of sh consumption to the recommended daily intake of essential trace elements, i.e. RDI%, was calculated and shown in Table 3. It was found that sh and shrimp consumption could contribute 66-392%, 164-366%, 31-98%, 580-1432% to the recommended daily intake of Se, Cu, Mo, Cr, respectively. Therefore, it could be stated that sh and shrimp consumption to be considerable source of Se, Cu, Mo, and Cr for consumers, which was different from previous study that sh consumption was of little importance in nutrients intake except DHA and EPA (Du et al., 2012). On the other hand, more attention was paid to Cr for its rather high RDI%. It should be noted that Cr content in majority of the samples did not exceed the maximum limit (GB 2762 − 2017, China) with the exception that four samples had Cr content greater than 2 µg/g. However, Cr commonly existed in the trivalent state in natural foods that was non-toxic to human health (Lescord et al., 2020). Otherwise, the non-carcinogenic health effects of Cr was calculated (Table 3) and results showed the BRQ NC for Cr was less than one signifying negligible health risk from Cr.  , 2020), thus the concern on the deleterious effects of As through shrimp consumption could be eliminated. Even so, the chemical speciation of As in shrimp species needed further investigation. Moreover, in eutrophic lakes, the potential health risk of hepatotoxic microcystins (MCs) should be raised attention in consideration to their potential liver damage in sh and humans (Jiang et al., 2017;Jing et al., 2021). Therefore, contents of MCs in aquatic species from previous study (Jiang et al., 2017) were obtained to investigate the non-carcinogenic effect as to achieve the recommended daily intake of DHA + EPA. It was of note that the non-carcinogenic effects of MCs deserved attention because the BRQ NC values for MCs was close to or higher than one (Table 4).
Management strategies should be taken to control the eutrophication in the lake to reduce the MCs accumulation in sh (Jing et al., 2021).

Uncertainty of the bene t-risk assessment
In this study, bene t-risk assessment was conducted on basis of the recommended daily intake of essential fatty acids (DHA + EPA) and trace elements (Fe, I, Zn, Se, Cu, Mo, Cr), reference dose of nonessential trace elements (As, Cd, Hg, Ni, Pb), tolerable daily intake of microcystins, and cancer slope factor of As. There were uncertainties related to the bene t-risk assessment: (1) The assessment assumed that inland residents obtained nutrients and contaminants through freshwater sh consumption, i.e. provided a fraction of food consumption, whereas excluding other dietary sources of nutrients and contaminants. Moreover, the assessment presumed that only one sh or shrimp specie was consumed in diet, yet the bene t and risk would be moderated by consumption of different species (Geng et al., 2015).
(2) For large-sized individuals, only dorsal muscles were investigated, however muscles from other portions (ventral, tail, etc) with different nutrients and contaminants were not included (Cui et al., 2018; Zhang et al., 2012b).
(3) Total content of trace elements were reported and evaluated, however, not all forms of trace elements were toxic to wildlife or humans (Lescord et al., 2020). For instance, arsenobetain and arsencholine were predominant organic-As compounds in freshwater sh (Gladyshev et al., 2020;Sobolev et al., 2019). And for Cr, the trivalent Cr was nutritionally bene cial while the hexavalent Cr was highly toxic and carcinogenic. Fortunately, Cr commonly existed in the trivalent state in natural foods (Lescord et al., 2020). Besides, cooking process might whether or not decrease the contaminant content in food. The bioaccessibility/bio-availability of nutrients and contaminants were not taken into account. Therefore, it was noteworthy that the risk of these elements to sh consumers might be over/under estimated.
(4) Besides non-essential trace elements, sh and shrimp were likely to accumulate other environmental contaminants that needed to be considered (Nostbakken et al., 2021). However, duo to the lack of corresponding RfD and CSF values, these contaminants were not included in present assessment.
(5) The average daily consumption of aquatic products for residents from the whole country, villages, cities and big cities were 29.6 g, 23.7 g, 44.9 g and 62.3 g, respectively (Zhai and Yang, 2006). Besides, it was regarded that a low sh intake of 15-35 g/d could have bene cial effect on heart disease and stroke (Du et al., 2012). However, the amount of sh consuming to ful ll the daily intake of essential fatty acids was 134.9-355.1 g/d, which was much higher than the statistical consuming amount, thus the practical ingestion of nutrients and contaminants might be much lower for inland residents through freshwater sh and shrimp consumption (Qin et al., 2020). Nevertheless, such integrated bene t-risk assessment was necessary to provide consumers with su cient information for healthy food choice (Gladyshev et al., 2009).

Conclusions
In present study, fatty acids, essential and non-essential trace elements were quanti ed in sh and shrimp species from large eutrophic Chaohu Lake, China. In view of the content and composition of fatty acids, sh and shrimp species were considered as healthy food choices for human consumption. Both essential and non-essential trace elements were reported within the same order of magnitude of worldwide range. Of the toxic elements, Pb seemed to be of concern for its exceeding beyond the national maximum limit in several samples. Habitat and feeding habits were probably attributed to the bioaccumulation of trace elements in studied species. According to the bene t-risk assessment, sh and shrimp consumption could be a major source of Se, Cu, Mo, and Cr to meet the daily requirement. Nevertheless, it could also be a potential non-carcinogenic exposure for Ni and microcystins that deserved attention. More exhaustive assessment was still needed for ensuring human health through freshwater sh consumption. Geographical location of Chaohu Lake and sampling area for present study.