Microplastics and heavy metals in freshwater fish species in the southwestern region of Bangladesh:An emerging concern for public health

Microplastics(MPs)pollution and its associated toxicity raising concerns among scientists as a result of their toxicological impacts on human health and the ecosystem.This study aims to investigate the microplastics and heavy metals(HMs)contamination in seventeen freshwater fish species collected from the Southwestern region of Bangladesh.Microplastics extracted from these species using the hydrogen peroxide digestion method and characterized by Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy(ATR-FTIR).Atomic Absorption Spectrometry(AAS)was used to determine the concentration of HMs in different species for evaluating human health risks.A total of 142 microplastic particles were extracted with an average concentration of 1.13±0.84 items per individual of fish,where the highest microplastics were found in C.punctata(3.43±3.15 items)and lowest in A.mola(0.14±0.38 items).Identified microplastics were dominated by<1 mm size(87.3%),black color(60.6%),and fiber shape(94.4%).Polyethylene(73.08%),polypropylene(21.15%),and polystyrene(5.77%)were the most prevalent among the identified microplastic polymers.A positive correlation was found between microplastic numbers and fish weight and length.Low to moderate human health risks were associated with microplastics.The concentration(mg/kg)of heavy metals in studied fish samples was Cr(0.47 e2.89;0.79±0.56)>Cu(0.01e1.14;0.50±0.44)>Pb(0.04e0.58;0.22±0.12)>Cd(0.00e0.11;0.03±0.03),respectively.Heavy metals-based human health risk assessment results show that there are no major non-carcinogenic health risks(THI<1),while higher carcinogenic risks are present for consumers.

Assessment of heavy metal accumulation in freshwater fish of Dongting Lake,China:Effects of feeding habits,habitat preferences and body size

We measured the concentrations of Cr,Fe,Ni,Cu,Zn,Cd,Pb and Hg,and the stable isotope ratios(δ^(13)C and δ^(15)N)in 87 fish samples within 12 economic fish species collected from the Dongting Lake,the second largest freshwater lake in China.With few exceptions in concentration of Cr,most of fish species showed lower concentrations of the 8 metals than legislation thresholds.Piscivorous fishes had significantly higher values of δ^(15)N(possessing higher trophic level)and metal concentrations than planktivorous and herbivorous fishes.Moreover,demersal fishes showed higher concentrations of Cu,Zn,Cd and Pb than pelagic and benthopelagic fishes.We found positive correlations between concentrations of Fe,Pb and Hg and δ^(15)N ratio,confirming the biomagnification of the three metals through trophic transfer.In contrast,fishes showed clear growth dilution effect for Ni,Zn,Cu,Pb and Hg,indicated by the negative correlations between their concentrations and fish weight or length.Multiple regression analysis demonstrated that growth dilution and biomagnification effects simultaneously governed the metal concentrations in fish muscle,and the two effects'importance varied among different metals.The human health risk assessment indicated that all 8 metals gave target hazard quotient(THQ)values<1.0,i.e.,the estimated daily intake(EDI)of metals did not exceed the oral reference dose(Rf D),indicating a safe consumption of these fish species for consumer.Our study provides comprehensive approaches to better understand the determining processes and potential risk of heavy metals in freshwater lake fishes.