Health risk assessments of heavy metal exposure via consumption of marine mussels collected from anthropogenic sites

Assessment of cancer and dietary risks in commercially valuable marine organisms in coast of a region of future exploration (Equatorial South Atlantic)

The Equatorial South Atlantic region, spanning over 1700 km, is currently undergoing extensive exploitation through various activities such as oil extraction, desalination plants, marine mineral explorations, and wind power for green hydrogen production. This undoubtedly also contributes to the exacerbation of pre-existing chronic environmental impacts. This study aims to investigate the concentrations of 60 substances, categorized as Persistent Organic Pollutants (POPs) and Contaminants of Emerging Concern (CECs) from various classes including: polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs), as well as Pyrethroids (PPs), Triazines (TPs) and Organophosphates (OPPs) pesticides in consumable fish, shellfish, and crabs. The bivalve (Mytella charruana), crab (Ucides cordatus), and catfish (Sciades herzbergii) samples were collected in areas of ecological, environmental and economic importance. This data was used to estimate concentrations in the organisms, and to calculate cancer and human health risk. The most prevalent pollutant classes in the organisms were OCPs, followed by TPs and PPs. Shellfish and fish samples had more compounds indicating health risks, when compared to crabs. The substances causing cancer risks varied across organisms and study areas. The heightened cancer risks linked to specific compounds in various species highlight the urgent need to address persistent pollutants to prevent long-term health impacts on both humans and wildlife. Compounds such as PPs, TPs, and OPPs pose significant risks of neurotoxicity and endocrine disruption. This study underscores the interconnectedness of environmental and human health in coastal ecosystems, calling for continuous monitoring and adaptive management strategies to protect these fragile environments and the communities that rely on them.

Metal bioaccumulation in marine invertebrates and risk assessment in sediments from South African coastal harbours and natural rocky shores

Industrial and urban activities are major contributors to metal contamination in coastal systems, often impacting the physiology, distribution and diversity of marine invertebrates. This study assessed metal contaminations in sediments, seawater, algae and invertebrates across four armoured systems (harbours) and two natural sites along the south coast of South Africa. Bioaccumulation factors such as Biosediment (BSAF), Biowater (BWAF), Bioaccumulation (BAF) and bioremediation of metals by invertebrate bioindicators were also determined. Spatial variation in metal concentrations were observed, however, bioaccumulation of metals was site and species-specific. Invertebrates bioaccumulated higher metal concentrations in armoured than natural sites, with filter feeders exhibiting higher concentrations than grazers. Among filter feeders, Octomeris angulosa and Crassostrea gigas bioaccumulated elevated aluminium (Al), arsenic (As), chromium (Cr), zinc (Zn) and copper (Cu), while, Perna perna accumulated elevated nickel (Ni), cadmium (Cd) and lead (Pb). Among grazers, Siphonaria serrata and Scutellastra longicosta bioaccumulated elevated Al, Cr, Cd, cobalt (Co), Cu, Ni and Zn. Bioaccumulation factors indicated that (As, Ni, Zn) were bioaccumulated by algae, and invertebrates from sediment (BSAF>1) and from seawater (BWAF>1). Additionally, invertebrates bioaccumulated metals from their prey item, algae as indicated by (BAF>1). Arsenic Cd and Pb in invertebrates were above the maximum limit set for human consumption by various regulatory bodies. Our findings underscore the significant role of coastal invertebrates in bioaccumulating and bioremediating metals, suggesting a natural mechanism for water quality enhancement, especially in urbanised coastal areas.

Seasonal Monitoring of Heavy Metal Pollution in Water and Zebra Mussels Dreissena polymorpha as a Potential Bioindicator Species from Lake Habitat

In aquatic ecosystem, metal pollution is an important environmental hazard. Mussels as a bioindicator species are often used for assessment the presence of potentially toxic metals. Hence, the present study aimed to assess the effect of seasonal variations on some heavy metals (Cd, Cr, Pb, As, Zn and Cu) accumulation in water and Dreissena polymorpha from lake habitat. Our result indicated that Zn accumulated at a very high level in the zebra mussels while As accumulated at a high level in water samples. Seasonal variations significantly affected Cu concentration in the water samples (P < 0.05) while Cr concentration in the mussel samples was significantly affected by seasonal variations (P < 0.05). According to the water analysis, mean concentrations of metals are below the maximum limits established by the World Health Organization and USEPA, except As. Overall, our data emphasize anthropogenic pollution in the Turkish aquatic environment and confirm the use of D. polymorpha as a prospective biomonitor for metal polluted sites'.

Size-dominated biotoxicity of microplastics laden with benzophenone-3 and ciprofloxacin: Enhanced integrated biomarker evaluation on mussels

Microplastics (MPs) are emerging pollutants with diverse sizes in aquatic environments. This paper investigates the toxicity of micron- and nano-scale polystyrene (50 μm, 5 μm, 0.5 μm) loaded with 2-hydroxy-4-methoxy-benzophenone (BP-3) and ciprofloxacin (CIP) by eight biomarker responses in mussels, perna viridis. The mussels were exposed to MPs and chemicals for 7 days before 7 days of depuration. Eight biomarkers were measured to determine biotoxicity over time by using the weighted integrated biomarkers index evaluation (EIBR). Mussels exposed to MPs on a daily basis demonstrated a cumulative toxic effect. The toxicity of MPs for mussels was inversely related to the size at which they can be ingested. Then toxicity was reversed when exposure was halted. EIBR mold has shown a significant difference in the biotoxicity of each biological level under different exposure scenarios. In general, the mussel toxicity influenced by BP-3 and CIP exposure without an adsorbent was insignificant. MPs laden with them increased the toxicity of mussels. Under condition of lower concentration of ECs (Emerging contaminants), the presence of MPs as a component of a combined pollutant in water dominated the biotoxicity for mussels. The EIBR assessment further validated that the biotoxicity of mussels was size-dependent. Its application simplified the biomarkers' response index and enhanced the accuracy of evaluation by weighing on molecular, cellular and physiological level. Specifically, mussels were physiologically sensitive to nano-scale plastics, with nano-scale plastics causing a higher level of cellular immunity destruction and genotoxicity than micron-scale plastics. Enzymatic antioxidant systemswere upregulated based on size-differential plastics; however, the total antioxidant effect of non-enzymatic defenses appeared to be least affected by the size effect.

Evaluation of metal pollution related to human health risk in freshwater snail Viviparus contectus (Millet, 1813) as a potential bioindicator species in Lake Habitat (Turkey)

Freshwater mollusks are employed as bioindicators for the assessment of water quality in biomonitoring studies since the water quality of natural resources is crucial for humans. The freshwater snail species known as Viviparus contectus (Viviparidae: Gastropoda) is one that people eat. Here, the levels of heavy metals (Cd, Cr, Pb, As, Zn, and Cu) in water and V. contectus samples were determined. An Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES, Spectro Arcos, vertical plasma) was used for the analysing the heavy metal concentrations in water and freshwater snail samples. The results of the current investigation demonstrated that freshwater snails accumulated metals in their water and soft tissues in the following orders: Pb > Cr = Zn = Cu = Cd = As and Zn > Cu > Pb > Cd > As = Cr. Autumn was the time of year when higher amounts of heavy metals (As, Cr, Cu, Zn, and Hg) were found. Pb content in the freshwater snail samples was strongly impacted by seasonal fluctuations (P 0.05). For adults, the EDI (estimated daily intake) values were lower than the TDI (tolerable daily intake) values, and the HI (hazard index) values were below 1. Freshwater snail samples had Zn and Pb levels that were over the FAO/WHO, Turkish Food Codex, JECFA, and EC limit values. Except for Pb, the water study shows mean metal concentrations below the USEPA, Turkish Pollution Control Regulation, and World Health Organisation maximum allowed levels. Aquatic ecosystems were negatively impacted by anthropogenic activities overall, and this study can provide a helpful data set for investigations on metallic contamination in water bodies and biomonitoring in freshwater ecosystems.

Lower Health Risks of Potentially Toxic Metals after Transplantation of Aquacultural Farmed Mussels from a Polluted Site to Unpolluted Sites: A Biomonitoring Study in the Straits of Johore

The present field-based study aimed to determine the levels of six potentially toxic metals (PTM)s (Cd, Cu, Fe, Ni, Pb, and Zn determined using a flame atomic-absorption spectrophotometer) using transplanted green-lipped mussel Perna viridis from a polluted site at Kampung Pasir Puteh (KPP) to unpolluted sites at Kampung Sungai Melayu (KSM) and Sungai Belungkor (SB) in the Johore Straits (SOJ), and to estimate the human health risks of the PTMs after the depuration periods. Interestingly, after 10 weeks of depuration in the two unpolluted sites, there were 55.6-88.4% and 51.3-91.7% reductions of the six PTMs after transplantation from KPP to SB and KSM, respectively. Lower risks of health assessments were recorded and judged on the present findings of significantly (p < 0.05) lower levels of safety guidelines, significantly (p < 0.05) lower values of target hazard quotient, and significantly (p < 0.05) lower values of estimated weekly intake, of all the six PTMs after 10 weeks of depuration of the transplanted polluted mussels to the two unpolluted sites in the SOJ. Thus, further reducing the noncarcinogenic risks of the PTMs to the consumers. From an aquacultural point of view, this depuration technique can be recommended to reduce the health risks of PTMs to mussel consumers.

Potential risks of heavy metals in green mussels (Perna viridis) harvested from Cilincing and Kamal Muara, Jakarta Bay, Indonesia to human health

This study investigates Pb, Cd, and Cr in the suspended particulate matter (SPM), sediments, and green mussels from Cilincing and Kamal Muara, Jakarta Bay and estimates their potential human health risks. The results showed that the metal levels in SPM from Cilincing ranged from 0.81 to 1.69 mg/kg for Pb and 2.14 to 5.31 mg/kg for Cr, while in Kamal Muara ranged from 0.70 to 3.82 mg/kg for Pb and 1.88 to 4.78 mg/kg dry weight for Cr. The levels of Pb, Cd, and Cr in sediments from Cilincing ranged from 16.53 to 32.51 mg/kg, 0.91 to 2.52 mg/kg; and 0.62 to 1.0 mg/kg whereas in Kamal Muara ranged from 8.74 to 8.81 mg/kg; 0.51 to 1.79 mg/kg, and 0.27 to 0.31 mg/kg dry weight, respectively. The levels of Cd and Cr of green mussels in Cilincing ranged from 0.014 to 0.75 mg/kg and 0.003 to 0.11 mg/kg; while in Kamal Muara ranged from 0.015 to 0.073 mg/kg and 0.01 to 0.04 mg/kg wet weight, respectively. Pb was not detected in all samples of green mussels. The Pb, Cd, and Cr levels in the green mussels were still below the permissible limits set by international standards. However, the Target Hazard Quotient (THQ) for adult and children in several samples were higher than one indicating potential noncarcinogenic effects to consumers due to Cd accumulation. To reduce the detrimental effects of metals, we suggest maximum mussel consumption of 0.65 kg for adults and 0.19 kg for children in a week based on the highest level of metals.

Bioaccumulation of potentially toxic elements in fish species of Serbia: a review

In the first review of potentially toxic elements (PTEs) in fish in water ecosystems in Serbia, 40 studies related to fish contamination with PTEs were identified and evaluated. Studies of concentrations of PTEs in fish tissues covered 28 ecosystems (108 localities). The main studied river ecosystems were the Danube and the Sava, and the Međuvršje reservoir was the most studied standing water ecosystem. Among the most studied fish species were catfish (Silurus glanis), followed by pikeperch (Sander lucioperca), bream (Abramis brama), carp (Cyprinus carpio), and barbel (Barbus barbus). There were 48 "hot spot" sampling sites where concentrations of Hg, Cd, Pb, As, Ni, Fe, and/or Cu exceeded the maximum permitted concentrations (MPCs) prescribed by legislation. Elevated concentrations of these elements were the most detected in fish species sampled in the Danube, Sava, and rivers belonging to the Velika Morava basin. Hg concentrations were the most common above MPC in muscle tissue of species sampled from the Danube and Sava rivers. On the other hand, we can single out the species Vimba bream (Vimba vimba), sampled in Danube River in Zemun near Belgrade, as the safest species for human consumption due to the largest number of elements in fish meat below detection limits. Finally, having in mind all the criteria prescribed by U.S. EPA (2000), we identify and recommend two predatory fish species pikeperch (S. lucioperca) and catfish (S. glanis), and bottom-feeding fish species barbel (B. barbus) as bioindicators of PTEs contamination in Serbian waters.

Content of Trace Elements and Human Health Risk Assessment via Consumption of Commercially Important Fishes from Montenegrin Coast

Muscle tissues of Mullus barbatus and Merluccius merluccius were analyzed for the presence of selected trace elements (As, Hg, Cd, and Pb) to determine the value of the daily intake of trace elements from fish consumption and to assess the risk to human health. The mean concentrations of As in the muscle tissue of M. barbatus and M. merluccius for the entire period were 19.689 mg/kg wet weight (ww) and 8.356 mg/kg ww, Hg 0.497 mg/kg ww and 0.153 mg/kg ww, and Pb 0.031 mg/kg ww and 0.025 mg/kg ww, respectively. The concentrations of Cd in all fish sampled were below the detection limit (<0.02 mg/kg ww). The evaluation of the potential health risk assessments based on the target hazard quotient (THQ) and estimated daily intake (EDI) indicated that the intake of As in both fish species and Hg for M. barbatus could pose an appreciable risk to human health. The calculated hazard index (HI) was higher than 1 for both fish species. The continuous monitoring of trace elements' concentrations in fish is strongly recommended, as the results demonstrate potential health risks due to the presence of As and Hg.

Metals and co-presence of other pollutants in mussels (Perna perna) around Algoa Bay: Human consumption safety concerns

Elevated metal concentrations can become harmful to marine organisms and to humans that consume them. Metal concentrations at multiple sites around Algoa Bay, South Africa, were last investigated in the 1980s. We collected wild brown mussels (Perna perna) from seven sites around Algoa Bay, and quantified metallic elements using ICPMS. Metallic element concentrations differed significantly among the sampling sites and correlated with pollution sources at specific sites. The concentration of Pb in mussels at one site slightly exceeded South African limits. Based on the South African estimated daily intake, the target hazard quotient, and South African metal limits, mussels from Algoa Bay are safe for human consumption, except possibly from one site. However, combined with data on bisphenols and benzophenone UV filters in P. perna from the same sites, we suggest a possible health concern to consumers.

Temperature, salinity and body-size influences depuration of heavy metals in commercially important edible bivalve molluscs of India

The effect of temperature, salinity and body-size on depuration of naturally accumulated heavy metals in clams, mussels and oysters harvested from Ashtamudi and Vembanad estuaries of Kerala, India were investigated using a static depuration system. Before depuration, the concentrations of heavy metals such as Ni, Co, Fe, Mn, Cu, Pb and Zn were analysed and it was found that the Fe, Zn, Cu and Pb contents in all the three bivalve molluscs were above the prescribed limit which poses a significant health risk to bivalve consumers. To protect consumer food safety, depuration experiments were conducted at varying temperatures, salinities and body-sizes. The clams, mussels and oysters depurated under the room temperature depuration system (RTDS) showed a better reduction of heavy metals compared with low-temperature depuration system (LTDS). ANOVA showed clams and mussels depurated at RTDS significantly (p < 0.05) reduced the heavy metals than LTDS. However, there was no significant (p > 0.05) difference in oysters between RTDS and LTDS. Further, clams and mussels depurated at low salinity (15-psμ) showed high resistance against Pb reduction. But, all the heavy metals, particularly, Pb, Fe, Zn and Cu were effectively removed at higher salinity depuration (25-psμ and 35-psμ). Moreover, irrespective of the body-size of clams, mussels and oysters used for depuration, a significant (p < 0.05) reduction in all metals (Ni, Co, Fe, Mn, Zn, Pb and Cu) was observed. Relatively, the medium-size bivalves showed higher reductions compared to small-size bivalves. Based on the experiments conducted, we recommend 48 h depuration using the static system under room temperature (30 ± 1 °C) with a salinity range of (25-35 psμ) using medium-size bivalves (clam>30 mm; mussel >45 mm, and oyster >65 mm length) as optimum conditions for producing safe bivalves for consumption in the tropics.

Metal loadings in estuarine bivalve and gastropod shellfish in response to socioeconomic development in watershed

Metal contamination in estuary was monitored globally using shellfish while estuarine metal loadings were influenced by socioeconomic development in watershed, i.e., a watershed-estuary chain effect. Socioeconomic pattern of metal loadings in estuarine shellfish has scarcely been studied. Eight metals and metalloids (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) highly associated with anthropogenic activities were quantified in tissue and shell of bivalves and gastropods (two feeding-habits) among 7 estuaries along the Southeastern China coast in the period 2016-2019. Results indicated that Cu and Zn in shellfish had the greatest loadings at 1,663 and 6,828 mg kg^-1 dry mass in tissue and 387 and 151 mg kg^-1 dry mass in shell, respectively, in the most developed Estuary Yong. Metal loadings in tissue and shell of bivalves (6 common species) and gastropods (3 common species) in the estuaries were highly associated with urbanization and socioeconomic indicators in their watersheds. The socioeconomic patterns had evident shellfish class-specification and metal-dependency due to the feeding-habit. The class-specification was confirmed by the fractionation of stable isotope compositions for the socioeconomic pattern of Pb loadings in both tissue and shell. In short, both shellfish class-specification and metal-dependency hinted that multi-bioindicators might be required for a comprehensive understanding of the estuarine environment quality, in particular at two dimensions of water and sediment.

Occurrence of bisphenols and benzophenone UV filters in wild brown mussels (Perna perna) from Algoa Bay in South Africa

Bisphenols and benzophenone UV filters are contaminants present in a wide variety of plastic materials and consumer products. The scientific attention towards these contaminants has increased in recent years due to their presence in microplastics, their ubiquitous occurrence in the environment, and their known endocrine disrupting health effects. In this study, the occurrence of nine bisphenol and five benzophenone UV-filter analogues was assessed in wild brown mussels (Perna perna) collected from different sampling sites along the coast of Algoa Bay, South Africa. Eleven out of fourteen target analytes were detected, and bisphenol AP (BPAP) was detected for the first time in mussels, presenting the highest median concentration of 150 ng g^-1 dry weight (d.w.) and a detection frequency of 91%. Regarding benzophenone UV-filters, median concentrations of the analogues (across all sites) ranged from 2.01 to 10.6 ng g^-1 d.w., with benzophenone-1 (BzP-1) and benzophenone-3 (BzP-3) presenting the highest concentrations. Human exposure was assessed by estimating daily intakes (EDI) of the target analytes through mussel consumption. To our knowledge, this is the first study from the African continent on the occurrence of bisphenols and benzophenone UV-filters in a large population (n=138) of wild brown mussels.

Comparative Study of Potentially Toxic Nickel and Their Potential Human Health Risks in Seafood (Fish and Mollusks) from Peninsular Malaysia

Human exposure to highly nickel (Ni)-polluted environments through oral ingestion pathways may cause various pathological effects. This biomonitoring study aimed to assess the human health risk of potentially toxic Ni in 19 species of marine fishes from Setiu (Terengganu) and two popular seafood molluscs (mangrove snail Cerithidea obtusa and cockle Anadara granosa) from the coastal area of Peninsular Malaysia. The Ni levels of the three seafood types were found below the maximum permissible limit for Ni. The Ni target hazard quotient values of all seafood were lower than 1.00 for average and high-level (AHL) Malaysian consumers, indicating no Ni's non-carcinogenic risk of seafood consumption. It was also found that the calculated values of estimated weekly intake were below than established provisional tolerable weekly intake of Ni for both AHL consumers. It can be concluded that both the AHL consumption of seafood would not pose adverse effects of Ni to the consumers. This study provided a scientific basis for the food safety assessment of Ni and suggestions for risk management of potentially toxic Ni of seafood consumption in Malaysia.

Copper and Zinc Levels in Commercial Marine Fish from Setiu, East Coast of Peninsular Malaysia

Potentially toxic metals (PTMs) in edible marine fish have been widely reported from at least 15 different regions or countries in the literature. This evidently demonstrates the importance of monitoring the PTMs in fish fillets from a human health risk (HHR) point of view. This study aims to assess the HHR of Cu and Zn in 19 species of marine fish from popular marine fish loading sites at Setiu in Terengganu, on the east coast of Peninsular Malaysia, collected between August 2016 and February 2017. With overall ranges of concentrations (mg/kg dry weight) of Cu (1.50–7.83), and Zn (24.1–80.5), the 19 species of marine fishes from Setiu are good sources of these essential elements because they are below the maximum permissible limits set by seafood safety guidelines. The target hazard quotient values of Cu and Zn were lower than one, indicating non-carcinogenic risks of Cu and Zn in fish consumption. It was also found that the calculated values of the estimated weekly intake were below the established provisional tolerable weekly intake of Cu and Zn. It can be concluded that the consumption of fish from Setiu would not pose adverse effects from the PTMs to consumers. Nonetheless, continuous monitoring is necessary to ensure the safety of consumers who rely heavily on marine fish in Setiu coastal waters.

Baseline health risk assessment of trace metals in bivalve shellfish from commercial growing areas in the estuaries of Ashtamudi and Vembanad (Kerala, India)

Trace metal concentrations were monitored in the yellow clam (Paphia malabarica), green mussel (Perna viridis) and edible oyster (Crassostrea madrasensis) from growing areas in the Ashtamudi and Vembanad estuaries, Kerala. Samples of shellfish (clams n=26, mussels n=18, oysters n=36) and environmental parameters (salinity, temperature, pH and rainfall) were measured in these growing areas from July 2012 to December 2014. Ranges of mean annual concentrations (mg/kg) were Ni (0.46-0.65); Co (2.87-3.49); Fe (80.0-119.4); Mn (3.88-9.38); Zn (40.8-76.2); Pb (1.28-2.00); and Cu (1.59-4.38). In Ashtamudi, clams had higher mean concentrations of Ni, Co, Fe, Mn and Pb than oysters. Mean concentrations of Ni, Pb (in all species), Zn (in clams and mussels) and Cu (in mussels) did not exceed maximum permissible limits mandated by the Food Safety and Standards Authority of India. Mean Mn concentrations exceeded the World Health Organization guideline (1 mg/kg) in the three species while mean Fe concentrations in clams and oysters did not exceed the guideline (100 mg/kg). Target hazard quotients were generally ≤ 1, except for a few Pb results in clams and mussels. Although results suggest no health risk to consumers for the reference doses, daily intakes and elements considered, regular monitoring of trace metals is recommended to maintain consumer protection given increasing anthropogenic and climatic pressures on the shellfish growing areas.

Human health risk assessment associated with the consumption of mussels (Perna perna) and oysters (Crassostrea rhizophorae) contaminated with metals and arsenic in the estuarine channel of Vitória Bay (ES), Southeast Brazil

The estuarine channel of Vitória Bay was evaluated regarding bioaccumulation of metals (Al, Ba, Mn, Fe, Zn, Cu, Cr, Pb, Ni, Cd, Hg) and As in mollusks. Mussels from an aquaculture farm and transplanted into the estuary, whereas oysters were collected in situ in the same area. Concentrations of Al, Mn, Fe, Cr and As were higher in P. perna, whereas C. rhizophorae bioaccumulated more Ba, Zn and Cu. Arsenic concentrations in P. perna exceeded the limit of the Brazilian legislation in the outer estuary. Salinity seemed to influence metal uptake differently for each bivalve, with P. perna absorbing more metal at higher salinities and C. rhizophorae in areas of lower salinity. Hazard index (HI) >1 revealed risk for both bivalves for high level consumers. Target Cancer Risk (TCR) for As revealed threat for human health associated with the consumption of mussels and oysters from the study area.

Bioaccumulation of heavy metals in fish species of Iran: a review

Accumulation of heavy metals (HMs) in fish tissues is an important factor in monitoring the health and safety of aquatic ecosystems. Furthermore, fish are important parts of aquatic food chains and play a significant role in human health. Considering the significant role of fish in the diet of humans and their ability to transfer and biomagnify HMs, it is necessary to determine and study these contaminants in fish tissues, especially in the edible parts of the fish. In addition to the other ecological and economic services of aquatic ecosystems, water bodies, especially the Persian Gulf in the south and the Caspian Sea in the north of Iran, are the main sources of seafood for people in nearby areas, as well as people living farther away who have gained access to seafood due to the extensive trade of aquatic organisms. This study provides an overview of the health conditions of the aquatic ecosystems in Iran by monitoring HM bioaccumulation in fish species. For this purpose, we reviewed, summarized, and evaluated papers published on HM concentrations in fish species from different aquatic ecosystems, including the Persian Gulf, the Caspian Sea, wetlands, rivers, qanats, water reservoirs, lakes, and dams, with emphasis on species habitats, feeding habits, and target organs in accumulation of HMs. Generally, the highest concentrations of HMs were observed in fishes collected from the Persian Gulf, followed by species from the Caspian Sea. Species inhabiting the lower zone of the water column and carnivorous and/or omnivorous species showed the highest levels of HMs. Moreover, liver was the main accumulator organ for HMs.

Source and risk assessment of heavy metals and microplastics in bivalves and coastal sediments of the Northern Persian Gulf, Hormogzan Province

The objectives of the current study are to investigate the concentration, biological risks, chemical speciation, and mobility of of heavy metals and also the determination of their distribution, physicochemical characteristics, and abundance of microplastics in coastal sediments and edible bivalves in the Persian Gulf, the coastal area of Hormozgan Province. Sampling points were selected considering the location of industrial, urban and Hara forest protected areas. In November 2017, a total of 18 sediment samples from coastal sediments (top 0-10 cm) and the most consumed bivalve species in the region were collected from two stations, Lengeh and Bandar Abbas Ports. The average concentration of heavy metals (except for Ni and Cd) in the sediments were lower than their average shale and the upper continental crust. Enrichment factors revealed significant enrichment of Ni, Mn, Cr, Cd and As. The fractionation of heavy metals using the Community Bureau of Reference (BCR) sequential extraction scheme indicated the high bioavailability of Zn, As, Mn, and Co. In general, the highest concentration of Mo, Cd, Pb, Zn, Cr, Cu, Mn, Hg, and Sb was detected in areas with frequent human activities including Shahid Rajaee Port, Shahid Bahonar Port, and Tavanir station. Shahid Rajaee and Shahid Bahonar Ports are the most important ports on the coast of Hormozgan province. The Risk Assessment Code calculated for the study elements indicates that As, Co, Zn, and Cu pose a moderate environmental risk a threat to the aquatic biota. Health risks of most heavy metals arising from bivalves consumption were safe, except for As which is associated with the high target cancer risk values. With reference to the type of microplastics found, they were mainly fibeours with lengths ranging between 100 and 250 μm in sediments and bivalves. Most of the microfibers found in the sediments were made of polyethylene terephthalate (PET) and polypropylene (PP), and the fibers found in the bivalves were made of PP.

Human Health Risk Assessments of Trace Metals on the Clam Corbicula javanica in a Tropical River in Peninsular Malaysia

This study aimed to analyse ten trace metal concentrations in the edible part of the freshwater clam Corbicula javanica and to provide a critical assessment of the potential risks to human health through consumption of this clam as food based on well-established indices and food safety guidelines. The clams were captured from a pristine original site and transplanted to other sites with different environmental qualities. The trace metal levels in the edible total soft tissue (TST) of the clam were below those of the food safety guidelines referred to except for Pb, which exceeded the permissible limit set by the European Commission (2006) and the US Food and Drug Administration/ Center for Food Safety and Applied Nutrition); Interstate Shellfish Sanitation Conference. (USFDA/CFSAN; ISSC) (2007). The estimated daily intake (EDI) values of the clam were found to be lower than the oral reference dose and the calculated target hazard quotient (THQ) and total THQ were found to be less than 1. Therefore, in conclusion, the human health risk for consumption of TST of C. javanica at both average and high-level were insignificant regardless of the environment it was exposed to.

Current status of food safety hazards and health risks connected with aquatic food products from Southeast Asian region

Food safety issues associated with aquatic food products become more important with the increasing consumption and followed by its ongoing challenges. The objective of this paper is to review the food safety hazards and health risks related to aquatic food products for the Southeast Asian region. These hazards can be categorized as microplastics (MPs) hazard, biological hazards (pathogenic bacteria, biogenic amines, viruses, parasites), and chemical hazards (antimicrobial, formaldehyde, heavy metal). In different Southeast Asian countries, the potential health risks of aquatic food products brought by food hazards to consumers were at different intensity and classes. Among all these hazards, pathogenic bacteria, antimicrobials, and heavy metal were a particular concern in the Southeast Asian region. With environmental changes, evolving consumption patterns, and the globalization of trade, new food safety challenges are created, which put forward higher requirements on food technologies, food safety regulations, and international cooperation.

Integrated Monitoring with Moss-Bag and Mussel Transplants in Reservoirs

For the first time, transplants with moss-bags and mussels together were applied to study the water quality in standing water bodies. The tested species: Fontinalis antipyretica Hedw. and Sinanodonta woodiana (Lea, 1834) were collected from unpolluted sites and analyzed to obtain background levels. Then, the moss and mussels were left in cages for a period of 30 days in three reservoirs where both are not present naturally. Two of the reservoirs suffer from old industrial contamination and one is affected by untreated wastes. Twenty-four compounds were studied, among them trace elements Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Zn and organic priority substances: six polybrominated diphenyl ethers (PBDEs) congeners and short-chain chlorinated paraffins (SCCPs). The trace element accumulation was significant after the exposition period in all studied stations. PBDEs and SCCPs were also accumulated up to two times more in the moss tissues. PBDEs in the mussels exceeded the environmental quality standard (EQS). The applied combined transplants, and especially the moss-bags, revealed severe contamination with heavy metals not detected by the water samples. The moss and the mussel followed a different model of trace element and PBDEs accumulation. The SCCPs levels were alarmingly high in all plant samples. The study confirmed PBDEs and SCCPs as bioaccumulative compounds and suggested that an EQS for SCCPs in biota needs to be established.

Effects of location, climate, soil conditions and plant species on levels of potentially toxic elements in Chinese Prickly Ash pericarps from the main cultivation regions in China

The presence of potentially toxic mineral elements is often reported in soil, fruits and vegetables. The concentrations of these are influenced by location, climate and soil conditions, and plant species. This study reports levels of aluminium (Al), arsenic (As), cadmium (Cd), lead (Pb), manganese (Mn) and nickel (Ni) in the soils where Chinese Prickly Ash - Zanthoxylum bungeanum (ZB) and Z. armatum (ZA) are grown. Soil and pericarp samples were taken from 72 ZB and ZA plantations in 12 provinces. The soil pollution index (PI) was generally low for As (0.04-0.35), Pb (0.01-0.74) and Ni (0.15-1.06). The PI was higher for Cd (0.06-6.99) and was assessed at three categorical levels: 'low' (in 26% of soils), 'moderate' (in 67% of soils) and high (in 7% of soils). The majority (94%) of soils were slightly polluted with Cd with the integrated pollution index in the range 0.17-2.02. More than 60% of pericarp samples posed a high non-cancer health risk based on the hazard index, while 43% of pericarp samples posed a considerable cancer risk based on the incremental lifetime cancer risk. The mean temperature and the mean relative humidity contributed most significantly (28% and 10%, respectively) to variation in the concentrations of potentially toxic elements in the pericarps. This study provides a comprehensive report on the concentrations of potentially toxic elements in the soils and associated pericarps, and the effects of location, climate, and soil on the levels of potentially toxic elements in the soil and pericarps, including the effects of tree species.

Trophic transfer affects cytogenetic and antioxidant responses of the mussel Mytilus galloprovincialis to copper and benzo(α)pyrene

The impacts of environmental pollutants on marine organisms can be determined by the routes of exposure. Various routes of exposure, including dietary exposure and waterborne exposure with or without feeding, were applied to study the cytogenetic responses in marine mussels Mytilus galloprovincials to typical pollutants, BaP (53.74 ± 19.79 μg/L) and Cu (47.38 ± 3.10 μg/L). The increased DNA strand breaks and micronucleus formation were found in haemocytes of mussels via the dietary exposure, indicating the vital role of trophic transfer in toxicity induction. The deeper exploration to relate BaP induced cytogenetic alterations with key antioxidant defense factors, SOD and GST, was performed under different exposure routes. The results revealed the significantly inhibited SOD activity via the trophic transfer, suggesting more direct or prompt role of SOD in antioxidant defense. On contrary, gene expressions of both sod and gst were up-regulated upon all routes of exposures, and showed negative correlation with enzyme activities. The results suggested the asynchronous regulation of studied antioxidant factors at transcriptional and enzyme functional level in mussels upon the change of exposure routes. The study brings out the first observation of trophic transfer influenced cytogenetic and antioxidant responses to pollutants and their alterative risk to marine organisms.

Bioaccumulation and health risk assessment of heavy metals to bivalve species in Daya Bay (South China Sea): Consumption advisory

Bivalves are one of the key components of the biogeochemical cycle in the marine system, and respond to heavy metal (HM) sensitively as filter feeders. To determine relationship of HMs in edible bivalve and seawater and HM effects on human health when digesting bivalves, HMs were analyzed in bivalves and seawater. The results showed that the mean HM concentrations in bivalves decreased in the order of Zn > Cu > Cr > Pb > As > Cd > Hg. Generally, all the bioconcentration factor values of bivalves were higher than 100, suggesting that bivalves have a high bioaccumulation ability. Nonmetric multidimensional scaling analysis indicated that all bivalves have a high bioaccumulation capacity for Cu and Zn. It was found that there are health risks associated with consuming bivalves, and children are more vulnerable than adults. Finally, the maximum allowable consumption rates of non-carcinogenic and carcinogenic risk were determined. These results provide the underlying insights needed to guide the consumption of seafood.

Bioaccumulation and human health risk of shellfish contamination to heavy metals and As in most rapid urbanized Shenzhen, China

Despite the benefits of shellfish consumption, the bioaccumulation of heavy metals in shellfish can endanger consumer's health. The consumption of seafood in Shenzhen (a fast-developing metropolis in China) has received more and more attention. Arsenic (As), cadmium (Cd), copper (Cu), mercury (Hg), and lead (Pb) in ten common shellfish species and associated health risks were analyzed for Shenzhen's consumers by evaluating estimated weekly intake (EWI), non-carcinogenic and carcinogenic health risks to children, adolescents, and adults. In this study, 50 shellfish samples were collected in total. The results showed that the levels of inorganic arsenic (iAs) in Babylonia areolata exceeded the maximum permissible limit set by the food safety guidelines (0.5 mg/kg), while other elements were below the limit in the present guidelines (Ministry of Health of the People's Republic of China, GB 2762-2012). EWI values of children, adolescents, and adults were all lower than provisional tolerable weekly intakes (PTWIs) of all shellfish species. The analysis of total target hazard quotients (TTHQ) showed that the ingested B. areolata in children, adolescents, and adults were all at non-carcinogenic risks; the consumption of Argopecten irradians and Chlamys farreri would pose non-carcinogenic risks for children only. In all age groups, the consumption of A. irradians, B. areolata, C. farreri, and Crassostrea ariakensis would lead to lifetime cancer risk due to Cd bioaccumulation, with toxicity of Pb and iAs to be acceptable and negligible.

Assessment of Human Health Risk of Toxic Elements Due to Cinnamon Ingestion in the Diet

Recent studies highlighted the beneficial action of cinnamon on postprandial glycemia and LDL-cholesterol concentrations, both in healthy subjects and type 2 diabetic patients. Inclusion of 3 to 6 g of cinnamon in diet revealed a beneficial effect on glucose metabolism control in non-diabetic adults during postprandial period. Given the levels of toxic elements present in cinnamon species from different countries, such large daily intakes of cinnamon can easily exceed their maximum permissible limits and, consequently, induce adverse health effects. This study aimed to investigate the elemental concentration profile in cinnamon powder products available in the Portuguese market and to assess the cumulative non-carcinogenic risk to human health due to the exposure to mixtures of such elements through the inclusion of 6 g of cinnamon in diet. Concentrations of Cu, Zn, Fe, Al, Cl, Mn, and Sr were determined by wavelength dispersive X-ray fluorescence spectroscopy in different lots of eight branded and one bulk cinnamon powder products. Linear mixed models have revealed significant differences in concentrations of Zn, Fe, Al, and Cl between brands. In particular, bulk cinnamon samples presented the highest contents of Fe (475.0-490.0 mg kg^-1) and Al (1139.0-1336.0 mg kg^-1). The non-carcinogenic risk was assessed following EPA's guidelines through the hazard quotient (HQ). Estimated HQ values were lower than the USEPA guideline of 1. Additionally, the hazard index (HI), representing the combined non-carcinogenic effects of all toxic elements, revealed no potential human health risk for heavy consumers of cinnamon (HI = 0.660). AbstractGraphical ᅟ.

Dietary Intake of Essential, Toxic, and Potentially Toxic Elements from Mussels (Mytilus spp.) in the Spanish Population: A Nutritional Assessment

The levels of forty-three elements were determined in fresh, preserved, and frozen mussels (n = 208) with the purpose of evaluating their contribution to the recommended dietary intake of essential elements and their potential risk to Spanish consumers’ health. We found relevant differences in the element content in relation to the mode of conservation of mussels as well as in relation to their geographical origin, brand, or mode of production. According to our estimates, mussels are important contributors to the intake of most essential elements, contributing almost 70% of daily requirements of Se, 30–35% of Mo, Zn, and Co, and around 15% of Fe. At the same time, the pattern of average consumption of mussels in Spain does not seem to imply an excessive risk associated with any of the 36 toxic elements studied. However, it should be noted that, in the high percentile of consumption the exposure to Cd and As may be high, in particular that associated with the consumption of fresh and/or frozen mussels. According to the results of this study, a moderate consumption of mussels can be recommended as a valuable and safe source of trace elements.

Heavy metal contamination and health risk assessment for children near a large Cu-smelter in central China

Nonferrous metallurgy is causing significant concerns due to its emissions of heavy metals into environment, degrading environmental quality, and consequently posing high risks to human health. In this study, the concentration levels of Cadmium (Cd), Copper (Cu), Lead (Pb), and Arsenic (As) were investigated in soil, crop, well water, and fish samples collected around the Daye Copper Smelter in Hubei province, China, and the potential health risks were assessed for local children. The results showed that soils near the smelter were heavily polluted by Cd, Cu, Pb, and As, with the mean concentrations of 4.87, 195.26, 92.65, and 35.84 mg/kg, respectively, which were significantly higher than the values of soil Cd (0.18 mg/kg), Cu (32.84 mg/kg), Pb (28.46 mg/kg), and As (13.65 mg/kg) in the reference area (p < 0.001). The concentrations of Cd and As in vegetable samples collected from smelter-affected area exceeded the maximum permissible level (MPL) for food in China by 82% and 39%, respectively. The concentrations of Cd and Pb in rice grain harvested from smelter-affected area were 9.35 and 1.35 times higher than the corresponding MPL, respectively. The concentrations of Cd, As, and Cu in fish muscle from smelter-affected area exceeded the national MPL by 72%, 41%, and 24% of analyzed samples, respectively. The concentrations of Cd (p < 0.05) and As (p < 0.01) in well water were significantly higher in the smelter-affected area than those in the reference area, respectively. The health risks to local children in the smelter-affected area were 30.25 times higher than the acceptable level of 1, and most of the risks were resulted from Cd (46%), As (27%) and Pb (20%). The intake of crops was a major source (78%) to health risks for local children.

Human exposure to trace elements via consumption of mussels Mytilus galloprovincialis from Boka Kotorska Bay, Montenegro

In order to assess human health risks via consumption of potentially toxic mussels, the concentrations of Al, Ba, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Sr, Zn and Hg were studied in Mytilus galloprovincialis collected from the coastal area of Montenegro. By two approaches for the human health risk assessment (HHRA), considering oral reference doses by the United States Environmental Protection Agency (US EPA) and provisional tolerable intakes by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), it has been revealed that despite the fact that trace element levels do not exceed the defined limits for mussels, they can be limiting factors for the mussel consumption. Specifically, it was noticed that the levels of Co, Pb, Cd and Li could be the limiting factors for the consumption of mussels from this coastal area. Al and Li data obtained in this study are especially important since these two elements have not been previously studied in M. galloprovincialis. Furthermore, taking into account the significant differences in concentrations of elements in different seasons, the study confirmed the starting assumption that in the calculations for the HHRA the average concentrations of elements in samples taken in different seasons during a longer period should be used.

Toxic metals in Perna viridis mussel and surface seawater in Pasir Gudang coastal area, Malaysia, and its health implications

Contamination of toxic metals in P. viridis mussels has been prevalently reported; hence, health risk assessment for consuming this aquaculture product as well as the surrounding surface seawater at its harvesting sites appears relevant. Since Kampung Pasir Puteh, Pasir Gudang is the major harvesting site in Malaysia, and because the last heavy metal assessment was done in 2009, its current status remains unclear. Herein, flame atomic absorption spectrometry and flow injection mercury/hydride system were used to determine the concentrations of Pb, Cd, Cu and total Hg in P. viridis mussels and surface seawater (January-March 2015), respectively. Significantly higher concentrations of these metals were found in P. viridis mussels (p < 0.05) than that of surface seawater samples. The concentrations for Pb (4.27-6.55 μg/g) and Cd (1.55-2.21 μg/g) in P. viridis mussels exceeded the maximum permitted proportion prescribed by the Malaysian law. The concentrations of all metals in surface seawater also violated the Malaysia Marine Water Quality Criteria and Standards. Significant (p < 0.05) and high strength of association (r = 0.787) observed between Pb concentration in P. viridis mussel with the surface seawater indicates its possible application for inferring Pb concentrations in the mussel. Since both the calculated target hazard quotient and hazard index for Pb and Cd exceeded 1, the possible detrimental health impacts on human for consuming P. viridis mussels from this rearing site cannot be ignored. Hence, promoting continuous monitoring programmes and developing efficient toxic metal removal techniques prior to entering the market are required.

Metals in Mytillus galloprovincialis (Lamarck 1819) and Ensis directus (Conrad 1883): Risk Assessment

The study has been conducted with inductively coupled plasma optical emission spectrometry to determine the content of toxic heavy metals, macroelements, and essential elements in two species of bivalves of commercial interest in the Canary Islands: the Mediterranean mussel ( Mytillus galloprovincialis, Lamarck 1819) and the razor clam ( Ensis directus, Conrad 1883). The study included 40 samples corresponding to 20 specimens of each species acquired from fishmongers on the island of Tenerife. E. directus had higher levels of metals, except for B, Cd, Na, and Zn (0.98, 0.02, 2,006.93, and 15.07 mg/kg, respectively) compared with those in M. galloprovincialis, B, Cd, Na, and Zn (2.67, 0.12, 2,267.7, and 22.27 mg/kg, respectively). In both bivalve molluscs, the maximum limits established by European legislation on food for human consumption were not exceeded. Likewise, the estimated daily intakes for the toxic metals Pb and Cd were below the admissible daily intakes.

Potential health risks via consumption of six edible shellfish species collected from Piura - Peru

Scallops and their potential predators were collected in Sechura Bay and in front of the Illescas Reserved Zone (north Peru), during El Niño-Southern Oscillation (ENSO) 2016, and analyzed for the metals chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb). This study showed that ~20% of the molluscs exceeded the maximum residual levels (MRLs) for human consumption in inorganic As, while ~30% of the crustaceans did. For Cd, around 10% and 40% of the molluscs and the crustaceans were above the MRLs, respectively. The cephalopod Octopus mimus exhibited As concentrations, but not Cd concentrations, that exceeded the MRLs. Cr, Ni, Cu, Zn and Pb in muscle exhibited generally concentrations below the MRLs. Integrated risk indices were estimated to determine if there is a health risk for consumption. Target hazard quotients (THQs) and total hazard indices (HIs) were mostly < 1, implying no human health risk. Provisional tolerable weekly intake (PTWI) for Cd was exceeded in Bursa ventricosa at Illescas Reserved Zone. Target cancer risks (TRs) for inorganic As were always higher than the threshold (1 × 10^-6), therefore an actual cancer risk is present.

Biological risk assessment of heavy metals in sediments and health risk assessment in bivalve mollusks from Kaozhouyang Bay, South China

The concentrations of heavy metals (Cd, Pb, Cr, Ni, Cu, Zn, Hg and As) in surface sediments and bivalve mollusks in Kaozhouyang Bay were investigated. A biological risk analysis of the sediments indicated that ten sites (about 76.92% of the total number of sites) had a 21% incidence probability of toxicity. A health risk analysis of the bivalve mollusks indicated that Cu and As posed low risks to consumer health. On the basis of the target hazard quotient (THQ), adverse effects may occur based on total THQ (TTHQ). The highest TTHQ was found in the species, Ostrea rivularis, which had the highest capacity for the bioaccumulation (factor > 38) of Cd.

Evaluating a 5-year metal contamination remediation and the biomonitoring potential of a freshwater gastropod along the Xiangjiang River, China

Effective remediation of heavy metal pollution in aquatic systems is desired in many regions, but it requires integrative assessments of sediments, water, and biota that can serve as robust biomonitors. We assessed the effects of a 5-year metal contamination remediation along the Xiangjiang River, China, by comparing concentrations of trace metals in water and surface sediments between 2010-2011 and 2016. We also explored the trace metal biomonitoring potential of a freshwater gastropod (Bellamya aeruginosa). Metal concentrations in water (means and ranges) dropped over time to within permissible limits of drinking water guidelines set by China, USEPA, and WHO in 2016. Although sediment means and ranges of Cd, Pb, Zn, and Mn also diminished with remediation, those for Cr and Cu slightly increased, and all six metals retained concentrations higher than standards set by China. All metals in sediments could also be associated with anthropogenic inputs using a hierarchical clustering analysis, and they generate high potential ecological risks based on several indices, especially for Cd and As. The bio-sediment accumulation factors of all measured trace metals in gastropod soft tissues and shells were lower than 1.0, except for Ca. Trace metal contents in gastropods were positively correlated with those in water and surface sediments for As (soft tissues) and Cr (shells). Collectively, our results do not yet highlight strong beneficial effects of 5-year remediation and clearly illustrate the heavy metal pollution remaining in Xiangjiang River sediment. Additional physical, chemical, and biological measurements should be implemented to improve sediment quality. We further conclude that gastropod soft tissues and shells can be suitable biomonitors of spatial differences in some heavy metals found within river sediments (e.g., As, Cr).

Assessment of trace metal accumulation in native mussels (Brachidontes rodriguezii) from a South American temperate estuary

The present work provides the first results in heavy metal bioaccumulation in the autochthonous mussel Brachidontes rodriguezii from the Bahía Blanca Estuary (Argentina), one of the most important coastal environments of South America, subjected to different anthropogenic pressure. The study is based on the detection of Cd, Cu, Pb, Mn, and Fe in mussels' soft tissue and sediments' fine fraction by means of inductively coupled plasma atomic emission spectroscopy (ICP-OES), in order to analyze the potential relationship between both components of the aquatic system. Additionally, different indices are calculated with the purpose of obtaining detailed data. The heavy metal burden in mussels varied seasonally, showing a clearer pattern for the stations located in the internal area of the estuary. Metals exhibited maximum values in summer and to a lesser extent in winter, followed by a decrease during spring. Multiple international guideline assessment allowed classifying the area as moderately polluted, including a low range for Cd and medium for Cu and Pb. Moreover, the average detected levels were within the measured ranges in other coastal areas. Regarding human health, trace metal content in mussels met the national and international standards for safe consumption.

Potential human health risk from consumption of metallic elements-contaminated benthic mollusks from Don Hoi Lot sandbar, Thailand

Environmental pollutants have raised more concerns for human health risk, especially via consumption of contaminated food. Terrestrial as well as aquatic animals are capable of bioaccumulation a variety of toxic substances including metallic elements. With increasing anthropogenic activities along the coastal areas, living organisms have more chances to be exposed to released contaminants. In this study, seven metallic elements (Cd, Cu, Fe, Mn, Ni, Pb and Zn) were determined in sediments and water from Don Hoi Lot sandbar, Samutsongkharm province, Thailand. Potential human health risks via the consumption of two benthic bivalves Solen corneus (Larmarck, 1818) and Meretrix meretrix (Linnaeus, 1758) were also estimated using the target hazard quotients (THQs). The variations of metallic element concentrations were apparent between wet and dry season. Fe was the predominate metallic element in the sediment and the remaining were Mn>Pb>Zn>Ni>Cu>Cd. Whereas metallic element concentrations in water were Pb>Ni>Fe>Zn>Cu>Mn>Cd. PCA analysis confirmed that the contaminations of these metallic elements were from Mae Klong river surface water. Most Pb THQ values in both S. corneus and M. meretrix were >1 indicating that human health risk is of concern. However, the sum of THQs of an individual metallic element should also be considered since multiple metallic elements exposure is so common.

Recent Advances on Magnetic Relaxation Switching Assay-Based Nanosensors

Magnetic relaxation switching assay (MRSw)-based nanosensors respond to the changes of transverse relaxation time (T₂) of water molecules resulted from the analyte-induced aggregation and disaggregation of magnetic nanoparticles (MNPs). This strategy has been widely applied to the detections of various substrates from heavy metal ions to organic pollutants, proteins, nucleic acids, bacteria and viruses, and specific cells. Compared with other nanosensors, MRSw-based nanosensors not only are free from the background interferences, signal bleaching, and quenching but also overcome light scattering from samples without pretreatments. Therefore, MRSw-based nanosensors have been developed as real-time and on-site detection platforms for environmental protection, food safety, and risk assessment. This review summarizes the latest developments of the principles, the applicable magnetic nanoparticles, and the exploited environmental and biological applications of MRSw-based nanosensors.