Microplastics in commercially important seafood species is an emerging area of food safety concern. While there have been reports of plastic particles in the gastrointestinal tract of several species, presence of microplastics in edible fish tissues has not yet been reported from India. This study examined the presence of microplastics in the edible (muscle and skin) and inedible (gill and viscera) tissues of nine commercially important pelagic fish species from Kerala, India. A total of 163 particles consisting mainly of fragments (58%) were isolated. Out of 270 fishes analysed (n = 30 per species), 41.1% of the fishes had microplastics in their inedible tissues while only 7% of fishes had microplastics in their edible tissues. The quantity of microplastics in inedible tissue was significantly larger in filter feeders than, that in visual predators (p < 0.05). The average abundance of microplastics in edible tissues was 0.07 ± 0.26 items/fish (i.e., 0.005 ± 0.02 items/g) and was 0.53 ± 0.77 items/fish (i.e., 0.054 ± 0.098 items/g) in inedible tissues. The results suggest the possibility of human intake of microplastics by the consumption of pelagic fishes from this region, albeit in small quantities.

Micro-plastic particles in the world's oceans represent a serious threat to both human health and marine ecosystems. Once released into the aquatic environment plastic litter is broken down to smaller pieces through photo-degradation and the physical actions of waves, wind, etc. The resulting particles may become so small that they are readily taken up by fish, crustaceans and mollusks. There is mounting evidence for the uptake of plastic particles by marine organisms that form part of the human food chain and this is driving urgent calls for further and deeper investigations into this pollution issue.The present study aimed at investigating for the first time the occurrence, amount, typology of microplastic litter in the gastrointestinal tract of Solea solea and its spatial distribution in the northern and central Adriatic Sea. This benthic flatfish was selected as it is a species of high commercial interest within the FAO GFCM (General Fisheries Commission for the Mediterranean) area 37 (Mediterranean and Black Sea) where around 15% of the overall global Solea solea production originates.The digestive tract contents of 533 individuals collected in fall during 2014 and 2015 from 60 sampling sites were examined for microplastics. These were recorded in 95% of sampled fish, with more than one microplastic item found in around 80% of the examined specimens. The most commonly found polymers were polyvinyl chloride, polypropylene, polyethylene, polyester, and polyamide, 72% as fragments and 28% as fibers. The mean number of ingested microplastics was 1.73 ± 0.05 items per fish in 2014 and 1.64 ± 0.1 in 2015. PVC and PA showed the highest densities in the northern Adriatic Sea, both inshore and off-shore while PE, PP and PET were more concentrated in coastal areas with the highest values offshore from the port of Rimini.

Sewage treatment works and stormwater outfalls were identified as sources of microplastics in the Victoria Harbor, Hong Kong. Local treated sewage and stormwater effluents contained up to 10,816 pieces per m³ of microplastics, mainly polyethylene (PE) and polypropylene (PP), being discharged at an average rate of 3.5 mg per capita daily. Bioaccumulation of microplastics in marine fish collected from the vicinity of the effluent discharge outfalls was also studied. The temporal variations of microplastics in terms of abundance, shape and polymer type in fish were found consistent with those in the effluents and surface water. The abundance of microplastics was significantly higher in March 2017 (dry season). Microplastics in fish were predominantly in fiber form and identified as PE and PP. The observed temporal variations suggest uptake of microplastics by fish from the treated sewage and stormwater effluents.

Selected potentially toxic elements (PTEs), including As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Se, and Zn, along with microplastic particles (MPs) were characterized in the muscle of seafood species in order to study potential health risk and also investigate biomagnification of the contaminants. The results revealed high levels of the analyzed PTEs and MPs in crustaceans. The cancer risk among the consumer population (adult and children) posed by As is higher than the acceptable lifetime risk of 10⁻⁴. Portunus plagicus and Platycephalus indicus had the highest and lowest amount of MP particles in their muscles, respectively, among investigated species. Finally, PTEs (except Hg) and MPs are not biomagnified in the collected species. The results of this research emphasize the importance of accounting for health risks posed by potential pollutants via consumption of contaminated seafood.

Recent studies have demonstrated the negative impacts of microplastics on wildlife. Therefore, the presence of microplastics in marine species for human consumption and the high intake of seafood (fish and shellfish) in some countries cause concern about the potential effects of microplastics on human health. In this brief review, the evidence of seafood contamination by microplastics is reviewed, and the potential consequences of the presence of microplastics in the marine environment for human food security, food safety and health are discussed. Furthermore, challenges and gaps in knowledge are identified. The knowledge on the adverse effects on human health due to the consumption of marine organisms containing microplastics is very limited, difficult to assess and still controversial. Thus, assessment of the risk posed to humans is challenging. Research is urgently needed, especially regarding the potential exposure and associated health risk to micro- and nano-sized plastics.

Muscles of 115 North Pacific albacore (ALB, Thunnus alalunga) and 75 Pacific bigeye tuna (BET, Thunnus obesus), collected from 2001 to 2006, were analyzed. No ALB, but 13 large BET had organic mercury (OHg) concentrations exceeding 1μgg−1 wet weight. For both ALB and BET, total mercury (THg) and OHg concentrations were significantly and positively correlated with fork length (FL) and body weight. The muscle Hg bioaccumulation rates of BET were higher than those of ALB, particularly in the adult fish. Moreover, the lines had crossover points among the two species that imply the young BET (FL<110cm) contains lower muscle Hg concentrations than ALB of the same size. The suggested weekly dietary intake of ALB and small-BET meats is 340g, and of BET meat it is 150g for a 60-kg person based on the provisional tolerable weekly intake (PTWI) of methylmercury set by the WHO.

Selenium’s (Se) protective effects against mercury (Hg) toxicity have been demonstrated; however, this is seldom considered in health assessments, where dietary exposure is still evaluated by Hg concentration alone. Se:Hg ratios and selenium health benefit values (Se HBVs) offer a more comprehensive seafood safety model. Here we describe total mercury (THg), methylmercury (MeHg) and Se concentrations in fish from a Hg-polluted estuary. Spatial variation in THg, MeHg and Se was evident, though all regions maintained Se:Hg ratio values >1. Se HBV varied between regions and in one region mean negative values (−5.17) were evident. This study provides the first evidence that quoting a single all-encompassing Se HBV is not appropriate when species demonstrate strong site fidelity. It highlights the need for research into Se–Hg relationships in environments with established Hg pollution and reinforces the assertion that Se concentration be considered in assessments of human health risk to Hg exposure.

In this study selected marine species from north Persian Gulf ecosystems were collected to investigate the concentration of 15 trace elements (Al, As, Co, Cr, Cu, Fe, Li, Mo, Ni, Pb, Se, Sr, V, Zn and Hg) in muscle and liver tissues for the purpose of evaluating potential health risks for human consumers. The results indicated that Fe, Zn, Sr, Cu and As are the most abundant TEs in the tissues of the species. The concentration of Cu in P. semisulcatus and As in most investigated species pose the highest risk of exposure. The carcinogenic risk values indicate that As and Ni concentrations in the species are above the acceptable lifetime risk for adults and children in most of the species. The margin of exposure risk approach indicated that the risk of detrimental effects due to dietary Pb intake for age groups is low, except for consumers of T. tonggol.