Potential health risk assessment of selected metal concentrations of Indian backwater oyster, (Crassostrea madrasensis) in Sri Lanka.

The study was conducted to assess the health risks of selected metals in cultured and wild Crassostrea madrasensis in Sri Lanka over 13 months. Metal concentrations varied monthly, and Zn and Cu concentrations significantly varied between cultured and wild oysters. The mean metal concentrations (mg kg-1) were accumulated in order of Zn (1220.60) > Mg (496.97) > Fe (356.30) > Cu (114.95) > Pb (23.20) > Cd (6.15) > As (3.09) > Hg (0.12). The metal concentrations were well below the standard guidelines given by international standards except for Pb, Cd, As and Zn. The weekly intakes of Hg, Cu, Fe, and Zn from C.madrasensis were below the Provisional Tolerable Weekly Intake while Cd exceeded the established limit. The calculated non-carcinogenic and carcinogenic risk indices for Hg, As, Pb and Zn were within safe levels and the values for Cd exceeded the limit revealing carcinogenic results with long-term consumption. Hence, creating proper awareness and a suitable depuration system ensures human health and supports export-oriented markets.

Microplastics (MPs) in marine food chains: Is it a food safety issue?

The enormous usage of plastic over the last seven decades has resulted in a massive quantity of plastic waste, much of it eventually breaking down into microplastic (MP) and nano plastic (NP). The MPs and NPs are regarded as emerging pollutants of serious concern. Both MPs and NPs can have a primary or secondary origin. Their ubiquitous presence and ability to sorb, desorb, and leach chemicals have raised concern over their presence in the aquatic environment and, particularly, the marine food chain. MPs and NPs are also considered vectors for pollutant transfer along with the marine food chain, and people who consume seafood have began significant concerns about the toxicity of seafood. The exact consequences and risk of MP exposure to marine foods are largely unknown and should be a priority research area. Although several studies have documented an effective clearance mechanism by defecation, significant aspect has been less emphasized for MPs and NPs and their capability to translocate in organs and clearance is not well established. The technological limitations to study these ultra-fine MPs are another challenge to be addressed. Therefore, this chapter discusses the recent findings of MPs in different marine food chains, their translocation and accumulations potential, MPs as a critical vector for pollutant transfer, toxicology impact, cycling in the marine environment and seafood safety. Besides, the concerns and challenges that are overshadowed by findings for the significance of MPs were covered.

Mitigating the impact of mercury contaminants in fish and other seafood-A review.

Mercury (Hg) is a well-known toxicant which enters the marine environment by both natural and anthropogenic sources. Consumption of fish and other seafood that contain methylmercury (MeHg) is a leading source of Hg exposure in humans. Considerable efforts have been made to mitigate the Hg presence and reduce its risks to humans. In this review the acknowledged methods of mitigation are summarized such as regulation and maximum allowable limits, and culinary treatments. In addition, selected industrial level trials are reviewed, and studies on Hg intoxication and the protective effects of the essential trace element, selenium (Se), are discussed. In view of the available literature, Hg reduction in fish and other seafood on a large industrial scale still is largely unsuccessful. Hence, more research and further attempts are necessary in order to better mitigate the Hg problem in fish and other seafood products.

Critical review of micro-extraction techniques used in the determination of polycyclic aromatic hydrocarbons in biological, environmental and food samples.

Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous environmental contaminants and their accurate determination is very important to human health and environment safety. In this review, sorptive-based micro-extraction techniques [such as Solid-Phase Micro-extraction (SPME), Stir Bar Sorptive Extraction (SBSE), Micro-extraction in Packed Sorbent (MEPS)] and solvent-based micro-extraction [Membrane-Mediated Liquid-Phase Micro-extraction (MM-LPME), Dispersive Liquid-Liquid Micro-extraction (DLLME), and Single Drop Micro-extraction (SDME)] developed for quantification of PAHs in environmental, biological and food samples are reviewed. Moreover, recent micro-extraction techniques that have been coupled with other sample extraction strategies are also briefly discussed. The main objectives of these micro-extraction techniques are to perform extraction, pre-concentration and clean up together as one step, and the reduction of the analysis time, cost and solvent following the green chemistry guidelines.

Critical review of mercury contamination in Sri Lankan fish and aquatic products.

Mercury (Hg) in fish and aquatic products is a potential threat to human health and international trade, and guidelines of international advisory bodies are established for assessing Hg in these foods. As fish are the most consumed animal protein in Sri Lanka, this assessment summarises for the first-time total mercury concentrations in Sri Lankan marine and freshwater fish, invertebrates, aquatic plants, and fisheries products. It reveals that Hg levels in fish and other edible aquatic species are mostly below the published safety limits, except for certain top trophic level fish (swordfish, tuna, marlin). The review also highlights gaps in Sri Lankan Hg assessments such as a total lack of data for methyl­mercury in these aquatic species and food products. This data compilation and assessment will serve as an initial baseline for comparison with results from future monitoring and research studies in Sri Lanka while adding to the world-wide Hg database.

Mercury and cadmium distribution in yellowfin tuna (Thunnus albacares) from two fishing grounds in the Indian Ocean near Sri Lanka.

Mercury (Hg) and cadmium (Cd) are contaminants of great environmental concern due to their natural and anthropogenic origin, their ability of bioaccumulate through the food chain and their harmful effects on human health. In this study, the Hg and Cd accumulation in the muscle of 65 yellowfin tuna (Thunnus albacares) collected from two different catching sites of the Indian Ocean near Sri Lanka were evaluated. The samples were mineralized using microwave accelerated digestion, and the metals were detected by atomic absorption spectroscopy (AAS). The metal levels were not significantly different between the two sites (p > 0.05), and the average Hg and Cd concentrations were 0.48 ± 0.35 mg/kg and 0.017 ± 0.024 mg/kg, (wet weight basis) respectively. Only 6 (9.2%) and 2 samples (3.1%) exceeded the European Commission limits for Hg (1 mg/kg) and Cd (0.01 mg/kg), respectively. A comparatively strong positive correlation was observed between the THg concentration and the weight of the fish. However, there was no clear relationship between the concentration and size for Cd. These findings provide an understanding of the Hg and Cd distribution in yellowfin tuna in two fishing grounds in the Indian Ocean near Sri Lanka.

Mercury and cadmium in swordfish and yellowfin tuna and health risk assessment for Sri Lankan consumers.

Commercially important marine fish, yellowfin tuna (YFT), and swordfish (SF), collected from the Indian Ocean around Sri Lanka were analysed for mercury (Hg) and cadmium (Cd) content. The ranges for Hg were < 0.07-1.60 and < 0.07-4.30 mg/kg, while for Cd < 0.006-0.134 and 0.006-0.180 mg/kg in YFT and SF, respectively. In SF 13.3% and in YFT 9.2% exceeded the 1 mg/kg limit for Hg, while 3.1% of YFT exceeded the 0.1 mg/kg limit for Cd. All other samples were well below the maximum limits. Human health risk assessment was investigated using Estimated Daily Intake, Total Hazard Quotient, Hazard Index, and Provisional Tolerable Weekly Intake values for Hg and Cd. The data indicated that the current YFT and SF consumption pattern in Sri Lanka poses no threat to consumer's health. However, further research and awareness on food safety aspects is needed on specific groups such as children and for areas in which consumption of seafood is high.

Total mercury, cadmium and lead levels in main export fish of Sri Lanka.

Total mercury (Hg), cadmium (Cd) and lead (Pb) levels were determined in the muscle of four commercialised exported fish species Thunnus albacares (yellowfin tuna), Xiphias gladius (swordfish), Makaira indica (black marlin) and Lutjanus sp (red snapper) collected from the Indian Ocean, Sri Lanka, during July 2009-March 2010 and measured by atomic absorption spectrophotometry. Results show that swordfish (n = 176) contained the highest total Hg (0.90 ± 0.51 mg/kg) and Cd (0.09 ± 0.13 mg/kg) levels, whereas yellowfin tuna (n = 140) contained the highest Pb levels (0.11 ± 0.16 mg/kg). The lowest total Hg (0.16 ± 0.11 mg/kg), Cd (0.01 ± 0.01 mg/kg) and Pb (0.04 ± 0.04 mg/kg) levels were found in red snapper (n = 28). Black marlin (n = 24) contained moderate levels of total Hg (0.49 ± 0.37), Cd (0.02 ± 0.02) and Pb (0.05 ± 0.05). Even though there are some concerns during certain months of the year, this study demonstrates the safety of main export fish varieties in terms of total Hg, Cd and Pb.

Cadmium, lead and total mercury in Tilapia sp. in Sri Lankan reservoirs.

In 2010, samples of muscles, liver and gills of Tilapia (Oreochromis sp.) were collected from eighteen reservoirs of four districts in Sri Lanka: Anuradapuraya, Polonnaruwa (North Central Province), Hambantota (Southern Province) and Ampara (Eastern Province). Cd, Pb and Hg were determined using atomic absorption spectrometry. Mean Cd, Pb and Hg concentrations in muscle were 0.03 mg/kg, 0.06 mg/kg and 0.26 mg/kg, respectively, while gills contained 0.02 mg/kg, 0.44 mg/kg and 0.36 mg/kg, respectively, on a dry weight basis. The amounts of the three metals in liver were 0.30 mg/kg, 2.07 mg/kg and 0.52 mg/kg on a dry weight basis. The results revealed that the level of heavy metal concentration in Tilapia does not exceed the maximum limit for human consumption according to the European Union and Sri Lankan guidelines.

Total mercury content, weight and length relationship in swordfish (Xiphias gladius) in Sri Lanka.

Mercury (Hg) is a global environmental pollutant that has been the cause of many public health concerns. It is transferred through trophic level and bio magnification in the food chain. Total Hg level was measured by cold vapour atomic absorption spectrometry in muscle tissue of 176 Swordfish (Xiphiasgladius) samples ranging from 11.8-112.0 kg total weight and 45-278 cm total length, collected from major fish landing sites in Sri Lanka during July 2009 to March 2010. Total Hg concentration varied between 0.18-2.58 mg/kg wet weight (ww), with a mean value ± standard deviation of 0.90 ± 0.52 mg/kg ww. Of the investigated samples 32% exceeded Hg limits as set by the European Union and Sri Lankan legislation (1 mg/kg, ww). Hg concentration of swordfish showed a significant positive relationship (P value < 0.05) with the fish length and weight. Consequently, consumption of larger fish leads to an increase in the exposure level for consumers.