Seafood, such as marine fish, crustaceans, bivalves, and algae, is a rich source of protein, vitamins, minerals, and polyunsaturated fatty acids. It forms a crucial part of many dietary patterns in the world1–3 and can help prevent chronic diseases, improve glycemic control, enhance the immune system, and sustain proper brain function in humans4. Several dietary recommendations recommend at least two servings of fish and seafood per week to gain essential nutrients, promote neurodevelopment in children, and prevent coronary heart disease2. Despite the significant health benefits, seafood consumption can also lead to health problems due to the presence of toxic metals and persistent organic pollutants (POPs)5.
Metals are typically categorized as essential, probably essential, and non-essential. Copper(Cu), zinc(Zn), iron(Fe), and selenium(Se) are nutritionally crucial elements that play a significant role in human metabolism. Although nickel(Ni) and vanadium(V) are not essential to human health, they may be beneficial at low exposure levels. Arsenic (As), mercury (Hg), chromium (Cr), cadmium (Cd), and lead (Pb) have no nutritional value at low concentrations and may be harmful. Furthermore, both essential and probably essential elements can cause toxic effects at high concentrations5–7.
Studies have shown various degrees of heavy metal pollution in the seafood from many coastal areas due to rapid industrialization and urbanization8. Trace metals in aquatic environments can accumulate in marine organisms and be transferred to humans via the food chain9. Many coastal marine environments in China have been affected by metal contamination, which is influenced by environmental conditions, pollution sources, and economic development10. Heavy metals, such as As, Cd, Cr, and Pb from natural and anthropogenic sources may continuously enter marine environments in recent years11. Since heavy metals are non-biodegradable and persistent contaminants in the aquatic environment, they can easily accumulate in marine organisms12. These heavy metals are transferred to humans upon consumption, posing severe health hazards by adversely affecting the brain, the central nervous system, the cardiovascular system, the kidneys, the reproductive system, and the immune system13. Besides non-cancerous effects, certain metals (e.g., As, Cd, Pb, and Hg) also cause mutations, teratogenic effects, and carcinogenic outcomes in living organisms14. The health risk of heavy metals contamination is a growing global concern, and various studies have focused on human exposure due to contaminated seafood consumption15,16.
The consumption of heavy metals can have both carcinogenic and non-carcinogenic impacts on human health. In order to assess the potential health hazards linked to prolonged ingestion of chemical contaminants in food, the United States Environmental Protection Agency (USEPA) has devised the Target Hazard Quotient (THQ) and Combined THQ (CTHQ) for quantitative evaluation. Carcinogenic metals are associated with cancer slope factors (CSF) to estimate lifetime target cancer risks (TR). A THQ below 1 generally poses no obvious risk to humans, while a value equal to or greater than 1 indicates a potential health risk. Previous studies have confirmed the validity of these methods in assessing the risk to human health17–19. This study applies these techniques to estimate the health risks associated with seafood consumption. Analyzing the concentrations of multiple heavy metals in different seafood species and comprehending their ecological implications are crucial for safeguarding marine ecosystems.
Located on the mainland of southern China, Hainan Island is the second largest island in the country. Previous studies have shown that As, Pb, Cd, Cu, and Cr concentrations were 10.3 mg/kg dw, 23 mg/kg dw, 0.1 mg/kg dw, 25 mg/kg dw, and 140 mg/kg dw, respectively, in coastal sediments20. The popularity of Hainan as a tourist destination has gradually increased since the construction of the Hainan International Tourism Island and Hainan Free Trade Port. Haikou City, located at the northernmost tip of Hainan Island, is the capital city of Hainan Province and offers an abundance of marine products. Haikou's industrial economy has experienced steady growth in recent years. Furthermore, Haikou's seafood is not only consumed locally but also distributed to other provinces within China and exported to international markets.21. Previous studies have evaluated the metal concentrations,daily consumption (DC) and potential health risks in fish in Haikou22,23. However, crustaceans and bivalves were more likely to accumulating heavy metals, which live in the lower areas of the habitat (i.e., sediment). At present, limited knowledge is available for crustaceans, bivalve and alga heavy metal levels in the area. Therefore, the toxic heavy metal (As, Cd, Cr, and Pb) content in different kinds of four commonly consumed seafood (fish,crustaceans, bivalve and alga) from Haikou markets were compared, and the possible health risks associated with dietary heavy metal exposure were evaluated. The results could help understand the current situation regarding heavy metals pollution and aid the development of targeted response measures to preserve marine ecosystems and protect public health.