A global review on perfluoroalkyl acids (PFAAs) in the riverine systems: Environmental behaviours and risks implications

This review provides a comprehensive global overview of the occurrences, distribution, emissions, and associated risks of perfluoroalkyl acids (PFAAs) in riverine systems across both developed and developing countries including the United States (US), Spain, France, Netherlands, Germany, Pakistan, China, Korea, Vietnam, Italy, and Japan. Data for this review were systematically gathered through a comprehensive and structured search process using various databases, search engines, and academic repositories to identify relevant literature and studies. Human health risks were assessed using recommended United States Environmental Protection Agency (USEPA) models, including estimated daily intake (EDI), hazard risk (HR), and hazard index (HI) for each reported PFAA compound in the studied countries. The overall results revealed significant variability in PFAAs contamination from the 1950s to 2023, reflecting extensive industrial usage and increasing environmental concerns, with levels often exceeding the permissible limits set by environmental quality standards established by national or international regulatory authorities, agencies, and organizations. Among the studied countries, Italy exhibited the highest average sum of PFAA compounds (∑PFAAs) concentration in riverine water, ranging from 4.07 to 140.61 ng/L, with an average of 41.37 ng/L, followed by the Netherlands, China, Japan, the US, Pakistan, Spain, France, Germany, Korea, and Vietnam. Similarly, Germany showed the highest average ∑PFAAs concentration in riverine sediments, ranging from 40.25 to 213.00 ng/g, with an average of 126.63 ng/g, followed by China, Spain, the US, Pakistan, Vietnam, and Korea. Whereas, in riverine fish, Spain had the highest average ∑PFAAs concentration, ranging from 0.05 to 144.97 ng/g, with a mean of 15.94 ng/g, followed by Korea, Vietnam, and the US. From a human risk perspective, the highest average EDI of ∑PFAAs via riverine water consumption was observed in the dependent population of Italy (2.02 × 10^-3 ng/L/day), followed by the Netherlands (8.24 × 10^-4 ng/L/day), the US (5.56 × 10^-4 ng/L/day), Pakistan (3.99 × 10^-4 ng/L/day), Japan (3.69 × 10^-4 ng/L/day), France (3.42 × 10^-4 ng/L/day), China (2.58 × 10^-4 ng/L/day), Spain (2.43 × 10^-4 ng/L/day), Germany (1.17 × 10^-4 ng/L/day), Korea (6.01 × 10^-5 ng/L/day), and Vietnam (1.28 × 10^-5 ng/L/day). For fish consumption, Spain recorded the highest average EDI of ∑PFAAs (9.92 × 10⁰ ng/g/day) in its dependent population, followed by the US (3.44 × 10⁰ ng/g/day), Korea (8.13 × 10^-1 ng/g/day), and Vietnam (4.99 × 10^-1 ng/g/day). The non-carcinogenic HR values for individual PFAA compounds via riverine water intake in the dependent populations of both developed and developing countries were within acceptable limits (<1). However, the HI values for ∑PFAAs intake via riverine fish consumption in the dependent population exceeded the threshold (>1) in the developed countries, the US and Spain, indicating higher potential risks associated with fish consumption in these countries. Given the inadequate wastewater treatment facilities in many regions, coupled with untreated runoff from urban areas and agricultural fields draining directly into rivers, this study underscores the urgent need for integrated prevention and control measures to mitigate PFAAs contamination in riverine systems and reduce associated risks. Ultimately, stricter regulations, improved monitoring, and enhanced water treatment technologies are crucial to reducing PFAAs contamination and safeguarding public health.