Mercury (Hg) in bottled water from different countries: determination at nanogram/sub-ng per liter levels and human health risk assessment

Mercury (Hg) is a naturally occurring toxic element found worldwide, released from both natural and anthropogenic sources. Its long lifetime allows for complex transformations, deposition, and potential impact on uncontaminated areas. Methylmercury, known for its heightened toxicity, is predominantly acquired by humans through the consumption of fish and seafood, whereas the intake of inorganic mercury from drinking water and non-alcoholic beverages is comparatively minimal. The global consumption of bottled waters (BW) is rising annually, with a significant portion of the population relying on them. Despite numerous publications on heavy metals in BW, mercury determination often lacks the sensitivity required for ultratrace levels. Few surveys at regional and national scales have studied Hg at nanogram/sub-nanogram per liter levels and conducted human health risk assessments for long-term exposure. To address these gaps, we analyzed thirty-four bottled water samples from twelve countries (Croatia, France, Germany, Italy, Morocco, Norway, Poland, Serbia, Slovenia, Switzerland, Turkey, United Kingdom). Samples were processed in a dedicated clean room facility, and total mercury analyses were conducted using a modified US-EPA 1631 method with Cold Vapor Atomic Fluorescence Spectrometry-CVAFS (MercurPlus, Analytik Jena). Validation included certified reference materials, different Hg standard solutions, and recovery checks through matrix spikes and duplicates. Hg concentrations within the ng/sub-ng per liter range form the basis for a comprehensive health risk assessment. Adherence to national/international standards for bottled waters, typically with total mercury concentration threshold below 1 or 2 μg/L ensures public health safety and, through the provision of preliminary data, enhances our understanding of mercury levels, facilitating an accurate assessment of potential health risks associated with consumption.