Assessment of the solubility and bioaccessibility of arsenic in realgar wine using a simulated gastrointestinal system.

Consumption of arsenic (As) wine is a traditional activity during the classic Chinese festival of Duanwu, colloquially known worldwide as the Dragon Boat Day. Arsenic wine is drunk on the morning of the fifth day of the fifth lunar calendar month to commemorate the death of Qu Yuan, a famed Chinese poet who drowned himself in protest of a corrupt government, and to protect against ill fortune. Although realgar minerals are characteristically composed of sparingly soluble tetra-arsenic tetra-sulfides (As(4)S(4)), purity does vary with up to 10% of As being present as non-sulfur bound species, such as arsenate (As(V)) and arsenite (As(III)). Despite, the renewed interest in As speciation and the bioaccessibility of the active As components in realgar based Chinese medicines, little is known about the safety surrounding the cultural practice of drinking As wine. In a series of experiments the speciation and solubility of As in a range of wines were investigated. Furthermore, a simulated gastrointestinal system was employed to predict the impact of digestive processes on As bioavailability. The predominant soluble As species found in all the wines were As(III) and As(V). Based on typical As wine recipes employing 0.1 g realgar mL(-1) wine, the concentration of dissolved As ranged from ca. 100 to 400 mg L(-1) depending on the ethanol content of the preparation: with the As solubility found to be higher in wines with a lower proportion of ethanol. Based on a common 100 mL measure of wine with a concentration of 400 mg As L(-1), the amount of soluble As would equate to around half of the acute minimal lethal dose for adults. This is likely an underestimate of the bioaccessible concentration, as a three-fold increase in bioaccessibility could be observed in the intestinal phase based on the results from the stimulated gastrointestinal system.