Impact of polyaluminum chloride on the bioaccumulation of selected elements in the tissues of invasive spiny-cheek crayfish (Faxonius limosus) - Potential risks to consumers.

The effect of coagulants used in lake reclamation on crayfish is poorly understood. Therefore, the aim of this study was to evaluate changes in the bioaccumulation of Al, Ca, Cu, Fe, K, Mg, Na and Zn in the gills, exoskeleton, muscle and hepatopancreas of spiny-cheek crayfish (Faxonius limosus) as a result of exposure to PAX®18 coagulant, containing polyaluminum chloride. The study also evaluated the risk to human health from the consumption of crayfish muscle. Metal levels, determined using atomic absorption spectrometry, differed between metals (the highest concentrations for Ca, K, Na, Mg) and the body part. Calcium was most abundant in the exoskeleton, K in the muscles, while Cu and Al in the hepatopancreas. The bioaccumulation of metals was affected by exposure to the coagulant, with a statistically significant (p < 0.05) increase in muscle concentration of Al and Na and a decrease in Ca and Fe. The concentrations of elements (in μg g) in the muscle of the control group crayfish and those in contact with the coagulant were, respectively: K (2150; 2090), Na (1540; 2020), Ca (749; 602), Mg (207; 174), Al (103; 164), Zn (21.1; 19.1), Fe (7.6; 3.8) and Cu (8.4; 7.6). Most elements were below 12% of the Dietary Reference Values (DRV). The Al concentration in the muscle exceeded the tolerable weekly intake (TWI) (maximum 164% TWI for muscle of crayfish exposed to polyaluminum chloride). In conclusion, the studied F. limosus had typical elemental bioaccumulation for a crayfish, but the contact with the coagulant increased Al concentration and decreased Fe, Ca, Mg, Zn and Cu concentrations. The muscle of crayfish can be used as a supplementary source of essential elements in the human diet, but it seems necessary to introduce obligatory control of Al levels due to the use of polyaluminum chloride in lake restoration.