Di-n-butyl Phthalate, Butylbenzyl Phthalate and Their Metabolites Induce Haemolysis and Eryptosis in Human Erythrocytes

Phthalates have been extensively used as plasticizers in various fields, including food, cosmetic, and pharmaceutical industry. Those compounds do not form covalent bonds to substances they are being added to, and thus they may migrate easily and penetrate various products used every day. They may reach organisms with air, food, or by a direct skin contact. Significant levels of phthalates and their metabolites are found in urine, breast milk, blood serum, venous blood, and cord blood. The purpose of this study was to assess the simple toxicity (haemolysis) and programmed death (eryptosis) caused by following phthalates: di-n-butyl phthalate (DBP), butylbenzyl phthalate (BBP) and their metabolites: mono-n-butyl phthalate (MBP) and mono-benzyl phthalate (MBzP) in vitro in human RBCs. RBCs were incubated with the above mentioned compounds at concentrations ranging between 0.5 and 500 μg/mL for 24 h. Obtained results demonstrated that DBP and BBP possess higher haemolytic properties compared to their metabolites. The lethal concentration (LC) was determined. The value was 126.37 ± 5.94 μg/mL for DBP, and 103.65 ± 4.03 μg/mL for BBP, and for metabolites the LC value was over 500 μg/mL. All compounds induced eryptosis causing translocation of phosphatidylserine, increased cytosolic calcium ions level, increased caspase-3 and calpain activation in human erythrocytes. BBP caused translocation of phosphatidylserine at a lower concentration compared to DBP. In case of other parameters, more pronounced changes were evoked by DBP at lower concentrations. Metabolites showed a significantly lower toxicity compared to parent compounds.