With regard to the sustainability of plastics, the role of plastic additives can no longer be ignored or underestimated, as additives may play a more significant role in the biological impact of plastics than anticipated. Plasticizers form the largest group of additives, and phthalates are the best-known plasticizers. To date, several low molecular weight phthalates are restricted/banned due to health and environmental hazards, so various substitute plasticizers, especially high molecular weight phthalates such as di(2-propylheptyl) phthalate (DPHP), in particular, are increasingly used. However, the hazard data of DPHP, particularly those for environmental organisms, are very limited. The current study investigated the potential long-term impact of substitute plasticizer DPHP in comparison to that of the previously dominant di(2-ethylhexyl) phthalate (DEHP). As model organisms, aquatic arthropods, such as crustacean Daphnia magna, and terrestrial arthropods, such as mealworm Tenebrio molitor and woodlice Porcellio scaber, were chosen. Exposure to phthalates was carried out via 0.5–1000 mg DPHP/DEHP/kg-spiked sediment, soil, or food, depending on the assay. Solvents were used in spiking, and results are presented in relation to the solvent controls. For D. magna, both phthalates induced delayed reproduction in F0 and F1 generations and a smaller parental size at 25 mg/kg. The reduced number of broods (DPHP) and fertility (DEHP) was recorded in the F1 generation. For T. molitor, no adverse effects on organism mass, moult, or development were recorded during 8 week exposure at up to 1000 mg/kg food. For P. scaber, a 2-week exposure to phthalates did not affect immunity but triggered biochemical responses. DEHP exposure induced potential neurotoxicity (increase in acetylcholinesterase) above 50 mg/kg and detoxification (increase in glutathione S-transferase) above 100 mg/kg, simultaneously reducing metabolic activity. DPHP induced detoxification processes, even at 5 mg/kg. In conclusion, DPHP toxicity induction potential was comparable to that of DEHP, indicating that more hazard data are needed to ensure that DPHP is not a regrettable substitution to DEHP.
Kokalj et al. (Sun,) studied this question.