The cell transformation assay to assess potential carcinogenic properties of nanoparticles

Single and combined chronic toxicity of cadmium and titanium dioxide nanoparticles in Aquarana catesbeiana (Anura: Ranidae) tadpoles

The rising production and improper disposal of titanium dioxide nanoparticles (TiO2 NPs) into aquatic systems present considerable environmental challenges, especially when these particles interact with other contaminants such as cadmium (Cd). Thus, the current study aimed to evaluate the potential toxic effects on the gills, chondrocranium, body growth, and mortality of Aquarana catesbeiana tadpoles. The tadpoles were exposed to environmentally relevant concentrations of TiO2 NPs (10 µg L-1), and CdCl2 (10 µg L-1), both individually and in combination, for 30 days (chronic exposure), along with a control group. Our results indicate that the co-exposure to TiO2 NPs and Cd induced a higher mortality rate. In the gills, TiO2 NPs led to epithelial simplification, while Cd exposure resulted in stratified epithelium formation. Additionally, there were notable changes in the index of degenerative alterations for the co-exposed group and the overall organ index for the groups exposed to Cd and the mixture. The viscerocranium showed significant malformations in the ceratobranchials and reticular processes, indicating the mixture's toxicological potential during the skeletal system's development. Morphometric analysis also revealed reduced body length and abnormal body ratios in tadpoles from the co-exposure group. In conclusion, TiO2 NPs and Cd, both alone and in combination, exhibit toxicological effects in A. catesbeiana tadpoles, indicating a potential ecological risk associated with releasing these contaminants into aquatic environments.

In vitro cell-transforming potential of secondary polyethylene terephthalate and polylactic acid nanoplastics

Continuous exposure to plastic pollutants may have serious consequences on human health. However, most toxicity assessments focus on non-environmentally relevant particles and rarely investigate long-term effects such as cancer induction. The present study assessed the carcinogenic potential of two secondary nanoplastics: polyethylene terephthalate (PET) particles generated from plastic bottles, and a biodegradable polylactic acid material, as respective examples of environmentally existing particles and new bioplastics. Pristine polystyrene nanoplastics were also included for comparison. A broad concentration range (6.25-200 μg/mL) of each nanoplastic was tested in both the initiation and promotion conditions of the regulatory assessment-accepted in vitro Bhas 42 cell transformation assay. Parallel cultures allowed confirmation of the efficient cellular internalisation of the three nanoplastics. Cell growth was enhanced by polystyrene in the initiation assay, and by PET in both conditions. Moreover, the number of transformed foci was significantly increased only by the highest PET concentration in the promotion assay, which also showed dose-dependency, indicating that nano PET can act as a non-genotoxic tumour promotor. Together, these findings support the carcinogenic risk assessment of nanoplastics and raise concerns regarding whether real-life co-exposure of PET nanoplastics and other environmental pollutants may result in synergistic transformation capacities.