Ecotoxicological effects of atmospheric particulate produced by braking systems on aquatic and edaphic organisms.

Vehicles generate particulate matter (PM) in significant amounts as their brake systems wear. These particles can influence air quality and their transport/deposition may affect the edaphic and aquatic ecosystems. As part of the LOWBRASYS H2020 project, new more eco-friendly brake disc and pad formulations were developed. PMs generated from traditional (FM1-BD1) and innovative (FM4-BD2, FMB-BD7) brake systems in bench tests were studied. The PMs' physical/chemical characteristics were preliminarily investigated. To study the possible environmental impact of the nano-micro particulate, we used a battery of ecotoxicological tests. We employed the microalga Pseudokirchneriella subcapitata, the crustacean Daphnia magna and the bacteria Vibrio fischeri as aquatic bioindicators, while for the edaphic ecosystem we used the seeds of Lepidium sativum and Sorghum saccharatum, the nematode Caenorhabditis elegans, the earthworm Eisenia andrei and the ameba Dictyostelium discoideum. The results showed a higher sensitivity of the freshwater organisms exposed to the soluble PM fraction, with respect to the edaphic ones. FM4-BD2 brake formulation was slightly more toxic for algae (200 mg/L) than FM1-BD1 (500 mg/L). The new system FMB-BD7 particulate was not harmful for crustacean survival, and resulted weakly toxic for algal reproduction only at 500 mg/L. The particulate material per se was found to affect the algal reproduction. No toxic effects were found on nematodes, earthworms and seeds up to 1000 mg/L. However, in D. discoideum the reproduction rate was significantly reduced starting from 100 mg/L; and the lysosomal membrane stability showed a relevant alteration also at minimal concentration (0.1 mg/L). The results demonstrated a minimal risk for biodiversity of the particulates from the different brake systems and highlighted a more eco-friendly performance the new brake-pad FMB-BD7. However, the occurrence of sublethal effects should be considered as a possible contribution of the particle toxicity to the biological effects of the environmental pollution.

Phytotoxicity of wear debris from traditional and innovative brake pads.

Traffic-related emissions include gas and particles that can alter air quality and affect human and environmental health. Limited studies have demonstrated that particulate debris thrown off from brakes are toxic to higher plants. The acute phytotoxicity of brake pad wear debris (BPWD) investigated using cress seeds grown in soil contaminated with increasing concentrations of debris. Two types of pads were used: a commercially available phenol based pad and an innovative cement-based pad developed within of the LIFE+ COBRA project. The results suggested that even through the BPWD generated by the two pads were similar in and morphology, debris from traditional pads were more phytotoxic than that from cementitious pads, causing significant alterations in terms of root elongation and loss of plasma membrane integrity.

Aquatic toxicity of several textile dye formulations: Acute and chronic assays with Daphnia magna and Raphidocelis subcapitata.

Dyes are widely used in various sectors and can be released into the environment where they persist for a long time because of their high stability to light or temperature and their resistance to environmental degradation. Dyes are often poorly characterized and toxicological/ecotoxicological data are available only for a few. These features, coupled with their toxicity, make dyes a possible source of ecological concern, particularly for freshwater aquatic ecosystems. Therefore, new data may be very useful for their risk assessment. In the present study, we investigated the aquatic toxicity of 42 commercial dye formulations using the application of in silico tools and ecological bioassays. The in silico approach was used to assess the similarities among the dyes, highlighting that dyes from the same chemical class are generally similar. No correlation was found among dyes with the same color. Acute and long-term ecotoxicological assays with daphnids and algae were applied to evaluate the potential impact of these products, according to the OECD guidelines 201 and 202. The bioassays were able to identify structures with potential ecotoxicity: only 9 formulations showed toxicity lower than 100mg/L for daphnids while 30 dyes were toxic for algae. In our experimental conditions, algae were more sensitive to dye toxicity, particularly when the effects on cell number were considered.