Integrated environmental assessment of iron ore tailings in floodplain soils and plants after the Fundão Dam disaster in Brazil.

Previous studies of the Doce River basin (Brazil) seem to be contradictory regarding the contamination of soils with potentially harmful elements (PHE). This research aimed to perform an integrated assessment of PHE in the soil-plant-tailing system from the area most affected by the iron waste after the Fundão Dam disaster in 2015. Different fractions of PHE (exchangeable, nonexchangeable, reducible, and pseudo-total) were determined on deposited iron waste (DIW), soil waste mixture (SWM), and control soil (CS) samples. Total contents of PHE in Poaceae were also determined, and Allium cepa bioassays were performed to determine DIW and CS cytotoxicity and/or genotoxicity to plants. The Fe and Mn contaminations were the only ones related to the deposition of DIW on floodplains, and other harmful element content (such as As, Hg, Ni, Cd, Cr, and Pb) was not found above baseline values for soils. In addition, a significant part of the Fe and Mn in DIW is readily available or subject to acidification and prolonged flood reduction processes. The high available content of Fe favored its excessive accumulation by Brachiaria. The DIW chemical conditions reduced biological functions of A. cepa under a controlled environment. However, more drastic effects, such as genetic damage, were not seen. The postdisaster action of covering DIW with CS resulted in undesirable enrichment of Pb on the floodplain soils. The integrated results allow the conclusion that the iron waste is not a time bomb for PHE contamination of soils between the Fundão and Risoleta Neves Hydroelectric Dam (~100 km away from Fundão). Integr Environ Assess Manag 2024;20:117-132. © 2023 SETAC.

The potential use of kraft lignins as natural ingredients for cosmetics: Evaluating their photoprotective activity and skin irritation potential.

The cosmetics market has recently undergone changes as consumers increasingly seek sustainable products. In this context, agro-derived lignins have the potential for cosmetics applications. Thus, this study investigated the photoprotective activity and skin irritation potential (OECD TG 439 with SkinVitro-RHE, an in-house reconstructed human epidermis (RHE) model) of a kraft lignin (LE) and two LE-derived lignins modified by enzymatic reactions to achieve higher molecular weight (Mw) (R1: intermediate Mw and E60: highest Mw). Results showed that LE and R1 lignins present adequate photoprotective activity with averages Sun Protection Factor (SPF) of 33.8 ± 0.02 and 22.7 ± 0.04, respectively. The E60 also present adequate SPF (22.4 ± 0.2); however, due to its poor solubility, this lignin has potential application as a physical filter. In terms of safety, these lignins did not cause skin irritation or cellular and structural damage to the epidermis. Additionally, using an analysis based on the autofluorescence feature of lignin, no sign of the tested lignins was found in exposed RHE models, indicating that these three lignins did not penetrate the skin. Altogether, the results indicate a promising application of kraft lignins for sunscreen products regarding safer alternatives and product sustainability. Also, the SkinVitro-RHE showed to be a good model for evaluating the skin irritation potential of substances, including natural cosmetic ingredients.