Hair dyes are widely used cosmetic products that can contain trace metals and metalloids, posing potential health risks through dermal exposure. This study aimed to assess and compare the concentrations of selected metals and metalloids in six brands of commercial hair dyes sold in Brazil and Paraguay and to evaluate their average daily dermal exposure doses, hazard quotients, hazard indices, and carcinogenic risk. Concentrations of Cr, Cd, Co, Cu, Fe, Mn, Mo, Ni, As, Al, Pb, Ba, Ag, and Zn in hair dye were quantified by standardized analytical methods. The Paraguayan brand showed the highest levels for several elements, including As (4.17 mg/kg), Al (130.276 mg/kg), and Fe (30.033 mg/kg). Estimated dermal exposure doses reached up to 3.35 × 10⁻⁶ mg/kg/day for arsenic, 1.68 × 10⁻³ mg/kg/day for aluminum, and 8.59 × 10⁻⁸ mg/kg/day for chromium. Although all hazard indices remained below 1, suggesting low non-carcinogenic risk, the calculated carcinogenic risk for arsenic in the Paraguayan product was 1.23 × 10⁻⁵, entering the medium-risk range. These findings highlight relevant differences in raw material control and potential cumulative health risks, especially for frequent users. Continuous quality control, harmonized regulatory standards, clear labeling, and further biomonitoring studies are strongly recommended to minimize long-term exposure to toxic elements in hair dye formulations and to ensure safer consumer products.

Urban and peri-urban river systems subjected to intensive agriculture are vulnerable to diffuse metal(loid) inputs, yet the integration of hydrological compartments, bioindicators, and human health risk remains poorly explored. This study investigated the seasonal dynamics, bioaccumulation patterns, and potential human health risks associated with metal(loid)s in the Santa Virgem River (Brazil–Paraguay border), using water from backwater zones and three plant groups (Apiaceae angiosperms, mosses, and the liverwort Dumortiera sp.). Water and plant samples were collected during five seasonal campaigns (2019–2020) and analyzed by ICP OES. Multivariate analysis (PCA) was applied, and biological accumulation coefficients (BAC) and chronic daily intake (CDI) were estimated for adults and children under different ingestion scenarios. Results showed that Mg, Fe, K, S, and P dominated water chemistry, while As, Cd, Cr, Cu, Pb, and Se were mostly below detection limits. PCA explained 77.6% of total variance, distinguishing agricultural and hydrological phases. Bryophytes exhibited markedly higher BAC values, particularly for Mn (up to 2.3 × 10⁵) and Fe, compared with Apiaceae. CDI and hazard assessment indicated negligible non-carcinogenic risk for most elements (HQ < 1), except phosphorus, which dominated the Hazard Index due to its low reference dose. Overall, the results demonstrate that hydrodynamic conditions and plant functional traits jointly control metal(loid) dynamics, highlighting the value of multispecies biomonitoring in peri-urban river systems.

Kalanchoe laetivirens is widely consumed as a medicinal plant in rural and urban communities, traditionally used in folk medicine for treating inflammatory conditions and cancer. However, little is known about its elemental composition and the potential health risks associated with different preparation methods. This study aimed to evaluate concentrations of Al, As, Ba, Co, Cu, Fe, Mg, Mn, Mo, Na, Ni, P, Pb, Se, V, and Zn in raw leaves, tea infusions, and aqueous extracts, and to assess associated health risks. Elemental analysis revealed significant differences among preparations, with raw leaves presenting the highest concentrations, tea showing intermediate values, and aqueous extracts the lowest. For example, potassium (K) reached 15,399.31 ± 131.55 mg/kg in leaves and 12,249.97 ± 240.17 mg/L in tea, while arsenic (As) and lead (Pb) were also detected at concerning levels, with As at 5.98 ± 1.64 mg/L and Pb at 3.82 ± 0.179 mg/L in tea. Risk assessment was performed using the Chronic Daily Intake (CDI), Hazard Quotients (HQs), Hazard Index (HI), and Incremental Lifetime Cancer Risk (ILCR), considering different exposure frequencies. Results indicated phosphorus (P) as the dominant contributor to non-carcinogenic risk, with HI values exceeding safety thresholds in all scenarios, while arsenic was the primary carcinogenic element, with ILCR values up to 10⁻³ in tea. These findings highlight the influence of preparation methods on exposure levels and reinforce the need for continuous monitoring and regulatory guidelines to ensure the safe medicinal use of K. laetivirens.