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<p>High levels of arsenic (As) in soils pose a significant threat to both human health and the environment. Therefore, monitoring soil quality based on established guidelines is essential. Current environmental risk assessment methods, which mainly involve plants, consider macroscopic parameters under controlled conditions, such as in greenhouses. However, these methods do not account for genotoxic effects at the cellular level. In this context, a study was conducted to assess the toxicity of tropical soils contaminated with As. The approach involved monitoring the early growth of model seedlings in microplates and establishing preventive values, including mutagenic effects on DNA. For this purpose, seeds of sensitive species were exposed for 120&#xa0;h in microplates to two tropical soils (Oxisol and Inceptisol) and a Tropical Artificial Soil (TAS), each spiked with increasing concentrations of As (0, 8, 14.5, 26, 46.5, 84, 150, and 270&#xa0;mg kg⁻¹). After exposure, the germination percentage, germination speed index, root and shoot lengths, and fresh biomass of all species were assessed. Furthermore, microscopic analyses for the detection of chromosomal aberrations and nuclear alterations were conducted exclusively in <i>Allium cepa</i>. Based on these data, effective concentrations of 25% (EC₂₅) and 50% (EC₅₀) were determined. <i>Lactuca sativa</i> and <i>A. cepa</i> were the most susceptible species in macroscopic responses, with the greatest effects observed in TAS. For <i>L. sativa</i>, EC₅₀ values were 40.10&#xa0;mg As kg⁻¹ (root) and for <i>A. cepa</i>, 26.97&#xa0;mg As kg⁻¹ (shoot). In meristematic cells of <i>A. cepa</i>, As exposure induced chromosomal abnormalities (EC₅₀ = 12.30&#xa0;mg As kg⁻¹ in TAS), micronucleus formation (13.80&#xa0;mg As kg⁻¹ in Oxisol), and a reduction in the mitotic index (11.57&#xa0;mg As kg⁻¹ in Oxisol). Based on the EC₅₀ values, a species sensitivity distribution (SSD) curve was constructed, from which the hazardous concentration for 5% of species (HC₅) was estimated at 22&#xa0;mg As kg⁻¹. This value is close to the Prevention Value established for As in the State of Minas Gerais, Brazil, reinforcing the soundness of the microplate-based methodology and highlighting the importance of including microscopic parameters in ecotoxicological assessments. Therefore, this study demonstrates the relevance of cell cycle-related variables as valuable tools for ecotoxicological monitoring of arsenic in tropical soils.</p>

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Eco(geno)toxicologic effects of arsenic-contaminated tropical soils: plant bioassays via the microplate approach

  • 期刊论文

  • 发表日期：

    2025年10月3日

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  • Ingrid Fernanda Santana Alvarenga,
  • Graciele Lurdes Silveira,
  • Guilherme Henrique Silva,
  • Gabriel Caixeta Martins,
  • Leonardo Mendes da Silva,
  • Luiz Roberto Guimarães Guilherme,
  • Larissa Fonseca Andrade-Vieira

摘要

High levels of arsenic (As) in soils pose a significant threat to both human health and the environment. Therefore, monitoring soil quality based on established guidelines is essential. Current environmental risk assessment methods, which mainly involve plants, consider macroscopic parameters under controlled conditions, such as in greenhouses. However, these methods do not account for genotoxic effects at the cellular level. In this context, a study was conducted to assess the toxicity of tropical soils contaminated with As. The approach involved monitoring the early growth of model seedlings in microplates and establishing preventive values, including mutagenic effects on DNA. For this purpose, seeds of sensitive species were exposed for 120 h in microplates to two tropical soils (Oxisol and Inceptisol) and a Tropical Artificial Soil (TAS), each spiked with increasing concentrations of As (0, 8, 14.5, 26, 46.5, 84, 150, and 270 mg kg⁻¹). After exposure, the germination percentage, germination speed index, root and shoot lengths, and fresh biomass of all species were assessed. Furthermore, microscopic analyses for the detection of chromosomal aberrations and nuclear alterations were conducted exclusively in Allium cepa. Based on these data, effective concentrations of 25% (EC₂₅) and 50% (EC₅₀) were determined. Lactuca sativa and A. cepa were the most susceptible species in macroscopic responses, with the greatest effects observed in TAS. For L. sativa, EC₅₀ values were 40.10 mg As kg⁻¹ (root) and for A. cepa, 26.97 mg As kg⁻¹ (shoot). In meristematic cells of A. cepa, As exposure induced chromosomal abnormalities (EC₅₀ = 12.30 mg As kg⁻¹ in TAS), micronucleus formation (13.80 mg As kg⁻¹ in Oxisol), and a reduction in the mitotic index (11.57 mg As kg⁻¹ in Oxisol). Based on the EC₅₀ values, a species sensitivity distribution (SSD) curve was constructed, from which the hazardous concentration for 5% of species (HC₅) was estimated at 22 mg As kg⁻¹. This value is close to the Prevention Value established for As in the State of Minas Gerais, Brazil, reinforcing the soundness of the microplate-based methodology and highlighting the importance of including microscopic parameters in ecotoxicological assessments. Therefore, this study demonstrates the relevance of cell cycle-related variables as valuable tools for ecotoxicological monitoring of arsenic in tropical soils.