Toxic risk evaluation of effluents from a swine biodigester in the plant models Lactuca sativa and Allium cepa.

Pig farming is recognized as an activity with great polluting potential. The aim was to investigate possible environmental risks of effluents from the stabilization pond (SP) and the raw effluent (RE) from the biodigestion process of swine residues, in different concentrations in the models Lactuca sativa and Allium cepa. Seeds were germinated in different dilutions, 100% (C1), 50% (C2), 25% (C3), 12.5% (C4), 6.25% (C5), 3.12% (C6), 0.78% (C7), and 0.39% (C8). Distilled water was used as the negative control (CN) and trifluralin (0.84 g/L-1) as the positive control. Germination (GR), root growth (RG), cell cycle, and oxidative stress (OS) were analyzed. To assess OS, the activity of the enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) and the quantification of glutathione (GSH) and lipid peroxidation (LPO) were analyzed. Data were submitted to ANOVA (one way), followed by the Kruskal-Wallis mean test (P ≤ 0.05). Chemical analysis showed high values of Cu, Fe, Mn, and Zn. Dilutions (C1, C2, C3 RE) and (C1 and C2 SP) inhibited GR and RG of L. sativa and A. cepa than other concentrations. The mitotic index showed a reduction in C5 (RE), C6, and C7 (SP) of L. sativa and C3 and C4 (SP) of A. cepa in relation to CN and higher frequencies of chromosomal alterations. Regarding the OS, only the concentrations of SP treatment showed statistical difference in relation to the NC: in L. sativa model, GSH at (C5 and C8) concentrations and LPO (C7); in A. cepa model, SOD (C3 and C4), GST (C4, C5 and C6), GSH (C5 and C8), and CAT (C3 and C7). The alterations in metabolism are possibly related to the metals, such as zinc and copper, observed in high amounts in the raw waste. The results allowed us to conclude that the raw and stabilization pond effluents offer environmental risks, requiring caution and monitoring in the use of these effluents.

Toxicogenetic, biochemical, and anatomical effects of the herbicide Clethodim on Allium cepa L.

Pesticides are compounds with several chemical or biological agents developed to potentiate the biocide action. Their use is associated with increased economic and agricultural productivity worldwide but can harm health and the environment, damaging existing biota. Clethodim is a systemic post-emergent herbicide for grasses, highly selective for cotton, coffee, onions, carrots, soybeans, etc. Therefore, this work aimed to evaluate the harmful effect of the herbicide Clethodim with the model plant Allium cepa. A series of tests were conducted to evaluate the effects of the herbicide under study. Germination tests, root growth, cell, and nucleolar cycle analysis, as well as oxidative stress assessment and histological analysis of the roots, were performed. The results indicated that the herbicide demonstrated phytotoxicity, inhibiting germination at C1 (1.92 g/L) and C3 (0.84 g/L), and root growth at all concentrations, presenting mutagenicity at C1 (1.92 g/L) and C4 (0.24 g/L), evidenced by the increased frequency of micronuclei. In addition, changes were observed in the enzymatic activity of the enzymes catalase at concentrations C1 (1.92 g/L) and C2 (0.96 g/L) and ascorbate peroxidase at concentrations C1 (1.92 g/L), C2 (0. 96 g/L), and C3 (0.48 g/L) and in cell elongation at concentrations C1 (1.92 g/L) and C3 (0.48 g/L), demonstrated in histological analyses of the root apex.