Impacto do material particulado atmosférico sedimentável emitido por indústrias metalúrgicas em girinos de rã-touro (Aquarana catesbeiana)

Abstract

The settleable particulate matter (SePM), is composed of metals and metalloids which, when deposited in water, can use impacts on the aquatic biota. This study assessed the bioaccumulation of metals, genotoxic and mutagenic effects, as well as physiological and biochemical biomarkers in bullfrog tadpoles (A. catesbeiana), exposed 96 hours to a sublethal and environmentally relevant concentration of SePM (1 g/L-1). The SePM was collected on Ilha do Boi, in Vitória, ES, an area with intense steel and metallurgy activity. The results indicated bioaccumulation of metals in the blood, such as Sn, Cr, La, Ce, Al, Ag, Pb, Ti, and Fe. Health alterations were observed in the animals, with a 25% increase in the hepatosomatic index and a 12% decrease in the condition factor. Hemoglobin concentration and total cell count increased by 17% and 112%, respectively. Mutagenic effects on erythrocytes were indicated by a 340% increase in micronucleus frequency. In the comet assay, there was a significant increase in comet area (44.91%) and DNA content in the tail (85.49%), indicating genotoxic damage. In the heart tissue, high concentrations of Ti, Fe, V, Ba, and Mn were quantified, confirmed bioaccumulation. SePM exposure increased heart rate by 28% and decreased relative ventricular mass by 19%. Cardiac contractility parameters, showed a 60% increase in contraction strength, 50% in contraction rate, 55% in relaxation rate, and 66% in cardiac pumping capacity. The blockage of the NCX exchanger resulted in a significant reduction in the control group and exposed groups, respectively, of 39% and 49% in contraction force, 25% and 4% in contraction rate, 47% and 40% in relaxation rate, and approximately 58% and 64% in cardiac pumping capacity, indicating that the exchanger plays a significant role in calcium cycling. Protein carbonyl levels increased by 80%, the GSH:GSSG ratio increased by 121% and ACAP levels increased by 37% in cardiac tissue. These results indicate that even at a sublethal concentration, SePM demonstrated genotoxic and mutagenic potential, causing alterations in the blood. Additionally, exposure to SePM induce chronotropic, inotropic, and lusitropic responses, as typical compensatory stress responses. The results of oxidative stress biomarkers in cardiac tissue revealed mechanisms and strategies to neutralize reactive oxygen species. This study provides evidence that metallic particles from SePM, originating from metallurgical industries, induce damage and may compromise physiological homeostasis, even with short-term exposure and at sublethal concentrations, reinforcing the need for stricter regulations to control the emission of this material.