Abstract

ACOSTA DIAZ, Silvia  and  GONZALEZ HERNANDEZ, Francisca. Toxicity of a water-based drilling fluid for use in oil exploration in Cuba. Rev. CENIC Cienc. Quím. [online]. 2024, vol.55, pp. 24-32.  Epub May 07, 2024. ISSN 2221-2442.

To evaluate the damage of oil exploration to ecosystems, ecotoxicological tests are a fundamental tool in environmental risk programs. The products used constitute xenobiotics that can be potentially toxic to soil biota and cause severe metabolic alterations in organisms, which affect structural and functional changes in terrestrial ecosystems. The objective of this research was to carry out a toxicological diagnosis of a water-based drilling fluid for use in oil exploration in Cuba. Toxicological procedures recommended by the Organization for Economic Cooperation and Development (OECD) were used, with two terrestrial contamination bioindicators, earthworms of the species Eisenia andrei and lettuce seeds (Lactuca sativa). The fluid was prepared by making a 1:9 dilutions (sludge: water) (v/v) and the dilutions to be tested were made from the fraction of suspended solids (FSS). As a toxicity criterion, the mean lethal concentration (LC50) was calculated from the mortalities of the bioindicators, with the Statgraphics Centurion XV statistical program, according to the Probit method. The values ​​were compared with the current federal codes (CFR) that classify a toxic fluid when the LC50 is less than 3%. The LC50 for the bioassay with worms was 36.95% and 30.1% for lettuce seeds. According to established criteria, this fluid is non-toxic for the survival of terrestrial biota. These results support the use of this drilling fluid responsibly and with respect to the environment.

Keywords : toxicity; drilling fluids; bioindicators; environment.