Avaliação da toxicidade crônica dos contaminantes emergentes diclofenaco resinato e paracetamol frente ao organismo-teste microalga Desmodesmus subspicatus: estudo preliminar

Abstract

Emerging contaminants are formed by an extensive group of chemical substances that mostly do not have maximum values allowed in legislation, but with the potential to cause adverse effects in the environment in which they are present. Pharmaceuticals are increasingly present in the aquatic ecosystem, in cumulative doses that denote concern about chronic toxicity of organisms. Microalgae in the aquatic toxicity evaluation bring answers about contamination and water quality. Because of this fact, this work used the microalgae Desmodesmus subspicatus as a bioindicator specie and evaluated the exposure to oral solutions of diclofenac resinate and paracetamol through chronic toxicity. The D. subspicatus cultivation was performed in CHU medium and the representative calibration curve was generated through a combination of methodologies: cell counting in a Neubauer chamber and spectrophotometric method at a wavelength of 682 nm. The sensitivity test with potassium dichromate, performed to attest the algal batch quality, reached an effective concentration between the values established in the literature. In the chronic tests, for diclofenac resinate the effective mean concentrations were 181.06 ± 11.1 mg. L −1 and 31.47 ± 6.5 mg. L −1 for paracetamol. In the face of worldwide consolidated classifications, diclofenac resinate does not reach values to be considered as highly toxic, on the other hand the concentration of paracetamol is considered dangerous to the aquatic environment. The evaluation of the substances was done in isolation, but it is noteworthy that environmentally other compounds can disturb the aquatic system, potentiating toxic and synergistic effects.