A study published on July 2, 2026, in the journal New Contaminants tested five pharmaceuticals on the brine shrimp Artemia salina. The research evaluated hydroxychloroquine, ivermectin, nitazoxanide, loratadine, and betamethasone.

In 48-hour acute toxicity tests, hydroxychloroquine showed no toxic effect on Artemia salina at the tested concentrations. Ivermectin, betamethasone, loratadine, and nitazoxanide caused mortality in the shrimp. The study ranked the drugs by toxicity as follows: ivermectin, followed by betamethasone, then loratadine, nitazoxanide, and hydroxychloroquine. Ivermectin was the most toxic compound tested, with mortality exceeding 50% at all tested concentrations.

The lowest observed effect concentration was 1.0 μg/L for ivermectin. For betamethasone, the lowest observed effect concentration was 4 μg/L. Loratadine's lowest observed effect concentration was 0.02 mg/L, and for nitazoxanide, it was 0.05 mg/L.

"Our results show that some drugs used or promoted during COVID-19 may affect marine organisms and deserve closer environmental monitoring," said Denis Moledo de Souza Abessa, a corresponding author of the study. The study calls for more research on the occurrence, persistence, bioaccumulation, and chronic toxicity of COVID-19 related drugs in marine environments. Researchers also called for improved wastewater treatment and public awareness to reduce pharmaceutical pollution.

Study Scope

The research focused on pharmaceuticals that were widely used or discussed during the COVID-19 pandemic. The findings indicate a need for environmental monitoring of these substances to understand their impact on marine ecosystems. The call for improved wastewater treatment and public awareness aims to reduce the entry of these compounds into aquatic environments.