According to the Swedish Medicines Agency's Summary of Product Characteristics for Soolantra cream, ivermectin is highly toxic to invertebrates and a risk has been identified for water, sediment and soil. Caution should be exercised to prevent environmental exposure, especially exposure to aquatic environments. Bioaccumulation studies are ongoing.
Environmental information for the substance is not available on fass.se. It is voluntary for manufacturers to publish environmental impact information on fass.se.
Comparative assessment of environmental risk and risk of resistance selection in human use of ivermectin, metronidazole, lymecycline and azelaic acid in Sweden.
The risk is clearly highest for lymecycline based on measured concentrations of tetracycline in uncleaned waste water that exceeds experimental established selective levels for antibiotic resistance in bacteria. A similar but lower risk profile exists for metronidazole based on total use but with significantly lower empirical support for the efficacy The topical use of metronidazole results in a negligible risk of resistance selection in waste water treatment plants. The risk of effects of human use of ivermectin is also low, given an expected contribution to exposure in aquatic environments at subnanogram levels, and a majority of efficacy studies that show significantly higher levels of efficacy. Since there is (at least) a study that reports effects at 1 pg/L, however, one can not completely rule out risk. For azelaic acid there is nothing that indicates an environmental hazard.
Author: Health and Medical Care Administration, Region Stockholm