This summary information comes from Fass, see details below.
Persistence. Hydroxychloroquine is potentially persistent.
Bioaccumulation. Hydroxychloroquine has low potential to bioaccumulate.
Toxicity. Hydroxychloroquine has high chronic toxicity.
Risk. The use of hydroxychloroquine (sales data Sweden 2018) gives the risk insignificant.
Fass environmental information for Plaquenil (hydroxychloroquine) from Sanofi AB (downloaded 2020-04-03).
Persistence: "Test showed 0% degradation in 28 days. Hydroxychloroquine is therefore potentially persistent."
Bioaccumulation: "Log D (pH 7.4) = 0.62 (method: experimentally obtained by Sirius GLpK automated computerized potentiometric system). Since log D is < 4 at pH 7.4, the substance has low potential for bioaccumulation."
Chronic toxicity: There are data for 3 trophic levels, most sensitive crustacean (Daphnia magna) NOEC 21 days (reproduction): 85.8 microg/L.
PEC/PNEC is based on sales data in Sweden in year 2018. PEC/PNEC = 0.0565 which gives the risk insignificant.
Author: Health and Medical Care Administration, Region Stockholm