Desogestrel is converted in the body into the active metabolite etonogestrel. Environmental data from Fass refer to etonogestrel.
This summary information comes from Fass. See also the report from Goodpoint.
Persistence. Desogestrel is slowly degraded in the environment.
Bioaccumulation. Desogestrel has low potential for bioaccumulation.
Toxicity. Desogestrel has very high chronic toxicity.
Risk. The use of desogestrel (sales data Sweden 2018) has been considered to result in moderate environmental risk.
Fass environmental information for Cerazette (desogestrel) from MSD (downloaded 2021-07-06).
Persistence: "Sediment Transformation (OECD 308): DT50 (total system) = 9.2 to 50 days."
Bioaccumulation: "Log Kow = 3.5. Bioaccumulation (OECD 305): Flow through study with Bluegill sunfish (Lepomis macrochirus) Lipid normalized kinetic BCF = 128."
Chronic toxicity: There is NOEC for 3 trophic levels, lowest NOEC for fish (Oryzias latipes) 2.7 nanog/L.
PEC/PNEC is based on sales data in Sweden in year 2018. PEC/PNEC = 2 which gives the risk moderate.
A comparison of desogestrel and etonogestrel. Etonogestrel has approximately the same ability to bind to the androgen receptor in fish as levonorgestrel. A substance's ability to activate the androgen receptor in fish is believed to contribute to increased risk of environmental impact. Etonogestrel also binds to SHBG (Sex Hormone Binding Globulin). Binding to SHBG is believed to contribute to increased bioconcentration (and thus potency) in fish. Based on this, it can be assumed that there is a risk associated with the use of etonogestrel/desogestrel and that these substances appear additive with other androgenic gestagens in the environment.
Therefore, there is no clear environmental reason to choose etonogestrel before desogestrel or vice versa.
Author: Health and Medical Care Administration, Region Stockholm