Etonogestrel is a molecule used in hormonal contraceptives, most notably the subdermal implant Implanon. [Wikipedia]
The T-value in the score for hazard refers to chronic toxicity. Underlying data for P, B, T and risk comes from Fass.se, see below. Measurements of etonogestrel in the environment are lacking.Etonogestrel is the active metabolite of desogestrel. Etonogestrel has approximately the same ability to bind to the androgen receptor in fish such 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. Below is Hazard and Risk from Fass environmental information for Nexplanon (etonogestrel) (downloaded 2018-07-02) Hazard Persistence: "Sediment Transformation (OECD 308) (Ref. XII): DT50 in water: 10-11 days; DT50 in sediment: 35-70 days; DT50 in total system: 9.2-50 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 183 days for fish (Oryzias latipes) 2.7 nanog/L. Risk PEC/PNEC is based on sales data in Sweden in year 2015. PEC/PNEC = 3.1 which gives the risk moderate.
Runnalls TJ, Beresford N, Losty E, Scott AP, Sumpter JP. Several synthetic progestins with different potencies adversely affect reproduction of fish. Environ Sci Technol. 2013;47:2077-84.
Ellestad LE, Cardon M, Chambers IG, Farmer JL, Hartig P, Stevens K et al. Environmental gestagens activate fathead minnow (Pimephales promelas) nuclear progesterone and androgen receptors in vitro. Environ Sci Technol. 2014;48:8179-87.
Bain PA, Kumar A, Ogino Y, Iguchi T. Nortestosterone-derived synthetic progestogens do not activate the progestogen receptor of Murray-Darling rainbowfish (Melanotaenia fluviatilis) but are potent agonists of androgen receptors alpha and beta. Aquat Toxicol. 2015;163:97-101.