This summary information on persistence, biockumulation and toxicity comes from Fass. The risk comes from the Goodpoint report.
Persistence. Lamotrigine is potentially persistent.
Bioaccumulation. Lamotrigine has low potential for bioaccumulation.
Toxicity. Lamotrigine has low chronic toxicity.
Risk. See the Goopoint report.
Fass environmental information
Fass environmental information for Lamictal (lamotrigine) from GlaxoSmithKline (downloaded 2021-04-12).
Persistence: "Ready degradability: <1% degradation in 28 days (TAD 3.11). Inherent degradability: <10% degradation in 28 days (OECD 302). [...] Lamotrigine is not readily degradable or inherently degradable. The phrase “Lamotrigine is potentially persistent” is thus chosen."
Bioaccumulation: Log Dow vid pH 7 = 1.
Toxicity: There are data for 3 trophic levels, most sensitive green algae (Scenedesmus subspicatus) NOEC 7500 mikrog/L.
PEC/PNEC is based on sales data in Sweden in year 2018. PEC/PNEC = 0.0037 which gives the risk insignificant.
Report Goodpoint 2020
Comparative assessment of environmental risk when using antiepileptics: lamotrigine, levetiracetam, oxcarbazepine, topiramate and zonisamide from a Swedish perspective.
Although lamotrigine is linked to a slightly higher risk than other substances (based on higher fat solubility), there is no obvious environmental risk for any of the substances. Therefore, no exchanges from an environmental risk point of view are recommended. Measurements of lamotrigine in Swedish wastewater/biota are recommended.
Author: Health and Medical Care Administration, Region Stockholm