Underlying data for P, B, T and risk are from Fass.se.
Diphenhydramine has been detected in treated wastewater, surface water and fish in Stockholm County in the last five years (2012–2016).
Fass environmental information for Desentol (diphenhydramine) (downloaded 2018-07-06).
Persistence: No data.
Bioaccumulation: Log P of 3.27.
Toxicity: No data.
Sales data for Sweden is available for 2015. PEC = 0.000872 microg/L. "According to the European Medicines Agency guideline on environmental risk assessment of medicinal products (EMA/CHMP/SWP/4447/00), use of diphenhydramine is unlikely to represent a risk for the environment, because the predicted environmental concentration (PEC) is below the action limit 0,01 μg/L."
Author: The Pharmaceutical unit of Region Stockholm