This summary information comes from Fass.
Persistence. The potential for persistence of timolol cannot be excluded, due to lack of data.
Bioaccumulation. Timolol has low potential for bioaccumulation.
Toxicity. No data.
Risk. Risk of environmental impact of timolol cannot be excluded, due to the lack of environmental toxicity data.
Since 2006, an Environmental Risk Assessment (ERA) for the active pharmaceutical substance shall accompany an application for a marketing authorisation in EU for a medicinal product for human use. Parts of environmental data can be found in the public investigation report (PAR/EPAR for medicinal product through a centralized procedure). Since the benefit/risk assessment for human medicinal products at present does not include environmental effects, an update of the environmental risk assessment is not required for renewals of marketing authorizations. There is thus no requirement for companies to stay informed about the development of their substances from an environmental point of view and consequently to update the environmental risk assessment as new data are published.
"The PECsurfacewater values from the Phase I exposure assessment of bimatoprost and timolol were calculated to 8.4 x 10-6 and 1.4 x 10-5 μg/L, which is significantly less than the action limit of 0.01 μg/L described in the draft guideline “Guideline on the Environmental Risk Assessment of Medicinal products for Human use”. Ganfort is unlikely to pose a risk to the environment."
Fass environmental information for timolol from Azarga (brinzolamide, timolol) (downloaded 2021-01-19).
Persistence: No data.
Bioaccumulation: log Kow = 1.8 (method unknown).
Toxicity: No data.
PEC is based on sales data in Sweden in year 2019. PEC = 0.0014 μg/L. "Calculation of a risk ratio is not possible, due to the lack of environmental toxicity data. Therefore, the following phrase is used: Risk of environmental impact of Timolol cannot be excluded, since no ecotoxicity data are available. However, according to the European Medicines Agency guideline on environmental risk assessment of medicinal products (EMA/CHMP/SWP/44447/00 corr2), the use of Timolol is unlikely to represent a risk for the environment, given that its predicted environmental concentration (PEC) is below the action limit 0.01 μg/L."
Author: Health and Medical Care Administration, Region Stockholm