The T-value in the score for hazard refers to acute toxicity. Underlying data for P, B and T are from Fass.se, see below.
Concentrations of tetracycline in wastewater treatment plants is likely to select for bacterial resistance. Studies have shown that even low concentrations of antibiotics in the environment may contribute to antibiotic resistance and should therefore be taken to ensure that as little as possible end up in our environment.
Tetracycline is included in the Stockholm County Council's table of pharmaceuticals with risk for negative environmental impact according to the environmental program 2017–2021. Tetracycline has been detected in treated wastewater in Stockholm County in the last five years (2012–2016).
Fass environmental information for Tetracyklin Meda (tetracycline) (downloaded 2018-07-10).
Persistence: "The inherent degradability of Tetracycline was determined in a combined test design based on the Zahn-Wellens test (OECD 302B, 1992) and the CO2-evolution test (OECD 301B, 1992). Tetracycline did not pass the criteria for inherent biodegradability as the test resulted in <70% degradation in 7 days."
Bioaccumulation: "Log P of -1,30 (unknown method)."
Acute toxicity: There are data for 2 trophic levels, lowest for cyanobacteria (Microcystis aeruginosa) 0.09 mg/L.
Sales data in Sweden are available for 2014. PEC/PNEC: "Since there are not sufficient data for the calculation of PNEC, the phrase “Risk of environmental impact of Tetracycline cannot be excluded, since there is not sufficient ecotoxicity data available” is used."
Concrete proposals on how to work to reduce emissions of environmentally harmful pharmaceuticals on the list have been developed in close cooperation with the Stockholm Drug and Therapeutics Committee's expert advice. The action proposals were developed from an environmental perspective. The patient's best always goes first and several pharmaceuticals on the list are also included in the Wise list. However, for such pharmaceuticals, there may be measures that could reduce the environmental impact.
Concrete proposal for tetracycline
Comparative assessment of environmental risk and risk of resistance selection in human use of ivermectin, metronidazole, lymecycline and azelaic acid in Sweden.
The risk is clearly highest for lymecycline based on measured concentrations of tetracycline in uncleaned waste water that exceeds experimental established selective levels for antibiotic resistance in bacteria. A similar but lower risk profile exists for metronidazole based on total use but with significantly lower empirical support for the efficacy The topical use of metronidazole results in a negligible risk of resistance selection in waste water treatment plants. The risk of effects of human use of ivermectin is also low, given an expected contribution to exposure in aquatic environments at subnanogram levels, and a majority of efficacy studies that show significantly higher levels of efficacy. Since there is (at least) a study that reports effects at 1 pg/L, however, one can not completely rule out risk. For azelaic acid there is nothing that indicates an environmental hazard.
Author: The Pharmaceutical unit of Region Stockholm