Ecotoxicity and screening level ecotoxicological risk assessment of five antimicrobial agents: triclosan, triclocarban, resorcinol, phenoxyethanol and p-thymol

J Appl Toxicol. 2013 Nov;33(11):1222-9. doi: 10.1002/jat.2771. Epub 2012 Jul 13.


Acute and chronic (or sub-chronic) toxicity of five selected antimicrobial agents, including triclosan (TCS), triclocarban (TCC), resorcinol, phenoxyethanol and p-thymol, was investigated using the conventional three-aquatic-organism battery. These compounds are widely used in cosmetics and other personal care products and their ecological risk has recently become a significant concern. As results of toxicity tests, TCS was found to be most strongly toxic for green algae [e.g. 72 h no observed effect concentration (NOEC) of 0.50 µg l(-1) ] among the selected compounds, followed by TCC, while TCC was more toxic or similar to TCS for Daphnia and fish (e.g. Daphnia 8 day NOEC of 1.9 µg l(-1) ). Having compared the predicted no effect concentration (PNEC) determined from the toxicity data with measured environmental concentrations (MEC), the preliminary ecological risk assessment of these five antimicrobials was conducted. The MEC/PNEC ratios of TCS and TCC were over 1 for some monitoring data, especially in urban streams with watershed areas without sewage service coverage, and their potential risk for green algae and Daphnia might be at a level of concern, although the contribution of TCS/TCC on the total toxicity of the those sites needs to be further investigated. For the three other antimicrobials, the maximum MEC/PNEC ratio for resorcinol was 0.1-1, but those for phenoxyethanol and p-thymol were <0.1 and their risk to aquatic organisms is limited, although the additive effects with TCS, TCC and other antimicrobial agents, such as parabens, need to be further examined in future studies.

Keywords: Ceriodaphnia dubia; antimicrobial agents; ecological risk; ecotoxicity; green algae; phenoxyethanol; triclocarban; triclosan.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Infective Agents / chemistry
  • Anti-Infective Agents / toxicity*
  • Carbanilides / chemistry
  • Carbanilides / toxicity
  • Chlorophyta / drug effects*
  • Chlorophyta / growth & development
  • Daphnia / drug effects
  • Daphnia / growth & development
  • Ecotoxicology*
  • Ethylene Glycols / chemistry
  • Ethylene Glycols / toxicity
  • Molecular Structure
  • Reproduction / drug effects
  • Resorcinols / chemistry
  • Resorcinols / toxicity
  • Risk Assessment
  • Thymol / chemistry
  • Thymol / toxicity
  • Toxicity Tests, Acute
  • Toxicity Tests, Chronic
  • Triclosan / chemistry
  • Triclosan / toxicity
  • Water Pollutants, Chemical / toxicity*


  • Anti-Infective Agents
  • Carbanilides
  • Ethylene Glycols
  • Resorcinols
  • Water Pollutants, Chemical
  • Thymol
  • Triclosan
  • triclocarban
  • phenoxyethanol
  • resorcinol