An ecological risk assessment for triclosan in lotic systems following discharge from wastewater treatment plants in the United States

Abstract

A modeling study was conducted to examine the distribution of concentrations of the antimicrobial triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether) in rivers following discharge from wastewater treatment plants (WWTPs). Most uses of triclosan are disposed of down residential drains and ultimately reach WWTPs. A modeling analysis was conducted to simulate the discharge of triclosan in WWTP effluents to rivers and calculate the expected concentrations based on characteristics of the reach where the discharge occurred, the estimated concentration of triclosan in the WWTP effluent, and the physicochemical properties of triclosan. A probabilistic exposure assessment was conducted based on data on the characteristics of U.S. reaches receiving wastewater discharges and the physicochemical characteristics of triclosan. A risk assessment was conducted by comparing the estimated concentrations with toxicity endpoint concentrations for species representative of key ecological groups. For fish and invertebrates, neither acute nor chronic risks are of concern, and no concerns exist for vascular aquatic plants. However, certain types of algae are the most sensitive species to triclosan by more than an order of magnitude than other algal or aquatic plant species. For these algae, the potential exists for some risk from triclosan exposure near the WWTP discharge location during low-flow-rate periods for some WWTPs with small dilutions. The risks downstream are lower because of dissipation of triclosan.

Microbial Resistance to Tridosan: A Case Study in Natural Selection

“…48 Since wastewater treatment plants fail to remove triclosan from the water and the compound is highly stable for long periods of time, 49 a huge amount of triclosan is expected to be emi� ed into waterways. In a U.S. Geological Survey study of 95 diff erent organic wastewater contaminants in U.S. streams, triclosan was one of the most frequently detected compounds, and in How Does FDA Regulate Antimicrobials?…”

“…55 The risks are especially high immediately downstream from wastewater treatment plants. 56 Because of its lipophilic nature and resistance to degradation, triclosan in waterways is readily available for absorption and bioaccumulation by aquatic organisms in the environment. 57 Researchers in Sweden found high levels of triclosan present in the bile of fi sh that were placed in cages downstream of sewage treatment works in Sweden.…”

Degradation of Triclosan by Photo-Fenton like Oxidation

“…Additionaly, it is a white powdered solid with a slight aromatic/phenolic odor and with low soluble in water (12 mg/L) [2]. Table 1 [2,3,4].…”

“…Additionaly, it is a white powdered solid with a slight aromatic/phenolic odor and with low soluble in water (12 mg/L) [2]. Table 1 [2,3,4]. As can be seen in Table 1, triclosan has a highly hydrophobic nature with high log KOW value as 4.76 that it is likely to be absorbed in sediment with high organic carbon content.…”

Simplified Derivatization Method for Triclosan Determination in Personal Care Products by Gas Chromatography‐Mass Spectrometry

“…Hence they can disturb the ecosystem due to their toxicity to aquatic organisms. 5,6 However, information on the content of TCS in many PCPs in Taiwan is unavailable. Therefore, the concentration of TCS in PCPs and the associated environmental risk are not assessable, and concentrations of TCS in municipal effluents and wastewaters could not be evaluated.…”