Occurrence and toxicity of antimicrobial triclosan and by-products in the environment

Introduction and aims  

A review was undertaken on the occurrence, toxicity, and degradation of triclosan (TCS; 5-chloro-2,4-dichlorophenoxy)phenol) in the environment. TCS is a synthetic, broad-spectrum antibacterial agent incorporated in a wide variety of household and personal care products such as hand soap, toothpaste, and deodorants but also in textile fibers used in a range of other consumer products (e.g., toys, undergarments and cutting boards among other things).     

Ecological assessment of French Atlantic lakes based on phytoplankton, phytobenthos and macrophytes

Biological elements, including phytoplankton, phytobenthos, macrophytes, benthic invertebrates and fish, are employed by the EU Water Framework Directive (WFD) 2000/60/EC as ecological indicators for the assessment of surface waters. The use of primary producers (phytoplankton, phytobenthos and macrophytes) for water quality assessment has a long history, and several methods have been developed worldwide. In this study, we used these three communities to assess the ecological status of five natural lakes located in the Aquitaine region (southwest France). Several biological indices used in lakes from other European countries or in French rivers were employed and compared among the three communities. Each primary producer provided complementary information about the ecological status of the lakes, including the invasiveness of exotic taxa. Regardless of the producer community used, the response to the environment, as reflected by the indices (adequate for each community), was similar: Lakes Cazaux, Lacanau and Hourtin showed the best ecological status and Parentis and Soustons the worst. Phytoplankton diagnosis reflected and integrated unambiguously the water quality of the lakes, as demonstrated by the strong relationships between the phytoplankton index and the trophic status criteria. This community appeared as the best indicator, especially when macrophytes were absent. The methods applied here represent a potential tool for the assessment of the ecological status in the context of WFD, but they need to be refined. We propose modifications for phytobenthos index initially tailored for running waters for adequate use in lentic ecosystems. Indices for the three primary producers should be modified to incorporate exotic species which may provide information on potential biodiversity losses.     

Assessing the transformation kinetics of 2- and 4-nitrophenol in the atmospheric aqueous phase. Implications for the distribution of both nitroisomers in the atmosphere

Different transformation processes for nitrophenols in the atmospheric aqueous phase were considered to assess their relative importance, and their ability to account for the higher occurrence of 4-nitrophenol (4NP) compared to 2-nitrophenol (2NP) in the atmosphere. The importance of the different processes was in the order ^?OH > ^?NO₃ > direct photolysis > nitration to 2,4-dinitrophenol. 2NP is more reactive than 4NP with the hydroxyl radical, but the difference is low. Accordingly, such a process could account for the higher atmospheric occurrence of 4NP only if the observed atmospheric nitrophenols were what was left of an almost complete degradation by ^?OH. This would imply the unlikely scenario that the known nitrophenol sources to the atmosphere were only a limited fraction of the actual ones. A more likely, tentative possibility would be connected with the higher occurrence of 4NP on particles. If the reactivity order of nitrophenols in the atmospheric compartments was water droplets > gas phase > particles, particulate matter could act as a reservoir of 4NP. 2NP would undergo degradation in gas phase or solution at a higher rate than 4NP on particles, which could decrease the atmospheric levels of 2NP below those of 4NP.     

Combining polar organic chemical integrative samplers (POCIS) with toxicity testing to evaluate pesticide mixture effects on natural phototrophic biofilms

Polar organic chemical integrative samplers (POCIS) are valuable tools in passive sampling methods for monitoring polar organic pesticides in freshwaters. Pesticides extracted from the environment using such methods can be used to toxicity tests. This study evaluated the acute effects of POCIS extracts on natural phototrophic biofilm communities. Our results demonstrate an effect of POCIS pesticide mixtures on chlorophyll a fluorescence, photosynthetic efficiency and community structure. Nevertheless, the range of biofilm responses differs according to origin of the biofilms tested, revealing spatial variations in the sensitivity of natural communities in the studied stream. Combining passive sampler extracts with community-level toxicity tests offers promising perspectives for ecological risk assessment.     

Short term recovery of periphyton photosynthesis after pulse exposition to the photosystem II inhibitors atrazine and isoproturon

Aquatic organisms are exposed to fluctuating concentrations of herbicides which contaminate rivers following their use for agricultural or domestic purposes. The development of sensitive bioanalytical tests enabling us not only to detect the effects of those pollutants but to take into account this pattern of exposure should improve the ecological relevance of river toxicity assessment. In this respect, the use of chlorophyll fluorescence measurements is a convenient way to probe the effect of photosystem II (PSII) inhibitors on primary producers. This study was devoted to validate the combined use of two fluorescence parameters, the effective and the optimal quantum yields of PSII photochemistry (Φ_PSII and F_v/F_m), as reliable biomarkers of initial isoproturon (IPU) or atrazine (ATZ) toxicity to natural periphyton in a pulse exposition scenario. Φ_PSII and F_v/F_m were regularly estimated during a 7 h-exposure to each pollutant (0-100 μM) and also later after being transferred in herbicide-free water (up to 36 h). Our results showed that IPU was more toxic than ATZ, but with effects reversible within 12 h. Moreover, these two similarly acting herbicides (i.e. same target site) presented contrasted short term recovery patterns, regarding the previous exposure duration.     

Toxicity assessment of collected fractions from an extracted naphthenic acid mixture

Recent expansion within the oil sands industry of the Athabasca Basin of Alberta, Canada has led to increased concern regarding process-affected wastewaters produced during bitumen extraction. Naphthenic acids (NAs) have been identified as the primary toxic constituents of oil sands process-affected waters (OSPW) and studies have shown that with time, microbial degradation of lower molecular weight NAs has led to a decrease in observed toxicity. As earlier studies identified the need for an "unequivocal demonstration" of lower molecular weight NAs being the primary contributors to mixture toxicity, a study was initiated to fractionate an extracted NA mixture by molecular weight and to assess each fraction's toxicity. Successful molecular weight fractionation of a methylated NA mixture was achieved using a Kugelrohr distillation apparatus, in which fractions collected at higher boiling points contained NAs with greater total carbon content as well as greater degree of cyclicity. Assays with Vibrio fischeri bioluminescence (via Microtox assay) revealed that the lowest molecular weight NAs collected had higher potency (EC50: 41.9+/-2.8 mg l(-1)) than the highest molecular weight NAs collected (EC50: 64.9+/-7.4 mg l(-1)). Although these results support field observations of microbial degradation of low molecular weight NAs decreasing OSPW toxicity, it is not clear why larger NAs, given their greater hydrophobicity, would be less toxic.     

Towards a renewed research agenda in ecotoxicology

New concerns about biodiversity, ecosystem services and human health triggered several new regulations increasing the need for sound ecotoxicological risk assessment. The PEER network aims to share its view on the research issues that this challenges. PEER scientists call for an improved biologically relevant exposure assessment. They promote comprehensive effect assessment at several biological levels. Biological traits should be used for Environmental risk assessment (ERA) as promising tools to better understand relationships between structure and functioning of ecosystems. The use of modern high throughput methods could also enhance the amount of data for a better risk assessment. Improved models coping with multiple stressors or biological levels are necessary to answer for a more scientifically based risk assessment. Those methods must be embedded within life cycle analysis or economical models for efficient regulations. Joint research programmes involving humanities with ecological sciences should be developed for a sound risk management.     

Radioactivity levels in major French rivers: summary of monitoring chronicles acquired over the past thirty years and current status

Since the beginning of the 1990 s, liquid releases of gamma-emitting radionuclides from French nuclear facilities have generally fallen by almost 85%. Almost 65% of gamma-emitting liquid effluents released into freshwater rivers concerned the River Rh?ne (Southeast France), with around 85% of this originating from the Marcoule spent fuel reprocessing plant. Upstream of French nuclear plants, artificial radionuclides still detected by gamma spectrometry in 2006, include (137)Cs, (131)I as well as (60)Co, (58)Co and (54)Mn in the case of the Rhine (Switzerland nuclear industries). In the wake of the fallout from the Chernobyl accident, (103)Ru, (106)Rh-Ru, (110 m)Ag, (141)Ce and (129)Te were detected in rivers in the east of France. Some of these radionuclides were found in aquatic plants until 1989. In eastern France, (137)Cs activity in river sediments and mosses is still today two to three times greater than that observed in similar environments in western France. No (134)Cs has been detected upstream of nuclear plants in French rivers since 2001. Downstream of nuclear plants, the gamma emitters still detected regularly in rivers in 2006 are (137)Cs, (134)Cs, (60)Co, (58)Co, (110 m)Ag, (54)Mn, (131)I, together with (241)Am downstream of the Marcoule spent fuel reprocessing plant. Alpha and beta emitters such as plutonium isotopes and (90)Sr first entered freshwaters at the early 1950s due to the leaching of soils contaminated by atmospheric fallout from nuclear testing. These elements were also introduced, in the case of the Rh?ne River, via effluent from the Marcoule reprocessing plant. Until the mid 1990 s, plutonium isotope levels observed in the lower reaches of the Rh?ne were 10 to 1000 times higher than those observed in other French freshwaters. Data gathered over a period of almost thirty years of radioecological studies reveal that the only radionuclides detected in fish muscles are (137)Cs, (90)Sr, plutonium isotopes and (241)Am. At the scale of the French territory, there is no significant difference since the mid 1990 s between (137)Cs activity observed downstream of nuclear facilities and that observed upstream, whether in sediments, mosses and fish. Finally, this study highlights that the natural radioactivity of surface freshwaters are around 25 times greater than artificial radioactivity from gamma emitters. However, non gamma emitters released by nuclear industries, such as (3)H, may lead to artificial activity levels 2 to 20 times higher than natural levels.