Occurrence and environmental behavior of the bactericide triclosan and its methyl derivative in surface waters and in wastewater

Fate of Triclosan and Methyltriclosan in soil from biosolids application

This study investigates the persistence of Triclosan (TCS), and its degradation product, Methyltriclosan (MeTCS), after land application of biosolids to an experimental agricultural plot under both till and no till. Surface soil samples (n = 40) were collected several times over a three years period and sieved to remove biosolids. Concentration of TCS in the soil gradually increased with maximum levels of 63.7 ± 14.1 ng g(-1) dry wt., far below the predicted maximum concentration of 307.5 ng g(-1) dry wt. TCS disappearance corresponded with MeTCS appearance, suggesting in situ formation. Our results suggest that soil incorporation and degradation processes are taking place simultaneously and that TCS background levels are achieved within two years. TCS half-life (t(0.5)) was determined as 104 d and MeTCS t(0.5), which was more persistent than TCS, was estimated at 443 d.

Biodegradation of triclosan in biosolids-amended soils

Land application of biosolids can constitute an important source of triclosan (TCS) input to soils, with uncertain effects. Several studies have investigated the degradation potential of TCS in biosolids-amended soils, but the results vary widely. We conducted a laboratory degradation study by mixing biosolids spiked with [¹⁴C]-TCS (final concentration = 40 mg/kg) with Immokalee fine sand and Ashkum silty clay loam soils at an agronomic application rate (22 Mg/ha). Biosolids-amended soils were aerobically incubated in biotic and inhibited conditions for 18 weeks. Subsamples removed at 0, 2, 4, 6, 9, 12, 15, and 18 weeks were sequentially extracted with an operationally defined extraction scheme to determine labile and nonlabile TCS fractions. Over the 18-week incubation, the proportion of [¹⁴C] in the nonlabile fraction increased and the labile fraction decreased, suggesting decreasing availability to biota. Partitioning of TCS into labile and nonlabile fractions depended on soil characteristics. Less than 0.5% of [¹⁴C]-TCS was mineralized to carbon dioxide (¹⁴CO₂) in both soils and all treatments. A degradation metabolite, methyl triclosan (Me-TCS), was identified in both soils only in the biotic treatment, and increased in concentration over time. Even under biotic conditions, biosolids-borne TCS is persistent, with a primary degradation (TCS to Me-TCS) half-life of 78 d in the silty clay loam and 421 d in the fine sand. A half-life of approximately 100 d would be a conservative first approximation of TCS half-life in biosolids-amended soils for risk estimation.

Triclosan: environmental exposure, toxicity and mechanisms of action

Triclosan [5-chloro-2-(2,4-dichlorophenoxy)phenol; TCS] is a broad spectrum antibacterial agent used in personal care, veterinary, industrial and household products. TCS is commonly detected in aquatic ecosystems, as it is only partially removed during the wastewater treatment process. Sorption, biodegradation and photolytic degradation mitigate the availability of TCS to aquatic biota; however the by-products such as methyltriclosan and other chlorinated phenols may be more resistant to degradation and have higher toxicity than the parent compound. The continuous exposure of aquatic organisms to TCS, coupled with its bioaccumulation potential, have led to detectable levels of the antimicrobial in a number of aquatic species. TCS has been also detected in breast milk, urine and plasma, with levels of TCS in the blood correlating with consumer use patterns of the antimicrobial. Mammalian systemic toxicity studies indicate that TCS is neither acutely toxic, mutagenic, carcinogenic, nor a developmental toxicant. Recently, however, concern has been raised over TCS's potential for endocrine disruption, as the antimicrobial has been shown to disrupt thyroid hormone homeostasis and possibly the reproductive axis. Moreover, there is strong evidence that aquatic species such as algae, invertebrates and certain types of fish are much more sensitive to TCS than mammals. TCS is highly toxic to algae and exerts reproductive and developmental effects in some fish. The potential for endocrine disruption and antibiotic cross-resistance highlights the importance of the judicious use of TCS, whereby the use of TCS should be limited to applications where it has been shown to be effective.

Reprint of: Removal and formation of chlorinated triclosan derivatives in wastewater treatment plants using chlorine and UV disinfection

Triclosan, a common antimicrobial agent, may react during the disinfection of wastewater with free chlorine to form three chlorinated triclosan derivatives (CTDs). This is of concern because the CTDs may be photochemically transformed to tri- and tetra-chlorinated dibenzo-p-dioxins when discharged into natural waters. In this study, wastewater influent, secondary (pre-disinfection) effluent, and final (post-disinfection) effluent samples were collected on two occasions each from two activated sludge wastewater treatment plants, one using chlorine disinfection and one using UV disinfection. Concentrations of triclosan and three CTDs were determined using ultra performance liquid chromatography-triple quadrupole mass spectrometry with isotope dilution methodology. Triclosan and the CTDs were detected in every influent sample at levels ranging from 453 to 4530 and 2 to 98 ng L(-1), respectively, though both were efficiently removed from the liquid phase during activated sludge treatment. Triclosan concentrations in the pre-disinfection effluent ranged from 36 to 212 ng L(-1), while CTD concentrations were below the limit of quantification (1 ng L(-1)) for most samples. In the treatment plant that used chlorine disinfection, triclosan concentrations decreased while CTDs were formed during chlorination, as evidenced by CTD levels as high as 22 ng L(-1) in the final effluent. No CTDs were detected in the final effluent of the treatment plant that used UV disinfection. The total CTD concentration in the final effluent of the chlorinating treatment plant reached nearly one third of the triclosan concentration, demonstrating that the chlorine disinfection step played a substantial role in the fate of triclosan in this system.

Removal and formation of chlorinated triclosan derivatives in wastewater treatment plants using chlorine and UV disinfection

Triclosan, a common antimicrobial agent, may react during the disinfection of wastewater with free chlorine to form three chlorinated triclosan derivatives (CTDs). This is of concern because the CTDs may be photochemically transformed to tri- and tetra-chlorinated dibenzo-p-dioxins when discharged into natural waters. In this study, wastewater influent, secondary (pre-disinfection) effluent, and final (post-disinfection) effluent samples were collected on two occasions each from two activated sludge wastewater treatment plants, one using chlorine disinfection and one using UV disinfection. Concentrations of triclosan and three CTDs were determined using ultra performance liquid chromatography-triple quadrupole mass spectrometry with isotope dilution methodology. Triclosan and the CTDs were detected in every influent sample at levels ranging from 453 to 4530 and 2 to 98 ng L(-1), respectively, though both were efficiently removed from the liquid phase during activated sludge treatment. Triclosan concentrations in the pre-disinfection effluent ranged from 36 to 212 ng L(-1), while CTD concentrations were below the limit of quantification (1 ng L(-1)) for most samples. In the treatment plant that used chlorine disinfection, triclosan concentrations decreased while CTDs were formed during chlorination, as evidenced by CTD levels as high as 22 ng L(-1) in the final effluent. No CTDs were detected in the final effluent of the treatment plant that used UV disinfection. The total CTD concentration in the final effluent of the chlorinating treatment plant reached nearly one third of the triclosan concentration, demonstrating that the chlorine disinfection step played a substantial role in the fate of triclosan in this system.

Biodegradation of triclosan and formation of methyl-triclosan in activated sludge under aerobic conditions

Triclosan is an antimicrobial agent which is widely used in household and personal care products. Widespread use of this compound has led to the elevated concentrations of triclosan in wastewater, wastewater treatment plants (WWTPs) and receiving waters. Removal of triclosan and formation of triclosan-methyl was investigated in activated sludge from a standard activated sludge WWTP equipped with enhanced biological phosphorus removal. The removal was found to occur mainly under aerobic conditions while under anoxic (nitrate reducing) and anaerobic conditions rather low removal rates were determined. In a laboratory-scale activated sludge reactor 75% of the triclosan was removed under aerobic conditions within 150 h, while no removal was observed under anaerobic or anoxic conditions. One percent of the triclosan was converted to triclosan-methyl under aerobic conditions, less under anoxic (nitrate reducing) and none under anaerobic conditions.

Aquivalence revisited--new model formulation and application to assess environmental fate of ionic pharmaceuticals in Hamilton Harbour, Lake Ontario

A model formulation based on "aquivalence", as defined in terms of activity is presented to estimate the multimedia fate of ionizing chemicals. The aquivalence approach is analogous to fugacity but aquivalence is applicable to neutral and ionizing compounds, and has been applied previously to speciating chemicals, notably metals. The new aquivalence-based mass-balance model treats ionizing organic compounds that exist as interconverting neutral and ionic species which are subject to fate processes at differing rates. The model is illustrated by application to four ionizing pharmaceuticals in Hamilton Harbour, Lake Ontario. At the system pH of 7.9-8.5, ibuprofen, gemfibrozil, and naproxen are expected to be almost entirely ionic and triclosan split between ionic and neutral forms. Measured seasonal surface water concentrations, which were 2-10 times lower in the late summer and fall than during spring, were used to solve for unknown values of chemical half-life in the water column due to degradation (photo- and bio-) of the ionizing and neutral forms and secondarily, ionic sorption coefficients of the ionizing forms. Model estimates of half-lives in the habour's water ranged from 11 to 77, 11 to 147 and 10 to 37 for ionic ibuprofen, gemfibrozil, and naproxen, respectively; and 4-22 days and 2-9 days for ionic and neutral triclosan, respectively, with the shortest half-lives in spring and the longest in summer.

Effects of triclocarban, triclosan, and methyl triclosan on thyroid hormone action and stress in frog and mammalian culture systems

Triclosan (TCS) and triclocarban (TCC) are widely used broad spectrum bactericides that are common pollutants of waterways and soils. Methyl triclosan (mTCS) is the predominant bacterial TCS metabolite. Previous studies have shown that TCS disrupts thyroid hormone (TH) action; however, the effects of mTCS or TCC are not known. The present study uses the cultured frog tadpole tail fin biopsy (C-fin) assay and the TH-responsive rat pituitary GH3 cell line to assess the effects of these three chemicals (1-1000 nM) on TH signaling and cellular stress within 48 h. mRNA abundance of TH receptor β, Rana larval keratin type I (TH-response), heat shock protein 30, and catalase (stress-response) was measured using quantitative real-time polymerase chain reaction in the C-fin assay. The TH-responsive gene transcripts encoding growth hormone, deiodinase I, and prolactin were measured in GH3 cells with the heat shock protein 70 transcript acting as a cellular stress indicator. We found alteration of stress indicators at a wide range of concentrations of TCS, mTCS, and TCC in both test systems. mTCS and TCC affected TH-responsive gene transcripts at the highest concentration in mammalian cells, whereas a modest effect included lower concentrations in the C-fin assay. In contrast, TCS did not affect TH-responsive transcripts. These results identify nontarget biological effects of these bacteriocides on amphibian and mammalian cells and suggest the TH-disrupting effects observed for TCS could be mediated through its metabolite.

Triclosan affects the microbial community in simulated sewage-drain-field soil and slows down xenobiotic degradation

Effects of the common antibacterial agent triclosan on microbial communities and degradation of domestic xenobiotics were studied in simulated sewage-drain-field soil. Cultivable microbial populations decreased 22-fold in the presence of 4 mg kg⁻¹ of triclosan, and triclosan-resistant Pseudomonas strains were strongly enriched. Exposure to triclosan also changed the general metabolic profile (Ecoplate substrate profiling) and the general profile (T-RFLP) of the microbial community. Triclosan degradation was slow at all concentrations tested (0.33-81 mg kg⁻¹) during 50-days of incubation. Mineralization experiments (¹⁴C-tracers) and chemical analyses (LC-MS/MS) showed that the persistence of a linear alkylbenzene sulfonate (LAS) and a common analgesic (ibuprofen) increased with increasing triclosan concentrations (0.16-100 mg kg⁻¹). The largest effect was seen for LAS mineralization which was severely reduced by 0.16 mg kg⁻¹ of triclosan. Our findings indicate that environmentally realistic concentrations of triclosan may affect the efficiency of biodegradation in percolation systems.

Photodegradation of the synthetic fragrance OTNE and the bactericide triclosan adsorbed on dried loamy sand--results from models and experiments

Fragrances such as OTNE (marketed as Iso-E-Super®) and bactericides such as triclosan (marketed as Igrasan) are present in waste water and thus finally sorbed to sewage sludge. With that sludge they can reach agricultural fields where they potentially can undergo photodegradation processes. In this study the photodegradation of OTNE and triclosan on dried loamy sand was measured under artificial sunlight conditions in laboratory experiments. These compounds were artificially added with concentrations of 1 μg g(-1) on pre-rinsed dried loamy sand. The decrease in concentration with light irradiation was measured for 32d in comparison to soil samples without light irradiation. The estimated light source intensity was 27 W m(-2). Within the experiment, the apparent half-life was 7 and 17d for OTNE and triclosan respectively. The decrease did not simply follow first-order kinetics. The apparent rate constant decreased in the latter stage of reaction, suggesting that part of the chemicals were inaccessible for degradation. Two models, i.e., a diffusion-limited model, and a light penetration-limited model, were used in comparison to the measured data to explain the observed degradation limitations in the latter stages of the experiments. Comparing the hereby obtained model parameters with estimated physico-chemical parameters for the soil and the two chemical compounds, the light penetration-limited model, in which the degradation in the soil surface layer is assumed to be limited due to the shading effect of light in the upper thin soil layer, showed to be the most realistic in describing the photodegradation.

A review of personal care products in the aquatic environment: environmental concentrations and toxicity

Considerable research has been conducted examining occurrence and effects of human use pharmaceuticals in the aquatic environment; however, relatively little research has been conducted examining personal care products although they are found more often and in higher concentrations than pharmaceuticals. Personal care products are continually released into the aquatic environment and are biologically active and persistent. This article examines the acute and chronic toxicity data available for personal care products and highlights areas of concern. Toxicity and environmental data were synergized to develop a preliminary hazard assessment in which only triclosan and triclocarban presented any hazard. However, numerous PCPs including triclosan, paraben preservatives, and UV filters have evidence suggesting endocrine effects in aquatic organisms and thus need to be investigated and incorporated in definitive risk assessments. Additional data pertaining to environmental concentrations of UV filters and parabens, in vivo toxicity data for parabens, and potential for bioaccumulation of PCPs needs to obtained to develop definitive aquatic risk assessments.

GC-MS analysis and ecotoxicological risk assessment of triclosan, carbamazepine and parabens in Indian rivers

Pharmaceutical and personal care products are used extensively worldwide and their residues are frequently reported in aquatic environments. In this study, antiepileptic, antimicrobial and preservative compounds were analyzed in surface water and sediment from the Kaveri, Vellar and Tamiraparani rivers, and in the Pichavaram mangrove in India by gas chromatography-mass spectrometry (GC-MS). The mean concentration of carbamazepine recorded in the Kaveri River water (28.3 ng/L) was higher than in the other rivers and the mangrove. Because carbamazepine is used only in human drugs, this may reflect the relative contributions of human excretions/sewage in these rivers. The mean triclosan level in the Tamiraparani River (944 ng/L) was an order of magnitude greater than in the other water systems, and the concentrations at two of the sites reported here (3800-5160 ng/L) are, to our best knowledge, among the highest detected in surface waters. Sediment levels were, however, comparable with other sites. We conclude that industrial releases are likely major contributors of triclosan into this river system. Among parabens, ethyl paraben was predominantly observed. Hazard Quotients suggest greater environmental risks for triclosan than for carbamazepine and parabens. This is the first study on antiepileptic, antimicrobial and preservatives in rivers and mangroves from India.

Oxidation of triclosan by ferrate: reaction kinetics, products identification and toxicity evaluation

The oxidation of triclosan by commercial grade aqueous ferrate (Fe(VI)) was investigated and the reaction kinetics as a function of pH (7.0-10.0) were experimentally determined. Intermediate products of the oxidation process were characterized using both GC-MS and RRLC-MS/MS techniques. Changes in toxicity during the oxidation process of triclosan using Fe(VI) were investigated using Pseudokirchneriella subcapitata growth inhibition tests. The results show that triclosan reacted rapidly with Fe(VI), with the apparent second-order rate constant, k(app), being 754.7 M(-1) s(-1) at pH 7. At a stoichiometric ratio of 10:1 (Fe(VI):triclosan), complete removal of triclosan was achieved. Species-specific rate constants, k, were determined for reaction of Fe(VI) with both the protonated and deprotonated triclosan species. The value of k determined for neutral triclosan was 6.7(±1.9)×10(2) M(-1) s(-1), while that measured for anionic triclosan was 7.6(±0.6)×10(3) M(-1) s(-1). The proposed mechanism for the oxidation of triclosan by the Fe(VI) involves the scission of ether bond and phenoxy radical addition reaction. Coupling reaction may also occur during Fe(VI) degradation of triclosan. Overall, the degradation processes of triclosan resulted in a significant decrease in algal toxicity. The toxicity tests showed that Fe(VI) itself dosed in the reaction did not inhibit green algae growth.

Effects of triclosan on soil microbial respiration

The antimicrobial substance triclosan has widespread use in personal care products and can enter the terrestrial environment if sewage sludge is applied to soil. The inhibitory effects of triclosan on basal and substrate-induced respiration (SIR) of three different soils were investigated. Soils were dosed and later redosed with four nominal triclosan concentrations, and respiration rates were measured over time. In each soil, a significant depression in basal respiration was noted after initial dosing, followed by a recovery. The initial extent of respiration inhibition was positively related to the triclosan dose, i.e., respiration was most inhibited at highest triclosan concentration. Differences in respiration inhibition between soils at equivalent dose were inversely correlated with organic matter and clay content, suggesting that the bioavailability of triclosan might have been reduced by sorption to organic carbon or by physical protection in micropores. Substrate-induced respiration was also reduced by the addition of triclosan and subsequently recovered. After redosing with triclosan, basal respiration was enhanced in all soils, suggesting that it was acting as a substrate. However, redosing resulted in SIR inhibition in all treatments above 10 mg triclosan kg(-1) in all three soils, although all soils appeared to be more resistant to perturbation than following initial dosing. The present study suggests that triclosan inhibits soil respiration but that a subsequent acclimation of the microbial community occurs.

Influence of methylation on the antibacterial properties of triclosan in Pasteurella multocida and Pseudomonas aeruginosa variant strains

The opportunistic bacterium Pasteurella multocida is extremely susceptible to the hydrophobic biocide triclosan by virtue of its markedly permeable outer membrane, while the nosocomial pathogen Pseudomonas aeruginosa is intrinsically resistant to levels far exceeding the triclosan aqueous solubility limit. Widespread incorporation of triclosan in health and personal care products has resulted in its concomitant accumulation with metabolites such as methyl triclosan in environmental and biological systems. The present study was undertaken to investigate the possibility that methylation of triclosan may mitigate its antiseptic efficacy in healthcare settings, as well as represent a potential resistance mechanism. Comparative standardised disc agar diffusion and batch cultural turbidimetric bioassays were employed to assess the relationship between triclosan-susceptible or -resistant bacteria and methyl triclosan. A wild-type P. aeruginosa parental strain and a mutant exhibiting a permeable outer cell envelope phenotype were examined in concert with a refractory wild-type strain sensitised to triclosan susceptibility using outer membrane permeabiliser compound 48/80. All organisms examined were resistant to methyl triclosan, and all organisms excluding P. aeruginosa were susceptible to triclosan over a wide concentration range. The permeable outer membrane phenotype in both mutant and chemically sensitised wild-type strains rendered P. aeruginosa susceptible to triclosan, but not to methyl triclosan. These data support the notion that methylation of triclosan renders the compound unable to inhibit the growth of disparate bacterial pathogens in a manner independent of an intact outer membrane. It can also be concluded that biocide modification may contribute to the intrinsic resistance of P. aeruginosa to triclosan.

Occurrence and loss over three years of 72 pharmaceuticals and personal care products from biosolids-soil mixtures in outdoor mesocosms

Municipal biosolids are in widespread use as additives to agricultural soils in the United States. Although it is well known that digested sewage sludge is laden with organic wastewater contaminants, the fate and behavior of micropollutants in biosolids-amended agricultural soils remain unclear. An outdoor mesocosm study was conducted in Baltimore, Maryland, to explore the fate of 72 pharmaceuticals and personal care products (PPCPs) over the course of three years in that were placed in plastic containers made from polyvinylchloride and kept exposed to ambient outdoor conditions. Of the 72 PPCPs tested for using EPA Method 1694, 15 were initially detected in the soil/biosolids mixtures at concentrations ranging from low parts-per-billion to parts-per-million levels. The antimicrobials triclocarban and triclosan showed the highest initial concentrations at 2715 and 1265 μg kg(-1), respectively. Compounds showing no discernable loss over three years of monitoring included diphenhydramine, fluoxetine, thiabendazole and triclocarban. The following half-life estimates were obtained for compounds showing first-order loss rates: azithromycin (408-990 d) carbamazepine (462-533 d), ciprofloxacin (1155-3466 d), doxycycline (533-578 d), 4-epitetracycline (630 d), gemfibrozil (224-231 d), norfloxacin (990-1386 d), tetracycline (578 d), and triclosan (182-193 d). Consistent with other outdoor degradation studies, chemical half-lives determined empirically exceeded those reported from laboratory studies or predicted from fate models. Study results suggest that PPCPs shown in the laboratory to be readily biotransformable can persist in soils for extended periods of time when applied in biosolids. This study provides the first experimental data on the persistence in biosolids-amended soils for ciprofloxacin, diphenhydramine, doxycycline, 4-epitetracycline, gemfibrozil, miconazole, norfloxacin, ofloxacin, and thiabendazole.

Determination of biocides and pesticides by on-line solid phase extraction coupled with mass spectrometry and their behaviour in wastewater and surface water

This study focused on the input of hydrophilic biocides into the aquatic environment and on the efficiency of their removal in conventional wastewater treatment by a mass flux analysis. A fully automated method consisting of on-line solid phase extraction coupled to LC-ESI-MS/MS was developed and validated for the simultaneous trace determination of different biocidal compounds (1,2-benzisothiazoline-3-one (BIT), 3-Iodo-2-propynylbutyl-carbamate (IPBC), irgarol 1051 and 2-N-octyl-4-isothiazolinone (octhilinone, OIT), carbendazim, diazinon, diuron, isoproturon, mecoprop, terbutryn and terbutylazine) and pharmaceuticals (diclofenac and sulfamethoxazole) in wastewater and surface water. In the tertiary effluent, the highest average concentrations were determined for mecoprop (1010 ng/L) which was at comparable levels as the pharmaceuticals diclofenac (690 ng/L) and sulfamethoxazole (140 ng/L) but 1-2 orders of magnitude higher than the other biocidal compounds. Average eliminations for all compounds were usually below 50%. During rain events, increased residual amounts of biocidal contaminants are discharged to receiving surface waters.

Exploring Lemna gibba thresholds to nutrient and chemical stressors: differential effects of triclosan on internal stoichiometry and nitrate uptake across a nitrogen:phosphorus gradient

Nutrient enrichment often co-occurs with chemical stressors in aquatic ecosystems, but the impacts of these multiple stressors across nutrient gradients is poorly understood and not typically addressed in ecotoxicity studies of lower trophic level models. Moreover, laboratory assays performed to determine threshold responses of aquatic macrophytes to contaminants typically use growth and morphometric endpoints to establish threshold effects and seldom report other important functional responses of lower trophic levels. Using the aquatic macrophyte Lemna gibba, we examined influences of varying nitrogen (N) and phosphorus (P) levels in combination with triclosan, a widely used antimicrobial agent in consumer care products, on internal carbon (C):N:P and NO(3) (-) uptake kinetics. Triclosan modulated L. gibba tissue N and P content, and these stoichiometric responses for P-limited plants to triclosan exposure were more sensitive than growth endpoints employed in standardized phytotoxicity assays. Nitrate uptake capacities were also differentially inhibited by triclosan exposure according to external nutrient levels. Uptake rates for plants cultured and exposed under saturating N-levels were inhibited by more than threefold compared with N-limited plants. The results suggest that stoichiometric and nutrient uptake responses to chemical stressors provide useful information regarding adverse ecological thresholds not defined in standardized phytotoxicity assays with aquatic macrophytes. Our findings further indicate that site-specific impacts of chemicals associated with the wide ambient ranges of N and P typical of surface waters may be anticipated in lower trophic levels. Future studies should examine adverse effects of other stressors to these ecologically relevant endpoints, which may be useful in environmental assessment and management.

Erratum: Probabilistic application of a fugacity model to predict triclosan fate during wastewater treatment

The fate and partitioning of the antimicrobial compound, triclosan, in wastewater treatment plants (WWTPs) is evaluated using a probabilistic fugacity model to predict the range of triclosan concentrations in effluent and secondary biosolids. The WWTP model predicts 84% to 92% triclosan removal, which is within the range of measured removal efficiencies (typically 70% to 98%). Triclosan is predominantly removed by sorption and subsequent settling of organic particulates during primary treatment and by aerobic biodegradation during secondary treatment. Median modeled removal efficiency due to sorption is 40% for all treatment phases and 31% in the primary treatment phase. Median modeled removal efficiency due to biodegradation is 48% for all treatment phases and 44% in the secondary treatment phase. Important factors contributing to variation in predicted triclosan concentrations in effluent and biosolids include influent concentrations, solids concentrations in settling tanks, and factors related to solids retention time. Measured triclosan concentrations in biosolids and non-United States (US) effluent are consistent with model predictions. However, median concentrations in US effluent are over-predicted with this model, suggesting that differences in some aspect of treatment practices not incorporated in the model (e.g., disinfection methods) may affect triclosan removal from effluent. Model applications include predicting changes in environmental loadings associated with new triclosan applications and supporting risk analyses for biosolids-amended land and effluent receiving waters.

Simultaneous quantitation of parabens, triclosan, and methyl triclosan in indoor house dust using solid phase extraction and gas chromatography-mass spectrometry

An integrated analytical method for the simultaneous determination of five parabens (methyl-, ethyl-, propyl-, butyl-, and benzyl-), triclosan, and methyl triclosan in indoor house dust was developed based on gas chromatographic-mass spectrometric technique (GC/MS). Analytes were extracted from dust samples by sonication. After sample cleanup by solid-phase extraction (SPE), the extracts were derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) and then analyzed by gas chromatography coupled with ion trap mass spectrometry operated in multiple reaction monitoring (MRM) mode. For quantitation, isotope-labelled internal standards were used for each corresponding target analyte. Only 0.05 g of dust sample was needed for the analysis. Method detection limits ranged from 6.5 to 10 ng/g, and absolute recoveries from 74% to 92%. The developed method demonstrated good repeatability and reproducibility, with relative standard deviations (RSDs) less than 16% for all the analytes. The analytes were determined in dust samples collected using two vacuum sampling methods from 63 Canadian homes: a sample of fresh or "active" dust (FD) collected using a Pullman-Holt vacuum sampler, and a composite sample taken from the household vacuum cleaner (HD). Methyl paraben, propyl paraben, and triclosan were detected in all HD and FD samples. HD samples yielded median values for methyl paraben, propyl paraben, and triclosan of 1080, 463, and 378 ng/g, respectively, which were comparable to the FD sample medians of 1120, 618 and 571 ng/g. Ethyl paraben was detected at frequencies of 89% in FD and 73% in HD samples, with median values of 52 and 25 ng/g, respectively. Butyl paraben was detected at frequencies of 44% in FD and 75% in HD samples, with median values of <10 and 59 ng/g, respectively. Benzyl paraben and methyl triclosan were not detected in any of the samples collected by either method. Samples collected according to the fresh dust protocol agreed with the household vacuum samples 90% of the time. Widely scattered concentration levels were observed for target analytes from this preliminary set of 63 Canadian samples, which suggests a wide variability in Canadian household exposures to these chemicals.

Triclocarban and triclosan biodegradation at field concentrations and the resulting leaching potentials in three agricultural soils

This study evaluated the leaching potential of the antimicrobials triclocarban (TCC) and triclosan (TCS) in three agricultural soils using a simple model based on biodegradation and adsorption. The antimicrobials were added to the soils at two moisture levels (10% or 15% w/w) to achieve initial concentrations of 0.05, 0.2, or 2 mg kg(-1). The low concentrations (0.05, 0.2 mg kg(-1)) are more representative of field concentrations, important because previous studies have typically focused on higher initial concentrations. After 100 d, significant residuals of both TCC and TCS occurred under all conditions and first-order degradation half-lives indicated TCC was more resistant to biodegradation. The estimated K(d) and K(oc) values were 193-296 L kg(-1) and 18175-33991 L kg(-1) for TCC and 33-55 L kg(-1) and 3968-6310 L kg(-1) for TCS. The resulting leaching models indicated these chemicals have a very low leaching potential and are thus unlikely to contaminate groundwater.

Physiological effects and bioconcentration of triclosan on amphibian larvae

We examined the acute effects of triclosan (TCS) exposure, a common antimicrobial found as a contaminant in the field, on survival and physiology of amphibian larvae. LC50 values were determined after 96h for North American larval species: Acris crepitans blanchardii, Bufo woodhousii woodhousii, Rana sphenocephala, and for a developmental model: Xenopus laevis. Amphibian larvae were most sensitive to TCS exposure during early development based upon 96-h LC50 values. Heart rates for X. laevis and North American larvae exposed to TCS were variable throughout development. Metabolic rates of X. laevis and R. sphenocephala larvae exposed to TCS were significantly affected in larvae exposed to [50% LC50] and [LC50]. Tissue uptake and tissue bioconcentration factor (BCF) of TCS were investigated in X. laevis, B. woodhousii woodhousii, and R. sphenocephala. In general, a significant increase was observed as exposure concentration increased. Tissue BCF values were dependent upon stage and species. While TCS concentrations used here are higher than environmental concentrations, exposure to TCS was dependent upon species and developmental stage, with early developmental stages being most sensitive to TCS exposure.

Simultaneous determination and assessment of 4-nonylphenol, bisphenol A and triclosan in tap water, bottled water and baby bottles

This study investigated the levels of 4-nonylphenol (4-NP), bisphenol A (BPA) and triclosan (TCS) in bottled water and tap water in Guangzhou and release of these chemicals from baby bottles using gas chromatography-mass spectrometry with negative chemical ionization. Results show that 4-NP was present in all the bottled water while 17 out of 21 contained BPA and 18 out of 21 contained TCS. Their concentrations in bottled water ranged from 108 to 298 ng/L, 17.6 to 324 ng/L and 0.6 to 9.7 ng/L, respectively. Five of the tap water samples from six drinking water plants were found to contain 4-NP and BPA both in June and December, while TCS was detected in the same five plants only in June. The highest concentrations in tap water for 4-NP, BPA and TCS were 1987, 317 and 14.5ng/L, respectively. Daily intakes of 4-NP, BPA and TCS of adults by drinking 2L of tap water were estimated to be 1410, 148 and 10 ng/day, respectively. BPA was found to be released within 24h from four brands of baby bottles at room temperature (24 degrees C), 40 degrees C and 100 degrees C. Increased temperature led to higher release of BPA from the baby bottles. Estimated daily intakes of 4-NP, BPA and TCS for infants were 705, 1340 and 5 ng/day, respectively, by drinking 1L of tap water from a baby bottle at 40 degrees C. This study showed that the exposure to the three compounds from drinking water is unlikely to pose a health risk.

Probabilistic risk evaluation for triclosan in surface water, sediments, and aquatic biota tissues

Triclosan, an antimicrobial compound used in personal care products, occurs in the aquatic environment due to residual concentrations in municipal wastewater treatment effluent. We evaluate triclosan-related risks to the aquatic environment, for aquatic and sediment-dwelling organisms and for aquatic-feeding wildlife, based on measured and modeled exposure concentrations. Triclosan concentrations in surface water, sediment, and biota tissue are predicted using a fugacity model parameterized to run probabilistically, to supplement the limited available measurements of triclosan in sediment and tissue. Aquatic toxicity is evaluated based on a species sensitivity distribution, which is extrapolated to sediment and tissues assuming equilibrium partitioning. A probabilistic wildlife exposure model is also used, and estimated doses are compared with wildlife toxicity benchmarks identified from a review of published and proprietary studies. The 95th percentiles of measured and modeled triclosan concentrations in surface water, sediment, and biota tissues are consistently below the 5th percentile of the respective species sensitivity distributions, indicating that, under most scenarios, adverse affects due to triclosan are unlikely.

Probabilistic application of a fugacity model to predict triclosan fate during wastewater treatment

The fate and partitioning of the antimicrobial compound, triclosan, in wastewater treatment plants (WWTPs) is evaluated using a probabilistic fugacity model to predict the range of triclosan concentrations in effluent and secondary biosolids. The WWTP model predicts 84% to 92% triclosan removal, which is within the range of measured removal efficiencies (typically 70% to 98%). Triclosan is predominantly removed by sorption and subsequent settling of organic particulates during primary treatment and by aerobic biodegradation during secondary treatment. Median modeled removal efficiency due to sorption is 40% for all treatment phases and 31% in the primary treatment phase. Median modeled removal efficiency due to biodegradation is 48% for all treatment phases and 44% in the secondary treatment phase. Important factors contributing to variation in predicted triclosan concentrations in effluent and biosolids include influent concentrations, solids concentrations in settling tanks, and factors related to solids retention time. Measured triclosan concentrations in biosolids and non-United States (US) effluent are consistent with model predictions. However, median concentrations in US effluent are over-predicted with this model, suggesting that differences in some aspect of treatment practices not incorporated in the model (e.g., disinfection methods) may affect triclosan removal from effluent. Model applications include predicting changes in environmental loadings associated with new triclosan applications and supporting risk analyses for biosolids-amended land and effluent receiving waters.

Occurrence, efficacy, metabolism, and toxicity of triclosan

Triclosan has broad-spectrum anti-microbial activity against most gram-negative and gram-positive bacteria. It is widely used in personal care products, household items, medical devices, and clinical settings. Due to its extensive use, there is potential for humans in all age groups to receive life-time exposures to triclosan, and, indeed, triclosan has been detected in human tissues and the environment. Data gaps exist regarding the chronic dermal toxicity and carcinogenicity of triclosan, which is needed for the risk assessment of triclosan. The US Food and Drug Administration (FDA) nominated triclosan to the National Toxicology Program (NTP) for toxicological evaluations. Currently, the NTP is conducting several dermal toxicological studies to determine the carcinogenic potential of triclosan, evaluate its endocrine and developmental-reproductive effects, and investigate the potential UV-induced dermal formation of chlorinated phenols and dioxins of triclosan. This paper reviews data on the human exposure, environmental fate, efficacy of anti-microbial activity, absorption, distribution, metabolism and elimination, endocrine disrupting effects, and toxicity of triclosan.

Dioxin photoproducts of triclosan and its chlorinated derivatives in sediment cores

Triclosan, a widely used antimicrobial, is known to undergo phototransformation in aqueous solution to form 2,8-dichlorodibenzo-p-dioxin (2,8-DCDD). Two sediment cores from a wastewater-impacted depositional zone of the Mississippi River were analyzed for triclosan by ultra performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS-Q(3)) and for a suite of polychlorinated dioxins and furans by high resolution gas chromatography-mass spectrometry (HRGC-MS) to provide evidence of this photoreaction in the environment. 2,8-DCDD was detected at levels that trended with the historical use of triclosan since its introduction in the 1960s. Three other dioxin congeners, 2,3,7-TCDD, 1,2,8-TriCDD, and 1,2,3,8-TCDD, which are known photoproducts of chlorinated derivatives of triclosan, were also detected with similar trend profiles. These four congeners comprised the majority of di- through tetra-chlorinated dioxins. The trend profile of these specific dioxin congeners did not correlate with the trend profile of the higher-chlorinated dioxin homologues or any chlorinated furan homologues, suggesting a unique source. These results are fully consistent with the phototransformation of triclosan and its chlorinated derivatives that form during wastewater chlorine disinfection as the source of 2,8-DCDD, 2,3,7-TriCDD, 1,2,8-TriCDD, and 1,2,3,8-TCDD in this aquatic environment. As the levels of triclosan-derived dioxins increased over time and the total level of chlorinated dioxins decreased, the contribution of triclosan-derived dioxins to the total dioxin pool increased to as high as 31% by mass in recent years, indicating that their contribution to total dioxin toxicity may need consideration.

Stir-bar-sorptive extraction and ultra-high-performance liquid chromatography-tandem mass spectrometry for simultaneous analysis of UV filters and antimicrobial agents in water samples

Stir-bar-sorptive extraction (SBSE) with liquid desorption (LD) and ultra-high-performance liquid chromatography-electrospray ionization triple-quadrupole tandem mass spectrometry (UHPLC-(ESI)MS-MS) were used for analysis of six personal care products in environmental water: four UV filters (2,2-dihydroxy-4-methoxybenzophenone, benzophenone-3, octocrylene, and octyldimethyl-p-aminobenzoic acid) and two antimicrobial agents (triclocarban and triclosan). Experimental conditions that affect SBSE-LD sorption efficiency (extraction time and temperature, sample pH, and ionic strength) and desorption efficiency (solvent, temperature, and time) were optimized. The method proved to be sensitive--a 50-mL sample was used to determine these compounds in environmental waters at trace levels. The detection limits of the analytical method were 2.5 ng L(-1) for river water and 5-10 ng L(-1) for effluent and influent sewage water. In river waters, benzophenone-3 was found at levels from 6 ng L(-1) to 28 ng L(-1) and triclosan at levels <LOQ. Benzophenone-3 was found between 75 and 127 ng L(-1) in influent sewage, whereas concentrations of benzophenone-3 and triclosan were commonly below 25 ng L(-1) in effluent sewage.

Quantitative gene monitoring of microbial tetracycline resistance using magnetic luminescent nanoparticles

A magnetic/luminescent nanoparticles (MLNPs) based DNA hybridization method was developed for quantitative monitoring of antibiotic resistance genes and gene-expression in environmental samples. Manipulation of magnetic field enabled the separation of the MLNPs-DNA hybrids from the solution and the fluorescence of MLNPs normalized the quantity of target DNA. In our newly developed MLNPs-DNA assay, linear standard curves (R(2) = 0.99) of target gene was determined with the detection limit of 620 gene copies. The potential risk of increased bacterial antibiotic resistance was assessed by quantitative monitoring of tetracycline resistance (i.e., tetQ gene) in wastewater microcosms. The gene abundance and its expression showed a significant increase of tetQ gene copies with the addition of tetracycline, triclosan (TCS), or triclocarban (TCC). A real-time PCR assay was employed to verify the quantification capability of the MLNPs-DNA assay and accordingly both assays have shown strong correlation (R(2) = 0.93). This non-PCR based MLNPs-DNA assay has demonstrated its potential for gene quantification via a rapid, simple, and high throughput platform and its novel use of internal calibration standards.

Fate of triclosan in agricultural soils after biosolid applications

Triclosan (5-chloro-2-[2,4-dichloro-phenoxy]-phenol (TCS) is an antimicrobial compound that is added to a wide variety of household and personal care products. The consumer use of these products releases TCS into urban wastewater and this compound ends up in the environment when agricultural land is fertilized with wastewater biosolids. This study examines the occurrence of TCS in biosolids and its fate in biosolid-treated soils. TCS levels in biosolids generated from one repeatedly-sampled wastewater treatment plant averaged 15.6 + or - 0.6 mg kg(-1) dry wt. (mean + or - standard error) with a slight increase from 2005 to 2007. Surface soil samples were collected from several farms in northern Virginia, US that had received no biosolids, one biosolid application or multiple biosolid applications since 1992. Farm soils that received one application presented TCS concentrations between 4.1 and 4.5 ng g(-1) dry wt. when time since application was over 16 months and between 23.6 and 66.6 ng g(-1) dry wt. for farms where sampling time after application was less than a year. Our results suggest that TCS content of biosolids are rapidly dissipated (estimated half-life of 107.4 d) when applied to agricultural fields. Statistical differences were found (p<0.05) for residual build-up of TCS between multiple-application farms (at least 480 d after application) and controls suggesting that there was a slight build-up of TCS, although the concentrations for these farms were low (<10 ng g(-1) dry wt.).

Transformation of Triclosan by Fe(III)-saturated montmorillonite

Abiotic transformation of triclosan (TCS) was investigated by incubating TCS with Fe(III)- and Na-montmorillonite at 40% relative humidity and room temperature for up to 100 days. The TCS transformation products were characterized using LC/MS, GC/MS, and computational modeling and quantified using HPLC/UV and GC/MS. Within 1-5 days, depending on the initial TCS concentrations, about 55% of the TCS was rapidly transformed in the presence of Fe(III)-montmorillonite, producing 2,4-dichlorophenol, 3-chlorophenol, 2,4-dichlorophenol dimer, chlorophenoxy phenols, and TCS dimers and trimers. Computational modeling based on density functional theory confirmed the formation of four TCS dimer conformers and six TCS trimer conformers. The TCS phenoxy radicals, produced by Fe(III) oxidation of TCS, react with other TCS molecules to form TCS dimers. The TCS trimers were formed by attachment of TCS dimer phenoxy radicals, produced by Fe(III) oxidation of TCS dimers, with TCS molecules. Significantly smaller quantities of TCS transformation products were detected in the reactions with Na-montmorillonite compared to the reactions with Fe(III)-montmorillonite. Formation of a significant amount of 2,4-dichlorophenol, especially in reaction with Fe(III)-montmorillonite, may have negative impact on the environment because of its toxicity. However, mineral-facilitated TCS polymerization may reduce its mobility and bioavailability in soils.

Chemicals of emerging concern in the Great Lakes Basin: an analysis of environmental exposures

This review and statistical analysis was conducted to better understand the nature and significance of environmental exposures in the Great Lakes Basin and watershed to a variety of environmental contaminants. These contaminants of interest included current-use pesticides, pharmaceuticals, organic wastewater contaminants, alkylphenol ethoxylates, perfluorinated surfactants, flame retardants, and chlorinated paraffins. The available literature was critically reviewed and used to develop a database containing 19,611 residue values for 326 substances. In many papers, sampling locations were characterized as being downstream from municipal wastewater discharges, receiving waters for industrial facilities, areas susceptible to agricultural or urban contamination, or harbors and ports. To develop an initial assessment of their potential ecological significance, the contamination levels found were compared with currently available regulatory standards, guidelines, or criteria. This review was prepared for the IJC multi-board work group, and served as background material for an expert consultation, held in March, 2009, in which the significance of the contaminants found was discussed. Moreover, the consultation attempted to identify and assess opportunities for strengthening future actions that will protect the Great Lakes. Based on the findings and conclusions of the expert consultation, it is apparent that a wide variety of chemicals of emerging concern have been detected in environmental media (air, water, sediment, biota) from the Great Lakes Basin, although many are present at only trace levels. Although the presence of these contaminants raises concerns in the public and among the scientific community, the findings must be placed in context. Significant scientific interpretation is required to understand the extent to which these chemicals may pose a threat to the ecosystem and to human health. The ability to detect chemicals in environmental media greatly surpasses our ability to understand the implications of such findings. As advances in analytical technologies occur, it is probable that substances previously found to be non-detectable will be detected. However, their presence in environmental media should not be construed to mean that they are necessarily toxic or hazardous. Current-use pesticides are tightly regulated and extensive efforts have been made to analyze for their presence in surface waters from the Great Lakes Basin. The concentrations found in surface waters for many of the pesticides are below current regulatory criteria. However, the concentrations of certain pesticides exceeded current criteria in 6-32% of the samples analyzed. Detectable concentrations of pharmaceutical compounds were present in 34% of the surface water samples. Various prescription and non-prescription drugs were detected, most frequently at locations that were proximate to the point of discharge from wastewater treatment plants or agricultural operations. At present, there are no standards, guidelines, or criteria with which to compare these contaminant concentrations. Concentrations of alkylphenol ethoxylates and their metabolites have been well studied. All surface water nonylphenol concentrations were below US ambient water quality criteria. However, the concentrations reported for some locations exceeded Canadian guidelines for water or sediment. Only limited data were available for a wide variety of organic wastewater contaminants. Measured concentrations in Great Lakes waters were generally low. Where criteria exist for comparison, the concentrations found were generally below the associated regulatory standards. However, exceedences were noted for some classes of compounds, including phthalates and polycyclic aromatic hydrocarbons. The highest environmental concentrations were reported in biota for a number of persistent, bioaccumulative, and toxic compounds (e.g., polybrominated diphenyl ethers, perfluorinated surfactants). Various stewardship as well as government risk assessment and risk management programs have been implemented over the past years for many of these compounds. Because risk management strategies for some of these contaminants have been implemented only recently, their impact on environmental concentrations, to date, remains unclear. Current evidence suggests that the concentrations of some brominated flame retardants are trending downward, while the concentrations of others appear to be increasing. Regulatory criteria are not available for many of the chemicals of emerging concern that were detected in the Great Lakes Basin. When criteria do exist, it is important to recognize that they were developed based on the best available science at the time. As the science evolves, regulatory criteria must be reassessed in light of new findings (e.g., consideration of new endpoints and mechanisms of action). Further, there are significant scientific gaps in our ability to interpret environmental monitoring data, including the need for: (a) improving the understanding of the effects of mixtures, (b) information on use of, and the commercial life cycle of chemicals and products that contain them, (c) information on source contributions and exposure pathways, and (d) the need for thoughtful additional regulatory,environmental, and health criteria. Discharges from wastewater treatment plants were identified as an important source of contaminants to surface waters in the Great Lakes Basin. Combined sewer overflows and agricultural operations were also found to be important contributors to concentrations in surface waters. Concentrations of many of the chemicals were generally the highest in the vicinity of these sources, decline with increasing distance from sources, and were generally low or non-detectable in the open waters of the Great Lakes.

Impact of biosolids on the persistence and dissipation pathways of triclosan and triclocarban in an agricultural soil

The broad spectrum antimicrobial agents triclosan (TCS) and triclocarban (TCC) are widely used in many personal care products. Knowledge concerning the fate of these two compounds in different environmental matrices is scarce. In this study, the fate of TCS and TCC in soil following direct addition, or when residues were applied via either liquid municipal biosolids (LMB) or dewatered municipal biosolids (DMB) was investigated in laboratory dissipation experiments and under outdoor conditions using radioisotope methods. In laboratory incubations, (14)C-TCC or (14)C-TCS was added to microcosms containing a loam soil and the rate of (14)CO(2) accumulation and loss of solvent-extractable (14)C were determined during incubation at 30 degrees C. Compared to when TCC or TCS was added directly to soil, both chemicals were mineralized more rapidly when applied in LMB, and both were mineralized more slowly when applied in DMB. The application matrix had no effect on the rate of removal of extractable residues. In field experiments, parent compounds were incorporated directly in soil, incorporated via LMB, or a single aggregate of amended DMB was applied to the soil surface. During the experiment soil temperatures ranged from 20 degrees C to 10 degrees C. Dissipation was much slower in the field than in the laboratory experiments. Removal of non-extractable residues was faster in the presence of LMB than the other treatments. Recovery of extractable and non-extractable residues suggested that there was little atmospheric loss of (14)C. Triclocarban readily formed non-extractable residues with DMB whereas TCS did not. Overall, this study has identified that both the pathways and the kinetics of TCS and TCC dissipation in soil are different when the chemicals are carried in biosolids compared to when these chemicals are added directly to the soil.

Spectrophotometric determination of triclosan in personal care products

A spectrophotometric method for the determination of triclosan in personal care products was proposed. It was based on the reaction of sodium nitrite with p-sulfanilic acid in an acidic medium to form diazonium ion, with which triclosan further formed an azo compound in an alkaline medium. The resulting yellow colored product has a maximum absorption at 452 nm. A good linear relationship (r=0.9999) was obtained in the range of 0-30 mg L(-1) triclosan. A detection limit of 0.079 gL(-1) was achieved and the relative standard deviation was 0.24% (n=11) at 14 mg L(-1) triclosan. The proposed method has been applied to the analyses of triclosan in several personal care products and the results were in good agreement with those obtained by high-performance liquid chromatography.

Occurrence of triclosan in plasma of wild Atlantic bottlenose dolphins (Tursiops truncatus) and in their environment

The presence of triclosan, a widely-used antibacterial chemical, is currently unknown in higher trophic-level species such as marine mammals. Blood plasma collected from wild bottlenose dolphins (Tursiops truncatus) in Charleston, SC (CHS) (n = 13) and Indian River Lagoon, FL (IRL) (n = 13) in 2005 was analyzed for triclosan. Plasma concentrations in CHS dolphins ranged from 0.12 to 0.27 ng/g wet weight (mean 0.18 ng/g), with 31% of the sampled individuals having detectable triclosan. The mean IRL dolphin plasma concentrations were 0.072 ng/g wet weight (range 0.025-0.11 ng/g); 23% of the samples having detectable triclosan. In the CHS area, triclosan effluent values from two WWTP were both 190 ng/L and primary influents were 2800 ng/L and 3400 ng/L. Triclosan values in CHS estuarine surface water samples averaged 7.5 ng/L (n = 18) ranging from 4.9 to 14 ng/L. This is the first study to report bioaccumulation of anthropogenic triclosan in a marine mammal highlighting the need for further monitoring and assessment.

Cytotoxic and genotoxic effects of in vitro exposure to triclosan and trimethoprim on zebra mussel (Dreissena polymorpha) hemocytes

Pharmaceuticals and personal care products (PPCPs) have been detected in several aquatic ecosystems for a number of years, but the potential for biological effects in exposed non-target organisms is only now being reported. In this study the potential cellular damage due to two of the main PPCPs found in aquatic environments was investigated by in vitro exposures. Hemolymph samples of the freshwater bivalve Dreissena polymorpha were collected and treated with increasing concentrations of the antibacterial agent Triclosan (TCS) and the antibiotic Trimethoprim (TMP). Doses selected for TCS were 0.1, 0.15, 0.2, and 0.3 microM, while 0.2, 1, and 5 microM for TMP exposures, respectively. We evaluated the potential genotoxicity on hemocytes by the SCGE (single cell gel electrophoresis) assay and apoptosis frequency evaluation, while the cytotoxicity was measured by the lysosomal membranes stability test (NRRA, neutral red retention assay). TCS genotoxicity increased in a dose-dependent manner and this pharmaceutical significantly affects hemocyte functionality due to severe DNA injuries at very low doses. In contrast, TMP seems to be less dangerous than TCS for D. polymorpha because the cytotoxic and the moderate genotoxic effects noticed were obtained only at very high concentration levels.

The partitioning of Triclosan between aqueous and particulate bound phases in the Hudson River Estuary

The distribution of Triclosan within the Hudson River Estuary can be explained by a balance among the overall effluent inputs from municipal sewage treatment facilities, dilution of Triclosan concentrations in the water column with freshwater and seawater inputs, removal of Triclosan from the water column by adsorption to particles, and loss to photodegradation. This study shows that an average water column concentration of 3+/-2 ng/l (in the lower Hudson River Estuary) is consistent with an estimate for dilution of average wastewater concentrations with seawater and calculated rates of adsorption of Triclosan to particles. An average Triclosan sediment concentration of 26+/-11 ng/g would be in equilibrium with the overlying water column if Triclosan has a particle-to-water partitioning coefficient of k(d) approximately 10(4), consistent with laboratory estimates.

Adsorption and degradation of triclosan and triclocarban in soils and biosolids-amended soils

Triclosan and triclocarban are antibacterial agents that are widely used in numerous personal care products. Limited information is available on their environmental behavior in soils and soils land applied with wastewaters and biosolids. In this study, laboratory experiments were performed to investigate their adsorption and degradation in soils. Both antibacterial agents adsorbed strongly to the sandy loam and silty clay soils with and without addition of biosolids, with distribution coefficients (K(d)) ranging from 178 to 264 L kg(-1) for triclosan and from 763 to 1187 L kg(-1) for triclocarban. Sorption of triclosan decreased with increase in soil pH from 4 to 8, whereas triclocarban sorption showed no effect within the tested pH range. Competitive sorption was observed when triclosan and triclocarban coexisted, but the cosolute effect was concentration dependent. Biosolids amendment increased the sorption of triclosan and triclocarban, likely due to the addition of soil organic matter, but displayed no significant effect on degradation.

Detection of the antimicrobials triclocarban and triclosan in agricultural soils following land application of municipal biosolids

The occurrence of the antimicrobials triclocarban (TCC) and triclosan (TCS) was investigated in agricultural soils following land application of biosolids using liquid chromatography-tandem mass spectrometry (LC-MS-MS) with negative ion multimode ionization. The method detection limits were 0.58 ng TCC/g soil, 3.08 ng TCC/g biosolids, 0.05 ng TCS/g soil and 0.11 ng TCS/g biosolids and the average recovery from all of the sample matrices was >95%. Antimicrobial concentrations in biosolids from three Michigan wastewater treatment plants (WWTPs) ranged from 4890 to 9280 ng/g, and from 90 to 7060 ng/g, for TCC and TCS respectively. Antimicrobial analysis of soil samples, collected over two years, from ten agricultural sites previously amended with biosolids, indicated TCC was present at higher concentrations (1.24-7.01 ng/g and 1.20-65.10 ng/g in 2007 and 2008) compared to TCS (0.16-1.02 ng/g and from the method detection limit, <0.05-0.28 ng/g in 2007 and 2008). Soil antimicrobial concentrations could not be correlated to any soil characteristic, or to the time of last biosolids application, which occurred in either 2003, 2004 or 2007. To our knowledge, our data represent the first report of TCC, and the first comparison of TCC and TCS concentrations, in biosolids-amended agricultural soils. Such information is important because approximately 50% of US biosolids are land applied, therefore, any downstream effects of either antimicrobial are likely to be widespread.

Biodegradation of pharmaceutical and personal care products

Medical treatments and personal hygiene lead to the steady release of pharmaceutical and personal care products (PPCPs) into the environment. Some of these PPCPs have been shown to have detrimental environmental effects and could potentially impact human health. Understanding the biological transformation of PPCPs is essential for accurately determining their ultimate environmental fate, conducting accurate risk assessments, and improving PPCP removal. We summarize the current literature concerning the biological transformation of PPCPs in wastewater treatment plants, the environment, and by pure cultures of bacterial isolates. Although some PPCPs, such as ibuprofen, are readily degraded under most studied conditions, others, such as carbamazepine, tend to be recalcitrant. This variation in the biodegradability of PPCPs can be attributed to structural differences, because PPCPs are classified by application, not chemical structure. The degradation pathways of octylphenol by Sphingomonas sp. strain PWE1, ibuprofen by Sphingomonas sp. strain Ibu-2, and DEET by Pseudomonas putida DTB are discussed in more detail.