Biological degradation of triclocarban and triclosan in a soil under aerobic and anaerobic conditions and comparison with environmental fate modelling

Comparison of degradation between indigenous and spiked bisphenol A and triclosan in a biosolids amended soil

This study compared the degradation of indigenous bisphenol A (BPA) and triclosan (TCS) in a biosolids-amended soil, to the degradation of spiked labelled surrogates of the same compounds (BPA-d16 and TCS-(13)C12). The aim was to determine if spiking experiments accurately predict the degradation of compounds in biosolids-amended soils using two different types of biosolids, a centrifuge dried biosolids (CDB) and a lagoon dried biosolids (LDB). The rate of degradation of the compounds was examined and the results indicated that there were considerable differences between the indigenous and spiked compounds. These differences were more marked for BPA, for which the indigenous compound was detectable throughout the study, whereas the spiked compound decreased to below the detection limit prior to the study completion. The rate of degradation for the indigenous BPA was approximately 5-times slower than that of the spiked BPA-d16. The indigenous and spiked TCS were both detectable throughout the study, however, the shape of the degradation curves varied considerably, particularly in the CDB treatment. These findings show that spiking experiments may not be suitable to predict the degradation and persistence of organic compounds following land application of biosolids.

Triclosan exposure alters postembryonic development in a Pacific tree frog (Pseudacris regilla) Amphibian Metamorphosis Assay (TREEMA)

The Amphibian Metamorphosis Assay (AMA), developed for Xenopus laevis, is designed to identify chemicals that disrupt thyroid hormone (TH)-mediated biological processes. We adapted the AMA for use on an ecologically-relevant North American species, the Pacific tree frog (Pseudacris regilla), and applied molecular endpoints to evaluate the effects of the antibacterial agent, triclosan (TCS). Premetamorphic (Gosner stage 26-28) tadpoles were immersed for 21 days in solvent control, 1.5 μg/L thyroxine (T(4)), 0.3, 3 and 30 μg/L (nominal) TCS, or combined T(4)/TCS treatments. Exposure effects were scored by morphometric (developmental stage, wet weight, and body, snout-vent and hindlimb lengths) and molecular (mRNA abundance using quantitative real time polymerase chain reaction) criteria. T(4) treatment alone accelerated development concomitant with altered levels of TH receptors α and β, proliferating cell nuclear antigen, and gelatinase B mRNAs in the brain and tail. We observed TCS-induced perturbations in all of the molecular and morphological endpoints indicating that TCS exposure disrupts coordination of postembryonic tadpole development. Clear alterations in molecular endpoints were evident at day 2 whereas the earliest morphological effects appeared at day 4 and were most evident at day 21. Although TCS alone (3 and 30 μg/L) was protective against tadpole mortality, this protection was lost in the presence of T(4). The Pacific tree frog is the most sensitive species examined to date displaying disruption of TH-mediated development by a common antimicrobial agent.

Effects of monorhamnolipid and dirhamnolipid on sorption and desorption of triclosan in sediment-water system

The effects of monorhamnolipid (RL-F1) and dirhamnolipid (RL-F2) on the sorption and desorption of triclosan (TCS) in sediment-water system were investigated in this study. Results of the bath equilibrium experiments showed that RL-F2 provided much higher solubilization enhancement for TCS than RL-F1. Sorption of both rhamnolipids by the sediments was highly correlated with the sediment clay content. Moreover, the apparent distribution coefficients of TCS K(d)(*) decreased with the increase of rhamnolipid concentration (0.05-7.5 mM), and RL-F2 presented a larger distribution capacity of TCS into the aqueous phase at relatively higher concentrations (>2.5 mM). Further results also indicated that the release of TCS from sediment could be enhanced by both rhamnolipids. RL-F2 was more efficient than RL-F1 in desorbing TCS from the sediment with low clay content. The TCS desorption percentages R(d)(*) of RL-F2 (5mM) was 1.8-2.4 times that of RL-F1. These findings could provide useful guidelines for the application of rhamnolipid-enhanced remediation technologies for TCS contaminated sediment.

Phytoaccumulation of antimicrobials by hydroponic Cucurbita pepo

Consumer use of antimicrobial-containing products continuously introduces triclocarban and triclosan into the environment. Triclocarban and triclosan adversely affect plants and animals and have the potential to affect human health. Research examined the phytoaccumulation of triclocarban and triclosan by pumpkin (Cucurbita pepo cultivar Howden) and zucchini (Cucurbita pepo cultivar Gold Rush) grown hydroponically. Pumpkin and zucchini were grown in nutrient solution spiked with 0.315 microg/mL triclocarban and 0.289 microg/mL triclosan for two months. Concentrations of triclocarban and triclosan in nutrient solutions were monitored weekly. At the end of the trial, roots and shoots were analyzed for triclocarban and triclosan. Research demonstrated that pumpkin and zucchini accumulated triclocarban and triclosan. Root accumulation factors were 1.78 and 0.64 and translocation factors were 0.001 and 0.082 for triclocarban and triclosan, respectively. The results of this experiment were compared with a previous soil column study that represented environmentally relevant exposure of antimicrobials from biosolids and had similar root mass. Plants were not as efficient in removing triclocarban and triclosan in hydroponic systems as in soil systems. Shoot concentrations of antimicrobials were the same or lower in hydroponic systems than in soil columns, indicating that hydroponic system does not overpredict the concentrations of antimicrobials.

Evaluation of triclosan and triclocarban at river basin scale using monitoring and modeling tools: implications for controlling of urban domestic sewage discharge

Triclosan (TCS) and triclocarban (TCC) are two commonly used personal care products. They may enter into aquatic environments after consumption and pose potential risks to aquatic organisms. We investigated the occurrence and fate of TCS and TCC in five large rivers (the Liao River, Hai River, Yellow River, Zhujiang River and Dongjiang River) in China, and compared the monitoring data with the predicted results from Level III fugacity modeling. TCS and TCC were detected in the five large rivers with the detection frequencies of 100% or close to 100% in surface water and sediments of almost every river. TCS and TCC were found at concentrations of up to 478 ng/L and 338 ng/L in surface water, and up to 1329 ng/g and 2723 ng/g in sediments. Cluster analysis indicated that the sites with higher concentrations were usually located in or near urban area. Meanwhile, principal component analysis also suggested that the mass inventories of TCS and TCC in water and sediment were significantly influenced by the factors such as the total or untreated urban domestic sewage discharge at river basin scale. The concentrations and mass inventories from the fugacity modeling were found at the same order of magnitude with the measured values, suggesting that the fugacity modeling can provide a useful tool for evaluating the fate of TCS and TCC in riverine environments. Both monitoring and modeling results indicated that the majority of mass inventories of TCS and TCC were stored into sediment, which could be a potential pollution source for river water. The wide presence of TCS and TCC in these large rivers of China implies that better controlling of urban domestic sewage discharge is needed.

Transfer of wastewater associated pharmaceuticals and personal care products to crop plants from biosolids treated soil

The plant uptake of emerging organic contaminants such as pharmaceuticals and personal care products (PPCPs) is receiving increased attention. Biosolids from municipal wastewater treatment have been previously identified as a major source for PPCPs. Thus, plant uptake of PPCPs from biosolids applied soils needs to be understood. In the present study, the uptake of carbamazepine, diphenhydramine, and triclocarban by five vegetable crop plants was examined in a field experiment. At the time of harvest, three compounds were detected in all plants grown in biosolids-treated soils. Calculated root concentration factor (RCF) and shoot concentration factor (SCF) are the highest for carbamazepine followed by triclocarban and diphenhydramine. Positive correlation between RCF and root lipid content was observed for carbamazepine but not for diphenhydramine and triclocarban. The results demonstrate the ability of crop plants to accumulate PPCPs from contaminated soils. The plant uptake processes of PPCPs are likely affected by their physico-chemical properties, and their interaction with soil. The difference uptake behavior between plant species could not solely be attributed to the root lipid content.

Removal of trace organic chemicals in onsite wastewater soil treatment units: a laboratory experiment

Onsite wastewater treatment is used by 20% of residences in the United States. The ability of these systems, specifically soil treatment units (STUs), to attenuate trace organic chemicals (TOrCs) is not well understood. TOrCs released by STUs pose a potential risk to downstream groundwater and hydraulically-connected surface water that may be used as a drinking water source. A series of bench-scale experiments were conducted using sand columns to represent STUs and to evaluate the efficacy of TOrC attenuation as a function of hydraulic loading rate (1, 4, 8, 12, and 30 cm/day). Each hydraulic loading rate was examined using triplicate experimental columns. Columns were initially seeded with raw wastewater to establish a microbial community, after which they were fed with synthetic wastewater and spiked with 17 TOrCs, in four equal doses per day, to provide a consistent influent water quality. After an initial start-up phase, effluent from all columns consistently demonstrated >90% reductions in dissolved organic carbon and nearly complete (>85%) oxidation of ammonia to nitrate, comparable to the performance of field STUs. The results of this study suggest STUs are capable of attenuating many TOrCs present in domestic wastewater, but attenuation is compound-specific. A subset of TOrCs exhibited an inverse relationship with hydraulic loading rate and attenuation efficiency. Atenolol, cimetidine, and TCPP were more effectively attenuated over time in each experiment, suggesting that the microbial community evolved to a stage where these TOrCs were more effectively biotransformed. Aerobic conditions as compared to anaerobic conditions resulted in more efficient attenuation of acetaminophen and cimetidine.

Biological effects of environmentally relevant concentrations of the pharmaceutical Triclosan in the marine mussel Perna perna (Linnaeus, 1758)

Triclosan (5-Chloro-2-(2,4-dichlorophenoxy) phenol) is an antibacterial compound widely employed in pharmaceuticals and personal care products. Although this emerging compound has been detected in aquatic environments, scarce information is found on the effects of Triclosan to marine organisms. The aim of this study was to evaluate the toxicity of a concentration range of Triclosan through fertilization assay (reproductive success), embryo-larval development assay (early life stage) and physiological stress (Neutral Red Retention Time assay - NRRT) (adult stage) in the marine sentinel organism Perna perna. The mean inhibition concentrations for fertilization (IC(50) = 0.490 mg L(-1)) and embryo-larval development (IC(50) = 0.135 mg L(-1)) tests were above environmental relevant concentrations (ng L(-1)) given by previous studies. Differently, significant reduction on NRRT results was found at 12 ng L(-1), demonstrating the current risk of the continuous introduction of Triclosan into aquatic environments, and the need of ecotoxicological studies oriented by the mechanism of action of the compound.

The effect of triclosan on microbial community structure in three soils

The application of sewage sludge to land can expose soils to a range of associated chemical toxicants. In this paper we explore the effects of the broad spectrum anti-microbial compound triclosan on the phenotypic composition of the microbial communities of three soils of contrasting texture (loamy sand, sandy loam and clay) using phospholipid fatty-acid (PLFA) analysis. Each soil type was dosed and subsequently re-dosed 6 weeks later with triclosan at five nominal concentrations in microcosms (10, 100, 500, 1000 mg kg(-1) and a zero-dose control). PLFA profiles were analysed using multivariate statistics focussing on changes in the soil phenotypic community structure. Additionally, ratios of fungal:bacterial PLFA indicators and cyclo:mono-unsaturated PLFAs (a common stress indicator) were calculated. It was hypothesised that triclosan addition would alter the community structure in each soil with a particular effect on the fungal:bacterial ratio, since bacteria are likely to be more susceptible to triclosan than fungi. It was also hypothesised that the PLFA response to re-dosing would be suppressed due to acclimation. Although the microbial community structure changed over the course of the experiment, the response was complex. Soil type and time emerged as the most important explanatory factors. Principal component analysis was used to detect phenotypic responses to different doses of triclosan in each soil. As expected, there was a significant increase in the fungal:bacterial ratio with triclosan dose especially in treatments with the highest nominal concentrations. Furthermore, the PLFA response to re-dosing was negligible in all soils confirming the acclimation hypothesis.

Fate of triclosan in field soils receiving sewage sludge

The anti-microbial substance triclosan can partition to sewage sludge during wastewater treatment and subsequently transfer to soil when applied to land. Here, we describe the fate of triclosan in a one-year plot experiment on three different soils receiving sludge. Triclosan and methyl-triclosan concentrations were measured in soil samples collected monthly from three depths. A large fraction of triclosan loss appeared to be explained by transformation to methyl-triclosan. After 12 months less than 20% of the initial triclosan was recovered from each soil. However, the majority was recovered as methyl-triclosan. Most of the chemical recovered at the end of the experiment (both triclosan and methyl-triclosan) was still in the top 10 cm layer, although there was translocation to lower soil horizons in all three soils. Between 16.5 and 50.6% of the applied triclosan was unaccounted for after 12 months either as a consequence of degradation or the formation of non-extractable residues.

Bioconcentration of triclosan, methyl-triclosan, and triclocarban in the plants and sediments of a constructed wetland

Constructed wetlands are a potential method for the removal of two pharmaceutical and personal care products from wastewater effluent. Triclosan (TCS; 5-chloro-2-[2,4-dichlorophenoxy]phenol) and triclocarban (TCC; 3,4,4'-trichlorocarbanillide) are antimicrobial agents added to a variety of consumer products whose accumulation patterns in constructed wetlands are poorly understood. Here, we report the accumulation of TCS, its metabolite methyl-triclosan (MTCS; 5-chloro-2-[2,4-dichlorophenoxy]), and TCC in wetland plant tissues and sediments. Three wetland macrophytes: Typha latifolia, Pontederia cordata, and Sagittaria graminea were sampled from a constructed wetland in Denton, Texas, USA. MTCS concentrations were below the method detection limit (MDL) for all species. TCS root tissue concentrations in T. latifolia were significantly greater than root concentrations in P. cordata (mean±SE in ng g(-1): 40.3±11.3 vs. 15.0±1.9, respectively), while for TCC, shoot tissue concentrations in S. graminea were significantly greater than in T. latifolia (22.8±9.3 vs. 9.0 (MDL), respectively). For both TCS and TCC, T. latifolia root tissue concentrations were significantly greater than shoot concentrations (TCS: 40.3±11.3 vs. 17.2±0.2, TCC: 26.0±3.6 vs. 9.0, (MDL)). TCC concentrations in P. cordata roots were significantly greater than in shoots (34.4±5.3 vs. 15.4±2.8, respectively). TCS concentrations in T. latifolia roots and sediments and TCC concentrations in sediments generally decreased from wetland inflow to outflow. To our knowledge, this is the first study documenting species and tissue specific differences in the accumulation of TCS and TCC in plants from an operational constructed wetland. The species specific differences in bioaccumulation suggest TCS and TCC removal from constructed wetlands could be enhanced through targeted plantings.

Biochemical and genotoxic effect of triclosan on earthworms (Eisenia fetida) using contact and soil tests

Triclosan (TCS) is a broad-spectrum bactericide that is used for a variety of antimicrobial functions. TCS is frequently detected in the terrestrial environment due to application of sewage sludge to agricultural land. In the present study, 48-h paper contact and 28-day spiked soil tests were conducted to examine the toxic effects of TCS on the antioxidative and genetic indices of earthworms (Eisenia fetida). The activity of antioxidative enzymes (superoxide dismutase, SOD; catalase, CAT) and the content of the lipid peroxidation product (malondialdehyde, MDA) were determined as biomarkers of oxidative stress in E. fetida. Moreover, single cell gel electrophoresis (SCGE) was used as a biomarker of genotoxicity. The results showed that triclosan induced a significant increase (P < 0.05) in antioxidative enzyme activities and MDA content. Of all of the biomarkers examined, CAT activity was most sensitive to TCS, and the CAT activity increased significantly (P < 0.05) at bactericidal concentrations of 7.86 ng cm⁻² in the contact test and 10 mg kg⁻¹ in the spiked soil test. The comet assay showed that TCS treatments significantly induced (P < 0.05) DNA damage in E. fetida, and that 78.6 ng cm⁻² caused significant genotoxic effects in the acute test (48 h). Clear dose-dependent DNA damage to E. fetida was observed both in contact and spiked soil tests. These results imply that TCS may have potential biochemical and genetic toxicity toward earthworms (E. fetida). A battery of biomarkers covering multiple molecular targets of acute toxicity can be combined to better understand the impacts of TCS on E. fetida.

Analysis of emerging organic contaminants in environmental solid samples

Spreading sewage sludge on agricultural lands has been actively promoted by national authorities as an economic way of recycling. However, as by-product of wastewater treatment, sewage sludge may contain toxic substances, which could be incorporated into agricultural products or be distributed in the environment. Moreover, sediments can be contaminated by the discharge of wastewater effluents into rivers. This article reviews the determination of emerging contaminants (surfactants, flame retardants, pharmaceuticals and personal care products) in environmental solid samples (sludge, soil and sediment). Sample preparation, including extraction and clean-up, as well as the subsequent instrumental determination of contaminants are discussed. Recent applications of extraction techniques, such as Soxhlet extraction, ultrasound assisted extraction, pressurised liquid extraction, microwave assisted extraction and matrix solid-phase dispersion to the analysis of emerging contaminants in environmental solid samples are reviewed. Determination of these contaminants, generally carried out by gas chromatography and liquid chromatography coupled with different detectors, especially mass spectrometry for the identification and quantification of residues, is also summarised and discussed.

Effect of biostimulation on community level physiological profiles of microorganisms in field-scale biopiles composed of aged oil sludge

Four biopiles were constructed for the bioremediation of total petroleum hydrocarbons (TPHs) in aged oily sludge by indigenous microorganisms. Three biopiles were treated with bulking agent, nutrients or their combination with the fourth pile serving as the control. Responses of microbial community level physiological profiles (CLPPs) to these biostimulation strategies were estimated, and variances among three layers within each biopile were evaluated. Microbial metabolic activity and diversity and the numbers of two species of bacteria were significantly enhanced by the addition of bulking agent, which also made the layers more homogeneous. In contrast, the application of large amounts of nutrients had a suppressing effect on the microbes. After 220 days, 49.62% of TPHs were removed from the middle layer of the bulking agent pile, whereas only 20.44% were removed from the inner layer of the control. This study aims to provide experience to improve the remediation efficiency of future investigations.

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).

OCCURRENCE

Because of its partial elimination in sewage treatment plants, most reports describe TCS as one of the most commonly encountered substances in solid and water environmental compartments. It has been detected in a microgram per liter or microgram per kilogram level in sewage treatment plants (influents, effluents, and sludges), natural waters (rivers, lakes, and estuarine waters), and sediments as well as in drinking water.

TOXICITY

Moreover, due to its high hydrophobicity, TCS can accumulate in fatty tissues and has been found in fish and human samples (urine, breast milk, and serum). TCS is known to be biodegradable, photo-unstable, and reactive towards chlorine and ozone.

DISCUSSION

As a consequence, it can be transformed into potentially more toxic and persistent compounds, such as chlorinated phenols and biphenyl ethers after chlorination, methyl triclosan after biological methylation, and chlorinated dibenzodioxins after photooxidation. The toxicity of TCS toward aquatic organisms like fish, crustaceans, and algae has been demonstrated with EC50 values near TCS environmental concentrations. It has even been shown to produce cytotoxic, genotoxic, and endocrine disruptor effects.

CONCLUSION

Furthermore, the excessive use of TCS is suspected to increase the risk of emergence of TCS-resistant bacteria and the selection of resistant strains.

Pharmaceutical and personal care products in groundwater, subsurface drainage, soil, and wheat grain, following a high single application of municipal biosolids to a field

Dewatered municipal biosolids (DMBs) were applied to a field at a rate of ~22 Mg dw ha(-1) in October 2008. Pharmaceuticals and personal care products (PPCPs) were monitored in groundwater, tile drainage, soil, DMB aggregates incorporated into the soil post-land application, and in the grain of wheat grown on the field for a period of ~1 year following application. Over 80 PPCPs were analyzed in the source DMB. PPCPs selected for in-depth monitoring included: antibiotics (tetracyclines, fluoroquinolones), bacteriocides (triclosan, triclocarban), beta-blockers (atenolol, propranolol, metaprolol), antidepressants (fluoxetine, citalopram, venlafaxine, sertraline), antifungals (miconazole), analgesics (acetaminophen, ibuprofen) and anticonvulsants (carbamazepine). PPCPs in tile were observed twice, ~3 weeks and 2 months post-application. Of all PPCPs measured in tile drainage, only carbamazepine, ibuprofen, acetaminophen, triclosan, triclocarban, venlafaxine, and citalopram were detected (5-74 ng L(-1)). PPCPs were not detected in groundwater >2 m depth below the soil surface, and concentrations above detection limits at 2 m depth were only observed once just after the first rain event post-application. In groundwater, all compounds found in tile, except carbamazepine, acetaminophen and citalopram, were detected (10-19 ng L(-1)). PPCPs were detected in DMB aggregates incorporated in soil up to 1 year post-application, with miconazole and fluoxetine having the lowest percent reductions over 1 year (~50%). For several compounds in these aggregates, concentration declines were of exponential decay form. No PPCPs were detected in the grain of wheat planted post-application on the field. No PPCPs were ever detected in water, soil or grain samples from the reference plot, where no DMB was applied.

Field dissipation of 4-nonylphenol, 4-t-octylphenol, triclosan and bisphenol A following land application of biosolids

The persistence of contaminants entering the environment through land application of biosolids needs to be understood to assess the potential risks associated. This study used two biosolids treatments to examine the dissipation of four organic compounds: 4-nonylphenol, 4-t-octylphenol, bisphenol A and triclosan, under field conditions in South Australia. The pattern of dissipation was assessed to determine if a first-order or a biphasic model better described the data. The field dissipation data was compared to previously obtained laboratory degradation data. The concentrations of 4-nonylphenol, 4-t-octylphenol and bisphenol A decreased during the field study, whereas the concentration of triclosan showed no marked decrease. The time taken for 50% of the initial concentration of the compounds in the two biosolids to dissipate (DT50), based on a first-order model, was 257 and 248 d for 4-nonylphenol, 231 and 75 d for 4-t-octylphenol and 289 and 43 d for bisphenol A. These field DT50 values were 10- to 20-times longer for 4-nonylphenol and 4-t-octylphenol and 2.5-times longer for bisphenol A than DT50 values determined in the laboratory. A DT50 value could not be determined for triclosan as this compound showed no marked decrease in concentration. The biphasic model provided a significantly improved fit to the 4-t-octylphenol data in both biosolids treatments, however, for 4-nonylphenol and bisphenol A it only improved the fit for one treatment. This study shows that the use of laboratory experiments to predict field persistence of compounds in biosolids amended soils may greatly overestimate degradation rates and inaccurately predict patterns of dissipation.

Occurrence, fate, and persistence of gemfibrozil in water and soil

Pharmaceuticals and personal care products (PPCPs) have emerged as a group of potential environmental contaminants of concern. The occurrence of gemfibrozil, a lipid-regulating drug, was studied in the influent and effluent at a wastewater treatment plant (WWTP) and groundwater below a land application site receiving treated effluent from the WWTP. In addition, the sorption of gemfibrozil in two loam soils and sand was assessed, and biological degradation rates in two soil types under aerobic conditions were also determined. Results showed that concentrations of gemfibrozil in wastewater influent, effluent, and groundwater were in the range of 3.47 to 63.8 µg/L, 0.08 to 19.4 µg/L, and undetectable to 6.86 µg/L, respectively. Data also indicated that gemfibrozil in the wastewater could reach groundwater following land application of the treated effluent. Soil-water distribution coefficients for gemfibrozil, determined by the batch equilibrium method, varied with organic carbon content in the soils. The sorption capacity was silt loam > sandy loam > sand. Under aerobic conditions, dissipation half-lives for gemfibrozil in sandy loam and silt loam soils were 17.8 and 20.6 days, respectively; 25.4 and 11.3% of gemfibrozil was lost through biodegradation from the two soils over 14 days.

Degradation of triclosan under aerobic, anoxic, and anaerobic conditions

Triclosan (2, 4, 4'-trichloro-2'-hydroxyl diphenyl ether) is a broad-spectrum antimicrobial agent present in a number of house hold consumables. Aerobic and anaerobic enrichment cultures tolerating triclosan were developed and 77 bacterial strains tolerating triclosan at different levels were isolated from different inoculum sources. Biodegradation of triclosan under aerobic, anoxic (denitrifying and sulphate reducing conditions), and anaerobic conditions was studied in batch cultures with isolated pure strains and enrichment consortium developed. Under aerobic conditions, the isolated strains tolerated triclosan up to 1 g/L and degraded the compound in inorganic-mineral-broth and agar media. At 10 mg/L level triclosan, 95 ± 1.2% was degraded in 5 days, producing phenol, catechol and 2, 4-dichlorophenol as the degradation products. The strains were able to metabolize triclosan and its degradation products in the presence of monooxygenase inhibitor 1-pentyne. Under anoxic/anaerobic conditions highest degradation (87%) was observed in methanogenic system with acetate as co-substrate and phenol, catechol, and 2, 4-dichlorophenol were among the products. Three of the isolated strains tolerating 1 g/L triclosan were identified as Pseudomonas sp. (BDC 1, 2, and 3).

Fate of triclosan and triclocarban in soil columns with and without biosolids surface application

The leaching and transformation behaviors of triclosan (TCS) and triclocarban (TCC) in soil columns (20 cm high, 4 cm in diameter) packed with an agricultural soil (Roxana very fine sandy loam) with and without biosolids surface application were investigated. The column leachates and soil samples were analyzed for TCS, TCC, and their transformation products. Significantly more TCS was transformed compared with TCC. Surface application of biosolids significantly retarded their transformation. Downward movement of TCS and TCC occurred within a 10-cm soil depth. Methyl-TCS was not detectable in the leachates but was detected in the top 5-cm soil layer, with more appearing in the biosolids-applied soil. At the end of the column study, carbanilide (CBA) was the only detectable TCC reductive dechlorination product in the soil. No TCC reductive dechlorination products were detectable in the leachates. Detection of 3,4-dichloroaniline (3,4-DCA) and 4-chloroaniline (4-CA) suggested the occurrence of TCC hydrolysis. Rapid leaching of 4-CA through the soil column was observed. The 3,4-DCA was detected throughout the entire 20-cm depth of the soil column but not in the leachates. The fact that only small percentages of the transformed TCS and TCC appeared, after a 101-d column study, in the forms of the products analyzed suggested that either the investigated transformation pathways were minor pathways or further rapid transformation of those products had occurred.

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.

Phytoaccumulation of antimicrobials from biosolids: impacts on environmental fate and relevance to human exposure

Triclocarban and triclosan, two antimicrobials widely used in consumer products, can adversely affect ecosystems and potentially impact human health. The application of biosolids to agricultural fields introduces triclocarban and triclosan to soil and water resources. This research examined the phytoaccumulation of antimicrobials, effects of plant growth on migration of antimicrobials to water resources, and relevance of phytoaccumulation in human exposure to antimicrobials. Pumpkin, zucchini, and switch grass were grown in soil columns to which biosolids were applied. Leachate from soil columns was assessed every other week for triclocarban and triclosan. At the end of the trial, concentrations of triclocarban and triclosan were determined for soil, roots, stems, and leaves. Results indicated that plants can reduce leaching of antimicrobials to water resources. Pumpkin and zucchini growth significantly reduced soil concentrations of triclosan to less than 0.001 mg/kg, while zucchini significantly reduced soil concentrations of triclocarban to 0.04 mg/kg. Pumpkin, zucchini, and switch grass accumulated triclocarban and triclosan in mg per kg (dry) concentrations. Potential human exposure to triclocarban from consumption of pumpkin or zucchini was substantially less than exposure from product use, but was greater than exposure from drinking water consumption. Consequently, research indicated that pumpkin and zucchini may beneficially impact the fate of antimicrobials in agricultural fields, while presenting minimal acute risk to human health.

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.

Determination of preservative and antimicrobial compounds in fish from Manila Bay, Philippines using ultra high performance liquid chromatography tandem mass spectrometry, and assessment of human dietary exposure

Ultra high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) determination of four paraben preservatives (methyl, ethyl, propyl and butyl) and two antimicrobial agents (triclosan and triclocarban) belonging to personal care products (PCPs) in 20 species of fish from Manila Bay (Philippines) was performed. Detection of PCPs with greater frequency indicates the ubiquitous contamination of Manila Bay. Concentrations of total paraben were one order of magnitude higher than the antimicrobials in almost all fish, except in Stolephorus indicus and Leiognathus equulus. A positive correlation was observed between parabens concentration and fish length (r = 0.31-0.49; p<0.05 to <0.001) and fish weight (r = 0.28-0.49; p<0.05 to <0.001), but not for the antimicrobials. The estimated dietary exposure values of the four parabens in the Philippines through fish is four orders of magnitude lower than the acceptable daily intake (ADI) of 10mg/kg/day, but the values of antimicrobials are just half of the ADI of TCS. To our knowledge, this is the first report of PCPs contamination in fish from Philippines.

Degradation of 4-nonylphenol, 4-t-octylphenol, bisphenol A and triclosan following biosolids addition to soil under laboratory conditions

Land application of biosolids is common practice in many countries, however, there are some potential risks associated with the presence of contaminants within the biosolids. This laboratory study examined the degradation of four commonly found organic compounds, 4-nonylphenol, 4-t-octylphenol, bisphenol A, and triclosan, in soil following the addition of two biosolids over 32 weeks. The pattern of degradation was assessed to determine if it followed a standard first-order decay model or if a biphasic model with a degrading and a recalcitrant fraction better described the data. The time taken for the initial concentrations to decrease by 50% (DT50), based on a first-order model, was 12-25 d for 4-nonylphenol, 10-14 d for 4-t-octylphenol, 18-102 d for bisphenol A, and 73-301 d for triclosan. For 4-nonylphenol, bisphenol A and triclosan, the biphasic model fitted the degradation data better than the first-order model, indicating the presence of a degrading fraction and a non-degrading recalcitrant fraction. The recalcitrant fraction for these three compounds at the completion of the 32 week experiment was 17-21%, 24-42%, and 30-51% of the initial concentrations, respectively. For 4-t-octylphenol, the first-order model was sufficient in explaining the degradation data, indicating that no recalcitrant fraction was present. This study showed that biphasic degradation occurred for some organic compounds in biosolids amended soil and that the use of standard first-order degradation models may underestimate the persistence of some organic compounds following land application of biosolids.

Uptake of 17α-ethynylestradiol and triclosan in pinto bean, Phaseolus vulgaris

Pharmaceuticals and personal care products (PPCPs) have emerged as a group of potential environmental contaminants of concern. PPCPs in soil may enter terrestrial food webs via plant uptake. We evaluated uptake of 17α-ethynylestradiol (EE2) and triclosan in bean plants (Phaseolus vulgaris) grown in sand and soil. The extent of uptake and accumulation of EE2 and triclosan in plants grown in sand was higher than in plants grown in soil. In sand (conditions of maximum contaminant bioavailability), bioconcentration factors (BCFs) of EE2 and triclosan in roots (based on dry weights) were 1424 and 16,364, respectively, whereas BCFs in leaves were 55 for EE2 and 85 for triclosan. In soil, the BCF of EE2 decreased from 154 in the first week to 32 in the fourth week while it fluctuated in leaves from 18 to 20. The BCF for triclosan in plants grown in soil increased over time to 12 in roots and 8 in leaves. These results indicate that the potential for uptake and accumulation of PPCPs in plants exists. This trophic transfer pathway should be considered when assessing exposure to certain PPCPs, particularly with the use of recycled wastewater for irrigation.

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.

Inhibition of soluble epoxide hydrolase contributes to the anti-inflammatory effect of antimicrobial triclocarban in a murine model

The increasing use of the antimicrobial triclocarban (TCC) in personal care products (PCPs) has resulted in concern regarding environmental pollution. TCC is a potent inhibitor of soluble epoxide hydrolase (sEH). Inhibitors of sEH (sEHIs) are anti-inflammatory, anti-hypertensive and cardio-protective in multiple animal models. However, the in vivo effects anticipated from a sEHI have not been reported for TCC. Here we demonstrated the anti-inflammatory effects in vivo of TCC in a murine model. TCC was employed in a lipopolysaccharide (LPS)-challenged murine model. Systolic blood pressure, plasma levels of several inflammatory cytokines and chemokine, and metabolomic profile of plasma oxylipins were determined. TCC significantly reversed LPS-induced morbid hypotension in a time-dependent manner. TCC significantly repressed the increased release of inflammatory cytokines and chemokine caused by LPS. Furthermore, TCC significantly shifted the oxylipin profile in vivo in a time-dependent manner towards resolution of inflammation as expected from a sEHI. These results demonstrated that at the doses used TCC is anti-inflammatory in the murine model. This study suggests that TCC may provide some benefits in humans in addition to its antimicrobial activities due to its potent inhibition of sEH. It may be a promising starting point for developing new low volume high value applications of TCC. However these biological effects also caution against the general over use of TCC in PCPs.

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.

Dual-resolution molecular dynamics simulation of antimicrobials in biomembranes

Triclocarban and triclosan, two potent antibacterial molecules present in many consumer products, have been subject to growing debate on a number of issues, particularly in relation to their possible role in causing microbial resistance. In this computational study, we present molecular-level insights into the interaction between these antimicrobial agents and hydrated phospholipid bilayers (taken as a simple model for the cell membrane). Simulations are conducted by a novel 'dual-resolution' molecular dynamics approach which combines accuracy with efficiency: the antimicrobials, modelled atomistically, are mixed with simplified (coarse-grain) models of lipids and water. A first set of calculations is run to study the antimicrobials' transfer free energies and orientations as a function of depth inside the membrane. Both molecules are predicted to preferentially accumulate in the lipid headgroup-glycerol region; this finding, which reproduces corresponding experimental data, is also discussed in terms of a general relation between solute partitioning and the intramembrane distribution of pressure. A second set of runs involves membranes incorporated with different molar concentrations of antimicrobial molecules (up to one antimicrobial per two lipids). We study the effects induced on fundamental membrane properties, such as the electron density, lateral pressure and electrical potential profiles. In particular, the analysis of the spontaneous curvature indicates that increasing antimicrobial concentrations promote a 'destabilizing' tendency towards non-bilayer phases, as observed experimentally. The antimicrobials' influence on the self-assembly process is also investigated. The significance of our results in the context of current theories of antimicrobial action is discussed.

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.

Distribution and accumulation of endocrine-disrupting chemicals and pharmaceuticals in wastewater irrigated soils in Hebei, China

This study investigated the occurrence of 43 emerging contaminants including 9 endocrine-disrupting chemicals and 34 pharmaceuticals in three sites in Hebei Province, north China. Each site has a wastewater irrigated plot and a separate groundwater irrigated plot for comparison purpose. The results showed that the concentrations of the target compounds in the wastewater irrigated soils were in most cases higher than those in the groundwater irrigated soils. Among the 43 target compounds, nine compounds bisphenol-A, triclocarban, triclosan, 4-nonylphenol, salicylic acid, oxytetracycline, tetracycline, trimethoprim and primidone were detected at least once in the soils. Preliminary environmental risk assessment showed that triclocarban might pose high risks to terrestrial organisms while the other detected compounds posed minimal risks. Irrigation with wastewater could lead to presence or accumulation of some emerging contaminants to some extent in irrigated soils.

Effect of Fe-Pd bimetallic nanoparticles on Sphingomonas sp. PH-07 and a nano-bio hybrid process for triclosan degradation

In this study, we have evaluated the effect of palladium-iron bimetallic nanoparticles (nFe-Pd) on diphenyl ether (DE) degrading bacterial strain Sphingomonas sp. PH-07 as well as a sequential nano-bio hybrid process with nFe-Pd as catalytic reductant and PH-07 as biocatalyst for degradation of triclosan. Strain PH-07 grew well in the presence of nFe-Pd up to 0.1g/L in minimal salts medium with DE as carbon source. In aqueous system, TCS (17.3 μM) was completely dechlorinated within 2h by nFe-Pd (0.1g/L) with concomitant release of 2-phenoxyphenol (16.8 μM) and chloride ions (46 μM). All possible dichloro- and monochloro-2-phenoxyphenol intermediates were identified by HPLC and GC-MS analyses, and the dechlorination pathway was proposed. Addition of PH-07 cells into the reactor effectively degraded the 2-phenoxyphenol. Our results reveal that strain PH-07 survives well in the presence of nFe-Pd and nFe-Pd/PH-07 hybrid treatment could be a potential strategy for degradation of TCS.

Persistence of triclocarban and triclosan in soils after land application of biosolids and bioaccumulation in Eisenia foetida

The presence of the antimicrobial chemicals triclocarban (TCC) and triclosan (TCS) in municipal biosolids has raised concerns about the potential impacts of these chemicals on soil ecosystems following land application of municipal biosolids. The relative persistence of TCC and TCS in agricultural fields receiving yearly applications of biosolids at six different loading rates over a three-year period was investigated. Soil and biosolids samples were collected, extracted, and analyzed for TCC and TCS using liquid chromatography-tandem mass spectrometry. In addition, the potential for bioaccumulation of TCC and TCS from the biosolids-amended soils was assessed over 28 d in the earthworm Eisenia foetida. Standard 28-d bioaccumulation tests were conducted for three biosolids loading rates from two sites, representing agronomic and twice the agronomic rates of biosolids application plots as well as control plots receiving no applications of biosolids. Additional bioaccumulation kinetic data were collected for the soils receiving the high biosolids loadings to ensure attainment of quasi steady-state conditions. The results indicate that TCC is relatively more persistent in biosolids-amended soil than TCS. In addition, TCC bioaccumulated in E. foetida, reaching body burdens of 25 ± 4 and 133 ± 17 ng/g(ww) in worms exposed for 28 d to the two soils amended with biosolids at agronomic rates. The 28-d organic carbon and lipid-normalized biota soil accumulation factors (BSAFs) were calculated for TCC and ranged from 0.22 ± 0.12 to 0.71 ± 0.13. These findings suggest that TCC bioaccumulation is somewhat consistent with the traditional hydrophobic organic contaminant (HOC) partitioning paradigm. However, these data also suggest substantially reduced bioavailability of TCC in biosolids-amended soils compared with HOC partitioning theory.

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.

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.

Accumulation and leaching potential of some pharmaceuticals and potential endocrine disruptors in soils irrigated with wastewater in the Tula Valley, Mexico

The reuse of wastewater for irrigation of agricultural land is a well established practice but introduces many contaminants into the terrestrial environment including pharmaceuticals and personal care products. This study reports the persistence and leaching potential of a group of acidic pharmaceuticals, carbamazepine, and three endocrine disruptors in soils from the Tula Valley in Mexico, one of the largest irrigation districts in the world that uses untreated wastewater. After irrigation of soil columns with fortified wastewater over the equivalent of one crop cycle, between 0% and 7% of the total added amounts of ibuprofen, naproxen, and diclofenac and between 0% and 25% of 4-nonylphenol, triclosan, and bisphenol-A were recovered from the soil profiles. Carbamazepine was more persistent, between 55% and 107% being recovered. Amounts in leachates suggested that movement through the soil was possible for all of the analytes, particularly in profiles of low organic matter and clay content. Analysis of soil samples from the Tula Valley confirmed the general lack of accumulation of the acidic pharmaceuticals (concentrations from below the limit of detection to 0.61 μgkg(-1)) and endocrine disruptors (concentrations from below the limit of detection to 109 μgkg(-1)) despite continual addition through regular irrigation with untreated wastewater; there was little evidence of movement through the soil profiles. In contrast, carbamazepine was present in horizon A of the soil at concentrations equivalent to several years of additions by irrigation (2.6-7.5 μgkg(-1)) and was also present in the deeper horizons. The persistence and mobility of carbamazepine suggested a potential to contaminate groundwater.

Identification of wastewater bacteria involved in the degradation of triclocarban and its non-chlorinated congener

Triclocarban (TCC) is an antimicrobial additive of personal care products that is only partially degraded during wastewater treatment. Bacteria responsible for its transformation are unknown. We obtained wastewater bacteria capable of using as the sole carbon source TCC or its non-chlorinated analog, carbanilide (NCC). Enrichments established using activated sludge amended with TCC and NCC, respectively, were maintained for 1 year through successive transfers. Enrichments displayed exponential growth after 2 weeks, reaching stationary phase after 1 month. The NCC enrichment was shown to accumulate aniline. Denaturing gradient gel electrophoresis of amplified 16S rRNA genes indicated markedly reduced community richness compared to the inoculum and a single, prominent taxonomic unit emerged in both chlorinated and non-chlorinated carbanilide enrichment cultures. Cloned 16S rRNA genes showed both enrichments were dominated by a single genotype related to uncharacterized organisms within the Alcaligenaceae. Of ∼30 sequences from each enrichment, no other organisms were detected in the TCC enrichment while, a small, flanking community of alpha proteobacteria was detected in the NCC enrichment. Study results demonstrate that growth of wastewater bacteria on TCC and its lower chlorinated analog can be linked to bacteria within the family Alcaligenaceae. These organisms are promising agents for the bioremediation of hazardous phenylurea pollutants.

Potential biochemical and genetic toxicity of triclosan as an emerging pollutant on earthworms (Eisenia fetida)

Triclosan as an important antimicrobial agent is increasingly detected in the terrestrial environment as sewage sludge and reclaimed water are applied on land, but little is known about its effect on non-target soil organisms. In this study, biochemical responses including changes in the activity of catalase (CAT), superoxide dismutase (SOD), glutathione-S-transferase (GST), and malondialdehyde (MDA) of the earthworm Eisenia fetida were examined in order to assess ecological toxicity of the chemical. The single-cell gel electrophoresis (SCGE) was also used to measure the potential genotoxicity of the chemical. The results showed that the activity of CAT and GST at the highest tested dose could be stimulated after a 2-d exposure, reaching 148% and 123% of that in the control, respectively. However, with prolonged exposure, the activity of CAT and GST at the highest tested dose was inhibited, falling to 47% and 33% of that in the control, respectively. Triclosan induced an increase in the activity of SOD, but no significant (p>0.05) changes were observed. The content of MDA was dependent both on the dose of triclosan and on the exposure duration. The comet assay demonstrated that triclosan treatments led to a dose-dependent DNA damage of E. fetida after exposures of 7 and 14 d. Our findings can suggest that triclosan has sublethal effects on E. fetida.

Rapid resolution liquid chromatography-tandem mass spectrometry method for the determination of endocrine disrupting chemicals (EDCs), pharmaceuticals and personal care products (PPCPs) in wastewater irrigated soils

A multiresidue analytical method was developed for the determination of 9 endocrine disrupting chemicals (EDCs) and 19 pharmaceuticals and personal care products (PPCPs) including acidic and neutral pharmaceuticals in water and soil samples using rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS). Solid phase extraction (SPE), and ultrasonic extraction combined with silica gel purification were applied as pretreatment methods for water and soil samples, respectively. The extracts of the EDCs and PPCPs in water and soil samples were then analyzed by RRLC-MS/MS in electrospray ionization (ESI) mode in three independent runs. The chromatographic mobile phases consisted of Milli-Q water and acetonitrile for EDCs and neutral pharmaceuticals, and Milli-Q water containing 0.01 % acetic acid (v/v) and acetonitrile: methanol (1:1, v/v) for acidic pharmaceuticals at a flow rate of 0.3 mL/min. Most of the target compounds exhibited signal suppression due to matrix effects. Measures taken to reduce matrix effects included use of isotope-labeled internal standards, and application of matrix-match calibration curves in the RRLC-MS/MS analyses. The limits of quantitation ranged between 0.15 and 14.08 ng/L for water samples and between 0.06 and 10.64 ng/g for solid samples. The recoveries for the target analytes ranged from 62 to 208 % in water samples and 43 to 177 % in solid samples, with majority of the target compounds having recoveries ranging between 70–120 %. Precision, expressed as the relative standard deviation (RSD), was obtained less than 7.6 and 20.5 % for repeatability and reproducibility, respectively. The established method was successfully applied to the water and soil samples from four irrigated plots in Guangzhou. Six compounds namely bisphenol-A, 4-nonylphenol, triclosan, triclocarban, salicylic acid and clofibric acid were detected in the soils.

Aquatic hazard assessment for pharmaceuticals, personal care products, and endocrine-disrupting compounds from biosolids-amended land

Reuse of biosolids on agricultural land is a common practice. Following the application of biosolids to land, contaminants in the biosolids have the potential to migrate offsite via surface runoff and/or leaching and pose a hazard to aquatic ecosystems. The aim of this screening-level assessment study was to determine the relative hazard posed to aquatic ecosystems by pharmaceuticals, personal care products, and endocrine-disrupting compounds (EDCs) that have been detected and quantified in biosolids. This involved estimating maximum possible runoff water concentrations of compounds, using an equilibrium partitioning approach and then comparing these with the lowest available aquatic toxicity data, using the hazard quotient (HQ) approach. A total of 45 pharmaceuticals, personal care products, and EDCs have been detected in biosolids. Ten of these compounds (tonalide, galaxolide, 17β-estradiol, 17α-ethinylestradiol, ciprofloxacin, doxycycline, norfloxacin, ofloxacin, triclosan, and triclocarban) posed a high (HQ >1.0) hazard to aquatic ecosystems relative to the other compounds. This hazard assessment indicated that further research into potential offsite migration and deleterious effects on aquatic ecosystems is warranted for the 10 organic contaminants identified, and possibly for chemicals with similar physicochemical and toxicological properties, in biosolids-amended soils. Because many antibiotic compounds (e.g., ciprofloxacin, norfloxacin, and ofloxacin) have ionic properties, the methods used may have overestimated their predicted aqueous concentrations and hazard. Further research that includes site-specific variables, e.g., dilution factors in waterways, rain intensity, slope of land, degradation, and the use of management strategies such as buffer zones, is likely to decrease the hazard posed by these high hazard compounds.

Retention-release characteristics of triclocarban and triclosan in biosolids, soils, and biosolids-amended soils

Transport models that incorporate retention/release characteristics of organic compounds in soils and sediments typically assume that organic-carbon normalized partition coefficients (K(OC)) apply to all solid matrices and that the partitioning process is completely reversible. Partition coefficients (K(d)) (from which the K(OC) was calculated), and retention/release characteristics of triclocarban (TCC) and triclosan (TCS) in biosolids, soils, and biosolids-amended soils were determined. Four soils of different physicochemical properties amended with biosolids at 10 g/kg, together with unamended soils, and several biosolids were separately spiked with either [(14)C]TCC or [(14)C]TCS for the various determinations. The hysteresis coefficient values of the two compounds were consistently <1 in all three solid matrices, suggesting strong hysteresis. Multiple desorption steps (24 h each) over several days revealed incomplete desorption of the two compounds from all three solid matrices. The K(d) values determined in biosolids (log K(d) 3.34 +/- 0.13 for TCC and 3.76 +/- 0.39 for TCS) were greater than those determined in soils (log K(d) 1.71 +/- 0.09 for TCC and 2.25 +/- 0.26 for TCS) and biosolids-amended soils (log K(d)1.90 +/- 0.16 for TCC and 2.31 +/- 0.19 for TCS), however, the K(OC) values of all three solid matrices were similar (log K(OC) of 3.82 +/- 0.16 for TCC and 4.26 +/- 0.31 for TCS). Thus, it was concluded that a single or a narrow range of K(OC) values for TCC and TCS may be appropriate to describe retention of the compounds in soils and sediments. However, models that assume complete reversibility of the retention/release processes of the compounds in soils and sediments may not adequately describe the retention/release characteristics of the compounds in soils and sediments, especially when the chemicals are biosolids borne.

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.

Uptake of pharmaceutical and personal care products by soybean plants from soils applied with biosolids and irrigated with contaminated water

Many pharmaceuticals and personal care products (PPCPs) are commonly found in biosolids and effluents from wastewater treatment plants. Land application of these biosolids and the reclamation of treated wastewater can transfer those PPCPs into the terrestrial and aquatic environments, giving rise to potential accumulation in plants. In this work, a greenhouse experiment was used to study the uptake of three pharmaceuticals (carbamazepine, diphenhydramine, and fluoxetine) and two personal care products (triclosan and triclocarban) by an agriculturally important species, soybean (Glycine max (L.) Merr.). Two treatments simulating biosolids application and wastewater irrigation were investigated. After growing for 60 and 110 days, plant tissues and soils were analyzed for target compounds. Carbamazepine, triclosan, and triclocarban were found to be concentrated in root tissues and translocated into above ground parts including beans, whereas accumulation and translocation for diphenhydramine and fluoxetine was limited. The uptake of selected compounds differed by treatment, with biosolids application resulting in higher plant concentrations, likely due to higher loading. However, compounds introduced by irrigation appeared to be more available for uptake and translocation. Degradation is the main mechanism for the dissipation of selected compounds in biosolids applied soils, and the presence of soybean plants had no significant effect on sorption. Data from two different harvests suggest that the uptake from soil to root and translocation from root to leaf may be rate limited for triclosan and triclocarban and metabolism may occur within the plant for carbamazepine.

Occurrence and risks of triclosan and triclocarban in the Pearl River system, South China: from source to the receiving environment

We investigated two commonly used antimicrobial agents triclosan (TCS) and triclocarban (TCC) in the Pearl River system in China (i.e., Liuxi, Zhujiang and Shijing Rivers) and four sewage effluents during dry and wet seasons. The median values for TCS and TCC were the highest in the surface water and sediments of the Shijing River, followed by the Zhujiang River and Liuxi River. Screening level risk assessment using the risk quotient (RQ) method showed that TCS and TCC in surface water posed median risks in the Zhujiang and Liuxi Rivers (RQs: 0.28-0.62 for TCS, and 0.15-0.80 for TCC) and high risks in the Shijing River (RQs: 5.15-9.55 for TCS, and 3.32-5.83 for TCC). Higher risks (RQs: 3.63-28.47 for TCS, and 3.13-24.54 for TCC) were found in the sediments than in surface water of the Pearl River system. The four sewage effluents and Shijing River as well as other urban streams in Guangzhou metropolitan area were identified as the sources of the two compounds in the main river Zhujiang River. The mass inventories of TCS and TCC in the Pearl River system indicate that the sediments are not only an important sink but also a potential source for the two compounds in surface water.