Linuron Research Articles

Endocrine disrupting chemicals in wastewater treatment plants in Kenya, East Africa: Concentrations, removal efficiency, mass loading rates and ecological impacts

This study investigated the levels, mass loadings, removal efficiency, and associated ecotoxicological risks of selected endocrine disrupting chemicals (EDCs), namely, dibutylphthalate (DBP), diethylhexylphthalate (DEHP), dimethylphthalate (DMP), linuron (LNR) and progesterone (PGT) in wastewater, sludge, and untreated dry biosolid (UDBS) samples from twelve wastewater treatment plants (WWTPs) in nine major towns in Kenya. Analysis was done using high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS). All the wastewater influents had quantifiable levels of EDCs with DBP being the most abundant (37.49%) with a range of 4.33 ± 0.63 to 19.68 ± 1.24 μg L−1. DEHP was the most abundant in sludge and accounted for 48.2% ranging between 278.67 and 9243.49 ng g−1 dry weight (dw). In the UDBS samples, DEHP was also the most abundant (40%) of the total EDCs detected with levels ranging from 78.77 to 3938.54 ng g−1 dw. The average removal efficiency per pollutant was as follows: DMP (98.7%) > DEHP (91.7%) > PGT (83.4%) > DBP (77.9%) > LNR (72.2%) which can be attributed to sorption onto the biosolid, biological degradation, photolysis, and phytoremediation. The pH was negatively correlated to the EDC concentrations while total dissolved solids (TDS), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), and electrical conductivity (EC) were positively correlated. The mass loadings were as high as 373.33 g day−1 of DBP in the treatment plants located in densely populated cities. DEHP and PGT had their Risk Quotients (RQs) > 1, posing a high risk to biota. DMP, DBP, and LNR posed medium risks as their RQ values were between 0.1 and 1. EDCs are therefore loaded to environmental compartments through either the effluent that loads these pollutants into the receiving aquatic ecosystem or through the UDBS, which are used as fertilizers in agricultural farmlands causing potential toxicological risks to aquatic and terrestrial life.

Analysis of herbicide and its applications through a sensitive electrochemical technique based on MWCNTs/ZnO/CPE fabricated sensor

The electrochemical performance of linuron (LNR) was studied by fabricating the carbon paste electrode (CPE) using multiwalled carbon nanotubes (MWCNTs) along with zinc oxide (ZnO) nanoparticles (MWCNTs/ZnO/CPE). The influence of electro-kinetic specifications involving steady heterogeneous rate, pH, sweep rate, temperature effect, transfer coefficient, accumulation time, activation energy, as well as the total number of protons and electrons participating in electro-oxidation of LNR has been established using voltammetric techniques like cyclic voltammetry (CV) and square wave voltammetry (SWV). These techniques were applied to investigate LNR in real samples such as soil including water samples. Over the 0.02 μM–0.34 μM ranges, a linear relationship was confirmed along with the limit of detection and quantification (LOD and LOQ) of the LNR. The synthesized ZnO nanoparticles were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD) analysis. The MWCNTs/ZnO/CPE sensor was considered sensitive for LNR detection because the sensor exhibited enhanced catalytic qualities with peak current in the involvement of 0.2 M phosphate buffer solution (PBS) of pH 6.0, attributed to the ultimate sensing performance of the sensor.

Nanostructured graphitic carbon nitride (g-C3N4)-CTAB modified electrode for the highly sensitive detection of amino-triazole and linuron herbicides

In agro-areas, linuron (LNR) and amino-triazole (ATZ) are the widely used herbicides to protect crops, but their widespread use pollutes the environment, especially when these are mixed with water or soil. In efforts to address these environmental issues and to detect trace quantities of the herbicides, a graphitic carbon nitride (g-C3N4) with cetyltrimethylammonium bromide (CTAB) modified carbon paste electrode (g–C3N4–CTAB/CPE) was developed and used for the detection of LNR and ATZ. Materials were characterized by XRD, TEM and AFM techniques. The effect of pH on electro-oxidation (under optimized conditions) showed the maximum peak current at pH of 4.2 for AMT and pH 6.0 for LNR. The electro−kinetic and thermodynamic parameters of LNR and ATZ were determined. Additional experiments were performed for the trace level detection of ATZ and LNR using the square wave voltammetric technique. Concentrations were varied linearly in the range of 3.0 × 10−7 M to 4.5 × 10−5 M for ATZ with a detection limit of 6.41 × 10−8 M, and 1.2 × 10−7 M to 3.0 × 10−4 M for LNR with a detection limit of 2.47 × 10−8 M. The developed novel sensor was effective for trace level detection of LNR and ATZ in water and soil samples.

Highly sensitive electrochemical sensor for the detection and quantification of Linuron based on silica gel modified carbon paste electrode

In this study, the electrochemical efficiency of linuron (LRN) was investigated using carbon paste electrode modified by silica gel (SG/CPE). The voltammetric approaches such as cyclic voltammetry (CV) and square wave voltammetry (SWV) was used to study several electro-kinetic parameters such as heterogeneous rate, temperature influence, transfer coefficient, scan rate, pH, accumulation period, and even the overall number of electrons transferred along with protons engaging in the electro-oxidation of LRN. The fabricated sensor was used to analyze LRN in soil and water samples. The SG/CPE sensor was found to be sensitive for LRN detection due to improved catalytic characteristics to peak current in 6.0 pH phosphate buffer solution (PBS) of ionic strength 0.2 M which contributed to the sensor’s good sensing performance. The peak current was noted to be 26.68μA with peak potential of 1.0886 V for SG/CPE and the peak current is 7.44μA which was noted for the bare carbon paste electrode (BCPE) with the peak potential of 1.0762 V. The limit of detection and quantification of the LRN was determined at 3.94 nM and 13.1 nM respectively. The soil and water samples showed peak potential at 1.0855 V for different concentrations of LRN. The current method found to be a highly sensitive technique for the determination of LRN in real samples.

Investigation of Antimutagenic Effect of <i>Rosa canina</i> L. Against Linuron Induced DNA Damage on Root Meristematic Cells of <i>Allium cepa</i> L.

Investigation of Antimutagenic Effect of <i>Rosa canina</i> L. Against Linuron Induced DNA Damage on Root Meristematic Cells of <i>Allium cepa</i> L.

Maternal exposure to mixtures of dienestrol, linuron and flutamide. Part II: Endocrine-related gene expression assessment on male offspring rat testes

Exposure to endocrine-disrupting compounds (EDCs) during pregnancy and early development can lead to adverse developmental outcomes in offspring. One of the endpoints of concern is feminization. The present study aimed to investigate for any possible correlations with endocrine sensitive parameters in the testes of male rat offspring following dam exposure to three EDCs by assessing the expression of endocrine-related genes. Dienestrol (DIES) [0.37–6.25 μg/kg bw/day], linuron (LIN) [1.5–50 mg/kg bw/day], flutamide (FLU) [3.5–50 mg/kg bw/day] as well as their binary mixtures were administered to sexually mature female rats from gestation day (GD) 6 until postnatal day (PND) 21. Gene expression analysis of Star, Cyp11a1, Cyp17a1, Hsd3b2, Pgr and Insl3 was performed by RT-qPCR. Administration of the anti-androgen FLU alone significantly upregulated Cyp11a1 and Cyp17a1 gene expression while administration of LIN and DIES alone did not alter significantly gene expression. The effects of the binary mixtures on gene expression were not as marked as those seen after single compound administrations. Deregulation of Cyp17a1 in rat pup testis, following administration of FLU alone or in mixtures to dams, was significantly correlated with the observed feminization endpoints in male pups.

Maternal exposure to mixtures of dienestrol, linuron and flutamide. Part I: Feminization effects on male rat offspring

Exposure to endocrine-disrupting compounds (EDCs) during pregnancy can result in negative health effects in later generations, including sex changes and feminization. The present study assessed the feminization effects on male offspring rats of three EDCs: Dienestrol (DIES), Linuron (LIN), and Flutamide (FLU). Sexually mature female rats were exposed from gestation day (GD) 6 until postnatal day (PND) 21 to: 0.37, 0.75, 1.5, 3.12 or 6.25 μg/kg/day of DIES, 1.5, 3, 6, 12.5, 25 or 50 mg/kg/day of LIN, 3.5, 6.7, 12.5, 25 or 50 mg/kg/day of FLU, and the following mixtures: FLU + DIES (mg/kg/day+μg/kg/day), 3.5 + 0.37, or 3.5 + 3, 25 + 0.37, or 25 + 3; FLU + LIN (mg/kg/day + mg/kg/day), 3.5 + 12.5, or 25 + 12.5; and DIES + LIN (μg/kg/day + mg/kg/day), 0.37 + 12.5, or 3 + 12.5. Anogenital distance (AGD), nipple retention (NR) and cryptorchidism were evaluated. FLU produced a decrease of AGD, an increase of NR, and an increase of cryptorchidism at the highest dose. None of these three endpoints were significantly affected by LIN or DIES treatments alone. Combinations of FLU + LIN and FLU + DIES increased NR, and decreased AGD, while DIES + LIN did not produce any effects in male pups. Results show that FLU is able to induce feminization in male pups, while binary combinations of LIN and DIES did not modify the effects produced by FLU.

Electrochemical behavior study of some selected phenylurea herbicides at activated pencil graphite electrode. Electrooxidation of linuron and monolinuron

A novel and rapid voltammetric assay for the simultaneous determination of monolinuron (MLN) and linuron (LIN) using an electrochemically pretreated pencil graphite electrode (PGE*) is reported for the first time. Enhanced oxidation peak currents of MLN and LIN were observed at PGE* when compared with electrochemically non-pretreated PGE. Differential pulse voltammetric (DPV) results showed distinct anodic peaks at 1.064 V and 1.170 V for MLN and LIN, respectively. Under optimum conditions, the detection limits were 3.7 × 10−7 mol L−1 and 5.8 × 10−7 mol L−1 for MLN and LIN respectively. The DPV method was applied for the quantitative determination of the mentioned compounds in spiked tap water samples enriched by solid phase extraction. The voltammetric results were in good agreement with high-performance liquid chromatography data.

Expression of the human gene CYP1A2 enhances tolerance and detoxification of the phenylurea herbicide linuron in Arabidopsis thaliana plants and Escherichia coli

The phenylurea herbicide, linuron (LIN), is used to control various types of weeds. Despite its efficient role in controlling weeds, it presents a persistent problem to the environment. In the current study, phytoremediation properties of transgenic CYP1A2 Arabidopsis thaliana plants to LIN were assessed. CYP1A2 gene was firstly cloned and expressed in bacteria before proceeding to plants. In presence of LIN, The growth of CYP1A2 expressing bacteria was superior compared to control bacteria transformed with the empty bacterial expression vector pET22b(+). No clear morphological changes were detected on CYP1A2 transgenic plants. However, significant resistance to LIN herbicide application either via spraying the foliar parts of the plant or via supplementation of the herbicide in the growth medium was observed for CYP1A2 transformants. Plant growth assays under LIN stress provide strong evidence for the enhanced capacity of transgenic lines to grow and to tolerate high concentrations of LIN compared to control plants. HPLC analyses showed that detoxification of LIN by bacterial extracts and/or transgenic plant leaves is improved as compared to the corresponding controls. Our data indicate that over expression of the human CYP1A2 gene increases the phytoremediation capacity and tolerance of Arabidopsis thaliana plants to the phenylurea herbicide linuron.

Assessment of buffer zone for aquatic organisms in pesticide application

In pesticide applications, the buffer zone helps to protect water sources against pesticide contamination. In 2014, in the Adana province, the percentage of herbicides used was approximately 12% in corn, sunflower, soybean and cotton. To control the weeds, fifteen active ingredients (a.i.) were used in these crops in 2014. These a.i. were acetochlor, aclonifen, benfluralin, bromoxynil, clethodim, dicamba, fluazifop-p-butyl, foramsulfuron, linuron, mesotrione, nicosulfuron, oxyfluorfen, prometryn, trifluralin and tritosulfuron. The aim of this study was to assess the risk of these herbicides on aquatic organisms and estimate buffer zone distances for the above agricultural crops in herbicide application. Risk index (RI) values were calculated according to German Drift Model (GDM) and Dutch Drift Model (DDM). Consequently, buffer zone needs for herbicide application of five a.i., namely acetochlor, benfluralin, linuron, prometryn, and trifluralin, were determined in this study. Results showed that acetochlor a.i. has the highest risk to aquatic organisms and needs a buffer zone distance of more than 57 meters in sunflower cultivation. It was assessed that buffer zone distances should be more than 1.32 m for linuron in soybean, 3.5 m for benfluralin in sunflower, 4.13 m for prometryn (1.5 kg a.i./hm2) in sunflower and 4.19 m for trifluralin in cotton and soybean, and 5.54 m for prometryn (2.0kg a.i./hm2) in cotton. There was no need for a buffer zone in corn. Keywords: buffer zone, pesticide, herbicide, risk index, cotton, sunflower, corn, soybean DOI: 10.3965/j.ijabe.20160905.2364 Citation: Yarpuz-Bozdogan N. Assessment of buffer zone for aquatic organisms in pesticide application. Int J Agric & Biol Eng, 2016; 9(5): 227－234.

Effects of anti-androgens cyproterone acetate, linuron, vinclozolin, and p,p'-DDE on the reproductive organs of the copepod Acartia tonsa

ABSTRACTThe study was performed to detect the effects of anti-androgenic compounds on the reproduction. In this paper alterations observed in the marine calanoid copepod Acartia tonsa exposed to environmental concentrations of cyproterone acetate (CPA), linuron (LIN), vinclozolin (VIN), and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE) for 21 days covering a full life cycle are described. Histological alterations were studied with a focus on reproductive organs, gonad and accessory sexual glands. Exposure to ≥1.2 µg L−1 CPA caused degeneration of spermatocytes and deformation of the spermatophore in males. In a single male exposed to 33 µg L−1 CPA, an ovotestis was observed. In CPA exposed females, enhancement of oogenesis, increase in apoptosis and a decrease in proliferation occurred. Exposure of males to ≥12 µg L−1 LIN caused degenerative effects in spermatogonia, spermatocytes and spermatids, and at 4.7 µg L−1 LIN, the spermatophore wall displayed an irregular formation. In LIN exposed females, no such structural alterations were found; however, the proliferation index was reduced at 29 µg L−1 LIN. At an exposure concentration of ≥100 µg L−1 VIN, distinct areas in male gonad were stimulated, whereas others displayed a disturbed spermatogenesis and a deformed spermatophore wall. In VIN exposed female A. tonsa, no effects were observed. Male A. tonsa exposed to p,p'-DDE displayed an impairment of spermatogenesis in all stages with increased degrees of apoptosis. In p,p'-DDE-exposed females, a statistical significant increase of the proliferation index and an intensification of oogenesis were observed at 0.0088 µg L−1.

Classifying chemical mode of action using gene networks and machine learning: A case study with the herbicide linuron

The herbicide linuron (LIN) is an endocrine disruptor with an anti-androgenic mode of action. The objectives of this study were to (1) improve knowledge of androgen and anti-androgen signaling in the teleostean ovary and to (2) assess the ability of gene networks and machine learning to classify LIN as an anti-androgen using transcriptomic data. Ovarian explants from vitellogenic fathead minnows (FHMs) were exposed to three concentrations of either 5α-dihydrotestosterone (DHT), flutamide (FLUT), or LIN for 12h. Ovaries exposed to DHT showed a significant increase in 17β-estradiol (E2) production while FLUT and LIN had no effect on E2. To improve understanding of androgen receptor signaling in the ovary, a reciprocal gene expression network was constructed for DHT and FLUT using pathway analysis and these data suggested that steroid metabolism, translation, and DNA replication are processes regulated through AR signaling in the ovary. Sub-network enrichment analysis revealed that FLUT and LIN shared more regulated gene networks in common compared to DHT. Using transcriptomic datasets from different fish species, machine learning algorithms classified LIN successfully with other anti-androgens. This study advances knowledge regarding molecular signaling cascades in the ovary that are responsive to androgens and anti-androgens and provides proof of concept that gene network analysis and machine learning can classify priority chemicals using experimental transcriptomic data collected from different fish species.

Hepatic Protein Expression Networks Associated with Masculinization in the Female Fathead Minnow (Pimephales promelas)

Endocrine disruptors that act via the androgen receptor (AR) are less well studied than environmental estrogens, and there is evidence that treatment with AR agonists can result in masculinization of female fish. In this study, female fathead minnows (FHM) were exposed to the model nonaromatizable androgen 5-alpha dihydrotestosterone (DHT) (100 μg/L), the ureic-based herbicide linuron (LIN) (100 μg/L), and a mixture of DHT and LIN (100 μg/L each) to better characterize androgen action in females. LIN was used because of reports that this chemical has an antiandrogenic mode of action in fish. After 21d, DHT and LIN treatments resulted in a significant depression of plasma vitellogenin (Vtg) and DHT and DHT+LIN increased the prevalence of nuptial tubercles in female FHMs indicating masculinization. Using iTRAQ and an LTQ Orbitrap Velos, ∼2000 proteins were identified in the FHM liver and the number of proteins quantified after exposures was >1200. Proteins that significantly and consistently changed in abundance across biological replicates included prostaglandin E synthase 3, programmed cell death 4a, glutathione S transferases, canopy, selenoprotein U, and ribosomal proteins. Subnetwork enrichment analysis identified that interferon and epidermal growth factor signaling were regulated by DHT and LIN, suggesting that these signaling pathways are correlated to depressed plasma vitellogenin. These data provide novel insight into hepatic protein networks that are associated with the process of masculinization in teleosts.

Exposure to the pesticide linuron affects androgen‐dependent gene expression in the three‐spined stickleback (Gasterosteus aculeatus)

Previous research demonstrated that exposure to exogenous androgens and effluents with androgenic activity can induce spiggin mRNA production in the kidney of the three-spined stickleback (Gasterosteus aculeatus). In the present study, we determine whether a short-term exposure to a known antiandrogenic pesticide, linuron (LN), suppresses spiggin mRNA in male stickleback and in androgenized female stickleback. Primers were designed from previously characterized sequences for each androgen receptor (AR) isoform in stickleback, arα and arβ, to assess whether these receptors are differentially regulated by androgen or antiandrogen exposure. Fish were exposed for 72 h to one of four treatments: control, LN (250 µg/L), 17α-methyltestosterone (MT, 500 ng/L), and an LN-MT mixture at those same concentrations. There was no effect of LN on spiggin and arβ mRNA levels in male kidney, while levels of arα were significantly increased twofold. Exposure to LN significantly inhibited MT-induced spiggin RNA production in female kidney with no effect on expression of arα and arβ. The present study is the first to demonstrate the antiandrogenic effect of LN at the transcript level and to examine androgenic/antiandrogenic responsiveness of the two ARs in the stickleback. From the present study, it was determined that measurement of spiggin RNA is a reliable and sensitive screening tool for the detection of both androgenic and antiandrogenic compounds.

Aminated cotton fibers loaded with copper(II) ions for enhanced pesticide removal performance from water in a laboratory scale batch

Diethylenetriamine cotton fibers (DET-cotton) were prepared by amination with diethylenetriamine (DET) on chlorodeoxycellulose (CDC-cotton). The evidence of grafting was confirmed by elemental and AFM analysis. Then, the modified fibers were loaded with copper (II) ions and, the abilities of both DET-cotton and [Cu(II)/DET-cotton] for binding an herbicide, i.e. Linuron (LNR) were investigated. To examine the underlying mechanism of the adsorption process, pseudo-first, pseudo-second-order, elovich and intraparticle diffusion models were fitted to experimental kinetic data. Results showed that the pseudo-second-order equation was appropriate to describe the pesticide adsorption by [Cu(II)/DET-cotton]. However, the adsorption behavior by DET-cotton followed the pseudo-first-order kinetic model. Adsorption data were further analyzed by the Langmuir, Freundlich and Jossens adsorption approaches. Attempts have also been made to recover the pesticide from exhausted adsorbent.

Weed control efficacy and selectivity of preemergence herbicides in Sorghum vulgare Perz. cultivationOcena skuteczności chwastobójczej i selektywności herbicydów stosowanych doglebowo w uprawie Sorghum vulgare Perz.

Summary In 2010–2011 field experiments were carried out to determine the weed control and phytotoxicity effect of the selected active ingredients of herbicides in Sorghum vulgare cultivation. During crop vegetation weed control was described and S. vulgare sensivity was conducted in the base of plant density, plant height and fresh mass. Following active ingredients were assessed: acetochlor, terbuthylazine + mesotrione + s-metolachlor, s-metolachlor + mesotrione, propisochlor, propisochlor + linuron, flufenacet + isoksaflutol. Data indicated that after application of: terbuthylazine + mesotrione + s-metolachlor, s-metolachlor + mesotrione and propisochlor + linuron very good weed control effect and significant plant height and fresh mass increasing were achieved.

Reaction Mechanism of Linuron Degradation in TiO2 Suspension under Visible Light Irradiation with the Assistance of H2O2

The application of TiO2/H2O/Vis (visible light) process for the aqueous degradation of linuron (LNR) has been investigated. The performance of TiO/H2O2/Vis process has been compared with other processes such as TiO2/H2O2 in the dark, TiO2/Vis, and H2O2 is in terms of LNR decay. The result showed that more than 70% LNR could be decomposed in the TiO2/H2O2/Vis. The degradation mechanism of LNR by TiO2/H2O2/Vis process has been verified through investigation of the effects of various radical scavengers on the performance of this system, monitoring the generation of photocurrent, and comparing the intermediates and decay pathways of LNR by UV-TiO2 and TiO2/ H2O2/Vis processes with 16 and 17 intermediates identified, respectively. It has been revealed that demethoxylation and demethylation through alkylic-oxidation is the major mechanism of LNR degradation while dechlorination (hydroxylation at the chlorine site) and direct hydroxylation on the benzene ring is minor in both processes. Mineralization and release of chlorine and nitrogen have been also studied.

Removal of organic pollutants from water by modified cellulose fibres

Different modified cellulose fibers were prepared and their efficiency as adsorbent for the removal of several aromatic organic compounds and three herbicides, i.e.; Alachlor (ACH), Linuron (LNR) and Atrazine (ATR), was investigated. The evolution of the adsorption capacity according to the solute structure and the modification sequence was explored. The modification was carried on under heterogeneous conditions using N,N′-carbonyldiimidazole (CDI) as an activator and different amino derivatives as grafting agent. By varying the structure of the amino derivative and the reaction sequence, different organic structures bearing diverse functional groups were generated on the surface. Evidence for the occurrence of the surface modification was confirmed by FTIR, XPS and solid-state 13C NMR spectroscopy. It was shown that the chemical modification of the fibers’ surface greatly enhanced the adsorption capacity toward organic compound dissolved in water. The adsorption capacity evolved from 20 to 50 μ mol g −1for the virgin fibers to between 400 and 1000 μ mol g −1 for the modified substrates, depending on the solute structure and the modification sequence. The efficiency of the retention property under a continuous regime was also confirmed by using a column filled with the modified fibres. Once exhausted, the column could be reused by washing its contents with ethanol, which totally extracted the trapped compounds. The regenerated column was then used in several adsorption–desorption cycles without any loss of the capacity.

Evaluation of the Antiandrogenic Effects of Flutamide, DDE, and Linuron in the Weanling Rat Assay Using Organ Weight, Histopathological, and Proteomic Approaches

The Organization for Economic Cooperation and Development (OECD) is currently funding the validation of the Hershberger assay as a rapid in vivo means of identifying (anti-) androgens. However, as the assay measures weight changes in the androgen-sensitive tissues of castrated rats, the evaluation of the androgen-stimulated intact weanling as a more ethical model to use in the assay has been requested. As part of the OECD validation exercise two weak antiandrogens, 1,1-dichloro-2,2-bis(4 chlorophenyl)ethane (DDE) and linuron (LIN), were investigated in our laboratory at several dose levels in the testosterone propionate (TP)-stimulated weanling using flutamide (FM) as a positive control. In addition to weight measurements (sex accessory tissues [SATs], epididymides, and testes), histopathological assessment of the seminal vesicles, prostate, and testes was conducted for vehicle control, TP-stimulated, and TP-stimulated animals treated with FM or the top dose level of DDE or LIN. The modulation of a novel prostate protein associated with apoptosis, L-amino acid oxidase (LAO), was evaluated in these same treatment groups. Our gravimetric data (supported by the histopathology data) indicated that the weanling assay can detect SAT and epididymal weight changes induced by the antiandrogens evaluated. Inconsistent and variable data were recorded for the testicular weight and histopathological effects, suggesting that the testis is of little value in the identification of antiandrogens using this model. Three isoforms of LAO were identified, and all were regulated by TP. Modulation of LAO by the antiandrogens indicated that this protein could be a biomarker for endocrine disruption in male rodents.

Photocatalytic Degradation of Monolinuron and Linuron in an Aqueous Suspension of Titanium Dioxide Under Simulated Solar Irradiation

The photocatalytic degradation of two phenylurea herbicides, monolinuron (MLN) and linuron (LN), was investigated in an aqueous suspension of TiO2 using simulated solar irradiation. The objective of the study was to compare their photocatalytic reactivity and to assess the influence of various parameters such as initial pesticide concentration, catalyst concentration and photonic flux on the photocatalytic degradation rate of MLN and LN. A comparative study of the photocatalytic degradation kinetics of both herbicides showed that these two compounds have a comparable reactivity with TiO2/simulated sun light. Under the operating conditions of this study, the photocatalytic degradation of MLN and LN followed pseudo first-order decay kinetics. The kobs values indicated an inverse dependence on the initial herbicide concentration and were fitted to the Langmuir-Hinshelwood equation. Photocatalytic degradation rates increased with TiO2 dosage, but overdoses did not necessarily increase the photocatalytic efficiency. The degradation rate of MLN increased with radiant flux until an optimum at 580 W m‑2 was reached and then decreased. Under these conditions, an electron-hole recombination was favored. Finally, the photocatalytic degradation rate depended on pH, where an optimum was found at a pH value close to the pH of the point of zero charge (pH = 6).