Concentrations Of Ethylenethiourea Research Articles

Efficient photocatalytic degradation of ethylenethiourea with zinc oxide photocatalysts: Parameters optimization, mechanism insight, exploration of degradation pathways and toxicity assessment

Traditional advanced oxidation processes (AOPs) for the removal of toxic and refractory ethylenethiourea (ETU) is uneconomical because of the demand for continuous chemical input and full-scale systems. Herein, ETU was efficiently mineralized without sacrificial reagents for the first time through the utilization of ZnO nano-photocatalysts which were synthesized by the adjustment of ratio between the precursor ZnCl2 and alkaline source KOH during hydrothermal process. Compared to other ZnO samples, ZnO-1/3 (1:3 molar (M) ratio of ZnCl2 to KOH) exhibited higher apparent rate constant (0.00661 min−1) towards the degradation of ETU because of more effective electron-hole separation. The optimum conditions for ETU degradation (ZnO-1/3 dosage of 0.4 g/L, initial ETU concentration of 10 mg/L and photocatalytic reaction temperature of 35 °C) were acquired according to the outcome of the response surface methodology (RSM) based on the Box-Behnken design (BBD), and the predicted maximum removal efficiency of ETU reached 93.17 % and was consistent with the experimental results under this optimum conditions. The h+ and •OH were proved to the main reactive species during the photocatalytic process by the free radical capture experiments and electron spin resonance (ESR) analysis. Furthermore, the possible degradation pathways of ETU were suggested based on the identified degradation intermediates, and the reduced toxicity of intermediates was also demonstrated through the quantitative structure–activity relationship (QSAR) prediction and the growth of mung bean seedlings. Hence, photocatalysis with ZnO can be regarded as a promising alternative for ETU elimination.

Optimization of ethylene thiourea, cyanide, and heavy metals removal and gas production enhancement in organosulfur pesticide wastewater using ferromagnetic biochar in anaerobic membrane bioreactor

Anaerobic membrane bioreactor (AnMBR) and biochar technologies have rarely been used in pesticide wastewater treatment, their performance and feasibility need further confirmation. This study compared a novel AnMBR (R2) with ferromagnetic biochar derived from traditional Chinese medicine residues to a conventional AnMBR (R1) without ferromagnetic biochar, focusing on degradation of organosulfur pesticide wastewater characterized by high toxicity and COD content and observing biogas production under various temperatures and hydraulic retention times (HRTs). The relationship between wastewater toxicity (COD, ethylene thiourea (ETU), cyanide, total manganese (TMn) and total zinc (TZn)) and biogas production was also explored. The optimal parameters were determined, with R1 and R2 having the same effect. Compared to R1, ETU removal in R2 increased from 40.7 % to 61.0 % (10 °C), from 64.6 % to 71.6 % (15 °C), from 76.9 % to 87.0 % (25 °C), and from 86.4 % to 92.4 % (35 °C). Similarly, the HRT was 48 h at 15 °C in R2 and at 25 °C in R1, both achieving a comparable COD removal of approximately 75.2 %. Cyanide removal in R2 was 2.4–9.6 % higher than in R1 across various temperatures. In addition, compared to R1, effluent concentrations of TMn in R2 were reduced by 378.8 ± 96.2 mg/L at 25 °C with the HRT of 18 h. The TZn average enhancements removal in R2 were higher than those in R1 by 6.6 % (10 °C), 10.0 % (15 °C), 3.8 % (25 °C), and 4.1 % (35 °C). Importantly, biogas production in R2 increased by 5.3–15.9 % at 25 °C. There was a significant negative correlation between biogas production and the concentrations of ETU and cyanide. This highlighted the dual benefit of R2 in enhancing pollutant degradation and biogas energy recovery, providing basic data for energy-efficient and low-carbon operations in pesticide wastewater treatment.

Assessment of Mancozeb Exposure, Absorbed Dose, and Oxidative Damage in Greenhouse Farmers.

Mancozeb (MNZ) is a fungicide commonly employed in many countries worldwide. This study assesses MNZ absorption dynamics in 19 greenhouse farmers, specifically following dermal exposure, aiming to verify the efficacy of both preventive actions and protective equipment. For data collection, a multi-assessment approach was used, which included a survey to record study population features. MNZ exposure was assessed through the indirect measurement of ethylene thiourea (ETU), widely employed as an MNZ biomarker. The ETU concentration was measured with the patch method, detecting environmental ETU trapped in filter paper pads, applied both on skin and working clothes, during the 8 h work shift. Urine and serum end-of-shift samples were also collected to measure ETU concentrations and well-known oxidative stress biomarkers, respectively, namely reactive oxygen metabolites (ROMs), advanced oxidation protein products (AOPPs), and biological antioxidant potential (BAP). It was observed that levels of ETU absorbed and ETU excreted were positively correlated. Additionally, working clothes effectively protected workers from MNZ exposure. Moreover, following stratification of the samples based on the specific working duty (i.e., preparation and spreading of MNZ and manipulation of MNZ-treated seedlings), it was found that the spreading group had higher ETU-related risk, despite lower chronic exposure levels. AOPP and ROM serum levels were higher in MNZ-exposed subjects compared with non-exposed controls, whereas BAP levels were significantly lower. Such results support an increase in the oxidative stress upon 8 h MNZ exposure at work. In particular, AOPP levels demonstrated a potential predictive role, as suggested by the contingency analysis results. Overall, this study, although conducted in a small group, confirms that ETU detection in pads, as well as in urine, might enable assessment of the risk associated with MNZ exposure in greenhouse workers. Additionally, the measurement of circulating oxidative stress biomarkers might help to stratify exposed workers based on their sensitivity to MNZ. Pivotally, the combination of both ETU measurement and biological monitoring might represent a novel valuable combined approach for risk assessment in farmhouse workers exposed to pesticides. In the future, these observations will help to implement effective preventive strategies in the workplace for workers at higher risk, including greenhouse farmers who are exposed to pesticides daily, as well as to clarify the occupational exposure levels to ETU.

Modeling the distribution of an adsorbing solute in a catalyzed column

• Ethylene Thiourea (ETu) is a model catalytic reagent used to leach copper from chalcopyrite . • ETu interacts with the bed of ore as shown by comparison to Cu and Li which are inert. • A 2-D axisymmetric model of an adsorbing, reacting solute is used to explain ETu curves. • The Redlich Peterson adsorption isotherm explains the ETu curves generated. • The 2-D model is validated for different concentrations of ETu, flow rates and heights of column. Catalytic solutes have been reported to significantly enhance dissolution rates of copper from chalcopyrite. Ethylene thiourea (ETu), a thiocarbonyl compound which has been shown to have such a catalytic effect, is used as a model solute to study the distribution of solute in a column of crushed ore under a point source to simulate the effects of a single drip emitter. Steady state infiltration tests of ETu solution are performed to generate ETu breakthrough curves which are compared with curves from metal ions such as copper and lithium to estimate solute transport properties such as adsorption and reaction. The Redlich-Peterson isotherm is used successfully to describe the adsorption behavior of ETu in a column of crushed ore. A 2D axisymmetric model of solute transport is used to estimate adsorption and reaction rate constants by analyzing the sensitivity of model break through curves and comparing them to experimental results. Further, the model populated with the computed parameters is used to estimate ETu breakthrough curves resulting from varying input concentrations, column heights and infiltration rates.

Urinary metabolites of non-persistent pesticides and serum hormones in Spanish adolescent males

ObjectiveTo assess the relationship of urinary concentrations of ethylenethiourea (ETU), the main degradation product of ethylene bis-dithiocarbamate fungicides, 3-phenoxybenzoic acid (3-PBA), a common metabolite of many pyrethroids, and 1-naphthol (1N), a metabolite of the carbamate insecticide carbaryl, with hormone concentrations in adolescent males; and to examine interactions between pesticide metabolites and polymorphisms in xenobiotic metabolizing enzymes, including CYP2C19 and CYP2D6, in relation to hormone concentrations. MethodsA cross-sectional study was conducted in 134 males from the Spanish Environment and Childhood (INMA)-Granada cohort. Urine and serum samples were collected from participants during the same clinical visit at the age of 15–17 years. First morning urine void was analyzed for concentrations of ETU, 3-PBA, and 1N. Serum was analyzed for concentrations of reproductive hormones (testosterone, 17β-estradiol [E2], dehydroepiandrosterone sulfate [DHEAS], sex hormone binding globulin [SHBG], luteinizing hormone [LH], follicle stimulating hormone [FSH], anti-Müllerian hormone [AMH], and prolactin), thyroid hormones (free thyroxine [FT4], total triiodothyronine [TT3], and thyroid stimulating hormone [TSH]), insulin growth factor 1 (IGF-1), adrenocorticotropic hormone (ACTH), and cortisol. CYP2C19 G681A and CYP2D6 G1846A polymorphisms were determined in blood from 117 participants. Multiple linear regression, interaction terms, and stratified analyses were performed. ResultsUrinary ETU was detected in 74.6% of participants, 1N in 38.1%, and 3-PBA in 19.4%. Positive associations between detectable 3-PBA and TT3 and between detectable 1N and DHEAS were found, and marginally-significant associations of 1N with reduced E2 and FSH were observed. Poor CYP2C19 and CYP2D6 metabolizers (GA and AA genotype carriers) showed a greater increase in DHEAS for detected versus undetected 1N compared with GG genotype carriers. Poor CYP2D6 metabolizers (1846 GA and AA genotypes) evidenced increased cortisol for detected versus undetected ETU. ConclusionsThe associations observed between urinary pesticide metabolites and altered thyroid and reproductive hormones are novel and should be verified in studies with larger sample size. Further research on gene-environment interactions is warranted to establish individual susceptibility to pesticides and the risk of adverse health effects.

Substrate evaluation for biobeds in the degradation of ethylene bis-dithiocarbamate in wastewater from pesticide application in banana.

The efficacy of biobeds was evaluated by testing three agricultural residues (sugarcane top, banana stem, and eucalyptus chip) as substrates for the degradation of ethylene bis-dithiocarbamate (EBDC) and ethylene thiourea (ETU) in wastewater from banana spraying. Acrylic columns with a capacity to treat 1L/ea. of wastewater were used as experimental units. Each unit was filled with different proportions of the test substrate (30%, 50% and 70% v/v) and the difference in volume was made up of equal parts of sugar cane cachasse and Fluvisol soil. Subsequently, the units were contaminated with suspensions of 878mgL-1 of EBDC, and the dose was repeated periodically. The ETU concentration and leachate toxicity were evaluated every month for six months. The mixtures with 30% sugarcane top and 50% eucalyptus chip gave the best results, with leachable ETU concentrations down to a level protective of the environment, and toxicity down to background levels or nearly so. This was only found in mixtures with a high C:N ratio (20-25), thus, the effectiveness of the biobeds appears to be related to high lignolytic activity. .

The fungicide Mancozeb reduces spheroid attachment onto endometrial epithelial cells through downregulation of estrogen receptor β and integrin β3 in Ishikawa cells

Mancozeb is a metal-containing ethylene bis-dithiocarbamate fungicide widely used in agriculture. Ethylene thiourea (ETU) is the primary metabolite of Mancozeb. Mancozeb has been associated with spontaneous abortions and abnormal menstruation in women. However, the effects of Mancozeb and ETU on embryo attachment remain unknown. The human blastocyst surrogate trophoblastic spheroids (JEG-3), endometrial epithelial surrogate adenocarcinoma cells (Ishikawa), or human primary endometrial epithelial cells (EECs) monolayer were used in the spheroid attachment models. Ishikawa and EECs were pretreated with different concentrations of Mancozeb or ETU for 48 h before the attachment assay. Gene expression profiles of Ishikawa cells were examined to understand how Mancozeb modulates endometrial receptivity with Microarray. The genes altered by Mancozeb were confirmed by qPCR and compared with the ETU treated groups. Mancozeb and ETU treatment inhibited cell viability at 10 μg/mL and 5000 µg/mL, respectively. At non-cytotoxic concentrations, Mancozeb at 3 μg/mL and ETU at 300 μg/mL reduced JEG-3 spheroid attachment onto Ishikawa cells. A similar result was observed with human primary endometrial epithelial cells. Mancozeb at 3 μg/mL modified the transcription of 158 genes by at least 1.5-fold in Microarray analysis. The expression of 10 differentially expressed genes were confirmed by qPCR. Furthermore, Mancozeb decreased spheroid attachment possibly through downregulating the expression of endometrial estrogen receptor β and integrin β3, but not mucin 1. These results were confirmed in both overexpression and knockdown experiments and co-culture assay. Mancozeb but not its metabolite ETU reduced spheroid attachment through modulating gene expression profile and decreasing estrogen receptor β and integrin β3 expression of endometrial epithelial cells.

N-nitrosoethylenethiourea formation at environmentally-relevant concentrations of ethylenethiourea in a pooled groundwater sample

N-nitroso compounds form from the interaction between nitrosatable precursors and nitrite under acidic conditions. A majority of N-nitroso compounds tested show evidence of carcinogenicity in animal models. Formation of N-nitroso compounds may occur from exposure to precursors in drinking water, but the extent of formation depends on a number of factors, including concentration of substrates, presence of catalysts and inhibitors, and pH. The objective of this study was to examine these factors in pesticide-associated N-nitroso (PANN) compound formation in drinking water. In preliminary screening experiments, nine nitrosatable pesticides and degradation products were individually reacted at environmentally-relevant concentrations (≤ 20 μg L‐−1) with sodium nitrite (NaNO2) and hydrochloric acid (HCl) in ultra-pure water. Only ethylenethiourea (ETU) showed evidence of PANN compound formation in initial experiments and was further tested for N-nitrosoethylenethiourea (N-ETU) formation in a pooled groundwater sample (comprised of five tap water samples combined into one homogenous sample) collected from an agricultural region of Prince Edward Island in Canada, where nitrate contamination is a known concern. Evidence of N-ETU formation in the groundwater sample was observed within 30 min at concentrations 7.5, 10, and 20 μg L−1. Analysis of target compounds and semi-target PANN compounds was performed using ultra-high pressure liquid chromatography coupled with high resolution orbital ion trap mass spectrometry. These preliminary experiments serve to inform about potential PANN compound formation in groundwater. The results of this study suggest that ETU is capable of forming potentially carcinogenic N-ETU in water containing nitrite/nitrate at trace concentrations under acidic conditions. Thus, these findings suggest that N-ETU formation may be a concern for individuals exposed to low concentrations of ETU in groundwater.

Development and validation of a novel enzyme-linked immunosorbent assay for monitoring ethylene thiourea in soil and vegetable samples

A novel enzyme-linked immunosorbent assay (ELISA) was developed for the detection of ethylene thiourea (ETU); a metabolite of ethylenebisdithiocarbamates (EBDCs) fungicides such as mancozeb. The ELISA performed well under optimal conditions based one limit of detection (0.201 ng mL−1), sensitivity (IC50 3.71 µg mL−1), recovery (81.6–102.7%) and relative standard deviation (<12.5%). This method was used to determine ETU residues in soil and vegetables after 0, 1, 3, 5, 7 and 10 days following mancozeb application. Concentrations of ETU gradually increased in the soil up to the tenth day of application. While in tomato and potato samples, the maximum concentrations of ETU residues were reached on the third and fifth days, respectively, and then dissipated with half-lives of 1.33 and 4.33 days, respectively. The method was simple, rapid, cost-effective, environmentally friendly, and has the potential for high sample throughput.

Exposure to fungicides and attention in 6-year old children from the Infants′ Environmental Health Study (ISA)

TPS 731: Neurological effects in children, Exhibition Hall, Ground floor, August 26, 2019, 3:00 PM - 4:30 PM Background: Several fungicides are suspected endocrine disruptors and may impair children’s neurodevelopment, but data from prospective studies are lacking. In Costa Rica, fungicides are aerially sprayed and used postharvest on bananas. We examined whether exposure to fungicides was associated with poor attention in children from the Infants Environmental Health Study (ISA). Methods: To evaluate attention, we applied the Conners Continuous Performance Test (K-CPT-II) in 6-year old children (mean 6.4 ± 0.4 years) (n=268) using T-scores of omissions, commissions and Hit Reaction Time (HRT). To assess exposure to the fungicides mancozeb, pyrimethanil, and thiabendazole, we measured ethylenethiourea (ETU), hydroxy pyrimethanil (OHP), and 5-hydroxythiabendazole (5-OHT), respectively, in repeated urine samples collected during pregnancy and 5-6 years of age. We ran separate linear regression models for log-10 transformed mean prenatal, and mean child metabolite concentrations and CPT-II, adjusting for child age, child sex, HOME score, and maternal education. We examined effect-modification by sex. Results: Median (p25-p75) prenatal specific gravity-adjusted ETU, OHP and 5-OHT were 3.40 (2.38-4.79), 0.50 (0.21-1.28) and 0.10 (0.03-0.53) µg/L, and current ETU, OHP and 5-OHT were 2.66 (1.90-3.63), 0.86 (0.34-2.32) and 0.12 (0.04-0.49) µg/L, respectively. Higher current ETU concentrations were associated with increased omissions (ß=8.4 95%CI 3.5-13.4, per ten-fold increase in exposure). The association was stronger for girls (ß=7.3, 95%CI 0.6-13.9) as compared to boys (ß=5.5, 95%CI -1.6-12.6). For girls, both higher prenatal and current OHP concentrations were associated with increased omissions (ß=3.1, 95%CI 0.6-5.6 and ß=4.0, 95%CI 0.9-7.0, respectively), and current OHP concentrations were also associated with slower responses (ß=2.1, 95%CI 0.2.-2.9). OHT and prenatal ETU were not associated with measures of attention. Conclusion: Six-year old children with higher current exposure to mancozeb and higher prenatal and current exposure to pyrimethanil had poorer attention as compared to children with lower exposures, the effect was stronger for girls.

Electrochemical Characterization of Mancozeb Degradation for Wastewater Treatment Using a Sensor Based on Poly (3,4-ethylenedioxythiophene) (PEDOT) Modified with Carbon Nanotubes and Gold Nanoparticles.

Mancozeb is a worldwide fungicide used on a large scale in agriculture. The active component and its main metabolite, ethylene thiourea, has been related to health issues. Robust, fast, and reliable methodologies to quantify its presence in water are of great importance for environmental and health reasons. The electrochemical evaluation of mancozeb using a low-cost electrochemical electrode modified with poly (3,4-ethylene dioxythiophene), multi-walled carbon nanotubes, and gold nanoparticles is a novel strategy to provide an in-situ response for water pollution from agriculture. Additionally, the thermal-, electrochemical-, and photo-degradation of mancozeb and the production of ethylene thiourea under controlled conditions were evaluated in this research. The mancozeb solutions were characterized by electrochemical oxidation and ultraviolet-visible spectrophotometry, and the ethylene thiourea concentration was measured using ultra-high-performance liquid chromatography high-resolution mass spectrometry. The degradation study of mancozeb may provide routes for treatment in wastewater treatment plants. Therefore, a low-cost electrochemical electrode was fabricated to detect mancozeb in water with a robust electrochemical response in the linear range as well as a quick response at a reduced volume. Hence, our novel modified electrode provides a potential technique to be used in environmental monitoring for pesticide detection.

Prenatal Mancozeb Exposure, Excess Manganese, and Neurodevelopment at 1 Year of Age in the Infants' Environmental Health (ISA) Study.

Background:Although growing evidence suggests that early-life excess manganese (Mn) impairs neurodevelopment, data on the neurodevelopmental effects of mancozeb, a fungicide containing Mn, and its main metabolite ethylenethiourea (ETU) are limited.Objective:We examined whether prenatal mancozeb exposure and excess Mn were associated with neurodevelopment in 355 1-y-old infants living near banana plantations with frequent aerial mancozeb spraying in Costa Rica.Methods:We measured urinary ETU, hair Mn, and blood Mn concentrations in samples collected 1–3 times during pregnancy from mothers enrolled in the Infants’ Environmental Health (ISA) study. We then assessed neurodevelopment in their 1-y-old infants using the Bayley Scales of Infant and Toddler Development, 3rd edition (BSID-III). We estimated exposure–outcome associations using linear regression models adjusted for maternal education, parity, gestational age at birth, child age, Home Observation for Measurement of the Environment score, and location of neurodevelopmental assessment.Results:Median (P25–P75) urinary ETU, hair Mn, and blood Mn measured during pregnancy were (2.4–4.9; specific gravity–corrected), (0.9–4.1), and (20.3–28.0), respectively. Among girls, higher ETU was associated with lower social-emotional scores [ (95% CI: , 0.4)], whereas higher hair Mn was associated with lower cognitive scores [ (, 0.1)]. Among boys, higher hair Mn was associated with lower social-emotional scores [ (, )]. We observed null associations for blood Mn, language, and motor outcomes.Conclusions:Our findings indicate that maternal exposure to mancozeb and excess Mn during pregnancy may have adverse and sex-specific effects on infant neurodevelopment. https://doi.org/10.1289/EHP1955

Phytoremediation of groundwater contaminated with pesticides using short-rotation willow crops: A case study of an apple orchard

ABSTRACTThe occurrence of pesticides in groundwater represents an important health issue, notably for population whose drinking water supply source is located in agricultural areas. However, few solutions have been considered with regard to this issue. We tested the efficacy of a vegetal filtering system made of shrub willows planted at a high density (16,000 plants ha−1) to filter or degrade pesticides found in the groundwater flowing out of an apple orchard. Ethylene urea (EU), ethylene thiourea (ETU), tetrahydrophthalimide (THPI), atrazine, and desethylatrazine were monitored in the soil solution in willow and control plots over one growing season. ETU and atrazine concentrations were lower in the willow plots relative to the control plots, whereas desethylatrazine concentration was higher in the willow plots. No significant difference was detected for EU and THPI. Furthermore, pesticide concentrations displayed complex temporal patterns. These results suggest that willow filter systems can filter or degrade pesticides, notably ETU and atrazine, and could be used for phytoremediation purposes. Yet, this potential remains to be quantified with further studies using experimental settings allowing more estimation in time and space.

Manganese concentrations in drinking water from villages near banana plantations with aerial mancozeb spraying in Costa Rica: Results from the Infants' Environmental Health Study (ISA)

Elevated manganese (Mn) in drinking water has been reported worldwide. While, naturally occurring Mn in groundwater is generally the major source, anthropogenic contamination by Mn-containing fungicides such as mancozeb may also occur. The main objective of this study was to examine factors associated with Mn and ethylenethiourea (ETU), a degradation product of mancozeb, in drinking water samples from villages situated near banana plantations with aerial spraying of mancozeb. Drinking water samples (n = 126) were obtained from 124 homes of women participating in the Infants' Environmental Health Study (ISA, for its acronym in Spanish), living nearby large-scale banana plantations. Concentrations of Mn, iron (Fe), arsenic (As), lead (Pb), cadmium (Cd) and ethylenethiourea (ETU), a degradation product of mancozeb, were measured in water samples. Only six percent of samples had detectable ETU concentrations (limit of detection (LOD) = 0.15 μg/L), whereas 94% of the samples had detectable Mn (LOD = 0.05 μg/L). Mn concentrations were higher than 100 and 500 μg/L in 22% and 7% of the samples, respectively. Mn was highest in samples from private and banana farm wells. Distance from a banana plantation was inversely associated with Mn concentrations, with a 61.5% decrease (95% CI: −97.0, −26.0) in Mn concentrations for each km increase in distance. Mn concentrations in water transported with trucks from one village to another were almost 1000 times higher than Mn in water obtained from taps in houses supplied by the same well but not transported, indicating environmental Mn contamination. Elevated Mn in drinking water may be partly explained by aerial spraying of mancozeb; however, naturally occurring Mn in groundwater, and intensive agriculture may also contribute. Drinking water risk assessment for mancozeb should consider Mn as a health hazard. The findings of this study evidence the need for health-based World Health Organization (WHO) guidelines on Mn in drinking water.

Ozonation and peroxone oxidation of ethylenethiourea in water: operational parameter optimization and by-product identification.

The objective of this work was to study the degradation and mineralization of ethylenethiourea (ETU) in water by ozonation at different pH values and in the presence of hydrogen peroxide. Degradation experiments were performed using an initial ETU concentration of 50 ppm for 180 min with a gas flux of 0.25 dm(3) min(-1) and an O3 production rate of 12.1 mg min(-1). Degradation of by-products was monitored by direct injection electrospray ionization mass spectrometry (ESI-MS), ETU concentration was determined by HPLC-UV, and its mineralization was detected by total organic carbon (TOC) analysis. Optimum degradation of ETU in water was observed at pH = 11, whereas at pH = 3, the degradation of ETU was slowest, indicating that the reaction occurred through different mechanisms. The additional effects of hydroxyl radicals formed at the highest pH can be used to explain the results obtained in this study. Peroxone experiments were carried out in the presence of 400 and 800 mg L(-1) H2O2; the degradation of ETU was faster at 400 mg L(-1) H2O2. This was attributed to the scavenging effect of the excess H2O2. ETU treatment by ozonation produced several by-products of degradation such as ethylene urea and 2-imidazoline.

Aerial application of mancozeb and urinary ethylene thiourea (ETU) concentrations among pregnant women in Costa Rica: the Infants' Environmental Health Study (ISA).

Background: Mancozeb and its main metabolite ethylene thiourea (ETU) may alter thyroid function; thyroid hormones are essential for fetal brain development. In Costa Rica, mancozeb is aerially sprayed at large-scale banana plantations on a weekly basis.Objectives: Our goals were to evaluate urinary ETU concentrations in pregnant women living near large-scale banana plantations, compare their estimated daily intake (EDI) with established reference doses (RfDs), and identify factors that predict their urinary ETU concentrations.Methods: We enrolled 451 pregnant women from Matina County, Costa Rica, which has large-scale banana production. We visited 445 women up to three times during pregnancy to obtain urine samples (n = 872) and information on factors that possibly influence exposure. We determined urinary ETU concentrations using liquid chromatography mass spectrometry.Results: Pregnant women’s median urinary ETU concentrations were more than five times higher than those reported for other general populations. Seventy-two percent of the women had EDIs above the RfD. Women who lived closest (1st quartile, < 48 m) to banana plantations on average had a 45% (95% CI: 23, 72%) higher urinary ETU compared with women who lived farthest away (4th quartile, ≥ 565 m). Compared with the other women, ETU was also higher in women who washed agricultural work clothes on the day before sampling (11%; 95% CI: 4.9, 17%), women who worked in agriculture during pregnancy (19%; 95% CI: 9.3, 29%), and immigrant women (6.2%; 95% CI: 1.0, 13%).Conclusions: The pregnant women’s urinary ETU concentrations are of concern, and the principal source of exposure is likely to be aerial spraying of mancozeb. The factors predicting ETU provide insight into possibilities for exposure reduction.Citation: van Wendel de Joode B, Mora AM, Córdoba L, Cano JC, Quesada R, Faniband M, Wesseling C, Ruepert C, Öberg M, Eskenazi B, Mergler D, Lindh CH. 2014. Aerial application of mancozeb and urinary ethylene thiourea (ETU) concentrations among pregnant women in Costa Rica: The Infants’ Environmental Health Study (ISA). Environ Health Perspect 122:1321–1328; http://dx.doi.org/10.1289/ehp.1307679

Methylene blue sensitized oxidation of ethylene thiourea in cationic micellar medium

Ethylene thiourea (ETU) is relatively stable to hydrolysis but can be rapidly photolysed in the presence of photosensitizers. An aqueous solution of 8.0×10−4M ETU and 5.0×10−5M methylene blue (MB) was photolysed for 90min with halogen lamp both in the presence and absence of cetyltrimethyl ammonium bromide (CTAB). 2-Imidazoline-2-yl-sulphinic acid (ISH) has been identified as the primary product both in the homogeneous and micellar media by chromatographic spectral analysis. The effects of various kinetic parameters were studied to lay down the mechanistic details of the reaction. On the basis of the kinetic studies the participation of singlet oxygen at low ETU concentration is postulated. However, ionic mechanism is suggested at high ETU concentration.

Reference values for ethylenethiourea in urine in Northern Italy: Results of a pilot study

This study was carried out to define reference values for urinary ethylenethiourea (ETU) in the Northern Italy population and to identify the sources of exposure. Ninety-five healthy subjects were selected. A spot urine sample was collected in the morning, and analyzed using GC/MS in the EI/SIM mode. Thirty-nine subjects showed urinary ETU concentrations lower than the limit of detection (LOD, 0.4 μg/g creatinine), and the remainders ETU concentrations ranging from 0.5 to 11.6 μg/g creatinine. No correlation was shown between smoke or alcohol intake and urinary ETU concentrations. Based on data on ethylene-bis-dithiocarbamate (EBDC) concentrations in food, we estimated a total EBDCs intake of 31.7–50.1 μg/day. These values are largely below the ADIs, but explain the presence of small amounts of ETU in the urine samples we have analyzed. Finally, it was estimated that the mean ETU in urine in the Italian general population is 0.6–0.8 μg/g creatinine, with a 95th percentile of 4.5–5.0 μg/g creatinine. These values can be used as reference, to compare the results of biological monitoring activities carried out on EBDCs occupationally and environmentally exposed populations.

Description and initial evaluation of a Xenopus metamorphosis assay for detection of thyroid system‐disrupting activities of environmental compounds

A need is recognized for the development and evaluation of bioassays for detection of thyroid system-disrupting compounds. The issue of testing for thyroid disruption can be addressed by exploiting amphibian metamorphosis as a biological model. In the present study, a test protocol for a Xenopus metamorphosis assay (XEMA) was developed and its interlaboratory transferability was evaluated in an informal ring test with six laboratories participating. In the XEMA test, exposure of Xenopus laevis tadpoles was initiated at stages 48 to 50 and continued for 28 d. Development and growth of tadpoles were assessed by means of developmental stage and whole body length determinations, respectively. For initial test protocol evaluation, thyroxine (T4), and propylthiouracil (PTU) were used as positive controls for thyroid system-modulating activity, and ethylenethiourea (ETU) was used as a test compound. Exposure of tadpoles to 1 microg/L T4 produced a significant acceleration of metamorphosis whereas PTU concentrations of 75 and 100 mg/L completely inhibited metamorphosis. Five different ETU concentrations (5, 10, 25, 50, and 100 mg/L) were tested and a concentration-dependent inhibition of metamorphosis was observed. None of the compounds affected tadpole survival, and only PTU caused a slight retardation in tadpole growth. This study demonstrates that the XEMA test provides a sensitive, robust, and practical testing approach for detection of compounds with both agonistic and antagonistic effects on the thyroid system in Xenopus tadpoles.

Determination of degradation products and pathways of mancozeb and ethylenethiourea (ETU) in solutions due to ozone and chlorine dioxide treatments.

The objective of the present study was to determine the degradation products of mancozeb and ethylenethiourea (ETU) and elucidate the possible degradation pathways in solution as a result of chemical oxidation using ozone and chlorine dioxide. This study was developed in a solution at 100 ppm of mancozeb and ETU concentration over the course of 60 min. Two different oxidizing agents used in this study were (1) ozone at 3 ppm and (2) chlorine dioxide at 20 ppm. Ozone was continuously provided throughout the course of the reaction. Degradation products were detected with high-resolution GC-MS. The total analysis time was 4 min per sample combined with rapid GC separation and time-of-flight mass spectrometry (TOFMS). Hydrolysis of mancozeb led to m/z 144 ion fragmentation, which is 5-imidazoledithiocarboxylic acid, as a major degradation product. ETU showed M(+) 102, which corresponds to its mass, indicating this compound was stable in distilled water and did not undergo hydrolysis during 60 min. The average retention times of mancozeb and ETU were approximately 181-189 and 210-230 s, respectively. Ozonation of mancozeb produced ETU as a major product. Treatment of ETU with ozone produced several degradation compounds. From prolonged ozonation, the CS(2) or CS group was removed. Overall, several byproducts identified were M(+) 60, M(+) 84, M(+) 163, M(+) 117, and M(+) 267 by ozone and M(+) 117, M(+) 86, and M(+) 163 by chlorine dioxide treatment. Several of these have been reported, but others have never been reported previously.