•Multiple spectroscopic analyses were applied to investigate agrochemicals transformation in environment.•Three novel compounds were isolated and identified as triafamone metabolites.•The fate and transformation pathway of triafamone in rice paddy were revealed.•Long-term consumption of the triafamone-containing brown rice is relatively safe.•Elucidation of environmental impacts by exposure to these triazine or oxazolidinedione metabolites is warranted.Triafamone, a sulfamide herbicide, has been extensively utilized for weed control in rice paddies in Asia. However, its fate and transformation in the environment have not been established. Through a rice paddy microcosm-based simulation trial combined with multiple spectroscopic analyses, we isolated and identified three novel metabolites of triafamone, including hydroxyl triafamone (HTA), hydroxyl triafamone glycoside (HTAG), and oxazolidinedione triafamone (OTA). When triafamone was applied to rice paddies at a concentration of 34.2 g active ingredient/ha, this was predominantly distributed in the paddy soil and water, and then rapidly dissipated in accordance with the first-order rate model, with half-lives of 4.3–11.0 days. As the main transformation pathway, triafamone was assimilated by the rice plants and was detoxified into HTAG, whereas the rest was reduced into HTA with subsequent formation of OTA. At the senescence stage, brown rice had incurred triafamone at a concentration of 0.0016 mg/kg, but the hazard quotient was <1, suggesting that long-term consumption of the triafamone-containing brown rice is relatively safe. The findings of the present study indicate that triafamone is actively metabolized in the agricultural environment, and elucidation of the link between environmental exposure to these triazine or oxazolidinedione moieties that contain metabolites and their potential impacts is warranted.Download high-res image (347KB)Download full-size image

•We reported firstly that acetochlor induced cardiovascular toxicity in zebrafish.•Acetochlor-induced cardiovascular toxicity was characterized by bradycardia, pericardial edema, circulation defect and thrombosis.•The thrombosis induced by acetochlor may be triggered by circulation defects resulted from bradycardia.•Down-regulation of Nkx2.5 and Gata4 might be the possible molecular basis of cardiovascular toxicity of acetochlor.•The data generated here can provide valuable information on humans cardiovascular disease risk of acetochlor.The risk of acetochlor to human health is still unclear, prompting concern over its risk, especially to pesticide suicides population, occupational population (farmers, retailers and pharmaceutical workers), and special population (young children and infants, pregnant women, older people, and those with compromised immune systems). This study was to explore the toxic effect and the possible mechanism of toxic action of acetochlor using zebrafish larvae whose toxicity profiles have been confirmed to be strikingly similar with mammalian. The result indicated that the toxic target organ of acetochlor was cardiovascular system. Thus, cardiovascular toxicity evaluation was investigated systematically. The main phenotypes of cardiovascular toxicity induced by acetochlor were bradycardia, pericardial edema, circulation defect, and thrombosis; Malformed heart was confirmed by histopathological examination. Thrombosis which maybe triggered by bradycardia was further studied using o-dianisidine for erythrocyte staining; Substantial thrombus in the caudal vein and significantly reduced heart red blood cells (RBCs) intensity which can reflect the thrombosis degree were observed in zebrafish in a concentration-dependent manner. Additionally, the mRNA expression level of Nkx2.5 and Gata4 related to induction of cardiac program were down-regulated significantly by quantitative real-time polymerase chain reaction (qRT-PCR), which could cause defects in the cardiovascular system. For the first time, our results demonstrated that acetochlor induced cardiovascular toxicity, and down-regulation of Nkx2.5 and Gata4 might be its possible molecular basis. Our data generated here might provide novel insights into cardiovascular disease risk following acetochlor exposure to human, especially to pesticide suicides population, occupational population and special population.

Endocrine-disrupting chemicals (EDCs) in the environment have adverse effects on humans and wildlife. A method based on ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) for the determination of 26 EDCs (including five estrogens, eight androgens, three progestogens, six glucocorticoids, two mineralocorticoids and two thyroid hormones) in fish and water was developed. Various experimental parameters that could affect the extraction efficiencies were investigated in detail. The sample was extracted by a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method with 20 mL of acetonitrile (for fish) or 5 mL of ethyl acetate (for water), and then cleaned-up using an Oasis HLB SPE (solid-phase extraction) cartridge. The analytes were quantified using an isotope-labelled internal standard and recoveries between 69.1% and 120.5% were obtained. The relative standard deviation of inter- and intra-day analyses for all the compounds was below 20%. The detection limits ranged from 0.01 to 0.98 ng mL−1 for water and 0.01 to 9.04 ng g−1 for fish. For real samples, progesterone and trenbolone were detected in zebrafish (Danio rerio) samples at 5.73 ± 0.21 and 7.45 ± 0.34 ng g−1, respectively. There was no target analyte detected in tap-water samples. The developed method would be useful for monitoring EDC abuse in fishery, potential EDC screening and risk assessment in aquatic toxicology.

Ultrahigh-performance liquid chromatography coupled to electrospray positive ionization and tandem mass spectrometry (UHPLC-ESI(+)-MS/MS) was applied for the quantification and identification of azocyclotin and cyhexatin in fruit samples. Homogenized samples were extracted with acetonitrile, without derivatization, and then a cleanup step using Florisil SPE cartridge was applied. Under the optimized conditions, recovery studies were carried out on spiked matrices (4 fruits including orange, apple, peach and grape) with azocyclotin and cyhexatin at spiking levels of 2–200 μg kg−1. The mean recoveries were 71–105%, with relative standard deviations in the range of 2–13%. The quantification of analytes was carried out using the most sensitive transition for every compound and by “matrix-matched” standards calibration. The method limits of detection (S/N 3:1) achieved are in the range of 0.1–0.3 μg kg−1. The intra-day precision (n = 5) for analytes in fruit samples spiked at an intermediate level (20 μg kg−1) was between 6% and 10%, and the inter-day precision (n = 10) was between 8% and 13%.

•This was the first report on analysis of amicarthiazol residues by UPLC-MS/MS.•The method has been successfully developed and validated with the good sensitivity and selectivity, and met the current requirements for the analysis of pesticide residue.•The method be a helpful tool for the controlling and monitoring of the risks posed by amicarthiazol to human health and environment safety.A reliable and rapid method has been optimized to determine the residue of amicarthiazol in soil and environmental water samples. After extraction and evaporation, the extraction was carried out with solid phase extraction (SPE) cleanup using HLB cartridge (only soil samples) and for the quantitative determination by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The resulting residues of amicarthiazol were analyzed by a gradient separation performed on a UPLC system with a C18 column, methanol and water containing 0.1% (v v−1) formic acid as the mobile phase in the mode of electrospray positive ionization (ESI+) and multiple reaction monitoring (MRM). Results showed that the recoveries for spiked samples were 74.4–97.1% and 72.1–109.9% for soil and water, respectively, with the relative standard deviation (RSD) less than 10.2% when fortified at 10, 100 and 1000 μg L−1. The limits of detection (LODs) and the limits of quantification (LOQs) for matrix matched standards ranged from 0.073–0.425 μg L−1 and 0.243–1.42 μg L−1. The intra-day precision (n = 5) and the inter-day precision over 10 days (n = 10) for the amicarthiazol in soils and water samples spiked at 100 μg L−1 was 7.9% and 15.9%, respectively. Results indicated that the developed method could be a helpful tool for the controlling and monitoring of the risks posed by amicarthiazol to human health and environment safety.

Milbemycins have received considerable interest in agricultural chemistry due to a special action mode, extremely high activity against arachnoide pests, low toxicity to mammals, and environmentally benign characteristics. Two series of novel milbemycin analogues (4Ia−6IIc) containing alkyl and aryl groups at the 4′- and 13-positions were designed and synthesized by five schemes. These analogues were identified by 1H NMR, 13C NMR, and elemental analysis (or HRMS). Their insecticidal activities against carmine spider mite, oriental armyworm, and black bean aphid were evaluated. The results showed that all of the title compounds had low acaricidal activity against carmine spider mite. However, most of them exhibited good insecticidal activities against oriental armyworm and black bean aphid at a concentration of 200 mg L−1. The most potent substituents of 2,2-dimethylbutanoyl (4Ib), phenylacetyl (4IIm), and (Z)-1-(methoxyimino)-1-phenylacetyl (4IIn) exhibited the highest larvicidal activities, and its insecticidal LC50 values against oriental armyworm were 0.250, 0.204, and 0.350 mg L−1, while its insecticidal LC50 values against black bean aphid were 0.150, 0.070, and 0.120 mg L−1, respectively. These substituents provided some hints for further investigation on structure modification.

The formation of oil-in-water (O/W) nano-emulsions suitable for pesticidal application has been studied in water/mixture of non-ionic surfactant (C12E3) and anion surfactant (MAPK)/oil (bifenthrin dissolved in dimethylbenzene) systems. The nano-emulsions with constant oil concentration were prepared by using high-energy emulsification methods. Effects of surfactant ratio and total surfactant concentration on the mean droplet size and size distribution of the emulsions were measured by dynamic light scattering. The stability of nano-emulsions prepared with different surfactant ratios of MAPK and C12E3 was tested by two methods: by measuring the change in droplet size as a function of time using dynamic light scattering and by multiple light scattering. The results showed the data acquired by the short-term scan using multiple light scattering technique corresponded with the droplet size variations measured by dynamic light scattering. The optimum concentration and mixing ratio of the two surfactants for the bifenthrin oil-in-water nano-emulsion was 10 wt% and 6:4 (MAPK to C12E3) and the quality indicators of this nano-emulsion were up to standard according to FAO standards.Graphical abstractEffects of surfactant ratio on droplet size and poly-dispersity index of nano-emulsions and Turbiscan LAb spectra showing delta backscattering (%) as a function of sample height (0–42 mm) and time (from 0:04 to 2:00 d) for nano-emulsions prepared with different mixing ratios of MAPK and C12E3.Highlights► Oil-in-water nano-emulsions suitable for pesticidal application were prepared using anion–nonionic mixed surfactants. ► Figure out the relationship between the mixing ratio, total surfactant concentration and the stability of nano-emulsions. ► Droplet size variations of emulsions prepared with different mixing ratios of MAPK and C12E3 were tested by two methods. ► Data acquired by the multiple light scattering technique accorded with the result measured by dynamic light scattering. ► Multiple light scattering technique could be used for quickly estimating the droplet size variations of nano-emulsions.

A high performance liquid chromatography (HPLC) coupled to electrospray ionisation tandem mass spectrometry (MS/MS) method was described for the residue detection of chrysoidine in yellow-fin tuna in the present study. Samples were cleaned up with solid phase extraction (SPE) cartridge, and then injected into HPLC for separation. Multiple-reaction monitoring (MRM) was applied for quantitative determination. Results showed that the low limit of detection (LOD) of the method was 1.25 × 10−12 g, and the low limit of quantification (LOQ) was 0.42 μg/L. The standard calibration curve was y = 2333.9x −845 (r2 > 0.99) with the linear range of 0.63–100 μg/L. The average recoveries of chrysoidine ranged from 86.0% to 108.0% when the spiked concentration was from 0.5 μg/kg to 20 μg/kg. And the developed method also showed the good test precisions (RSD%: 4.38–14.27%).

A broad-selective monoclonal antibody (Mab) for organophosphorus (OP) pesticides was raised using heterologous indirect enzyme-linked immunosorbent assay (ELISA) to screen hybridomas. On the basis of this Mab, five coating antigens were used to develop homologous and heterologous indirect competitive ELISAs. With the most suitable competitor, a sensitive and broad-selective ELISA was developed. The IC50 values were estimated to be 20.32 ng/mL for parathion, 21.44 ng/mL for methyl-parathion, 42.15 ng/mL for fenitrothion, and 58.85 ng/mL for isocarbophos. Spike recoveries were between 70.52 and 103.27% for the detection of single pesticide residues of the four OP pesticides in purple-clayed paddy soil. Moreover, the chosen ELISA was then applied to the detection of mixtures of parathion and methyl-parathion in soil samples. The average recovery and coefficient of variation were 80.91 and 4.82%, respectively. Results proved that this broad-selective ELISA would be useful for the multiresidue determination of OP pesticides.

The present study developed an improved analytical method for simultaneous quantification of seven neonicotinoids in food by ultraperformance liquid chromatography combined with electrospray ionization triple quadrupole tandem mass spectrometry (UPLC−MS/MS) under the multiple reaction monitoring (MRM) mode. The optimization of extraction, cleanup, UPLC separation and MS/MS parameters of analytes were especially focused on. The low limits of quantification (LOQs) of neonicotinoids ranged from 0.1 to 6 μg kg−1. Meanwhile, reasonable recoveries (65−120%) of seven neonicotinoids for food including apple, cabbage, potato, rice, tea, milk, chicken, pork and egg were demonstrated in different spiked levels within their respective linear range (0.025−150 μg kg−1). The developed analytical method would be appropriate for the routine, high throughput, high sensitivity quantification of seven neonicotinoids using simple sample pretreatment.

Eight new 13-O-aminocarbonylivermectin aglycones and 4′-O-aminocarbonylivermectin monosaccharide were synthesized from ivermectin aglycone and ivermectin monosaccharide by the selective protection of C5-OH group. Their bioactivities were evaluated against spider mites (Tetranychus cinnabarinus), aphid (Aphis fabae) and orlental armyworm (Mythimma sepatara). Their structures were confirmed by 1H NMR, MS.

Oxadiargyl is a commonly used herbicide in China. We developed a simple, fast, and high-throughput method employing gas chromatography with electron capture detector to determine oxadiargyl residues in food samples (rice, straws) and environmental samples (soil, water). Samples were prepared by a modified QuEChERS procedure. In this method, acetonitrile was used as the extracting solvent. The purifying step was omitted when the chromatographic conditions were optimized. Recoveries ranged from 82.9 to 112.0% for oxadiargyl in all samples, with relative standard deviation values lower than 6.2% at 0.01 mg/kg fortified concentration level.

Amphibian populations are decreasing in size due to environmental stressors in most areas of southern China. Pesticides are known to be a group of potential stressors to amphibians, especially in agricultural ecosystems. Profenofos, an organophosphate insecticide and acaricide, is widely used for controlling insect pests in China. The aim of this study is to evaluate the acute lethality and genotoxicity of profenofos to amphibian under controlled conditions. Results showed that profenofos was highly lethal to tadpoles of Rana spinosa, with 50% lethal concentration (LC50) values of 1.59, 1.14, 0.77, and 0.58 mg l−1 at 24, 48, 72, and 96 h, respectively. DNA damage of erythrocytes was observed by alkaline single-cell gel electrophoresis assay at all tested sublethal concentrations. The study also showed, by micronucleus test, that profenofos at moderate to high sublethal concentration might have genotoxicity to the tadpole after 96 h exposure. Furthermore, based on our results, it is suggested that the alkaline single-cell gel electrophoresis assay could be used as a screening tool for biomonitoring of pesticide contamination in aquatic systems or agricultural ecosystems.

A specific monoclonal antibody (McAb) for parathion was produced. Based on this McAb, a battery of competitors as coating antigens were used to develop homologous and heterologous indirect competitive enzyme-linked immunosorbent assays (ELISAs) for parathion. The relationship between the heterology degree of the competitor and the sensitivity of the corresponding immunoassay was investigated. Results showed that, when the specific McAb was used in the ELISA experiment, competitors should have a certain degree of homology with the immunizing hapten for immunoassays, and the best performance occurred when the competitor hapten was highest heterologous to the target analyte. With the most suitable competitor, a sensitive and selective ELISA was developed. The IC50 value of the ELISA was 2.94 ng/ml with a detection limit (IC20) of 0.70 ng/ml. The average recoveries of parathion in spiked water, soil, cucumber and rice were 88.09%, 93.15%, 91.37% and 83.42%, respectively.

Using a simple test for rapid identification and quantification of pesticide multiresidues in food and environmental samples is a long-cherished approach for practical monitoring purposes. Here two gold-based lateral-flow strips (strip A and strip B) were investigated for simultaneous detection of carbofuran and triazophos. For the strip A format, a bispecific monoclonal antibody (BsMcAb) against both carbofuran and triazophos was employed to prepare the immunogold probe. For the strip B format, anti-carbofuran monoclonal antibody (McAb) and anti-triazophos McAb separately labeled with colloidal gold were combined as detector reagents. By comparison of visual results from pesticide standard tests between the two formats, the strip B assay manifested higher sensitivities for both pesticides. Analysis of spiked water samples by the preferable strip indicated that the detection limits for carbofuran and triazophos were 32 and 4 μg/L, respectively. The strength of the portable one-step strip assay was in the simultaneous screening for two pesticides within a short time (8–10 min) without any equipment.

A heterologous direct competitive enzyme-linked immunosorbent assay (ELISA) for parathion residue determination is described based on a monoclonal antibody and a new competitor. The effects of several physicochemical factors, such as methanol concentration, ionic strength, pH value, and sample matrix, on the performance of the ELISA were optimized for the sake of obtaining a satisfactory assay sensitivity. Results showed that when the assay medium was in the optimized condition (phosphate buffer solution [PBS] containing 10% [v/v] methanol and 0.2 mol/L NaCl at a pH value of 5.0), the sensitivity (estimated as the IC50 value) and the limit of detection (LOD, estimated as the IC10 value) were 1.19 and 0.08 ng/ml, respectively. The precision investigation indicated that the intraassay precision values all were below 10% and that the interassay precision values ranged from 4.89 to 19.12%. In addition, the developed ELISA showed a good linear correlation (r2 = 0.9962) to gas chromatography within the analyte’s concentration range of 0.1 to 16 ng/ml. When applied to the fortified samples (parathion adding level: 5–15 μg/kg), the developed ELISA presented mean recoveries of 127.46, 122.52, 91.92, 124.01, 129.72, 99.37, and 87.17% for tomato, cucumber, banana, apple, orange, pear, and sugarcane, respectively. Results indicated that the established ELISA is a potential tool for parathion residue determination.

Three ELISA formats, antigen coated, antibody coated and the second antibody coated for the determination of carbofuran were investigated with conjugations including hapten–BSA, hapten–OVA, hapten–HRP and anticarbofuran IgG–HRP. Results showed that the second antibody-coated method of ELISA had a better performance in the establishment of standard curves and detection of carbofuran residue in vegetables samples. The sensitivity for detection, the I50 value was 36.1 ng/ml at a practical working concentration range from 3.44 to 380.1 ng/ml and the limit of detection for carbofuran was 3.44 ng/ml. The average recoveries of determination for carbofuran spiked in cabbage, lettuce, carrot, winter fragrant-flowered garlic, bamboo shoot and green soy bean were 85.24%, 101.8%, 103.6%, 90.52%, 106.9% and 94.08%, respectively. Additional analyses confirmed that the results given by the ELISA method was in agreement with those of the gas chromatography (GC) method.

Environmental and food safety issues now are recognized internationally, and pesticide residues play key roles as environment and food pollutants. It is crucial to develop methods for rapid determination of pesticide residues in environments and foods. A one-step strip based on nanocolloidal-gold-labeled monoclonal antibodies for detection of triazophos residue was developed. The nanocolloidal gold, with an average particle diameter of 25 nm (G25), was labeled to an antitriazophos monoclonal antibody. This conjugate was dispensed on the conjugate pad of a porous glass fiber. Ovalbumin hapten and goat anti-mouse IgG were dispensed on the nitrocellulose membrane and served as the test line (T-line) and control line (C-line), respectively. After conditions optimization, the one-step strip was finally developed for the residue determination of triazophos. The limit of detection (LOD) of the strip was 4 ng/mL for standard. The detection was not affected by the pH of the liquid sample but low total ion concentration will induce illegible C-line and T-line. The LOD for spiked samples of soil and water was 5 ng/mL, with run time of no more than 10 min.

A novel procedure for parathion hapten design is described. The optimal antigen for parathion was selected after molecular modeling studies of six types of potentially immunizing haptens with the aim to identify the best mimicking target analyte. Heterologous competitive indirect enzyme-linked immunosorbent assay (ELISA) was developed after screening a battery of competitors as coating antigens. The relationship between the heterology degree of the competitor and the resulting immunoassay detectability was investigated according to the electronic similarities of the competitor haptens and the target analyte. Molecular modeling and principal component analysis were performed to understand the electronic distribution and steric parameters of the haptens at their minimum energetic levels. The results suggested that the competitors should have a high heterology to produce assays with good detectability values. An indirect competitive ELISA was finally selected for further investigation. The immunoassay had an IC50 value of 4.79 ng mL−1 and a limit of detection of 0.31 ng mL−1. There was little or no cross-reactivity to similar compounds tested except for the insecticide parathion-methyl, which showed a cross-reactivity of 7.8%.

A multi-determinant artificial antigen was prepared by haptens of four pesticides (chlorpyrifos, triazophos, carbofuran and parathion methyl) conjugating to the carrier protein BSA in turn. Male New Zealand white rabbits were immunized with this multi-determinant immunogen to produce the polyclonal antibodies (PAbs), which can recognize the four pesticides. The PAbs displayed high level for each relative hapten-OVA conjugate, with the favorable titers of 4.49 × 104, 8.98 × 104, 2.24 × 104 and 1.86 × 104, for CHBu-OVA, THHe-OVA, BFNB-OVA and MP5-OVA, respectively. Characterization studies of the PcAbs showed that it has high affinity and specificity to the four relative pesticides. An indirect competitive ELISA was developed for multi-residue determination. The I50 value for the four pesticides was 0.290, 0.065, 0.582 and 2.824 μg mL−1, with the detection limit (I10) of 0.022, 0.005, 0.015 and 0.115 μg mL−1 for carbofuran, triazophos, chlorpyrifos and parathion methyl, respectively. The linear rang was 0.016–2.000, 0.005–0.500, 0.010–2.000 and 0.063–5.000 μg mL−1, respectively, for carbofuran, triazophos, chlorpyrifos and parathion methyl. Results indicated that, this study provided a new strategy to develop immunoassays through artificial antigen design for pesticides multi-residue determination.

Two hundred isolates ofBotrytis cinerea were collected from greenhouse vegetables between 2003 and 2006 to determine their baseline sensitivity to triadimefone, penconazole, tebuconazole and fenhexamid. Mean values of 50% effective concentrations (EC50) of inhibiting growth were 4.853±5.102, 0.41±0.215, 0.19±0.099 and 0.36±0.891 mgl−1, respectively (mean±SD). Individuals ofB. cinerea in the population differed by a factor (EC50 of the least sensitive isolate/EC50 of the most sensitive isolate) of 6625, 20, 603 and 1800, respectively. Naturally fenhexamid-resistant isolates were detected with an unexpected high frequency of 10% although the pathogen population had never been exposed to this fungicide. The resistance level (mean EC50 of resistant isolates / mean EC50 of sensitive isolates) was 19.5. These naturally resistant isolates also were resistantin vivo, and there was no significant difference in growth rate, conidial production or pathogenicity ability between naturally resistant and wild sensitive isolates. These results indicated that there was a potential risk of practical resistance if fenhexamid was applied alone. Negative cross-resistance was observed between fenhexamid and tebuconazole in 90% of the naturally resistant isolates. Moreover, an obvious synergism of the antifungal activity of fenhexamid by tebuconazole was demonstrated in some of the naturally fenhexamid-resistant isolates.

Bismerthiazol, as a thiadiazole fungicide, is widely used in China. The structure of bismerthiazol shows a close relationship to N,N-methylene-bis (2-amino-1,3,4-thiadiazole) (Bis-A-TDA), which is a teratogen. A few studies have shown that this fungicide acts as an endocrine disruptor in mature rats via disturbance in thyroid hormone homeostasis at a certain dose. Little is known about the effect of pubertal exposure to bismerthiazol on the development in pubertal female rats. Based on the protocol of the 20-Day Pubertal Female Assay, postnatal days (PND) 22 old SD rats were administered with bismerthiazol daily by oral gavage at doses of 0, 10, 20 or 40 mg/kg/day for 20 days. After treatment, the rats were sacrificed for blood collection; the reproductive organs, liver, pituitary, adrenal and thyroid gland were harvested. The results indicated that changes in thyroid endpoints following bismerthiazol administration were decreased serum triiodothyronine (T3) and thyroxine (T4) concentrations, increased thyroid stimulating hormone (TSH) concentrations and the ratios of thyroid gland weights, and produced thyroid gland hyperplasia. No histological changes were observed in the uterus and ovaries; moreover, the age and weight at vaginal opening (VO) were unaffected by bismerthiazol in all treatment groups.These data and changes demonstrate that bismerthiazol is likely a thyroid disrupter in female rat following exposure during development, but does not affect the development of pubertal female rats. Further studies using environmentally relevant doses are needed for hazard identification.

In the present study, the genotoxicity of chlorpyrifos was evaluated in the Chinese toad by using Comet assay and Micronucleus test (MN), as the potential tools for the assessment of genotoxicity. The first step was determined by the acute toxicity of chlorpyrifos. Tadpoles were exposed to the series of relatively high concentrations of chlorpyrifos for 96 h. LC50 values at 24, 48, 72, and 96 h were 3.63, 1.17, 0.82, and 0.80 mg l−1, respectively. Secondly, the Micronucleus test was used for detecting chromosome damage in Chinese toad tadpoles exposed to the sublethal concentrations of chlorpyrifos and methyl methane sulfonate (MMS), which indicated that they induced chromosomal lesion in erythrocytes of Bufo bufo gargarizans tadpoles. Thirdly, the significant (P < 0.05 concentration-dependent increase in DNA damage (as indicated by Tail DNA%, Tail length, Olive tail moment)) were observed in erythrocytes and liver cells of tadpoles exposed to the sublethal concentrations of chlorpyrifos and MMS by Comet assay. To our knowledge, this is the first report to describe the use of B. bufo gargarizans for genotoxicity assessment of chlorpyrifos.

Thiodiazole copper, as a thiadiazole fungicide, is widely used in China. The structure of thiodiazole copper shows a close relationship with N,N-methylene-bis (2-amino-1,3,4-thiadiazole) (Bis-A-TDA), which is a teratogen. A few studies have shown that some of the thiadiazole fungicides act as endocrine disruptors via disturbance in thyroid hormone homeostasis. Little is known about the effect of pubertal exposure to thiodiazole copper on the thyroid in pubertal female rats. Based on the protocol of the 20-day Pubertal Female Assay, we attempt to estimate the possible effects of exposure to thiodiazole copper on thyroid hormone and hepatic enzyme activity in female rats. Postnatal days (PND) 22-old Sprague–Dawley rats were administered with thiodiazole copper daily by oral gavage at doses 0, 4, 10, 20 or 30 mg/kg/day for 20 days. After treatments, the rats were sacrificed for blood collection; the reproductive organs, liver, pituitary, adrenal and thyroid gland were harvested. The results indicated that changes in thyroid endpoints following thiodiazole copper administration decreased serum triiodothyronine (T3) and thyroxine (T4) concentrations, increased thyroid stimulating hormone (TSH) concentrations and the weight of thyroid gland, induced hepatic uridine diphosphate glucuronyl transferase (UDPGT) activities in the highest dose group and produced thyroid gland hyperplasia. No histological changes were observed in uterus and ovaries moreover, age and weight at vaginal opening (VO) were unaffected by thiodiazole copper in all treatment groups.The absolute weights of liver and kidney were found to have decreased significantly in female rats. These data and changes demonstrate that thiodiazole copper is likely a thyroid disrupter in female rat following exposure during development, but doesnot have effect on the development of pubertal female rats. Further studies using environmentally relevant doses are needed for hazard identification.

Saisentong, as a thiadiazole fungicide, is widely used in China. The structure of saisentong shows a closer relationship to N, N-methylene-bis (2-amino-1, 3, 4-thiadiazole) (Bis-A-TDA), which is a teratogen. A few studies have shown that some of the thiadiazole fungicides act as endocrine disruptors via disturbance in thyroid hormone homeostasis. Little is known about the effect of pubertal exposure to saisentong on the development in pubertal female rats. Based on the protocol of the 20-Day Pubertal Female Assay, we attempt to estimate the possible effect of exposure to saisentong on thyroid hormone and hepatic enzyme activity in female rats. Postnatal days (PND) 22 old SD rats were administered with saisentong daily by oral gavage at doses of 0, 5, 10 or 15 mg/kg/day for 20 days. After treatment, the rats were sacrificed for blood collection; the reproductive organs, liver, pituitary, adrenal and thyroid gland were harvested. The results indicated that saisentong administration increased thyroid weight and thyroid stimulating hormone (TSH) concentrations, and induced hepatic uridine diphosphate glucuronyl transferase (UDPGT) activities in the highest-dose group, although not statistically significant.The high dose caused a decrease in weight at vaginal opening (VO), but the age at VO was unaffected by saisentong in all treatment groups. No histological changes were observed in uterus and ovaries. These data and changes demonstrate that saisentong is a potential thyroid disrupter in female rat following exposure during development, but does not affect the development of pubertal female rats.

Butachlor, a chloracetamide herbicide, is widely used in China. In the present study, paired adult male and female zebrafish (Danio rerio) were exposed to various concentrations of butachlor (0, 25, 50 and 100 μg/L) for 30 days, and the effects on reproduction and endocrine disruption were evaluated using fecundity, condition factor (CF), gonadosomatic index (GSI), liver somatic index (LSI), plasma vitellogenin (VTG), sex steroids and thyroid hormone levels as endpoints. Our results showed that the mean fecundity rates were significantly decreased at 50 and 100 μg/L butachlor during the 30-day exposure period. At the end of the exposure period, no significant changes were observed in CF and LSI in both females and males, while GSI was significantly reduced in males at 50 and 100 μg/L butachlor. At 100 μg/L butachlor, plasma testosterone (T) and 17β-estradiol (E2) levels were significantly decreased in females, while plasma VTG level was significantly increased in males. Plasma thyroxine (T4) and triiodothyronine (T3) levels were significantly increased at 50 and 100 μg/L butachlor in males, and at 100 μg/L in females. This work demonstrated that butachlor adversely affected the normal reproductive success of zebrafish, and disrupted the thyroid and sex steroid endocrine systems, which provides the basis for the estimated ecological risk during butachlor exposure.

Chlorpyrifos is one of the most extensively used insecticides in China. The distribution and residues of chlorpyrifos in a paddy environment were characterized under field and laboratory conditions. The half-lives of chlorpyrifos in the two conditions were 0.9–3.8 days (field) and 2.8–10.3 days (laboratory), respectively. The initial distribution of chlorpyrifos followed the increasing order of water < straw < soil, and soil was characterized as the major absorber. The ultimate residues in rice grain were below the maximum residue limit (MRL) with a harvest interval of 14 days. The chronic exposure for chlorpyrifos was rather low compared to the acceptable daily intake (ADI = 0.01 mg/kg bw) due to rice consumption. The chronic exposure risk from chlorpyrifos in rice grain was 5.90% and 1.30% ADI from field and laboratory results respectively. Concerning the acute dietary exposure, intake estimated for the highest chlorpyrifos level did not exceed the acute reference dose (ARfD = 0.1 mg/kg bw). The estimated short-term intakes (ESTIs) were 0.78% and 0.25% of the ARfD for chlorpyrifos. The results showed that the use of chlorpyrifos in rice paddies was fairly safe for consumption of rice grain by consumers.Distribution of chlorpyrifos in paddy under field and laboratory condition.Download high-res image (332KB)Download full-size image

Endocrine-disrupting chemicals (EDCs) in the environment have adverse effects on humans and wildlife. A method based on ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) for the determination of 26 EDCs (including five estrogens, eight androgens, three progestogens, six glucocorticoids, two mineralocorticoids and two thyroid hormones) in fish and water was developed. Various experimental parameters that could affect the extraction efficiencies were investigated in detail. The sample was extracted by a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method with 20 mL of acetonitrile (for fish) or 5 mL of ethyl acetate (for water), and then cleaned-up using an Oasis HLB SPE (solid-phase extraction) cartridge. The analytes were quantified using an isotope-labelled internal standard and recoveries between 69.1% and 120.5% were obtained. The relative standard deviation of inter- and intra-day analyses for all the compounds was below 20%. The detection limits ranged from 0.01 to 0.98 ng mL−1 for water and 0.01 to 9.04 ng g−1 for fish. For real samples, progesterone and trenbolone were detected in zebrafish (Danio rerio) samples at 5.73 ± 0.21 and 7.45 ± 0.34 ng g−1, respectively. There was no target analyte detected in tap-water samples. The developed method would be useful for monitoring EDC abuse in fishery, potential EDC screening and risk assessment in aquatic toxicology.