Uptake and accumulation of erythromycin in leafy vegetables and induced phytotoxicity and dietary risks.

Erythromycin (ERY), a widely used macrolide antibiotic, is omnipresent in soil and aquatic environments, which may potentially contaminate food crops but remains to be explored. Two leafy vegetables, pakchoi (Brassica rapa subsp. chinensis) and water spinach (Ipomoea aquatica Forsk.), were grown in laboratory-constructed soil or hydroponic systems to investigate the dynamic accumulation of ERY in edible plants. Results indicate 14C-ERY could be absorbed by water spinach and pakchoi in both systems. Autoradiographic imaging and concentration data of plant tissues suggested that ERY had limited translocation from roots to shoots in these two vegetables. The accumulation level of ERY was similar between the two vegetables in the soil system; but in the hydroponic system, pakchoi had a higher ERY accumulation than water spinach, with the bioconcentration factor of 2.74-25.98 and 3.65-11.67 L kg-1, respectively. The ERY intake via vegetable consumption was 0.01-2.17 ng kg-1 day-1, which was much lower than the maximum acceptable daily intake (700 ng kg-1 day-1), indicating negligible risks of consuming vegetables with roots exposed to ERY at environmentally relevant levels. In addition, ERY was found to cause growth inhibition and oxidative stress to pakchoi, even at low concentrations (7 and 22 µg L-1). This work contributes to a better understanding of plant uptake and translocation of ERY in soils and water, and has important implications for the reasonable evaluation of the implied risks of ERY to vegetables and human health.

Superabsorbent hydrogels coating increased degradation and decreased bound residues formation of carbendazim in soil.

The intensive use of pesticides has caused serious environmental pollution and ecological issues. Thus, it is imperative to explore an efficient way to minimize the pesticide residues and pollution. In the present study, we employed the superabsorbent hydrogels (SHs)-coated pesticide 14C-carbendazim (H-14C-MBC) to investigate the fate of MBC in aerobic soils and to assess the soil microbial state during incubation. The results showed that after coating with SHs, MBC dissipation was improved significantly by 34.2-54.1% compared with that in the control (p<0.05), reducing the persistence of MBC in soil matrix. At 100d, the release of 14C-CO2 was enhanced by 68.0% and 46.6% in neutral loamy soil and basic saline soil, respectively, with respect to the control, resulting in more complete degradation and detoxification of MBC. Additionally, the bound residue in soils, which was associated with potential environmental risk and pollution, was reduced by 15.2% and 14.2%, respectively, compared with that in control soils. The microbial diversity of post-H-14C-MBC soil varied, and microbial composition and abundance remained different from the control, even with the refreshment of soil stability and fertility compared with the blank soil. These results demonstrate the environmental behavior of SHs-coated MBC in soils, and illustrate that SHs-encapsulated formulations would be a promising measure for reducing the soil-residue pollution and environmental risk of pesticides.

Bioaccumulation and bound-residue formation of 14C-decabromodiphenyl ether in an earthworm-soil system.

Decabromodiphenyl ether (DecaBDE) is one of the most frequently detected flame retardants in terrestrial environments. However, the fate of DecaBDE and its transport in an earthworm-soil system with and without a DecaBDE-degrading strain have rarely been evaluated. In this study, 14C-DecaBDE was self-synthesized, and a DBDE-degrading strain, Rhodococcus erythropolis, was used in an earthworm-soil system. DecaBDE showed limited degradation and mineralization after 35days of all treatments. The bound-residue (BR) formation in soil was <2.5% in the system containing earthworms, which was significantly higher (p<0.05) than that observed in the absence of earthworms (<0.45%). DecaBDE could be adsorbed by the earthworms with a BSAF of ≤0.31. The distribution of 14C-DecaBDE concentrations in the earthworm roughly followed the pattern of crop gizzard>digestive system>head>tail>body wall, suggesting that DecaBDE was mainly uptaken through ingestion. Up to 31% of the 14C-DecaBDE in the earthworms was not extractable, revealing that the total concentration of accumulated 14C-DecaBDE was underestimated. The results also showed that the presence of DecaBDE-degrading bacteria did not significantly affect the fate of DecaBDE and its accumulation in earthworms. The study indicates that the conventional assessment of the bioaccumulation and ecological effects of DecaBDE, which is based only on extractable concentrations, may underestimate the risks.

Enantioselective absorption and transformation of a novel chiral neonicotinoid [(14)C]-cycloxaprid in rats.

Neonicotinoid pesticides caused hazardous effects on pollinators and aquatic ecosystem. The new developed chiral cis-neonicotinoid cycloxaprid(CYC) is a highly potent substitute for low toxicity to bees and high efficiency on target-insects, but little is known about the metabolic dynamics of racemic CYC and its 2 enantiomers(SR and RS) in animal models. In this study, chiral separation of (14)C-labeled racemic CYC was performed in high-performance liquid chromatography under optimal conditions. For the first time that the stereoselectivity of the chiral neonicotinoid insecticide CYC was exhibited in rats after single dose oral administration using (14)C-labeled isotope trace technique. Enantioselective behaviors of racemic CYC, SR and RS were observed in blood metabolism, tissue distribution and excretion. The major deposition of (14)C were found in liver, lung, kidney and heart. After 24 h, skin and fat showed a strong bioaccumulation effect, and total excreted urine and feces of CYC, SR and RS were 50.4%, 59.7% and 74.5%, respectively. Enantiomer RS had the fastest absorption and elimination rates, and it was least bioaccumulated in rats. The results provide scientific basis and practical techniques for environmental risk assessment of chiral pesticides, especially neonicotinoids.

[Expression of Egr-1, Nab2 and Cav-1 and its relationship with scar hyperplasia].

Objective To investigate the expression of early growth response protein 1 (Egr-1),NGFI-A binding protein 2 (Nab2) and caveolin 1 (Cav-1) in normal skin,flat-cicatrix and hypertrophic scar,and explore its role in the formation of hypertrophic scar.Methods The expression of Egr-1,Nab2 and Cav-1 protein in 9 normal skin tissues,8 flat-cicatrix tissues and 9 hypertrophic scar tissues were examined with immunohistochemistry SP method and were analyzed statistically.Results The expression of Egr-1 in epidermal cells of hypertrophic scar was significantly higher than that in normal skin and flat scar tissue.The expression of Egr-1 increased in the course of scar proliferation.The distribution patterns of Nab2 were different from Egr-1.The expression of Egr-1 was increased,while expression of Nab2 was decreased.The expression of Cav-1 in normal skin and flat-cicatrix was significantly higher than that in hypertrophic scar.Conclusions The expression of Egr-1,Nab2 and Cav-1 is closely related to the formation of hypertrophic scar,and the up-regulated expression of Egr-1 and the deficient expression of Nab2 and Cav-1 may be the indicators of the progress of formation of hypertrophic scar.