[Children's non-carcinogenic health risk assessment of heavy metals exposure to residential indoor dust around an e-waste dismantling area in South China].

Objective: To evaluate the non-carcinogenic health risk of heavy metals (As, Cd, Cr, Cu, Mn, Pb and Zn) in residential indoor dust for young children around an e-waste dismantling area in South China. Methods: A village around an e-waste dismantling area in South China was selected as a research site in October 2016. Convenience sampling method was used to select 36 houses in the village and 36 dust samples were collected by vacuum cleaner. The concentrations of heavy metals (Cd, Cr, Cu, Mn, Pb and Zn) in each sample were determined and expressed by the average value. Non-carcinogenic health risk assessment was conducted using the US Environmental Protection Agency (EPA) Health Risk Assessment (HRA) model, the American Toxicology and Disease Registry (ATSDR) Target-organ Toxicity Dose (TTD) approach and the ATSDR Binary Weight-of-Evidence (BINWOE) model. Results: The mean ± SD of concentrations of As, Cd, Cr, Cu, Mn, Pb and Zn were (48.90±33.91), (5.95±3.89), (173.57±580.37), (412.71±1 190.00), (612.82±540.70), (297.41±293.22) and (1 052.81±1 156.48) mg/kg, respectively. The HI value of TTD (2.670) and BINWOE (2.933) were higher than the safety threshold of EPA recommended non-carcinogenic health risk. The HI value of TTD and BINWOE were 1.93 and 2.12 times higher than the HI value of HRA (1.386). Conclusion: There was non-carcinogenic health risk of heavy metals (As, Cd, Cr, Cu, Mn, Pb and Zn) via residential indoor dust around the e-waste dismantling area for local children.

The C3-bending levels of the C3-Ar complex studied by optical spectroscopy and ab initio calculation.

The A-X electronic transition of C3-Ar, near 405 nm, has been studied by both laser-induced fluorescence and wavelength-resolved emission techniques. Emission spectra have been recorded from 14 vibrational levels of the A state of C3-Ar; these spectra consist of progressions in the ground state v2 and v4 vibrations (the in- and out-of-plane C3-bending motions, respectively). With increasing bending excitation, these ground state levels shift progressively downwards compared to those of free C3, indicating that the van der Waals complexes are becoming more tightly bound. The level structure of the two vibrations of C3-Ar has been fitted to a perturbed harmonic oscillator model, where the potential function has the form V = V1r cos theta + V2r2 cos 2theta (r is the amplitude of the C3-bending motion and theta gives the orientation of the rare gas atom relative to the plane of the bent C3 molecule). Ab initio calculations have been carried out for C3-Ar at the coupled-cluster singles, doubles (and triples)/correlation consistent polarization valence quadruple-zeta level. They predict that the C3-Ar complex is nearly T shaped at equilibrium, and that as the C3 molecule bends away from the linear configuration, the preferred orientation is "arrow" shaped. From the results of the best fit to the model and the emission spectral intensities, the relative orientation of the out-of-plane pi electron of the A-state complex and the Ar atom has been estimated. No bands of the Ar complex were found near the C3, A-X, (0,0) band, consistent with the fact that the A 1Piu, upsilon = 0 level of free C3 is strongly perturbed by triplet levels. In the excitation spectra of the Ar complex, the bands with upsilonb' > 0 show redshifts of about 16-36 cm(-1) compared to those of free C3, indicating that the A-state complex in these levels is more tightly bonded than the X-state complex.