Bioaccessibility and human health risks of arsenic from geological origin in lateritic red soil on construction land.

Current human health risk assessments of soil arsenic (As) contamination rarely consider bioaccessibility (IVBA), which may overestimate the health risks of soil As. The IVBA of As (As-IVBA) may differ among various soil types. This investigation of As-IVBA focused As from geological origin in a typical subtropical soil, lateritic red soil, and its risk control values. The study used the SBRC gastric phase in vitro digestion method and As speciation sequential extraction based upon phosphorus speciation extraction method. Two construction land sites (CH and HD sites) in the Pearl River Delta region were surveyed. The results revealed a high content of residual As (including scorodite, mansfieldite, orpiment, realgar, and aluminum arsenite) in the lateritic red soils at both sites (CH: 84.9%, HD: 91.7%). The content of adsorbed aluminum arsenate (CH: 3.24%, HD: 0.228%), adsorbed ferrum arsenate (CH: 8.55%, HD: 5.01%), and calcium arsenate (CH: 7.33%, HD: 3.01%) were found to be low. The bioaccessible As content was significantly positively correlated with the As content in adsorbed aluminum arsenate, adsorbed ferrum arsenate, and calcium arsenate. A small portion of these sequential extractable As speciation could be absorbed by the human body (CH: 14.9%, HD: 3.16%), posing a certain health risk. Adsorbed aluminum arsenate had the highest IVBA, followed by calcium arsenate, and adsorbed ferrum arsenate had the lowest IVBA. The aforementioned speciation characteristics of As from geological origin in lateritic red soil contributed to its lower IVBA compared to other soils. The oxidation state of As did not significantly affect As-IVBA. Based on As-IVBA, the carcinogenic and non-carcinogenic risks of soil As in the CH and HD sites decreased greatly in human health risk assessment. The results suggest that As-IVBA in lateritic red soil should be considered when assessing human health risks on construction land.

0.05% atropine on control of myopia progression in Chinese school children: a randomized 3-year clinical trial.

AIM: To evaluate the effect of 0.05% atropine on the control of myopia for 2y (phase I) and on spherical equivalent refraction (SER) progression for 1y (phase II) after its withdrawal in Chinese myopic children. METHODS: Totally 142 children with myopia were randomly assigned to the 0.05% atropine group or to the placebo group. In phase I, children received 1 treatment for each eye daily. In phase II, the patients received no treatment. Axial length (AL), SER, intraocular pressure (IOP) and atropine-related side effects were assessed at 6 months' intervals. RESULTS: During phase I, the mean change of SER was -0.46±0.30 D in the atropine group, compared to -1.72±1.12 D in the placebo group (P<0.001). The mean change of AL in the atropine group (0.26±0.30 mm) was significantly shorter than that in the placebo group (0.76±0.62 mm, P=0.002). In addition, in phase II (12mo after the withdrawal of atropine), there was no significant difference in AL change from the atropine group, when compared with that from the placebo group (0.31±0.25 mm vs 0.28±0.26 mm, P>0.05). Furthermore, the change in SER from the atropine group was 0.50±0.41 D, which was significantly lower than 0.72±0.60 D from placebo group, (P<0.05). Finally, there were no statistically significant differences in IOP between the treatment and control groups at any stages (all P>0.05). CONCLUSION: The use of 0.05% atropine for two consecutive years may effectively control elongation of AL and thus progression of myopia, without significant SER progression 1y after atropine withdrawal. Therefore, treatment with 0.05% atropine daily for 2y is effective and safe.