Occurrence and Health Risks of Heavy Metals in Drinking Water of Self-Supplied Wells in Northern China.

Self-supplied wells, an important water resource in remote and scattered regions, are commonly deteriorated by environmental pollution and human activity. In this study, 156 self-supplied well-water samples were collected from remote and scattered areas of Inner Mongolia (NMG), Heilongjiang (HLJ), and the suburbs of Beijing (BJ) in Northern China. Twenty-four heavy metals were identified by using the inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-optical emission spectrometry (ICP-OES), and the associated human health risks were assessed by using standards of the US Environmental Protection Agency (US EPA). The concentrations of four heavy metals (As, Fe, Mn, and Tl) in HLJ, one heavy metal (Tl) in BJ, and ten heavy metals (Al, As, B, Cr, Fe, Mn, Mo, Se, Tl, and Zn) in NMG exceeded the limits set by China or the World Health Organization (WHO). The total carcinogenic risk (TCR) and total non-carcinogenic risk (THQ) exceeding set limits mainly occurred in NMG, compared to HLJ and BJ. Moreover, As accounted for 97.87% and 60.06% of the TCR in HLJ and BJ, respectively, while Cr accounted for 70.83% of the TCR in NMG. The TCR caused by Cd in all three areas had a negligible hazard (<10-4). As accounted for 51.11%, 32.96%, and 40.88% of the THQ in HLJ, BJ, and NMG, respectively. According to the results of the principal component analysis, heavy metals in well water from HLJ and NMG mainly originated from mixed natural processes and anthropogenic sources, whereas, in BJ, most heavy metals probably originated from natural sources. In the future, long-term monitoring of heavy metals in water from self-supplied wells should be conducted for an extensive range of well-water sites, and well water with high As contamination should be monitored more and fully assessed before being used as a drinking-water source.

[Estrogen Receptor Subtype-mediated Luciferase Reporter Gene Assays for Determining (anti) Estrogen Effect of Chemicals].

OBJECTIVE: To establish gene assays for determining (anti) estrogen effect of environmental chemicals; and to compare the reactivity and sensitivity of two assays with different estrogen subtype. METHODS: Human estrogen receptor a (hERalpha) and hERbeta mediated reporter gene assays employing firefly luciferase (Luc) were developed. The expression plasmid hERalpha or hERbeta was constructed and transiently co-transfected into LLC-MK2 cells with pERE-minP-Luc2P reporter plasmid and the control plasmid pGL4.74. Estradiol (E2) and diethylstilbestrol (DES) served as positive test substances to verify the performance of the assays. The effectiveness of the assays for detecting anti-estrogenic activity was tested using 10(-5) mol/L ICI 182, 780 under different concentrations of E2. The performance of the two subtype-mediated assays was verified and compared using bisphenol A (BPA) and genistein (GS). RESULTS: The hERalpha mediated assay found expression of reported gene at 1.9 x 10(-11) mol/L E2; and the largest luciferase activity was shown at 10(-8) mol/L E2, resulting in 30.7-fold of vehicle control. The hERbeta mediated assay found expression of reporter gene at 2.2 x 10(11) mol/L E2, and the largest luciferase activity was shown at 10(-8) mol/L E2, resulting in 14.4-fold of vehicle control. ICI 182, 780 inhibited estrogenic activity of E2 significantly. In both assays, E2 failed to induce luciferase activity without hER-pcDNA3.1. BPA and GS induced luciferase activity. CONCLUSION: Both assays have high sensitivity and reproducibility for detecting (anti) estrogen effect. The pGL4-based hERbeta has lower sensitivity than the hERalpha- mediated reporter gene assay. BPA shows stronger estrogenic activity than GS in hERalpha mediated reporter gene assay; whereas, GS shows stronger estrogenic activity than BPA in hERbeta mediated reporter gene assay.