Daily Archives: May 10, 2013

High water fluoride exposure effects sex hormone binding globulin (SHBG) and testosterone in adult male

Zhou T, Yang R, Li S, Zheng G, Xi Y, Cheng X, Hou J, Cui L, Ba Y. [Influence of water fluoride exposure on sex hormone binding globulin and testosterone in adult male]. Wei Sheng Yan Jiu. 2013 Mar;42(2):241-4.

OBJECTIVE: To explore the influence of water fluoride exposure on sex hormone binding globulin (SHBG) and testosterone in adult male.

METHODS: Cross-sectional study was conducted in three villages of Tongxu county including high fluoride group (HFG), defluoridation project group (DFPG) and control group (CG) based on the fluoride concentration in drinking water. Adult male who were born and raised in the village and aged 18 – 50 years old were recruited using cluster sampling. Fasting blood and morning urine samples were collected. The fluoride levels in drinking water and urine were detected by fluoride-ion selective electrode method. Serum SHBG level was determined using enzyme-linked immunosorbent assay (ELISA). The chemical luminescence immune analysis method was used to detect serum testosterone content.

RESULTS: Serum SHBG level was 47.85 nmol/L in CG, 31.37 nmol/L in DFPG and 24.52 nmol/L in HFG respectively. There were significant difference among of three groups (P < 0.05). Serum testosterone level was 3.69 ng/ml in CG, 4.61 ng/ml in DFPG and 4.83 ng/ml in HFG respectively. Serum testosterone level in HFG was significantly higher than that in CG (P < 0.05). Serum SHBG level in HFG has positive correlation with serum testosterone (r = 0.230, P = 0.049), which has not been observed in DFPG and CG.

CONCLUSIONS: Long-time fluorine exposure may affect serum SHBG and testosterone level in adult male.

Upper limit of sea level rise from Antarctic ice sheet is less than IPCC estimates

Erik R. Ivins, Thomas S. James, John Wahr, Ernst J. O. Schrama, Felix W. Landerer, Karen M. Simon. Antarctic contribution to sea-level rise observed by GRACE with improved GIA correction. Journal of Geophysical Research: Solid Earth. DOI: 10.1002/jgrb.50208

[1] Antarctic volume changes during the past 21 thousand years are smaller than previously thought and here we construct an ice sheet history that drives a forward model prediction of glacial isostatic adjustment (GIA) gravity signal. The new model, in turn, should give predictions constrained with recent uplift data. The impact of the GIA signal on a Gravity Recovery and Climate Experiment (GRACE) Antarctic mass balance estimate, depends on the specific GRACE analysis method used. For the method described in this paper, the GIA contribution to the apparent surface mass change is re-evaluated to be +55 ± 13 Gt/yr by considering a revised ice history model and a parameter search for vertical motion predictions that best-fit the GPS observations at 18 high-quality stations. Although the GIA model spans a range of possible earth rheological structure values, the data are not yet sufficient for solving for a preferred value of upper and lower mantle viscosity, nor for a preferred lithospheric thickness. GRACE monthly solutions from CSR-RL04 release time series from Jan. 2003 through the beginning of Jan. 2012, uncorrected for GIA, yield an ice mass rate of +2.9 ± 29 Gt/yr. The new GIA correction increases the solved-for ice mass imbalance of Antarctica to −57 ± 34 Gt/yr. The revised GIA correction is smaller than past GRACE estimates by about 50 to 90 Gt/yr. The new upper bound to sea-level rise from the Antarctic ice sheet (AIS) averaged over the time span 2003.0 – 2012.0 is about 0.16 ± 0.09 mm/yr.

Click here for full paper (fee).

No warming in Antarctica since records began

screenhunter_59-may-09-18-33 antarctic

Source: Real Science