At a conference presentation last November in Toronto, I referred to the latest edition of Dr. Salby’s textbook, Physics of the Atmosphere and Climate. In it, he explains why man-made CO2 does not control atmospheric CO2. It is a good reference….Several others are picking up on this now (click here).
For more on this book, click here or image below.
Posted in Climate
I believe this study shows the importance of having sufficient nutritional iodine levels rather than the impact of multiple contaminants. This study shows that an abnormality (low iodine) can be made worse by adding other stressors (perchlorate, thiocyanate)….not particularly informative.
Craig Steinmaus, Mark D. Miller, Lara Cushing, Benjamin C. Blount, Allan H. Smith. Combined effects of perchlorate, thiocyanate, and iodine on thyroid function in the National Health and Nutrition Examination Survey 2007–08. Environmental Research, Volume 123, May 2013, Pages 17–24.
Perchlorate, thiocyanate, and low iodine intake can all decrease iodide intake into the thyroid gland. This can reduce thyroid hormone production since iodide is a key component of thyroid hormone. Previous research has suggested that each of these factors alone may decrease thyroid hormone levels, but effect sizes are small. We hypothesized that people who have all three factors at the same time have substantially lower thyroid hormone levels than people who do not, and the effect of this combined exposure is substantially larger than the effects seen in analyses focused on only one factor at a time. Using data from the 2007–2008 National Health and Nutrition Examination Survey, subjects were categorized into exposure groups based on their urinary perchlorate, iodine, and thiocyanate concentrations, and mean serum thyroxine concentrations were compared between groups. Subjects with high perchlorate (n=1939) had thyroxine concentrations that were 5.0% lower (mean difference=0.40 μg/dl, 95% confidence interval=0.14–0.65) than subjects with low perchlorate (n=2084). The individual effects of iodine and thiocyanate were even smaller. Subjects with high perchlorate, high thiocyanate, and low iodine combined (n=62) had thyroxine concentrations 12.9% lower (mean difference=1.07 μg/dl, 95% confidence interval=0.55–1.59) than subjects with low perchlorate, low thiocyanate, and adequate iodine (n=376). Potential confounders had little impact on results. Overall, these results suggest that concomitant exposure to perchlorate, thiocyanate, and low iodine markedly reduces thyroxine production. This highlights the potential importance of examining the combined effects of multiple agents when evaluating the toxicity of thyroid-disrupting agents.
Click here for full paper (fee)
Eschauzier C, Raat KJ, Stuyfzand PJ, De Voogt P. Perfluorinated alkylated acids in groundwater and drinking water: Identification, origin and mobility. Sci Total Environ. 2013 May 18;458-460C:477-485. doi: 10.1016/j.scitotenv.2013.04.066.
Human exposure to perfluorinated alkylated acids (PFAA) occurs primarily via the dietary intake and drinking water can contribute significantly to the overall PFAA intake. Drinking water is produced from surface water and groundwater. Waste water treatment plants have been identified as the main source for PFAA in surface waters and corresponding drinking water. However, even though groundwater is an important source for drinking water production, PFAA sources remain largely uncertain. In this paper, we identified different direct and indirect sources of PFAA to groundwater within the catchment area of a public supply well field (PSWF) in The Netherlands. Direct sources were landfill leachate and water draining from a nearby military base/urban area. Indirect sources were infiltrated rainwater. Maximum concentrations encountered in groundwater within the landfill leachate plume were 1.8μg/L of non branched perfluorooctanoic acid (L-PFOA) and 1.2μg/L of perfluorobutanoic acid (PFBA). Sum concentrations amounted to 4.4μg/L total PFAA. The maximum concentration of ΣPFAA in the groundwater originating from the military camp was around 17ng/L. Maximum concentrations measured in the groundwater halfway the landfill and the PWSF (15years travel distance) were 29 and 160ng/L for L-PFOA and PFBA, respectively. Concentrations in the groundwater pumping wells (travel distance >25years) were much lower: 0.96 and 3.5ng/L for L-PFOA and PFBA, respectively. The chemical signature of these pumping wells corresponded to the signature encountered in other wells sampled which were fed by water that had not been in contact with potential contaminant sources, suggesting a widespread diffuse contamination from atmospheric deposition.
Click here for full paper (fee).
According to the Congressional Budget Office (CBO), a large federal debt could lead to a fiscal crisis where investors no longer want to buy the securities the U.S. Treasury sells to finance the debt. Those folks are right on it, focused like a laser….
Click here for CBO report.