Daily Archives: July 18, 2015

NDMA Study of Cr(VI) Influence is Hypothesis-Generating

Toxicology studies of mixtures have additional complications and their applicability to risk assessment is a developing science. This work should be considered hypothesis generating. In general, conducting risk assessments for individual chemicals yields very conservative results. Addressing mixtures is very speculative and the combinations are endless.

Ma F, Zhang Z, Jiang J, Hu J. Chromium (VI) potentiates the DNA adducts (O6-methylguanine) formation of N-nitrosodimethylamine in rat: Implication on carcinogenic risk. Chemosphere. 2015 Jul 2;139:256-259. doi: 10.1016/j.chemosphere.2015.06.077.

Chromium (VI) [Cr(VI)] and nitrosamines such as N-nitrosodimethylamine (NDMA) exist commonly in the environment. To evaluate the potential influence of Cr(VI) co-exposure on the carcinogenic risk of NDMA, Female Wistar rats were treated with various concentrations of Cr(VI) and/or NDMA via drinking water for 15days and the DNA adducts (O6-methylguanine, O6-MeG) of NDMA in liver tissue was used as a bioindicator. The results showed that Cr(VI) synergistically enhanced the O6-MeG formation, which could lead to an increase in DNA damage and carcinogenic potential. Although Cr(VI) did not alter the CYP 2E1 enzyme activity, it decreased GSH content, which would be an potential mechanism for the potentiated O6-MeG formation by Cr(VI) co-exposure. These results would contribute to the development of quantitative risk assessment of NDMA or even for a group of nitrosamines under environmental mixture exposure.

Extreme Weather Events Typically Result in Infectious Disease Outbreaks

The basic thrust of this article is that extreme weather events result in infectious disease outbreaks. This is a given. We know this from experience as well as science and we should learn what we can from our experiences to minimize or prevent future outbreaks.

But the premise that “Extreme weather events are projected to increase further with the advance of human-driven climate change.” is pure speculation. In fact, the best available science says “human-driven climate change” being referred to here has no relationship to the frequency of extreme weather events.

McMichael AJ. Extreme weather events and infectious disease outbreaks. Virulence. 2015 Jul 13:1-5.

Human-driven climatic changes will fundamentally influence patterns of human health, including infectious disease clusters and epidemics following extreme weather events. Extreme weather events are projected to increase further with the advance of human-driven climate change. Both recent and historical experiences indicate that infectious disease outbreaks very often follow extreme weather events, as microbes, vectors and reservoir animal hosts exploit the disrupted social and environmental conditions of extreme weather events. This review article examines infectious disease risks associated with extreme weather events; it draws on recent experiences including Hurricane Katrina in 2005 and the 2010 Pakistan mega-floods, and historical examples from previous centuries of epidemics and ‘pestilence’ associated with extreme weather disasters and climatic changes. A fuller understanding of climatic change, the precursors and triggers of extreme weather events and health consequences is needed in order to anticipate and respond to the infectious disease risks associated with human-driven climate change. Post-event risks to human health can be constrained, nonetheless, by reducing background rates of persistent infection, preparatory action such as coordinated disease surveillance and vaccination coverage, and strengthened disaster response. In the face of changing climate and weather conditions, it is critically important to think in ecological terms about the determinants of health, disease and death in human populations.

“Carbon Credits” to Finance Household Water Treatment?

The application of “carbon credits” as a commodity to be bought and sold is not a feasible strategy for this or any other application. This approach is not sustainable and will create a bubble that will eventually collapse.

Summers SK, Rainey R, Kaur M, Graham JP. CO2 and H2O: Understanding Different Stakeholder Perspectives on the Use of Carbon Credits to Finance Household Water Treatment Projects. PLoS One. 2015 Apr 30;10(4):e0122894. doi: 10.1371/journal.pone.0122894.

BACKGROUND: Carbon credits are an increasingly prevalent market-based mechanism used to subsidize household water treatment technologies (HWT). This involves generating credits through the reduction of carbon emissions from boiling water by providing a technology that reduces greenhouse gas emissions linked to climate change. Proponents claim this process delivers health and environmental benefits by providing clean drinking water and reducing greenhouse gases. Selling carbon credits associated with HWT projects requires rigorous monitoring to ensure households are using the HWT and achieving the desired benefits of the device. Critics have suggested that the technologies provide neither the benefits of clean water nor reduced emissions. This study explores the perspectives of carbon credit and water, sanitation and hygiene (WASH) experts on HWT carbon credit projects.

METHODS: Thirteen semi-structured, in-depth interviews were conducted with key informants from the WASH and carbon credit development sectors. The interviews explored perceptions of the two groups with respect to the procedures applied in the Gold Standard methodology for trading Voluntary Emission Reduction (VER) credits.
RESULTS: Agreement among the WASH and carbon credit experts existed for the concept of suppressed demand and parameters in the baseline water boiling test. Key differences, however, existed. WASH experts’ responses highlighted a focus on objectively verifiable data for monitoring carbon projects while carbon credit experts called for contextualizing observed data with the need for flexibility and balancing financial viability with quality assurance.

CONCLUSIONS: Carbon credit projects have the potential to become an important financing mechanism for clean energy in low- and middle-income countries. Based on this research we recommend that more effort be placed on building consensus on the underlying assumptions for obtaining carbon credits from HWT projects, as well as the approved methods for monitoring correct and consistent use of the HWT technologies in order to support public health impacts.