Monday, April 14, 2014

Another tool in the war against "superbugs"

Researchers have developed a new polymyxin-like lipopeptide to kill multidrug-resistant microbes (superbugs).  In the past, when facing bacteria that are resistant to antibiotics, doctors could prescribe polymyxins.  Polymyxins are lipopeptides that kill bacteria by binding to a component of the cell wall and disrupting ionic and hydrophobic interactions.  Polymyxin-resistant bacteria have evolved so that they prevent polymyxins from binding with them and causing any disruptions in their cell walls.  By looking at where the resistance comes from structurally (changes in the lipid that affect hydrophobic interactions with the drug), they were able to determine modifications of the polymyxin that would stabilize the binding of the drug to the cell wall. 

We have one more tool in the war between humans and bacteria.  How long before the bacteria figure this one out and evolve yet again…who knows…probably faster than we would like...

Wednesday, April 02, 2014

I’ve Got a BEEF with Sustainability

By Josh Kearns

I’ve had a lot of unpopular ideas. Maybe the all-time most unpopular, though, is this one:

The relatively short trips made by international humanitarian science/engineering and sustainable community development professionals for fieldwork, particularly to far-flung destinations, are almost certainly futile from an environmental sustainability perspective.

Most of us in the international “humanitarian science and engineering,” and “sustainable community development” sectors are professionally concerned with environmental sustainability. We relentlessly flog the rhetoric of “sustainability” for grant seeking and fundraising, in outreach and promotional activities, and in our organizational and institutional self-assessments.

But most of us, myself included, do an awful lot of long-haul air travel for fieldwork, incurring substantial CO2 emissions. This has led me to wonder:

What if the good we do advancing sustainability in our fieldwork gets negated by the CO2 we emit getting there and back again?

I became worried about this after reading climate scientist Kevin Anderson’s article arguing that climate scientists and others who are professionally concerned with sustainability are often a bunch of hypocrites for engaging in so much air travel for conferences, fieldwork, etc., and ought instead to go by train and/or travel less in order to lead by example.

I used to work as a researcher in the development of the Ecological Footprint, a sustainability accounting tool that provides a quantitative metric of sustainability by comparing humanity’s demands for energy, resources, and waste assimilation with the planet’s biological capacity to meet these demands.

 A cartoon conception of the Ecological Footprint.

From my work on the Footprint, I know that people in the "developing world" have much smaller Ecological Footprints than we do in affluent countries such as the US. For example, the average Thai Footprint is about 1/3rd that of the average American. The average Ugandan and Peruvian Footprints are about 1/6th, and the average Haitian about 1/10th that of the average American.

So, recently I began to wonder: How long would a humanitarian scientist/engineer from the affluent world have to live at a local, developing community Ecological Footprint level in order to offset the CO2 they emitted getting out into the field and back home again?

It turns out that this is not too hard to calculate using existing Footprint data. I call the concept the Break Even Ecological Footprint, or “BEEF,” for short. It represents the minimum amount of time a scientist/engineer/development worker has to remain in-country, living with the local community, in order to begin to accrue a net sustainability benefit. Any trip shorter than the BEEF would be futile from a sustainability perspective, as the environmental costs of travel would outweigh the sustainability benefits of living at a lower Ecological Footprint level relative to the affluent home-country lifestyle.

The BEEF concept can thus be applied to gauge the net environmental sustainability benefit (or cost) of a particular work/study trip.

Many humanitarian science and engineering organizations are based in affluent regions and operate on college campuses through the activities of students, faculty, and with professional consultants from big private sector firms. The rigors of the academic calendar and limitations on professionals’ vacation time often greatly restrict the duration of travel by these groups for carrying out humanitarian projects. Trips are planned, for example, over winter break or for a few weeks during summer. Unfortunately, BEEF analysis reveals that trips of this short duration almost always incur a net sustainability deficit. In other words, from an environmental sustainability perspective, these would-be “sustainable development” practitioners should better have stayed home.

Now can you see why my BEEF idea may be record-breakingly unpopular?

If you’ve read this far and you’re still curious to learn more about BEEF analysis, including the calculation methodology and some sample results as well as consideration of criticisms and limitations of the methodology, see my article in Resilience.

You can also visit the Aqueous Solutions website and play around with our interactive BEEF Calculator. We encourage humanitarian engineering and science professionals from affluent countries who are planning to go abroad for fieldwork to use this calculator to assess their trips for potential futility from an environmental sustainability perspective.

And as long as I am pointing fingers, I may as well implicate myself, too.

My fieldwork is located in SE Asia, primarily Thailand and Burma. Using Footprint data for the US and Thailand, I calculate a BEEF of 2.2-11.7 months. That's a wide range, because it takes into account a couple of scenarios depending (1) upon how closely I approximate an average local lifestyle while in the field, and (2) whether a radiative forcing multiplier is applied for CO2 emissions at high altitude.

My current stint in the field is just shy of six months, so I’d better hope that my activities here produce demonstrable, lasting sustainability gains for the local individuals and communities I work with, extending well beyond my own professional life, in order to make it all “worth it” from a bona fide sustainability perspective.

Critically examining my own activities this way underscores the trenchant conclusion that:

If “sustainability” truly is among our most cherished values as professionals and not just a buzzword constantly trumpeted to expedite project funding and social ingratiation, then we must put our professional activities and contemporary lifestyles to rigorous (re-)evaluation, though the implications of doing so may be discomfiting.

What do you think?

*        *        *

Author’s note:        I will be taking a short hiatus from blogging for Chemists Without Borders for the next two weeks. I’m headed to the Kra Isthmus region of SE Burma to work with a small village on water projects and will not have internet access. When I return I hope to have lots photos, stories, and lessons-learned to share!

As usual, you can find me on Facebook, and please “Like” Aqueous Solutions!

Links to my other posts

Wednesday, March 26, 2014

Crowd Funded Low-Tech Cyanide Mitigation, Anyone?

By Josh Kearns

Crowdsourcing is by now thoroughly established as an internet meme. How do I know this? Because I’m aware of it.

Compared to today’s hip and uber-connected Millennials, I’m a hopelessly antiquarian Gen-Xer. I do not and hope to never own a smart phone. (My career aspiration is to eventually go “full Wendell Berry” and refuse to even use a computer.) The only Rock I know is Classic; I don’t even know what “Emo” is (or was); anyway, these days I mostly dig on Bluegrass and Old-Time – you know, “both kinds of music.” I greatly prefer slow travel by train to blasting around the country (and world) stuffed into an airplane. I’ve vowed that my dearly loved ’89 Toyota pickup will be the last car I ever own. (It doesn’t have to last my whole lifetime – just until peak oil drives gas prices out of range of all but the one-percenters…) And I get all giddy whenever a new article comes out in Low Tech Magazine.

With that thumbnail sketch of my corn-pone backwardness, you can understand that by the time an internet trend reaches me, its cutting-edge has long since dulled.

One such contemporary internet meme for which I am late-as-usual to the party is: crowdsourcing support for scientific and research endeavors. I was excited to learn recently about sites such as experiment.com that provide a crowd-funding platform for research projects. This may turn out to be a viable support mechanism for “Chemistry Without Borders” projects, like those we undertake at Aqueous Solutions, which often are difficult to fund through conventional academic channels.

I would be interested to hear from any researchers who have experience with crowd funding their work – what do you think? Pros? Cons? Groovy? Or a total drag?

One thing about doing fieldwork is that practical and applied research projects seem to constantly throw themselves at you. I wrote about one in last week’s post, calling on the (Bio-) Chemists Without Borders community to help us hack a cheap-and-easy field E.coli water tests.

Another nugget (pun intended) I have been mulling over for a while now is how to develop a low-cost treatment system for village water sources impacted by gold mining effluents.

Burma is a country with a lot of mining operations and not a lot of environmental and public health protections.[1] Cyanide – a toxin so potent that it gets its own chapter in The Poisoner’s Handbook[2] – is by far the most common lixiviant (extraction agent) used in gold mining, accounting for about 90% of world production.[3] It’s also used in the recovery of base metal such as copper, lead, and zinc.

Gold mine in Burma.
Image source: http://thevelvetrocket.com/2011/02/23/photos-of-the-day-gold-mining-in-myanmrarburma/

A number of physical and chemical mechanisms influence the fate of cyanide released to the environment, including volatilization, sorption to sediments, oxidation, hydroloysis, photolysis, and biodegradation.[4] Cyanide reacts relatively quickly to for thiocyanate, which is less toxic but much more persistent.[5]

In my work and travels in SE Asia, I’ve encountered numerous individuals and communities concerned about their exposure to mining effluents. These have included complaints of symptoms consistent with exposure to thiocyanate, including skin, eye, and respiratory irritations, nausea and stomach ulcers, and possible neurological effects.

Without epidemiological surveys it is impossible to confirm exposure to cyanide or cyanate species, and the predominant exposure routes (occupational, food and drinking water, dermal exposure e.g. during bathing and clothes washing, etc.). But there is little doubt that mining in Burma heavily impacts water quality at the local and even regional scales, and that proper control measures on cyanide release to the environment are non-existent.

It turns out, though, that many garden-variety indigenous microbes are capable of uptake, conversion, sorption, and/or precipitation of the cyanide, cyanate, and thiocyanate.[3] Microbial species living in mine tailings piles can become acclimatized to elevated cyanide and thiocyanate. Some species, for example the ubiquitous Pseudomonas, are capable of using cyanide and thiocyanate as their source of carbon and nitrogen and are particularly effective at degradation.

A variety of fixed-bed bioreactors for cyanide/thiocyanate degradation have been developed and tested at the lab, pilot, and full scale with encouraging results.[5] One study found activated carbon to be a favorable biofilm support medium, due to its high porosity and surface area for microbial colonization, and its capacity for adsorption of cyanide and thiocyanate complexes.[6]

This has led me to wonder if we could develop a low-cost fixed-film bioreactor using locally generated adsorbent biochar as the support medium, and a cyanide-acclimated microbial inoculum harvested from local gold mill tailings.

It’s a tough question whether such a system could produce drinking-water-quality-water, especially in the case of source waters that are very heavily impacted by mining effluents and therefore are likely to contain also a host of toxic metals. Although, thiocyanate readily forms complexes with many transition metals, so some metals removal may also be achievable through co-precipitation. Furthermore, biochars have also been demonstrated as effective for some uptake of some heavy metals.[7]

Could the water be made safe for drinking and food preparation is thus a totally open – and difficult – question. In my experience, though, many affected communities have worked to secure alternative sources of water for consumption, but still rely on mining impacted waters for bathing, personal hygiene, and clothes washing. A cost-effective treatment system could, therefore, alleviate dermal exposures, or, for example, provide sufficiently detoxified water for raising fish or watering livestock.

Anyway, just some ideas that come up in day-to-day activities here in the village. I wonder if we should test the crowd-funded-science-research waters. What do you think? Anyone want to team up on this project?

As usual, you can find me on Facebook, and please “Like” Aqueous Solutions!

Links to my other posts


[1] At What Price? Gold Mining In Kachin State, Burma. Images Asia & Pan Kachin Development Society, November 2004. [http://www.ibiblio.org/obl/docs/gold%20pdf1.pdf]

Vrieze P, Naing Zaw H. In Tenasserim hills, rise in mining threatens communities. The Irrawaddy, Wednesday, February 5, 2014. [http://www.irrawaddy.org/feature/tenasserim-hills-rise-mining-threatens-communities.html]

[2] Blum D. The Poisoner’s Handbook: Murder and the Birth of Forensic Medicine in Jazz Age New York. Penguin, pubs. 2011. The book has also been made into a PBS film: http://www.pbs.org/wgbh/americanexperience/films/poisoners/

[3] Akcil A., Mudder T. Microbial destruction of cyanide wastes in gold mining: process review. Biotechnology Letters 25: 445–450, 2003.

[4] ATSDR Toxicological Profile for Cyanide. [http://www.atsdr.cdc.gov/toxprofiles/tp8-c6.pdf]

[5] Gould WD, King M, Mohapatra BR, Cameron RA, Kapoor A, Koren DW. A critical review on destruction of thiocyanate in mining effluents. Minerals Engineering 34 (2012) 38–47.

[6] Dictor MC, Battaglia-Brunet F, Morin D, Bories A, Clarens M. Biological treatment of gold ore cyanidation wastewater in fixed bed reactors. Environmental Pollution, Vol. 97, No. 3, pp.287-294.

[7] Mohan D, Sarswat A, Ok YS, Pittman CU. 2014. Organic and Inorganic Contaminants Removal from Water with Biochar, a Re- newable, Low Cost and Sustainable Adsorbent- a Critical Review. Bioresource Technology (in press).