Tag Archives: aquatic toxicology

University of Missouri and the US Geological survey study carbon nanotubes in aquatic environments

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The University of Missouri’s Aug. 22, 2012 news release (by Timothy Wall) announces the result of a carbon nanotube study in aquatic environments,

A joint study by the University of Missouri and United States Geological Survey found that they [carbon nanotubes or CNTs] can be toxic to aquatic animals. The researchers urge that care be taken to prevent the release of CNTs into the environment as the materials enter mass production.

“The great promise of carbon nanotubes must be balanced with caution and preparation,” said Baolin Deng, professor and chair of chemical engineering at the University of Missouri. “We don’t know enough about their effects on the environment and human health. The EPA and other regulatory groups need more studies like ours to provide information on the safety of CNTs.”

CNTs are microscopically thin cylinders of carbon atoms that can be hundreds of millions of times longer than they are wide, but they are not pure carbon. Nickel, chromium and other metals used in the manufacturing process can remain as impurities. Deng and his colleagues found that these metals and the CNTs themselves can reduce the growth rates or even kill some species of aquatic organisms. The four species used in the experiment were mussels (Villosa iris), small flies’ larvae (Chironomus dilutus), worms (Lumbriculus variegatus) and crustaceans (Hyalella azteca).

“One of the greatest possibilities of contamination of the environment by CNTs comes during the manufacture of composite materials,” said Hao Li, associate professor of mechanical and aerospace engineering at MU. “Good waste management and handling procedures can minimize this risk. Also, to control long-term risks, we need to understand what happens when these composite materials break down.”

I found the abstract for the team’s paper gave a good overview of how the research was conducted,

Carbon nanotubes (CNTs) are hydrophobic in nature and thus tend to accumulate in sediments if released into aquatic environments. As part of our overall effort to examine the toxicity of carbon-based nanomaterials to sediment-dwelling invertebrates, we have evaluated the toxicity of different types of CNTs in 14-d water-only exposures to an amphipod (Hyalella azteca), a midge (Chironomus dilutus), an oligochaete (Lumbriculus variegatus), and a mussel (Villosa iris) in advance of conducting whole-sediment toxicity tests with CNTs. The results of these toxicity tests conducted with CNTs added to water showed that 1.00 g/L (dry wt) of commercial sources of CNTs significantly reduced the survival or growth of the invertebrates. Toxicity was influenced by the type and source of the CNTs, by whether the materials were precleaned by acid, by whether sonication was used to disperse the materials, and by species of the test organisms. Light and electron microscope imaging of the surviving test organisms showed the presence of CNTs in the gut as well as on the outer surface of the test organisms, although no evidence was observed to show penetration of CNTs through cell membranes. The present study demonstrated that both the metals solubilized from CNTs such as nickel and the “metal-free” CNTs contributed to the toxicity.

Here’s the full citation and a link to the paper,

Toxicity of carbon nanotubes to freshwater aquatic invertebrates by Joseph N. Mwangi, Ning Wang, Christopher G. Ingersoll, Doug K. Hardesty, Eric L. Brunson, Hao Li, and Baolin Deng in Environmental Toxicology and Chemistry, Volume 31, Issue 8, pages 1823–1830, August 2012

For anyone who’s curious about what carbon nanotubes look like, here’s an image provided by the University of MIssouri,

Carbon Nanotubes Credit: Shaddack, Wikimedia Commons
Multi-walled carbon nanotubes. 3-15 walls, mean inner diameter 4nm, mean outer diameter 13-16 nm, length 1-10+ micrometers. Black clumpy powder, grains shown, partially smeared on paper. Scale in centimeters.

I could have included a larger version of the image but, given that we’re talking about the nanoscale, the smaller image seems more appropriate.

New research on nanoscale titanium dioxide shows toxic effects on marine life

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Up till now, nanoscale titanium dioxide in water has not been viewed as toxic to marine life. A newly released study by researchers from  the University of California (UC) Center for Environmental Implications of Nanotechnology (UC CEIN) in the Jan. 20 in the journal PLoS ONE suggests otherwise. From the Jan. 24, 2012 news release on EurekAlert,

“Previous experiments have suggested that TiO2 does not affect aquatic organisms, but these experiments used artificial lighting that generated much lower levels of UVR than sunlight,” Miller [lead author and assistant research biologist Robert Miller] explains. “In these new experiments, we used lights simulating natural sunlight.”

But now, the authors say, “We show that relatively low levels of ultraviolet light, consistent with those found in nature, can induce toxicity of TiO2 nanoparticles to marine phytoplankton, the most important primary producers on Earth.

So, the relatively low levels of ultraviolet light in natural sunlight can induce toxicity in titanium dioxide nanoparticles. Here’s the reason for the concern,

“Application of nanomaterials in consumer products and manufacturing is quickly increasing, but there is concern that these materials, including nanoparticles, may harm the environment,” says Miller. “The oceans could be most at risk, since wastewater and factory discharges ultimately end up there.”

In all of the kerfuffle that the Friends of the Earth (FoE) and The ETC Group (and I assume others as well) have made over nanoscale ingredients in sunscreens they seem to have ignored the impact that these ingredients, when washed off our skin and into our water supply, may have on aquatic life.  I wonder if that will matter in the end. I mean if it turns out that nanoscale titanium dioxide is going to kill/damage “… the most important primary producers on Earth”, does it matter if FoE and the others succeed in mobilizing opposition to its use for what most experts might consider the wrong reasons.

Cadmium nanomaterials and biomagnification in the food chain

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Given the recent uproar over cadmium in our local (British Columbia) oysters, this new study about nanoparticles formed from cadmium selenide and their possible absorption into the aquatic food chain caught my attention. From the Dec. 20, 2010 news item on physorg.com,

“We already knew that the bacteria were internalizing these nanoparticles from our previous study,” Holden [Patricia] said. “And we also knew that Ed (Orias) and Rebecca (Werlin) were working with a protozoan called Tetrahymena and nanoparticles. So we approached them and asked if they would be interested in a collaboration to evaluate how the protozoan predator is affected by the accumulated nanoparticles inside a bacterial prey.” Orias and Werlin credit their interest in nanoparticle toxicity to earlier funding from and participation in the University of California Toxic Substance Research & Training Program.

The scientists repeated the growth of the bacteria with quantum dots in the new study and and coupled it to a trophic transfer study –– the study of the transfer of a compound from a lower to a higher level in a food chain by predation. “We looked at the difference to the predator as it was growing at the expense of different prey types –– ‘control’ prey without any metals, prey that had been grown with a dissolved cadmium salt, and prey that had been grown with cadmium selenide quantum dots,” Holden said.

What they found was that the concentration of cadmium increased in the transfer from bacteria to protozoa and, in the process of increasing concentration, the nanoparticles were substantially intact, with very little degradation. “We were able to measure the ratio of the cadmium to the selenium in particles that were inside the protozoa and see that it was substantially the same as in the original nanoparticles that had been used to feed the bacteria,” Orias said.

The fact that the ratio of cadmium and selenide was preserved throughout the course of the study indicates that the nanoparticles were themselves biomagnified. “Biomagnification –– the increase in concentration of cadmium as the tracer for nanoparticles from prey into predator –– this is the first time this has been reported for nanomaterials in an aquatic environment, and furthermore involving microscopic life forms, which comprise the base of all food webs,” Holden said.

The scientists involved with the study are also associated with the University of California Center for Environmental Implications of Nanotechnology (UC CEIN).

As for the local oyster/cadmium situation (from a Dec. 14, 2010 article by Larry Pynn, Postmedia News on Canada.com),

Bendell [Leah Bendell, professor specializing in ecotoxicology at Simon Fraser University, BC] said the Canadian consumption advice barely meets international standards and does not take into account that cadmium levels are higher in “hot spots” in popular B.C. oyster-growing areas such as Baynes Sound near Denman Island, Desolation Sound north of Powell River, and Effingham Inlet at Barkley Sound.

…

One study in 2000 found B.C. oysters reached levels as high as 4.9 parts per million, while a 2004-05 study found levels of up to 3.57 parts per million. A workshop sponsored by Simon Fraser University in May estimated current cadmium levels in B.C. oysters at one to four parts per million.

Europe does not allow the importation of oysters containing more than one part per million of cadmium; Hong Kong’s limit is two parts per million.

The BC Centre for Disease Control states that “levels of cadmium are much lower in oysters elsewhere in the world.”

They are advising local oyster lovers to exercise moderation with regard to eating them.

As for biomagnification and cadmium nanoparticles, here’s what the lead scientist suggested,

“In this context, one might argue that if you could ‘design out’ whatever property of the quantum dots causes them to enter bacteria, then we could avoid this potential consequence,” Holden said. “That would be a positive way of viewing a study like this. Now scientists can look back and say, ‘How do we prevent this from happening?’ ” [emphasis mine]

Slime, titanium dioxide, and marine ecosystems

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I have wondered what happens when titanium dioxide nanoparticles in sunscreens wash off. Apparently, I’m not alone. Two scientists in Connecticut are studying marine biofilm (the slimy green stuff) found on rocks and docks at the seaside. According to a news item on Nanowerk,

While swimmers and boaters along any shore consider the slimy green film that coats everything from rocks to docks as a nuisance, University of New Haven (UNH) chemical engineering student Nicole Reardon and Assistant Professor Shannon Ciston, Ph.D. think otherwise. They view the slime, or biofilm, as a complex community that may hold the key to informing humanity of the true environmental impact of the chemical nanoparticles that find their way from area kitchens, baths and garages into Long Island Sound. One such controversial compound is titanium dioxide, which is used to whiten and brighten a multitude of products, including candy, cosmetics, toothpaste and paint.

… Noting that “large” particles of titanium dioxide are considered safe by the FDA, Ciston and Reardon are interested in how nanoparticles of titanium dioxode affect marine ecosystems, particularly in terms of the humble biofilm. Reardon explains that while marine biofilms can be a bother, they are critical players in the oceanic environment. In addition to transforming nitrogen and carbon in ways that positively impact the greater food web, biofilms clean waste water by eating harmful organic matter and can even be used to clean oil and gasoline spills through bioremediation.

I was hoping to find more information about this project on the University of New Haven website but they appear to have sent out a news release only.  Unfortunately, Dr. Shannon Ciston’s webpage doesn’t offer any additional insight and I could not find a webpage for graduate student Nicole Reardon. My guess is that the lack of more information is due to the University of New Haven being a small university with limited resources. Bravo to their communications team for getting this project noticed and I hope to hear more about it as it progresses.

Oil spills, environmental remediation, and nanotechnology

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Oil spills have been on my mind lately as I’ve caught some of the overage about the BP (British Petroleum) oil spill in the Gulf of Mexico. One  leak (the smallest) has been fixed according to a news item on physorg.com

Days of work off the coast of Louisiana with underwater submarines nearly a mile below the surface finally bore fruit as a valve was secured over the smallest of the three leaks and the flow shut off.

The feat does not alter the overall amount of crude spilling into the sea and threatening the fragile US Gulf coast, but is significant nonetheless as the focus can now narrow on just two remaining leaks.

“Working with two leaks is going to be a lot easier than working with three leaks. Progress is being made,” US Coast Guard Petty Officer Brandon Blackwell told AFP.

More than two weeks after the Deepwater Horizon rig exploded, the full impact of the disaster is being realized as a massive slick looms off the US Gulf coast, imperilling the livelihoods of shoreline communities.

The news item goes on to detail how much crude oil is still being lost, the oil slick’s progress, the probable impact on the shoreline and animals, and the other efforts being made to ameliorate the situation.

With all the talk there is about nanotechnology’s potential for helping us to clean up these messes, there’s been no mention of it in the current  efforts as Dexter Johnson over at the IEEE’s (Institute of Electrical and Electronics Engineers)  Nanoclast blog pointed out the other day. From Dexter’s posting which features both a  discussion about patents for nanotechnology-enabled clean up products and an interview with Tim Harper,

So to get a sense of where we really are I wanted to get the perspective of my colleague, Tim Harper (principal of Cientifica), who in addition to being a noted expert on the commercialization of nanotechnologies also has devoted his attention to the use of nanotechnologies in cleantech including its remediation capabilities, leading him to his presentation this week in Australia at the conference Cleantech Science and Solutions: mainstream and at the edge.

“If you are looking for a quick fix from nanotechnology, forget it,” says Harper. “Nanotech is already making an impact in reducing energy, and therefore oil use, it is also being used to create stronger lighter materials that can be used for pipelines, and enabling better sensors for early warning of damage, but in terms of cleaning up the mess, the contribution is minor at best.”

Clearly not the hopeful words that many would have hoped for, and the pity is that it might have been different, according to Harper.

“As with all technologies, the applications take a while to develop,” he says. “If someone had come up with some funding 10 years ago for this specific application then we may have had better tools to deal with it.”

Dexter’s posting about patents and Harper’s comments reminded me of an article by Mason Inman I saw two years ago on the New Scientist website titled, Nanotech ’tissue’ loves oil spills, hates water. From the article,

A material with remarkable oil-absorbing properties has been developed by US researchers. It could help develop high-tech “towels” able to soak up oil spills at sea faster, protecting wildlife and human health.

Almost 200,000 tonnes of oil have been spilled at sea in accidents since the start of the decade, according to the International Tanker Owners Pollution Federation. [This article was posted May 30, 2008]

Clean-up methods have improved in recent years, but separating oil from thousands of gallons of water is still difficult and perhaps the biggest barrier to faster clean ups.

The new water-repellent material is based on manganese oxide nanowires and could provide a blueprint for a new generation of oil-spill cleaners. It is able to absorb up to 20 times its own weight in oil, without sucking up a drop of water.

Unfortunately,

But [Joerg] Lahann [University of Michigan in Ann Arbor, US]  points out that manganese oxide may not be the best material for real-world applications because it could be toxic. He says, though, that the new material “clearly provides a blueprint that can guide the design of future nanomaterials for environmental applications.”

I wonder if they’ve done any research to determine if manganese oxide in the shape and size required to create this nanotech ’tissue’ is toxic. Intriguingly, there was a recent news item on Nanowerk about toxicology research in a marine environment being undertaken.

Led by Dr. Emilien Pelletier, the Institut des Sciences de la Mer de Rimouski at the Université du Québec à Rimouski has obtained an LVEM5 benchtop electron microscope to help them study the short-term and long-term effects of nano-materials on the marine environment.

Dr. Pelletier is the Canada Research Chair in Marine Ecotoxicology. The overall objective of the chair is to understand the impact of natural and anthropogenic stresses on the short-and long-term high-latitude coastal ecosystems to contribute to the conservation, protection and sustainable development of cold coastal marine resources.

Since the news release was written by the company supplying the microscope there is no word as to exactly what Emilien’s team will be researching and how the work might have an impact on other members of the community such as the researchers with the ‘oil-hungry nanotech tissue’ made of nanoscale manganese oxide.

There is as always a political element to all of this discussion about what we could or couldn’t do with nanotechnology-enabled means to clean up oil spills and/or reduce/eliminate our dependence on oil. This discussion is not new as Dr. J. Storrs Hall implies during a presentation being reported in a recent (May 4, 2010) Foresight Institute blog entry by Dave Cronz, PhD. From the posting,

Here I offer my reflections on some of the highlights of the presentation by Dr. J. Storrs Hall of the Foresight Institute, entitled “Feynman’s Pathway to Nanomanufacturing,” and the panel discussion that followed, “How Do We Get There from Here?” Discussions such as these are crucial opportunities to reflect on – and potentially shape – emerging technologies whose destinies are often left to be determined by “market forces.”

Dr. Hall began with an intriguing argument: Feynman’s top-down approach to reaching the nano scale in manufacturing, achieved through a step-down method of replicating and miniaturizing an entire, fully-equipped machine shop in 1:4 scale over and over would yield countless benefits to science, engineering, and manufacturing at each step. These microscopic, tele-manipulated master-slave “Waldos” (named after Heinlein’s 1942 story “Waldo F. Jones”) would get nanotechnology back on track by focusing on machines and manufacturing, since most of our current emphasis is on science at the nano scale. Feynman’s top-down approach to nanoscale manufacturing is missing from the Foresight Institute’s roadmap, according to Hall, “for political reasons.” This raises a fundamental point: science and technology cannot develop independent of the political and social spheres, which pose as many challenges as the technology. Many would argue that social and technological processes are inseparable and treating them otherwise borders on folly. I commend Dr. Hall for offering his argument. It soon became clear that the panelists who joined him after his presentation disagreed. [bolded emphases mine]

…

As Dr. Hall aptly noted it’s not dispassionate calculations but “serendipity: the way science always works.”

I’m in agreement with Dr. Hall, the political and social spheres are inseparable from the scientific and technological spheres. As for “emerging technologies whose destinies  are often left to be determined by market forces”, Dexter’s posting ends with this,

But foresight is not the strong suit of businesses built around short-term profit motives as evidenced by them [BP] not even investing in the remote systems that would have turned the oil well off and possibly avoided the entire problem.

I strongly recommend reading Dexter’s posting to get the nuances and to explore his links.

I’m going to finish on a faint note of hope. There is work being done on site remediation and it seems to be successful, i.e., nonpolluting, less disruptive to the environment, and cheaper.  The Project on Emerging Nanotechnologies (PEN) has a webcast of a presentation titled, Contaminated Site Remediation: Are Nanomaterials the Answer?. You can find my comments about the webcast here (scoll down a bit) and PEN’s Nanoremediation Map which lists projects around the world although most are in the US. It’s incomplete since there is no requirement to report a nanoremediation site to PEN but it does give you an idea of what’s going on. Canada has two sites on the map.

Bee silk; minnows and silver nanoparticles; David Cramb at U of Calgary finds way to measure nanoparticles in bloodstream; Rock Against Prisons

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I had not realized that there’s an international drive to produce artificial insect silk until this morning. According to a news item on Nanowerk,

CSIRO [Australia’s Commonwealth Scientific and Industrial Research Organisation] scientist Dr Tara Sutherland and her team have achieved another important milestone in the international quest to artificially produce insect silk. They have hand-drawn fine threads of honeybee silk from a ‘soup’ of silk proteins that they had produced transgenically.

These threads were as strong as threads drawn from the honeybee silk gland, a significant step towards development of coiled coil silk biomaterials.

“It means that we can now seriously consider the uses to which these biomimetic materials can be put,” Dr Sutherland said.

“We used recombinant cells of bacterium E. coli to produce the silk proteins which, under the right conditions, self-assembled into similar structures to those in honeybee silk.

If I understand this rightly,  ‘tinkering’ with bacterium E. coli makes this a transgenic system and I believe it’s a GEO (genetically engineered organism) and not a GMO (genetically modified organism). In any event, it’s also biomimetic because this process mimics a biological system.

On the practical side of things, insect silk could potentially be used for tough, lightweight textiles and medical applications such as sutures. You can read more about this in the Nanowerk news item.

A Purdue University study has added more evidence that silver nanoparticles are toxic to fish. According to the news item on physorg.com,

Tested on fathead minnows ╨ an organism often used to test the effects of toxicity on aquatic life — nanosilver suspended in solution proved toxic and even lethal to the minnows. When the nanosilver was allowed to settle, the solution became several times less toxic but still caused malformations in the minnows.

“Silver nitrate is a lot more toxic than nanosilver, but when nanosilver was sonicated, or suspended, its toxicity increased tenfold,” said Maria Sepulveda, an assistant professor of forestry and natural resources whose findings were published in the journal Ecotoxicology. “There is reason to be concerned.”

Coincidentally, Dr. David Cramb, director of the Nanoscience Program and professor in the department of Chemistry at the University of Calgary, and his colleagues have published a paper about a new methodology they are developing to measure the impact of nanoparticles (no specifics about which ones) on human health and the environment. From the news release on Eureka Alert, [Mar.4.10 ETA since I think the Eureka doesn’t last long, here’s a link to the same news on Azonano]

Cramb, director of the Faculty of Science’s nanoscience program, and his researchers have developed a methodology to measure various aspects of nanoparticles in the blood stream of chicken embryos. Their discovery is published in the March online edition of Chemical Physics Letters.

“With the boom in nanomaterials production there is an increasing possibility of environmental and/or human exposure. Thus there is a need to investigate their potential detrimental effects,” says Cramb. “We have developed very specialized tools to begin measuring such impacts.”

To close today off, I got a news release from poet Heather Haley (Vancouver, Canada based) about her latest local appearance,

Heather Haley was a member of Vancouver punk bands, the all-girl Zellots and the .45s with Randy Rampage and Brad Kent. Long-lost video of the Zellots will be screened and Heather will interviewed for a live webcast. She will perform poetry from her new collection, “Three Blocks West of Wonderland.” Hope to *see* you there.

ROCK AGAINST PRISONS Live Video Retrospective         Tuesday, March 9, 2010         7:00pm – 11:55pm
Little Mountain Gallery         195 east 26th Ave         Vancouver, BC
On March 9th, the social forces will be mounting an assault on the staid and the bland. From a Punk Rock Swap Meet to a Celebrity Auction, from an ‘umplugged’ stage to a Grand Slam Poetry Karaoke by some of the big stars of 1979, we are getting the Old Gang Together. We review the fabulous footage by doreen grey from the seminal 1979 gig and plan out the 2010 resurgence of the Vancouver Explosion.
Come on out and celebrate Vancouver’s living heritage with those who made it happen: Rabid, Female Hands, Devices, Zellots, Tunnel Canary, AKA, Subhumans. Special appearances. Door Prizes. Live Webcast and Kissing Booth. Fishnet stockings. Oodles of prime swag and fixins. Your every 1979 Punk nightmare come beautifully true.

You can also check out Heather’s latest work on her website.