Saturday, January 5, 2008

On EHS Nano and Water - A DRAFT

I am working on a WATER project right now and am sharing an early draft of the EHS section. Comments are always welcomed.

By the way, I have my office at NCSU now and will be posting regularly. I start teaching a graduate seminar in RISK next Thursday.

POST

We begin with the EHS footprint. This involves examining multiple exposure modalities associated with applied nanoscience and water.

First, we have the consequences of the waste streams generated when producing nanoparticles and using nanoparticles and its effects on potable surface water and in some cases groundwater. These could occur profoundly in the production and disposal ends of the nanoparticle life cycle.

Producing nanoparticles involves the use of chemicals which need disposal and result in quantities of product which either fail to meet product requirements or are the product of cleaning vessels and chambers associated with production. While some significant recycling does occur, there are some disposal issues.

There is very little research undergoing examining the effects of disposal and incineration of these waste stream products. Recent research undertaken by UCSB under a grant from ICON involved remarks indicating that some of these materials are turned over in a subcontract to a waste disposal firm. At a pollution prevention meeting in Washington in 2007 a representative from the waste disposal industry underlined the fact that the disposal and recycling industries have received little or no guidance from regulators.

Nanoparticles have been described as free or bound in a matrix. Presumably free nanoparticles as would occur during packing might be especially problematic for workers while those bound in a matrix such as carbon nanotubes in automobile runners would be less problematic. Nevertheless, there remain some end life cycle challenges when nanoparticles bound in matrices are disposed or recycled. Until there is a body of reliable data we may discover nanoparticles in soil samples as well as surface and groundwater. Our experience with leaking underground storage tanks should provide us a lesson when it comes to disposal of nanoparticles.

Second, we have the consequences of nanoparticles leaching down into groundwater resources from applications to remediate heavily polluted sites and topical applications in the agriculture and forestry industries which can runoff and drain into surface water and freshwater aquifers.

Nanoscale metals can render some chemicals inert and kill some microorganisms. Some research has demonstrated their capacity under certain circumstances to remove some salts and metals as well as decompose some organic pollutants. For example a cyclodextrin polymer has been shown to remove a range of contaminants, including benzene, polyaromatic hydropcarbons, fluorines, nitrogen-containing contaminants, acetone, pesticides, explosives and many others. It could be used for in situ groundwater treatment or for cleaning oil and organic chemical spills.[1]

In addition, research has considered the use of titanium, zinc, and silver to degrade volatile organic compounds. Titanium oxides react to ultraviolet light. “When water comes in contact with titanium oxide and is exposed to light, the chemical breaks down bacterial cell membranes, killing bacteria like the ubiquitous E col.”[2] A titanium dioxide granular media called Adsorbia™GTO™ was field tested in Bangladesh and is marketed by Dow to remove arsenic from water from its combined oxidative and adsorptive properties.[3]

Sulfate reducing bacteria can produce heavy metal particulates. Using bacterial metal-binding proteins a team from Lawrence Livermore National Laboratory and UC Berkeley believe they can clean up heavy metal particulates like zinc sulfide.[4]

In 2007, a new group calling themselves AE Water Treatment™ is using iron nanoparticles and lanthanum chloride to develop new approaches to water treatment and ground water remediation.[5] Adedge Technologies also offers AD33, a nanostructured iron oxide media for the removal of arsenic as well as lead, zinc, chromium, copper, and other heavy metals.[6]

It seems the use of nanoscale zero valent iron (NZVI) can be injected into contaminated water sources for remediation and has been shown to degrade pesticides including DDT and lindane.[7] PARS Environmental manufactures zero-valent iron used for in-situ remediation of microbial and organic contamination in groundwater.[8] The list of common environmental contaminants NZVI could address includes chlorinated methanes, chlorinated benzenes, pesticides, organic dyes, thrihalomethanes, PCBs, arsenic, nitrate, and heavy metals such as mercury, nickel, and silver.[9]

Direct applications of agricultural products involving nanoparticles have been touted to reduce pesticide and water use, improve plant and animal breeding, and create nano-bioindustrial products.[10] The speculation is legion. “Think of a pesticide that would release its pest-killing properties only when it has been igested by the targeted insect and a nanoparticle that could be ingested by chickens and turkeys to remove a common poultry bacterium called campylobacter that causes about 1 million US residents to get sick each year.”[11] In reality, companies such as Monsanto, Syngenta and BASF are developing pesticides enclosed in nanocapsules or made of nanoparticles according to a joint OECD-Allianz Group report.[12] The same Allianz Report adds: “With funding from the US Department of Agriculture (USDA), Clemson University researchers are feeding bioactive polystyrene nanoparticles that bind with bacteria to chickens as an alternative to chemical antibiotics in industrial chicken production” and “One of the USA’s biggest farmed fish companies, Clear Spring Trout, is adding nanoparticle vaccines to trout ponds, where they are taken up by fish.”[13]

For example, a team from Iowa State claim they can use the pores of mesoporous silica nanoparticles to deliver a chemical trigger for gene expression in tobacco plants.[14] Monsanto claims this breakthrough result could find applications in plant biotechnology and might even be used to improve crops in the future.[15]

Applications include smart sensors and smart delivery systems which could help the industry combat viruses and other crop pathogens and increase the efficiency of pesticides and herbicides, allowing lower doses to be used.[16] For example, Syngenta already uses nanoemulsions in one of its pesticide products Primo MAXX®. Called smart delivery system, this approach has attracted major players including LG, BASF, Honeywell, Bayer, Mitsubishi, and Dupont.[17]

Bioindustrial applications, sometimes called particle farming, have been demonstrated by a team at the University of Texas-Austin. For example, alfalfa plants grown in gold rich soil absorb gold nanoparticles through their roots and accumulate these in their tissues. The particles are mechanically separated following harvest.[18]

Since nanomaterials are more biological active than larger versions of the same chemical, the potential for inflammatory and pro-oxidant effects as well as anti-oxidant effects under some conditions they represent a class of materials about which there are many unknowns. How they interact with other nanomaterials and with organic material in the environment must be better understood. Some research has begun. For example, a Canadian research team led by Denis O’Carroll is using experimental conditions that parallel actual field conditions. According to O’Carroll, “there is considerable interest in pumping nanomaterials into the ground where they can flow with groundwater to a contaminated region and convert hazardous chemicals into benign products like ethane and butane.”[19] He expects findings within the next five years. Unfortunately, not enough of this type is research is underway leading the Meridian Institute to warn that “even though nanomaterials with certain coatings may be safe under laboratory conditions, it may be necessary to test these compounds under environmental conditions.”

Third, we have the consequences of nanoparticles from products such as washing machines, as well as industrial applications in agriculture, forestry, and aquaculture that find their way into the water treatment systems. In addition we may have residues of nanoparticles used in the water treatment process itself that could reach consumers.

Let’s begin with the tale of the Samsung Silver Care Health System referring to a suite of Samsung products including air conditioning and refrigerators. What got Samsung into hot water was the heart of the patented Silver Nano Health System technology of Samsung, an electrolysis unit in the washing machine. Silver ions are extracted from a silver plate and delivered during the washing process into the washing water. The silver ions act as an anti-bacterial and work in cooler water so the washer uses less energy. Samsung claims the silver ions will quickly bind to organic matter and become inactive in waste. The water treatment industry was so convinced claiming current treatment being able to remove only 50 to 90 percent of the silver. Silver could affect bacteria used in the waste treatment process. If not, the rest would remain in sludge which is commonly placed on farm land or in landfills. In addition, there is some concern bacteria may develop resistance to silver as well as antibiotics as has been suggested in birds and salmonella.

In America, two groups the National Association of Clean Water Agencies (NACWA) and Tri-TAC a waste treatment group from California wrote to the EPA concerned about this use of silver. In the end, the EPA demanded the INSERT.

In Europe, The German association for the protection of the environment and nature (BUND) alerted consumers on the presence of silver nanoparticles in these washing machines. BUND claimed the silver nano-particles contained in the machine were not tested. They claimed bioassays would have found nano-size silver can deleteriously affect liver and sex cells and the development of nerve cells. They warned Samsung and Media Markt were marketing the new washing machine as particularly health-friendly and for people with allergies and pregnant women.

An article in Eurip.com added that the use of considerable quantities of silver ions would remain in the waste water and make its way into the soil. As highly effective biocides, they could kill bacteria, which are used in biological purification plants, and so disturb waste water purification. In addition, the particles would contribute to the silver load of the sewage sludge, which was no more suitable for the agricultural fertilization afterwards.

Samsung’s response: "…the silver ions only function with the washing machines and are inactive as soon as they arrive in the waste water…. We speak here of only max. 0.05 grams silver per year arriving additionally in the waste water.”

It is unclear whether the silver ions are intentionally engineered nanoparticles with any special properties that might trigger concerns noted above. The washer releases silver ions involving the electro-shaving of two silver plates and no one outside Samsung has any idea what this means. Most experts agree silver ions are not silver nanoparticles for the purposes of assessing its risk profile and Samsung got itself into this controversy by misjudging the marketing value of the nano moniker.

Silver ions are used in brooms, food storage containers, drywall and point for surfaces to reduce mold, curtain coatings in hospitals, wound treatments, and coating for some surgical tools. LG Electronics and Daewoo are selling silver-lines refrigerators and vacuum cleaners. And the sports companies, including Adidas, Polartec, Brooks Sports, ARC Outdoors, have and are ready to mount silver particles as a disinfectant for clothing. Even a Yoga company, Plank, is selling silver particles as a disinfectant in their Cor soap. Some of it will get into water supplies and before we pass on its use, we might want to develop a research database which will allow regulatory agencies to determine how to effectively screen or regulate it.

The same could be said about the agriculture, forestry, and aquaculture industries who are becoming intrigued with applied nanoscience and its capabilities to reduce production expenses, add value, and maximize profitability.

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Indeed, when it comes to cleaning and filtering water the traditional way, “we’ve gotten as far as we can go on the larger scale,” says EPA’s Richard Sustitch.[20] “It’s not black and white” says Mamadou Diallo from Cal Tech’s Molecular Environmental Technology program. “No one wants to drink nanoparticles with their water.”[21] The perceived risks are especially problematic for this industry. As was somewhat evident from the Samsung washer issue, the water industry is typically conservative and risk adverse. Since most water companies are publicly owned, they aren’t allowed to make a profit. And if something went wrong, the water company could be held responsible for a public health crisis says Sustich.[22]

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Fourth, we have the consequences from nanoparticles used as anti-fouling coatings for water traversing vessels and offshore structures including FPSOs (floating production storage and offloading tanks), submerged and insulated pipelines, heat exchangers in desalination or power plants, oceanographic sensors, and swimming pools. Over time, the coatings degrade and are released into freshwater, saltwater, and recreational systems.

Algae and mussels foul submerged structures of all sorts. Algae is nearly everywhere we find water including community pools. Mussels are observable on wharf pilings and on the hulls of vessels. Fouling can be costly. For example, ships with fouled hulls require 40 percent more fossil fuel to travel at the same speed as unfouled vessels.[23]

Currently, organotin compounds are used as biocides for vessels and structures, but they have a formidable toxicity profile and may been banned by the EU in the near future. In addition, the current silicone-base treatment has drawbacks not the least of which is the fragile nature of the coating.

This has opened opportunities for companies like BASF to develop alternative coatings. According to BASF’s Harald Keller, “The nanostructuring of the surface alters the wetting properties and is intended to signal that the site is not suitable for the organisms to settle.” One of the more promising developments involves the use of alumina/titania coatings for salt water vessels to reduce corrosion. The electrodeposition of silanes on roughened titanium is also receiving some notice. Anticipated alternative from polymer blends that segregate to produce a mosaic surface to the use of nanoparticles that moderate surface rugosity.[24] A silicone-based fouling release coating using silicone and nanotubes developed by the University of Mons-Hainaut and Nanocyl promises to be stronger, more robust, and easier to apply.

The EU research project “AMBIO” is investigating how to prevent the buildup of organisms on surfaces under marine conditions, for example on ships' hulls. Scientists from BASF are collaborating on this project with 30 partners from business and science from 14 countries.[25] The EC covered paints of this sort under the Biocidal Products Directive EC 98/8/CE.

There are some much more intimate applications worth considering as well. Pools, both private and commercial, are a huge market. The National Swimming Pool and Spa Institute reports the market consists of approximately eight million pools and four million existing spas and hot tubs worldwide, with an additional 360,000 pools and approximately 260,000 spas and hot tubs being installed on a yearly basis.[26] Loncto et al report nanoscale lanthanum oxycarbonate particles can be used to stop algae buildup in swimming pools by binding with phosphates.[27] For example, Altair Nanotechnologies, a leader in nanotechnology, nanomaterials and material science reported safety and effectiveness of its NanoCheck™ swimming pool algae prevention compound has been validated in independent testing. Altair claims its nano-structured compound works in conventional pool filtration systems is highly insoluble in water and is not a biocide.[28]

These coatings tend to last for one to two years. When they are applied and after they degrade and are reapplied, there will be some incidental or collateral release into the immediate environment. As they degrade, the release would occur while the coating is submerged. Until we have some better idea how the nanoparticle impregnated coatings interact with the freshwater or seawater environments when they are released, we might want to temper the comparative claims being made by the industry and others. While there are some good reasons to believe the nano-alternative might be preferred to both current anti-biofouling compounds as well as the ancillary costs of biofouling, there remain many unknowns.


REFERENCES



[1] Meridian Institute. (2006). Overview and Comparison of Convention Water Nano-Based Treatment Technologies. October 11-12. 26.

[2] Cosier, S. (2006). Big problems, little solutions. Scienceline. September 22. http://scienceline.org/2006/09/22/env-cosier-nanotech/. Accessed August 7, 2007.

[3] Meridian Institute. (2006). Overview and Comparison of Convention Water Nano-Based Treatment Technologies. October 11-12. 31.

[4] Microbes at work cleaning up the environment. (2007). June 14. www.eurekalert.org/pub_releases/2007-06/dlnl-maw061407.php. Accessed June 19, 2007.

[5] American Elements combines nanoparticles, rare earths, and bulk chemical capabilities in launch of new AE Water Treatment Group. (2007). June 13. www.americanelememtns.com\news_6_13_07.htm. Accessed August 7, 2007.

[6] Meridian Institute. (2006). Overview and Comparison of Convention Water Nano-Based Treatment Technologies. October 11-12. 31.

[7] Zhang, W. (2003). Nanoscale iron particles for environmental remediation: An overview. Journal of Nanoparticle Research, 5: 323-332.

[8] Meridian Institute. (2007). Workshop on Nanotechnology Water & Development. 15. http://www.merid.org/nano/waterworkshop/assets/WorkshopSummary.pdf. Accessed August 7.

[9] Meridian Institute. (2006). Overview and Comparison of Convention Water Nano-Based Treatment Technologies. October 11-12. 28.

[10] Analysis of early stage agrifood nanotechnology research and development. (2006). The A to Z of Nanotechnology. March 30. http://www.azonano.com/news.asp?newsID=2044. Accessed March 30, 2006.

[11] Rizzuto, P. (2006). Report says questions need to be addressed on use of nanotechnology in food, livestock. Daily Environment. September 7. Email communication.

[12] Allianz Group. (2005). Opportunities and risks of nanotechnologies. June 13. http://www.oecd.org/dataoecd/37/19/37770473.pdf. Accessed November 12, 2007. 17.

[13] Allianz Group. (2005). Opportunities and risks of nanotechnologies. June 13. http://www.oecd.org/dataoecd/37/19/37770473.pdf. Accessed November 12, 2007. 17-18.

[14] Dume, B. (2007). Porous nanoparticles deliver chemicals into plants. Nanotechweb. May 15. http://nanotechweb.org/particles/news/6/5/14?alert=1. Accessed May 22, 2007.

[15] Porous nanoparticles deliver chemicals into plants. (2007). http://www.monsanto.co.uk/news/ukshowlib.phtml?uid=11594. Accessed November 12, 2007.

[16] Joseph, T. & Morrison, M. (2006). Nanoforum Report: Nanotechnology in Agriculture and Food. May. http://www.nanoforum.org/dateien/temp/nanotechnology%20in%20agriculture%20and%20food.pdf?08122006200524. Accessed November 11, 2007. 5.

[17] Joseph, T. & Morrison, M. (2006). Nanoforum Report: Nanotechnology in Agriculture and Food. May. http://www.nanoforum.org/dateien/temp/nanotechnology%20in%20agriculture%20and%20food.pdf?08122006200524. Accessed November 11, 2007. 5.

[18] Kalagher, L. (2002). Alfalfa plants harvest gold nanoparticles. Nanotechweb. August 16. http://nanotechweb.org/cws/article/tech/9690. Accessed November 11, 2007.

[19] New lab tackles tainted groundwater with nanotechnology. (2006). Lab Canada. June 28. http://www.labcanada.com/issues/PrinterFriendly.asp?story_id=&id=57675&RType=&PC=&issue=06282006. Accessed November 29, 2007.

[20] Cosier, S. (2006). Big problems, little solutions. Scienceline. September 22. http://scienceline.org/2006/09/22/env-cosier-nanotech/. Accessed August 7, 2007.

[21] Cosier, S. (2006). Big problems, little solutions. Scienceline. September 22. http://scienceline.org/2006/09/22/env-cosier-nanotech/. Accessed August 7, 2007.

[22] Cosier, S. (2006). Big problems, little solutions. Scienceline. September 22. http://scienceline.org/2006/09/22/env-cosier-nanotech/. Accessed August 7, 2007.

[23] Biocide-free antifouling coatings thanks to nanostructured surfaces. (2005). Nano-Tsunami. August 18. http://www.voyle.net/Nano%20Coatings/Coatings%202005-0011.htm. Accessed October 26, 2007.

[24] Nanotechnology cleans up fouling. (2006). Nanotechweb. November 5. http://nanotechweb.org/cws/article/indepth/31723. Accessed November 11, 2007.

[25] Biocide-free antifouling coatings thanks to nanostructured surfaces. (2005). Nano-Tsunami. August 18. http://www.voyle.net/Nano%20Coatings/Coatings%202005-0011.htm. Accessed October 26, 2007.

[26] National Swimming Pool and Spa Institute. (2002). Altair Nanotechnologies Files Patent on NanoCheck Algae Preventer for Prevention of Algae in Swimming Pools. Business Wire. December 16. http://findarticles.com/p/articles/mi_m0EIN/is_2002_Dec_16/ai_95454540. Accessed November 11, 2007.

[27] Loncto, J., Walker M., and Foster, L. (2007). Nanotechnology in the water industry. Nanotechnology Law & Business. June, 157-159. 159.

[28] NanoCheck Algae Prevention From Altair. (2004). The A to Z of Nanotechnology. March 11. http://www.azonano.com/details.asp?ArticleID=663. Accessed November 11, 2007.