GMOs and nanotechnology – hope for the future

6 06 2013

I ran into some interesting ideas that seem to display why we should not immediately discredit new science – like genetic engineering or nanotechnology – because it might well provide clues to how we can continue to live on this planet.  So rather than taking a global stand against GMOs or nanotechnology perhaps we should look at how the science is used.

Carbon dioxide (CO2)  – the natural gas that allows sunlight to reach the Earth –  also prevents some of the sun’s heat from radiating back into space, thus trapping heat and warming the planet. Scientists call this warming the greenhouse effect. When t­his effect occurs naturally, it warms the Earth enough to sustain life. In fact, if we had no greenhouse effect, our planet would be an average temperature of minus 22 degrees Fahrenheit (minus 30 degrees Celsius)[1].  My kids would love the skiing, but they’d be too dead to enjoy it.  So carbon dioxide and the greenhouse effect are necessary for Earth to survive. But human inventions like power plants and cars, which burn fossil fuels, release extra CO2 into the air. Because we’ve added (and continue to add) this carbon dioxide to the atmosphere, more heat is stored on Earth, which causes the temperature of the planet to slowly rise, a phenomenon called global warming.

Carbon dioxide isn’t the only greenhouse gas (GHG) – others include water vapor, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride – but it’s the most important.  And it’s going up as a direct result of human activity.[2]  Just recently, we passed a milestone that climate scientists have warned is impressively scary – for the first time in human history, atmospheric carbon dioxide levels will surpass 400 ppm.[3]

So what to do? Traditionally, we’ve relied on natural systems to deal with this extra CO2 – like trees and other plants which soak up the stuff through photosynthesis.  But the amounts being generated exceed the capacity of natural systems to deal with it.  So we look to technological solutions, which basically consist of:  capture (i.e., trapping the gas at its emission source and then putting it someplace where it won’t escape) and geologic sequestration or storage (putting it someplace where it won’t escape.)  But I’m not a believer in these measures – after all, captured CO2 must be transported (by rail, truck or ship) to its final storage place.  And where is there a storage place that will not leak and can accommodate the 30 billion metric tons of CO2 we generate every year – without dire environmental consequences.

We have to look outside the box.  There have been many such ideas, from the more outlandish (i.e., create man-made volcanoes to pump sulfur dioxide into the atmosphere to block sunlight and cool the planet[4]) to several I’ve outlined below that just might help.  But they depend  on the use of GMO and nano science.

As Technology.org describes it:  “It is not widely appreciated that the most substantial process of carbon sequestration on the planet is accomplished by myriad marine organisms making their exoskeletons, or shells.   Shells are produced biologically from calcium and magnesium ions in sea water and carbon dioxide from the air, as it is absorbed by sea water. When the organisms die, their shells disintegrate and form carbonate sediments, such as limestone, which are permanent, safe carbon sinks.”[5]

from ecoco: sustainable design

from ecoco: sustainable design

By studying how sea urchins grow their own shells, scientists at Newcastle University in the UK have discovered a way to trap CO2 in solid calcium carbonate using nickle nanoparticles.  “It is a simple system,” said Dr Lidija Siller from Newcastle University. “You bubble CO2 through the water in which you have nickel nanoparticles and you are trapping much more carbon than you would normally—and then you can easily turn it into calcium carbonate.”[6]  Most carbon capture and storage programs must first trap the CO2 and then pump it into holes deep under ground, which is both expensive and has a high environmental risk.    Lead author, PhD student Gaurav Bhaduri, is quoted: “ [the nickel catalyst]  is very cheap, a thousand times cheaper than carbon anhydrase”.  The two researchers have patented the process and are looking for investors.

Meanwhile, MIT professor Angela Belcher, who had done her thesis on the abalone,   and graduate students Roberto Barbero and Elizabeth Wood are also looking into this.  They have  created a process that can convert carbon dioxide into carbonates that could be used as building materials. Their process, which has been tested in the lab, can produce about two pounds of carbonate for every pound of carbon dioxide captured.

Their process requires using genetically modified yeast.

Yeast don’t normally do any of those reactions on their own, so Belcher and her students had to engineer them to express genes found in organisms such as the abalone. Those genes code for enzymes and other proteins that help move carbon dioxide through the mineralization process.

The MIT team’s biological system captures carbon dioxide at a higher rate than other systems being investigated. Another advantage of the biological system is that it requires no heating or cooling, and no toxic chemicals.

Dr. Belcher has also used genetically modified viruses so they would have a binding affinity with carbon nanotubes – which allowed them to build a high-powered lithium ion battery cathode that could power a green LED.  Dr. Belcher thinks that she might one day drive a virus-powered car.

I think these two examples demonstrate that we should always keep an open mind.  And remember that it’s not always the science that’s causing a problem, but rather how we use it.  The idea that GMO seeds are intellectual property (owned largely by Monsanto) for example, is one of the wrong ways to use this technology.  But let’s not throw the baby out with the bath water.

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Nylon 6 and Nylon 6,6

5 06 2012

Nylon is a synthetic polymer called a polyamide  because of the characteristic monomers of amides in the backbone chain.  Polyamides are also naturally occurring – proteins such as wool and silk are also polyamides.

We commonly see two basic types of nylon used in fabrics: nylon 6 and nylon 6,6:

  • Nylon 6,6:  Two different molecules (adipic acid and hexamethylene diamine)  are combined to create repeat units of 6 carbon atoms, thus the name nylon 6,6.
  • Nylon 6:  Only one type of molecule is used in the formation of nylon 6, which also has 6 carbon atoms.  The repeat unit for type 6 nylon is made from caprolactam (also called ε-caprolactam).

Remember polyester is also a polymer (as are lots of naturally occurring things).  And like polyester, the nylon polymers are theoretically unreactive and not particularly harmful, but that’s not true of the monomers:

  • A small % of the monomers escape during production (off gassing or into water), which have environmental consequences.
  • With production expected to be over  4.4 million pounds/year by 2020, burden on water treatment facilities is immense.
  • Monomers are precipitated out during treatment, so they are present in the sludge.

The manufacture of both nylon 6,6 and nylon 6 uses cyclohexane as a precursor [1] – and cyclohexane is made from benzene, “one of the most challenging processes in the chemical industry”.[2]  Benzene is listed as a human carcinogen by the US Department of Health and Human Services.  It is associated with acute myeloid leukemia (AML), aplastic anemia, myleodysplastic syndrome (MDS), acute lymphoblastic leukemia (ALL), and chronic myeloid leukemia (CML)[3]  The American Petroleum Institute (API) stated in 1948 that “it is generally considered that the only absolutely safe concentration for benzene is zero.” [[4]

But the real culprits are the generation of unwanted by-products of nylon manufacture:  ammonium sulfate [5] in the case of nylon 6 and nitrous oxide in the case of nylon 6,6.

For nylon 6, the conventional synthesis route to caprolactam uses toxic hydroxylamine (NH2OH) and, in the last two steps, concentrated sulfuric acid. Every metric ton of caprolactam produces up to 4.5 tons of ammonium sulfate as a by-product [6].  As with many chemicals now in use, there is no data to evaluate ammonium sulfate as to toxicity to humans, though it has been shown to affect development, growth and mortality in amphibians, crustaceans, fish, insects, mollusks, and other organisms.[7]

In addition, waste water generated during production of nylon-6 contains the unreacted monomer, caprolactam. Owing to the polluting and toxic nature of ε-caprolactam, “its removal from waste streams is necessary”[8]

In evaluating the chief components of nylon 6,6  (hexamethlylenediamine and adipic acid), we find a darker situation.   Hexamethlylenediamine is a  petroleum derivative,  with the usual consequences of petroleum processing. It is considered “mildly toxic”[9] (though in one study, ten administrations of 700 mg/kg to mice killed 3 of 20[10]).   But the production of the other monomer,  adipic acid,  requires the oxidation of cyclohexanol or cyclohexanone by nitric acid, a process which produces nitrous oxide (N2O) –  a greenhouse gas 300 times more potent than CO2.[11]  A study published in 1991 credits the production of nylon – and the concurrent by-product of nitrous oxide – as contributing as much as 10% to the increased observance of atmospheric N2O.[12]  And this is a great concern, so much so that there is increased talk of our “nitrogen footprint”.

Nitrogen is one of the 5 elements (the others are carbon, hydrogen, oxygen, and phosphorus) that make life possible. It is essential for the creation of DNA, amino acids and proteins. 79% of the earth’s atmosphere is made up of nitrogen, but living things can’t use it in this form called dinitrogen (N2).  So in the nitrogen cycle, lightning  converts N2 into nitrate, which is carried to Earth by rain, where it enters the food chain.  When organisms die, bacteria recycles the nitrogen in them and it returns to the atmosphere.  Pretty elegant, isn’t it?

From: Nitrous Oxide Focus Group

But we have disrupted this nitrogen cycle.  A study by University of Virginia environmental scientist James Galloway and colleagues reported that from 1970 to 2008, world population increased by 78% and reactive nitrogen creation grew 120%.[13] The turning point, according to the International Nitrogen Initiative, came in 1909 when humans figured out how to combine hydrogen with N2 to create ammonia – which was used to produce fertilizer. Humans have introduced additional reactive nitrogen into the environment by expanding the production of soybeans, peanuts and alfalfa, (leguminous) crops which host nitrogen-fixing bacteria that convert N2 into reactive nitrogen. We use ammonia to manufacture nylon, plastics, resins, animal and fish feed supplements, and explosives. Fossil fuel burning industries and vehicles produce nitrogen emissions, and nitrogen is a component of the electronics, steel, drug, missile and refrigerant industries.

A single nitrogen molecule can cascade through the environment affecting air and water quality, human health and global warming in numerous ways(click here for a summary):

  • Runoff from agriculture—from fertilized crops fed to animals, from manure, and from biofuel and crops—enters rivers and streams and can contaminate groundwater. When nitrogen-loaded runoff makes its way to the ocean, it can result in eutrophication, where algae bloom, then die, depleting the oxygen and suffocating plants and animals. Runoff from urban areas, sewage treatment plants, and industrial wastewater also contribute to eutrophication.
  • Nitrogen is also a component of acid rain, which can acidify soils, lakes and streams. While some trees may utilize the extra nitrogen to grow, others experience foliage damage and have reduced tolerance for stress.
  • Our air quality is affected by nitrogen emissions from vehicles, fossil fuel burning industries (like coal), and the ammonia from agriculture, which cause ground-level ozone. High concentrations of ozone affect human respiratory and cardiovascular health and disrupt photosynthesis in plants.
  • Climate change is both influenced by and exacerbated by nitrogen. For example, nitrogen may stimulate plant growth, resulting in more carbon dioxide uptake in some forests.

Scientists have stressed the need to reduce fossil fuel emissions, improve wastewater treatment, restore natural nitrogen sinks in wetlands, and both reduce the use and increase the efficiency of nitrogen fertilizers. Galloway’s study also underscores the importance of better management of animal waste from the concentrated animal feeding operations that produce most of our meat today.

Another concern of using nylon is that all nylons break down in fire and form hazardous smoke.  Also smoke from burning nylon at a landfill emits the same chemicals,  typically containing  hydrogen cyanide, nitrous oxide (N2O) and dioxins[14].

Because nylon 6,6 is made from two different molecules, it is very difficult to recycle and/or repurpose.  Trying to separate and re-use them is like “trying to unbake a cake”.  However, nylon 6, because it is made from only one molecule, can easily be re-polymerized, and therin lies it’s claims to environmental superiority.  But  nylon production uses a lot of energy – about double that of polyester.  If recycling it uses about half the energy as is needed to produce virgin nylon, then recycled nylon and virgin polyester use about the same amount of energy.

Nylon 6 is becoming the new green darling of designers – but unless the recyling process captures all emissions, treats wastewater and sludge and also recaptures the energy used, the claim is tepid at best.  And nylon, unlike polyester, does degrade,  but slowly[15], giving it plenty of time to release its chemical load into our groundwater

I couldn’t find any data on the toxicity of nylon as fabric, but the government of Canada has evaluated nylon 6,6 because it is also used in cosmetics, and classified it as a “medium human health priority”; it is also on the Environment Canada Domestic Substance List.[16]  Another study found that some of the chemicals in nylon kitchen utensils migrated into food.[17]


[1] The remaining less than five percent of installed caprolactam capacity is via the cyclohexane photonitrozation process of Toray, which goes directly from cyclohexane to the oxime, or the SNIA Viscosa process, which utilizes toluene as feedstock and proceeds via oxidation-hydrogenation-nitrozation.  http://www.chemsystems.com/about/cs/news/items/PERP%200910_1_Caprolactam.cfm

[2] Villaluenga, J.P. Garcia, Tabe-Mohammadi, A., “A review on the separation of benzene/cyclohexane mixtures by pervaporation processes, Journal of Membrane Science, Vol 169, issue 2, pp. 159-174, May 2000.

[3] Smith, Martyn T. (2010). “Advances in understanding benzene health effects and susceptibility”. Ann Rev Pub Health 31: 133–48. DOI:10.1146/annurev.publhealth.012809.103646.

[4] American Petroleum Institute, API Toxicological Review, Benzene, September 1948, Agency for Toxic Substances and Disease Registry, Department of Health and Human Services

[6] Hoelderich, Wolfgang and Dahlhoff, Gerd, “The Greening of Nylon”, Chemical Innovation, February 2001, Vol 31, ppg. 29-40 and Weston, Charles et al, “Ammonium Compounds”, Encyclopedia of Chemical Technology, June 20, 2003, http://onlinelibrary.wiley.com/doi/10.1002/0471238961.0113131523051920.a01.pub2/abstract

[8] Kulkarni, Rahul and Kanekar, Pradnya, “Bioremediation of e-Caprolactum from Nylon 6 waste water…” MICROBIOLOGY, Vol 37, Number 3 1997

[10] “Handbook of Toxic Properties of Monomers and Additives”, Victor O. Sheffel, CRC Press, Inc., 1995

[11] 2007 IPCC Fourth Assessment Report (AR4) by Working Group 1 (WG1), Chapter 2 “Changes in Atmospheric Constituents and in Radiative Forcing” which contains information on global warming potential (GWP) of greenhouse gases

[12] Thiemens, Mark and Trogler, William, “Nylon Production: An unknown source of atmospheric nitrous oxide”, Science, February 1991, vol 251, pp 932-934

[13] Galloway, JN, and Gruber,  “An Earth-system perspective of the global nitrogen cycle.” Nature 451, 2008, 293-296.

[15] For nylon fabric, current estimates are 30 – 40 years.





Organic agriculture and climate change

29 07 2009

global6

The debate over sustainable agriculture has gone beyond the health and environmental benefits that it could bring in place of conventional industrial agriculture. For one thing, conventional industrial agriculture is heavily dependent on oil, which is running out; and it is getting increasingly unproductive as the soil is eroded and depleted. Climate change will force us to adopt sustainable, low input agriculture to ameliorate the worst consequences of conventional agriculture, and to genuinely feed the world.

And climate change is upon us.  I’m sitting in Seattle experiencing an “historic heat wave” while reading that the Hadley Center of the British Meteorological Organization has said the world’s temperature will increase by 8.8 degrees F rather than 5.8 degrees F this century.

The Inter-Governmental Panel on Climate Change (IPCC) has said we can expect a considerable increase in heat waves, storms, floods, and the spread of tropical diseases into temperate areas, impacting  the health of humans, livestock and crops. It also predicts a rise in sea levels up to 35 inches this century, which will affect something like 30% of the world’s agricultural lands (by seawater intrusion into the soils underlying croplands and by temporary as well as permanent flooding). If the Hadley Center is right, the implications will be even more horrifying: Melting of the Antarctic, the Arctic, and especially the Greenland ice-shields is occurring far more rapidly than was predicted by the IPCC. This will reduce the salinity of the oceans, which in turn  weakens (if not diverts) oceanic currents such as the Gulf Stream from their present course . And if that continues, it would eventually freeze up areas that at present have a temperate climate, such as Northern Europe.

According to the Institute of Science in Society, “It is becoming clear that climate change and its different manifestations (as mentioned above) will be the most important constraints on our ability to feed ourselves in the coming decades. We cannot afford to just sit and wait for things to get worse. Instead, we must do everything we can to transform our food production system to help combat global warming and, at the same time, to feed ourselves, in what will almost certainly be far less favorable conditions.”

But before we tackle the question of how best to feed ourselves during these “less favorable” times: how can organic agriculture help with global warming?

It’s generally assumed that various Greenhouse Gases (GHG) are responsible for
global warming and climate change.   On a global scale, according to a study commissioned by IFOAM, agriculture has been responsible for approximately 15% of all GHG emissions:

  • 25% of all CO2 emissions come from agriculture
  • 60% of CH4 (methane) emissions come from agriculture
  • 80% of N2O (nitrous oxide) emissions  come from agriculture

About 60% of the CO2 emissions from human and animal activities is absorbed by the oceans and plants; the remaining 40% builds up in our atmosphere.    So what to do about the 40% that’s building up in our atmosphere?  Where can it be stored?

428

In  looking at ways to “defuse” this CO2 build up, scientists began looking at carbon “sinks”.  Carbon sinks are natural systems that suck up and store carbon dioxide from the atmosphere. The main natural carbon sinks are plants, the ocean and soil. Plants grab carbon dioxide from the atmosphere to use in photosynthesis; some of this carbon is transferred to soil as plants die and decompose. The oceans are a major carbon storage system for carbon dioxide. Marine animals also take up the gas for photosynthesis, while some carbon dioxide simply dissolves in the seawater.

Initially forests were thought to be the most efficient way to sequester (or absorb) this carbon.  It was thought that escalating fossil fuel consumption could be balanced by vast forests breathing in all that CO2.   But  these sinks, critical in the effort to soak up some of our greenhouse gas emissions, may be maxing out, thanks to deforestation, and human-induced weather changes that are causing the oceanic carbon dioxide “sponge” to weaken.

New data is beginning to show that it may be that the soil itself makes more of a difference (in terms of carbon sequestration)  than what’s growing on it.  On a global scale, soils hold more than twice as much carbon as does vegetation (1.74 trillion tons for soil vs. 672 billion tons for vegetation) – and more than twice as much as is contained in our atmosphere.

The Rodale Institute Farming Systems Trial (FST), launched in 1981, is a 12 acre side by side experiment comparing three agricultural management systems: one conventional, one legume-based organic and one manure-based organic.  In 23 years of continuous recordkeeping,  the FST’s two organic systems have shown an increase in soil carbon of 15 – 23%, with virtually no increase in non-organic systems.

carbonsoil

This soil carbon data  shows  that improved global terrestrial stewardship–specifically including regenerative organic agricultural practices–can be the most effective currently available strategy for mitigating CO2 emissions. [2]

But although it is well established that organic farming methods sequester atmospheric carbon, researchers have yet to flesh out the precise mechanisms by which this takes place.   One of the keys seems to be in the handling of organic matter – while conventional agriculture typically depletes organic matter, organic farming builds it thru the use of composed animal manures and cover crops.  In the FST, soil carbon levels increased more in the manure-based organic system than in the legume-based organic system, presumably because of the incorporation of manures, but the study also showed that soil carbon depends on more than just total carbon additions to the system–cropping system diversity or carbon-to-nitrogen ratios of inputs may have an effect. “We believe that the differences in decay rates [of soil organic matter] have a lot to do with it,” says Hepperly, since “soluble nitrogen fertilizer accelerates decomposition” in the conventional system.

The people at Rodale put the carbon sequestration argument into an equivalency we can all understand: think of it in terms of the number of cars that would be taken off the road each year by farmers converting to organic production.  Organic farms sequester as much as 3,670 pounds of carbon per acre-foot each year. A typical passenger car, according to the EPA, emits 10,000 pounds of carbon dioxide a year (traveling an average of 12,500 miles per year). Here’s how many cars farms can take off the road by transitioning to organic:  car

U.S. agriculture as currently practiced emits a total of 1.5 trillion pounds of CO2 annually into the atmosphere. Converting all U.S. cropland to organic would not only wipe out agriculture’s massive emission problem, but by eliminating energy-costly chemical fertilizers, it would actually give us a net increase in soil carbon of 734 billion pounds.

Organic agriculture is an undervalued and underestimated climate change tool that could be one of the most powerful strategies in the fight against global warming, according to Paul Hepperly, Rodale Institute Research Manager.  In addition to emitting fewer GHGs while sequestering carbon, organic agriculture uses less energy for production.  A study done by Dr. David Pimentel of Cornell University found that organic farming systems used just 63% of the energy required by conventional farming systems, largely because of the massive amounts of energy requirements needed to synthesize nitrogen fertilizers.

Taking it one step further beyond the energy inputs we’re looking at, which help to mitigate climate change, organic farming:

  • eliminates the use of synthetic fertilizers, pesticides and genetically modified organisms (GMOs) which is  an improvement in human health and agrobiodiversity
  • conserves water (making the soil more friable so rainwater is absorbed better – lessening irrigation requirements and erosion)
  • ensures sustained biodiversity
  • and compared to forests, agricultural soils may be a more secure sink for atmospheric carbon, since they are not vulnerable to logging and wildfire.

Organic production has a strong social element and includes many Fair Trade and ethical production principles.  As such it can be seen as more than a set of agricultural practices, but also as a tool for social change.[3] For example, one of the original goals of the organic movement was to create specialty products for small farmers who could receive a premium for their products and thus be able to compete with large commercial farms.

And actually, it seems that modern industrial agriculture is on the way out.  The Food and Agriculture Organization of the United Nations (FAO) admitted in 1997 that wheat yields in both Mexico and the USA had shown no increase in 13 years  – blamed on the fact that fertilizers are becoming  less and less effective, as are pesticides.   The farmers are losing the battle.  Conventional agrochemical use (which includes many highly toxic substances) also has many immediate human impacts:  documented cases of short term illnesses, increased medical costs and the build up of pesticides in human and animal food chains.  The chemicals also contaminate the drinking and ground water.  And industrial agriculture is far too vulnerable to shortages in the availability of fuel and to increases in the price of oil.

That’s a lot to think about when looking for your next T shirt, so before you plunk down your money for another really cool shirt,  think about what you  will be getting in exchange.


[1] I should point out that although “sinks” in vegetation and soils  have a high
potential to mitigate increases of CO2 in the atmosphere, they are not
sufficient to compensate for heavy inputs from fossil fuel burning.  The long-term solution to global warming is simple:  reduce our use of fossil fuel, somehow, anyhow!
Yet the contribution from agriculture  could buy time during which
alternatives to fossil fuel can take affect – especially if that agricultural system is organic.

[2] http://www.rodaleinstitute.org/files/Rodale_Research_Paper-07_30_08.pdf

[3] Fletcher, Kate, Sustainable Fashion and Textiles, p. 19





Carbon footprint of the textile industry

25 05 2009

We’re starting a series of blogs on the carbon footprint of textiles.    Because it’s such a complex subject we’re breaking it into smaller portions, beginning with looking at the textile industry as a whole.   In other words, why the fuss over textiles?

Fabrics, believe it or not, have a large carbon footprint.  In other words, it takes a lot of energy to produce fabrics.  According to the U.S. Energy Information Administration, the U.S. textile industry is the 5th largest contributor to CO2 emissioins in the United States (after primary metals, nonmetallic mineral products, petroleum and chemicals).  In the developing world, where the textile industry represents a larger percentage of GDP and mills are often antiquated, the CO2 emissions are greater.

In fact, today’s textile industry is one of the biggest sources of greenhouse gasses on Earth, due to the huge size and scope of the industry as well as the many processes and products that go into the making of textiles and finished textile products. (See Vivek Dev, “Carbon Footprint of Textiles”, April 3, 2009, http://www.domain-b.com/environment/20090403_carbon_footprint.html)

Based on estimated annual global textile production of 60 billion kilogrms (KG) 0f fabric, the estimated energy and water needed to produce that 60 billion KG of fabrics boggles the mind:  1,074 billion KWh of electricity (or 132 million metric tons of coal) and between 6 – 9 trillion liters of water.

Fabrics have been the elephant in the room for too long.  Do we overlook them because they are almost always used as a part of a finished product, such as sheets, blankets, sofas, curtains, and of course clothing?  It’s estimated that clothing and textiles account for about one ton of the 19.8 tons of total CO2 emissions produced by each person in the U.S. in 2006 (see Jurg Rupp, “Ecology and Economy in Textile Finishing”, Textile World, Nov/Dec 2008).

In the U.K., the Carbon Trust, working with Continental Clothing, has developed the world’s first carbon label for clothing (http://www.environmentalleader.com/2009/03/27/uk-launches-first-carbon-footprint-label-for-retail-clothing/)  The new label will provide the carbon footprint of the garment, from raw materials and  manufacture to use and disposal.

carbon footprint label

carbon footprint label

The first point we want you to keep in mind is that the industry is huge, and because of its size it’s impacts are profound.  There is more to think about when buying a fabric than thread counts or abrasion ratings.