Volatile Organic Compounds (VOCs)

17 03 2010

What are Volatile Organic Compounds (VOC’s) that we hear so much about?

Simply, they are chemicals which are carbon-based (hence the “organic” in the name, as organic chemistry is the study of carbon containing compounds) and which volatilize – or rather, evaporate or vaporize – at ordinary (atmospheric) temperatures.  This is a very broad set of chemicals!

These volatile organic compounds (VOC’s) are ubiquitous in the environment.  You can’t see them, but they’re all around us.  They’re not  listed as ingredients on the products you bring home, but they’re often there.   The most common VOC is methane, which comes from wetlands and rice agriculture to …well, “ruminant gases” (or cow farts – which are actually not a trivial consideration:  cows are responsible for 18% of all greenhouse gasses – read more here).  We ourselves contribute to CO2 emissions each time we breathe out.  They’re also in paint, carpets, furnishings, fabrics and cleaning agents.

The evaporating chemicals from many products contribute to poor indoor air quality, which the U.S. Environmental Protection Agency estimates is two to five times worse than air outside – but concentrations of VOC’s can be as much as 1,000 times greater indoors than out.  These chemicals can cause chronic and acute health effects, while others are known carcinogens.   Hurricane Katrina proved a lesson in what happens when we don’t pay attention to indoor air quality:  The trailers which were provided to refugees of Katrina proved, in a test done by the Centers for Disease Control and Prevention, to have formaldehyde levels that were 5 times higher than normal; with some levels as high as 40 times higher.  Other airborne contaminants were found to be present.  The result? This is from Newsweek, November 22, 2008:

”  …the children of Katrina who stayed longest in ramshackle government trailer parks in Baton Rouge are “the sickest I have ever seen in the U.S.,” says Irwin Redlener, president of the Children’s Health Fund and a professor at Columbia University’s Mailman School of Public Health. According to a new report by CHF and Mailman focusing on 261 displaced children, the well-being of the poorest Katrina kids has “declined to an alarming level” since the hurricane. Forty-one percent are anemic—twice the rate found in children in New York City homeless shelters, and more than twice the CDC’s record rate for high-risk minorities. More than half the kids have mental-health problems. And 42 percent have respiratory infections and disorders that may be linked to formaldehyde…”

There is no clear and widely supported definition of a VOC.   Definitions vary depending on the particular context and the locale.  In the U.S., the EPA defines a VOC as any compound of carbon (excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates  and ammonium carbonate)  which reacts with sunlight to create smog  –   but also includes a list of dozens of exceptions for compounds “determined to have negligible photochemical reactivity.” 

Under European law, the definition of a VOC is based on evaporation into the atmosphere, rather than reactivity, and the British coatings industry has adopted a labeling scheme for all decorative coatings to inform customers about the levels of organic solvents and other volatile materials present. Split into five levels, or “bands”, these span minimal, low, medium, high, and very high.

These differences in definition have led to a lot of confusion.  Especially in the green building community, we think of VOCs as contributors to indoor air quality (IAQ) problems—and the amount of VOCs is often our only IAQ metric for a product. But there are lots of compounds that meet a chemist’s definition of VOC   but are not photoreactive (as in the EPA definition)  so are not defined as VOCs by regulators. Some of these chemicals—including formaldehyde, methyl chloride, and many other chlorinated organic compounds—have serious health and ecological impacts.  Manufacturers can advertise their products as being “low-VOC” – while containing extremely toxic  volatilizing chemicals, such as perchloroethane in paint, which is not listed as a VOC by the EPA and therefore not required to be listed!

The Canadian government  (bless em) has an extensive list of which chemicals are considered VOC’s and you can access it here.  When products are identified as to which might contain VOC’s, furnishings are often cited and formaldehyde is the chemical highlighted, because it’s the chemical used most widely in fabric finishes.  However, there are many other chemicals on the list which are used in textile production, such as benzenes and benzidines;  methylene chloride, tetrachloroethylene, toluene and pentachlorophenol.

Some manufacturers advertise the amount or type of VOC in their products – and that may or may not be a good indication of what is actually released into the air, because sometimes these chemicals morph into something new as they volatilize.  The key word to remember is: reactive chemistry.  The chemicals don’t exist in a vacuum – heat, light, oxygen and other chemicals all have an effect on the chemical.

VOC’s are also found in our drinking water – the EPA estimates that VOC’s are present in 1/5 of the nation’s water supplies.  They enter the ground water from a variety of sources  – from textile effluents to oil spills.  The EPA lists VOC’s currently regulated in public water supplies (see that list here); they have established a maximum contaminant level (MCL) for each chemical listed.  But little is known about the additive effects of these chemicals.

Another point to remember is that the evaporation doesn’t happen in a pouf!  Chemicals evaporate over time – sometimes over quite long periods of time.  The graph below is of various evaporating chemicals at ground zero (GZ)  of the World Trade Center after the September 11 attacks:

For indoor air quality purposes we should look to results from chamber testing protocols that analyze key VOC’s individually.  Most of these protocols – such as California’s Section 01350, GreenGuard for Children and Schools, Indoor Advantage Gold and Green Label Plus – reference California’s list of chemicals for which acceptable exposure limits have been established.  But even this is not a comprehensive list.

Indoor air quality is certainly important, but in the case of fabrics there are many chemicals used in production which do not volatilize and which are certainly not beneficial to human health!  These include the heavy metals used in dyestuffs and many of the polymers (such as PVC).  So VOC considerations are just one part of the puzzle in evaluating a safe fabric.

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6 responses

6 05 2010
Andrew Oxenford

Why do you have to record VOC content on MSDS when the VOCs are benign: do not Hazardous Air Pollutants (HAPs), Persistent Air Pollutants (POPs) and do not impact on CODs or BODs?
Current legislation does not seem to differentiate between benign VOCs and those that contain highly volatile components that aggregate to the same VOC content.

7 05 2010
oecotextiles

Hi Andrew: I wish I could decipher the workings of the government – and I agree that not all evaporating chemicals are toxic! For example, CO2 is the most prevalent greenhouse gas – yet we all breathe it out with each breath. And then there are the naturally occurring chemicals, such as formaldehyde in an organic apple. I think that perhaps a reason might be related to that old saw, the “dose makes the poison” – in other words, sodium hydroxide, common table salt, is the most commonly used chemical in textile processing. Table salt is not considered a problem – unless a mill is dumping it in great quantities into our streams, where high concentrations kill invertebrates and plants. Also MSDS sheets are designed specifically for workers who may be handling these chemicals each day – they’re exposed to concentrations much higher than what we’d be exposed to from one product. But maybe somebody else has some insight?

19 05 2010
Tara

Hi – I am new to this blog and am just starting to get a better understanding of the wide array of chemicals we are exposed to, through everyday, familiar things. I did have a question that I’m hoping you can help with, and I apologize in advance if it’s a very “beginner-level” question. My question is “In a regular fabric store, are all fabrics treated with flame retardants & other chemicals regardless of the type of fabric? Does washing them prior to use get rid of or reduce these chemicals?”

19 05 2010
oecotextiles

Hi Tara: Your question is not beginner level – most people have no idea. In answer to your question – not all fabrics are treated with flame retardants (in fact, probably none of the fabrics in a store would have these flame retardants) but the fabrics are filled with lots of other chemicals. The weaving, dyeing and finishing of the fabrics requires lots of chemicals. In fact, it is documented that the finished fabrics are, by weight, at least 10% synthetic chemicals which remain in the fabric. Washing them prior to use may get rid of some of the chemicals but I do know that it won’t affect many of them: think of the dyes used for example. The dye chemicals are designed NOT to wash out or rub off – and the dyestuffs routinely contain some of the worst chemicals, like lead, mercury and cadmium. Any functional finishes – such as anti wrinkle, anti stain…or any of the “anti’s”…are also made of highly toxic chemicals which are designed to be persistent. I mean, you’d be upset if your anti wrinkle finish washed out, or if your clothes faded in the wash, right? And phthalates are used in textile printing inks. The list, unfortunately, goes on.

22 05 2010
Tara

Thanks for your response! That is eye-opening. I recently had a baby (now 6 months old) so I’ve started to educate myself on all these issues. I came across a phrase somewhere about chemicals taking on the “harmless aspect of the familiar’ and that is so true in this case…..fabrics are so much a part of our everyday life that it requires a big shift in thinking to even accept that they can be constituted with things that are possibly harmful. I recently found that children’s sleepwear above 9 months of age has to be flame retardant….so all their pajamas are either treated with these toxic chemicals or they are made of synthetic, less flammable materials. So I’m searching now for healthier alternatives. I may end up making some myself with fabric from the store. In general though, is it all finished home furnishings (mattresses, curtains, sheets, quilts, duvets, pillows etc)…that are treated with flame retardants?

23 05 2010
oecotextiles

I love that phrase about chemicals being accepted as part of our everyday lives because they take on the “harmless aspect of the familiar”! That is so true – we also tend to accept all these chemicals as benign until they are uncontrovertibly proven to be otherwise. Lead is a perfect example. Prior to 1971, the Surgeon General of the U.S. mandated that lead was safe up to 60 micrograms per deciliter of blood; that was slowly reduced to 10 micrograms per deciliter of blood. But now we know that ANY detectable lead levels affect neurological development, yet the U.S. threshold remains at 10. You can read about lead in textiles in our blog post http://oecotextiles.wordpress.com/2009/12/01/cpsia-lead-and-textiles-in-your-life/.
Flame retardants are not generally mandated for use in private homes – only for public spaces – except in certain products, like children’s sleepwear and mattresses; some furniture has flame retardants – as well as lots of other products, even those you wouldn’t normally think of as having them, like computers and electrical products. The history of the requirements for children’s sleepwear is interesting – the CPSIA banned Tris from children’s sleepwear because it was found to cause cancer in laboratory animals. Also some manufacturers might claim that their product (like a couch) is PBDE free, but it might contain decaBDE or penta BDE, which scientists are finding are just as bad for us and our environment as their cousin, PBDE. The Environmental Working Group reports that PBDE’s are not used in children’s sleepwear.

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