Sunday, June 19, 2011

Expanded Polystyrene Natural Life Magazine article footnotes and issues - very long, maybe worth it

My most recent article in the June issue of Natural Life Magazine is about using expanded polystyrene (EPS) for crafting, the last in my series about reusing what would otherwise be waste plastics for crafting purposes. "STYROFOAM (tm) Brand Foam by Dow" is the proper way of writing out the trademarked term for the most well known and oldest brand of expanded polystyrene foam. The packaging I used in  my project was not the Dow material - unfortunately for me because they pay for published pieces using the craft products. For a description and how it differs from other EPS products, go to the STYROFOAM(tm) Brand Foam website.  

Some NLM readers have expressed concerns.

I thought long and hard about doing EPS (I'm now going to avoid the trademark for most of this post) because it really does contribute to the problem of litter in the environment - much of which ends up in the ocean. There has been much discussion about the safety of EPS food containers, most especially about hot food and reheating in the microwave and leaching of chemicals into food.

Here are a couple of links to that information: 

Food grade packaging & testing guidelines:
FDA Food Ingredients and Packaging page
Here are some useful pages on identifying and safely using microwaves and plastics:
Harvard Medical School

Personally, I don't really trust my rather old microwave and whatever internal thermostat it uses, so I avoid the question by not microwaving EPS containers regardless of the label. I can't be certain the temperatures are staying in the designated safe zone to avoid melting, there has been an odd taste sometimes in the dim and distant past, and I have pyrex dishes at home that are better. I never think the EPS cups look clean when I see them out and about. I'm not thinking the grubbiness is necessarily toxic chemical dust, just ordinary-dirt-from-a-warehouse dust, or sitting-in-a-cardboard-box-for-a-while dust. Blech. I have a metal travel mug I tend to carry around with me.

There may be some confusion about off/outgassing of EPS at normal temperatures. According to the MSDS that I have found, the outgassing is very minimal and the products like foam coolers or craft balls are safe when used properly by the consumer. By properly I mean don't burn, melt or dip the stuff into solvents.

Sometimes the confusion arises because the word "foam" is used for more than one kind of product from more than one source chemical. Polyethylene foam can outgas small amounts of odorless flammable hydrocarbons. It should not be stored in confined spaces where a spark might occur. I remember when there were a lot of warnings around to do with foam insulations and mattresses. These are often made of Polyurethane foam, another highly flammable foam that gives off an assortment of nasty gases when heated or burnt, and can create irritating dust.

Here is a very nice article talking about safe use of a number of arts and crafts materials, based around their use in model railroading by adults. It quotes several MSDS sheets with links, and is a rather nice summary. Scroll down for the section about foams.

The blowing agent used for expanding polystyrene is usually a hydrochlorofluorocarbon, although that is changing.  If there is any outgassing, this is what is outgassing, not the styrene - not toxic but not good for the ozone. Remember when we all stopped using hair sprays in the early 1980's to protect the ozone? (Am I showing my age?)

However, this brings me to the very recently released National Toxicology Program 12th Report on Carcinogens.

Styrene, one of the main original components of polystyrene, has newly been classified as "Reasonably anticipated to be a human carcinogen". This falls short of the most damning designation "Known Human Carcinogen". That list is also really worth reading! (Scroll down and click "Access Report Contents".)

To be honest, I tend to assume that all industrial chemicals could be "reasonably anticipated" to be a human carcinogen, especially at high levels of exposure. (Some people are affected by even slight exposures if they have Multiple Chemical Sensitivities. I doubt these folks are doing much crafting with even innocuous non-toxic paints and glues, or natural products like botanical dyes or essential oils.) EPS itself is pretty much inert unless you start burning or melting it with high heat or chemicals, or grinding it into dust.

The commercial foam cutting tools that rely on heat are supposed to melt it well below the thresh-hold heat for burning the foam. Please do your own research on those. I don't own one, but I've seen the little puff of dark smoke when the hot wire first touches the foam and I'm just not sure - so I cut with a serrated edged knife instead IF needed. However maybe I'm being paranoid. Here's an MSDS from Dow, referring specifically to the STYROFOAM (tm) Brand Foam as used in home insulation:

"Upon burning the product generates dense black smoke with small amounts of hydrogen bromide, -chloride, and -fluoride. Studies have shown that the products of combustion of this foam are not more acutely toxic than the products of combustion of common building materials such as wood."

Right, because wood smoke is so good for you. Don't stand downwind of a house on fire. But back to the issue at hand.

I have read the entire section of the report dealing with Styrene, and I am slowly making my way through the other information because it is fascinating. Also included are letters and input disputing the findings in the report. I encourage you to read the report yourselves, rather than rely on simplistic interpretations in the media alone, some of which have excessively alarmist headlines or are too dismissive. Some of the articles also conflate one chemical with another just because the study results are included in the same report. The studies themselves are not connected. (But still worth reading about.)

Here are my conclusions:

Short version:

Factory workers in styrene manufacture and related industries (in Europe and US especially) are exposed to very high concentrations of styrene, orders of magnitude greater than the general population, and are at  statistically relevant higher risk for certain cancers. Styrene is used in many, many products some of which are more noxious than others. These are slowly becoming ubiquitous.

The greatest exposure to styrene in the non-occupational (ie not manufacturer/factory workers) population is from cigarette smoke which is greater than the exposure from all other sources combined.

I think the strongest, immediate conclusion we can draw from this report is that the factories need much more stringent health and safety regulations to protect workers!

Long version:

Here's some of what I talked over with Wendy, the editor of NLM.

Quoting the report:

"The limited evidence for the carcinogenicity of styrene in humans is based on studies of workers exposed to styrene that showed (1) increased mortality from or incidence of cancer of the lymphohematopoietic system and (2) increased levels of DNA adducts and genetic damage in lymphocytes from exposed workers. Elevated risks of lymphohematopoietic cancer were found among workers with higher exposure to styrene after an appropriate elapsed time since first exposure. In some studies, the risks increased with increasing measures of exposure, such as average exposure, cumulative exposure, or number of years since first exposure."

To paraphrase the first part: High occupational levels of exposure to volatile styrene and some styrene compounds and oxides have been found to increase the risk of some cancers and depress immunity in industry workers with the highest spikes in exposure. The mice given the high levels got tumors. The ones given the low levels did not. 

Here are some paragraphs from it that I think are important to put perspective to the issue in relation to crafting with the EPS:

"Polystyrene is used extensively in the manufacture of plastic packaging, thermal insulation in building construction and refrigeration equipment, and disposable cups and containers. Styrene polymers and copolymers are also increasingly used to produce various housewares, food containers, toys, electrical devices, automobile body parts, corrosion-resistant tanks and pipes, various construction items, carpet backings, house paints, computer printer cartridges, insulation products, wood-floor waxes and polishes, adhesives, putties, personal-care products, and other items, and they are used in paper processing (IARC 2002, Luderer et al. 2005, NLM 2008). Styrene-butadiene rubber is the most widely used synthetic rubber in the world (ICIS 2008). Over 70% of styrene-butadiene rubber is consumed in the manufacture of tires and tire products; however, non-tire uses are growing, with applications including conveyor belts, gaskets, hoses, floor tiles, footwear, and adhesives. Another major use of styrene is as a cross-linking agent in polyester resins used in gel-coating and laminating operations in the production of glass-fiber-reinforced plastic products such as boats, bathtubs, shower stalls, tanks, and drums (Miller et al. 1994, EPA 1997). The resins generally contain between 30% and 50% styrene by weight."

So this suggests that the incidence of styrene in the environment is likely to be higher anywhere that there are cars, paper, refrigerators, computers, and new bathrooms. Other places to avoid include nuclear power plants, copy centers and toll booths.

Expanded polystyrene is vaguely analogous to cotton candy (fairy floss) or perhaps honeycomb candy where a tiny amount of liquid sugar (about a teaspoon on a typical stick) is expanded with gas (squirted into the air in cotton candy, carbon dioxide from bicarbonate of soda with honeycomb) to create a lightweight yet voluminous material with many holes and air spaces. The actual amount of styrene in EPS is going to be very much smaller than in products made with these other denser resins and faux rubbers.

Second quote:

"Exposure to styrene can occur in both occupational and non-occupational settings. However, workers in certain occupations potentially are exposed to much higher levels of styrene than the general population. The greatest source of exposure for the general population is cigarette smoking, and daily styrene intake by the nonsmoking population is expected to be orders of magnitude lower than daily intakes for workers in occupations with high styrene exposure levels (Cohen et al. 2002, IARC 2002)."

Cigarette smokers are also ingesting orders of magnitude more benzene than the non-smoking population. An order of magnitude is multiplying or dividing by ten. Two orders of magnitude is by 100, three orders by 1000. The ordinary intake of styrene in the non-smoking general population is hundreds or thousands times LESS than the exposure that appears linked to a higher cancer risk for industry workers. I wonder how many of the factory workers also smoke, and how that might have been corrected for or factored in to the conclusions.

Elsewhere in the report:

"While this study demonstrated that inhalation of both indoor and outdoor air and ingestion of food are important sources of exposure for nonsmokers, it also estimated that exposure from smoking cigarettes was roughly 10 times that from all other routes (indoor and outdoor air, drinking water, soil, and food) combined. Other studies estimated that styrene exposure of smokers was six times that of nonsmokers (Cohen et al. 2002) and that up to 15% of nonsmokers’ styrene exposure could be attributed to environmental tobacco smoke (Miller et al. 1998)."


"Styrene has been detected in a wide range of foods and beverages, with the highest measured levels occurring in unprocessed, raw cinnamon, possibly resulting from the natural degradation of cinnamic
acid derivatives (IARC 1994)."

So watch out for raw cinnamon. It makes my tongue itch.

I guess, bottom line for me, of all the sources of styrene in my environment, EPS packaging at room temperature is most inert, most benign and of least concern when used as a crafting material. If it smells unpleasant, I don't use it for crafting.

Here are my recommendations:

I would discourage all people, especially pregnant women, from using EPS cups and food containers especially for hot foods. Their usage by everyone concerned about the environment should be limited for more reasons than the information in this report, including the problems of plastic waste and the waste of
energy and resources inherent in single use disposable products.

Pregnant women, and anyone with respiratory issues, should be extra cautious about breathing EPS dust (and other dusts too). The residue of sawing with a knife is messy but the particles from this kind of crafting look generally relatively big, rather than dust.  They cling rather than float, and appear much larger than wood dust (a Known Human Carcinogen for "cancers of the nasal cavity" according to the same report) from sanding wood for example, which can look like a cloud if you have ever been in a woodshop.

I keep a lint roller on my table, as well as a carpet sweeper to collect any bits. The particles get statically charged and can be collected with something like an inflated balloon too. In the interests of full disclosure, the totem I made didn't get sawn at all. It was one long piece for the body, and another oddly shaped found part for the head, glued together. There is neither dust nor bits made when you cut thin EPS sheeting with scissors or craft knife for stamp shapes.

If a dust mask makes you feel better, then do use one. If you plan on sanding the EPS, which will make dust, certainly use a dust mask.

For everyone ordinary caution should be used to avoid ingesting this or any non-food craft material:

* Don't do any crafting around food or drinks or have snacks at your work table
* Keep your crafting tools and food prep tools separate
* Wash your hands thoroughly before eating, and take off your apron or grubby craft clothes
* Have adequate ventilation and sufficient light, but avoid drafts 
* Be extra careful of hot tools, including where you set them down
* DO NOT use volatile chemicals on EPS, especially 
spray paints unless they are specially formulated for it. 

* It should go without saying, do not smoke while crafting (or around your kids or if you are pregnant). 
* Don't burn EPS!

If you are still concerned and don't want to craft with expanded polystyrene, then by all means don't. You can make similar totem dolls to the one in the article using small cardboard boxes or wood blocks stacked together and glued, before decoupaging your fabrics and papers. I will continue crafting occasionally with EPS, because it is useful for some jobs.

But I'm also going to continue purchasing my food in containers other than plastic foam as much as I can, and continue striving to decrease the amount of plastic trash in my life. 

Here is a free MSDS search engine.

1 comment:

Unknown said...

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