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Green Building Discussion
Topic: Formaldehyde Problems and Solutions
Discussion Patricipants:
- The Satterlees ask about Formaldehyde trade-offs
- Eric Hart asks some more
- Nadav Malin responds
- Alex Wilson on the production process
- Tony Novelli wonders about OSB on the job
- Sigi Koko on chemical constituents
- Jim Newman on splinters
- Sigi Koko on splinters
- Tony Novelli on field experience
- Norbert Senf on embodied energy
All postings are the opinion of the writer, and BuildingGreen can take no responsibility for their accuracy or appropriateness.
The Satterlees ask about Formaldehyde trade-offs
From: The Satterlees
Sent: Friday, September 27, 1996 5:52 PM
A while back someone asked me about the tradeoff between the hazards of formaldehyde to the comsumer vs. the hazards of working with methyl diisocynate to the workers. Any reactions / comments?
Amos Satterlee
Eric Hart asks some more
From: Eric D. Hart
Sent: Saturday, September 28, 1996 10:45 PM
Hello: We built a strawbale cabin with I-beams that use OSB between microlams or clear pine. Does anybody know if there is a good article (or bibliography) that will run down what kind of not so friendly chemicals and resins are used in the production of engineered wood (and what their human and environmental impacts are) and what the embodied energy of such products are? Have heard bad things about a Truss Joist plant in Northern Minnesota so want to know what all the issues are before making a judgement. Using I-beams turned out to be an easy way to do the trusses and window boxes for this structure. Before we adopt I-beams as a standard building component, I'm checking out the 'environmental correctness' of I-beams. Thanks for your help.
Eric D. Hart Community Eco-design Network Minneapolis, MN USA (612) 305-2899 erichart@mtn.org http://www.umn.edu/nlhome/m037/kurtdand/cen
Nadav Malin responds
From: Nadav Malin
Sent: Sunday, September 29, 1996 4:48 AM
EBN's article on sheathing products went into many of these issues, but it's quite dated now (came out in 92). Most OSB is made using Phenol formaldehyde, but some is made with MDI (methyl diisocyate), which is chemically related to polyurethane. I believe the OSB made by L-P, which was heavily advertised as being "formaldehyde-free" a couple of years ago, is made with MDI.
The Truss-Joist MacMillan plant in Northern Minnesota is where they first produced Timberstrand, a thick engineered wood product now being sold for wall studs, short headers, and other uses. They now have a second plant in Kentucky. They did have some incidents of workers getting sick when they began operations. Apparently, forming machines are well isolated, but some material was being moved into storage before all the binder had completely cured, so workers were exposed to uncured MDI resin. As no one had tried making OSB so thick before, they didn't know that the cores might take a long time to cure.
On the differences between MDI and Phenol formaldehyde, by rudimentary understanding is that there is a relationship between how reactive (and hazardous) the uncured binder is, and how stable the end product is. MDI is very reactive, but once cured it's very safe. PF is less reactive, so it's less hazardous to the worker in the factory, but some formaldehyde does continue to offgas after manufacture.
In addition to embodied energy, I would suggest looking into the potential and actual releases to the environment of toxic intermediaries from the manufacture of these binders. Data on actual releases is hard to find, but a careful of search of US government Toxic Release Inventory data might yield something.
Nadav
Alex Wilson on the production process
From: Alex Wilson
Sent: Saturday, September 28, 1996 5:14 AM
This is indeed an important question. We often hear that the formaldehyde-based binders (urea-formaldehyde (UF), primarily, but also phenol-formaldehyde (PF)) are worse from the standpoint of the end-user, while methyl diisocyanate (MDI) binders are worse for factory workers. I understand that factories producing wood products made with MDI have to have state-of-the-art pollution-control and safety equipment to contain wayward MDI. If the control equipment on MDI plants indeed captures most or all of these wayward compounds, then I suspect that there is little real difference in safety between these plants and those producing UF- or PF-binder wood products. Because the MDI-binder plants tend to be newer, in fact, I suspect the pollution-control equipment is usually better than that in older plants using UF or PF. I've been in plants where the sweet smell of formaldehyde is pervasive--and formaldehyde is a suspected human carcinogen?
Anyone else have thoughts on this issue? I'd be interested in specific data if anyone has it.
Alex Wilson Environmental Building News
Top of file
Tony Novelli wonders about OSB on the job
From: ANovelli@aol.com
Sent: Saturday, September 28, 1996 12:23 PM
Alex,
I would assume that the chemicals you are talking about are used in oriented strand board (OSB)? If so, one friend of mine who's a framer said that slivers from this material would cause the area to become red and swollen almost immediately. He may have developed a sensitivity due to long-term/repeated exposures though.
I have the impression that OSB is a more efficient use of the timber, though it would seem like other binding agents could be used, especially with what seems to be a pervasive sensitivity to these chemicals. Don't we house to protect ourselves from the elements? Best,
Tony Novelli
Sigi Koko on chemical constituents
From: Sigi Koko/WDC
Sent: Monday, September 30, 1996 9:59 AM
In response to " . . . the tradeoff between the hazards of formaldehyde to the comsumer vs. the hazards of working with methyl diisocynate to the workers. Any reactions / comments?":
¦ formaldehyde monomer (unreacted formaldehyde molecule) is a known carcinogen, with a NIOSH exposure ceiling limit at 5 ppm. It is toxic even at very low exposure levels. ¦ urea formaldehyde and phenol resorcinol formaldehyde are the most commonly used because they are the least expensive to produce; they also do not fully cure, so formaldehyde is emitted over very long periods of time. ¦ phenolic resin and melamine resin (both formulated with formaldehyde) are more expensive to produce, but are inert (not emitting formaldehyde) as fully cured polymers. They are still hazardous when "wet" (not cured). ¦ isocyanates, or isocyanurates, contain cyanide, which is a deadly gas when emitted; cyanide gas is created when these compounds are exposed to extreme heat or fire. MDI has a NIOSH exposure ceiling limit of .02 ppm. ¦ ALL of these compounds pose a threat to workers and to the environment during production of the resins. (No matter how state-of-the-art a manufacturer's environmental control equipment is, there is always the risk of chemical pollution.)
Also to confirm the comment: "one friend of mine who's a framer said that slivers from this material would cause the area to become red and swollen almost immediately": I used to frame houses also, and splinters (even small ones) from OSB, as well as microlams, are notorious for causing immediate irritation, infection, and slow healing. I don't think it's a developed sensitivity.
Jim Newman on splinters
From: Jim Newman
Sent: Monday, September 30, 1996 1:05 PM
Interesting points, but I'm not so sure about the splinter theory. Different woods have different abilities to cause irritation as splinters. Seemingly more ability than glues. Redwood, cedar, mahogany...and lots of others can be pretty mean on your hands. I have a feeling that the anecdotal evidence here is fed by the percieved "un-naturality" of the products.
Jim Newman, Construction Forum, Inc. jnewman@user1.channel1.com
Sigi Koko on splinters
From: Sigi Koko/WDC
Sent: Monday, September 30, 1996 1:35 PM
I agree with your redwood, cedar, mahogany, etc, list of woods; but those are also woods that contain natural resins that are known to irritate skin as well as the respiratory system. (If I'm not mistaken, these resins are also what gives these woods their resistance to bugs and other pests.) And I don't find composite woods to be particularly bad; they are a great way to utilize scrap wood from the lumber industry, as well as utilizing alternative agricultural products such as straw . . . I just think that it would behoove the building industry to develop and promote alternative resin binders that are not quite as offensive to the ones that are currently utilized. Thanks for your comment. Sigi Koko HOK, Sustainable Design Group, DC
Tony Novelli on field experience
From: ANovelli@aol.com
Sent: Tuesday, October 01, 1996 10:25 AM
Doubtful the case. My friend has had little interst in "green" technologies, and has been a lead framer for a dozen years or so, well before the arrival of OSB. It was interesting to me that when our discussions turned to more green topics, he had been complaining about how much *more* irritating it was than the traditional stick frame materials. And as you might suspect, he's one of these animalistic framers who works like the devil. To get him complaining is a tough one. He especially hated the fact that he had to wear a mask when cutting OSB, something he never had to do before with plywood.
Certianly different woods can be very harmful, some much worse than the ones you quoted. But my friend has almost never worked with them in any quantity, so I think the glues and resins are clearly suspect here.
Norbert Senf on embodied energy
From: Norbert Senf
Sent: Monday, September 30, 1996 10:29 AM
> Eric Hart asked after emodied energy info.
For a detailed embodied energy analysis of a structual timber, a roof truss, and cladding boards done by the Finnish Building Research Institute, see:
http://mha-net.org/docs/sustain.htm -- -------------------------------------------------------- Norbert Senf mheat@hookup.net Masonry Stove Builders Shawville, Quebec http://mha-net.org/msb
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