This blog post, originally shared in the Pharos Signal, includes information about parts of Pharos that are no longer available. Please use it for historical reference and for the other useful information it contains.
Last month, the Pharos research team released a Healthy Building Network (HBN) report on asthmagens in building materials titled Full Disclosure Required: a Strategy to Prevent Asthma Through Building Product Selection. Since then, Signal readers have raised some great questions about our report and the HBN priority asthmagens filter that we added to the Pharos Project Building Product Library at Greenbuild last November:
Aren’t there other more conventional triggers for asthma than chemicals from building materials?
Public health agencies often report dust, pet dander, environmental air pollution, tobacco smoke, respiratory infections, mold, exercise, and stress as common triggers of asthma attacks. However, it is currently unclear how much of a role these triggers play in the physiological changes that bring about asthma, or whether they simply incite an asthma attack in those who already suffer from the condition. Immunological and epigenetic mechanisms for asthma onset (that is, initiation of the disease, not only its symptoms) have been linked to some of these triggers including dust and tobacco smoke, but other scientific studies have also demonstrated negative results1.
Asthma is a complex disease, and there is not enough evidence to point to any one cause. However, it seems significant that despite better management of asthma through medication and reduced exposure to these commonly cited triggers, the incidence of asthma has continued to rise, especially in children.
Our report goes beyond previous research on common asthma triggers in order to better highlight research on other potential sources of asthma causing chemicals in the built environment. In fact, there is a large body of occupational evidence, as well as epidemiological evidence, supporting the link between these chemicals and asthma. Since there is likely no single cause for asthma, it is important that we identify these additional potential exposure routes from building products to building occupants in order to begin to reduce these exposures as part of an asthma reduction strategy. This is especially important considering that the built environment is a place where we spend 90% of time, according to the EPA, and that these buildings persist for extended periods of time. We recommend precautionary action (minimizing use of asthmagens in building materials); an expansion of indoor air quality (IAQ) testing beyond the narrow set of VOCs they currently measure; and further research on building occupant exposure to these chemicals.
Aren’t exposures to isocyanates from building products only a concern when wet, not when cured, as in composite wood products?
Isocyanates in wet applied products are of high concern due to their un-reacted state, which has been found in many cases to cause skin and respiratory sensitization that can ultimately lead to asthma. These cases are prevalent among workers in occupational settings, but have also become an issue for consumers as more products – such as two-component spray polyurethane foam insulation, adhesives, and specialty paints – are made available. Wet-applied isocyanate-reactive systems are readily available to consumers. In using these products, people are reacting or “curing” isocyanate mixtures on-site – moving chemical exposures from controlled factory settings into their homes, offices and schools.
As reported by the EPA in their 2011 Methylene Diphenyl Diisocyanate (MDI) and Related Compounds Action Plan, “there is a growing availability of products, both consumer products and those labeled as ‘professional grade,’ that contain uncured MDI in retail and home improvement stores as well as for purchase over the Internet that are available to the consumer.” The EPA further describes that whether installed by professionals or do-it-yourself (DIY) applicators, there is concern that applicators as well as building occupants may be exposed to isocyanates from these site-reacted products.
As to the question of hazards posed by cured isocyanate products, such as polymeric MDI (pMDI) in composite wood products, many sources, including the EPA action plan, have generally stated that once completely cured – meaning that all the isocyanates have been reacted – they are considered to be inert and non-toxic.
However, this answer assumes that all isocyanates have been reacted and that no free isocyanate residuals remain. We have identified no published data to support this widely held assumption.2 On the contrary, multiple studies have reported findings of residual isocyanates in consumer products, including polyurethane foam products. There is little data concerning potential exposures from composite wood products, and testing of these and other cured isocyanate products are needed to determine if these products are in fact “inert.”
The Pharos research team welcomes engagement from manufacturers and other interested parties on this important question. Please send along any studies about the presence of isocyanates (or the lack thereof) in cured polyurethane building materials or other consumer products.
How does the HBN priority asthmagens filter work?
All of our filters in Pharos, including the priority asthmagens filter, screen out products that contain certain ingredients of concern. These filters not only cross reference intentionally added ingredients, but also look for and screen out chemicals that are possibly contaminating the product as residuals from the manufacturing process.
In order to ensure that products don’t pass through the filters without sufficient ingredient disclosure, a product must also have a complete content record in order to pass these filters. To have a complete Pharos content record "all intentional ingredients are listed in the Material Contents and fully identified.” This is done through collection of information from manufacturers as well as independent research by the Pharos staff on the products themselves as well as the ingredients, to determine process chemistry involved in the ingredients' manufacture. We assume that monomers, catalysts, non-reactive additives and contaminants may show up in the final product as residuals, unless data is provided from the manufacturer which document that these chemicals are not used in manufacture or have been tested for in the final product. (Find more information on Pharos disclosure standards/definitions here.)
Do any products pass the asthmagen filter in the Pharos Building Product Library? Do alternatives exist?
Yes, products in all but six product categories in Pharos pass our asthmagen filter, including: adhesives, ceiling tiles, composite woods, countertops, floor coatings, resilient flooring, wood flooring, paints, thermal insulation, and wall protection. Pharos users can identify those products that pass the filter by product category (as seen in the image below) or by the pro and con boxes found in each Pharos product profile record.
For those users specifying to avoid asthmagens in building materials, the Pharos team recommends taking these steps:
1. Identify products which have Indoor Air Quality (IAQ) certifications, preferably those that meet or exceed the CA 01350 standard.
These can be easily identified in Pharos – any product that has a VOC score of 6 or more will meet the CA standard. While the IAQ standards do not cover many of the asthmagens that we found to be of highest concern, these certifications are still an important tool for identifying healthier materials since they are able to capture many other health impacts. Therefore, the Pharos team believes this is an important first step for anyone specifying to reduce toxicants in the products they use, especially considering that asthmagen-free alternatives aren’t currently available for every category in the Pharos Building Product Library.
2. Screen products for asthmagens using our new filter in Pharos, which captures our list of top priority asthmagens.
If any asthmagens are present (high or low priority), the Pharos team recommends engaging with the manufacturer to learn more about the use of these asthmagens in the product and whether they have done any testing on the potential for exposure through the lifetime use of the product.
Thanks to our Pharos users for their interest in this topic and for their questions. We welcome further conversation on this topic by contacting us.
1 “Orthodox views regarding associations between allergy/asthma and feather pillows and bedding fitted carpets and rugs, dust mites and other environmental factors have also been brought into question.” (Krone, CA and TD Klinger. “Isocyanates, polyurethane, and childhood asthma.” Pediatric Allergy and Immunology 16, (2005): 368-379.) (Krone and Klinger 2005)
2 A 2005 review of isocyanates in cured polyurethane and links to childhood asthma stated that, “[b]ecause of the high reactivity of NCO [the isocyanate chemical sidechain responsible for its hazardous nature], it has been assumed that no residual NCO would remain in products by the time they reached the consumer. This assumption rarely has been questioned” (Krone and Klinger 2005). A later review of case studies on dermal exposure and isocyanate-induced asthma made a similar statement: “It is commonly believed that isocyanate-containing products polymerize rapidly, and once the product appears hardened, no unbound isocyanate species remain on the surface. However there are few published data confirming this” (Bello, Dhimiter, Christina A. Herrick, Thomas J. Smith, Susan R. Woskie, Robert P. Stricher, Youcheng Liu, and Carrie A. Redlich. “Skin Exposure to Isocyanates: Reasons for Concern.” Environmental Health Perspectives 115, no. 3 (2007): 328-335).