Thanks to all who attended our webinar “When is it "green"? Preventing the Toxic Effects of Spray Foam Insulation”! This webinar was co-presented by Healthy Building Network researchers, Jim Vallette and Rebecca Stamm, and Greg Siwinski, a practicing field industrial hygienist with the Occupational Health Clinical Center (SUNY Upstate Medical University). If you missed the webinar or would like a refresher, the video is available here.

We had several questions from attendees at the end of the webinar -- some we were able to answer and others we ran out of time to discuss. All the questions and answers are now available below.  

Question 1: How is this product different from spray foam used for caulking / air sealing? Do you have any information on the health risks, if any, of one part expanding foam?

Rebecca: The spray foams that we focused on in the webinar are two part systems that are mixed on site and used to insulate large areas. Two-part spray foam is sometimes used for air sealing gaps as well, but commonly, one-part spray foam is used for smaller air sealing jobs. One-part spray foam is pre-mixed and comes in a single container. The chemistry of these two types of products is similar, so a lot of the life cycle concerns are the same.  

While some of the reaction has already taken place in the can for one-part products, it is unclear how much unreacted isocyanate remains when the product is applied. Exposure to asthmagenic isocyanates thru inhalation or skin contact is still possible with one part spray foams. If you look at the Safety Data Sheets (SDSs) for these one-part products, they recommend ventilation and often a respirator. A supplied air respirator is needed if air levels are above set exposure limits - which Greg pointed out are very small for isocyanates. This is a particular concern in confined, poorly ventilated areas, like attics. Protection against skin contact is also necessary for the one-part foams. Some manufacturers estimate that it can take 8-24 hours for one-part foams to cure.

One-part spray foams also contain other chemicals of concern, including the chlorinated flame retardant TCPP also found in two part systems (which is considered a very high concern to avoid because of its persistence and toxicity and its ability to migrate from products) and an isobutane blowing agent (which is a carcinogen and mutagen). Fireblock versions contain additional flame retardant - commonly chlorinated paraffins that are developmental hazards.

Question 2: It’s very difficult to fire stop and air seal without spray foam products. What do we do about air sealing?

Rebecca: When a foam sealant is needed, we recommend preferring pre-formed products like a foam sealant tape whenever possible. For other applications, caulk-type sealants are preferred, particularly low VOC acrylic sealants and acrylic intumescent firestop sealants. Some one part non-isocyanate spray foam products are available, but we don’t currently know enough about their contents to be able to determine whether they are preferable from a health perspective. We suggest asking manufacturers of these products to disclose their contents through programs like the Health Product Declaration and Declare. More information on hazardous content of air sealing products and preferred sealants from a health perspective will be included in the Healthier Affordable Building Materials Guide coming out later this year.

Question 3: Is your stance not to use SPF in cavity walls as insulation, or avoid as air sealing products (plugging up holes, rim joist) all together?

Rebecca: We absolutely recommend not to use SPF in wall cavities. We also recommend avoiding spray foam for air sealing applications whenever possible. For many applications, there are alternatives (see answer above). Unfortunately, some of these products may cost more per linear foot sealed than one-part polyurethane spray foam. There is a need for disclosure on non-isocyanate spray foam and development of healthier products for some air sealing applications.  

Question 4: It was my understanding that HFOs had zero ODP and less than one GWP. At least the Solstice blowing agent by honeywell says so.

Jim: Yes, in terms of their direct ozone depletion potential (ODP), that is correct. The problem is that the HFOs (hydrofluoroolefins) in use as the new generation of blowing agents require carbon tetrachloride as a feedstock. Back when they were negotiating the Montreal Protocol, which was designed to phase out ozone depleting chemicals, the chemical industry got a loophole for carbon tetrachloride (CTC), saying it is an industrial intermediate that is used up entirely in the production process. What we are seeing from Toxics Release Inventory (TRI) data and other evidence around the world is that a lot more ozone depleting chemicals are being released by the chemical industry than we were previously aware of. Once the new Honeywell HFO plant came online in Baton Rouge, we’ve seen a huge increase in carbon tetrachloride releases - exponential increases in releases from that plant and there is a huge new plant being built in Texas as well. That’s going to be one of the biggest sources of ozone depletion in the world. So, it’s correct that the HFOs themselves have zero ODP, but the carbon tetrachloride feedstock is a very potent ODP. CTC has an ozone depletion potential of 0.82, which makes it nearly as potent as several chlorofluorocarbons (CFCs).

Question 5: You mentioned HFCs in SPF products/blowing agents. Can you send us your data sources on this? There some SPF products out there that are declaring low/no HFCs. What if you use water as the blowing agent?

Rebecca: Open cell SPF typically uses water as a blowing agent, while closed cell SPF typically uses HFCs. The most commonly used HFC in SPF is HFC-245fa or 1,1,1,3,3-Pentafluoropropane (CAS: 460-73-1) -- you can see HBN’s Common Product record for SPF for sources. Some closed cell SPF products have moved away from the use of HFCs. Most of these use HFOs, which have the life cycle concerns that Jim mentioned in the webinar and the above answer. There is at least one closed cell SPF on the market that uses water as a blowing agent. Both products using HFOs and water as blowing agents may be advertising ‘no HFCs’. While water is a preferable blowing agent compared to HFCs or HFOs, SPF products that use water still contain the primary chemicals of concern - isocyanates, amines, tin catalysts, and chlorinated flame retardants.

Question 6: Can you address why fiberglass options are preferred to cellulose or cotton alternatives?

Rebecca: Cellulose insulation is still a good option from a health perspective. The reason that we prefer fiber glass over cellulose is the boric acid that is used as a flame retardant and pesticide in cellulose and cotton insulation. Government agencies have raised fewer human health concerns for boric acid than for halogenated flame retardants, but boric acid is still a potential concern because of the associated developmental and reproductive hazards and the large quantity used within the insulation. Exposure to boric acid is of particular concern during installation and if dust enters the living space. More research is needed on potential migration of boron-based flame retardants.

Question 7: Please provide some additional health related information about MDI used in engineered wood products. Does it continue to off-gas after it cures? Is it also a high fire hazard?

Jim: While many of the life cycle concerns raised in the webinar for methylene diphenyl diisocyanate (MDI) still apply for it’s use in engineered wood products, these products are reacting in a factory setting, so a more controlled environment than in spray foam applications. Huntsman, one of the world’s main producers of isocyanates, asserts that “there is no need for concern regarding exposure to consumers if MDI bonded composite wood products are used in buildings or homes.”  

But published results of independent field tests for isocyanate emissions from engineered wood products are nearly non-existent. Indoor air quality tests for building materials do not include isocyanates. A recent Danish literature review concluded that, “the data are too scarce for making general conclusions regarding presence of residual” isocyanates in consumer products.

We are not aware of any increased fire hazard associated with engineered wood products using MDI-based binders. However, activities such as cutting may heat these building materials enough to release isocyanates and other degradation products.

Question 8: If a product has a health product declaration does that help?

Jim: It certainly helps to have more of a paper trail for what is in any building material. It’s vital that the declaration be disclosed completely, down to 100 ppm, including residuals. We are seeing a lot of products where the ingredients below one percent are often some of the most potent. So if a Health Product Declaration is declared to that level it can be helpful in the scenario where Greg is talking about, for fire fighters, so they know what’s in that foam. It can also be helpful for selecting healthier products within a category, but we need to take a step back as well and look at it in the context of that product in the universe of other alternatives that pose fewer health challenges. Because we have a pretty good understanding about the contents and health concerns of spray foam versus other types of insulation, we still wouldn’t recommend using SPF, even if it has an HPD.

Question 9: Is there a credible, independent organization training and certifying installers? (referenced in 2nd to last slide)  If so, for those of us who have influence over project specification language, where would we find that information?   

Greg: Other than industry provided trainings in New York State which I have concerns about, I am not aware of other possible training resources. I have not investigated other possibilities but that would be a useful endeavor.  

Question 10: You didn’t mention health surveillance / medical surveillance.  Shouldn't this be mandatory? I know that if you do a risk assessment using COSHH Essentials and the chemical used is an occupational allergen then there is a requirement for health surveillance. This is a UK HSE requirement.

Greg: A well thought out medical surveillance program for spray foam insulation workers should be required. However, this is not required in the US and given the current state of affairs I would not expect this anytime soon. As you know, medical surveillance is a secondary form of prevention which can be used to augment primary prevention (exposure controls) to ensure that any disease process is caught early. Efforts to develop a reliable medical test such as a blood test to determine early sensitization to isocyanates are still ongoing. That leaves us with typical medical surveillance focusing on the respiratory system using pulmonary function testing etc. I would argue that more attention on primary prevention like product substitution, ventilation, air-line respirators etc. is needed since the small insulation contractor are unlikely to provide medical surveillance.

Your comment is a valid one and medical surveillance should be used to augment effective exposure control methods. Perhaps the suppliers of the SPF materials should require effective exposure controls and medical surveillance as a requirement for the use of their products. I would add that when medical surveillance is used it must be done by an informed and independent medical provider whose primary interest is the patient.

Question 11: Considering existing buildings/homes that may have used this type of insulation method, what type of IAQ [Indoor Air Quality] testing would your team recommend in order to detect any (harmful) levels? For example, direct-read device or canister to lab test? Are any of the tests more reliable and accurate than others? What type of continuous monitoring would you recommend (if any)?

Greg: I am not aware of a standard sampling approach to evaluate a spray foam project. Several of our patient hired building scientist/testing consultants to measure the air in the homes and foam and the results from those efforts are mixed. It appears that a PID device may provide some useful information on foam off gassing and substrate off gassing but that is based on very limited experience. Perhaps the industry has an established protocol that might be worthwhile to review critically.

Rebecca: The American Society for Testing and Materials (ASTM) has proposed several new standards (not yet finalized) for measuring emissions from SPF that cover a range of chemicals of concern. A list of the proposed standards is available here. One of these proposed standards states that it is “primarily intended for measuring chemical emissions from specimens in environmental test chambers or micro-scale chambers; however, it could also be used for analysis of air samples collected in the field, that is, for monitoring emissions from SPF that has been applied in residential or commercial buildings.” We can’t currently speak to the reliability or accuracy of any of these proposed test methods.

Question 12: I have some real concerns with fiberglass being listed as a healthy building material. Please provide some scientific research that backs up that claim. My experience is quite different and I would not recommend it as a product.

Rebecca: Some specialty glass fibers are carcinogens, but those used in fiber glass and mineral wool insulation are biosoluble (readily dissolve in the lungs) so do not have this associated hazard. However, fiberglass insulation still needs attention from a worker exposure point of view. Always follow good industrial hygiene principles such a good handling methods, ventilation, and adequate respiratory and skin protection.

Detail: In 1988, the International Agency for Research on Cancer (IARC) released a Monograph on Man-made Mineral Fibers. This study concluded that mineral wool fibers (including glass and rock/slag wool) were “possibly carcinogenic to humans”. In 2002, new data from additional studies were reviewed and incorporated into a new IARC Monograph which concluded that the type of mineral wool fibers used in insulation are “not classifiable as to their carcinogenicity to humans”. In 2011, both the National Toxicology Program (NTP) and the California Office of Environmental Health Hazard Assessment (OEHHA - the organization that administers Prop 65) made a distinction in their listings between biosoluble glass fibers and certain other glass fibers that are inhalable/biopersistent. This change meant that the cancer hazard association and a cancer warning, which was previously required on packaging, no longer applied for products using biosoluble fibers. The prior labeling of fiber glass insulation products has led to some confusion in the industry, but the scientific consensus is that the biosoluble glass fibers that are used in insulation are not considered carcinogens. See the International Agency for Research on Cancer (IARC) Monograph on Man-made Mineral Fibers from 2002 for more details.  

As noted above, fiberglass insulation still needs attention from a worker exposure perspective. It is always important to follow good industrial hygiene principles such a proper handling methods, ventilation, and adequate respiratory and skin protection. Glass and mineral wool fibers from insulation can cause reversible skin, eye, and lung irritation so manufacturers recommend using skin protection (long sleeves, long pants, and gloves), eye protection, and a dust respirator.

Additionally, fiber glass insulation typically contains around 0.5-1.5% of a carcinogenic de-dusting oil, used to keep dust levels down during manufacture and/or installation. While this is still a concern, in the realm of currently available insulation products, fiber glass insulation is one of the highest ranked from a health perspective because of the relatively low quantity of hazardous content. Various facings can add additional hazards to fiber glass insulation, but they are still relatively highly ranked in the spectrum of insulation products. See our hazard spectrum on HomeFree for more information comparing the hazardous content of different types of insulation.  

Question 13: Has a similar in-depth evaluation been done for mineral fiber insulation?

Rebecca: Most mineral fiber insulation uses a urea phenol formaldehyde binder. Urea phenol formaldehyde, like other formaldehyde-based resins, releases formaldehyde (a potent carcinogen and asthmagen) into living spaces over time. Starting in mid-2017, some mineral fiber batt insulation is becoming available without formaldehyde-based resins and should be preferred when using mineral fiber batts. See the answer above for more information on mineral fibers.

Greg: In terms of occupational hazards, it is always prudent to error on the side of caution -- less exposure is always better. Mineral fiber insulation should receive respect during its handling and installation by workers since the test of time (i.e. epidemiology) is typically used to prove or disprove long term health risks associated with a product’s use.  

Question 14: Do you know the frequency of improper install with spray foam, and the risks associated with proper install, since most of the research was based on customer complaints where it was established that the installation was improper?                       

Greg: Please keep in mind that the patients who presented to our center (Occupational Health Clinical Center - SUNY Upstate Medical University) had adverse health effects and they were referred to us. Therefore, we do not see all cases from these sorts of activities. We really do not know the magnitude of the problematic spray foam jobs. Are we seeing the tip of the iceberg or the tip of a ice cube? We honestly do not know. However, other examples of adverse health effects are being reported in other regions of the US. Also, given the known health risks from the spray foam ingredients and the methods being used to do this work is really the driving force to raise the alarm of our concern.

Rebecca: Even properly installed spray foam insulation has greater associated hazards than most other insulation products. There are highly hazardous chemicals that do not react, so are present in the final product regardless of the installation - for example, a semi-volatile halogenated flame retardant and non-volatile organotin catalyst (which is persistent, bioaccumulative, and toxic). The EPA also warns that the potential for off-gassing of volatile chemicals from spray polyurethane foam is not fully understood and is an area where more research is needed.

A National Institute of Standards and Technology (NIST) study tested four foam samples, including two foams sprayed in factory settings under controlled conditions, one sample applied in a NIST test facility, and one sample from a home. The authors report that many chemicals were emitted to the air from each sample tested and the emissions were highly variable. TCPP, the commonly used chlorinated flame retardant, was detected in emissions from all four samples tested. More details of this study can be found here.