Yep, maybe installed incorrectly but Borax is not the only thing in blown-in insulation and Borax is an irritant and some develop allergies. There is also ammonium sulfate and whatever else is in the recycled cellulose. Plus cellulose itself has issues as identified in the Oxford Journal :
"In the in vivo tests cellulose fibres produced harmful effects, including tumours."
http://annhyg.oxfordjournals.org/content/46/suppl_1/81.full.pdfMaybe if you seal your attic properly you'll be fine but between floors there are a lot of cracks and soundproofing between floors is still a recommended use. And even if you seal there are off-gassing issues identified in the French studies.
I agree fiberglass also has issues.
http://www.greenbuildingadvisor.com/blogs/dept/green-building-curmudgeon/it-time-stop-insulating Maybe the ISO certifier is incorrect and out to lunch, seems a bit suspect, but the other report is not from the ISO folks. It is from the European Chemicals Agency, and they did a 171 page report on the chemical issues with cellulose insulation.
https://echa.europa.eu/about-us/who-we-are/mission "In France, the Directorate of Housing, Urban Planning and Landscape (DUHP) was informed by the European Cellulose Insulation Manufacturers Association (ECIMA) and the French Scientific and Technical Centre for Building (CSTB) that a growing number of householders were complaining about an ammonia smell following the installation of cellulose insulation for sound or thermal insulation in their homes. In 2012, ECIMA had recorded 115 reports and had conducted in situ measurements indicating ammonia concentrations in air of up to 5 ppm...
In addition, there are few human data on the toxicity of cellulose fibres. Occupational exposure can induce effects on the eyes and
mucous membranes of the airways. It would therefore be worthwhile conducting a risk assessment for these fibres. One patient refused to have the insulation replaced by insulation containing boron salts, given his knowledge of the reasons that led to its withdrawal. There is therefore a fundamental problem with the nature of the insulation products to be used, to which patients and especially professionals are exposed for many years."
The insulation industry itself admits there has been inadequate testing:
http://www2.owenscorning.com/literature/pdfs/BI502.pdf "An inadequately tested or analyzed product should not be deemed safe or free from health risks simply because its manufacturer has refused or failed to test its product. Indeed, failure of a product to be adequately tested by its manufacturer should be a critical factor in determining that a product should NOT be considered for use. Dr. J.M.G. Davis of the Institute of Occupational Medicine Ltd. reaffirms this concept in the following statement: “It is disappointing to find that…some fibre products are being manufactured and promoted as safe when this really means they are untested. A current example of this concerns the increasing use of materials based on cellulose fibres.” Davis’ statement is equally applicable to all other types of insulation. JMG Davis, “The need for standardized testing procedures for all products capable of liberating respirable fibers: the example of materials based on cellulose,” British Journal of Industrial Medicine, 1993: 50: 187-190. Fifteen years after this admonishment, cellulose insulation manufacturers have still not adequately tested their products."
I have nothing to sell to you, nor do I have some antivax weird agenda. In real life I'm a lawyer and pretty skeptical. I will say that when we sold our house a year after the installation I was glad to move despite the ideal location. My one son and I developed asthma, which later resolved in our new house which did not have blown-in cellulose insulation. YMMV and this is anecdotal and could be coincidental but I, for one, would never ever buy a house with blown-in cellulose insulation based on this unscientific experience.