What’s in Blown in Cellulose Insulation

Due to several current projects I have encountered I believe it’s important to touch on a couple of issues that every homeowner should be aware of to protect their home and their health.

Cellulose Insulation with Boric Acid

I have a client who has been experiencing health issues from a pest company blowing in cellulose insulation with boric acid.  Their home is over 100 years old.  The pest company who now is also an insulation company did not do a building evaluation prior to using the blown in cellulose with boric acid or talk to the client about their potential sensitivities.  The home being over 100 years old lacks insulation in several building cavities of the home.  As the pest company blew in cellulose with boric acid in the attic area this fine particulate also traveled to the other building cavities, ceilings, walls, etc.  My client has been experiencing issues directly related to exposure to boric acid since.  The pest company removed the blown in cellulose from the attic area but the building cavities cannot be remediated without tearing out walls.   The attic has been remediated and the interior of the home cleaned.  The problems still persist.  

Cellulose insulation has been considered to be a very safe product to use in houses. Unfortunately, like so many other modern building materials that we often take for granted, it can sometimes be responsible for problems.

Cellulose is a carbohydrate, a fairly inert component of plants. Cellulose insulation, however, is far from inert. It is such a complex mixture of chemicals that it would be virtually impossible to determine an accurate listing of components. The primary ingredients are ground newspapers and boron compounds such as boric acid and borax. While newspapers consist mainly of cellulose that is derived from trees, they contain a wide variety of potentially toxic chemicals.

When wood is transformed into cellulose such things as sodium hydroxide, sodium sulfide, and chlorine compounds are added during processing. A variety of chemicals can be produced as the wood chips are broken down chemically. Some of these by-products are: formaldehyde, chlorine, fluorine, lead, iron compounds, sulfur compounds, cadmium, nitric oxide, methane, etc. While the goal is a pure product called cellulose, the material that leaves the pulp mill is contaminated with many of the chemicals that are either added to the wood fibers or created as a result of chemical reactions.

By the time the cellulose is made into sheets of paper, it may contain dyes, synthetic resins, gums, talc, varnishes, and solvents. Since paper is far from being pure cellulose, it is no wonder that there are many sensitive people being recognized who are bothered by it.

A larger problem with newspapers is the ink that is used. Printing inks can be complex preparations containing petroleum oil, vegetable oil, as well as various natural or synthetic resins. Many different solvents can be used in ink, including turpentine, toluene, alcohol, and xylene. Solvents tend to evaporate, accounting for much of the odor given off by a fresh newspaper, a smell that can easily cause reactions in sensitive people. Other additives in ink include pigments, driers, waxes, lubricants, perfume and dyes.

The paper used in newspapers is called newsprint. It is a very low-grade, inexpensive paper. As such, newsprint may be more likely to contain impurities than a more costly parchment or bond paper.

Cellulose insulation could, therefore, be bothersome if it was only made from newspapers, but it could also be made with other recycled papers such as magazines or cardboard boxes. The inks used years ago were more toxic than those in use today and recycled paper could have residues of the older inks. Paper to be recycled could get contaminated with mold or various toxic chemicals depending on where it has been stored.

In order to make it fire resistant, cellulose insulation is treated with various chemicals, primarily boric acid and borax. Other compounds such as ammonium sulfate, aluminum sulfate, ammonium phosphate, and zinc chloride may also be used. These chemicals usually account for about 20% of the final product.

Technical Faxsheet on Boric Acid:


Permanency of Boric Acid used as a Fire Retardant in Cellulosic Insulation:


In order to have the maximum insulating value, the paper is ground up into a very fine powder that can easily float around the air. This powder, containing residues from the original papermaking process, the different inks used each time it was recycled and the added chemical compounds, is easily inhaled. Some boron compounds can be absorbed through the skin.

If you would like more information on blown in cellulose and the health effects please contact TP Environmental 207-991-0171

Let’s Clear the Air