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. (This article is from the archives of the original Healthy House Institute, and the information was believed accurate at the time of writing).
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There are thousands of houses that contain cellulose insulation, yet only a relatively few occupants have complained of health problems as a result of its use. In order to understand why some people can be affected by this material, it is necessary to understand what it is made of and how it is installed.
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.
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.
The usual method of installing this material is to "blow" it in place with a machine. The bags of insulation are dumped into a hopper where it is mechanically fluffed up. A blower then forces it through a long hose. The insulation installer can use the hose to deposit the material directly in an attic. It can also be installed in existing walls by drilling one inch holes in the siding and blowing it inside the wall, into the stud spaces. The holes are then sealed with plastic or wooden plugs. Sometimes it is installed in walls by drilling the holes through the interior plaster or drywall.
In new construction, cellulose insulation can easily be blown into an attic but other materials are easier to install in new walls. In some cases, the insulation can be mixed with a glue (which may have its own health effects) and sprayed into the stud spaces before the interior wall covering is attached.
Cellulose insulation is well suited to being used in existing houses that were originally built without any insulation at all. These older houses were usually not built very tight because the building materials used in the past simply resulted in drafty houses. They may also have been remodeled or added on to over the years. As a result, there will be many small openings in the walls, floor, ceiling, etc. where the air simply blows through on a windy day.
When cellulose insulation is installed in such a house it may be blown into the living space through these holes. It is not uncommon to have a pile of insulation on the floor in the vicinity of each electrical outlet or near windows, since these are prime locations for air leakage. Sometimes there are large holes in the wall due to incomplete remodeling. These may be behind kitchen cabinets or in closets. Large amounts of insulation can enter the house through such holes.
The key to using potentially harmful building materials safely is to keep them out of the living space. In new construction, this is fairly easy to do by sealing openings where insulation could reach the occupants. However, in sealing up a house in this way, the house may be so tightly constructed that it needs some type of ventilation system to provide fresh air. Without a continual supply of clean air, a tight house will soon be filled with stale, polluted air.
In an existing house, extra care should be taken to insure that the cellulose insulation is only deposited inside the walls or in the attic, so that it cannot get into the house. An experienced and insured contractor should be used, and there should be an employee inside the house at all times in order to determine if any insulation is filtering in. As soon as any insulation is noticed indoors, they should shut off the blower and remedy the situation before proceeding. The occupants should not reenter the house until any insulation has been thoroughly cleaned up. Even then, they should be aware of any unusual symptoms for the next several weeks.
Cellulose insulation can be a very satisfactory insulating material if it is used conscientiously. While most people may not be bothered at all by a little insulation dust in the house, there are thousands of people around the country who are more sensitive than the general population to environmental pollutants. Often, they cannot tolerate even low "everyday" exposures to such things as exhaust fumes, printing ink, artificial fragrances, etc. For someone known to have increased sensitivities, extreme care should be taken when installing any type of insulation. For someone not now sensitive, caution should be taken to insure that such sensitivities do not develop in the future.
(Author's note: This article has been used by suppliers of fiberglass insulation to promote their product as being healthier than cellulose insulation. These people ignore the article on fiberglass insulation that I have written, which discusses its possible negative health effects. In spite of the potential negative health effects of both products, my point all along has always been that, if you build a tight house, the insulation (no matter what it is) will stay in the building cavities, and have no effect on the occupants. JB)
(Note: The views expressed in this article are those of the author, and do not necessarily represent those of The Healthy House Institute, LLC.)
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