Published in Environ, #11 (1991), p. 11.
by John Bower (Copyright 1991)

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 devastating health problems. People have been made ill and forced to abandon their homes after they were insulated with this material. Before you have it installed in your house, you should consider the following families' experiences.


In early 1987, a California family planned to buy the house that they were renting. In order to obtain an FHA mortgage, the house had to be insulated prior to loan closing. As many other homeowners all over the country had done, they chose cellulose insulation because of its cost, insulating value, and ease of installation.

While the cellulose insulation was being installed, the wife, their four year old son and their pet German Shepherd remained in the house. She had asked the installers if that was wise, and was informed that the insulation was perfectly safe and that there was no reason for her to leave while they were working. As it was being blown into the walls, the interior of the house had a considerable amount of insulation dust floating around in the air. While it smelled a little strange, and would later be vacuumed up, it was of no particular concern because, after all, it was "perfectly safe."

Over the next few months, all of the family members began having various symptoms, with the wife's health deteriorating markedly. Less than two weeks after the work was completed, she began to have breathing problems for the first time in her life. She also began to get a painful rash and felt generally unwell. Her skin began to turn yellow and her hair fell out in clumps. With her health rapidly declining, and on the verge of exhaustion, her physician said that she might have systemic lupus Erythematosis, a chronic inflammatory disease of the connective tissues. Since her son was having similar symptoms, he suggested that it was probably "genetic lupus," and that it was a coincidence that they both developed symptoms at the same time. Dissatisfied with his speculation, she consulted other doctors, none of whom could tell her what was wrong.

Her hair was now falling out by the handful and her young son had lost all of his hair. Her body felt as if it was on fire because of the rash and her breathing difficulties worsened. She was getting continually weaker and looked as if she had AIDS. By the time three months had passed, she was too weak to continue at her waitressing job. Now, spending more time at home, she noticed that her breathing was easier when she was outdoors in the fresh air. Immediately she knew that the her ill health was related to the house and that the newly installed cellulose insulation must be the cause of her ills.

The walls of her bedroom had not been insulated and she found that she felt better when in that room. She immediately moved her son to another part of the house that did not have cellulose insulation. In the meantime, another physician had been running a battery of tests. Hair analysis showed high levels of boron and some arsenic. Another lab tested the insulation and found similar contaminates, as well as a high formaldehyde content. AIDS tests were negative as were most other tests. The final test showed that both her and her son's immune system was practically non-existent due to a chemical overload.

She spent over seven weeks in an intensive detoxification program only to lose about 25% of the poisons in her system. Her son and husband also went through detoxification. Today her health is only marginally better. There are periods of feeling well when her hair begins to grow back, then the symptoms return. Her son is somewhat improved, although he still occasionally loses patches of hair.

Since the insulation was installed, their German Shepherd has had two litters. Half of the first litter died at birth, with the remainder needing to be revived. Only one puppy from the second litter survived.

Because of all of their expenses, they have lost their health insurance, so further medical treatment is doubtful. Since the house was obviously the cause of their ills, they moved out and lost their investment. The insulation installer had no insurance, so a successful lawsuit probably wouldn't be worthwhile.


An Iowa woman contracted to have cellulose insulation installed in her home in February 1985. Besides filling the walls, the workers somehow managed to fill the ductwork of the heating system with insulation. The furnace fan then blew insulation all over the house. There was nearly 1/2" of insulation covering the entire house, with large piles near some heating registers.

The installers agreed that it was a horrible mess and it would take some time to clean up, but they assured her that the insulation was non-toxic and of no cause for alarm. That evening she developed flu-like symptoms which worsened with each succeeding day. By the fourth day, her tropical fish were all dead and the houseplants were on the decline. Then her 18 month old pet Labrador started convulsing.

Her physician diagnosed bronchitis, saying that it was nothing to worry about. However, the veterinarian thought the problems could be caused by the insulation and suggested that they move out of the house. When they moved temporarily into a local motel, the dog's health quickly returned and hers seemed to improve. Unfortunately, she noticed that she was now being bothered by such things as chlorine in the swimming pool, and automobile exhaust fumes. She had become chemically sensitive to very low doses of environmental pollutants.

At a cost of nearly $50,000, the house was thoroughly cleaned and the insulation was completely removed, yet, within ten days of re-entering the house, she felt worse than before. The house now stands empty pending the results of a lawsuit.

Since the insulation was inside the heating system, the high temperatures inside the furnace could have changed its chemical structure and caused it to volatilize unknown toxic fumes into the air. Therefore, it would difficult to determine just what particular chemical damaged her health. She is no longer able to work and her future is uncertain.


About a week after having cellulose insulation installed, a 32 year old housewife began suffering from upper respiratory infections, sore throat, burning of the esophageus, coughing, skin rashes, hair loss, fatigue, severe mood swings, and suicidal depression. Because of the suicidal tendencies she was admitted to a psychiatric hospital.

About a month after the insulation was installed, her husband became severely depressed. A test revealed that his urine borate level was elevated. Their two children exhibited symptoms of nasal congestion, coughing, cold symptoms, growth retardation, weight loss, ear infections, respiratory infections, and poor appetite.

Within a month of moving out of the house, the entire family's health dramatically improved, even though the father's urine borate level remained high when tested nine months later.


A 56 year old housewife with mild emphysema who smoked 2 1/2 packs of cigarettes a day was not in optimum health, although she remained active. Three days after cellulose insulation was installed in her home, she had to be admitted to the hospital because of respiratory failure.

Her husband, who was previously in good health, suffered coughing, nasal congestion, choked up feelings, violent headaches and watering of his eyes. He developed pneumonia about two weeks after the insulation was installed.

They have since had the insulation removed from their house. This was an expensive and time consuming process involving the partial dismantling of the house. In spite of this, the wife's health continued to deteriorate. However, the husband's health has improved.

The level of boron in the home was measured at 0.6 mg. per cubic meter, which was below the threshold limit value for the workplace of 1.0 mg. per cubic meter. This level may be deemed safe by regulatory agencies but it was obviously a dangerous level for these two individuals.


A 28 year old housewife with no specific health problems complained of being extremely sleepy within a week after cellulose insulation was installed in her home. During the next month she experienced symptoms of weight loss, painful leg nodules, skin rashes, painful bleeding gums, depression, suicidal tendencies, irritability, diarrhoea, abdominal pain, chest pain, and coughing. After moving out of the house, her health improved.

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 severely 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 sulphide, 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, sulphur 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 fibres 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. Probably as a result of their exposure to many of these chemicals, workers in the pulp and paper industry show an increased incidence in various types of cancer. 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, or fish 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 odour 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. In industry, dye workers have an increased incidence of several types of cancer. The coloured inks and dyes are much more toxic than the black ones. Burning the coloured pages from the Sunday newspaper results in very dangerous fumes being given off.

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 mould 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 sulphate, aluminium sulphate, 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. This involves more work to patch the holes once the installation is complete, so it is not often done.

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 remodelled 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 will 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 remodelling. These may be behind kitchen cabinets or in closets. Large amounts of insulation can enter the house through such holes.

If you can get them to talk "off the record," every cellulose installation installer will be able to tell you about a colossal mess that he created. There are cases where interior wall panelling was literally blown off the wall because the installer was using a blower with too much pressure. One installer told of a house that had a dropped ceiling. Unknown to him, the original ceiling had been removed. As he blew insulation into the walls from the outside, he inadvertently was filling the space above the dropped ceiling. Suddenly the entire ceiling collapsed from the extra weight, filling the room with insulation.

The key to using potentially toxic 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 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 re-enter 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. If no symptoms develop, the installation is probably satisfactory. If some symptoms begin to develop, the only way to be sure if they are related to the house is to move out temporarily and see if health improves. If symptoms subside when away from home but return when re-entering the house, the new insulation should be suspected.

Cellulose insulation can be a 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 fibreglass insulation to promote their product as being healthier than cellulose insulation. These people ignore the article on fibreglass insulation that I have written, which discusses its negative health effects. In spite of the 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)