I am writing in response to questions raised about the safety of borates used as flame retardants in mattresses. As a toxicologist and a parent, I agree that mattresses should be fire-resistant without posing a risk to human health. Fortunately, mattresses containing borate-treated cotton batting pose no health risk to humans.

Borates are ubiquitous in nature, and they are essential for plant growth. For most people, the single largest daily source of exposure to borates is the ingestion of naturally-occurring borates in foods, including all fruits, vegetables, and nuts. The National Institute of Health’s Food and Nutrition Board recently established an Upper Limit of exposure to dietary boron of 20 milligrams per day (equivalent to 57 milligrams of boric acid). For most Americans, the average dietary intake of boron is 1 to 3 milligrams per day (equivalent to 6 to 17 milligrams of boric acid). Many nutritionists believe that Americans would benefit from more borates in their diet, and many popular multi-vitamins (e.g., Centrum) intentionally add borates.

Borates are natural substances that have been used for decades to make glass (e.g., Pyrex cookware), ceramics, fiberglass, laundry detergents (e.g., 20-Mule Team Borax), and personal care products, such as contact lens solutions. Human exposure to borates from these products is less then dietary exposure to borates. In comparison, exposure to borates in mattresses is even lower.

There is virtually no consumer exposure to borate in treated mattresses. The borate is used to treat the cotton batting inside the mattress. Unlike the cotton batting, the surface of the mattress is not treated with borate. Therefore, there would be no contact with or exposure to borate even if a person slept directly on the mattress surface without a mattress bad or sheet. Unless a person were to cut open the mattress and eat the cotton batting, no exposure to borate would occur. Borate is not volatile, and cotton batting inside a mattress would not be inhaled. Dermal absorption of borate is insignificant. In short, a person will be more exposure to borate by eating an apple or orange than by sleeping on a mattress with borate-treated batting.

Ironically, without borate, there would be no cotton batting, since cotton could not grow without this essential plant element. No borate, no cotton! Even untreated cotton will contain borate – just less than treated cotton.

But aren’t borates toxic? Not at the levels found in mattresses. Borates are classified as having "low acute toxicity" – which means they are about as toxic as table salt. Even workers in a borate mine have not shown any detrimental effects due to absorption of borates. The common use of borates in a wide variety of consumer products is a reflection of their relative safety.

In summary, borate-treated cotton batting in mattresses is not harmful to health. In fact, a person will receive far more exposure to naturally-occurring borates by eating fruits and vegetables than by sleeping on a treated mattress. Sleep well at night knowing that your mattress containing borate-treated cotton batting is safe.

F. Jay Murray, Ph.D., DABT

San Jose, CA