Eight of 16 upholstered furniture flame retardants pose little or no health risk, says a new report from the National Academies' National Research Council (NRC). Eight other flame-retardant chemicals that may be used to treat furniture fabric should be studied further.
The conclusions could open a large market for makers of the eight chemicals. The US Consumer Product Safety Commission (CPSC) is considering mandating treatment of residential furniture to prevent upholstery fires, which annually claim about 100 Americans, most of them children. Under the ruling, fabric makers would have to apply chemicals to several hundred million square yards of fabric annually.

A request by the National Association of State Fire Marshals prompted Congress to ask NRC to study the health risks posed by exposure to flame-retardant chemicals.

"We concluded that eight of these 16 chemicals can be used to treat residential furniture with minimal risk to human health," says Donald Gardner, president of Inhalation Toxicology Associates Inc. (Raleigh, NC) and chair of NRC panel that wrote the report.

"Studies are needed on the other eight, however, to find out how much exposure people would actually have to these chemicals if they were used on home furniture. If a high amount of exposure is likely for a particular chemical, then further studies on its toxicity may be warranted," Gardner continues.

eight chemicals deemed safe are:
decabromodiphenyl oxide;
alumina trihydrate;
magnesium hydroxide;
zinc borate;
ammonium polyphosphates;
phosphonic acid;
tetrakis hydroxymethyl phosphonium chloride.

eight questionable chemicals include:
antimony trioxide;
antimony pentoxide and sodium antimonates;
calcium and zinc molybdates;
organic phosphonates and cyclic phosphonate esters (dimethyl hydrogen phosphite);
tris (monochloropropyl) phosphates;
tris (1,3-dichloropropyl-2) phosphate;
aromatic phosphate plasticizers (tricresyl phosphate);
chlorinated paraffins.

Few studies have covered exposure flame retardants in residential furniture. As a result, the panel chose to intentionally overestimate possible exposure. For example, it estimated skin exposure by assuming 25% of the upper torso of an adult sitting on a treated couch six hours every day. It did not consider protection offered by clothing. In addition to skin contact, the panel assumed adults would inhale fabric particles or vapors and that children would suck on the fabric.

The panel then reviewed the literature to identify adverse health effects associated with flame-retardant chemicals. It compared the highest dose at which no adverse health effects were observed and the lowest dose at which a chemical caused harm against its worst-case exposure estimates. This allowed it to make a judgment about a whether a particular route of exposure could present a health risk.

Although toxicity data for some of the safe chemicals were inadequate for certain routes of exposure, the panel found them safe even under worst-case exposure assumptions.

On the other hand, it did not have enough data to make a decision on the other eight flame retardants. It recommends further study to determine the potential for exposure and possible health effects. If studies show actual exposures are lower than its estimates, further toxicity studies may prove unnecessary.

Given the conservative nature of its assumptions, the panel does not necessarily expect adverse effects from the eight problematic flame retardants. It also notes that an overly cautious approach might adversely affect public health if the public avoided using flame retardants (which reduce death by fire) because of minor health risks predicted by conservative models.

The National Academy Press plans to publish the study, Toxicological Risks of Selected Flame-Retardant Chemicals, in June. CPSC funded the study.