Why studying flame retardants is a good idea

Last week, we wrote about the EPA’s announcement to conduct a risk assessment of 23 chemicals. Most of the chemicals the EPA is reviewing are from a class of chemicals known as flame retardants. These chemicals are widely used in consumer products to slow the speed at which those products burn in the case of fire. The idea is that retarding, or slowing, the speed at which items burn may save lives by giving people a wider window of opportunity to escape.

However, flame retardants are the subject of increasing scrutiny. One type of flame retardants—PBDEs—are known toxins, and are currently being phased out in the United States. The Duke Superfund Research Center’s own Heather Stapleton testified before the US Senate Committee’s hearing on the Toxic Substances Control Act (TSCA) about her research on PBDEs and evidence of their detrimental effects on human health.

Why is interest in understanding the effects of flame retardants on the rise? New types of flame retardants are replacing PBDEs, and little is known about their effects on human health to date. Many of the reasons scientists are concerned about flame retardants are similar to the reasons that DDT was banned in the US during the 1970s.

Flame retardants are ubiquitous. They are used in furniture, building materials, electronics, and baby products. Like DDT, flame retardants are persistent—they stay in the environment for a long time without breaking down into safer compounds, and they accumulate in our bodies. Due to their wide use for over 30 years, flame retardants have made their way into everything from dryer lint to our food to human blood and breast milk.

Couple all of this with known neurological and developmental effects of certain flame retardants. PBDEs, which are among the most well-studied flame retardants, have been linked to cancer. PBDEs can also impact on children’s health and development—such as low birth weight and IQ.

In our previous post, we mentioned 4 types of flame retardants on which the EPA will be able to conduct a full risk assessment under TSCA. These chemicals are TBB, TBPH, TCEP, and HBCD. We’ve compiled a list of how these chemicals are used and in which products below:

TBB (2-Ethylhexyl ester 2,3,4,5- tetrabromobenzoate)

  • Used in: PVC, neoprene, coated fabrics, wall coverings, adhesives

TBPH (1,2- Ethylhexyl 3,4,5,6-tetrabromo-benzenedicarboxylate or (2-ethylhexyl)-3,4,5,6 tetrabromophthalate)

  • Used in: polyurethane foam (in furniture and construction), baby products, wire and cable insulation, film and sheeting, carpet backing, coated fabrics, wall coverings, adhesives

TCEP (Tris(2-chloroethyl) phosphate)

  • Used in: PVC, home electronics (including televisions and computers), adhesives, upholstery, carpet backings, rubber, plastics, paints and varnishes

HBCD (Hexabromocyclododecane)

  • Used in: all polystyrene foam used in building insulation in the US, textile backcoatings for institutional products, present in some audio-visual equipment, refrigerator linings, and wire and cable coatings

HBCD is emerging as a particular chemical of concern because its use in insulation makes it popular among builders to improve energy efficiency in green homes. In addition, HBCD has been found in human breast milk and food.

The bottom line is we don’t understand how flame retardants affect our health, which is why the EPA’s risk assessments will provide crucial information on these pervasive chemicals. (At the Duke SRC, Project 2 is studying how chemicals, including flame retardants, impact thyroid hormones and the Neural and Behavioral Toxicity Assessment Core will be looking at how they affect neuro-development and behavior.) The EPA’s risk assessment will provide a clearer understanding of the human health effects of flame retardants. Stay tuned!