Future Science Issues of BFRs

Future Science Issues of BFRs

Linda S. BirnbaumDirector, Experimental Toxicology Division

NHEERLResearch Triangle Park, NC

Region 2 Science Day/Non-Regulated Pollutants Workshop

NYC – October 25, 2005

Why BFRs?

• Flame retardants save lives

• Many classes of FRs BFRs most cost

effective

• >75 different BFRs Br-BPs, BDEs, CDs,

phenols, phthalates,++

• Global, transboundary problem

• Persistence• Potential for

bioaccumulation• Limited data base

TBBPA

• Extensive Ongoing Studies under “FIRE”

HBCD

• Persistent; Bioaccumulative; Potentially Toxic

• Science Needs Exposure Information Toxicity Studies

HBCD in 30 Canadian Human Milks (ppb lipid)

(Ryan and Patry, 2002)

Mean Median Min Max

6.6 1.3 0 126

PBDEs

• Penta and Octa• No longer produced in US, but

continued use allowed• Persistence and bioaccumulation

-- continuing concern

Penta and Octa Science Questions

• How are the congeners getting into the environment?

• Environmental fate and transport?• Pathways of human exposure

Dust>Diet???• Modes of action for toxic effects

BDE Structures

BDE 100

BDE 47

BDE 99

BDE 153

Commercial Mixture vs. Humans

MediaBDE Congeners (%)

47 99 100 153 154Commercial PentaBDE 37 48 8 4 3

Human Tissue 54 14 8 20 4Hites 2004

WHY THE DIFFERENCE?• Environmental degradation/debromination?• Altered toxicokinetics?

Are most people like mice or rats?

Deca

• High volume product• Worldwide presence• PPM concentrations in sediment• PPB concentrations in biota

Deca Science Questions

• Deca Breakdown Photolytically Microbially Metabolically

• Is Deca (BDE209) itself toxic?• What about Deca Metabolites/

Breakdown Products?

Potential Health Risk of PBDEs

• Margin of exposure for PBDEs appears low

• Additional concerns: Are PBDEs interacting with other

PBTs? Contamination with Brominated

Dioxins/Furans