Inside the EWG-Duke study
NO ESCAPE: : Inside the EWG-Duke study
Inside the EWG-Duke study
After PBDEs went off the market, the chemical fire retardant industry moved toward alternatives such as chlorinated and non-chlorinated organophosphates and brominated phthalate compounds. Exposure to these chemicals had not been studied in children.
To explore this important question, scientists at EWG and Duke University partnered with a pediatric clinic in New Jersey to collect paired urine samples from mothers and children to compare the levels of six alternative fire retardant metabolites. The children were between the ages of one and five, and in some cases we collected urine from more than one child in a household. The samples were collected between August of last year and January of this year.
In all, EWG and Duke tested the urine of 26 children and 22 mothers for six fire retardant metabolites:
- BDCIPP, also called bis(1,3-dichloro-2-propyl)phosphate. This is the principle metabolite formed when the body breaks down an organophosphate fire retardant called tris(1,3-dichloro-2-propyl)phosphate, or TDCIPP. This compound, a member of a family of fire retardant compounds called “chlorinated alkyl phosphates,” was the most frequently detected chemical of this type in one study that tested couches and another that tested baby products (Stapleton 2011; Stapleton 2012b).
- BCIPP, also called bis(1-chloro-2-propyl)phosphate. Its parent compound, tris(1-chloro-2-propyl)phosphate, or TCIPP, was detected in baby products but in lower average concentrations than TDCIPP (Stapleton 2011). Like TDCIPP, TCIPP is a member of the chlorinated alkyl phosphate family.
- DPhP, also called diphenyl phosphate. This metabolite forms when the body breaks down an organophosphorous fire retardant called triphenyl phosphate, or TPhP. TPhP is a component of Firemaster® 550 and is also found in plastics, rubbers, lubricants, nail polish and photographic film. Firemaster® 550 chemicals are the second most frequently detected flame retardant compounds in couches purchased after 2005 and baby products.
- tb-DPhP and ip-DPhP are organophosphate metabolites similar in structure to DPhP. They are the breakdown products of t-butyl triphenyl phosphate, or tb-TPhP, and isopropyl triphenyl phosphate, or ip-TPhP. Firemaster® 550 contains ip-TPhP. A fire retardant called Phosphlex 71B, used in polyurethane foam, contains tb-TPhP.
- TBBA, or tetrabromobenzoic acid, is a metabolite of 2-ethylhexyl-2,3,4,5-tetrabromobenzoate, or EH-TBB. EH-TBB is a brominated compound and component of Firemaster® 550 and Firemaster® 600.
What we found
Four of six of these metabolites were found in children in higher concentrations than adults. BDCIPP, DPhP and ip-DPhP were detected in 100 percent, 98 percent and 96 percent of the test volunteers respectively. Overall, children had higher urinary levels of BDCIPP, DPhP, ip-DPhP and TBBA than their mothers.
Strikingly, the average level of BDCIPP in children one to five years old was 4.9 times that of the average in their mothers, and the average level of DPhP in children was nearly three times that of their mothers. TBBA was detected at a much higher frequency in children’s samples than in those of their mothers. Table 1 shows summary results for all metabolites.
Table 1. Detection frequency and average levels of fire retardant metabolites in mothers and children
|Mothers (n=22)||Children (n=26)*|
|Metabolite||Detection Frequency||Average Level||Range||Detection Frequency||Average Level||Range|
BCIPP, BDCIPP, DPhP, ip-DPhP and tb-DPhP concentrations are in ng/ml (parts per billion)
TBBA concentrations are in pg/ml (parts per trillion)
ND = not detectable
NA = not available (detection frequency was too low to perform a calculation)
*For TBBA analysis n=23 due to insufficient volume in three samples
Notably, BDCIPP levels in adults were two to six times greater than levels reported in previous studies that measured this metabolite in urine collected between 2009 and 2012 (Carignan 2013; Cooper 2011; Hoffman 2014). The higher concentrations in urine samples collected by EWG and Duke in 2013 and 2014 might reflect the increasing use of this compound. Since the EWG-Duke study was the first to analyze BDCIPP in children, there was no basis for comparison to earlier studies.