PBDEs may pass PCBs as biggest chemical threat
Dumb headline (unless you’re a Fantastic Four fan), but a serious subject. A new chemical analysis, being released today by California EPA scientists at an international scientific conference in Toronto, shows that 30 percent of Northwest moms tested had higher levels of the toxic flame retardants PBDEs in their bodies than of well-known chemical threats PCBs. This study is a follow-up to the PBDE study of Northwest women Northwest Environment Watch did last year.
The study provides pretty unambiguous evidence that PBDEs have emerged as a major toxic menace. And it suggests that, if recent trends continue, PBDEs could soon overtake PCBs as the most dominant "organohalogen" pollutant in people’s bodies.
And an interesting — and probably significant — side note to the study was that there was no correlation between PCB and PBDE levels. This suggests that the two classes of compounds may get into people’s bodies through different pathways. At this point, the principle source of PCB contamination in people is food, particularly fish. For PBDEs, nobody is sure; but a recent exposure modeling study from Canada suggests that ordinary housedust, containing minute quantities of PBDEs sloughed off from furniture and the like, may be the principle route of exposure in people. (More here.)
Some context is in order. PBDEs are fire retardants that are added to furniture foams, industrial fabrics, consumer electronics, and a number of other products. They’re pretty good at preventing fires. But in recent years, scientists have noticed an alarming rise in the concentration of PBDEs in peoples bodies — in their blood, in fatty tissues, and in breast milk alike. Concentrations of the compounds appeared to be doubling every two to five years. Ecologists have found similar rises in marine sediments and wildlife. As it turns out, PBDEs didn’t stay put in consumer products; minute quantities would leach out into the environment and ultimately wind up sequestered in living things, including people.
At the same time that this rapid rise was detected, new evidence was uncovered that PBDEs may have similar health effects as their close chemical cousins, the PCBs. Tests on laboratory animals showed that a dose of PBDEs during a critical phase of early development could cause memory deficitis and behavioral aberrations — effects very similar to those caused by PCBs. The two chemicals may actually work together, either additively or synergistically, to cause harm.
Last year, Northwest Environment Watch commissioned an analysis of 40 breastmilk samples from Northwest moms, 10 each from Washington, Oregon, BC, and Montana. The study found that the moms had among the highest median PBDE levels on record. (Yoiks!)
The problem–and I can’t emphasize this enough–isn’t breastmilk per se; we tested breastmilk just because it was the most convenient way to get a biological sample that’s high in fat, since PBDEs adhere to fat. As far as I know, every epidemiological study that has looked at the issue has concluded that, except in extremely rare cases of PCB poisoning, breastfeeding is by far the best and healthiest choice for infants. The major risk of PCBs appears to be during fetal development; and the benefits of breastfeeding may actually mitigate the potential harms caused by PCB or PBDE exposure in utero. So, seriously, if you’re a nursing mom, keep breastfeeding. Please. Really.
The bottom line of this study is that, even though PCB levels are still higher than PBDE levels, we may soon be approaching a point at which PBDEs are more of a concern than PCBs. And from this I draw 3 lessons. First, we should be paying close attention to PBDE levels in the coming years, to see whether PBDE levels continue to rise in people. Second, we should be looking at ways of removing PBDE-laden products from people’s homes.
And third, we need to learn our lesson about the risks posed by untested chemicals. In retrospect, it should have been obvious that PBDEs posed some risk — their chemical structure is very similar to that of PCBs, dioxin and DDT. So that alone should have triggered some elementary testing requirements before the compounds were used widely commerce. But it didn’t. At some point, we’ve got to learn the lesson, and take steps to make sure this sort of chemical fiasco — releasing potentially harzardous compounds without adequate testing — doesn’t keep happening again and again and again.
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