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PBDE

PCB

Thyroid Hormone
Not needed and highly toxic

Polybrominated diphenyl ether (PBDE) flame-retardants were recently shown to be present at very high levels in the blood and house dust of Californians, possibly because of a unique Californian law that requires furniture to be flame-resistant. These chemicals are garnering much interest as of late because of their potential toxic health effects on humans. What are PBDEs, and why might they be toxic?

There are 209 different PBDE varieties, also called congeners. They are identical in molecular structure except that the number and/or position of bromine atoms in each congener vary. One of these congeners, pentabrominated diphenyl ether (penta), is a mixture containing congeners with four, five, and six bromine atoms. It was used extensively in polyurethane foam.

The manufacture of penta was banned by the European Union in 2003 and by the U.S. in 2004 because of increasing evidence of the congener’s toxicity in humans and other organisms. However, no import restrictions exist on products containing penta. Other countries can manufacture penta, add it to consumer products and sell those products in America.

Penta and other PBDEs accumulate in fatty tissues in animals of all kinds and can be passed from mother to child via breast milk. Even though penta was banned in the U.S, it is still present in homes, animals, humans and the environment because of its prevalence in furniture bought before the ban; its use in imported furniture and its apparent resistance to degradation. Other PBDE varieties such as octa and deca, used in plastic electronics casings such as for televisions, volatilize out of the plastic and into the air. They are banned in several states because they have been shown to cause liver toxicity, disrupt reproductive systems and cause endocrine disruption.

PBDEs sound like bad actors, but once upon a time they were the good guys. They replaced polychlorinated biphenyl (PCB) flame-retardants, which were banned by the United States Congress in 1976. PCBs, like PBDEs, are incredibly persistent: 30 years after the ban, PCBs are still found ubiquitously in mammals, human blood and umbilical cords, fish, birds, air, soil, lakes, rivers, house dust, sewage and wastewater sludge.

PCBs were used in coolants, insulating plasticizers, paints, cements, electrical wiring PVC coating, electronic components and pesticide extenders as well as in flame-retardants. Some industrial manufacturing areas are extremely contaminated with PCBs, such as the Hudson River, where fishing has been banned since 1976 due to the high levels of PCBs found in the river and fish. PCBs are considered especially deleterious because when burned, they react with oxygen and turn into the very toxic dioxin. PCBs are carcinogenic, decrease bone density in humans, increase behavioral and reflex problems in rats and decrease immune function in mice.

The basic structure of PCBs is similar to that of PBDEs. This is concerning because structurally similar molecules often have similar functions or modes of action in the human body. Both chemicals are also structurally similar to thyroid hormone, and animal studies have shown that PBDEs does in fact alter thyroid homeostasis.

PBDE flame-retardants look similarly to a known, banned toxin. They accumulate in humans and other animals, resist degradation, and exert toxic effects. The question remains, do they reduce the incidence of fire-related deaths?

A 2006 report by J. R. Hall, Jr. for the National Fire Protection Association shows from 1980 to 1999 states not requiring fire-retardants in furniture experienced the same decline in fire-related deaths that California did; flame-retardants have not displayed a measurable effect on the reduction of house fires. Arleme Blum, a Chemist from the University of California, Berkeley who researches extensively about flame-retardants, points out in a 2006 op-ed article for The New York Times, “most fatal furniture fires are caused by cigarettes, which typically smolder for half an hour after being put down.” 

Recent legislation at the state level in many states across the nation mandates the manufacture of fire-safe cigarettes, which go out when set down due to “speed bumps” of thickened cigarette paper. Smoking materials such as cigarettes are the primary cause of fire deaths in the United States. If that threat is reduced, what use are toxic chemicals?



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RE: One-sided
By The Irish Patient on 10/31/2008 10:44:32 AM , Rating: 3
Good post. The ultimate question is whether the risks outweigh the benefits. If not, watching your children burn to death is not a good alternative to the use of flame retardants. The article doesn't really answer the question for me.

A 2006 report by J. R. Hall, Jr. for the National Fire Protection Association shows from 1980 to 1999 states not requiring fire-retardants in furniture experienced the same decline in fire-related deaths that California did; flame-retardants have not displayed a measurable effect on the reduction of house fires.

The two halves of that sentence don't go together. The author's unstated assumption is that furniture manufacturers maintain two separate production lines. One production line is for furniture destined for California and other states requiring flame retardant. Furniture for all other states comes off of a separate production line where flame retardants aren't used.

More likely, furniture manufacturers maintain one production line, making the California law the de facto standard for the USA. The article admits that fires are in decline everywhere to a significant extent. The implication to me is that the stuff works. The hard, unanswered question is how the risks compare to the benefits.


RE: One-sided
By InvertMe on 10/31/2008 11:01:10 AM , Rating: 4
quote:
If not, watching your children burn to death is not a good alternative to the use of flame retardants.


The smoke will kill your children long before the flames do and most of the flame retardants will just make them burn slower. (that sounds way more morbid than I intend it to)


RE: One-sided
By PedroDaGr8 on 10/31/2008 11:25:49 AM , Rating: 2
Sorry, I thought the same thing at first, but if you look at the hyperlink in the beginning of the article. Zota et al. (1) shows that Californians have drastically higher levels of flame-retardants in their homes than others (for example Cape Cod). By the way, this article, the Zota one, is in an ACS (American Chemical Society) journal which means that it is considered a reputable journal by chemists. I feel the DT article could have made this more clear, but what ever. The polychlrinated biphenyl's are worse than the PDBE's if you ask me. Ph-Br bonds are typically weaker than Ph-Cl bonds and the fact it is an ether means that there are methods of turning it into a phenol as opposed to biphenyls where you are breaking a C-C bond, not nearly as easy as breaking a carbon heteroatom bond.

1)Zota, A. R.; Rudel, R. A.; Morello-Frosch, R. A.; Brody , J. G. Environ. Sci. Technol. 2008 , 42 (21), 8158-8164 (website:http://pubs.acs.org/cgi-bin/abstract.cgi/esthag/20... )

If you have a university IP or live on a university, more than likely your school has an ACS subscription so you should be able to read this article.


RE: One-sided
By TheFace on 11/1/2008 1:12:57 PM , Rating: 2
There is also the possibility that some furniture manufacturers do not sell in the state of California, and thus are not subject to that particular requirement. Also, some manufacturers may have different lines in various parts of the country to cut down on transportation costs and some products go to California or western states and some do not. These are plausible explanations for less amounts of fire retardants in parts of the country.


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