# B r o m ina t ed Fl a m e

R et ard an t s :

Ass ess i n g De c a BDE D ebrom inat io n

i n t h e E n v

i ro n m e nt

H E A T H ER M

. S T A P L E TON (PhD, M S

, BS)

MAY 2 0 0 6

28 Bou le vard Charlemagn e

1 0 00 B rus sels ( Be lgiu m )

Te l

. : + 3 2 2 23 4 364 0

F a x. : +3 2 2 23 4 3649

info @e nv

- h e alth.org

www .env

- h e alth.orgAbo u t th e Aut h o r

Heat he r Staple to n ’ s expert is e is i n th e fa t e an d

b i o t ra n sf o r m a t i on of orga ni c co nt a mi nan t s i n

aqua t i c sy s t e m s, f

ocus ing on p er s i s te n t o r gan ic

p o l l ut a n t s (

PO P s ), s uch as p o l yc h l ori na te d

b i p he nyl s ( P C Bs ) and po l yb r om in at ed d i p h eny l

ethe rs ( P BD E s ). S h e i s p r es en t ly carry i n g o ut

resea rc h on D e caB DE debro m ina ti o n at Duk e

Un i ver si ty, N i ch ola s Sch o ol Fa c ulty, Envir o n me n tal

S c iences and Policy Div

i si on in her c a p aci t y as an

En v ir on m e n t a l Chemi s t

.

I. Cont ext fro m Eur ope an Pu bl i c Heal th

Al l iance

– En v i ro n m e n t Netw o rk

.

T he draft a ddendum e nv

i r o nm e nt al r i sk as se ss me nt

repo r t f o r d ec a br o m o d ip h en y

l ether ( D ec a B D E)

was dist rib ute d t o the Tech ni cal C o mmi ttee f o r

New and Exi s t

i n g S ub st a n c es (

TC NES) on Augus t

11, 2005 (

T h e addendum can b e f o u nd a t the

Euro pea n INv en to r y of Exi sti ng Co m m ercia l

chemi c a l Sub s t a nce s (EI NECS ),

[h t t p ://ec b.j rc.it /e x i s ti ng- chemical s/])

. T h e

p r evi ous risk as s e ss me n t, a greed i n M ay 2004, had

conc l ude d t h at furt he r inf o rm at io n w as required

b e f o re defi ni tive con cl us io n s co ul d be d rawn on t h e

conc ern s fro m De caBD E t o the e nv i ro nme nt

.

O n e o f the key a r eas i d entif i ed fo r fur th er

cl a r i ficat i o n was th e e x ten t and impo r ta nce o f the

de b r o mi na tio n of DecaB D E in t he envir o n men t

. T he c o nclusi o n in t he d raft addendu m pre pa re d by

t h e UK govern m e nt h i g h l i g h ts t ha t it is s t

i l l no t

p o s s ib l e t o g

ive a reliable asse ss m en t of the o ve r a l l

signi fica nce of d eb r omi na t i o n ba sed on exp er t

judgme n t. Althou g

h t h e c o n cl usi o n s s t at e that the

p ub l is hed data o n de b r o mi na t io n hei g h te ned the

conc ern, it did n o t neces s a ry mean t ha t

de b r o mi na tio n w a s a signif ica nt p a th w a y i n t he

envir o n men t. T hi s view wa s als o e l a b o rat ed in a

TN O repo r t com m i ssi o ned by t h e B r o mi na t e d

S c ience Enviro n me nt Forum 1

, an indus t r y bas e d

ass ocia ti on

.

1 A.O

. H a ns tv ei t MSc

, Dr. C. T

. Bow m er

, D r. A.P

. Frei dig. T N O

N eth erlan ds Or ga ni sat

io n for Ap p lied Scien ti fi c R esear ch

. A r ev ie w o f

the an aer ob ic and abiotic degra da tion of t he flam e r et ar dant

de cabro mod ip h en yl et he r ( CAS # 1 1 63-1 9 -5) in the co n t e xt of an E U

en v ironm en tal ri sk as s essment report

, cus to m er BSEF

– Bromine

Scien c e and E n

v ironm en tal Forum & The Int erna tional O r ganization of

the B rom in e Ch e mi c a

l Indus tr y

. 1 7 August 2 0 05 ( E C B TRA CK I N G

N O

. COM 013 _E N V

_ IN D 0 9 ) T he i n t en t of t h i s overview i s t o provide a s umma ry

o n t he signif

i c an c e and ext en t o f D eca BDE

de b r o mi na ti o n i n the envi ro n men t

. If Dec a B D E i s

a ‘signi fica n t’ pat hway for t h e for ma t i o n of lower

b rom i nat ed co n g ene r s, there are b ot h p o t e nt ial

a d ve rs e en

v iro n me nt al an d health con seque nces

. T he pot en t

ial pers is t en cy a n d bioacc um u la t i o n

p ro pe rt i e s of the lower congene rs mus t be taken

int o c o n s i der at

i o n in t h e risk ass e ss me nt

. M ore ove r, t h er e may b e l e gal i mpli c a ti o n s f o r

p ut t i ng o n the m a r ket indi r ec tly th ro u g h De caB DE

a n d int o the envi r on me n t t h ese lower conge n e r s,

suc h as P e nt a BD E an d O ct BD E, which are a l r eady

res tr ic ted un d er ex isti ng

EU r eg ul a ti on

.

II

. I nt ro du c ti o n

Dec a b r o m od i p h eny

l e t her (B D E 209) i s a multih a l o g e n ated o r ga ni c chemical us ed p ri ma rily a s a

f l ame reta rda nt in a c om m e rci a l mixtu re kn ow n as

Dec a B D E. It ha s been use d as an ad ditive flame

reta rda n t since the late 1 97 0s

, and because it i s well

sui t e d to f

l ame re t a rd in par ticula r p l as t i cs, its

marke t d em a nd has i n cr eas ed signif i ca n tly o ve r the

p a s t f e w d e cades with the incre a si n g use o f plas t i c s

in electric a l g o od s 1

. Co m m ercia l ly p r o d uced

Dec a B D E con sis ts prima ri l y of B DE 20 9 ( < 97 %)

wi t h mino r c o n tr ibu ti on s (0.3 to 3 .0% ) of o c ta

- and

n o n a BD E c onge n er s (or is o

- for ms ), w h i c h are

im p u ri tie s in t h e techn i ca l mixtu re. A p arti c ul a r

co n c ern rega r di n g BDE 209 is the po te nt ial fo r

de g radat i o n via debr o m i n a t io n

. De b ro m i na t i on is a

p roc es s b y w

h i ch bro m in e at oms are s equen t i all y

rem o ve d or cl e a v ed from an org anic com po un d

,

res ul t i ng in a s mall er lower bro m in a t e d mole c ule

whic h i s slightly mo re wat er s o l u b l e. T he se lowe r

b rom i nat ed conge n e r s ha v e the p o te n ti a l to be m o re

p ersi s te n t and m ore bioacc umula tive t h a n t heir

larg e r paren t c he m ical

.

II I

. Envir o n m e nt al L evel s of D ec a BD E

Nume ro u s s t ud i e s h a v e inve s t ig a t ed the prevalen ce

o f polyb ro m i na t e d diphe nyl e t h e r ( P B D E )

co n g e n er s i n the e nv

i ro nme nt 2, 3

.

BD E 209 is a fully br o mi n a t ed PB DE conge n e r

co ntai ni ng ten br om i ne ato m s (See Figure 1)

. A

majo ri ty of envi ro n men t a l s a m p l e s, specifically

Br o min a t e d F l a me R etardants: As s e s s i n g D ecaB D E D e br om i nat io n i n t h e E n

v ir on m e n t 2h um a n a nd b i o l o g i cal sa m ple s

, co n t ai n PB D E

congen er s t ha t are d o m ina te d b y con g en er s w i t h

four t o s ix br om i ne at o ms 4, 5

. P en t a B DE and

O c ta B D E are t

w o a d d itio n al c o mme rcial

b rom i nat e d flame r et a rd a n t m i x t ures cont ain in g

P B DE c o ngen e rs with f

ou r to ei ght b r omi ne at o ms

( s ee Ta b l e 1)

, and are believed to b e the s o ur ce o f

t h es e c o ngene rs in biolog i c a l s am ple s

. However,

de b r o mi na tio n of B D E 209 can n o t be rul ed o ut a s a

sou rce o f th ese lower b r o mi na ted congene rs

.

BD E 209 has b ee n m easure d in hou se dust 6- 8 at

conc en t ra tio ns up t o 10,0 00 pp b

, which could be a

p o t en t ia l pa t h way o f h um an exp o s u re, part i cul arly

for young children. Todd l e r s have a p re d is po s i ti on

t o p ut d i r t

y hands an d toys in t h ei r m o ut h and

inadve rte n tly inge s t larg er a m ou nt s o f h o use dus t

. T hi s predilec ti on ha s been r es po ns ib l e f o r large

case s of le ad pois on i ng in U.S. children, 9- 11 d ue t o

t h e h i gh le ad l e v el s in h o us e dus t

. No studie s h ave

inves tigat ed th e levels of PB D E s i n c hild r en un d er

t h e a g e of 5; h o w e ver

, m o d el in g s t ud i es sug g es t

t o d d le rs are re ce iv

i n g greate r expo sure t o P B D E s

t h an adul t s because of t h e high lev e ls i n hou s e dus t

12

. In s o me ho mes studied, B DE 2 09 c o mp ri se s

90% o f the t o ta l PB D E b urde n, 7 t h e r ef o re, BDE

209 expo sur e co ul d be unique to yo un g children.

Concl us io n

Deb r o min a t

i o n of B DE 209 c a nn o t be rul ed o ut as

a sou rce o f l o w er bro m i n a t ed c o n g en er s.

Dec a B D E i s mai n l y foun d i n dust i n t h e indo o r

envir o n men t i n c lud i n g our hom e s an d c a r s w h i ch

may result i n e lev a ted expo sur e s in childre n. IV

. Ph o t olyt ic D eb r om i n a ti o n of BDE 209

BD E 209 abso rb s s un l i g h t i n t h e UV reg i o n o f t h e

el ec t rom ag ne tic spec t rum tha t reaches the surfa c e of

t h e earth. D ue to th is l ight abso r pt i o n, B D E 209 is

sus c ep t i ble to ph ot o degra da t i on, w h i c h c a n occur

si g n ific an tly t hr oug h debro m ina ti o n. A majori ty of

t h e UV s p ect ru m is b l o c ked by gla s s wi n d o ws an d

does no t reach i n d o o r envir on m e n t s

. H o w e ver

, sub s t ra te s c o n t ai ni n g BDE 20 9 in di r ect sunlig h t d o

rec ei ve UV radiatio n. Several studi e s have

inves tigat ed t he p ho to d e gradat i o n o f BDE 209 t o

de t er mi ne the time i t takes for 50 % of t h e BDE 20 9

mass to degrade (kn o w n a s t he h alf

- l ife). Ha l f

- lives

vary fr om a f

e w minut es up t o se ve ral years

, de p endi ng upo n the s ub st ra te and li g h t source

( T a ble 2). Söders t rö m e t a l

. 13 examined th e

p h o t o ly tic d e co m po si ti o n of B D E 2 09 in s e ver a l

di ff e ren t type s o f subs tr a te s us ing bo th natural

sunli g h t a n d a UV- lamp. Th e i r study d e m o n s t r a ted

t h at B D E 209 d egr a ded ve ry quic kl y in organ i c

solv en t s but was slowe r when adsor b e d to sedimen t

a n d soil s. A hn et a l

. 14 a l s o ob ser ve d longe r half

li v es of B DE 20 9 when adsorb ed on t o sedimen t a nd

mi n er a l s c o mp a red to d i ss olu ti on i n w ater an d

o rg an i c s o l v en t s. The se studie s sugges t that

a d s or p ti o n o f BDE 209 on to s usp ended mat er i al i n

t h e wat e r column d ecrease s the p ho t o d e g r a d a t io n o f

BD E 2 09 in aqua tic e n vi r on m e n ts

. Staplet on 15

exp o s ed B DE 209 s p i k ed house dus t to sunlig h t and

f o u nd t h a t th e ha

l f- lif e w a s a p p r o x i ma t e l

y 2 20 hour s

o f co n t in uo us sunlig h t e x po s u r e, o r a s s u mi ng 10

h o u r s of sunli g ht a day, a p p ro xi ma t e ly 22 days

. H o w e ver

, it i s di ff

i c ul t to a s s es s t he magni tude an d

dur a ti on o f s un l ight that hou se d us t w o ul d be

exp o s ed to i n an average h o me. Mo st wi n d o w s wi l l

b l o ck out UV wavelen g t h s o f light which would

h i n d e r degradat

i on. In con tras t, c a r dus t h as

rec ently be e n foun d to co n t ai n el ev a ted l ev el s o f

BD E 20 9

( h t t p ://www.eco cen t er

. o rg/ rele a s e s/20060111_au t

o t o x i cs .s h tm l

)

, which i s s us cep ti ble t o gr eat er

sunli g h t expo s ure an d i n w

h i c h debr om in a tio n c a n

b e exp e ct e d t o o c cur significa nt l y.

T he d eg r a d ation pr oduc t s of BDE 209 pho t o l ysi s

a r e prima rily lowe r br om i n ated PB DE congene rs

f o r med vi a debr omi n a ti o n. In soi ls, sedime nt and

h o us e d us t

, t h e primar

y congen e r s i de n ti fied a r e

h epta

- , o c t a- and no n a BD E co n g e n er s 13- 15

, a nd ve ry

li t tle d eg r a d es t o congene rs w i t h few er t h an six

b rom i ne ato ms. W h en dis s o l ve d i n water or

Br o min a t e d F l a me R etardants: As s e s s i n g D ecaB D E D e br om i nat io n i n t h e E n

v ir on m e n t 3 O 2

3

4

5 2 '

3 '

4 '

5 ' 6 6 '

Po l y b ro m i n a t ed D i p h e n y l Et h e r ( P B D E)

Br

n n =1 -1 0

Fig u re 1. Stru ctu re o f PBDE m ol e c ul e.o r

gan ic s o l ven ts

, BDE 20 9 degrades qui t e rap i d l y

and le a d s to g re a te r f o r ma t i o n o f the lower

b rom i nat e d conge n e rs, inc l uding tri

- , t e tra

- an d

p e n ta B DE co n g e n e r s

, an d al s o p ol yb r o mi na ted

dibe n z o fu r a n s (P B DF s ) 13, 16, 17

. In the envir o n me n t,

it is expected t h a t B D E 20 9 will be fo u nd pri ma rily

b o un d to solid s in t h e wate r column

, a n d bo u n d to

p a r ticle s in t h e atmo sp h er e. T her e f or e

, de g radat io n

o f B DE 2 0 9 d i ss olved in wat e r (or o rg an ic s o l ven ts )

is no t exp ec t ed to b e o f enviro nme nta l re le van ce

.

Concl usi o n

It i s difficul t t o as se s s t h e degree of BDE 209

pho to ly t i c debr o mi n a t io n i n hou se dus t

, s o i ls a nd

sedime nt s when expo se d t o li g h t. However, i n cars

debro m i n a t

io n c a n be exp e ct e d t o occur m o re

signi fi c an t l

y. Debr om in at

io n i n water is no t

expected to be of

e n vi r o nme n ta l relevance.

V. M ic r o bi al and Reduc t ive D eb r om i n at i o n of

BDE 209

O n e publi s hed study h as i n ve s t iga ted t h e micr o b i al

mediat e d de b ro mi n at

io n of BDE 20 9 under

anaer o bic (n o o xyg e n

) c o ndit io n s. G e reck e et al

. 18

use d mi cro f

lo ra fr om s ew age s ludge to exa m ine the

b a c t er ial m edia t ed d eg rad a tio n of B D E 209. T h eir

result s indicated t h a t d e b rom in at io n o f B DE 2 09

did o cc ur

, leading to t he fo rma ti on o f n o n a- and

o c ta B D E congene r s. Th e obse r ved firs t orde r

de g radatio n rate, 1.0 x 1 0

- 3 d a y - 1

, is equivalent to a

h a lf lif e o f a pp r oxi m ately 690 days

. Ho w ever

, this

de g radatio n r a te w a s a c celerated by t h e us e of

p r i me r s to increa se de g radatio n p o t e nt ial. W i t h ou t

t h e use of prime rs, t he ob se rved degradati o n rate

was 50% lowe r, re sul t i n g in a h al f

- l ife o f

app r oxi ma tely 3.8 years. Th ere f or e

, a n aer ob ic

b a c t er ia can i n i t

i at e de b r o mi na t

io n of B D E 209,

albeit at a slowe r r a te than ph o to ly t i c

de b r o mi na tio n. Gi

ve n th e h y dr o p ho bic natu re of

BD E 209, a n d the large v o l um es t ha t enter w ater

t r ea tm e nt faci l ities

, an a e r o b i c degradat i on may be

im p o r t an t i n sewage sl ud g e digeste rs

. Ho w eve r

, the

t i me tha t B D E 2 0 9 spend s in th e s ew a g e s l udg e

( r e side nce time ) will g

reat l y im p ac t i t ’s ab i li t

y t o

anaer o bically

d e gr a d e

.

Reduc tive d ebr o m i na ti o n of B DE 209 h a s als o b ee n

repo r te d to o cc ur with mi n e r a l cat aly s t s

. Keum and

Li 19 doc um e nted a step wis e de br o mi na t io n p r oce s s using zero

- valent i r on an d sul fi de mine r a l s. Z e rovale n t iro n w as a goo d o x i d an t for d eg rad a t i o n

, res ul t

i ng i n a BDE 209 half- l i fe of ab o u t one d a y

. T he us e of ir o n sulfide a nd sodiu m sul f ide red uc ed

t h e debr o min a t

i o n /degrad a t i on rate t o 2 and 33%

o f the rate obs erve d for z ero

- vale n t i r on. B o t h t he

ir o n an d s ul fid e s resulted i n de b r o mi na tio n d o w n t o

co n g e n er s with two a nd t h ree b r o mi n es

. In all

exp er im en t s, t h e i ni t

i a l rat e o f d eg rad a ti o n wa s rapid

a n d th e n d e creas e d over time as lower br o mi na t e d

co n g e n er s wer e fo rm ed th at appea red to be m ore

sta ble. While t hi s study de mo n st r a tes the po ss i b i li ty

a n d feasi bilit y o f reductive d eb ro m i na t i on b y

mi n er a l s, th is pro c e s s i s unlikely to occur n a tu ral l y

in th e enviro n men t

. P B DE s will h ave a g r eate r

t en d e n cy to b e b ou nd to natural org a nic matte r an d

soil s in the e n vir on m en t b e fo r e bindi ng d i rec t l y t o

t h e mi n eral sur face, w h i ch is necess a ry fo r the

mi n er a l to act

as an oxid a n t

.

Concl us io n

In s ew ag e a naero b i c ba c ter ia can initiat e

debr o mi n a t io n o f BD E 209, a lbe i t at a slower rat e

than p h o to ly tic d eb r o mi na ti on

, but due to the large

volume s of Dec a B D E i n s ew age sludge t h is may be

signi fican t.

VI

. M et a b o lic D e b ro m in at io n

Deb r o min a t

i on o f B DE 209 h as a

l s o been o b ser ved

in la b o ra to r y i

n vivo s t ud i es wi t h fis h and r a t s,

sug g es ti ng it is me t ab o lized. In four sepa ra te

studi es, f

i sh fed f

o o d s p i ke d wi t h

de cab r o m odi ph en yl e t her w ere f o un d t o a c cumul at e

lowe r br om in at ed conge n e r s 20- 23

. T he assi m i l a t i on

a n d debr o mi n a t io n of B D E 209 varied a m o n g t h e

t hre e fis h species examined, which i n cluded r a i n b o w

t rou t, co mm on carp a n d lake tr ou t. Com m o n c a r p

a c cumul at ed no BDE 2 0 9 in their tissue s, b ut t hey

di d accumulate o n e pe n t a

- , t hre e hexa s

- , t w o hep ta sa n d one o cta B DE conge ner t h a t a p pear ed to result

f r o m t h e debro m in a t

i o n of BDE 2 09. In two

se p a rat e and i n d e pen d e nt res e a rc h studie s o n

rainb o w tr out, a c cumul at i on of B D E 209 was

o b s er ved, al t h o ug h th e up ta k e w as l ess t ha n 1% i n

b o t h s t udie s

. However, bo th studie s obse r v ed a n

incre a s e in hexa-

, h e p t a

- , octa

- a n d no na B D E

co n g e n er s o ve r time t ha t c o mp ri s ed a highe r

p er ce nt age of t h e P B D E b o d y burden relative to t h e

BD E 209 b ody burden. On e s t ud y found an

a c cumul at i on of 0.13% of the B D E 209 dose 20

, whil e the sec ond study o b s er ved an uptake of 3.2%

o f t h e B D E 209 d o s e 23

. Lake t r o u t were fo und to

Br o min a t e d F l a me R etardants: As s e s s i n g D ecaB D E D e br om i nat io n i n t h e E n

v ir on m e n t 4accumula t e a p p r o xi m a t ely 5% of th e B D E 209 dose

and de b r o mi na ti o n w a s hyp o t h e sized t o occur.

However

, the diet in this latte r study c o n s i sted of a

cockta i l o f 1 3 BDEs and i t w a s i m po ss ibl e to

cha r a cte rize d eb r omi na tio n of B DE 209.

S t ap l et o n et al

., 23 r e cen t

l y conducted several i

n v i tr o

exp e rim en t s us ing f

i sh liver m icr o s ome s to

cha r a cte rize me t ab o l ic b i o t ra ns fo rm a t i o n of B DE

209

. Mic r o s o m e s are cel l frac ti on s whic h cont ain

act i ve enzyme s fro m f

i s h tha t typ i cal l

y metab o l ize

endoge nou s comp o un ds (i.e. n at ur a l h orm o n es )

. Using c a r p an d rainb ow tr out l iver mi cr os o me s,

S t ap l et o n fou n d t h a t a s much as 6 5% of B D E 20 9

was d ebr o mi na t e d i n a twenty fou r h o u r p er iod.

Carp m i cro so m e s rapid l

y debr o min a t e d as much a s

30% of t he BD E 209 mas s to fo r m BD E 155 a nd

BD E 154 (hexa B DE s ). In con tra s t

, r a i n b o w trou t

de b r o mi na ted on l

y 22% of the BDE 209 m a ss

p r i ma rily t o oct a

- and n o n aB D E con g e ne r s. T h i s study d em on s t ra t e s that there are spe c ies specif ic

dif f e ren ce s in t h e b i o t ra ns fo rm a t i o n / deb r o m in a t

i o n

cap a c i t y of f is h, a n d pos s ibly

, ot he r org a nis ms

. S t ap l et o n h yp ot he s i z es t h a t t hy r oid h o rm o ne

enzy m e s a r e res p on s ib le for t h is o b se rved

de b r o mi na tio n, which i s similar to endoge nou s

meta b oli sm of t h y r o i d h or mo ne s.

In r a ts, meta b oli sm o f B DE 2 09 appea r s to occur

t hr ough diffe ren t mec h a ni sm s. T w o stud i e s have

examined the upt a k e of B D E 2 09 in r a t s a nd bo th

iden t i fied h yd ro xyl

- a nd met ho xyB D E conge ne r s i n

t i ssu e s and p l a s ma and o n l y trace levels of

n o na B D E c o ngene r s. T hi s s ugg e st s that rat s may

initial l y debr om in a te BDE 20 9, b ut t he n ot he r

meta b olic p at

h w ays beco me m o r e domin an t,

result i ng i n t h e fo rma ti on of mo re p o l ar meta bo l i t e s

t h at are l i kel y

t o be excreted.

Concl usi o n

Some fish appea r cap ab l e of d e b r o mi na t in g BDE

209 t h ro ugh m et a boli s m. T he exten t of the

meta bo l i sm varies among fish an d i t i s d iffic ul t t o

determ in e the ext e nt of debro m ina ti o n that w o ul d

occur i n t h e wild.

VII. H um a n Deb r om i n a ti o n Pot en t i a l

In a recen t s t ud y

, T hu res so n e t a l. 24 measu red

P B DE l eve l s in worke rs occupati o nally expo se d to BD E 209

. An aly s i s of thei r ser um id e n t i f ied sev e ral

h epta

- an d octa

- BD E conge n e rs th a t were no t

p rese n t in the d ec a B DE com me rcial mixtu re n or i n

t h e refere nc e g rou p s. T h e co nge ner pat te r n

o b s er ved in th e se w o r kers was v ery si m i l a r to the

co n g e n er pa t te r n obse r

v ed i n the rai n bow t r out by

S t ap l et o n et a l

. 23

. A foll ow up study e x amined the

BD E c o n ce nt ra ti on s in t he s e worke r s when they

h a d taken a vacat

i on an d reduced thei r exposu r e to

BD E 20 9 24

. T hi s study f o u nd t h a t w h i l e B DE 2 09

co n c en t ra ti o ns d e c reased in these w o r kers w ith a

h a l f lif e of ap p r oxi mat ely 15 days

, conce n t ra t i on s o f

t h e h ep t a- and octa B D E co n g en er s increa s e d,

sug g es ti ng that d ebr o m ina t i on of BDE 2 09 w as

o cc ur ri ng i n h um a n s.

M ore studi es a r e needed to deter mi ne if B D E 20 9

de b r o mi na ti o n d o e s o c cur in human tis sue s.

Ex p o sur e to BDE 2 0 9 i s sug g es te d to b e g reate r fo r

yo un g children relative to adults, d ue to t h e higher

le ve ls p rese n t i n h o us e dust and thu s, may n ee d t o

b e inves tiga ted fur th e r.

Concl us io n

Studies sugges t th at DecaB DE de b ro mi n at e s in

huma ns h owe ver, more s t ud i e s are needed to

con fi r m thi s an al

ys is.

VI I I

. Su m m ar y

Tab le 1 co m p a r es t he P BDE c o ngen e rs th a t are

p rese n t in the c o mme rcia l m i xtur es to the c o nge ne rs

t h at h a v e be e n id e ntif

i e d as p r oduc ts o f B DE 209

de b r o mi na ti o n. A s e vi d en t in t h e table, all t h e

co n g e n er s pre sen t i n t h e c om m e rci a l pr o d uct s also

can be fo rm ed vi a de b r o mi na tio n o f Dec aB DE. Of

p a r t i c ula r c o nce r n in h um a n and en v ir o n m en tal

sam ple s is t h e accum ul a t io n of lower bro m i na t e d

co n g e n er s (

i .e. t e tr a

- , p enta

- an d hexa B DE s ). Ba sed

o n t he curre nt da t a avai l a ble

, t h e poten tia l fo r

si g n ific an t f

orm at io n o f the se co nge n e r s in t he

en v ir on me n t due t o debro m in a t i o n i s low. Th e o nly

studi es d emo n s t ra ti ng fo rm at io n /p r od uctio n o f

t h es e co nge n er s fr om d eb ro m ina ti on occur r e d when

BD E 2 09 was dissol ved in organi c s o l ve n t s and

exp o s ed to sunligh t an d / or UV s o u r ce s, which i s

n o t enviro n m en tal l y relevant. Ad d i t i o n al l y,

red uc t i ve d eb ro mi na ti on catalyzed by iro n and iron

sul fi de s a l s o can lead to the se congen e r s. Howeve r,

t h e l ik el i h o od of B DE 2 09 being directly bou nd t o

Br o min a t e d F l a me R etardants: As s e s s i n g D ecaB D E D e br om i nat io n i n t h e E n

v ir on m e n t 5t h es e t ypes of m i n er a l sur face s i n the e n vi r on m e n t i s

als o l o w

.

In con t ra st

, the f

o rma ti o n o f hexa BD E c o n g en er s

( e .g. BDE 1 53, BDE 15 4 a n d B D E 15 5) f ro m

de b r o mi na tio n o f D ec a B DE has m o r e re a l i st ic

p ro ba b i li t i e s. M eta b o l

i c d eb r omi na t

io n r e sul ted i n

t h e fo rma t

io n o f several h e x a B DE conge ne rs

, incl ud ing BDE 1 54, i n s ev er a l fish species 20, 21, 23

. In

t h es e studies, less than 1% o f th e B D E 2 09

exp o s ur e d eb r omi na ted t o t h e h exa B DE con g e n e rs

, b ut as much as 2 % de b r o mi na te d i n t o h e pt a

- , o cta

and no na B DE c onge n er s

. In t h e pas t y e ar, a few

studie s have documen te d a s h i f t in t he P B DE

congen er patte rn s in h uma n t i ss ues

. In mo s t

studie s, BDE 4 7 (t e t ra B D E ) was th e larges t

con t ri but or to the PB DE b o d y burde n ; however

rec e n t s t ud ie s sugges t s so me p op ul a t i on s ha v e a

P B DE body burden domi na ted by BDE 153, a

h e x a B D E 25, 26

. T h e re a so n fo r t h i s is unkno wn b ut

could be re l a t e d to d eb r omi na t i o n of B DE 20 9

,

exp o s ur e t o diffe re nt P B DE c o mm er cial sou rce s, o r

t o l o nge r ha l f

- l ives for BDE 1 53 re l ative to BDE

47.

P h o t o l y i tic debr om in at

io n o f D ec a BDE i n d us t

, soil s and s e di m en t s also l eads t o t h e for m at io n o f

se v eral h ep t a-

, o ct a- an d non aB DE con g e ne r s,

whic h i s enviro nme nt ally rel e van t. B ec a u se h o u se,

o ffice and car dus t are e nr i c he d in BDE 2 09, t he

p o t en t ia l for d ebr o m in a t

i on i s high w h e n exposed

t o s un l i g ht

. Cur ren t s t ud i es s ug ge s t tha t ph ot ol y tic

de b r o mi na tio n of B D E 209 l eads to significa nt

accumula t i o n o f he p t a-

, oct a

- and n o n aB D E

congen er s whic h are p e rs is te n t an d p o t e nt ially

b i o a c c u mula tive. Th e re a r e v e ry few studie s which

h a v e i n v es t i g a t e d th e b i o a c cumula ti o n po t e nt ial a nd

envir o n men tal lev e ls o f hep ta- t h r o u gh nona B DE

congen er s, which makes an a sses s me nt o f t h eir fa te

dif f icul t. M ore s t ud ie s are needed to deter mi ne the

le v els o f the se con

g e n e rs i n the envi ro n men t

( p a r ticula rly in se d im e nt and dus t) in ord er to

de t er mi ne if d ebro m i na t i on of BDE 20 9 i s

o c cur ri ng. Concl us io n

T he pot e n t i a l fo r s i gni fi c a n t for m a t i on of B DE 4 7,

BDE 99 a nd B DE 1 0 0 i n t h e en v ir on m e n t d ue to

debr o mi n a t io n is low as t he only study sh owi ng t his

is no t envir on m en t al l

y r ele v a n t. Th e fo rma t

io n of

hexaB D E h as mo re realis ti c pro ba b ility and could

be related to d ebr o m ina t i o n of Deca BDE i n

huma ns. P h o t o l

y i tic d ebr o m ina t i o n o f D eca BDE i n

dust, soils and sedime nt s

, leading to th e for m a t i on

of hep ta-

, o c ta- and n o n aB D E c o ngen er s is

envir o n men t ally relevant; n o t w i t h sta nd in g mo re

resea rc h on t he signif i c a n c e of th e s e l o w er

congene r s fate i n th e envir o n men t

.

Br o min a t e d F l a me R etardants: As s e s s i n g D ecaB D E D e br om i nat io n i n t h e E n

v ir on m e n t 6Tabl e 1. PBDE c ongen e rs id ent i f i ed i n com m e r c ial mix tu r es and i n debr o mi na t i on s tudi es

. Cong e ner id en ti f

ic a ti o ns in t he Pe nt aB DE an d OctaB DE com m e rc ial mix tu r es a re fr o m r e fe r en ce

27

.

S ub s t i t ut io n Co n gen er Pe nt a BDE Oc t aBD E DecaBD E For m e d F r o m

Debro min a t io n R eference

2 ,4,4 ’ -tr i br o m o BDE 28 X X 17

, 19

2 ,2 ’ ,4,4 ’ -te t rab r om o BDE 47 X X 17

, 13

, 19

2 ,2 ’ ,4,5 ’ -te t rab r om o BDE 49 X X 17

2 ,3 ’ ,4,4 ’ -te t rab r om o BDE 66 X X 19

2 ,2 ’ 3 ,4 ,4’- p e n t a br o m o BDE 85 X X 14

, 17

2 ,2 ’ ,4,4 ’,5- penta b r om o BDE 99 X X 17

, 13

, 19

2 ,2 ’ ,4,4 ’,6- penta b r om o BDE 100 X X 17

, 19

2 ,2 ’ ,3,4

, 4’,5’- hex ab ro

m o BDE 138 X X 17

, 19

2 ,2 ’ ,4,4 ’,5, 5’- hex ab ro

m o BDE 153 X X 17

, 13

, 19

2 ,2 ’ ,4,4 ’,5, 6’- hex ab ro

m o BDE 154 X X 17

, 13

, 19

, 21, 23

2 ,2 ’ ,4,4 ’,6, 6’- hex ab ro

m o BDE 155 X X 21, 23

2 ,2 ’ ,3,4

, 4’,5’,6-

h e p t a br om o BDE 183 X X X 14

, 17

, 13

, 19

2 ,2 ’ ,3,4

, 4’,6 ,6’- h e p t a br

o m o BDE 184 X 23

2 ,2 ’ ,3,3 ’,4, 4’,5 ,6’- o ctab

ro m o BDE 196 X X 14

, 17

, 18

2 ,2 ’ ,3,3 ’,4, 4’,6 ,6’- o ctab

ro m o BDE 197 X X 14

, 17

, 18

2 ,2 ’ ,3,3 ’,4, 5’,6 ,6’- o ctab

ro m o BDE 201 X 23

2 ,2 ’ ,3,3 ’,5, 5’,6 ,6’- o ctab

ro m o BDE 202 X 23

2 ,2 ’ ,3,3 ’,4, 5 ,5’,6-

oct a br o mo BDE 203 X X X 18

2 ,2 ’ ,3,3 ’,4, 4’,5 ,5’,6-

n ona br om o BDE 206 X X X 14

, 17

, 13

2 ,2 ’ ,3,3 ’,4, 4’,5 ,6 ,6’- no n

abr om o BDE 207 X X X 14

, 17

, 13

, 18

2 ,2 ’ ,3,3 ’,4, 5 ,5’,6 ,6’- no n

abr om o BDE 208 X X X 14

, 17

, 13

, 18

2 ,2 ’ ,3,3 ’,4, 4’,5 ,5’,6 ,6’- d

eca b ro m o BDE 209 X X

Br o min a t e d F l a me R etardants: As s e s s i n g D ecaB D E D e br om i nat io n i n t h e E n

v ir on m e n t 7Tabl e 2. P h o tol yt i c ha l f- lives of

BDE 209 unde r vari o us c on di t i on s

.

Lig h t S ourc e S ubst r a te H a lf L ife (Re fere nce )

UV lamp O r

gan ic S olv en t <0 .2 5 H 13 ; UV lamp S i lica Gel <0 .2 5 H 13 ; UV lamp S a nd 12 H 13 ; UV lamp S e di m en t 40- 60 H 13 ; 15 0 D 14 ; UV lamp S o i l 150 -200 H 13

UV lamp M e t ha no l / wa te r 0.5 H 16

UV lamp M i n erals 36 D – 3.9 Y 14

S un l i ght Hydr ated o n Quar tz 35 H 28 ;

S un l i ght Hydr ated with Humic s o n Q ua rtz 70 H 28

S un l i ght Humic Acid Coated S an d 435 H 28

S un l i ght Hexa n e <0 .2 5 H 17

S un l i ght M i n erals 261 -990 D 14

S un l i ght S a nd 13- 37 H 13

S un l i ght S e di m en t 30- 80 H 13

S un l i ght Hous e Dus t 220 H 15

H- H our s; D- D a y s; Y- Years

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v ir on m e n t 9