Figure 2. Flame Retardants and Phthalates Induce Wide Range of Adipogenic Activity.

Zenbio 3T3-L1 cells were differentiated as described in Methods and assessed for adipocyte differentiation (Nile Red staining of lipid accumulation) and cell proliferation (Hoechst staining) after ten days of differentiation while exposed to various brominated flame retardants (BFRs; A–C), organophosphate flame retardants (PFRs; D–F), and phthalates (G–I) from 0.1 nM to 10 μM in concentration. Percent raw triglyceride accumulation per well relative to maximal response for rosiglitazone (A, D, G), increase (cell proliferation) or decrease (potential cytotoxicity) in DNA content relative to vehicle control (B, E, H), and percent normalized triglyceride accumulation per cell relative to maximal rosiglitazone response (normalized to DNA content) (C, F, I). Data presented as mean ± SEM from three independent experiments.

TBB = 2-ethylhexyl-2,3,4,5-tetrabromobenzoate, TBPH = bis (e-ethyl hexyl)-2,3,4,5-tetrabromophthalate, TDBPIC = tris (2,3-dibromopropyl) isocyanurate, BDE-47 = 2,2′4,4′-tetrabromodiphenyl ether, 6-OH BDE-47 = 6-hydroxide-BDE-47, BDE-99 = 2,2′,4,4′,5-pentabromodiphenyl ether, BDE-209 = decabromodiphenyl ether.

TCIPP = tris (1-chloro-isopropyl) phosphate, TDCIPP = tris (2,4-dichloro-isopropyl) phosphate, TPHP = triphenyl phosphate, TBPP = tris (4-butyl-phenyl) phosphate, TiBP = tri-iso-butyl phosphate, TnBP = tri-n-butyl phosphate, TBOEP = tri-(2-butoxyethyl)-phosphate, TBPDP = tert-butyl-phenyl, diphenyl phosphate, FM500 = Firemaster® 550, ITPs = isopropylated triaryl phosphates.

DEHP = bis (2-ethylhexyl) phthalate, DBP = dibutyl phthalate, DiBP = di-isobutyl phthalate, BBP = benzyl butyl phthalate, DEP = di-ethyl phthalate, DEHT = bis (2-ethylhexyl) terephthalate.

* indicates lowest concentration with significant increase in triglyceride over vehicle control or cell proliferation/cytotoxicity relative to vehicle control, p<0.05, as per linear mixed model in SAS 9.4.