The Effects of the Organic Flame-Retardant 1,2-Dibromo-4-(1,2-dibromoethyl) Cyclohexane (TBECH) on Androgen Signaling in Human Prostate Cancer Cell Lines.

The effects of the organic flame retardant 1,2-Dibromo-4-(1,2-dibromoethyl) cyclohexane (TBECH) on androgen receptor target gene expression were examined in the human LNCaP prostate cancer cell line. While γ-/δ-TBECH alone led to a significant increase in prostate-specific antigen (PSA) mRNA accumulation, both the α-/-TBECH and γ-/δ-TBECH mixtures repressed androgen-inducible PSA mRNA and protein accumulation in human LNCaP cells. Thus, we hypothesize that isomeric mixtures of TBECH may act as partial agonists of the androgen receptor.

Effects of the bioaccumulative polybrominated diphenyl ether flame retardant congener BDE-47 on growth, development, and reproductive success in zebra finches.

This study investigated the effects of the polybrominated diphenyl ether congener, 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) on the growth and development, and subsequent breeding success of exposed zebra finches (Taeniopygia guttata). Using oral dosing procedures and treatments adjusted by weight, we treated newly hatched chicks daily for the first 20-days-post-hatch (dph) with varying treatments of BDE-47 (0, 5, 50, and 500 ng/g bw/day). Weight and tarsal measurements were monitored from hatch to 90 dph, but no differences were observed between treatment groups at any age. Treated females that reached sexual maturity were mated with untreated males; however, again no treatment effects were observed on breeding success. Analysis of tissue samples at 21 dph did indicate that debromination of BDE-47 had occurred resulting in BDE-28 and BDE-17 metabolites.

An assessment of in ovo toxicity of the flame retardant 1,2-dibromo-4-(1,2-dibromoethyl) cyclohexane (TBECH) in the zebra finch.

Embryonic toxicity of a brominated flame retardant, TBECH (1,2-dibromo-4-(1, 2-dibromoethyl) cyclohexane) was investigated using the zebra finch (Taeniopygia guttata) as our model. Using in ovo dosing procedures, we injected the technical TBECH compound, consisting of 50:50 α-/ß-isomers, directly into the yolk of freshly laid eggs at concentrations of 2.3-94 ng/g egg. No significant effects were observed in terms of growth or survival for either pre-hatch embryos or post-hatch chicks. Analysis of tissue samples at various developmental stages suggests that α-/ß-TBECH was metabolized rapidly, and thus is unlikely to cause any direct, long-term effects on the development of zebra finch embryos or offspring.

Bioaccumulation and biomagnification of PBDEs in a terrestrial food chain at an urban landfill.

Biota samples from the Vancouver municipal landfill located in Delta, BC, Canada, have some of the highest polybrominated diphenyl ether (PBDE) levels reported from North America. We followed a population of European starlings (Sturnus vulgaris) breeding in a remediated area in the landfill to identify exposure routes and bioaccumulation of PBDEs in a simple terrestrial food chain. This population was compared to a reference farm site located 40 km east in Glen Valley. We analyzed samples of European starling eggs and nestling livers as well as invertebrate prey species consumed by starlings for PBDE concentrations. We also collected soil samples from starling foraging areas. All samples from the Delta landfill had higher PBDE congener concentrations compared to the Glen Valley reference site and were dominated by BDE-99 and BDE-47. Stable nitrogen (δ N15) and carbon (δ C13) isotope analysis of starling blood samples and provisioned invertebrates revealed that stable δC13 signatures differed between the sites indicating that the diet of starlings in the Delta landfill included a component of human refuse. Biota-soil accumulation factors (BSAFs) > 1 demonstrated that PBDEs were bioaccumulating in soil invertebrates, particularly earthworms, which were readily accessible to foraging starlings in the landfill. Biomagnification factors (BMFs) calculated from foraged food items and starling egg and liver samples were >1, indicating that a diet of soil invertebrates and refuse contributed substantially to the PBDE exposure of local starlings.