Hexabromocyclododecane and tetrabromobisphenol-A in indoor dust from France, Kazakhstan and Nigeria: Implications for human exposure

Concentrations of hexabromocyclododecane isomers(α-,β-and γ-HBCDs)and tetrabromobisphenol-A(TBBP-A)were measured-for the first time-in indoor dust from homes,offices and cars from France,Kazakhstan and Nigeria.∑HBCDs in French and Kazakhstani house dust(median=1351 and 280 ng g^-1,respectively)were consistent with previous reports from the UK and Romania,respectively.Concentrations of ∑HBCDs in Nigerian domestic dust(median=394 ng g^-1)were substantially higher than those reported from Egyptian homes.In general,concentrations of ∑HBCDs in the studied microenvironments were higher than those of TBBP-A,which may be attributed to the major application of TBBP-A as a reactive flame retardant;rendering its release to dust more difficult.Statistical analysis revealed significantly lower ∑HBCDs in French houses than those found in both offices and cars,while ∑HBCDs in cars from Kazakhstan were higher(P<0.05)than those in homes and offices.Moreover,TBBP-A concentrations in car dust from Nigeria were lower than those found in homes and offices.Exposure estimates revealed higher intake of HBCDs and TBBP-A by toddlers via indoor dust ingestion compared to adults.Combined with their low body weight,this can raise concerns over the potential adverse health effects of such high exposure in toddlers.

Effects of Cu^(2+)and humic acids on degradation and fate of TBBPA in pure culture of Pseudomonas sp.strain CDT

Soil contamination with tetrabromobisphenol A（TBBPA） has caused great concerns;however, the presence of heavy metals and soil organic matter on the biodegradation of TBBPA is still unclear. We isolated Pseudomonas sp. strain CDT, a TBBPA-degrading bacterium, from activated sludge and incubated it with ^（14）C-labeled TBBPA for 87 days in the absence and presence of Cu^（2＋）and humic acids（HA）. TBBPA was degraded to organic-solvent extractable（59.4% ± 2.2%） and non-extractable（25.1% ± 1.3%） metabolites,mineralized to CO_2（4.8% ± 0.8%）, and assimilated into cells（10.6% ± 0.9%） at the end of incubation. When Cu^（2＋）was present, the transformation of extractable metabolites into non-extractable metabolites and mineralization were inhibited, possibly due to the toxicity of Cu^（2＋）to cells. HA significantly inhibited both dissipation and mineralization of TBBPA and altered the fate of TBBPA in the culture by formation of HA-bound residues that amounted to 22.1% ± 3.7% of the transformed TBBPA. The inhibition from HA was attributed to adsorption of TBBPA and formation of bound residues with HA via reaction of reactive metabolites with HA molecules, which decreased bioavailability of TBBPA and metabolites in the culture. When Cu^（2＋）and HA were both present, Cu^（2＋）significantly promoted the HA inhibition on TBBPA dissipation but not on metabolite degradation. The results provide insights into individual and interactive effects of Cu^（2＋）and soil organic matter on the biotransformation of TBBPA and indicate that soil organic matter plays an essential role in determining the fate of organic pollutants in soil and mitigating heavy metal toxicity.