The levels of the brominated flame retardants (BFRs) hexabromocyclododecane (alpha, beta and gammaHBCD diastereoisomers) and tetrabromobisphenol A (TBBPA) have been determined in two studies using LC-MS/MS. The methodology developed was validated in-house and used to analyse UK 2004 Total Diet Study (TDS) samples and shellfish (oysters, mussels and scallops) collected from Scotland. HBCD was detected in most samples; in both studies the alphaHBCD diastereoisomer was generally the most abundant as opposed to the gamma diastereoisomer that tends to dominate in environmental samples and manufactured products. It is reported that selective metabolism or biotransformation of the beta and gamma diastereoisomers may be taking place. TBBPA was not detected in any samples above the limit of detection, which was as low as 0.05 microg kg(-1). This may be because TBBPA, unlike HBCD, is chemically bound to the polymer matrix during manufacture and not readily leached. The UK Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) concluded that the concentrations of HBCD and TBBPA detected in the TDS study did not raise toxicological concerns and, as levels in the shellfish samples were in a similar concentration range, it was concluded that exposure to the BFRs measured is not significant when compared to exposure from the rest of the diet.
The Yir body burden ingested as a constant fraction of dietary calcium in 1.5 yr goSr-goY feeding was analyzed for uptake and retention. Retention times were compared to that for a single intravenous injection of at to = 1.5 yr of age ( t ) . The uptake parameters were compared with skeletal and body growth rates. No significant differences in body weight pattern of 452 beagles were observed between the controls and gOSr-fed dogs. The retention parameters in our singly injected beagles were compared with those for 90Sr inhalation studies;no difference was observed. The average skeletal dose rate bo(t) and the time-integrated dose Do(t) were calculated from the mean body burden as a function of age and skeletal/body weight ratios. The local dose was determined by a combination of thermoluminescent dosimetry and measurement ofgoSr concentration. The local dose rate b(t) was corrected for local bone geometry and local distribution ofwSr activities. The local dose rates and dose were compared to the average skeletal dose and dose rate. The local dose to marrow at the proximal humerus was always overestimated by the average skeletal dose and dose rate. The dose rate fjo(t) overestimated the dose to hematopoietic tissue for the first 5 yr of life partially due to averaging of the higher gOSr concentration in cortical bone with the lower concentration in trabecular bones.The Do(t) overestimated D(1) at the cortical regions for all t . Autoradiographic and local measurement of 90Sr in bone revealed that a uniformly labeled skeleton (constant goSr/g of ash) was obtained in 1.5 yr of feeding. For periods t > to the fast local turnover at the proximal region relative to cortical bone produced "cold spots" and low activity regions of cancellous bone. In contrast, the injected cortical bones showed hot spot areas on a diffuse background.
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