Blood lead levels in the adult Victorian population: results from the Victorian Health Monitor

Abstract Objective : To estimate blood lead levels (BLLs) in the adult Victorian population and compare the distribution of BLLs with the current national reference level to better inform public health prevention and management of lead toxicity. Methods : Population‐based cross‐sectional health measurement survey of 50 randomly selected Census Collection Districts (CDs) throughout Victoria. The Victorian Health Monitor (VHM) was conducted over 12 months from May 2009 to April 2010. One eligible person (aged 18–75 years) from each household selected within each CD was randomly selected to participate. Persons with an intellectual disability and pregnant women were excluded from the sampling frame. BLLs were obtained from 3,622 of the 3,653 (99%) VHM participants. Results : The geometric mean and median BLLs from the adult sample were 0.070 μmol/L (95%CI, 0.068–0.073) and 0.05 μmol/L (range: 0.05 to 1.22 μmol/L), respectively. Elevated BLLs (≥0.483 μmol/L or ≥10 μg/dL) were identified in 19 participants (0.7%; 95%CI, 0.3–1.6). Additionally, 86 participants (1.8%; 95%CI, 1.3–2.4) were identified with BLLs between 0.242 and <0.483 μmol/L (5 to <10 μg/dL). The geometric mean BLL was significantly higher for males, compared with females (0.077 μmol/L vs 0.064 μmol/L; p<0.001). BLLs increased significantly with age for both sexes. Conclusions : The first population estimates of BLLs in Victorian adults indicate the average adult BLL to be well below the current national reference level. However, some groups of the population have BLLs at which adverse effects may occur. Implications : The results provide baseline estimates for future population health surveillance and comparison with studies of at‐risk groups

Rod Photoreceptor Loss in Rho ؊/؊ Mice Reduces Retinal Hypoxia and Hypoxia-Regulated Gene Expression

PURPOSE. This study was conducted to evaluate whether regions of the retinal neuropile become hypoxic during periods of high oxygen consumption and whether depletion of the outer retina reduces hypoxia and related changes in gene expression. METHODS. Retinas from rhodopsin knockout (Rho Ϫ/Ϫ ) mice were evaluated along with those of wild-type (WT) control animals. Retinas were also examined at the end of 12-hour dark or light periods, and a separate group was treated with L-cisdiltiazem at the beginning of a 12-hour dark period. Hypoxia was assessed by deposition of hypoxyprobe (HP) and HPprotein adducts were localized by immunohistochemistry and quantified using ELISA. Also, hypoxia-regulated gene expression and transcriptional activity were assessed alongside vascular density. RESULTS. Hypoxia was observed in the inner nuclear and ganglion cell layers in WT retina and was significantly reduced in Rho Ϫ/Ϫ mice (P Ͻ 0.05). Retinal hypoxia was significantly increased during dark adaptation in WT mice (P Ͻ 0.05), whereas no change was observed in Rho Ϫ/Ϫ or with L-cis-diltiazem-treated WT mice. Hypoxia-inducible factor (HIF)-1␣ DNA-binding and VEGF mRNA expression in Rho Ϫ/Ϫ retina was significantly reduced in unison with outer retinal depletion (P Ͻ 0.05). Retina from the Rho Ϫ/Ϫ mice displayed an extensive intraretinal vascular network after 6 months, although there was evidence that capillary density was depleted in comparison with that in WT retinas. CONCLUSIONS. Relative hypoxia occurs in the inner retina especially during dark adaptation. Photoreceptor loss reduces retinal oxygen usage and hypoxia which corresponds with attenuation of the retinal microvasculature. These studies suggest that in normal physiological conditions and diurnal cycles the adult retina exists in a state of borderline hypoxia, making this tissue particularly susceptible to even subtle reductions in perfusion. (Invest Ophthalmol Vis Sci. 2006;47:5553-5560