Use of micro-XANES to speciate chromium in airborne fine particles in the Sacramento Valley.

While particulate matter (PM) in the atmosphere can lead to a wide array of negative health effects, the cause of toxicity is largely unknown. One aspect of PM that likely affects health is the chemical composition, in particular the transition metals within the particles. Chromium is one transition metal of interest due to its two major oxidation states, with Cr(III) being much less toxic compared to Cr(VI). Using microfocused X-ray absorption near edge structure (micro-XANES), we analyzed the Cr speciation in fine particles (diameters < or = 2.5 microm) collected at three sites in the Sacramento Valley of northern California. The microfocused X-ray beam enables us to look at very small areas on the filter with a resolution of typically 5-7 micrometers. With XANES we are able to not only distinguish between Cr(VI) and Cr(III), but also to identify different types of Cr(III) and more reduced Cr species. At all of our sampling sites the main Cr species were Cr(III), with Cr(OH)3 or a Cr-Fe, chromite-like, phase being the dominant species. Cr(VI)-containing particles were found only in the most urban site. All three sites contained some reduced Cr species, either Cr(0) or Cr3C2, although these were minor components. This work demonstrates that micro-XANES can be used as a minimally invasive analytical tool to investigate the composition of ambient PM.

Comparison of N,N'-diarylsquaramides and N,N'-diarylureas as antagonists of the CXCR2 chemokine receptor.

N,N'-diarylsquaramides were prepared and evaluated as antagonists of CXCR2. The compounds were found to be potent and selective antagonists of CXCR2. Significant differences in SAR was observed relative to the previously described N,N'-diarylurea series. As was the case in the N,N'-diarylurea series, placing sulfonamide substituent adjacent to the acidic phenol significantly reduced the clearance in rat pharmacokinetic studies.

A comparison of household lead exposure assessment methods in an old, urban community.

The accurate assessment of lead hazards within the household is critical to the prevention of lead exposure to children living in urban communities. Although dust wipes are currently accepted as the best method of assessing lead hazards, questionnaires and visual inspections are also used. This study evaluates the level of agreement among these three methods of assessment using a sample of 126 women living in old, urban houses. The level of agreement was assessed using the kappa statistic, which adjusts for chance agreement. Overall, the kappa results for both the participant's assessment (questionnaire) and the visual inspector's assessment were low, indicating only slight to moderate agreement with the dust lead wipe levels. Kappas were higher and more consistent for the visual inspector's assessment than for the participant's assessment. These results indicate that visual inspections and participant questionnaires may provide less accurate information regarding lead hazards within the household than dust wipes. Because lead hazard recognition is important in the prevention of lead exposure in children, our data suggest that emphasis should be placed on the measurement of dust lead levels directly in assessing household lead hazards, possibly by teaching women in high-risk neighborhoods to take dust samples themselves.