Wide variation in reference values for aluminum levels in children.

BACKGROUND: Some parents are requesting aluminum testing in their children with developmental issues. Although aluminum can be measured in plasma, serum, or urine, there is scant scientific information about normal ranges. We sought to determine the basis for laboratory reference ranges and whether these ranges are applicable to children. METHODS: From texts, published lists, and Internet sources, we obtained the names of 10 clinical laboratories that perform aluminum testing. Contact was made by telephone or e-mail, or Internet sites were viewed to obtain information regarding the establishment of aluminum reference ranges and testing methods in biological samples. Seven laboratories provided supporting literature that was reviewed regarding details of the study populations. RESULTS: For laboratories using the atomic absorption spectrometry method, aluminum reference ranges varied from <5.41 µg/L to <20 µg/L (serum), <7.00 µg/L to 0 to 10 µg/L (plasma) and 5 to 30 µg/L (urine). For those using the inductively coupled plasma mass spectroscopy methodology, ranges varied from 0 to 6 µg/L to <42 µg/L (serum), 0 to 10 µg/L to 0 to 15 µg/L (plasma), and 0 to 7 µg/L to 5 to 30 µg/L (urine). None of the reference ranges are known to be derived from studies of healthy children, but relied instead on small studies of adult populations, adult dialysis patients, workers, or sick children on aluminum-containing parenteral therapy. CONCLUSIONS: Aluminum reference ranges provided by laboratories are widely divergent, may not represent "normal" ranges of a healthy population, especially children, and thus it is difficult to interpret serum or urine aluminum ranges clinically. Further studies of aluminum in children are warranted and should be considered as part of the Centers for Disease Control and Prevention Biomonitoring Project.

An inequality study of ambient nitrogen dioxide and traffic levels near elementary schools in the Tampa area.

Environmental equity has been identified as a challenge and goal of national to global air quality management. Here, relationships between traffic-related air pollution measures and the social demographics of elementary schools are investigated. Ogawa passive samplers were used to measure ambient nitrogen dioxide (NO(2)) levels near 75 randomly selected elementary schools in the county containing Tampa, FL over one week in March 2008. Concentrations were determined using colorimetric reaction using Hach nitrite reagent and photometric detection at 545 nm. NO(2) levels, two metrics of traffic (highest annual average daily traffic count within 500 m and 1000 m), and school enrollment data by demographic subgroup (racial/ethnic and socioeconomic) were then compared. Data were analyzed for distribution statistics, linear correlations, and differences in subgroup category means. Weighted average values of NO(2) and traffic count were also calculated for each subgroup. All measured NO(2) levels were low, with a mean of 2.7 ppbv and range from 0.8 to 4.7 ppbv. Values were largest at sites near downtown. Results from all analyses show comparatively higher potential exposures to measured NO(2) and traffic count for black school children, and lower values for white and Asian or Pacific Islander school children. The economically disadvantaged and Hispanic subgroups were also associated with higher levels of NO(2) and traffic counts, but the relationship was not as strong or robust. Although measured NO(2) levels were low and the differences between groups are small, results suggest disparities by racial/ethnic and economic status in children's exposures to air pollution for the Tampa area.