Ogawa passive badges were analyzed at the University of Pittsburgh, Department of Geology & Planetary Sciences using water-based extraction and spectrophotometry (Thermo Scientific Evolution 60S UV-Visible Spectrophotometer) for NO2 ppb concentration.
To date, 25 spots have been analyzed (12 from animals treated with 50 ppb As and 13 from controls).
The dichotomous aflatoxin concentration variable was analyzed to compare the odds of exposure to aflatoxin at levels > 20 ppb by market location, maize history, and vendor type.
Over 18 years, 2,291 monthly NO2 samples were collected and analyzed, averaging 24.0 ppb (0.78 69.4 ppb).
Perchlorate has been found at ppb levels in drinking water, whereas concentrations reported in food vary from low ppb concentrations to highs of several ppm.
The ranges for low, medium, and high exposure were 31.46 37.29 ppb, 37.30 38.11 ppb, and 38.12 50.13 ppb, respectively, for children living in New York City; and 33.50 42.57 ppb, 42.58 45.06 ppb, and 45.07 55.19 ppb for children living in other New York State regions.
Chemical compounds analyzed at the ppm and ppb levels require the application of adequate analytical procedures.
Gold, silver and thallium are at ppb levels, while arsenic, antimony and copper range from hundreds to thousands of ppb.
For 2006, the estimated mean ozone reduction is 0.97 ppb at the 75-ppb standard, 2.06 ppb at the 70-ppb standard, and 5.73 ppb at the 60-ppb standard.
The limit of detection for all pesticides analyzed was 0.1 ppb.
