8 research outputs found
Direct Measurement of Perchlorate Exposure Biomarkers in a Highly Exposed Population: A Pilot Study
Exposure to perchlorate is ubiquitous in the United States and has been found to
be widespread in food and drinking water. People living in the lower Colorado
River region may have perchlorate exposure because of perchlorate in ground
water and locally-grown produce. Relatively high doses of perchlorate can
inhibit iodine uptake and impair thyroid function, and thus could impair
neurological development in utero. We examined human exposures to perchlorate in
the Imperial Valley among individuals consuming locally grown produce and
compared perchlorate exposure doses to state and federal reference doses. We
collected 24-hour urine specimen from a convenience sample of 31 individuals and
measured urinary excretion rates of perchlorate, thiocyanate, nitrate, and
iodide. In addition, drinking water and local produce were also sampled for
perchlorate. All but two of the water samples tested negative for perchlorate.
Perchlorate levels in 79 produce samples ranged from non-detect to 1816 ppb.
Estimated perchlorate doses ranged from 0.02 to 0.51 ”g/kg of body
weight/day. Perchlorate dose increased with the number of servings of dairy
products consumed and with estimated perchlorate levels in produce consumed. The
geometric mean perchlorate dose was 70% higher than for the NHANES
reference population. Our sample of 31 Imperial Valley residents had higher
perchlorate dose levels compared with national reference ranges. Although none
of our exposure estimates exceeded the U. S. EPA reference dose, three
participants exceeded the acceptable daily dose as defined by bench mark dose
methods used by the California Office of Environmental Health Hazard
Assessment
Analysis of Perchlorate in Human Urine Using Ion Chromatography and Electrospray Tandem Mass Spectrometry
Gas Chromatography-Tandem Mass Spectrometry Method for Selective Detection of 2-Nitropropane in Mainstream Cigarette Smoke
Although 2-nitropropane is a potentially harmful compound present in cigarette smoke, there are few fully-validated, modern methods to quantitate it in mainstream cigarette smoke. We developed an isotope dilution gas chromatography-tandem mass spectrometry (ID-GC-MS/MS) method for the detection of 2-nitropropane in mainstream cigarette smoke. The vapor fraction of mainstream cigarette smoke was collected in inert polyvinyl fluoride gas sampling bags and extracted with hexanes containing isotopically labeled internal standard, then purified and concentrated via solid-phase extraction using a normal phase silica adsorbent and a 100% dichloromethane eluant. This method is sensitive enough to measure vapor phase 2-nitro-propane concentrations in the nanogram range, with a 19 ng per cigarette method limit of detection. Product variability estimated from the analysis of 15 cigarette products yielded relative standard deviations ranging from 5.4% to 15.7%, and estimates of precision from two quality control products yielded relative standard deviations of 9.49% and 14.9%. Under the Health Canada Intense smoking regimen, 2-nitropropane in machine-generated mainstream smoke from 15 cigarette products ranged from 98.3 to 363 ng per cigarette