Temporal variability in urinary concentrations of perchlorate, nitrate, thiocyanate and iodide among children

Department of Preventive Medicine, Mount Sinai School of Medicine, New York, New York 10029, USA.
Journal of Exposure Science and Environmental Epidemiology (Impact Factor: 3.19). 12/2011; 22(2):212-8. DOI: 10.1038/jes.2011.44
Source: PubMed


Perchlorate, nitrate and thiocyanate are ubiquitous in the environment, and human exposure to these chemicals is accurately measured in urine. Biomarkers of these chemicals represent a person's recent exposure, however, little is known on the temporal variability of the use of a single measurement of these biomarkers. Healthy Hispanic and Black children (6-10-year-old) donated urine samples over 6 months. To assess temporal variability, we used three statistical methods (n=29; 153 urine samples): intraclass correlation coefficient (ICC), Spearman's correlation coefficient between concentrations measured at different timepoints and surrogate category analysis to assess how well tertile ranking by a single biomarker measurement represented the average concentration over 6 months. The ICC measure of reproducibility was poor (0.10-0.12) for perchlorate, nitrate and iodide; and fair for thiocyanate (0.36). The correlations for each biomarker across multiple sampling times ranged from 0.01-0.57. Surrogate analysis showed consistent results for almost every surrogate tertile. Results demonstrate fair temporal reliability in the spot urine concentrations of the three NIS inhibitors and iodide. Surrogate analysis show that single-spot urine samples reliably categorize participant's exposure providing support for the use of a single sample as an exposure measure in epidemiological studies that use relative ranking of exposure.

Download full-text


Available from: Barbara Brenner, May 22, 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: Perchlorate (ClO4−) is ubiquitous in the environment and inhibits the thyroid’s uptake of iodide. Food and tap water are likely sources of environmental exposure to perchlorate. The aim of this study was to identify significant dietary sources of perchlorate using perchlorate measured in urine as an exposure indicator. Sample-weighted, age-stratified linear regression models of National Health and Nutrition Examination Survey (NHANES) 2001–2008 data (n=16,955 participants) characterized the association between urinary perchlorate and the mass consumed in USDA food groups, controlling for urinary creatinine and other potential confounders. Separate models of NHANES 2005–2006 data (n=2841) evaluated the association between urinary perchlorate and perchlorate consumed via residential tap water. Consumption of milk products was associated with statistically significant contributions to urinary perchlorate across all age strata: 2.93 ng ClO4−/ml per kg consumed for children (6–11 years-old (YO)); 1.54 ng ClO4−/ml per kg for adolescents (12–19 YO); and 0.69 ng ClO4−/ml per kg for adults (20–84 YO). Vegetables were a significant contributor for adolescents and adults, whereas fruits and eggs contributed significantly only for adults. Dark-green leafy vegetables contributed the most among all age strata: 30.83 ng ClO4−/ml per kg for adults. Fats, oils, and salad dressings were significant contributors only for children. Three food groups were negatively associated with urinary perchlorate: grain products for children; sugars, sweets, and beverages for adolescents; and home tap water for adults. In a separate model, however, perchlorate consumed via home tap water contributed significantly to adult urinary perchlorate: 2.11E–4 ng ClO4−/ml per ng perchlorate in tap water consumed. In a nationally representative sample of the United States 6–84 YO, diet and tap water contributed significantly to urinary perchlorate, with diet contributing substantially more than tap water.
    Journal of Exposure Science and Environmental Epidemiology 11/2012; 23(2). DOI:10.1038/jes.2012.108 · 3.19 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Among women with urinary iodine concentration <100 μg/l in the 2001-2002 National Health and Nutrition Examination Survey (NHANES), urinary perchlorate was associated with significant changes in thyroid stimulating hormone and total thyroxine (T4). Although perchlorate, nitrate, and thiocyanate all potentially act to inhibit iodide uptake, free T4 was not found to be associated with exposure to these chemicals in the same data. Fetuses of pregnant mothers with iodine deficiency are thought to be a sensitive subpopulation for perchlorate exposure, but the potential associations between free T4 and exposure to these chemicals among pregnant mothers in NHANES 2001-2002 and 2007-2008 have not been specifically evaluated to date. This study investigates the potential associations between urinary perchlorate, nitrate, and thiocyanate and serum free T4 in individuals with low urinary iodine levels and pregnant women. Multivariate regression models of free T4 were conducted and included urinary perchlorate, nitrate, thiocyanate, and covariates known to have an impact on the thyroid (anti-thyroid peroxidase (TPO) antibodies, age, race/ethnicity, body mass index, and hours of fasting). Meta-analyses were also conducted on non-pregnant and on pregnant women from the two survey cycles. Urinary nitrate was associated with serum free T4 in non-pregnant women of NHANES 2001-2002 who had urinary iodine ≥100 μg/l. In the meta-analysis, urinary perchlorate, nitrate, and thiocyanate were significant predictors of serum free T4 in non-pregnant women. No association was found in men and pregnant women. TPO antibodies were significant predictors of free T4 among non-pregnant women only when the models included urinary perchlorate, nitrate, or thiocyanate. Risk assessment for perchlorate exposure should consider co-exposure to nitrate and thiocyanate.Journal of Exposure Science and Environmental Epidemiology advance online publication, 23 October 2013; doi:10.1038/jes.2013.67.
    Journal of Exposure Science and Environmental Epidemiology 10/2013; 24(6). DOI:10.1038/jes.2013.67 · 3.19 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The development and application of ion chromatography (IC) coupled to mass spectrometry (MS) is discussed herein for the quantitative determination of low-order explosives-related ionic species in environmental and forensic sample types. Issues relating to environmental explosives contamination and the need for more confirmatory IC-MS based applications in forensic science are examined. In particular, the compatibility of a range of IC separation modes with MS detection is summarised along with the analytical challenges that have been overcome to facilitate determinations at the ng-μgL(-1) level. Observed trends in coupling IC to inductively coupled plasma and electrospray ionisation mass spectrometry form a particular focus. This review also includes a discussion of the relative performance of reported IC-MS methods in comparison to orthogonal ion separation-based, spectrometric and spectroscopic approaches to confirmatory detection of low-order explosives. Finally, some promising areas for future research are highlighted and discussed with respect to potential IC-MS applications.
    Analytica chimica acta 01/2014; 806C:27-54. DOI:10.1016/j.aca.2013.10.047 · 4.51 Impact Factor
Show more