Organophosphate Esters in Children and Adolescents in Liuzhou City, China: Concentrations, Exposure Assessment and Predictors

Dermal contact with dust is commonly considered an important pathway of exposure to organophosphate esters (OPEs), but the importance of OPE uptake from diet is unclear. Herein, we used hand wipes to estimate OPE exposure from indoor dust and examined whether urinary OPE metabolite concentrations were influenced by sociodemographic characteristics, OPE amount in hand wipes, and dietary factors. OPEs were measured in urine and hand wipes from 6–18-year old children and adolescents (n=929) in Liuzhou, China. Sociodemographic and dietary factors were obtained from questionnaire. Six OPE metabolites were detected in >70% of the urine samples, and seven OPEs were detected in >50% of the hand wipes. Estimated daily intakes (EDIs) were calculated using urinary OPE metabolites to investigate the total daily intake of OPEs, in which 0.36–10.1% of the total intake was attributed to the exposure from dermal absorption. In multivariate linear regression models, sex, age, and maternal education were significant predictors of urinary OPE metabolite concentrations. Urinary diphenyl phosphate (DPHP) is positively associated with its parent compounds 2-ethylhexyl-diphenyl phosphate (EHDPP) and triphenyl phosphate (TPHP) in hand wipes. High versus low vegetable intake was associated with a 23.7% higher DPHP (95% confidence interval (CI): 0.51%, 52.1%). Barreled water drinking was associated with a 30.4% (95% CI: 11.8%, 52.0%) increase in bis(1-chloro-2-propyl) 1-hydroxy-2-propyl phosphate (BCIPHIPP) compared to tap water drinking. Our results suggested the widespread exposure to OPEs in children and adolescents. In additional to dermal absorption, dietary intake may be an important exposure source of certain OPEs.

Characterization of Chemical and Bacterial Concentrations in Floor Dust Samples in Southeast Texas Households

Indoor dust can be a major source of heavy metals, nutrients, and bacterial contamination in residential environments and may cause serious health problems. The goal of this research is to characterize chemical and bacterial contaminants of indoor, settled house dust in the Houston Metropolitan region. To achieve this, a total of 31 indoor dust samples were collected, along with household survey data, which were subsequently analyzed for elemental and bacterial concentrations. Microscopic and geospatial analysis was conducted to characterize and map potential hotspots of contamination. Interestingly Cd, Cr, Cu, Pb, and Zn concentrations of all 31 indoor dust samples were significantly enriched and exceeded soil background concentrations. Furthermore, As, Cd, Pb, and Zn concentrations in the dust samples were significantly correlated to the enteric bacterial load concentrations. Human health assessment revealed that cancer risk values via ingestion for Cd, Cr, and Ni were greater than the acceptable range. Of our 31 dust sample isolates, three Gram-negative and 16 Gram-positive pathogenic bacteria were identified, capable of causing a wide range of diseases. Our results demonstrate that both chemical and bacterial characterization of indoor dust coupled with spatial mapping is essential to assess and monitor human and ecological health risks.

Comparison of supercritical fluid extraction and thermal desorption methods for analysing organic compounds in house-dust

<p>This study has been focused on the comparison of the application of Thermal Desorption (TD) and Supercritical Fluid Extraction (SFE) methods for the identification and quantification of organic chemicals in house dust samples. To investigate how the results obtained by SFE and TD of house dust compare to one another and whether the SFE has advantages over the TD method, an aliquot of a house dust sample has been subjected to desorption at successively increasing temperatures. The thermal desorption unit used cryo - focusing on capillary tubing and was connected to a GC-MS combination. A quantity of the same house dust sample was extracted, using a method consisting of a two-step SFE with CO2 and CO2 + 5% of methanol, and GC-MS analysis of the eluates. The comparison of the results showed that the SFE method was superior to the TD for analysing indoor dust samples because of the pre-separation and the absence of thermal degradation, particularly for compounds of low volatility. However, TD could be more appropriate for relatively volatile or lower molecular weight range compounds and thermally stable compounds.</p>