Publications by authors named "Gurusankar Saravanabhavan"

Nationally representative human biomonitoring data on persistent organic pollutants (POPs) including organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs) brominated flame retardants (BFRs) and perfluoroalkyl substances (PFASs) are available through the Canadian Health Measures Survey (CHMS). We have used a systematic approach building on the reference interval concept proposed by the International Federation of Clinical Chemistry and Laboratory Medicine and the International Union of Pure and Applied Chemistry to derive human biomonitoring reference values (RVs) for selected POPs in blood plasma in the general Canadian population. Biomarkers were chosen based on specific selection criteria including their detection in most Canadians (>66% detection rate).

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Human biomonitoring reference values are statistical estimates that indicate the upper margin of background exposure to a given chemical at a given time. Nationally representative human biomonitoring data on 176 chemicals, including several metals and trace elements, are available in Canada from 2007 to 2013 through the Canadian Health Measures Survey (CHMS). In this work, we used a systematic approach based on the reference interval concept proposed by the International Federation of Clinical Chemistry and Laboratory Medicine and the International Union of Pure and Applied Chemistry to derive reference values (RVs) for metals and trace elements.

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Human biomonitoring (HBM) is used to indicate and quantify exposure by measuring environmental chemicals, their metabolites or reaction products in biological specimens. The biomonitoring component of the Canadian Health Measures Survey (CHMS) is the most comprehensive initiative providing general population HBM data in Canada. The CHMS is an ongoing cross-sectional direct measures survey implemented in 2-year cycles.

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We have analyzed the trends in the body-weight-adjusted urinary monoethyl phthalate (MEP) concentrations and the diethyl ethyl phthalate (DEP) daily intake estimates in the general Canadian population (aged 6-49 years) using the Canadian Health Measures Survey 2007-2009 dataset. The creatinine correction approach, as well as the urine volume approach in a simple one compartment model were used to calculate the daily urinary MEP excretion rates and DEP intake rates in individual survey participants. Using multiple regression models, we have estimated least square geometric means (LSGMs) of body-weight-adjusted MEP concentration, daily excretion and intake rates among different age groups and sex.

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Objective: To investigate the influence of phthalate exposure on lung function in the Canadian population.

Methods: We tested the association between 1-second forced expiratory volume (FEVl), forced vital capacity (FVC), and urinary phthalate metabolite levels in a nationally representative sample of 3147, from 6 to 49 years old.

Results: An interquartile increase in mono-n-butyl phthalate was associated with decreases in percent predicted FEV1 of 0.

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Phthalate metabolites are often measured in biomonitoring studies to evaluate a population's exposure to ubiquitous phthalates. During the course of national biomonitoring studies in Canada, we identified an issue with the accuracy of several commercial phthalate metabolite standards that are commonly used in such studies. The validity of the results from these studies was then questioned.

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Human exposure to phthalates occurs through multiple sources and pathways. In the Canadian Health Measures Survey 2007-2009, 11 phthalate metabolites, namely, MMP, MEP, MnBP, MBzP, MCHP, MCPP, MEHP, MEOHP, MEHHP, MnOP, and MiNP were measured in urine samples of 6-49 year old survey respondents (n=3236). The phthalate metabolites biomonitoring data from this nationally-representative Canadian survey are presented here.

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High molecular-weight phthalates, such as diisononyl phthalate (DINP), and diisodecyl phthalate (DIDP), are widely used as plasticizers in the manufacturing of polymers and consumer products. Human biological monitoring studies have employed the metabolites of DINP and DIDP as biomarkers to assess human exposure. In this review, we summarize and analyze publicly available scientific data on chemistry, metabolism, and excretion kinetics, of DINP and DIDP, to identify specific and sensitive metabolites.

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Oxidative stress has been implicated in various pathologies as well as in environmental pollutant-induced negative health outcomes. In this work we have developed an analytical method to measure oxidative stress markers namely m-, o-tyrosine, 3-chlorotyrosine, 3-nitrotyrosine, and the DNA damage marker 8-hydroxy deoxyguanosine in human urine. The method involves the base hydrolysis of the urine sample followed by solid phase extraction of target analytes using a reverse phase polymeric sorbent column prior to the HPLC-EC analysis.

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In recent times, there has been an increased concern over the appearance of human estrogens in marine ecosystem and their effects on the marine habitat. Discharge of raw sewage has been identified as one of the most important sources of human estrogens in the marine environment. Therefore, we have developed a gas chromatography-(ion-trap) mass spectrometry/mass spectrometry method for the analysis of natural estrogens estrone (E1), and 17beta-estradiol (E2) and synthetic estrogens 17alpha-ethynylestradiol (EE2) and diethylstilbestrol (DES) in sewage effluents, seawater and mussels.

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We report an offline multi-dimensional high performance liquid chromatography (HPLC) technique for the group separation and analysis of PAHs in a heavy gas oil fraction (boiling range 287-481 degrees C). Waxes present in the heavy gas oil fraction were precipitated using cold acetone at -20 degrees C. Recovery studies showed that the extract contained 93% (+/-1%; n=3) of the PAHs that were originally present while the wax residue contained only 6% (+/-0.

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