A Pilot Biomonitoring Study of Cumulative Phthalates Exposure among Vietnamese American Nail Salon Workers.

Many California nail salon workers are low-income Vietnamese women of reproductive age who use nail products daily that contain androgen-disrupting phthalates, which may increase risk of male reproductive tract abnormalities during pregnancy. Yet, few studies have characterized phthalate exposures among this workforce. To characterize individual metabolites and cumulative phthalates exposure among a potentially vulnerable occupational group of nail salon workers, we collected 17 post-shift urine samples from Vietnamese workers at six San Francisco Bay Area nail salons in 2011, which were analyzed for four primary phthalate metabolites: mono-n-butyl-, mono-isobutyl-, mono(2-Ethylhexyl)-, and monoethyl phthalates (MnBP, MiBP, MEHP, and MEP, respectively; µg/L). Phthalate metabolite concentrations and a potency-weighted sum of parent compound daily intake (Σandrogen-disruptor, µg/kg/day) were compared to 203 Asian Americans from the 2011-2012 National Health and Nutritional Examination Survey (NHANES) using Student's t-test and Wilcoxin signed rank test. Creatinine-corrected MnBP, MiBP, MEHP (µg/g), and cumulative phthalates exposure (Σandrogen-disruptor, µg/kg/day) levels were 2.9 (p < 0.0001), 1.6 (p = 0.015), 2.6 (p < 0.0001), and 2.0 (p < 0.0001) times higher, respectively, in our nail salon worker population compared to NHANES Asian Americans. Levels exceeded the NHANES 95th or 75th percentiles among some workers. This pilot study suggests that nail salon workers are disproportionately exposed to multiple phthalates, a finding that warrants further investigation to assess their potential health significance.

Perinatal triphenyl phosphate exposure accelerates type 2 diabetes onset and increases adipose accumulation in UCD-type 2 diabetes mellitus rats.

Triphenyl phosphate (TPhP) is a flame retardant additive frequently found in consumer products and household dust. We administered 170µg of TPhP in maternal food from gestational day 8.5 to weaning and evaluated metabolic phenotypes of 3.5 month old male and female rats, and weight-matched males up to 6 months, to assess the development of obesity and type 2 diabetes mellitus (T2DM), respectively. Perinatal TPhP exposure increased body and fat mass in 3.5 month old male and female rats, while leptin and cumulative energy intake were elevated in males and females, respectively. Independent of body mass, perinatal TPhP exposure accelerated T2DM onset in males and increased plasma non-esterified- fasting fatty acids. These observations suggest that perinatal exposure to TPhP exacerbates the development of obesity in male and female UCDavis-T2DM rats and accelerates T2DM onset in male UCD-T2DM rats.

Environmental Chemicals in an Urban Population of Pregnant Women and Their Newborns from San Francisco.

Exposures to environmental pollutants in utero may increase the risk of adverse health effects. We measured the concentrations of 59 potentially harmful chemicals in 77 maternal and 65 paired umbilical cord blood samples collected in San Francisco during 2010-2011, including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), hydroxylated PBDEs (OH-PBDEs), and perfluorinated compounds (PFCs) in serum and metals in whole blood. Consistent with previous studies, we found evidence that concentrations of mercury (Hg) and lower-brominated PBDEs were often higher in umbilical cord blood or serum than in maternal samples (median cord:maternal ratio > 1), while for most PFCs and lead (Pb), concentrations in cord blood or serum were generally equal to or lower than their maternal pair (median cord:maternal ratio ≤ 1). In contrast to the conclusions of a recent review, we found evidence that several PCBs and OCPs were also often higher in cord than maternal serum (median cord:maternal ratio > 1) when concentrations are assessed on a lipid-adjusted basis. Our findings suggest that for many chemicals, fetuses may experience higher exposures than their mothers and highlight the need to characterize potential health risks and inform policies aimed at reducing sources of exposure.

Analytical methodology using ion-pair liquid chromatography-tandem mass spectrometry for the determination of four di-ester metabolites of organophosphate flame retardants in California human urine.

Alkyl- and aryl-esters of phosphoric acid (both halogenated and non-halogenated) are mainly used as flame retardants (FRs), among other applications, in furniture and consumer products and they are collectively known as organophosphate flame retardants (OPFRs). The absorption, biotransformation or elimination of many of these chemicals in humans and their possible health effects are not yet well known. A major reason for the limited information is the nature of these compounds, which causes several technical difficulties in their isolation and sensitive determination. A novel analytical liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the accurate and sensitive determination of four urinary OPFR metabolites: bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), bis(2-chloroethyl) phosphate (BCEP), bis(1-chloro-2-propyl) phosphate (BCIPP), and diphenyl phosphate (DPhP), using mixed-mode solid phase extraction and isotope. For the first time all four analytes can be identified in one chromatographic run. An extensive investigation of method development parameters (enzymatic hydrolysis, matrix effects, process efficiency, sources of background interferences, linearity, accuracy, precision, stabilities and limits of detection and quantification) was performed in order to address previously reported method inconsistencies and select a process with the highest accuracy and sensitivity. Chromatographic separation was achieved on a Luna C18 (2) (2.00 mm × 150 mm, 3 µm) with mobile phase 80:20 v/v water: MeOH and MeOH: water 95:5 v/v, both containing 1mM tributylamine and 1mM acetic acid. Limits of detection were 0.025 ng mL(-1) for BDCIPP and BCIPP and 0.1 ng mL(-1) for DPhP and BCEP. Absolute recoveries of all four analytes and their labeled compounds were in the range of 88-107%. The method was tested on 13 adult California urine samples. BCEP was detected at 0.4-15 ng mL(-1) with a geometric mean (GM): 1.9 ng mL(-1); BDCIPP at 0.5-7.3 ng mL(-1), (GM: 2.5 ng mL(-1)) and DPhP at

Fast liquid chromatographic-tandem mass spectrometric method using mixed-mode phase chromatography and solid phase extraction for the determination of 12 mono-hydroxylated brominated diphenyl ethers in human serum.

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) are formed from the oxidative metabolism of polybrominated diphenyl ethers (PBDEs) in humans, rats and mice, but their quantitation in human blood and other matrices with liquid chromatography-mass spectrometric techniques has been a challenge. In this study, a novel analytical method was developed and validated using only 250 µL of human serum for the quantitation of twelve OH-PBDEs, fully chromatographically separated in a 15 min analytical run. This method includes two novel approaches: an enzymatic hydrolysis procedure and a chromatographic separation using a mixed mode chromatography column. The enzymatic hydrolysis (EH) was found critical for 4'-OH-BDE17, which was not detectable without it. For the sample clean up, a solid phase extraction protocol was developed and validated for the extraction of the 12 congeners from human serum. In addition, for the first time baseline resolution of two components was achieved that correspond to a single peak previously identified as 6'-OH-BDE99. The method was validated for linearity, accuracy, precision, matrix effects, limit of quantification, limit of detection, sample stability and overall efficiency. Recoveries (absolute and relative) ranged from 66 to 130% with relative standard deviations <21% for all analytes. Limit of detection and quantitation ranged from 4 to 90 pg mL(-1) and 6-120 pg mL(-1), respectively, with no carry over effects. This method was applied in ten commercially available human serum samples from the general US population. The mean values of the congeners detected in all samples are 4'-OH-BDE17 (34.2 pg mL(-1)), 4-OH-BDE42 (33.9 pg mL(-1)), 5-OH-BDE47 (17.5 pg mL(-1)) and 4'-OH-BDE49 (12.4 pg mL(-1)).

Analysis of PFOA in dosed CD-1 mice. Part 2. Disposition of PFOA in tissues and fluids from pregnant and lactating mice and their pups.

Previous studies in mice with multiple gestational exposures to perfluorooctanoic acid (PFOA) demonstrate numerous dose dependent growth and developmental effects which appeared to worsen if offspring exposed in utero nursed from PFOA-exposed dams. To evaluate the disposition of PFOA in the pregnant and lactating dam and her offspring, time-pregnant CD-1 mice received a single 0, 0.1, 1, or 5mg PFOA/kg BW dose (n=25/dose group) by gavage on gestation day 17. Maternal and pup fluids and tissues were collected over time. Pups exhibited significantly higher serum PFOA concentrations than their respective dams, and their body burden increased after birth until at least postnatal day 8, regardless of dose. The distribution of milk:serum PFOA varied by dose and time, but was typically in excess of 0.20. These data suggest that milk is a substantial PFOA exposure route in mice and should be considered in risk assessment modeling designs for this compound.

Determination of carbofuran, carbaryl and their main metabolites in plasma samples of agricultural populations using gas chromatography-tandem mass spectrometry.

A gas chromatography-tandem mass spectrometric (GC-MS/MS) method has been developed for the determination of carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate), carbaryl (1-naphthyl-N-methylcarbamate) and their main metabolites in human blood plasma. Optimization of the isolation of the compounds from plasma matrix included the precipitation, denaturation and digestion of plasma proteins. Derivatization was achieved by the use of trifluoroacetic acid anhydride and was optimized for temperature, time and volume of derivatization agent. In the proposed method, a mild precipitation technique was applied using beta-mercaptoethanol and ascorbic acid in combination with solid-phase extraction technique using Oasis HLB (Hydrophobic Lipophilic Balance) cartridges for further clean up of samples. Carbamate linkage was not hydrolyzed to its phenol product, but both carbamate phenol and ketones were transformed into trifluoroacetyl derivatives in order to become volatile compounds and were determined using tandem mass spectrometry. The linearity of the method was shown for nine concentrations in the range of 0.50-250 ng mL(-1) in fortified plasma aliquots. Limits of detection (LODs) for all compounds ranged from 0.015-0.151 ng mL(-1). Inter-day and intra-day assays (RSD) for all compounds, at three concentration levels of 2.5, 25 and 100 ng mL(-1) (n=3) in fortified plasma samples were less than 18%. Accuracy (%E (r)) was calculated at three concentration levels, 8, 80 and 160 ng mL(-1) (n=3), and ranged from -12.0 to 15.0%. Matrix effect was evaluated so mean recoveries were calculated for all compounds and ranged from 81-107%. Specificity for the use of this method to biological monitoring studies was achieved including four main metabolites of CF, 1-naphthol and 2-naphthol from the naphthalene metabolism pathways, and both the parent compound of carbofuran and carbaryl. The proposed method was applied to plasma samples of pesticide users.

Gas chromatographic-tandem mass spectrometric method for the quantitation of carbofuran, carbaryl and their main metabolites in applicators' urine.

A new gas chromatographic-tandem mass spectrometric method has been developed and validated for the determination of two N-methylcarbamates, carbofuran and carbaryl and their metabolites in applicators' urine specimens. Mild conditions were used for sample preparation based on enzymic hydrolysis and solid-phase extraction using Oasis HLB sorbent cartridges. Amides, phenols and ketones were first converted to volatile derivatives of trifluoroacetic acid anhydride (TFAA) and afterwards were quantitated using tandem mass spectrometry. Linear calibration equations (1-200 ng mL(-1) urine) were obtained from fortified urine samples for all eight compounds, carbaryl, 1-naphthol, 2-naphthol, and carbofuran, 3-hydroxycarbofuran, 7-phenol, carbofuran-3-keto, 3- hydroxycarbofuranphenol. For all compounds, the limit of detection was lower than 0.1 ng mL(-1). Precision for all compounds, at the concentrations of 1, 10 and 100 ng mL(-1) (n = 5) in-fortified urine samples ranged from 0.7% to 18%. Accuracy was calculated at two concentrations 8 and 80 ng mL(-1) (n = 5) and ranged from -8.4% to 8.2%. Relative recoveries at concentrations of 1, 10 and 100 ng mL(-1), ranged from 71% to 116%. The method was successfully applied to five male applicators and 10 non-applicators (including both smokers and non-smokers).

A minisensor for the rapid screening of atenolol in pharmaceutical preparations based on surface-stabilized bilayer lipid membranes with incorporated DNA.

This work describes an electrochemical technique that is suitable for the rapid and sensitive screening of atenolol based on surface-stabilized bilayer lipid membranes (s-BLMs) composed from egg phosphatidylcholine (PC). The interactions of atenolol with s-BLMs produced electrochemical ion current increases that reproducible appeared within a few seconds after the exposure of the membranes to the drug. The current signal increase was related to the concentration of atenolol in bulk solution in the micromolar range. The present lipid film-based sensor provided fast response (i.e. on the order of a few seconds) to alterations of atenolol concentration (20 to 200 micro M) in electrolyte solution. ssDNA incorporated into s-BLMs can interact with atenolol, and decreased the detection limit of this drug by one order of magnitude. The oligomers used were single stranded deoxyribonucleic acids: thymidylic acid icosanucleotide terminated with a C-16 alkyl chain to assist incorporation into s-BLMs (5'-hexadecyl-deoxythymidylic acid icosanucleotide, dT(20)-C(16)). The electrochemical transduction of the interactions of atenolol with s-BLMs was applied in the determination of these compounds in pharmaceutical preparations by using the present minisensor.

Investigation of interactions of a resorcin[4]arene receptor with bilayer lipid membranes (BLMs) for the electrochemical biosensing of mixtures of dopamine and ephedrine.

The present article investigates the interactions of a resorcin[4]arene receptor with planar bilayer lipid membranes (BLMs) that can be used for the electrochemical detection of dopamine and ephedrine. BLMs were composed of egg phosphatidylcholine and 35% (w/w) dipalmitoyl phosphatidic acid in which the receptor was incorporated. These BLMs modified with the resorcin[4]arene receptor can be used as one-shot sensors for the direct electrochemical sensing of these energizing-stimulating substances. The interactions of these compounds with the lipid membranes were found to be electrochemically transduced in the form of a transient current signal with a duration of seconds, which reproducibly appeared within 8 and 20 s after exposure of the membranes to dopamine and ephedrine, respectively. The response time for BLMs without the receptor for dopamine was about 3 min, whereas no signals were obtained for ephedrine in the absence of the receptor. The mechanism of signal generation was investigated by differential scanning calorimetric studies. These studies revealed that the adsorption of the receptor is through the hydrophobic tails of the receptor, whereas hydrophilic groups of the receptor were directed towards the electrolyte solution enhancing the ion transport through the lipid membranes. The magnitude of the transient current signal was related to the concentration of the stimulating agent in bulk solution in the micromolar range. No interferences from ascorbic acid were noticed because of the use of the negatively charged lipids in membranes. The present technique can be used as one-shot sensor for the detection of these pharmaceutical substances and future research is targeted to the determination of these chemicals in human biofluids such as urine of athletes.