Simple solid-phase extraction method for determination of polychlorinated biphenyls and selected organochlorine pesticides in human serum

Pesticides monitoring in biological fluids: Mapping the gaps in analytical strategies

Pesticides play a key-role in the development of the agrifood sector allowing controlling pest growth and, thus, improving the production rates. Pesticides chemical stability is responsible of their persistency in environmental matrices leading to bioaccumulation in animal tissues and hazardous several effects on living organisms. The studies regarding long-term effects of pesticides exposure and their toxicity are still limited to few studies focusing on over-exposed populations, but no extensive dataset is currently available. Pesticides biomonitoring relies mainly on chromatographic techniques coupled with mass spectrometry, whose large-scale application is often limited by feasibility constraints (costs, time, etc.). On the contrary, chemical sensors allow rapid, in-situ screening. Several sensors were designed for the detection of pesticides in environmental matrices, but their application in biological fluids needs to be further explored. Aiming at contributing to the implementation of pesticides biomonitoring methods, we mapped the main gaps between screening and chromatographic methods. Our overview focuses on the recent advances (2016-2021) in analytical methods for the determination of commercial pesticides in human biological fluids and provides guidelines for their application.

Gene expression signatures in PCB-exposed Slovak children in relation to their environmental exposures and socio-physical characteristics

Our previous gene expression studies in a PCB-exposed cohort of young children in Slovakia revealed that early-life exposures to PCBs and other organochlorine compounds were associated with significant alterations across several pathogenetic pathways. The present study was undertaken to further explore the high-throughput qRT-PCR-based gene expression effects by using TaqMan low-density array (TLDA) for selected genes in a sample of 55 children from the cohort. We analyzed the transcriptional changes of 11 genes in relation to PCB and organochlorine pesticide exposure levels (including DDT, DDE, HCH, and HCB), and to BMI and ethnicity in this cohort. The results indicated an overall downregulation of expression of these genes. Maximum downregulation (in fold change) was observed in the ENTPD3 gene, and the minimum level of downregulation was in CYP2D6. As per our multinomial regression model study, downregulation of LEPR gene was significantly directly correlated with all the exposure variables. Downregulation of APC, ARNT, CYP2D6, LEPR, LRP12, and MYC genes was directly correlated with BMI (kg/m²) of the individuals. Gender-specific differences in gene expression were observed in CYP2D6 (p-value 0.0001) and LEPR (p-value 0.028), while downregulation of CYP2D6 (p-value 0.01), LEPR (p-value 0.02), LRP12 (p-value 0.04), and MYC (p-value 0.02) genes was consistently observed in Roma children compared to Caucasians. The investigation of such health disparities must be emphasized in future research, together with interventions to reduce the health consequences of PCB exposures. In this context, we emphasize the importance of biomarker-based approaches to future research on genetic susceptibility to the effects of these compounds.

Application of a pharmacokinetic model in characterizing sources of polychlorinated biphenyl exposure and determining threshold daily intakes for adverse health effects in infants and toddlers

Characterization of PCB exposure sources for vulnerable population groups is essential to minimize the health effects of PCB exposure. At the same time, it is important to consolidate the knowledge on threshold intakes of PCBs for infants and toddlers to prevent health effects. We estimated total PCB concentrations from birth to 2 years of age in children from Slovak and Czech populations, which continue to have high PCB concentrations in breast milk. Using a pharmacokinetic (PK) model, we characterized dominant PCB exposure sources and estimated new threshold estimated daily intakes (TEDI) (above which adverse effects cannot be excluded) for postnatal PCB exposure in infants and toddlers. In the PK model, concentrations of seven indicator PCBs in breast milk and cord blood samples from 291 mother-child pairs from the Slovak birth cohort, and 396 breast milk samples from Czech mothers we used, together with their physiological characteristics and PCB concentrations from other exposure sources (food, dust, air). The estimated total PCB concentrations in children's blood at different ages were compared with threshold PCB concentrations of 500, 700 and 1000 ng·g_lipid^-1 in serum proposed by the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) and the German Environment Agency (UBA), above which possible adverse health effects may be expected. We estimated that up to 20.6% of Slovak children and up to 45.7% of Czech children at two years of age exceeded the threshold value of 700 ng·g_lipid^-1 in blood. Mean TEDIs leading to values of 500 ng·g_lipid^-1 in blood for children up to two years ranged between 110 and 220 ng·kg^-1·bw·day^-1, varying according to breastfeeding duration. Breast milk and prenatal exposure contributed to 71%-85% of PCBs exposure at two years of age. In contrast, the contributions of PCBs from dust and indoor air were negligible.

The Status of Polychlorinated Biphenyls (PCBs) Extract from Zhanjiang Mangrove Sediments and the Effects on Tissue Structure and Inflammatory Cytokines in Zebrafish Liver

Polychlorinated biphenyls (PCBs) are released into the environment from a wide range of sources. The aim of the present study was to investigate the effect of the PCBs extracted from the Zhanjiang mangrove sediments on the immune function of zebrafish. The sediments were collected from 3 mangrove forest points in Zhanjiang (Guangdong Province, China), and the results showed that PCB153 was detected in the sediments of the Guangdong Zhanjiang Mangrove National Nature Reserve (MNNR) and Gaoqiao Mangrove Reserve (GMR), while PCB101, PCB112, PCB155, and PCB198 were detected in the sediments of the Leizhou Peninsula (LP). The zebrafish were exposed to different concentrations of PCBs, i.e., control group, positive control group (Aroclor1254; 10 μg/L), low dose group (LD; 0.6 μg/L), medium-dose group (MD; 3.0 μg/L) and high dose group (HD; 15 μg/L) for 14 days. As compared to the control group, the liver index increased significantly in all PCB treated groups. The liver tissue structure was destroyed in all PCB-treated groups as compared to the control group. In addition, the relative mRNA expression of the target genes (IL-1β, IL-8, and TNF-α) was significantly expressed in each concentration group. Therefore, these findings suggest that exposure of zebrafish to PCBs can destroy the liver histology and increase the liver index and mRNA expression of inflammatory cytokines in a dose and time-dependent manner.

Trace-level analysis of polychlorinated biphenyls, organochlorine pesticides and polycyclic aromatic hydrocarbons in human plasma or serum by dispersive liquid-liquid microextraction and gas chromatography-tandem mass spectrometry

A method to determine 8 polychlorinated biphenyls (PCBs), 23 organochlorine pesticides (OCPs) and 16 polycyclic aromatic hydrocarbons (PAHs) was described using dispersive liquid-liquid microextraction (DLLME) of a small amount of plasma or serum sample and gas chromatography-tandem mass spectrometry (GC-MS/MS). The appropriate selection of the extraction solvent and dispersing solvent contributes to a high extraction yield and a clean extract. To verify the developed method, the interference, linearity of the calibration curve, detection limit, precision and accuracy were evaluated. The calibration curves were linear by 2-3 orders of magnitude with correlation coefficients above 0.997 in all cases. The LODs of PCBs, OCPs and PAHs were measured in the ranges of 0.0006-0.0029, 0.001-0.029 and 0.0002-0.012 ng/ml. The intraday precision achieved by this method was 2.19-10.3% (PCBs), 1.65-14.3% (OCPs) and 0.91-12.8% (PAHs), and the intraday accuracy 1.56-7.37% (PCBs), 2.34-19.6% (OCPs) and 1.49-15.7% (PAHs). The advantage of this method is that the analysis of PCBs, OCPs, and PAHs can be performed in a single chromatographic run, and the low detection limit enables monitoring of target substances in low exposure general public samples, and the analysis procedure is relatively simple and fast.

Pre- and postnatal polychlorinated biphenyl exposure and cognitive and behavioral development at age 45 Months in a cohort of Slovak children

Evidence of associations of pre- and postnatal exposure to polychlorinated biphenyls (PCBs) with cognitive development beyond early childhood is inconsistent. A previous report from this cohort observed adverse associations between early life PCB exposures and infant Bayley scores at age 16 months. The present study examines pre- and postnatal PCB exposures in relation to both behavior and cognitive development at age 45 months. Participants were 472 mother-child pairs residing in an area of eastern Slovakia characterized by environmental contamination with PCBs, which resulted in elevated blood serum concentrations. PCB-153 and PCB-118 concentrations were measured in maternal and in infant 6-, 16-, and 45-month serum samples. At age 45 months, children were administered five subtests of the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III), and mothers completed the Child Behavior Checklist (CBCL). Negative binomial and multiple linear regressions were used to estimate PCB-CBCL and PCB-WPPSI-III subtest score associations, respectively. Pre- and postnatal levels of PCB-153 and PCB-118 were not associated with cognitive performance on the WPPSI-III in this cohort. There was some suggestion that higher postnatal PCB concentrations were associated with more sleep problems and feelings of depression and anxiousness.

Experimental Design of Vortex Assisted Switchable Solvent Homogeneous Liquid-Liquid Microextraction for Simultaneous Determination of Four Pesticides in Wastewater

BACKGROUND

Pesticides are chemicals used mainly to protect plant crops in order to increase their production efficiency and quality.

OBJECTIVE

Switchable-solvent homogeneous liquid-liquid microextraction was optimized using a Box-Behnken experimental design and validated on a gas chromatography mass spectrometry system for the determination of analytes.

METHOD

The significance of independent variables (switchable solvent volume, sodium hydroxide volume, and vortex period) and their interactions were evaluated by analysis of variance at 95% confidence limits (α = 0.05).

RESULTS

The LOD and LOQ ranges of the analytes were found to be 0.42-1.90 µg/L and 1.36-6.33 µg/L, respectively. Percentage recovery results were found to be in the range of 87-113% in spiking experiments.

CONCLUSIONS

A simple, efficient, and accurate analytical method was developed for the simultaneous determination of the selected pesticides. Highlights: Matrix matching was used to enhance quantification accuracy for real samples.

HIGHLIGHTS

Matrix matching was used to enhance quantification accuracy for real samples.

A new proposal for the determination of polychlorinated biphenyls in environmental water by using host-guest adsorption

Polychlorinated biphenyls (PCBs) are ubiquitous environmental pollutants whose wide industrial use has been banned over the years in most countries due to their persistence and bioaccumulation. In fact, the International Agency for Research on Cancer defined them in 2016 as carcinogenic to humans based on sufficient evidence of an increased risk of cancer, being children and pregnant or lactating women the most vulnerable population subgroups. In this work, a new alternative for the determination of polychlorinated biphenyls (PCB28, PCB52, PCB101, PCB138, PCB153, and PCB180) in water samples has been developed by using a cyclodextrin-containing silica microparticulated material as an adsorbent in solid-phase extraction. Gas chromatography coupled to an electron capture detector has been used in the quantification step. The methodology allows quantifying polychlorinated biphenyls at very trace levels, with limits of detection between 0.2 and 1.7 ng L^-1. Other parameters such as the repeatability, with coefficients of variation lower than 11%, were likewise established. To end, real water samples were analyzed, and the results were comparable with those obtained with a reference method. The proposed methodology can be utilized for assessing the presence of these compounds in the environment and can come in handy for evaluation and remediation purposes.

PBDE serum concentration and preschool maturity of children from Slovakia

Polybrominated diphenylethers (PBDEs) are persistent organic pollutants (POPs), they are considered endocrine disruptors and can bioaccumulate in nature, and in living tissue. Human exposure to and the presence of PBDEs in human samples is of concern due to their potential health risks. Young children are one of the most vulnerable populations to PBDE's potential health effects. Ninety-one serum samples of 6-year-old children, residing in a contaminated location, due to former production of polychlorinated biphenyls (PCBs), were analysed to examine children's exposure to PBDEs in Slovakia. Median serum concentrations found for individual PBDE congeners BDE-28⁺³³, -47, -99, -100, -153, -154 and -183 were 0.015, 0.184, 0.079, 0.046, 0.176, 0.014, and 0.097 ng g^-1 lipid weight, respectively. Children's preschool maturity was measured using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III) test. In multivariate analyses BDE-153 serum concentrations were significantly inversely associated with WPPSI-III composite score (p = 0.011, β = -23.6), while adjusting for PCB-153 and sex. Significant negative associations were observed for BDE-153 serum concentrations (p = 0.002, β = -29.8) and WPPSI-III composite score, after controlling for PCB-118 and sex. Negative associations were also observed for BDE-47, BDE-100 and BDE-153, with different individual WPPSI subtest scores, after adjustment with PCB-153 and/or PCB-118 and sex. Serum concentrations of PCB-153 and PCB-118 were not statistically significantly associated with WPPSI-III composite score and individual subtest scores. These findings demonstrate adverse effects of PBDE serum exposure on preschool maturity of children, and PBDEs potentially negative impact on child neuropsychological development.

Comparison of sample preparation approaches and validation of an extraction method for nitrosatable pesticides and metabolites in human serum and urine analyzed by liquid chromatography - Orbital ion trap mass spectrometry

In the acidic environment of the stomach, nitrosatable pesticide residues may react with nitrite to form potentially carcinogenic pesticide-associated N-nitroso compounds (PANOCs). The objective of this study was to develop a method for the analysis of 10 nitrosatable pesticides and breakdown products in human serum and urine. Three sample preparation methods were evaluated for extraction of target analytes from the biomatrices. Deproteinization by methanol for 300-μL aliquots of serum with a final extract volume of 225 μL resulted in excessive ion enhancement of some analytes and suppression of others. Three types of solid-phase extraction cartridges were tested for optimal analyte retention from 200-μL aliquots of serum with a final extract volume of 400 μL; this approach resulted in significant analyte loss for some compounds. The Quick, Easy, Cheap, Effective, Rugged, and Safe approach resulted in a suitable method for extraction of the analytes from each biomatrix. Biofluid samples (500 μL) were spiked to 100 μg L^-1 with analytical standards and extracted using 500 μL of acetonitrile (ACN) with 4% acetic acid (AcOH) for serum and 0.1% AcOH in ACN for urine. For extraction, 200 mg magnesium sulfate (MgSO₄) and 50 mg sodium acetate were added for serum and 200 mg MgSO₄ and 50 mg sodium chloride were added for urine. Final extract volumes for both biomatrices using the QuEChERS method was 400 μL after dilution. Samples were analyzed via ultra-high pressure liquid chromatography/high-resolution accurate mass orbital ion trap mass spectrometry. Mean recoveries for target analytes in serum and urine ranged between 74 and 120% (%RSD < 12) and 96 to 116% (%RSD ≤ 10), respectively. These methods may be used in large-scale biomonitoring studies to analyze PANNs and their parent compounds in human serum and urine.

The spatial distribution of congener-specific human PCB concentrations in a PCB-polluted region

Serum PCB congener concentrations were measured in 602 adults living near a PCB pollution source in eastern Slovakia. We created isoconcentration maps for 21 PCB congeners by geocoding each participant's place of residence and kriging. Concentrations of PCB congeners were inversely associated with the distance of the participants' residence from the source of pollution. Congener-specific risk factors were derived, particularly for PCBs 52 and 153. We observed that the spatial distribution of serum concentrations was influenced by micro-climatic parameters and physicochemical properties of the congeners. PCB congener profiles strongly correlated with that of the PCB commercial product Delor 106, which was manufactured in the region. The isoconcentration maps indicate that the zones with the highest predicted congener concentration have a mean area of approximately 235.75±188.56km² and the mean enrichment of concentration of congeners in serum in these zones is about 5.12±1.36. We estimate that depending on congener approximately 23,457±18,762 individuals with PCB concentrations exceeding health-based guidance values live in these zones.

Environmental Toxins and Male Fertility

PURPOSE OF REVIEW

Global industrialization has increased population exposure to environmental toxins. A global decline in sperm quality over the last few decades raises questions about the adverse impact of environmental toxins on male reproductive health.

RECENT FINDINGS

Multiple animal- and human-based studies on exposure to environmental toxins suggest a negative impact on semen quality, in terms of sperm concentration, motility, and/or morphology. These toxins may exert estrogenic and/or anti-androgenic effects, which in turn alter the hypothalamic-pituitary-gonadal axis (HPGA), induce sperm DNA damage, or cause sperm epigenetic changes. This chapter will discuss the most recent literature about the most common environmental toxins and their impact on spermatogenesis and its consequences on male fertility. Understanding the presence and underlying mechanism of these toxins will help us preserve the integrity of the male reproduction system and formulate better regulations against their indiscriminate use.

PCB exposure and cochlear function at age 6 years

Epidemiological studies have documented adverse associations between exposure to polychlorinated biphenyls (PCBs) and otological outcomes. Previously, we documented decreased distortion product otoacoustic emission (DPOAE) levels in children exposed to PCBs, up to the age of 45 months, amongst a cohort of children in eastern Slovakia. The objective of the present study is to evaluate cochlear dysfunction at 72 months of age in 214 children from this same cohort and to compare the otoacoustic test sensitivity to that of pure tone audiometry (PTA). The association between DPOAE, PTA, and PCBs was estimated by means of multivariate ANOVA (MANOVA) and linear regression models. ROC curves were computed to estimate the DPOAE-test power in children. The DPOAE level at 72 months was related to PCB-153 serum levels. The DPOAE Input/Output function test at mid-frequency (2kHz) has shown instead nonmonotonic dependence on PCB exposure, for the left ears of children, over the whole growth curve. No significant association was found between PTA hearing levels and PCB-153 concentration. High diagnostic power of the DPOAE-test was found in children, similar to that found by the same authors in adults. In conclusions the DPOAE-PCB correlation obtained at 72 months is similar to that at 45 months suggesting a permanent and stable ototoxic effect of the PCB exposure. The lack of statistical significance of the PCB-PTA correlation suggests that DPOAEs are sensitive biomarkers of cochlear damage.

DPOAEs in infants developmentally exposed to PCBs show two differently time spaced exposure sensitive windows

The study aim was to identify the timing of sensitive windows for ototoxicity related to perinatal exposure to PCBs. A total of 351 and 214 children from a birth cohort in eastern Slovakia underwent otoacoustic testing at 45 and 72 months, respectively, and distortion product otoacoustic emissions (DPOAEs) at 11 frequencies were recorded. Cord and child 6-, 16-, 45-, and 72- month blood samples were analyzed for PCB 153 concentration. The PCB 153 concentration-time profiles were approximated with a system model to calculate area under the PCB*time curves (AUCs) for specific time intervals (3 and 6 months for 45 and 72 months data, respectively). DPOAE amplitudes were correlated (Spearman) with cord serum PCB and AUCs, markers of prenatal and postnatal exposure, respectively. Two exposure critical windows were identified in infants, the first related to prenatal and early postnatal and the second to postnatal exposure to PCBs. Our data have shown tonotopicity, sexual dimorphism, and asymmetry in ototoxicity of PCBs.

Demographic, Reproductive, and Dietary Determinants of Perfluorooctane Sulfonic (PFOS) and Perfluorooctanoic Acid (PFOA) Concentrations in Human Colostrum

To determine demographic, reproductive, and maternal dietary factors that predict perfluoroalkyl substance (PFAS) concentrations in breast milk, we measured perfluorooctane sulfonic (PFOS) and perfluorooctanoic acid (PFOA) concentrations, using liquid chromatography-mass spectrometry, in 184 colostrum samples collected from women participating in a cohort study in Eastern Slovakia between 2002 and 2004. During their hospital delivery stay, mothers completed a food frequency questionnaire, and demographic and reproductive data were also collected. PFOS and PFOA predictors were identified by optimizing multiple linear regression models using Akaike's information criterion (AIC). The geometric mean concentration in colostrum was 35.3 pg/mL for PFOS and 32.8 pg/mL for PFOA. In multivariable models, parous women had 40% lower PFOS (95% CI: -56 to -17%) and 40% lower PFOA (95% CI: -54 to -23%) concentrations compared with nulliparous women. Moreover, fresh/frozen fish consumption, longer birth intervals, and Slovak ethnicity were associated with higher PFOS and PFOA concentrations in colostrum. These results will help guide the design of future epidemiologic studies examining milk PFAS concentrations in relation to health end points in children.

A Birth Cohort Study of Maternal and Infant Serum PCB-153 and DDE Concentrations and Responses to Infant Tuberculosis Vaccination

BACKGROUND

Reasons for the highly variable and often poor protection conferred by the Mycobacterium bovis bacille Calmette-Guérin (BCG) vaccine are multifaceted and poorly understood.

OBJECTIVES

We aimed to determine whether early-life exposure to PCBs (polychlorinated biphenyls) and DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] reduces 6-month infant BCG vaccine response.

METHODS

Data came from families participating in a prospective birth cohort in eastern Slovakia. At birth, maternal and cord blood were collected for chemical analyses, and infants were immunized with BCG. Blood was collected from infants for chemical analyses and to determine 6-month BCG-specific immunoglobulin (Ig) G and IgA levels. Multivariable linear regression models were fit to examine chemical-BCG associations among approximately 500 mother-infant pairs, with adjustment for confounders.

RESULTS

The median 6-month infant concentration of the prevalent congener PCB-153 was 113 ng/g lipid [interquartile range (IQR): 37-248], and 388 ng/g lipid (IQR: 115-847) for DDE. Higher 6-month infant concentrations of PCB-153 and DDE were strongly associated with lower 6-month BCG-specific antibody levels. For instance, BCG-specific IgG levels were 37% lower for infants with PCB-153 concentrations at the 75th percentile compared to the 25th percentile (95% CI: -42, -32; p < 0.001). Results were similar in magnitude and precision for DDE. There was also evidence of PCB-DDE additivity, where exposure to both compounds reduced anti-BCG levels more than exposure to either compound alone.

CONCLUSIONS

The associations observed in this study indicate that environmental exposures may be overlooked contributors to poorer responses to BCG vaccine. The overall association between these exposures and tuberculosis incidence is unknown.

CITATION

Jusko TA, De Roos AJ, Lee SY, Thevenet-Morrison K, Schwartz SM, Verner MA, Palkovicova Murinova L, Drobná B, Kočan A, Fabišiková A, Čonka K, Trnovec T, Hertz-Picciotto I, Lawrence BP. 2016. A birth cohort study of maternal and infant serum PCB-153 and DDE concentrations and responses to infant tuberculosis vaccination. Environ Health Perspect 124:813-821; http://dx.doi.org/10.1289/ehp.1510101.

Simple reaction time in 8-9-year old children environmentally exposed to PCBs

Simple reaction time (SRT) has been studied in children exposed to polychlorinated biphenyls (PCBs), with variable results. In the current work we examined SRT in 146 boys and 161 girls, aged 8.53 ± 0.65 years (mean ± SD), exposed to PCBs in the environment of eastern Slovakia. We divided the children into tertiles with regard to increasing PCB serum concentration. The mean ± SEM serum concentration of the sum of 15 PCB congeners was 191.15 ± 5.39, 419.23 ± 8.47, and 1315.12 ± 92.57 ng/g lipids in children of the first, second, and third tertiles, respectively. We created probability distribution plots for each child from their multiple trials of the SRT testing. We fitted response time distributions from all valid trials with the ex-Gaussian function, a convolution of a normal and an additional exponential function, providing estimates of three independent parameters μ, σ, and τ. μ is the mean of the normal component, σ is the standard deviation of the normal component, and τ is the mean of the exponential component. Group response time distributions were calculated using the Vincent averaging technique. A Q-Q plot comparing probability distribution of the first vs. third tertile indicated that deviation of the quantiles of the latter tertile from those of the former begins at the 40th percentile and does not show a positive acceleration. This was confirmed in comparison of the ex-Gaussian parameters of these two tertiles adjusted for sex, age, Raven IQ of the child, mother's and father's education, behavior at home and school, and BMI: the results showed that the parameters μ and τ significantly (p ≤ 0.05) increased with PCB exposure. Similar increases of the ex-Gaussian parameter τ in children suffering from ADHD have been previously reported and interpreted as intermittent attentional lapses, but were not seen in our cohort. Our study has confirmed that environmental exposure of children to PCBs is associated with prolongation of simple reaction time reflecting impairment of cognitive functions.

The spatial distribution of human exposure to PCBs around a former production site in Slovakia

We evaluated concentrations of 15 PCB congeners in blood serum of 2047 adults, 431 8-9-year old children and 1134 mother-child pairs born in 2001-2003. These subjects were long-standing residents living up to 70 km (to the north) and up to 50 km (to the south) of the former Chemko Strážske PCB production facility in the Michalovce district of Slovakia. We plotted serum concentration against distance from the plant both with and without consideration of the direction of their homes from the site. The decrease in exposure with distance could be described by an exponential function which was dependent on direction and climatic parameters. By kriging we created maps depicting predicted isoconcentration contours for sex- and age-adjusted serum concentration of ∑PCBs for the same group of children, adults and mothers. The principle of our risk analysis was to relate serum concentration data, reflecting PCB body burden, using the critical concentrations established by the French Agency for Food, Environmental and Occupational Health & Safety (ANSES 2010) as thresholds below which the probability of effects on health is regarded as negligible. We conclude that 10 years ago, around 200,000 residents were at risk in this densely populated area. Exposure has since decreased but the mechanism for this has not yet been studied.

Environmental exposure to organochlorine pesticides and deficits in cochlear status in children

The aim of this study was to examine the hypothesis that organochlorine pesticides (OCPs), hexachlorobenzene (HCB), β-hexachlorocyclohexane (β-HCH), and 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (p,p'-DDT) and its metabolite 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (p,p'- DDE) are ototoxic to humans. A multivariate general linear model was designed, in which the statistical relation between blood serum concentrations of HCB, β-HCH, p,p'-DDT, or p,p'-DDE at different ages (at birth, 6, 16, and 45 months) and the distortion product otoacoustic emissions (DPOAEs) was treated as multivariate outcome variables. Polychlorinated biphenyl (PCB) congeners and OCPs were strongly correlated in serum of children from our cohort. To ascertain that the association between DPOAEs at a given frequency and concentration of a pesticide is not influenced by PCBs or other OCP also present in serum, we calculated benchmark concentrations (BMCs) relating DPOAEs to a serum pesticide alone and in presence of confounding PCB-153 or other OCPs. We found that BMCs relating DPOAEs to serum pesticides are not affected by confounders. DPOAE amplitudes were associated with serum OCPs at all investigated time intervals, however, in a positive way with prenatal exposure and in a negative way with all postnatal exposures. We observed tonotopicity in the association of pesticides with amplitude of DPOAEs as its strength was frequency dependent. We conclude that exposure to OCPs in infancy at environmental concentrations may be associated with hearing deficits.

Ratio of cord to maternal serum PCB concentrations in relation to their congener-specific physicochemical properties

The aim was to characterize placental transfer of some congeners of polychlorinated biphenyls (PCBs) and to relate human in utero exposure to these pollutants to their physicochemical properties. We included into the study 1134 births during the period 2002-2003 from two highly PCB contaminated districts in eastern Slovakia. Concentrations of 15 PCB congeners (IUPAC No. 28, 52, 101, 123(+149), 118, 114, 153, 105, 138(+163), 167, 156(+171), 157, 180, 170, and 189) in umbilical cord (C) and maternal serum (M) were determined. The C/M ratios were significantly related, either positively or inversely depending on parameter, to the logarithm of partition coefficient octanol-water (KOW), to fusion enthalpy at the melting point, molecular weight, water solubility, total surface area of the molecule, solvent accessible surface area, melting point, molar volume, and molecular electronegativity distance vector. We found an inverse association between logKOW and lipid adjusted logC/M (const=1.078, b1=-0.179, p<0.001, R(2)=0.039). Parameters evaluated were interrelated except fusion enthalpy at the melting point and electron affinity vs. solubility. We discuss the possible role of cholesterol as a transplacental transporter of PCBs.

Duration of breastfeeding and serum PCB 153 concentrations in children

Polychlorinated biphenyls (PCBs) are toxic, persistent, and bioaccumulative chemicals which, because of their lipophilic properties, are abundant in human breast milk. Breastfed infants are therefore at risk of being exposed to considerable amounts of PCBs. The commonly used exposure estimations, based solely on breast milk PCB levels and duration of breastfeeding, may lead to exposure misclassification. To improve assessments of exposure to PCBs, we determined PCB 153 serum concentration, as a model substance for PCBs, at the critical time of weaning for each child in 305 breastfed infants from 5 single time point concentration measurements spread over 7 years and data on duration of breastfeeding, using an earlier developed model of the system type. We approximated the dependence of PCB 153 serum concentration, Ctbf, adjusted to cord serum concentration, C0, on nursing period, by a polynomial function Ctbf/C0=0.596+0.278t-0.0047t(2) which reliably predicts exposure to PCB 153 of breastfed infants, important for assessment of dose-outcome relationships. Adjustment of current serum concentrations to cord serum concentration improved validity of exposure assessment.

Polychlorinated biphenyls and selected organochlorine pesticides in serum of Slovak population from industrial and non-industrial areas

The concentrations of indicator polychlorinated biphenyls (PCBs No. 28, 52, 101, 138, 153 and 180) and organochlorine pesticides (HCB, p,p'-DDE and p,p'-DDT) in 121 blood serum specimens collected from non-occupationally exposed adults living in contaminated and comparison areas were determined using high-resolution gas chromatography/electron capture detection (HRGC/ECD). The sum of the serum concentrations of the three most abundant PCB congeners (No. 138, 153 and 180) found in participants (N = 81) living in industrial areas near incinerators, metallurgical and chemical plants (Krompachy, Kosice, Nemecka and Sala) was significantly higher (p < 0.001) than in participants living in villages and towns without known sources causing persistent organic pollutant (POP) contamination (N = 40). Similarly, significant differences were observed for p,p'-DDE (p < 0.0001) and p,p'-DDT (p < 0.002). However, a Mann-Whitney U test between groups showed that the difference for HCB was not statistically significant (p = 0.089). Age was positively correlated with the sum of PCBs (No. 138, 153 and 180), HCB and the sum of p,p'-DDE and p,p'-DDT (p < 0.01 for all).

Prenatal and postnatal serum PCB concentrations and cochlear function in children at 45 months of age

BACKGROUND

Some experimental and human data suggest that exposure to polychlorinated biphenyls (PCBs) may induce ototoxicity, though results of previous epidemiologic studies are mixed and generally focus on either prenatal or postnatal PCB concentrations exclusively.

OBJECTIVES

Our aim was to evaluate the association between pre- and postnatal PCB concentrations in relation to cochlear status, assessed by distortion product otoacoustic emissions (DPOAEs), and to further clarify the critical periods in development where cochlear status may be most susceptible to PCBs.

METHODS

A total of 351 children from a birth cohort in eastern Slovakia underwent otoacoustic testing at 45 months of age. Maternal pregnancy, cord, and child 6-, 16-, and 45-month blood samples were collected and analyzed for PCB concentrations. At 45 months of age, DPOAEs were assessed at 11 frequencies in both ears. Multivariate, generalized linear models were used to estimate the associations between PCB concentrations at different ages and DPOAEs, adjusting for potential confounders.

RESULTS

Maternal and cord PCB-153 concentrations were not associated with DPOAEs at 45 months. Higher postnatal PCB concentrations at 6-, 16-, and 45-months of age were associated with lower (poorer) DPOAE amplitudes. When all postnatal PCB exposures were considered as an area-under-the-curve metric, an increase in PCB-153 concentration from the 25th to the 75th percentile was associated with a 1.6-dB SPL (sound pressure level) decrease in DPOAE amplitude (95% CI: -2.6, -0.5; p = 0.003).

CONCLUSIONS

In this study, postnatal rather than maternal or cord PCB concentrations were associated with poorer performance on otoacoustic tests at age 45 months.

Comparison of solvent extraction and solid-phase extraction for the determination of polychlorinated biphenyls in transformer oil

Solid-phase extraction (SPE) of nine polychlorinated biphenyls (PCBs) from transformer oil samples was evaluated using octadecyl (CI8)-bonded porous silica. The efficiency of SPE of these PCBs was compared with those obtained by solvent extraction with DMSO and hexane. Average recoveries exceeding 95% for these PCBs were obtained via the SPE method using small cartridges containing 100mg of 40 pm CI8-bonded porous silica. The average recovery by solvent extraction with DMSO and hexane exceeded 83%. It was concluded that the recoveries and precision for the solvent extraction of PCBs were poorer than those for the SPE.

Anthropometric, socioeconomic, and maternal health determinants of placental transfer of organochlorine compounds

The aim of this study was to relate placental transfer, quantified by the cord to maternal serum concentration ratio (C/M), of five organochlorine pesticides (OCP) hexachlorobenzene (HCB), β-hexachlorocyclohexane (β-HCH), γ-hexachlorocyclohexane (γ-HCH) , p,p'-DDT, p,p'-DDE and 15 polychlorinated biphenyl (PCB) congeners (28, 52, 101, 105, 114, 118, 123(+149), 138(+163), 153, 156(+171), 157, 167, 170, 180, and 189) to anthropometric, socioeconomic, and maternal health characteristics. We included into the study 1,134 births during the period 2002-2004 from two districts in eastern Slovakia with high organochlorine concentrations relative to other areas of the world. Only concentrations >LOD were taken into account. Variables as age, weight and height of mothers, parity, ethnicity, alcohol consumption, illness during pregnancy, smoking during pregnancy, hypertension, respiratory diseases, rheumatoid arthritis and diabetes mellitus, and birth weight were related to C/M. Results of regression analyses showed that C/M was predicted by several factors studied. Positive associations were observed for gestational alcohol consumption, fewer illnesses during pregnancy, maternal age, and maternal weight. Caucasians had a greater C/M compared to Romani for wet weight data of congeners 170 and 180 and in contrast C/M for HCB was greater in Romani. Our results show that drinking mothers compared to abstaining expose their fetuses not only to alcohol but to an increased level of several PCB congeners. A straightforward explanation of associations between C/M shifts and factors studied is very difficult, however, with regard to the high lipophilicity of OCPs and PCBs, changes in their kinetics probably reflect lipid kinetics.

Estrogen receptors are involved in polychlorinated biphenyl-induced apoptosis on mouse spermatocyte GC-2 cell line

Polychlorinated biphenyls (PCBs) are widespread persistent environmental contaminants which have been shown to have reproductive toxicity and to disturb spermatogenesis. But the precise mechanism is not clear. A mouse pachytene spermatocyte-derived cell line, GC-2 cells were used in the present study to investigate the toxic effect of PCBs (Aroclor 1254) and explore the underlying molecular mechanism. Results showed that Aroclor 1254 inhibited cell proliferation, caused the arrest of cells in G0/G1 phase and induced apoptosis which might be partly explained by the decreased expression of Bcl-2 and cell cycle regulator cyclin D1 together with the activation of caspase-3. Besides, the treatment of Aroclor 1254 decreased the protein expression of estrogen receptor (ER)-α while increasing that of ERβ. Then the administration of selective ERα agonist PPT partly reversed Aroclor 1254-induced alteration in Bcl-2, caspase-3 and cyclin D1 protein expression while selective ERβ agonist DPN accelerated it. These results suggest that Aroclor 1254, working through ERα and ERβ, interferes with the expression of proteins involved in the balance between cellular apoptosis and proliferation.

Determination of selected perfluorinated alkyl acids and persistent organic pollutants from a small volume human serum sample relevant for epidemiological studies

A simple and fast method is presented for the determination of selected persistent organic pollutants (POPs) and perfluorinated alkyl acids (PFAAs), a subgroup of per- and polyfluorinated alkyl substances (PFAS) from a single 200μl aliquot of serum. Sample pretreatment starts with dispersive solid phase extraction of POPs to dichloromethane-hexane, which is immediately poured to cleanup column. POPs are eluted from column and concentrated for GC-MS/MS analysis. PFAAs are trapped to dispersant and are then extracted with ammonium acetate in methanol, concentrated and analysed with LC-MS/MS. For POPs, the limit of detection (LOD) ranged from 1.6 to 17pg/ml. Oxychlordane and dichlorodiphenyltrichloroethane had LODs in the upper end of this range as they were more labile and prone for interferences in the GC-MS/MS. For PFAAs, the LOD range from 0.027 to 0.068ng/ml. For POPs, the accuracy from Standard Reference Materials SRM 1589a and Arctic Monitoring and Assessment Programme (AMAP) intercalibration samples range from 74 to 127% and the repeatability (relative standard deviation, RSD%) from 2.0 to 15%. For PFAAs, the accuracy from AMAP samples ranged from 90 to 110% and from LOQ level spiked serum samples from 72 to 133%. Repeatability from AMAP and LOQ samples ranged from 1.6 to 7.3% and 5.5 to 15%, respectively. The presented method is useful in epidemiological studies where only limited amount of serum is available.

Extraction of ultra traces of polychlorinated biphenyls in aqueous samples using suspended liquid-phase microextraction and gas chromatography-electron capture detection

This study reports the feasibility of applying directly suspended liquid-phase microextraction (DSLPME)-gas chromatography detection for the pre-concentration and determination of low levels of eight polychlorinated biphenyls (PCBs) in aqueous samples. The technique requires minimal sample preparation, analysis time and solvent consumption and represents significant advantages over conventional analytical methods. The experimental parameters such as salt content, sample temperature, stirring rate, extraction time, micro-drop volume and breakthrough volume were investigated and found to have significant influences on DSLPME. Under the optimal experimental conditions, the enrichment factor ranged from 578 to 729, and the recovery was above 93 %. Calibration curves possessed good linearity (R(2) > 0.99) over a wide concentration range of 0.1-10.0 μg L(-1) with limits of detection ranging from 0.01 to 0.07 μg L(-1). The relative standard deviations for 1.0 μg L(-1) of PCBs in water by using internal standard were in the range 2-14 % (n = 3). The proposed simple, accurate and sensitive analytical method was applied successfully to the determination of trace amounts of PCBs in water samples.

Enrichment of polychlorinated biphenyls from aqueous solutions using Fe₃O₄ grafted multiwalled carbon nanotubes with poly dimethyl diallyl ammonium chloride

In this paper, Fe(3)O(4) nanoparticles (Fe(3)O(4) NPs) grafted carboxyl groups of multiwalled carbon nanotubes with cationic polyelectrolyte poly (dimethyldiallylammonium chloride) (PDDA) (MWCNTs-COO(-)/PDDA@Fe(3)O(4)), are successfully synthesized and used for the extraction of six kinds of major toxic polychorinated biphenyls (PCBs) from a large volume of water solution. The hydrophilicity of the PDDA cage can enhance the dispersibility of sorbents in water samples, and the superparamagnetism of the Fe(3)O(4) NPs facilitate magnetic separation which directly led to the simplification of the extraction procedure. With the magnetic solid-phase extraction (MSPE) technique based on the MWCNTs-COO(-)/PDDA@Fe(3)O(4) sorbents, it requires only 30 min to extract trace levels of PCBs from 500 mL water samples. When the eluate condensed to 1.0 mL, concentration factors for PCBs became over 500. The spiked recoveries of several real water samples for PCBs were in the range of 73.3-98.9% with relative standard deviations varying from 3.8% to 9.4%, reflecting good accuracy of the method. Therefore, preconcentration of trace level of PCBs by using this MWCNTs-COO(-)/PDDA@Fe(3)O(4) sorbent, which are stable for multiple reuses, from water solution can be performed.

Pre- and postnatal polychlorinated biphenyl concentrations and longitudinal measures of thymus volume in infants

BACKGROUND

Previously, we reported an association between higher maternal polychlorinated biphenyl (PCB) concentrations and smaller thymus volume in newborns in a birth cohort residing in eastern Slovakia.

OBJECTIVE

In the present report we address whether thymus volume at later ages is influenced by prenatal and early postnatal PCB exposure.

METHODS

At the time of delivery, 1,134 mother-infant pairs were enrolled. Maternal and 6- and 16-month infant blood samples were collected and analyzed for 15 PCB congeners. Thymus volume was measured in infants shortly after birth and at ages 6 and 16 months using ultrasonography.

RESULTS

Higher maternal PCB concentration was associated with reduced thymus volume at birth [a 0.21 SD reduction in thymus volume for an increase in total maternal PCB concentration from the 10th to the 90th percentile; 95% confidence interval (CI): -0.37, -0.05], whereas maternal PCB concentration was not predictive of 6- and 16-month thymus volume. Six-month infant PCB concentration was associated with a 0.40 SD decrease in 6-month thymus volume (95% CI: -0.76, -0.04). There was also some suggestion that thymus volume at 16 months was positively associated with concurrent infant PCB concentration.

CONCLUSIONS

The potential adverse effects of in utero PCB exposure on thymic development may extend beyond the neonatal period. Results from this highly exposed cohort provide suggestive evidence that postnatal PCB concentrations may be influential, but a smaller set of 6-month PCB measurements limited statistical power at that time point. Implications regarding impaired immunologic maturation or long-term clinical implications remain to be determined.

The kinetics of cell surface receptor expression in children perinatally exposed to polychlorinated biphenyls

Exposure to polychlorinated biphenyls (PCBs) during pre-natal and early life can alter normal immune system development. Blood specimens from newborns, 6-, and 16-month-old infants were collected in the Michalovce and Svidnik/Stropkov districts, areas with, respectively, high and low environmental PCB contamination, and lymphocyte receptor expression was evaluated by multi-color flow cytometry. The results indicate that the percentage of lymphoid dendritic cells (DC) and naïve/resting T-lymphocytes were significantly increased at 6-months in Michalovce as compared to the same cell types in cord blood samples (p < 0.001), whereas natural regulatory T-lymphocytes and suppressor inducer T-lymphocytes were reduced (p < 0.001). Overall, a positive linear correlation of terminally differentiated effector memory (TEM) T-lymphocyte population with age, but a negative linear correlation for myeloid DC from birth to 6-months in both regions were found. Michalovce samples indicated significantly higher expression of memory T-lymphocytes (birth, 6(th), and 16(th) month), TEM T-lymphocytes (birth and 6(th) month), and lymphoid DC (6(th) month) compared to the Svidnik/Stropkov regions. After adjustment for relevant covariates, such as maternal age, parity, season of birth, breastfeeding, birth weight, and gender, the myeloid DC, suppressor inducer T-lymphocytes, truly naïve helper/inducer T-lymphocytes, and TEM T-lymphocytes remained significantly different between districts in cord blood samples. The multivariate analysis models for 6- and 16-month samples showed district differences in all cellular determinants, except for lymphoid DC and macrophage-like cells. This study provides the first evidence that pre-natal and early post-natal exposure to PCBs affects the dynamics of cell surface receptor expression on lymphoid DC and DC-like cells, suggesting impaired immunologic development following pre-natal and early post-natal PCB exposure.

A rapid method for screening of the Stockholm Convention POPs in small amounts of human plasma using SPE and HRGC/HRMS

A rapid analytical screening method allowing simultaneous analysis of 23 persistent organic pollutants (POPs) in human plasma was developed. Sample preparation based on solid-phase extraction (SPE) with additional clean-up using small multilayer silica gel columns. SPE was performed using a custom made polystyrene-divinylbenzene sorbent for the extraction of chlorinated and brominated POPs. Special efforts to reduce sample volume and improve speed and efficiency of the analytical procedure were made. Determination of 16 polychlorinated biphenyls (PCBs), 5 organochlorine (OC) pesticides, octachlorinated dibenzo-p-dioxin (OCDD) and polybrominated diphenyl ether (BDE #47) in 0.5 mL human plasma was performed by using high resolution gas chromatography coupled to high resolution mass spectrometry (HRGC/HRMS). Recovery of POPs ranged between 46% and 110%, and reproducibility was below 25% relative standard deviation (RSD) for all target compounds, except for trans-nonachlor and OCDD, which were present only at low levels. Limits of detection (LOD) were for the PCBs between 0.8 and 117.7 pg mL(-1) plasma and for the OC pesticides between 5.9 and 89.1 pg mL(-1) plasma. The LOD for OCDD and BDE #47 were 1.4 pg mL(-1) plasma, and 9.2 pg mL(-1) plasma, respectively. The presented method was successfully applied to 1016 human plasma samples from an epidemiological study on cardiovascular disease.

Assessment of exposure to PCB 153 from breast feeding and normal food intake in individual children using a system approach model

Investigators have typically relied on a single or few discrete time points as measures of polychlorinated biphenyl (PCB) body burden, however health effects are more likely to be the result of integrative exposure in time, optionally expressed as an area under the time curve (AUC) of PCB serum concentration. Using data from a subgroup of 93 infants from a birth cohort in eastern Slovakia-a region highly polluted by PCBs-we fit a system type model, customized to our longitudinal measures of serum PCB concentrations in cord, 6, 16, and 45 month blood specimens. The most abundant congener, PCB 153, was chosen for modeling purposes. In addition to currently used methods of exposure assessment, our approach estimates a concentration time profile for each subject, taking into account mean residence time of PCB 153 molecules in the body, duration of breast feeding, hypothetical PCB 153 concentration in steady-state without breast feeding and alternately without normal food intake. Hypothetical PCB 153 concentration in steady-state without normal food intake correlates with AUC (r=0.84, p<0.001) as well as with duration of breast feeding (r=0.64, p<0.001). It makes possible to determine each subject's exposure profile expressed as AUC of PCBs serum concentration with a minimum model parameters. PCB body burden in most infants was strongly associated with duration of breast feeding in most, but not all children, was apparent from model output.

Relationship between serum concentrations of polychlorinated biphenyls and organochlorine pesticides and dietary habits of pregnant women in Shanghai

The use of most polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) has been restricted in China; however, their use remains a concern because of their adverse effects on human health, especially on fetuses and infants. To date, there is no data regarding the exposure levels of pregnant women to PCBs and OCPs in Shanghai. In order to evaluate PCB and OCP exposure levels and the contribution of dietary habits to these levels, we determined the concentrations of 8 PCBs and 14 OCPs in the umbilical cord blood serum of healthy pregnant women in Shanghai. Dietary habits of the pregnant women were obtained from a self-administered questionnaire. Results showed that p, p'-DDE, HCB and β-HCH were the major pollutants present in the serum samples; PCBs were detected in a few samples at low concentrations. Age, weight and body mass index before delivery were positively associated with serum levels of p, p'-DDE and β-HCH. Women and their husbands who had higher education levels, higher income levels, tended to have higher levels of p, p'-DDE and β-HCH. Spearman correlation analysis results suggested that consumption of foods such as milk, eggs, meat, fish, and shrimp may contribute to higher serum levels of p, p'-DDE and β-HCH. Furthermore, multiple linear regression analyses indicated that the age and educational levels of the pregnant women and their intake of fried/flamed food and shellfish were positively associated with β-HCH levels, and that the age and educational levels of the pregnant women and their intake of parity, beef, pork, mutton, and shrimp were positively associated with p, p'-DDE levels. This is the first study to investigate the exposure levels of pregnant women to PCBs and OCPs in Shanghai, and it should provide useful information for future related research.

Maternal and early postnatal polychlorinated biphenyl exposure in relation to total serum immunoglobulin concentrations in 6-month-old infants

Animal data indicate that developmental tetrachlorodibenzo-p-dioxin exposure alters immune function; however, the potential immunotoxicity of dioxin-like and non-dioxin-like polychlorinated biphenyls (PCBs) in the developing infant is an understudied area. The aim of the current study is to examine the association between maternal and early postnatal PCB concentrations in relation to total infant serum immunoglobulin concentrations determined at 6-months-of-age. We selected 384 mother-infant pairs participating in a birth cohort study in Eastern Slovakia. PCB concentrations of several congeners were determined in maternal and cord serum samples and in infant serum samples collected at 6-months-of-age using gas chromatography with electron capture detection. Total immunoglobulin (Ig) G, A, and M concentrations were determined by nephelometry, and IgE concentrations were determined by enzyme-linked immunoassay. Linear regression models with adjustment for potential confounding factors were used to estimate the associations between maternal, cord, and 6-month infant PCB concentrations and total serum immunoglobulins. The median maternal serum concentration of PCB-153 was 140?ng/g lipid, ?10-fold higher than concentrations in childbearing-age women in the United States during the same period. Maternal, cord, or 6-month infant PCB concentrations were not associated with total serum immunoglobulin levels at 6 months, regardless of the timing of PCB exposure, PCB congener, or specific immunoglobulin. In this population, which has high PCB concentrations relative to most populations in the world today, we did not observe any association between maternal and early postnatal PCB concentrations and total immunoglobulin measures of IgG, IgA, IgM, or IgE.

Half-lives of serum PCB congener concentrations in environmentally exposed early adolescents

The aim was to determine half-life of six most abundant PCB congeners in the body of early adolescents. In 304 environmentally exposed children, PCB serum concentration was determined at the age of 8 and 12years. Half-life was determined for each child assuming exponential decrease or for the whole cohort using multiple regression. Results obtained by both approaches were in agreement. PCB reuptakes corrupting half-life estimates for each child and each congener were evaluated. If one of the serum PCB concentration values fell below the level of detection (LOD) the pair was excluded and if PCB half-life value exceeded the arbitrary value of 30years. The following median half-lives in years 4.46, 10.59, 9.7, 4.7, 9.1 and 9.8 were obtained for PCB congeners 118, 138(+163), 153, 156(+171), 170 and 180, respectively. The elimination half-life values were not systematically related to PCB serum concentration at any examination age. Between half-life values, percentage of children with significant reuptakes and PCB congener abundance in serum were found significant associations.

Analysis of agricultural residues on tea using d-SPE sample preparation with GC-NCI-MS and UHPLC-MS/MS

This study presents new sample preparation and analytical procedures for the quantification of pesticides on processed tea leaves. The new method includes tea extraction and dispersive solid phase extraction (d-SPE) to prepare gas chromatography (GC) and ultrahigh-performance liquid chromatography (UHPLC)-ready samples, providing a fast and cost-effective solution for time-sensitive industrial analysis to fulfill regulatory requirements. Both GC-negative chemical ionization mass spectrometry (GC-NCI-MS) and UHPLC-tandem mass spectrometry (UHPLC-MS/MS) were employed to produce highly sensitive and reproducible data. Excellent limits of detection (typically below 1 μg/kg for GC and 10 μg/kg for UHPLC), wide linearity ranges, and good recoveries (mostly >70%) were achieved on the selected pesticides. Twenty-seven tea samples purchased from local grocery stores were analyzed using the newly developed methods. Among the pesticides analyzed, endosulfan sulfate and kelthane were the most frequently detected by GC-NCI-MS and imidacloprid and acetamiprid by UHPLC-MS/MS in these teas. The samples were found to be relatively clean, with <1 mg/kg of total pesticide residues. The organic-labeled teas were significantly cleaner than nonorganic ones. The cost per gram of tea did not correlate with pesticide residue levels detected.