Distribution and Predictors of Pesticides in the Umbilical Cord Blood of Chinese Newborns

Effects of chronic insecticide exposure on neuronal network development in vitro in rat cortical cultures

Developmental exposure to carbamates, organophosphates, and pyrethroids has been associated with impaired neurodevelopmental outcomes. Sex-specific differences following chronic insecticide exposure are rather common in vivo. Therefore, we assessed the chronic effects of in vitro exposure to different carbamates (carbaryl, methomyl and aldicarb), organophosphates [chlorpyrifos (CPF), chlorpyrifos-oxon (CPO), and 3,5,6,trichloropyridinol (TCP)], and pyrethroids [permethrin, alpha-cypermethrin and 3-phenoxy benzoic acid (3-PBA)] on neuronal network development in sex-separated rat primary cortical cultures using micro-electrode array (MEA) recordings. Our results indicate that exposure for 1 week to carbaryl inhibited neurodevelopment in male cultures, while a hyperexcitation was observed in female cultures. Methomyl and aldicarb evoked a hyperexcitation after 2 weeks of exposure, which was more pronounced in female cultures. In contrast to acute MEA results, exposure to ≥ 10 µM CPF caused hyperexcitation in both sexes after 10 days. Interestingly, exposure to 10 µM CPO induced a clear hyperexcitation after 10 days of exposure in male but not female cultures. Exposure to 100 µM CPO strongly inhibited neuronal development. Exposure to the type I pyrethroid permethrin resulted in a hyperexcitation at 10 µM and a decrease in neuronal development at 100 µM. In comparison, exposure to ≥ 10 µM of the type II pyrethroid alpha-cypermethrin decreased neuronal development. In female but not in male cultures, exposure to 1 and 10 µM permethrin changed (network) burst patterns, with female cultures having shorter (network) bursts with fewer spikes per (network) burst. Together, these results show that MEA recordings are suitable for measuring sex-specific developmental neurotoxicity in vitro. Additionally, pyrethroid exposure induced effects on neuronal network development at human-relevant concentrations. Finally, chronic exposure has different effects on neuronal functioning compared to acute exposure, highlighting the value of both exposure paradigms.

Prenatal exposure to pyrethroids and chlorpyrifos and IQ in 7-year-old children from the Odense Child Cohort

BACKGROUND

Organophosphates and pyrethroids are two major groups of insecticides used for crop protection worldwide. They are neurotoxicants and exposure during vulnerable windows of brain development may have long-term impact on human neurodevelopment. Only few longitudinal studies have investigated associations between prenatal exposure to these substances and intelligence quotient (IQ) at school age in populations with low, mainly dietary, exposure.

OBJECTIVE

To investigate associations between maternal urinary concentrations of insecticide metabolites at gestational week 28 and IQ in offspring at 7-years of age.

MATERIALS AND METHODS

Data was derived from the Odense Child Cohort (OCC). Metabolites of chlorpyrifos (TCPy) and pyrethroids (3-PBA, cis- and trans-DCCA, 4-F-3PBA, cis-DBCA) were measured in maternal urine collected at gestational week (GW) 28. An abbreviated version of the Danish Wechsler Intelligence Scale for Children fifth edition (WISC-V) consisting of four subtests to estimate full scale IQ (FSIQ) was administered by trained psychologists. Data were analyzed by use of multiple linear regression and adjusted for confounders.

RESULTS

812 mother/child-pairs were included. Median concentrations were 0.21 μg/L for 3-PBA, 1.67 μg/L for TCPy and the mean IQ for children were 99.4. Null association between maternal 3-PBA and child IQ at 7 years was seen, but with trends suggesting an inverse association. There was a significant association for maternal TCPy and child IQ at mid-level exposure. Trans-DCCA above the level of detection (LOD) was also associated with slightly lower child IQ, but the association was also not statistically significant.

CONCLUSIONS

We found no significant associations between maternal 3-PBA metabolites and child IQ at 7 years, but with trends suggesting an inverse association. A non-significant trend between maternal TCPy exposure and child IQ in 7-year-children was seen even in this low exposed population. Given the widespread exposure and increasing use of insecticides, this should be elaborated in future studies.

[New advances in exposomics-analysis methods and research paradigms based on chromatography-mass spectrometry]

The occurrence and development of human diseases are influenced by both genetic and environmental factors. Research models that describe disease occurrence only from the perspective of genetics present certain limitations. In recent years, effects of environment factors on the occurrence and development of diseases have attracted extensive attentions. Exposomics focuses on the measurement of all exposure factors in an individual's life and how these factors are related to disease development. Exposomics provides new ideas to promote studies on the relationship between human health and environmental factors. Environmental exposures are characterized with different physical and chemical properties, as well as very low concentrations in vivo, which contribute great challenges in the comprehensive measurement of chemical residues in the human body. Chromatography-mass spectrometry-based technologies combine the high-efficiency separation ability of chromatography with the high resolution and sensitive detection characteristics of mass spectrometry; the combination of these techniques can achieve the high-coverage, high-throughput, and sensitive detection of environmental exposures, thus providing a powerful tool for measuring chemical exposures. Exposomics-analysis methods based on chromatography-mass spectrometry mainly include targeted quantitative analysis, suspect screening, and non-targeted screening. To explore the relationship between environmental exposure and the occurrence and development of diseases, researchers have developed research paradigms, including exposome wide association study, mixed-exposure study, exposomics and multi-omics (genome, transcriptome, proteome, metabolome)-association study, and so on. The emergence of these methods has brought about unprecedented developments in exposomics studies. In this manuscript, analytical methods based on chromatography-mass spectrometry, exposomics research paradigms, and their relevant prospects are reviewed.

Exposure to chlorpyrifos and pyrethroid insecticides and symptoms of Attention Deficit Hyperactivity Disorder (ADHD) in preschool children from the Odense Child Cohort

BACKGROUND

Attention Deficit Hyperactivity Disorder (ADHD) is a common childhood psychiatric disorder with severe and lifelong impact on mental health and socioeconomic achievements. Environmental factors may play a role in the increasing incidens rates. Previous studies on associations between prenatal and childhood exposure to organophosphate and pyrethroid insecticides and ADHD symptoms have yielded mixed findings.

OBJECTIVES

To investigate associations between prenatal and childhood exposure to chlorpyrifos and pyrethroids and ADHD symptoms in 5-year-old children from the Odense Child Cohort.

METHODS

Spot urine samples from pregnant women in gestational week 28 (n = 614) and offspring at 5 years of age (n = 814) were collected and analyzed for the specific metabolite of chlorpyrifos, TCPY (3,5,6-trichloro-2-pyridinol), as well as the generic pyrethroid metabolite, 3-PBA (3-phenoxybenzoic acid). Offspring ADHD symptoms were assessed at age 5 years using the parent reported "ADHD scale" from the "Child Behavior Checklist 1½-5" (n = 1114). Associations between insecticide exposure variables and an ADHD score ≥90th percentile were analyzed using logistic regression for all children and stratified by sex.

RESULTS

Most pregnant women had detectable concentrations of 3-PBA (93%) and TCPY (91%) with median concentrations of 0.20 μg/L and 1.62 μg/L, respectively. In children, 3-PBA and TCPY concentrations were detectable in 88% and 82% of the samples, and the median concentrations were 0.17 and 1.16 μg/L. No statistically significant associations were observed between insecticide metabolites and an ADHD score ≥90th percentile at age 5.

CONCLUSION

In this relatively large Danish birth cohort study with mainly low dietary insecticide exposure, we found no statistically significant associations between prenatal or childhood exposure to chlorpyrifos or pyrethroids, and excess ADHD-symptom load, in 5-year-old children. Prospective studies with multiple urine samples across vulnerable windows of neurodevelopment is warranted to improve assessment of safe exposure levels, which is particularly relevant for pyrethroids, since their use is increasing.

Autophagy perturbation upon acute pyrethroid treatment impacts adipogenic commitment of mesenchymal stem cells

Environmental chemical exposure can cause dysregulation in adipogenesis that can result in metabolic syndrome, which includes insulin resistance, type 2 diabetes, cardiovascular disease, as well as excessive body weight. The role of autophagy in adipocyte differentiation is debatable since both positive and negative effects have been reported. Type-I and type-II synthetic pyrethroids α-cypermethrin (CPM) and permethrin (PER), respectively, are reported to increase adipogenesis in vitro and in vivo. However, it is not known how these pyrethroids affect mesenchymal stem cells (MSCs). Thus, this study focused on evaluating the effect of pyrethroids (CPM and PER) pre-treatment (24 h) on MSC commitment and the regulatory role of autophagy in adipogenic lineage commitment. The formation of adipocytes was observed through nile red staining, perilipin expression by immunoflourescence, and adipogenic markers PPARγ, C/EBPα, and FABP4 by western blotting. It was found that the adipogenic differentiation ability of MSCs was significantly increased upon CPM or PER pre-treatment at 100 μM concentration as evident by lipid accumulation and enhanced expression of adipogenic markers. To assess the involvement of autophagy, the expression of p62 and LC3II were evaluated following pre-treatment. Immunoblotting results revealed an increased expression of p62 and LC3II in CPM or PER pretreated MSCs suggesting CPM and PER mediated inhibition of autophagy at 24 h. Further, an increase was observed in adipogenesis upon CPM or PER pre-treatment in combination with chloroquine, while use of rapamycin during pre-treatment abrogated the effect of CPM and PER. Thus, this study concludes that CPM or PER pre-treatment increases the adipogenic differentiation of MSCs. Since chloroquine also demonstrated similar adipogenic response, it further highlights that 24 h pre-treatment with autophagy modulators to inhibit basal autophagy primes MSCs towards adipogenic lineage.

Exploring the effects and mechanisms of organophosphorus pesticide exposure and hearing loss

Many environmental factors, such as noise, chemicals, and heavy metals, are mostly produced by human activities and easily induce acquired hearing loss. Organophosphorus pesticides (OPs) constitute a large variety of chemicals and have high usage with potentiate damage to human health. Moreover, their metabolites also show a serious potential contamination of soil, water, and air, leading to a serious impact on people's health. Hearing loss affects 430 million people (5.5% of the global population), bringing a heavy burden to individual patients and their families and society. However, the potential risk of hearing damage by OPs has not been taken seriously. In this study, we summarized the effects of OPs on hearing loss from epidemiological population studies and animal experiments. Furthermore, the possible mechanisms of OP-induced hearing loss are elucidated from oxidative stress, DNA damage, and inflammatory response. Overall, this review provides an overview of OP exposure alone or with noise that leads to hearing loss in human and experimental animals.

Maternal and fetal tissue distribution of α-cypermethrin and permethrin in pregnant CD-1 mice

Pyrethroid insecticides are widely used throughout agriculture and household products. Recent studies suggest that prenatal exposure to these insecticides may adversely affect fetal development; however, little is known about the distribution of these chemicals in pregnant animals. The present study aimed to address this gap in knowledge by investigating the distribution of two commonly used pyrethroid insecticides, permethrin and α-cypermethrin, in maternal and fetal tissues of pregnant CD-1 mice. Dams were dosed from gestational days 6 to 16 via oral gavage with permethrin (1.5, 15, and 50 mg/kg), α-cypermethrin (0.3, 3, and 10 mg/kg), or corn oil vehicle. Pyrethroid levels were determined in gestational day 16 tissues collected 90 min after the final dose was administered. Across maternal tissues, levels of both pyrethroids were the highest in maternal ovaries, followed by liver and brain, respectively. In addition, levels of both pyrethroids in maternal tissues and placenta were significantly higher than those in the fetal body and amniotic fluid, suggesting that these compounds may exhibit low transfer across the mouse placenta. While additional toxicokinetic studies are needed to verify the time course of pyrethroids in the fetal compartment, these findings support investigation into indirect modes of action relevant to the effects of pyrethroids on mammalian fetal development.

A narrative review of converging evidence addressing developmental toxicity of pyrethroid insecticides

Pyrethroid insecticides are broadly used in agriculture and household products throughout the world. Exposure to this class of insecticides is widespread, and while generally believed to be safe for use, there is increasing concern regarding their effects on neurodevelopment. Due to the critical roles that molecular targets of pyrethroids play in the regulation of neurodevelopment, particular focus has been placed on evaluating the effects of in utero and childhood pyrethroid exposure on child cognition and behavior. As such, this narrative review synthesizes an assessment of converging study types; we review reports of neonatal pyrethroid levels together with current epidemiological literature that convergently address the risk for developmental toxicity linked to exposure to pyrethroid insecticides. We first address studies that assess the degree of direct fetal exposure to pyrethroids in utero through measurements in cord blood, meconium, and amniotic fluid. We then focus on the links between prenatal exposure to these insecticides and child neurodevelopment, fetal growth, and other adverse birth outcomes. Furthermore, we assess the effects of postnatal exposure on child neurodevelopment through a review of the data on pediatric exposures and child cognitive and behavioral outcomes. Study quality was evaluated individually, and the weight of evidence was assessed broadly to characterize these effects. Overall, while definitive conclusions cannot be reached from the currently available literature, the available data suggest that the potential links between pyrethroid exposure and child neurodevelopmental effects deserve further investigation.

Phosphate-triggered ratiometric fluoroimmunoassay based on nanobody-alkaline phosphatase fusion for sensitive detection of 1-naphthol for the exposure assessment of pesticide carbaryl

The excessive use of carbaryl has resulted in the risk of its exposure. In this study, we isolated six nanobodies (Nbs) from a camelid phage display library against the biomarker of carbaryl, 1-naphthol (1-NAP). Owing to its characteristics of easy genetic modifications, we produced a nanobody-alkaline phosphatase (Nb-CC4-ALP) fusion protein with good stability. A dual-emission system based ratiometric fluoroimmunoassay (RFIA) for quick and highly sensitive determination of 1-NAP was developed. Silicon nanoparticles (SiNPs) was used as an internal reference and for aggregation-induced emission enhancement (AIEE) of gold nanoclusters (AuNCs), while AuNCs could be quenched by MnO2 via oxidation. In the presence of ALP, ascorbic acid phosphate (AAP) can be transformed into ascorbic acid (AA), the later can etch MnO2 to recover the fluorescence of the AuNCs. Based on optimal conditions, the proposed assay showed 220-fold sensitivity improvement in comparison with conventional monoclonal antibody-based ELISA. The recovery test of urine samples and the validation by standard HPLC-FLD demonstrated the proposed assay was an ideal tool for screening 1-NAP and provided technical support for the monitoring of carbaryl exposure.

Metabolome-wide association study of serum exogenous chemical residues in a cohort with 5 major chronic diseases

BACKGROUND

Chronic diseases have become main killers affecting the health of human, and environmental pollution is a major health risk factor that cannot be ignored. It has been reported that exogenous chemical residues including pesticides, herbicides, fungicides, veterinary drugs and persistent organic pollutants are associated with chronic diseases. However, the evidence for their relationship is equivocal and the underlying mechanisms are unclear.

OBJECTIVES

We aim to investigate the linkages between serum exogenous chemical residues and 5 main chronic diseases including obesity, hyperuricemia, hypertension, diabetes and dyslipidemia, and further reveal the metabolic perturbations of chronic diseases related to exogenous chemical residue exposure, then gain potential mechanism insight at the metabolic level.

METHODS

LC-MS-based targeted and nontargeted methods were respectively performed to quantify exogenous chemical residues and acquire metabolic profiling of 496 serum samples from chronic disease patients. Non-parametric test, correlation and regression analyses were carried out to investigate the association between exogenous chemical residues and chronic diseases. Metabolome-wide association study combined with the meeting-in-the-middle strategy and mediation analysis was performed to reveal and explain exposure-related metabolic disturbances and their risk to chronic diseases.

RESULTS

In the association analysis of 106 serum exogenous chemical residues and 5 chronic diseases, positive associations of serum perfluoroalkyl substances (PFASs) with hyperuricemia were discovered while other associations were not significant. 240 exposure markers of PFASs and 84 disease markers of hyperuricemia were found, and 47 of them were overlapped and considered as putative effective markers. Serum uric acid, amino acids, cholesterol, carnitines, fatty acids, glycerides, glycerophospholipids, ceramides, and a part of sphingolipids were positively correlated with PFASs and associated with increased risk for hyperuricemia. Creatine, creatinine, glyceryl monooleate, phosphatidylcholine 36:6, phosphatidylethanolamine 40:6, cholesterol and sphingolipid 36:1;2O were significant markers which mediated the associations of the residues with hyperuricemia.

CONCLUSIONS

Our study demonstrated a significantly positive association between PFASs exposure and hyperuricemia. The most significant metabolic abnormality was lipid metabolism which not only was positively associated with PFASs, but also increased the risk of hyperuricemia.

Multi Species Analyses Reveal Testicular T3 Metabolism and Signalling as a Target of Environmental Pesticides

Thyroid hormones (THs) regulate many biological processes in vertebrates, including reproduction. Testicular somatic and germ cells are equipped with the arrays of enzymes (deiodinases), transporters, and receptors necessary to locally maintain the optimal level of THs and their signalling, needed for their functions and spermatogenesis. Pesticides, as chlorpyrifos (CPF) and ethylene thiourea (ETU), impair the function of thyroid and testis, affecting male fertility. However, their ability to disarrange testicular T3 (t-T3) metabolism and signalling is poorly considered. Here, a multi-species analysis involving zebrafish and mouse suggests the damage of t-T3 metabolism and signalling as a mechanism of gonadic toxicity of low-doses CPF and ETU. Indeed, the developmental exposure to both compounds reduces Dio2 transcript in both models, as well as in ex-vivo cultures of murine seminiferous tubules, and it is linked to alteration of steroidogenesis and germ cell differentiation. A major impact on spermatogonia was confirmed molecularly by the expression of their markers and morphologically evidenced in zebrafish. The results reveal that in the adopted models, exposure to both pesticides alters the t-T3 metabolism and signalling, affecting the reproductive capability. Our data, together with previous reports suggest zebrafish as an evaluable model in assessing the action of compounds impairing locally T3 signalling.

Development of General Exposure Factors for Risk Assessment in Korean Children

There has been an increasing need for the risk assessment of external environmental hazards in children because they are more sensitive to hazardous chemical exposure than adults. Therefore, the development of general exposure factors is required for appropriate risk assessment in Korean children. This study aimed to determine the general exposure factors among Korean children aged ≤18 years. We developed the recommended exposure factors across five categories: physiological variables, inhalation rates, food and drinking water intake, time-activity patterns, and soil and dust ingestion. National databases were used, and direct measurements and questionnaire surveys of representative samples were performed to calculate the inhalation rate, water intake, and soil ingestion rate. With regard to the time-activity patterns, the daily inhalation rates ranged from 9.49 m3/day for children aged 0-2 years to 14.98 m3/day for those aged 16-18 years. This study found that Korean children spent an average of 22.64 h indoors, 0.63 h outdoors, and 0.73 h in-transit on weekdays. The general exposure factors of Korean children were studied for the first time, and these results could be used to assess children's exposure and risk. They also suggest the differences compared with the results of international results.

Perspective: Cell danger response Biology-The new science that connects environmental health with mitochondria and the rising tide of chronic illness

This paper is written for non-specialists in mitochondrial biology to provide access to an important area of science that has broad implications for all people. The cell danger response (CDR) is a universal response to environmental threat or injury. Once triggered, healing cannot be completed until the choreographed stages of the CDR are returned to an updated state of readiness. Although the CDR is a cellular response, it has the power to change human thought and behavior, child development, physical fitness and resilience, fertility, and the susceptibility of entire populations to disease. Mitochondria regulate the CDR by monitoring and responding to the physical, chemical, and microbial conditions within and around the cell. In this way, mitochondria connect cellular health to environmental health. Over 7,000 chemicals are now made or imported to the US for industrial, agricultural, and personal care use in amounts ranging from 25,000 to over 1 million pounds each year, and plastic waste now exceeds 83 billion pounds/year. This chemical load creates a rising tide of manmade pollutants in the oceans, air, water, and food chain. Fewer than 5% of these chemicals have been tested for developmental toxicity. In the 1980s, 5-10% of children lived with a chronic illness. As of 2018, 40% of children, 50% of teens, 60% of adults under age 65, and 90% of adults over 65 live with a chronic illness. Several studies now report the presence of dozens to hundreds of manmade chemicals and pollutants in placenta, umbilical cord blood, and newborn blood spots. New methods in metabolomics and exposomics allow scientists to measure thousands of chemicals in blood, air, water, soil, and the food chain. Systematic measurements of environmental chemicals can now be correlated with annual and regional patterns of childhood illness. These data can be used to prepare a prioritized list of molecules for congressional action, ranked according to their impact on human health.

Low-Dose Pesticide Mixture Induces Accelerated Mesenchymal Stem Cell Aging In Vitro

The general population is chronically exposed to multiple environmental contaminants such as pesticides. We have previously demonstrated that human mesenchymal stem cells (MSCs) exposed in vitro to low doses of a mixture of seven common pesticides showed a permanent phenotype modification with a specific induction of an oxidative stress-related senescence. Pesticide mixture also induced a shift in MSC differentiation toward adipogenesis. Thus, we hypothesized that common combination of pesticides may induce a premature cellular aging of adult MSCs. Our goal was to evaluate if the prolonged exposure to pesticide mixture could accelerate aging-related markers and in particular deteriorate the immunosuppressive properties of MSCs. MSCs exposed to pesticide mixture, under long-term culture and obtained from aging donor, were compared by bulk RNA sequencing analysis. Aging, senescence, and immunomodulatory markers were compared. The protein expression of cellular aging-associated metabolic markers and immune function of MSCs were analyzed. Functional analysis of the secretome impacts on immunomodulatory properties of MSCs was realized after 21 days' exposure to pesticide mixture. The RNA sequencing analysis of MSCs exposed to pesticide showed some similarities with cells from prolonged culture, but also with the MSCs of an aged donor. Changes in the metabolic markers MDH1, GOT and SIRT3, as well as an alteration in the modulation of active T cells and modifications in cytokine production are all associated with cellular aging. A modified functional profile was found with similarities to aging process. Stem Cells 2019;37:1083-1094.

Prenatal exposure to the herbicide 2,4-D is associated with deficits in auditory processing during infancy

INTRODUCTION

Despite widespread use, many herbicides and fungicides are not well studied for neurological effects. Fetal and infant brains are rapidly developing, yet the effects of early-life exposure to these classes of pesticides on visual and auditory function are unknown. Here we examined the effects of prenatal herbicide and fungicide exposure on infant grating visual acuity (VA) and auditory brainstem response (ABR).

METHODS

9 herbicides and 13 fungicides were measured in umbilical cord blood plasma from a cohort of infants in Fuyang County, China (n = 232). Grating VA and ABR latencies for waves I, III, V were measured at 3 time points: 6 weeks, 9 months, and 18 months. Outcomes included VA score, ABR wave V latency and ABR central conduction time (CCT [wave V- wave I]). Pesticides were analyzed as 3-level ordinal (non-detect [ND]/medium/high), or dichotomous (ND/detect), depending on detection rates. Linear mixed models were used to evaluate relations between pesticides and VA and ABR outcomes.

RESULTS

2,4-dichloroacetic acid (2,4-D), prometryn, simazine, and tetrahydrophthalamide (THPI, a metabolite of captan) were detected in 27%, 81%, 17%, and 16% of samples, respectively. Infants prenatally exposed to 2,4-D had slower auditory response times at 6 weeks. Infants with cord levels of 2,4-D > 1.17 ng/mL had wave V latencies that were 0.12 (95% CI: 0.03, 0.22) ms slower (p = 0.01) and overall CCTs that were 0.15 (95% CI:0.05, 0.25) ms slower (p = 0.003) than infants with non-detectable 2,4-D in their cord blood. No other statistically significant findings were observed for the other herbicides and fungicides or for the grating VA outcome.

CONCLUSIONS

Prenatal exposure to the herbicide 2,4-D was associated with slower auditory signal transmission in early infancy. ABR latencies reflect auditory pathway maturation and longer latencies may indicate delayed auditory development.

Transplacental exposure to carcinogens and risks to children: evidence from biomarker studies and the utility of omic profiling

The factors underlying the increasing rates and the geographic variation of childhood cancers are largely unknown. Epidemiological studies provide limited evidence for a possible role in the etiology of certain types of childhood cancer of the exposure of pregnant women to environmental carcinogens (e.g., tobacco smoke and pesticides); however, such evidence is inadequate to allow definitive conclusions. Complementary evidence can be obtained from biomarker-based population studies. Such studies have demonstrated that, following exposure of pregnant mothers, most environmental carcinogens reach the fetus and, in many cases, induce therein genotoxic damage which in adults is known to be associated with increased cancer risk, implying that environmental carcinogens may contribute to the etiology of childhood cancer. During recent years, intermediate disease biomarkers, obtained via omic profiling, have provided additional insights into the impact of transplacental exposures on fetal tissues which, in some cases, are also compatible with a precarcinogenic role of certain in utero exposures. Here we review the epidemiological and biomarker evidence and discuss how further research, especially utilizing high-density profiling, may allow a better evaluation of the links between in utero environmental exposures and cancer in children.

Prenatal organophosphate insecticide exposure and infant sensory function

BACKGROUND

Occupational studies suggest that exposure to organophosphate insecticides (OPs) can lead to vision or hearing loss. Yet the effects of early-life exposure on visual and auditory function are unknown. Here we examined associations between prenatal OP exposure and grating visual acuity (VA) and auditory brainstem response (ABR) during infancy.

METHODS

30 OPs were measured in umbilical cord blood using gas chromatography tandem mass spectrometry in a cohort of Chinese infants. Grating visual acuity (VA) (n = 179-200) and auditory brainstem response (ABR) (n = 139-183) were assessed at 6 weeks, 9 months, and 18 months. Outcomes included VA score, ABR wave V latency and central conduction time, and head circumference (HC). Associations between sensory outcomes during infancy and cord OPs were examined using linear mixed models.

RESULTS

Prenatal chlorpyrifos exposure was associated with lower 9-month grating VA scores; scores were 0.64 (95% CI: -1.22, -0.06) points lower for exposed versus unexposed infants (p = 0.03). The OPs examined were not associated with infant ABR latencies, but chlorpyrifos and phorate were both significantly inversely associated with HC at 9 months; HCs were 0.41 (95% CI: 0.75, 0.6) cm and 0.44 (95% CI: 0.88, 0.1) cm smaller for chlorpyrifos (p = 0.02) and phorate (p = 0.04), respectively.

CONCLUSIONS

We found deficits in grating VA and HC in 9-month-old infants with prenatal exposure to chlorpyrifos. The clinical significance of these small but statistically significant deficits is unclear. However, the disruption of visual or auditory pathway maturation in infancy could potentially negatively affect downstream cognitive development.

Distribution and predictors of 20 toxic and essential metals in the umbilical cord blood of Chinese newborns

Early-life exposure to heavy metals and/or trace metal imbalances can have negative developmental effects. Here we sought to characterize exposure profiles for 20 heavy metals and trace elements in umbilical cord blood plasma and identify demographic predictors of exposure. Twenty metals were measured in cord plasma from 357 Chinese infants using ICP-MS. Relationships between demographic variables and metals were analyzed using generalized linear models and logistic regression. Ten metals (antimony [Sb], cobalt [Co], cesium [Cs], copper [Cu], lead [Pb], molybdenum [Mo], rubidium [Rb], selenium [Se], strontium [Sr], titanium [Ti], zinc [Zn]) were detected in all samples. Season of birth was the strongest predictor of metals in cord blood across analyses. Infants born in the spring had 0.1-0.2 μg L-1 higher logAs and logCo in their cord blood (β [95%CI] = 0.22 [0.01,0.42], p = 0.04; 0.11 [0.01,0.22], p = 0.04), while infants born in the summer had higher Sb, logB, logHg, and logZn (β [95%CI] = 0.74 [0.24,1.24], p = 0.004; 0.11 [0.00,0.21], p = 0.04; 0.29 [0.08,0.49], p = 0.007; 0.18 [0.06,0.31], p = 0.005), compared to those born in fall/winter. Prenatal heavy metal exposure and/or trace metal deficiencies are global concerns because of increasing awareness of downstream developmental effects.

Poor qualitative analysis of Naled necessarily leads to incorrect quantitative analysis

This correspondence is in regards to a published article, titled "Prenatal Naled and Chlorpyrifos Exposure is Associated with Deficits in Infant Motor Function in a Cohort of Chinese Infants" Silver et al., Environ Int., 2017 Sep; 106:248-256. Upon careful review of this work we identified some significant issues in the mass spectral analysis of naled, specifically its identification and quantification. In this communication we address these issues and provide analytical data and rationale to support our criticism of the reported work. We collected mass spectral data for naled (analytical standard grade) under a variety of mass spectrometric conditions in an attempt to obtain a fragmentation pattern similar to what was reported in Silver et al., 2017. We however, could not reproduce a similar fragmentation pattern under any of the tested experimental conditions. Our results however were in excellent agreement with the National Institute of Standards and Technology (NIST) database, which is a very well established and widely accepted resource for such compounds. This leads us to conclude that naled was in all probability misidentified in the reported (Silver et al., 2017) study which consequently raises serious questions regarding the quantification of naled in the blood samples thus placing the whole statistical correlation of naled as a contributor to impairment of motor function in infants in question.

Prenatal naled and chlorpyrifos exposure is associated with deficits in infant motor function in a cohort of Chinese infants

BACKGROUND

Organophosphate insecticides (OPs) are used worldwide, yet despite nearly ubiquitous exposure in the general population, few have been studied outside the laboratory. Fetal brains undergo rapid growth and development, leaving them susceptible to long-term effects of neurotoxic OPs. The objective here was to investigate the extent to which prenatal exposure to OPs affects infant motor development.

METHODS

30 OPs were measured in umbilical cord blood using gas chromatography tandem mass spectrometry in a cohort of Chinese infants. Motor function was assessed at 6-weeks and 9-months using Peabody Developmental Motor Scales 2nd edition (PDMS-2) (n=199). Outcomes included subtest scores: reflexes, stationary, locomotion, grasping, visual-motor integration (V-M), composite scores: gross (GM), fine (FM), total motor (TM), and standardized motor quotients: gross (GMQ), fine (FMQ), total motor (TMQ).

RESULTS

Naled, methamidophos, trichlorfon, chlorpyrifos, and phorate were detected in ≥10% of samples. Prenatal naled and chlorpyrifos were associated with decreased 9-month motor function. Scores were 0.55, 0.85, and 0.90 points lower per 1ng/mL increase in log-naled, for V-M (p=0.04), FM (p=0.04), and FMQ (p=0.08), respectively. For chlorpyrifos, scores were 0.50, 1.98, 0.80, 1.91, 3.49, 2.71, 6.29, 2.56, 2.04, and 2.59 points lower for exposed versus unexposed infants, for reflexes (p=0.04), locomotion (p=0.02), grasping (p=0.05), V-M (p<0.001), GM (p=0.007), FM (p=0.002), TM (p<0.001), GMQ (p=0.01), FMQ (p=0.07), and TMQ (p=0.008), respectively. Girls appeared to be more sensitive to the negative effects of OPs on 9-month motor function than boys.

CONCLUSIONS

We found deficits in 9-month motor function in infants with prenatal exposure to naled and chlorpyrifos. Naled is being aerially sprayed to combat mosquitoes carrying Zika virus, yet this is the first non-occupational human study of its health effects. Delays in early-motor skill acquisition may be detrimental for downstream development and cognition.

Zebrafish: A Model for the Study of Toxicants Affecting Muscle Development and Function

The rapid progress in medicine, agriculture, and allied sciences has enabled the development of a large amount of potentially useful bioactive compounds, such as drugs and pesticides. However, there is another side of this phenomenon, which includes side effects and environmental pollution. To avoid or minimize the uncontrollable consequences of using the newly developed compounds, researchers seek a quick and effective means of their evaluation. In achieving this goal, the zebrafish (Danio rerio) has proven to be a highly useful tool, mostly because of its fast growth and development, as well as the ability to absorb the molecules diluted in water through its skin and gills. In this review, we focus on the reports concerning the application of zebrafish as a model for assessing the impact of toxicants on skeletal muscles, which share many structural and functional similarities among vertebrates, including zebrafish and humans.

Children's Exposure to Environmental Contaminants: An Editorial Reflection of Articles in the IJERPH Special Issue Entitled, "Children's Exposure to Environmental Contaminants"

Children are at increased vulnerability to many environmental contaminants compared to adults due to their unique behavior patterns, increased contaminant intake per body weight, and developing biological systems. Depending upon their age, young children may crawl on the floor and may practice increased hand to mouth activity that may increase their dose-intake of specific contaminants that accumulate in dust and other matrices. Children are also smaller in size than adults, resulting in a greater body burden for a given contaminant dose. Because children undergo rapid transitions through particular developmental stages they are also especially vulnerable during certain growth-related time windows. A Special Issue was organized focused on the latest findings in the field of children’s environmental exposure for these reasons. This editorial introduces articles in this Special Issue and emphasizes their main findings in advancing the field. From the many articles submitted to this Special Issue from around the world, 23 were accepted and published. They focus on a variety of research areas such as children’s activity patterns, improved risk assessment methods to estimate exposures, and exposures in various contexts and to various contaminants. The future health of a nation relies on protecting the children from adverse exposures and understanding the etiology of childhood diseases. The field of children’s environmental exposures must consider improved and comprehensive research methods aimed at introducing mitigation strategies locally, nationally, and globally. We are happy to introduce a Special Issue focused on children’s environmental exposure and children’s health and hope that it contributes towards improved health of children.