Carbaryl, 1-naphthol and 2-naphthol inhibit the beta-1 thyroid hormone receptor-mediated transcription in vitro

Associations of urinary polycyclic aromatic hydrocarbon (PAH) metabolites and their mixture with thyroid hormone concentration during pregnancy in the LIFECODES cohort: A repeated measures study

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) are endocrine disruptors resulting from incomplete combustion. Pregnancy represents a particularly vulnerable period to such exposures, given the significant influence of hormone physiology on fetal growth and pregnancy outcomes. Maternal thyroid hormones play crucial roles in fetal development and pregnancy outcomes. However, limited studies have examined gestational PAH exposure and maternal thyroid hormones during pregnancy.

METHODS

Our study included 439 women enrolled in the LIFECODES birth cohort in Boston, aiming to explore the relationship between urinary PAH metabolites and thyroid hormones throughout pregnancy. Urine samples for PAH metabolite analysis and plasma samples for thyroid hormone were measured up to four visits throughout gestation. Single pollutant analyses employed linear mixed effect models to investigate individual associations between each PAH metabolite and thyroid hormone concentration. Sensitivity analyses were conducted to assess potential susceptibility windows and fetal-sex-specific effects of PAH exposure. Mixture analyses utilized quantile g-computation to evaluate the collective impact of eight PAH metabolites on thyroid hormone concentrations. Additionally, Bayesian kernel machine regression (BKMR) was employed to explore potential non-linear associations and interactions between PAH metabolites. Subject-specific random intercepts were incorporated to address intra-individual correlation of serial measurements over time in both single pollutant and mixture analyses.

RESULTS

Our findings revealed positive trends in associations between PAH metabolites and thyroid hormones, both individually and collectively as a mixture. Sensitivity analyses indicated that these associations were influenced by the study visit and fetal sex. Mixture analyses suggested non-linear relationships and interactions between different PAH exposures.

CONCLUSIONS

This comprehensive investigation underscores the critical importance of understanding the impact of PAH exposures on thyroid hormone physiology during pregnancy. The findings highlight the intricate interplay between environmental pollutants and human pregnancy physiology, emphasizing the need for targeted interventions and public health policies to mitigate adverse outcomes associated with prenatal PAH exposure.

Urinary polycyclic aromatic hydrocarbon metabolites and hyperlipidemia: NHANES 2007-2016

BACKGROUND

The relationships between urinary polycyclic aromatic hydrocarbon (PAH) metabolites and hyperlipidemia have not been thoroughly studied. The primary goal of this research focused on investigating the linkage between PAH metabolite concentrations in urine and hyperlipidemia prevalence within US adults.

METHODS

A cross-sectional analysis was conducted using data from the 2007-2016 National Health and Nutrition Examination Survey (NHANES). Logistic regression models were used to assess correlations between urinary PAH metabolite levels and the risk of hyperlipidemia, while restricted cubic spline models were used to examine dose‒response relationships. Subgroup and interaction analyses were performed to further elucidate these associations. Weighted quantile sum (WQS) regression analyzed the cumulative impact of various urinary PAH metabolites on hyperlipidemia risk.

RESULTS

This study included 7,030 participants. Notably, individuals in the highest quintile of urinary PAH metabolite concentrations exhibited a significantly elevated prevalence of hyperlipidemia, even after comprehensive adjustments (odds ratio [OR]: 1.33, 95% confidence interval [CI]: 1.01-1.75). Moreover, elevated levels of 1-hydroxyphenanthrene and 2-hydroxynaphthalene in the fourth quintile and 2-hydroxyfluorene in the third, fourth, and fifth quintiles demonstrated positive correlations with the prevalence of hyperlipidemia. These associations persisted across subgroup analyses. Additionally, a positive correlation between the urinary PAH metabolite mixture and hyperlipidemia (positive model: OR = 1.04, 95% CI: 1.00-1.09) was observed in the WQS model, and 2-hydroxynaphthalene showed the most substantial contribution.

CONCLUSION

The cross-sectional analysis identified a significant correlation between urinary PAH metabolite and hyperlipidemia prevalence within the US demographic, with 2-hydroxynaphthalene being the predominant influencer. These findings underscore the need to mitigate PAH exposure as a preventive measure for hyperlipidemia.

Application of the Key Characteristics of Carcinogens to Bisphenol A

The ten key characteristics (KCs) of carcinogens are based on characteristics of known human carcinogens and encompass many types of endpoints. We propose that an objective review of the large amount of cancer mechanistic evidence for the chemical bisphenol A (BPA) can be achieved through use of these KCs. A search on metabolic and mechanistic data relevant to the carcinogenicity of BPA was conducted and web-based software tools were used to screen and organize the results. We applied the KCs to systematically identify, organize, and summarize mechanistic information for BPA, and to bring relevant carcinogenic mechanisms into focus. For some KCs with very large data sets, we utilized reviews focused on specific endpoints. Over 3000 studies for BPA from various data streams (exposed humans, animals, in vitro and cell-free systems) were identified. Mechanistic data relevant to each of the ten KCs were identified, with receptor-mediated effects, epigenetic alterations, oxidative stress, and cell proliferation being especially data rich. Reactive and bioactive metabolites are also associated with a number of KCs. This review demonstrates how the KCs can be applied to evaluate mechanistic data, especially for data-rich chemicals. While individual entities may have different approaches for the incorporation of mechanistic data in cancer hazard identification, the KCs provide a practical framework for conducting an objective examination of the available mechanistic data without a priori assumptions on mode of action. This analysis of the mechanistic data available for BPA suggests multiple and inter-connected mechanisms through which this chemical can act.

Brain-derived neurotrophic factor (BDNF): an effect biomarker of neurodevelopment in human biomonitoring programs

The present narrative review summarizes recent findings focusing on the role of brain-derived neurotrophic factor (BDNF) as a biomarker of effect for neurodevelopmental alterations during adolescence, based on health effects of exposure to environmental chemical pollutants. To this end, information was gathered from the PubMed database and the results obtained in the European project Human Biomonitoring for Europe (HBM4EU), in which BDNF was measured at two levels of biological organization: total BDNF protein (serum) and BDNF gene DNA methylation (whole blood) levels. The obtained information is organized as follows. First, human biomonitoring, biomarkers of effect and the current state of the art on neurodevelopmental alterations in the population are presented. Second, BDNF secretion and mechanisms of action are briefly explained. Third, previous studies using BDNF as an effect biomarker were consulted in PubMed database and summarized. Finally, the impact of bisphenol A (BPA), metals, and non-persistent pesticide metabolites on BDNF secretion patterns and its mediation role with behavioral outcomes are addressed and discussed. These findings were obtained from three pilot studies conducted in HBM4EU project. Published findings suggested that exposure to some chemical pollutants such as fine particle matter (PM), PFAS, heavy metals, bisphenols, and non-persistent pesticides may alter circulating BDNF levels in healthy population. Therefore, BDNF could be used as a valuable effect biomarker to investigate developmental neurotoxicity of some chemical pollutants.

Urine 2-hydroxyphenanthrene is associated with current asthma: evidence from NHANES 2007-2012

OBJECTIVE

The current study aims to explore the effects of nine urine monohydroxy PAH metabolites (OHPAH) including 1-hydroxynaphthalene (1-OHNAP), 2-hydroxynaphthalene (2-OHNAP), 3-hydroxyfluorene (3-OHFLU), 9-hydroxyfluorene (9-OHFLU), 1-hydroxyphenanthrene (1-OHPHE), 2-hydroxyphenanthrene (2-OHPHE), 3-hydroxyphenanthrene (3-OHPHE), and 1-hydroxypyrene (1-OHPYR) on current asthma in people in the United States using a variety of statistical techniques.

METHODS

A cross-sectional examination of a subsample of 3804 adults aged ≥20 from the National Health and Nutrition Examination Survey (NHANES) was conducted between 2007 and 2012. To investigate the relationship between urine OHPAHs levels and current asthma, multivariate logistic regression, Bayesian kernel machine regression (BKMR), and quantile g-computation (qgcomp) were utilized.

RESULTS

In the multivariate logistic regression model, after controlling for confounders, urine 2-OHPHE was associated with current asthma in both male (AOR = 7.17, 95% CI: 1.28-40.08) and female (AOR = 2.91, 95% CI: 1.06-8.01) smokers. In the qgcomp analysis, 2-OHPHE (39.5%), 1-OHNAP (33.1%), and 2-OHNAP (22.5%) were the major positive contributors to the risk of current asthma (OR = 2.29, 95% CI: 0.99, 5.25), and in female smokers, 9-OHFLU (25.8%), 2-OHFLU (21.5%), and 2-OHPHE (15.1%) were the major positive contributors (OR = 2.19, 95% CI: 1.06, 4.47). The results of the BKMR model basically agreed with qgcomp analysis.

CONCLUSION

Our results demonstrate a strong association of urine 2-OHPHE with current asthma, and further longitudinal studies are needed to understand the precise relationship between PAH exposure and current asthma risk.

Urinary concentrations of polycyclic aromatic hydrocarbon metabolites and childhood obesity

Objectives

Existing literature provides limited information on the association between childhood obesity and polycyclic aromatic hydrocarbons (PAHs), which are potentially obesogenic. We examined the association between urinary concentrations of PAH metabolites and obesity in the Korean pediatric population.

Methods

We analyzed the data of 2286 children/adolescents aged 3-17 years who participated in the Korean National Environmental Health Survey between 2015 and 2017. Urinary concentrations of 2-naphthol, 2-hydroxyfluorene, 1-hydroxyphenanthrene, and 1-hydroxypyrene were assayed using gas chromatography-mass spectrometry. Overweight/obesity was defined as a body mass index (BMI) for age ≥85th percentile. Multiple linear and logistic regression models were used to analyze the relationship of BMI z-score and overweight with urinary concentrations of PAH metabolites after adjusting for age, sex, household income, parental education level, physical activity, fast-food consumption, and environmental tobacco smoke exposure.

Results

BMI z-score was positively associated with 2-naphthol concentrations in children aged 6-11 and 12-17 years and with 1-hydroxypyrene concentrations in children aged 6-11 years. In the overall population, a significant rise in odds ratios for overweight/obesity across 2-naphthol quartiles was noted. Specifically, the 3rd and 4th quartiles displayed odds ratios of 1.39 [1.03, 1.88] and 1.46 [1.08, 1.99] respectively, compared to the 1st quartile (P-for-trend = 0.006). Similar associations between 2-naphthol and overweight/obesity status were observed in the 6-11- and 12-17-year age groups. There was little evidence of an association between overweight/obesity and other PAH hydroxy derivatives.

Conclusions

PAH exposure may be associated with increased childhood adiposity, a potential risk factor for adult obesity and adverse metabolic outcomes.

Associations between prenatal exposure to polycyclic aromatic hydrocarbons and thyroid hormones in umbilical cord blood

We explored the association between maternal urinary polycyclic aromatic hydrocarbon (PAH) metabolites and thyroid hormones in umbilical cord blood in 120 pairs of pregnant women and newborns. Maternal urinary PAH metabolites were measured using high-performance liquid chromatography with tandem mass spectrometry. Thyroid hormones were measured using a flow fluorescence assay. The dose-response relationship between PAH metabolites and thyroid hormones was analyzed using the generalized linear model and restricted cubic spline model. Results showed that ƩOH PAHs in maternal urine had a negative effect on triiodothyronine (T3). Associations between maternal urinary PAH metabolites and thyroid hormones in umbilical cord blood plasma were observed. Prenatal exposure to PAHs could affect neonatal thyroid hormones, thereby disrupting neonatal thyroid function.

Association between polycyclic aromatic hydrocarbon exposure and hypertension among the U.S. adults in the NHANES 2003-2016: A cross-sectional study

The global burden of hypertension, the major cause of cardiovascular disease (CVD) globally, remains unresolved. Exposure to PM2.5 has been linked to hypertension (HTN) in adults and the elderly globally according to previous studies. Nonetheless, evidence on the association of polycyclic aromatic hydrocarbon (PAH) exposure and HTN risk in the general adult population in the United States was limited. To investigate the relationship between PAH exposure and HTN in adults in the United States, cross-sectional data during 2003 and 2016 from the National Health and Nutrition Examination Survey (NHANES) on a stratified multistage random sample of the civilian non-institutionalized population were utilized. After eliminating individuals with incomplete information of interest, the final analysis contained 8951 subjects aged ≥20. In the multivariate logistic regression model, 1-hydroxynaphthalene and 2-hydroxyfluorene were found positively associated with increased risk of HTN among overall participants after adjusting for the covariates. 1-hydroxynaphthalene and 2-hydroxynaphthalene showed positive associations with HTN risk among overweight participants. In the Bayesian kernel machine regression (BKMR) model, 1-hydroxynaphthalene and 2-hydroxyfluorene presented great importance to HTN risk among overall individuals. In the male subgroup analyses by BKMR, 2-hydroxyfluorene presented a positive effect on HTN risk when the remaining OH-PAHs were set at their 25th, 50th, and 75th percentile. Our findings highlight the complexities of estimating the risk of HTN associated with mixed PAH exposure, and additional longitudinal studies are required to determine the exact link between PAH exposure and HTN risk, as well as the underlying mechanisms.

Co-inducible Catabolism of 2-Naphthol Initiated by Hydroxylase CehC1C2 in Rhizobium sp. X9 Removed Its Ecotoxicity

2-Naphthol, which originates from various industrial activities, is widely disseminated through the discharge of industrial wastewater and is, thus, harmful to the water ecosystem, agricultural production, and human health. In this study, the carbaryl degrading strain Rhizobium sp. X9 was proven to be able to degrade 2-naphthol and reduce its toxicity to rice (Oryza sativa) and Chlorella ellipsoidea. Two-component hydroxylase CehC1C2 is responsible for the initial step of degradation and generates 1,2-dihydroxynaphthalene, which is further degraded by the ceh cluster. The transcription of gene cluster cehC1C2 could be induced when both 2-naphthol and glucose were added. A bioinformatic analysis revealed that two transcriptional regulators, the inhibitor CehR2 and the activator CehR3, could be involved in this process. Our study elucidated the molecular mechanism of microbial degradation of 2-naphthol and provided an effective strategy for the in situ remediation of 2-naphthol contamination in the environment.

Associations between repeated measurements of urinary polycyclic aromatic hydrocarbon metabolites and thyroid hormones among reproductive-aged men

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) have been shown to disrupt thyroid function in toxicological studies, but epidemiological evidence is inconsistent. Furthermore, little is known on potential effects of mixtures of PAHs.

OBJECTIVE

This study aimed to examine the associations of exposure to PAHs as individual chemicals and mixtures with thyroid hormones.

METHODS

We included 378 men from a Reproductive Medicine Center in Wuhan, China. Ten monohydroxylated PAH (OH-PAH) metabolites in repeated urine specimens collected at two-time points and three thyroid hormones [thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3)] in one serum sample were measured. Multivariable linear regression models were applied to assess the associations between individual OH-PAH metabolites and thyroid hormones, and the associations with mixtures of OH-PAH metabolites were assessed by Bayesian kernel machine regression (BKMR) models.

RESULTS

Multivariable linear regression models showed inverse associations between urinary 1-OHNa and TSH, between urinary 1-OHPh and 9-OHPh and FT3, as well as between urinary 2-OHPh, 3-OHPh, 9-OHPh and ∑OHPh and FT4, regardless of these individual OH-PAH metabolites modeled as continuous or tertile variables (e.g., -21.57 % in TSH; 95 % CI: -35.33 %, -4.88 % for the third vs first tertiles of 1-OHNa; p for trend = 0.014). BKMR models showed negative overall effects of all urinary OH-PAH metabolite mixtures on TSH, FT3, and FT4, and 1-OHNa, 9-OHPh, and 2-OHPh as the most important contributors, respectively, with linear inverse exposure-response associations when holding other OH-PAH metabolites at their median concentrations.

CONCLUSION

Urinary OH-PAH metabolites as individual chemicals and mixtures were adversely associated with thyroid hormones among reproductive-aged men.

Thyroid Carcinoma: A Review for 25 Years of Environmental Risk Factors Studies

Environmental factors are established contributors to thyroid carcinomas. Due to their known ability to cause cancer, exposure to several organic and inorganic chemical toxicants and radiation from nuclear weapons, fallout, or medical radiation poses a threat to global public health. Halogenated substances like organochlorines and pesticides can interfere with thyroid function. Like phthalates and bisphenolates, polychlorinated biphenyls and their metabolites, along with polybrominated diethyl ethers, impact thyroid hormones biosynthesis, transport, binding to target organs, and impair thyroid function. A deeper understanding of environmental exposure is crucial for managing and preventing thyroid cancer. This review aims to investigate the relationship between environmental factors and the development of thyroid cancer.

Measurement of hair thyroid and steroid hormone concentrations in the rat evidence endocrine disrupting potential of a low dose mixture of polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) have been shown to influence endogenous hormones levels in animal models, but little is known about the effects of their mixtures. For hormone measurements, hair analysis is a promising approach to provide information on long-term status of hormones. Herein we used hair analysis to assess the combined effects of 13 PAHs on steroid and thyroid hormones levels in a rat model. The PAH mixture was administered orally three times per week to female rats at doses of 0, 10, 20, 40, 80, 200, 400 and 800 μg/kg of body weight for each compound over a 90-day exposure period. Fourteen out of 36 analyzed hormones were detected in rat hair, including pregnenolone (P5), 17α-hydroxyprogesterone (17-OHP4), corticosterone (CORT), dehydroepiandrosterone (DHEA), androstenedione (AD), 3,3'-diiodo-L-thyronine (T2), 3,3',5-triiodo-L-thyronine (T3), and 3,5,3',5'-triiodo-L-thyronine (T4). The PAH mixture significantly elevated P5 and DHEA levels at the doses of 200 and 400 μg/kg but reduced T2 and T3 levels at the highest dose as compared to the control. While P5, DHEA, 17-OHP4 and AD concentrations exhibited inverted U-shaped dose responses, T2, T3 and T4 concentrations exhibited inverse linear dose responses, which are further confirmed by their relationships with hair hydroxylated PAHs (OH-PAHs) concentrations. Likewise, there were significant nonmonotonic relationships of hormone molar ratios (e.g., AD/17-OHP4 and DHEA/CORT ratios) with exposure intensity and OH-PAHs. Overall, our results demonstrate the capability of PAH mixtures to interfere with steroid and thyroid hormones in female rats.

Urinary polycyclic aromatic hydrocarbon metabolites were associated with hypertension in US adults: data from NHANES 2009-2016

Polycyclic aromatic hydrocarbons (PAHs) are widely existing organic pollutants in the environment, and their persistence in the environment makes us have to pay continuous attention to their health effects. However, since the American Heart Association updated its definition of hypertension in 2017, few studies have explored the relationship. This study aimed to investigate the relationship between PAH exposure and hypertension after the updated definition of hypertension and explore whether body mass index (BMI) moderates this relationship. A total of 6332 adult participants from the 2009-2016 National Health and Nutrition Examination Survey (NHANES) were examined. Multiple logistic regression and restricted cubic splines were used to analyze the association between urinary polycyclic aromatic hydrocarbon metabolites and hypertension, and the dose-response relationship. Weighted quantile sum (WQS) regression was applied to blood pressure to reveal multiple exposure effects and the relative weights of each PAH. The prevalence of hypertension in the study population was 48.52%. There was a positive dose-response relationship between high exposure to 1-hydroxynaphthalene, 2&3-hydroxyphenanthrene, and the risk of hypertension. Naphthalene metabolites accounted for the most significant proportion of systolic blood pressure, and phenanthrene metabolites accounted for the most significant proportion of diastolic blood pressure. Obese individuals with high PAH exposure were at greater risk for hypertension than individuals with low PAH exposure and normal BMI. Higher prevalence rate and stronger association of metabolites with outcomes were obtained in the general population of the USA under the new guideline. High levels of exposure to PAHs were positively associated with the risk of hypertension, and these effects were modified by BMI.

Urinary polycyclic aromatic hydrocarbon excretion and regional body fat distribution: evidence from the U.S. National Health and Nutrition Examination Survey 2001-2016

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants that may contribute to the etiology of obesity. However, it is unclear whether PAHs from environmental sources are associated with regional body fat distribution, and whether the association varies across racial/ethnic groups who may have differential PAH exposure patterns.

OBJECTIVES

To examine correlations between PAHs and body fat distribution, and potential racial/ethnic differences among U.S. adults.

METHODS

Ten PAHs were measured in spot urine samples from 2691 non-smoking adults (age ≥ 20 years) in the NHANES 2001-2016. Dual-energy X-ray absorptiometry was used to measure fat mass percent (FM%). Partial Pearson correlation coefficients (r) with multivariable adjustment were used to assess PAH-FM% associations.

RESULTS

In the total population, 1-naphthalene, 3-fluorene, and 1-pyrene were inversely correlated with total FM% or trunk FM% (adjusted r ranged: - 0.06 to - 0.08), while 2-naphthalene, 9-fluorene, and 4-phenanthrene were positively correlated with the FM% measurements (r: 0.07-0.11). PAH levels are highest among non-Hispanic Blacks, followed by Hispanics and Whites and some of the correlations were different by these races/ethnicities. Among non-Hispanic Whites, no PAH was correlated with FM%. In contrast, 9-fluorene was positively correlated with total FM% (r = 0.20) and trunk FM% (r = 0.22) among Blacks, and 4-phenanthrene was positively correlated with total FM% (r = 0.23) and trunk FM% (r = 0.24) among Hispanics (P-interaction: 0.010-0.025).

DISCUSSION

In this US adult population, certain PAHs are significantly associated with higher body fat contents among non-Hispanic Blacks and Hispanics but not non-Hispanic Whites, suggesting that minority groups might be particularly susceptible to PAH's obesogenic effects or the effects of other factors that determine the PAH exposure levels. Alternatively, differences in body composition may contribute to differential PAH metabolism in minority groups. Future studies are warranted to explore the racial/ethnic disparity in PAH exposures, drivers of these exposure differences, and mechanisms through which PAHs may influence body composition by races/ethnicities.

Exposure to non-persistent pesticides, BDNF, and behavioral function in adolescent males: Exploring a novel effect biomarker approach

BACKGROUND

Numerous contemporary non-persistent pesticides may elicit neurodevelopmental impairments. Brain-derived neurotrophic factor (BDNF) has been proposed as a novel effect biomarker of neurological function that could help to understand the biological responses of some environmental exposures.

OBJECTIVES

To investigate the relationship between exposure to various non-persistent pesticides, BDNF, and behavioral functioning among adolescents.

METHODS

The concentrations of organophosphate (OP) insecticide metabolites 3,5,6-trichloro-2-pyridinol (TCPy), 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMPy), malathion diacid (MDA), and diethyl thiophosphate (DETP); metabolites of pyrethroids 3-phenoxybenzoic acid (3-PBA) and dimethylcyclopropane carboxylic acid (DCCA), the metabolite of insecticide carbaryl 1-naphthol (1-N), and the metabolite of ethylene-bis-dithiocarbamate fungicides ethylene thiourea (ETU) were measured in spot urine samples, as well as serum BDNF protein levels and blood DNA methylation of Exon IV of BDNF gene in 15-17-year-old boys from the INMA-Granada cohort in Spain. Adolescents' behavior was reported by parents using the Child Behavior Check List (CBCL/6-18). This study included 140 adolescents of whom 118 had data on BDNF gene DNA methylation. Multivariable linear regression, weighted quantile sum (WQS) for mixture effects, and mediation models were fit.

RESULTS

IMPy, MDA, DCCA, and ETU were detected in more than 70% of urine samples, DETP in 53%, and TCPy, 3-PBA, and 1-N in less than 50% of samples. Higher levels of IMPy, TCPy, and ETU were significantly associated with more behavioral problems as social, thought problems, and rule-breaking symptoms. IMPy, MDA, DETP, and 1-N were significantly associated with decreased serum BDNF levels, while MDA, 3-PBA, and ETU were associated with higher DNA methylation percentages at several CpGs. WQS models suggest a mixture effect on more behavioral problems and BDNF DNA methylation at several CpGs. A mediated effect of serum BDNF within IMPy-thought and IMPy-rule breaking associations was suggested.

CONCLUSION

BDNF biomarkers measured at different levels of biological complexity provided novel information regarding the potential disruption of behavioral function due to contemporary pesticides, highlighting exposure to diazinon (IMPy) and the combined effect of IMPy, MDA, DCCA, and ETU. However, further research is warranted.

Urinary levels of monohydroxylated polycyclic aromatic hydrocarbons in Brazilian children and health risk assessment: a human biomonitoring-based study

Monitoring human exposure to polycyclic aromatic hydrocarbons (PAHs) is a public health concern. Children are a vulnerable subgroup of the population with limited human biomonitoring data worldwide. Thus, this study aimed to measure the levels of seven PAH metabolites in urine from Brazilian children and provide risk assessment values for this exposure. Our data show naphthalene was the major contributor to children's exposure to PAHs, with a 100% detection rate. Children in urban regions presented higher exposure to PAHs, with higher concentrations of 2-naphthol in the southeast (1.09 ng/mL, p < 0.05). Furthermore, the highest concentration of 2-naphthol was found in older children (p = 0.02), suggesting a possible difference in dietary habits. Exposure to the carbaryl insecticide is suggested based on the high concentrations of 1-naphthol (1.29 ng/mL) and considering the ratio 1-naphthol/2-naphthol (1.78). Moreover, the positive correlation between the metabolites of fluorine and pyrene also suggests exposure to PAHs by petrol combustion. The risk assessment of the PAH exposure was evaluated using the estimated daily intake (EDI) for two naphthalene metabolites in the study with a 100% detection rate. The EDI was 14.47 ng/kg BW/day. The risk assessment to the PAH exposure revealed a non-carcinogenic risk profile, with a hazard quotient of 0.71. To the best of our knowledge, this study is the first to provide levels of PAHs in Brazilian children.

Next-generation biomonitoring of the early-life chemical exposome in neonatal and infant development

Exposure to synthetic and natural chemicals is a major environmental risk factor in the etiology of many chronic diseases. Investigating complex co-exposures is necessary for a holistic assessment in exposome-wide association studies. In this work, a sensitive liquid chromatography-tandem mass spectrometry approach was developed and validated. The assay enables the analysis of more than 80 highly-diverse xenobiotics in urine, serum/plasma, and breast milk; with detection limits generally in the pg-ng mL⁻¹ range. In plasma of extremely-premature infants, 27 xenobiotics are identified; including contamination with plasticizers, perfluorinated alkylated substances and parabens. In breast milk samples collected longitudinally over the first 211 days post-partum, 29 analytes are detected, including pyrrolizidine- and tropane alkaloids which have not been identified in this matrix before. A preliminary estimation of daily toxicant intake via breast milk is conducted. In conclusion, we observe significant early-life co-exposure to multiple toxicants, and demonstrate the method’s applicability for large-scale exposomics-type cohort studies.

Exposure to synthetic and natural toxicants is a major risk factor in the etiology of disease. Here, authors describe the development of a method to quantify >80 xenobiotics and apply it to assess early-life exposure in vulnerable infants.

Prenatal exposure to polycyclic aromatic hydrocarbons and effects on neonatal anthropometric indices and thyroid-stimulating hormone in a Middle Eastern population

Prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) evokes extensive concerns regarding public health. Monitoring the pregnant women's exposure can be considered a suitable alternative to assess the fetus's exposure. This study aimed to monitor pregnant women's exposure (n = 126) to PAHs using a biomonitoring approach to evaluate effects on anthropometric indices and neonatal thyroid-stimulating hormone (TSH) in Shiraz, Iran. PAHs priority compounds were measured by gas chromatography-mass spectrometry (GC-MS) after separating blood serum and liquid-liquid extraction (LLE) method. Information on anthropometric indices, neonatal TSH levels, and data from the respondents was obtained from medical records and questionnaires. The mean PAHs concentrations ranged from 0.29 to 327.91 ng/g lipid. There was no significant difference between the measured PAHs in maternal serum at the seventh month and pregnancy termination except for ACY (p-Value<0.05). Regression analysis results showed a significant correlation (p-value<0.05) between exposure to passive smoke and total PAHs concentrations. There was no significant relationship between exposure to PAHs and weight, height, head circumference, and Apgar score of newborns. The results showed TSH decreased by 0.99 units as ACE increased per unit (β = -0.001). This study is the first to evaluate relationships between prenatal exposure to PAHs and effects on newborn health indicators, including TSH levels in a Middle Eastern population. Future studies are suggested to perform detailed assessments of PAHs intake sources, especially in vulnerable populations such as pregnant women and children.

The association between urinary metabolites of polycyclic aromatic hydrocarbons (PAHs) and cardiovascular diseases and blood pressure: a systematic review and meta-analysis of observational studies

Although epidemiological studies have discerned the association between polycyclic aromatic hydrocarbons (PAHs) exposure and hypertension and/or cardiovascular disease in the general population, the possible mechanisms for this association are not well understood. We sought to examine the association between urinary metabolites of PAHs and cardiovascular diseases (CVDs) and blood pressure in adults, by conducting a meta-analysis of observational studies. We searched PubMed, Scopus, Embase, and Web of science, up to July 2021, for observational studies that investigated the association between urinary metabolites of PAHs and CVDs and blood pressure in adults. Nine prospective studies, including 27,280 participants, were included. Based on overall pooled results, there was a significant positive association between all types of urinary metabolites of PAH and blood pressure (OR: 1.32; 95%, CI: 1.19 to 1.48, p < 0.0001) (I² = 62.4%, p < 0.0001). There was no significant association between any urinary metabolite of PAH and CHD (OR: 0.93; 95%, CI: 0.83 to 1.03, p = 0.174) (I² = 0%, p = 0.653). Overall, there was a significant positive association between all urinary metabolites of PAH and CVD (OR: 1.23; 95%, CI: 1.16 to 1.30, p < 0.0001) (I² = 59.7%, p < 0.0001). The results of the present meta-analysis suggest that different metabolites PAHs are associated with an increased risk of CVD and HTN. Further studies, including randomized clinical trials, are needed to confirm the veracity of our findings.

Urinary metabolites of non-persistent pesticides and serum hormones in Spanish adolescent males

OBJECTIVE

To assess the relationship of urinary concentrations of ethylenethiourea (ETU), the main degradation product of ethylene bis-dithiocarbamate fungicides, 3-phenoxybenzoic acid (3-PBA), a common metabolite of many pyrethroids, and 1-naphthol (1N), a metabolite of the carbamate insecticide carbaryl, with hormone concentrations in adolescent males; and to examine interactions between pesticide metabolites and polymorphisms in xenobiotic metabolizing enzymes, including CYP2C19 and CYP2D6, in relation to hormone concentrations.

METHODS

A cross-sectional study was conducted in 134 males from the Spanish Environment and Childhood (INMA)-Granada cohort. Urine and serum samples were collected from participants during the same clinical visit at the age of 15-17 years. First morning urine void was analyzed for concentrations of ETU, 3-PBA, and 1N. Serum was analyzed for concentrations of reproductive hormones (testosterone, 17β-estradiol [E₂], dehydroepiandrosterone sulfate [DHEAS], sex hormone binding globulin [SHBG], luteinizing hormone [LH], follicle stimulating hormone [FSH], anti-Müllerian hormone [AMH], and prolactin), thyroid hormones (free thyroxine [FT4], total triiodothyronine [TT3], and thyroid stimulating hormone [TSH]), insulin growth factor 1 (IGF-1), adrenocorticotropic hormone (ACTH), and cortisol. CYP2C19 G681A and CYP2D6 G1846A polymorphisms were determined in blood from 117 participants. Multiple linear regression, interaction terms, and stratified analyses were performed.

RESULTS

Urinary ETU was detected in 74.6% of participants, 1N in 38.1%, and 3-PBA in 19.4%. Positive associations between detectable 3-PBA and TT3 and between detectable 1N and DHEAS were found, and marginally-significant associations of 1N with reduced E₂ and FSH were observed. Poor CYP2C19 and CYP2D6 metabolizers (GA and AA genotype carriers) showed a greater increase in DHEAS for detected versus undetected 1N compared with GG genotype carriers. Poor CYP2D6 metabolizers (1846 GA and AA genotypes) evidenced increased cortisol for detected versus undetected ETU.

CONCLUSIONS

The associations observed between urinary pesticide metabolites and altered thyroid and reproductive hormones are novel and should be verified in studies with larger sample size. Further research on gene-environment interactions is warranted to establish individual susceptibility to pesticides and the risk of adverse health effects.

Thyroid disrupting effects of low-dose dibenzothiophene and cadmium in single or concurrent exposure: New evidence from a translational zebrafish model

Thyroid hormones (THs) are major regulators of biological processes essential for correct development and energy homeostasis. Although thyroid disruptors can deeply affect human health, the impact of exogenous chemicals and in particular mixture of chemicals on different aspects of thyroid development and metabolism is not yet fully understood. In this study we have used the highly versatile zebrafish model to assess the thyroid axis disrupting effects of cadmium (Cd) and dibenzothiophene (DBT), two environmental endocrine disruptors found to be significantly correlated in epidemiological co-exposure studies. Zebrafish embryos (5hpf) were exposed to low concentrations of Cd (from 0.05 to 2 μM) and DBT (from 0.05 to 1 μM) and to mixtures of them. A multilevel assessment of the pollutant effects has been obtained by combining in vivo morphological analyses allowed by the use of transgenic fluorescent lines with liquid chromatography mass spectrometry determination of TH levels and quantification of the expression levels of key genes involved in the Hypothalamic-Pituitary-Thyroid Axis (HPTA) and TH metabolism. Our results underscore for the first time an important synergistic toxic effect of these pollutants on embryonic development and thyroid morphology highlighting differences in the mechanisms through which they can adversely impact on multiple physiological processes of the HPTA and TH disposal influencing also heart geometry and function.

Coinducible Catabolism of 1-Naphthol via Synergistic Regulation of the Initial Hydroxylase Genes in Sphingobium sp. Strain B2

1-Naphthol, a widely used raw material for organic synthesis, is also a well-known organic pollutant. Due to its high toxicity, 1-naphthol is rarely used by microorganisms as the sole carbon source for growth. In this study, catabolism of 1-naphthol by Sphingobium sp. strain B2 was found to be greatly enhanced by additional supplementation with primary carbon sources (e.g., glucose, maltose, and sucrose), and 1-naphthol was even used as the carbon source for growth when strain B2 cells had been preinduced by both 1-naphthol and glucose. A distinct two-component flavin-dependent monooxygenase, NdcA1A2, was found to be responsible for the initial hydroxylation of 1-naphthol to 1,2-dihydroxynaphthalene, a more toxic compound. Transcriptional levels of ndcA1A2 genes were significantly upregulated when strain B2 cells were cultured with both 1-naphthol and glucose compared to cells cultured with only 1-naphthol or glucose. Two transcriptional regulators, the activator NdcS and the inhibitor NdcR, were found to play key roles in the synergistic regulation of the transcription of the 1-naphthol initial catabolism genes ndcA1A2 IMPORTANCE Cometabolism is a widely observed phenomenon, especially in the field of microbial catabolism of highly toxic xenobiotics. However, the mechanisms of cometabolism are ambiguous, and the roles of the obligately coexisting growth substrates remain largely unknown. In this study, we revealed that the roles of the coexisting primary carbon sources (e.g., glucose) in the enhanced catabolism of the toxic compound 1-naphthol in Sphingobium sp. strain B2 were not solely because they were used as growth substrates to support cell growth but, more importantly, because they acted as coinducers to interact with two transcriptional regulators, the activator NdcS and the inhibitor NdcR, to synergistically regulate the transcription of the 1-naphthol initial catabolism genes ndcA1A2 Our findings provide new insights into the cometabolic mechanism of highly toxic compounds in microorganisms.

Pesticide exposure and incident thyroid cancer among male pesticide applicators in agricultural health study

BACKGROUND

Many pesticides are known to have thyroid-disrupting properties. However, few studies have evaluated the association between specific pesticide ingredients and risk of thyroid cancer. We investigated self-reported pesticide use and incident thyroid cancer in the Agricultural Health Study (AHS), a large cohort of occupationally-exposed male pesticide applicators.

METHODS

The AHS is a prospective cohort of licensed pesticide applicators in Iowa and North Carolina. At enrollment (1993-1997) and follow-up (1999-2005), participants reported use of 50 pesticides. We characterized exposure as ever use (44 pesticides with ≥5 exposed cases) and by cumulative intensity-weighted lifetime days (22 pesticides with ≥10 exposed cases), a metric that accounts for factors that influence exposure. We estimated hazard ratios (HR) and 95% confidence intervals (CI) using Cox regression for incident thyroid (n = 85 cases) cancer among male participants using follow-up through 2014/2015.

RESULTS

Use of the fungicide metalaxyl (HR = 2.03, CI:1.16-3.52) and the organochlorine insecticide lindane (HR = 1.74, CI:1.06-2.84) was associated with increased risk of thyroid cancer. The herbicide chlorimuron-ethyl was inversely associated with risk when we restricted to papillary thyroid cancer, the most common subtype (HR = 0.52, CI:0.28-0.96). High use of the insecticide carbaryl (>median intensity-weighted days) was inversely associated with thyroid cancer (HR = 0.20, CI:0.08-0.53, p_trend = 0.001).

CONCLUSIONS

In this large cohort study, we observed increased risk of thyroid cancer associated with use of metalaxyl and lindane, and an inverse association with carbaryl. More work is needed to understand the potential role of these chemicals in thyroid carcinogenesis.

Association between urinary polycyclic aromatic hydrocarbons and hypertension in the Korean population: data from the Second Korean National Environmental Health Survey (2012-2014)

Polycyclic aromatic hydrocarbons (PAHs) are environmental and occupational pollutants derived from incomplete combustion of organic materials, including wood and fossil fuels. Epidemiological studies have evaluated the association between PAH exposure and hypertension or cardiovascular disease in the general population, but the evidence is limited. In this study, we evaluated the association between urinary PAH metabolites and hypertension in the Korean adult population. A total of 6478 adults who participated in the Second Korean National Environmental Health Survey (2012–2014) were included. The differences in urinary concentrations of four PAH metabolites, including 1-hydroxypyrene, 2-hydroxyfluorene, 1-hydroxyphenanthrene, and 2-naphthol, were compared according to hypertension status using a general linear model. Adjusted odds ratios (aORs) for hypertension were calculated according to the quartile groups of urinary PAH metabolites after adjusting for age, sex, body mass index (BMI), smoking, and alcohol consumption in multiple logistic regression analyses. The estimated mean concentrations of urinary 1-hydroxyphenanthrene were significantly higher in the hypertension group than in the non-hypertension group. In 1-hydroxyphenanthrene, the OR for hypertension was significantly higher in the third and fourth quartile groups than in the first quartile group (third: OR 1.707, 95% CI 1.203–2.423, fourth: OR 1.604, 95% CI 1.158–2.223). No significant associations were detected for the other metabolites. Our results suggest an association between exposure to PAHs and hypertension in a Korean adult population. Further studies are required to evaluate the effects of low-dose long-term exposure to PAHs on hypertension and cardiovascular disease.

Urinary polycyclic aromatic hydrocarbons in relation to anthropometric measures and pubertal development in a cohort of Northern California girls

Supplemental Digital Content is available in the text.

Polycyclic aromatic hydrocarbons (PAHs) are a class of ubiquitous, environmental chemicals that may have endocrine disrupting capabilities. We investigated whether childhood exposure to PAHs was associated with adiposity and pubertal timing in a longitudinal study of 404 girls enrolled in the Northern California site of the Breast Cancer and the Environment Research Program cohort.

Association of Exposure to Ambient Air Pollution With Thyroid Function During Pregnancy

IMPORTANCE

Air pollutants interact with estrogen nuclear receptors, but their effect on thyroid signaling is less clear. Thyroid function is of particular importance for pregnant women because of the thyroid's role in fetal brain development.

OBJECTIVE

To determine the short-term association of exposure to air pollution in the first trimester with thyroid function throughout pregnancy.

DESIGN, SETTING, AND PARTICIPANTS

In this cohort study, 9931 pregnant women from 4 European cohorts (the Amsterdam Born Children and Their Development Study, the Generation R Study, Infancia y Medio Ambiente, and Rhea) and 1 US cohort (Project Viva) with data on air pollution exposure and thyroid function during pregnancy were included. The recruitment period for the Amsterdam Born Children and Their Development Study was January 2003 to March 2004; for Generation R, April 2002 to January 2006; for Infancia y Medio Ambiente, November 2003 to January 2008; for Rhea, February 2007 to February 2008; and for Project Viva, April 1999 to November 2002. Statistical analyses were conducted from January 2018 to April 2019.

MAIN OUTCOMES AND MEASURES

Residential air pollution concentrations (ie, nitrogen oxide and particulate matter [PM]) during the first trimester of pregnancy were estimated using land-use regression and satellite-derived aerosol optical depth models. Free thyroxine, thyrotropin, and thyroid peroxidase antibody levels were measured across gestation. Hypothyroxinemia was defined as free thyroxine below the fifth percentile of the cohort distribution with normal thyrotropin levels, following the American Thyroid Association guidelines.

RESULTS

Among 9931 participants, the mean (SD) age was 31.2 (4.8) years, 4853 (48.9%) had more than secondary educational levels, 5616 (56.6%) were nulliparous, 404 (4.2%) had hypothyroxinemia, and 506 (6.7%) tested positive for thyroid peroxidase antibodies. Concentrations of nitrogen dioxide and PM with an aerodynamic diameter of 2.5 μm or less (PM2.5) were lower and had less variation in women in the US cohort than those in European cohorts. No associations of nitrogen oxide with thyroid function were found. Higher exposures to PM2.5 were associated with higher odds of hypothyroxinemia in pregnant women (odds ratio per 5-μg/m3 change, 1.21; 95% CI, 1.00-1.47). Although exposure to PM with an aerodynamic diameter of 10 μm or less was not significantly associated with hypothyroxinemia, the coefficient was similar to that for the association of PM2.5 with hypothyroxinemia (odds ratio per 10-μg/m3 change, 1.18; 95% CI, 0.93-1.48). Absorbances of PM2.5 and PM with aerodynamic diameter from 2.5 to 10 μg and were not associated with hypothyroxinemia. There was substantial heterogeneity among cohorts with respect to thyroid peroxidase antibodies (P for heterogeneity, <.001), showing associations of nitrogen oxide and PM with thyroid autoimmunity only in the women in the Generation R Study.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that first-trimester exposures to PM2.5 were associated with mild thyroid dysfunction throughout pregnancy. The association of PM2.5 exposure with thyroid function during pregnancy is of global health importance because air pollution exposure is widespread and hypothyroxinemia may adversely influence the brain development of offspring.

Establishment of cumulative assessment groups of pesticides for their effects on the thyroid

Cumulative assessment groups of pesticides have been established for two specific effects on the thyroid: firstly hypothyroidism, and secondly parafollicular cell (C‐cell) hypertrophy, hyperplasia and neoplasia. Sources of uncertainties resulting from the methodological approach and from the limitations in available data and scientific knowledge have been identified and considered. This report supports the publication of a scientific report on cumulative risk assessment to pesticides affecting the thyroid, in which all uncertainties identified for either the exposure assessment or the establishment of the cumulative assessment groups are incorporated into a consolidated risk characterisation.

This publication is linked to the following EFSA Supporting Publications article: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2019.EN-1703/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2019.EN-1707/full

This publication is linked to the following EFSA Journal articles: http://onlinelibrary.wiley.com/doi/10.2903/j.efsa.2019.5763/full

Polymer films containing chemically anchored diazonium salts with long-term stability as colorimetric sensors

We have prepared polymeric films as easy-to-handle sensory materials for the colorimetric detection and quantification of phenol derivatives (phenols) in water. Phenols in water resources result from their presence in pesticides and fungicides, among other goods, and are harmful ecotoxins. Colorless polymeric films with pendant diazonium groups attached to the acrylic polymer structure were designed and prepared for use as sensory matrices to detect phenol-derived species in water. Upon dipping the sensory films into aqueous media, the material swells, and if phenols are present, they react with the diazonium groups of the polymer to render a highly colored azo group, giving rise to the recognition phenomenon. The color development can be visually followed for a qualitative determination of phenols. Additionally, quantitative analysis can be performed by two different techniques: a) by using a UV-vis spectrophotometer (limit of detection of 0.12 ppm for 2-phenylphenol) and/or b) by using a smartphone with subsequent RGB analysis (limit of detection of 30 ppb for 2-phenylphenol).

Cardiometabolic traits mediated the relationship from urinary polycyclic aromatic hydrocarbons metabolites to heart rate variability reduction: A community-based study

Polycyclic Aromatic Hydrocarbons (PAHs) exposure was related with metabolic syndrome (MetS) and heart rate variability (HRV) reduction, and HRV was also affected by cardiometabolic traits. However, the role of cardiometabolic traits in the associations from PAHs exposures to HRV was largely unknown. We conducted this study to investigate whether the relationship between PAHs exposure and HRV reduction was mediated by cardiometabolic traits. Levels of urinary polycyclic aromatic hydrocarbons metabolites (OH-PAHs), 10min-HRV, and metabolic traits were accurately measured for 2476 participants from Wuhan-Zhuhai (WHZH) cohort. Single mediator and multiple mediator models were used to evaluate the mediation effects of cadiometabolic traits. The concentrations of ΣOH-PAHs ranged from 4.20 to 8.63 mg/mmol Cr. When compared with the lowest tertile, ΣOH-PAHs in the highest tertile were significantly related with 20% (95% confidence interval [95%CI]:1%, 40%), 35% (95%CI: 14%, 56%), 22% (95%CI: 1%, 44%), and 38% (95%CI: 9%, 68%) decreases in very low frequency (VLF), low frequency (LF), high frequency (HF), and total power (TP) for participants with MetS, respectively. No statistically significant associations between ΣOH-PAHs and HRV indices were observed for participants without MetS. Similar results were found when we investigated the relationships between OH-PAHs and HRV indices by three groups of OH-PAHs (including total hydroxynaphthalene [ΣOHNa], total hydroxy fluorene [ΣOHFlu], and total hydroxyphenanthrene [ΣOHPh] metabolites). Further, mediation analysis suggested that cardiometabolic traits, including fasting glucose (GLU), high density lipoprotein (HDL), and blood pressure partially mediated the relationship from ΣOH-PAHs to HRV reduction. GLU was the strongest mediator, with mediation percentages of 15.70% for VLF, 14.70% for LF, 43.03% for HF, and 5.61% for TP. Our study found that the relationships between OH-PAHs and HRV reduction differed among participants with and without MetS, and these relationships were found to be partially mediated by cardiometabolic traits, especially fasting glucose. Further studies are encouraged to validate our findings and investigate potential mechanisms.

Effects of the environmental endocrine disrupting compound benzo[a]pyrene on thyroidal status of abu mullet (Liza abu) during short-term exposure

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The half-life of BaP is 3–4 days and then it metabolized in the liver.

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BaP concentration in the muscle of treated fish reached a maximum level after 4 days.

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Exposure of fish to BaP resulted in a decrease in T3 and T4 plasma levels up to day 4.

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Exposure of fish to BaP resulted in an increase in TSH plasma level up to day 4.

Benzo[a]Pyrene (BaP) is a ubiquitous polycyclic aromatic hydrocarbon (PAH) that has been shown to disrupt the metabolism of thyroid hormone. Then, the present investigation aimed to study the effects of BaP on thyroid function in Liza abu. Fish were injected with 2, 10 and 25 mg/kg-bw of BaP. Samples were taken from blood, thyroid and muscle tissues at days 1, 2, 4, 7, and 14. Blood was evaluated for changes in the plasma levels of TSH, T3 and T4. Also, BaP bioaccumulation in the fish muscle was measured. Thyroid tissues were processed for routine histology. BaP concentration in the muscle of treated fish reached a maximum level after 4 days. Exposure of fish to BaP resulted in a significant decrease in T3 and T4 plasma level and increase in TSH concentration up to day 4. Also some pathological alterations were observed in BaP-exposed fish such as hemorrhage and increased number of large follicles with squamous epithelium. In conclusion, according to the results of the present investigation, short term exposure to sublethal concentrations of BaP significantly affected thyroid function in fish. The results revealed BaP ability to alter thyroid function.

Obesity mediated the association of exposure to polycyclic aromatic hydrocarbon with risk of cardiovascular events

Exposure to polycyclic aromatic hydrocarbons (PAHs) could cause high blood pressure (BP) and increased risk for atherosclerotic cardiovascular disease (ASCVD). However, the mechanisms underlying the relationship between them were unclear. We investigated potential mediation effect of obesity on the association of exposure to PAHs with high BP and increased risk for ASCVD. In the repeated measures study, 106 community-dwelling residents in Wuhan, China finished the physical examination in the winter and summer seasons, eight urinary PAHs metabolites were measured. Associations of urinary PAHs with high BP and increased risk for ASCVD were assessed using either linear mixed effect models or generalized estimating equations models. Mediation analysis was performed to evaluate the mediating effect of obesity on the association of urinary PAHs metabolites with high BP or increased risk of ASCVD. We observed the positive association between urinary PAHs metabolites and BP or the odds ratios for high BP (all P<0.05). Additionally, each one-unit increase in ln-transformed urinary levels of 4-hydroxyphenanthrene or the total of PAH metabolites was associated with a 12.63% or 11.91% increase in the estimated 10-year ASCVD risk (both P<0.05). The waist-to-height ratio mediated 29.0% of the association of urinary 4-hydroxyphenanthrene with increased risk of ASCVD (P<0.05). The findings suggest that PAHs exposure may be associated with elevated BP and an increased risk of ASCVD. Obesity may partially mediate the association between PAHs exposure and higher BP or increased risk of ASCVD.

Prenatal Exposure to Endocrine Disruptors and Reprogramming of Adipogenesis: An Early-Life Risk Factor for Childhood Obesity

Obesity is a global health problem. It is characterized by excess adipose tissue that results from either increase in the number of adipocytes or increase in adipocytes size. Adipocyte differentiation is a highly regulated process that involves the activation of several transcription factors culminating in the removal of adipocytes from the cell cycle and induction of highly specific proteins. Several other factors, including hormones, genes, and epigenetics, are among the most important triggers of the differentiation process. Although the main contributing factors to obesity are high caloric intake, a sedentary lifestyle, and genetic predisposition, strong evidence supports a role for life exposure to environmental pollutants. Endocrine-disrupting chemicals are exogenous, both natural and man-made, chemicals that disrupt the body signaling processes, thus interfering with the endocrine system. Several studies have shown that prenatal exposure to endocrine disruptors modulates the mechanisms, by which multipotent mesenchymal stem cells differentiate into adipocytes. This review discusses adipocytes differentiation and highlights the possible mechanisms of prenatal exposure to endocrine disruptors in reprogramming of adipogenesis and induction of obesity later in life. Therefore, this review provides knowledge that reduction of early life exposure to these chemicals could open the door for new strategies in the prevention of obesity, especially during childhood.

Is there any association between urinary metabolites of polycyclic aromatic hydrocarbons and thyroid hormone levels in children and adolescents?

Considering the possible effects of polycyclic aromatic hydrocarbons (PAHs) on thyroid function, the current study aims to investigate the association of PAH urinary metabolites with the level of thyroid hormones in a sample of Iranian children and adolescents. This cross-sectional study was conducted from September 2015 to July 2016 in Isfahan, Iran. Participants were 150 students, aged 6-18 years, who were selected by multistage cluster random sampling from schools of Isfahan province. Blood and urine samples of participants were obtained for measurement of thyroid hormone levels (measured by immunoradiometric assay) and PAH urinary metabolites, including 1-hydroxynaphthalene, 2-hydroxynaphthalene, 9-hydroxyphenanthrene, and 1-hydroxypyrene. The association of serum thyroid-stimulating hormone (TSH) and PAH urinary metabolites was determined by correlation and regression analyses. Multivariate regression analysis revealed significant association between serum TSH and PAH urinary metabolites; this association remained significant after adjustment for gender and age. The corresponding figures were r = 0.85 for 1-naphthol, r = 0.86 for 2-naphthol, r = 0.87 for 1-hydroxypyrene, and r = 0.42 for 9-phenantrol, respectively, all p values < 0.001. The mean levels of 1-hydroxypyrene and 9-phenanthrol were higher in boys than those in girls (p < 0.05). The findings of this study indicated significant positive association between urinary PAH biomarkers and the TSH level in children and adolescents. It can be suggested that long-term exposure to PAHs might result in thyroid function impairment. The clinical implication of the current findings should be confirmed by future longitudinal studies.

Increased risk for hypothyroidism after anticholinesterase pesticide poisoning: a nationwide population-based study

PURPOSE

Previous animal studies have reported that acute anticholinesterase pesticide (organophosphate and carbamate) poisoning may affect thyroid hormones. However, there is no human study investigating the association between hypothyroidism and anticholinesterase pesticide poisoning, and therefore, we conducted a retrospective nationwide population-based cohort study to delineate this issue.

METHODS

We identified 10,372 anticholinesterase pesticide poisoning subjects and matched 31,116 non-anticholinesterase pesticide poisoning subjects between 2003 and 2012 from the Nationwide Poisoning Database and the Longitudinal Health Insurance Database 2000, respectively, in a 1:3 ratio by index date, age, and sex for this study. We compared the cumulative incidence of hypothyroidism between the two cohorts by following up until 2013. Independent predictors for hypothyroidism were also investigated.

RESULTS

In total, 75 (0.72%) anticholinesterase pesticide poisoning subjects and 184 (0.59%) non-anticholinesterase pesticide poisoning subjects were diagnosed with hypothyroidism during the follow-up. Cox proportional hazard regression analysis showed that anticholinesterase pesticide poisoning subjects had higher risk for hypothyroidism than did non-anticholinesterase pesticide poisoning subjects (adjusted hazard ratio: 1.47, 95% confidence interval: 1.11-1.95) after adjusting for age, sex, hypertension, malignancy, liver disease, renal disease, atrial fibrillation or flutter, thyroiditis, goiter, other endocrine disorders, and mental disorder. Stratified analysis showed that anticholinesterase pesticide poisoning subjects had higher risk for hypothyroidism than did non-anticholinesterase pesticide poisoning subjects in terms of the age subgroup of 40-64 years, female sex, past history of goiter, follow-up of <1 month, and anticholinesterase pesticide poisoning subjects without atropine treatment (incidence rate ratio [IRR]: 1.66, 95% confidence interval: 1.20-2.30). Female sex, malignancy, renal disease, thyroiditis, goiter, mental disorder, and anticholinesterase pesticide poisoning without atropine treatment were independent predictors for hypothyroidism.

CONCLUSIONS

Anticholinesterase pesticide poisoning is associated with increased risk for hypothyroidism. Early evaluation of thyroid function in anticholinesterase pesticide poisoning subjects is suggested, especially in subjects without atropine treatment, aged 40-64 years, female sex, and past history of goiter.

An evaluation of the endocrine disruptive potential of crude oil water accommodated fractions and crude oil contaminated surface water to freshwater organisms using in vitro and in vivo approaches

Knowledge regarding the potential impacts of crude oil on endocrine signaling in freshwater aquatic vertebrates is limited. The expression of selected genes as biomarkers for altered endocrine signaling was studied in African clawed frog, Xenopus laevis, tadpoles and juvenile Mozambique tilapia, Oreochromis mossambicus, exposed to weathered bunker and unweathered refinery crude oil water accommodated fractions (WAFs). In addition, the expression of the aforementioned genes was quantified in X. laevis tadpoles exposed to surface water collected from the proximity of an underground oil bunker. The (anti)estrogenicity and (anti)androgenicity of crude oil, crude oil WAFs, and surface water were furthermore evaluated using recombinant yeast. Thyroid hormone receptor beta expression was significantly down-regulated in X. laevis in response to both oil WAF types, whereas a further thyroid linked gene, type 2 deiodinase, was up-regulated in O. mossambicus exposed to a high concentration of bunker oil WAF. In addition, both WAFs altered the expression of the adipogenesis-linked peroxisome proliferator-activated receptor gamma in X. laevis. The crude oil and WAFs exhibited antiestrogenic and antiandrogenic activity in vitro. However, O. mossambicus androgen receptor 2 was the only gene, representing the reproductive system, significantly affected by WAF exposure. Estrogenicity, antiestrogenicity, and antiandrogenicity were detected in surface water samples; however, no significant changes were observed in the expression of any of the genes evaluated in X. laevis exposed to surface water. The responses varied among the 2 model organisms used, as well as among the 2 types of crude oil. Nonetheless, the data provide evidence that crude oil pollution may lead to adverse health effects in freshwater fish and amphibians as a result of altered endocrine signaling. Environ Toxicol Chem 2017;36:1330-1342. © 2016 SETAC.

Metabolism of methiocarb and carbaryl by rat and human livers and plasma, and effect on their PXR, CAR and PPARα activities

The oxidative, reductive, and hydrolytic metabolism of methiocarb and the hydrolytic metabolism of carbaryl by liver microsomes and plasma of rats or humans were examined. The effects of the metabolism of methiocarb and carbaryl on their nuclear receptor activities were also examined. When methiocarb was incubated with rat liver microsomes in the presence of NADPH, methiocarb sulfoxide, and a novel metabolite, methiocarb sulfone were detected. Methiocarb sulfoxide was oxidized to the sulfone by liver microsomes and reduced back to methiocarb by liver cytosol. Thus, the interconversion between methiocarb and the sulfoxide was found to be a new metabolic pathway for methiocarb by liver microsomes. The product of methiocarb hydrolysis, which is methylthio-3,5-xylenol (MX), was also oxidized to sulfoxide form by rat liver microsomes. The oxidations were catalyzed by human flavin-containing monooxygenase isoform (FMO1). CYP2C19, which is a human cytochrome P450 (CYP) isoform, catalyzed the sulfoxidations of methiocarb and MX, while CYP1A2 also exhibited oxidase activity toward MX. Methiocarb and carbaryl were not enzymatically hydrolyzed by the liver microsomes, but they were mainly hydrolyzed by plasma and albumin to MX and 1-naphthol, respectively. Both methiocarb and carbaryl exhibited PXR and PPARα agonistic activities; however, methiocarb sulfoxide and sulfone showed markedly reduced activities. In fact, when methiocarb was incubated with liver microsomes, the receptor activities were decreased. In contrast, MX and 1-naphthol showed nuclear receptor activities equivalent to those of their parent carbamates. Thus, the hydrolysis of methiocarb and carbaryl and the oxidation of methiocarb markedly modified their nuclear receptor activities.

Developmental neurotoxicity of succeeding generations of insecticides

Insecticides are by design toxic. They must be toxic to effectively kill target species of insects. Unfortunately, they also have off-target toxic effects that can harm other species, including humans. Developmental neurotoxicity is one of the most prominent off-target toxic risks of insecticides. Over the past seven decades several classes of insecticides have been developed, each with their own mechanisms of effect and toxic side effects. This review covers the developmental neurotoxicity of the succeeding generations of insecticides including organochlorines, organophosphates, pyrethroids, carbamates and neonicotinoids. The goal of new insecticide development is to more effectively kill target species with fewer toxic side effects on non-target species. From the experience with the developmental neurotoxicity caused by the generations of insecticides developed in the past advice is offered how to proceed with future insecticide development to decrease neurotoxic risk.

Association between polycyclic aromatic hydrocarbons and thyroid function among males and females: data from NHANES 2007-2008

The objective of this study was to evaluate the association between thyroid function and exposure to selected polycyclic aromatic hydrocarbons (PAH) among those aged ≥ 20 years. Thyroid variables considered for evaluation were thyroid-stimulating hormone, free and total serum thyroxine (FT4, TT4), free and total triiodothyronine (FT3, TT3), and thyroglobulin. PAH metabolites in urine for which data were analyzed were 1-hydroxynaphthalene, 2-hydroxynaphthalene, 2-hydroxyfluorene, 3-hydroxyfluorene, 9-hydroxyfluorene, 1-hydroxyphenanthrene, 2-hydroxyphenanthrene, 3-hydroxyphenanthrene, and 1-hydroxypyrene. Using data from 2007 to 2008 National Health and Nutrition Examination Survey, regression models with logs of thyroid variables as dependent variables and PAH exposure, age, race/ethnicity, iodine sufficiency, smoking status, and others as independent variables were fitted. For females, increased levels of 2-hydroxynapthalene, 2-hydroxyphenanthrene, and 1-hydroxypyrene were associated with elevated levels of TT3. For males, increased levels of 1-hydroxyphenanthrene, 2-hydroxyphenanthrene, and 9-hydroxypyrene were associated with decreased levels of FT4.

Exposure to non-persistent pesticides and thyroid function: A systematic review of epidemiological evidence

Numerous pesticides are recognized for their endocrine-disrupting properties. Non-persistent pesticides such as organophosphates, dithiocarbamates and pyrethroids may interfere with thyroid function as suggested by animal studies. However, the influence of chronic exposure to these compounds on thyroidal functions in humans remains to be determined. The present study aimed to review epidemiological evidence for an association between exposure to non-persistent pesticides and circulating levels of thyroid hormones (thyroxin [T4] and triiodothyronine [T3]) and thyroid-stimulating hormone (TSH). A systematic review was conducted using MEDLINE, SCOPUS and Virtual Health Library (BVS) databases. Articles were limited to original studies and reports published in English, Portuguese or Spanish. Nineteen epidemiological studies were identified, 17 of which were cross-sectional, 14 were of occupationally exposed workers and 11 used exposure biomarkers. Fungicides and organophosphates (OP) insecticides were the most studied pesticides. Although methodological heterogeneity between studies was noted, particularly regarding study design, exposure assessment, and control of confounding, most of them showed associations with changes in T3 and T4, and/or TSH levels, while results from a few of these are consistent with experimental data supporting the findings that non-persistent pesticide exposure exerts hypothyroid-like effects. However, reporting quality was moderate to poor in 50% of the studies, particularly regarding method of selection of participants and discussion of external validity. Overall, current knowledge regarding the impact of non-persistent pesticides on human thyroid function is still limited. Given the widespread use of pesticides, future research should assess effects of exposure to currently-used pesticides in cohort studies combining comprehensive questionnaire-based assessment and biomarkers. Investigators need to pay particular attention to exposure during critical windows of brain development and exposure in agricultural populations.

Urinary polycyclic aromatic hydrocarbons and measures of oxidative stress, inflammation and renal function in adolescents: NHANES 2003-2008

OBJECTIVE

Recent evidence has suggested that polycyclic aromatic hydrocarbons (PAHs) may contribute to cardiometabolic and kidney dysfunction by increasing oxidative stress, but little is known about impacts in childhood.

STUDY DESIGN

We performed cross-sectional analyses of 660 adolescents aged 12-19 years in the 2003-2008 National Health and Nutrition Examination Survey (NHANES), using levels of 10 monohydroxylated urinary PAH metabolites as our exposure. Our primary outcomes of interest were biomarkers of oxidative stress and renal function, including estimated glomerular filtration rate (eGFR), urinary albumin to creatinine ratio (ACR), insulin resistance, and serum uric acid, gamma glutamyl transferase (GGT) and C-reactive protein (CRP).

RESULTS

We observed statistically significant associations between PAH metabolites and levels of serum GGT, CRP, uric acid and eGFR. Each 100% increase in 2-hydroxyphenanthrene was related to a 3.36% increase in uric acid (95% CI: 0.338-6.372; p=0.032), a 3.86% increase in GGT (95% CI: 1.361-6.362; p=0.005) and a 16.78% increase in CRP (95% CI: 1.848-31.689; p=0.029). Each 100% increase in 4-hydroxyphenanthrene was associated with a 6.18% increase in GGT (95% CI: 4.064-8.301; p<0.001) and a 13.66% increase in CRP (95% CI: 2.764-24.564; p=0.017). Each 100% increase in 9-hydroxyfluorene was associated with a 2.58% increase in GGT (95% CI: 0.389-4776; p=0.024). Each 100% increase in 3-hydroxyphenanthrene was associated with a 2.66% decrease in eGFR (95% CI: -4.979 to -0.331; p=0.028).

CONCLUSIONS

Urinary PAH metabolites were associated with serum uric acid, GGT and CRP, suggesting possible impacts on cardiometabolic and kidney function in adolescents. Prospective work is needed to investigate the potential long-term health consequences of these findings.

Association of polycyclic aromatic hydrocarbons (PAHs) and lead co-exposure with child physical growth and development in an e-waste recycling town

Informal e-waste recycling activities results in serious environmental pollution of PAHs. We evaluated the body burden of 16 PAH congeners and potential health risks for children. A total of 167 children from exposed and reference area entered this study. Child blood samples were collected; height, weight, head and chest circumferences were measured. Blood PAH and lead concentrations were determined. The blood median of total PAHs from the exposed group was significantly higher than the reference group (68.53μg/L vs. 26.92μg/L, P<0.01). The major sources of Σ16-PAH and Σ7 carcinogenic-PAH were residence adjacent to e-waste workshop, paternal occupation related to e-waste recycling and house as a workshop. Inverse correlations were observed in the age and milk consumption with these two PAH groups, while a positive association was found between BMI and Σ7 carcinogenic-PAH, and between child height and blood lead. When divided into high and low exposure groups by Σ16-PAH, a significant negative association was found between body height and blood PAHs (β and 95%CI: -3.838, -6.469 to -1.206), while for weight and chest circumferences, negative associations were obtained only in the male subgroup before adjustment. After adjustment by sex, age, child milk products consumption per month and blood lead, child height was negatively associated with Σ16-PAH (β and 95%CI: -3.884, -6.736 to -1.033). Same trends were observed for child chest circumference (β and 95%CI: -1.147, -2.229 to -0.065). We suggest a negative association of PAHs and child height and chest circumference, while the correlation is more obvious in boys.

Evaluation of the ToxRTool's ability to rate the reliability of toxicological data for human health hazard assessments

Regulatory agencies often utilize results from peer reviewed publications for hazard assessments. A problem in doing so is the lack of well-accepted tools to objectively, efficiently and systematically assess the quality of published toxicological studies. Herein, we evaluated the publicly available software-based ToxRTool (Toxicological data Reliability assessment Tool) for use in human health hazard assessments. The ToxRTool was developed by the European Commission's Joint Research Center in 2009. It builds on Klimisch categories, a rating system established in 1997, by providing additional criteria and guidance for assessing the reliability of toxicological studies. It also transparently documents the study-selection process. Eight scientists used the ToxRTool to rate the same 20 journal articles on thyroid toxicants. Results were then compared using the Finn coefficient and "AC1" to determine inter-rater consistency. Ratings were most consistent for high-quality journal articles, but less consistent as study quality decreased. Primary reasons for inconsistencies were that some criteria were subjective and some were not clearly described. It was concluded, however, that the ToxRTool has potential and, with refinement, could provide a more objective approach for screening published toxicology studies for use in health risk evaluations, although the ToxRTool ratings are primarily based on study reporting quality.

Synergistic interaction between polycyclic aromatic hydrocarbons and environmental tobacco smoke on the risk of obesity in children and adolescents: The U.S. National Health and Nutrition Examination Survey 2003-2008

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) may be obesogens. However, the role of PAHs independent of environmental tobacco smoke (ETS) is unclear, and the interaction between PAHs and ETS remains unknown.

METHODS

We performed cross-sectional analyses of urinary concentrations of PAH metabolites, body mass index (BMI), and waist circumference (WC) in 1985 people aged 6-18 years using data from the 2003-2008 U.S. National Health and Nutrition Examination Survey. ETS exposure level was measured as serum cotinine level.

RESULTS

PAH metabolites were positively associated with BMI and WC in both the ETS-unexposed and ETS-exposed groups. The adjusted odds ratios for general obesity defined by age- and sex-specific BMI≥95th percentile across the quartiles of total PAH metabolites were 1, 4.51, 2.57, and 8.09 (Ptrend=0.003) in the ETS-unexposed group and 1, 2.02, 1.83, and 3.86 (Ptrend<0.001) in the ETS-exposed group. However, the association of PAH metabolites with obesity became stronger as serum cotinine levels increased (Pinteraction<0.05). Among those with high ETS exposure, the adjusted odds ratios for general obesity across quartiles of total PAH metabolites were 1, 2.89, 5.26, and 16.29 (Ptrend<0.001). Compared to the low PAH-exposure group without exposure to ETS, the high ETS- and high PAH-exposure group had 33.85- and 17.64-fold greater risks of general and central obesity, respectively.

CONCLUSION

Environmental exposure to PAHs may be associated with childhood obesity irrespective of ETS. In particular, simultaneous exposure to PAHs and ETS may substantially increase the risk of obesity.

Urinary polycyclic aromatic hydrocarbons and childhood obesity: NHANES (2001-2006)

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) are known carcinogens and suspected endocrine disruptors. Prenatal exposure to PAHs has been associated with obesity in early childhood.

OBJECTIVE

We examined the association of urinary PAH metabolites with adiposity outcomes [body mass index (BMI) z-score, waist circumference (WC), and rate of obesity] in children and adolescents.

METHODS

We performed whole-sample analyses of 3,189 individuals 6-19 years of age who participated in the 2001-2006 National Health and Nutrition Examination Survey. We performed multivariate linear and logistic regression to analyze the association of BMI z-score, WC, and obesity with concentrations of single urinary PAH compounds and the sum of PAHs. Furthermore, the analyses were stratified by developmental stage [i.e., children (6-11 years) and adolescents (12-19 years)].

RESULTS

BMI z-score, WC, and obesity were positively associated with the molecular mass sum of the PAHs and the total sum of naphthalene metabolites. Most associations increased monotonically with increasing quartiles of exposure among children 6-11 years of age, whereas dose-response trends were less consistent for adolescents (12-19 years of age). Neither total PAHs nor total naphthalene metabolites were associated with overweight in either age group, and there was little evidence of associations between the outcomes and individual PAHs.

CONCLUSIONS

Total urinary PAH metabolites and naphthalene metabolites were associated with higher BMI, WC, and obesity in children 6-11 years of age, with positive but less consistent associations among adolescents.

CITATION

Scinicariello F, Buser MC. 2014. Urinary polycyclic aromatic hydrocarbons and childhood obesity: NHANES (2001-2006). Environ Health Perspect 122:299-303; http://dx.doi.org/10.1289/ehp.1307234.

Specific time of exposure during tadpole development influences biological effects of the insecticide carbaryl in green frogs (Lithobates clamitans)

The orchestration of anuran metamorphosis is initiated and integrated by thyroid hormones, which change dynamically during larval development and which may represent a target of disruption by environmental contaminants. Studies have found that some anurans experience increased rates of development when exposed to the insecticide carbaryl later in larval development, suggesting that this insecticide could affect thyroid hormone-associated biological pathways. However, the time in development when tadpoles are sensitive to insecticide exposure has not been clearly defined nor has the mechanism been tested. In two separate studies, we exposed recently hatched green frog (Lithobates clamitans) tadpoles to a single, three day carbaryl exposure in the laboratory at either 2, 4, 8, or 16 weeks post-hatching. We examined the impact of carbaryl exposure on mRNA abundance patterns in the brains of frogs following metamorphosis months after a single three day exposure (experiment 1) and in tadpole tails three days after exposure (experiment 2) using cDNA microarrays and quantitative real time polymerase chain reaction (QPCR) analyses. For tadpoles reared through metamorphosis, we measured tadpole growth and development, as well as time to, mass at, and survival to metamorphosis. Although carbaryl did not significantly impact tadpole development, metamorphosis, or survival, clear exposure-related alterations in both tail and brain transcript levels were evident when tadpoles were exposed to carbaryl, particularly in tadpoles exposed at weeks 8 and 16 post-hatching, indicating both short-term and long-term alterations in mRNA expression. These results indicate that carbaryl can have long-lasting effects on brain development when exposure occurs at sensitive developmental stages, which may have implications for animal fitness and function later in the life cycle.

Biomonitoring of polycyclic aromatic hydrocarbons from coke oven emissions and reproductive toxicity in nonsmoking workers

The objective of the cross-sectional study was to assess whether exposure to polycyclic aromatic hydrocarbons (PAHs) from coke oven emissions contributed to alteration of semen quality and sperm DNA integrity in nonsmoking workers. Nonsmoking coke oven workers from a steel plant in Taiwan served as the exposure groups (topside-oven workers for the high exposure group and side-oven workers for the low exposure group), and administrators and security personnel in the plant served as the control. An exposure assessment was conducted to determine both particulate and gaseous phase of PAH levels and urinary 1-hydroxypyrene (1-OHP) levels. Semen quality was analyzed according to WHO guidelines. DNA fragmentation and bulky DNA adducts were measured to assess sperm DNA integrity. There was no significant difference in sperm concentrations, vitality, and DNA fragmentation between the exposed group and the control. The high exposure group experienced significantly lower percentages of normal morphology as compared with the control (p=0.0001). Bulky DNA adducts were detected in the exposed group that were significant higher than the control (p=0.04). Exposure to PAHs from coke-oven emissions could contribute to increased levels of bulky DNA adducts in sperm.