Intake of Phthalate-tainted Foods and Serum Thyroid Hormones in Taiwanese Children and Adolescents

Sex-specific interactive effect of melamine and DEHP on a marker of early kidney damage in Taiwanese adults: A national population-based study from the Taiwan Biobank

Taiwan had the high incidence of chronic kidney disease (CKD) worldwide. Our objective was to examine associations between daily exposure of phthalates and melamine, two common nephrotoxins, and kidney damage risk in a well-established nationwide cohort. Study subjects were from Taiwan Biobank (TWB) with existing data of questionnaire and biochemical examinations. Average daily intake (ADI) levels of melamine and seven parental phthalates, including DEHP (di-2-ethylhexylphthalate), DiBP (Dibutyl phthalate), DnBP (Di-n-butyl phthalate), BBzP (Butyl benzyl phthalate), DEP (Diethyl phthalate), and DMP (Dimethyl phthalate) were estimated using a creatinine excretion-based model from urine melamine and 10 phthalate metabolites. Urine microalbumin to creatinine ratio (ACR) was used to represent for the outcome of kidney damage. Two statistical strategies were used: First, a weighted quantile sum (WQS) regression model to select the most important exposure variables of ADI levels of phthalates and melamine associated with ACR; Second, to examine effects of those most important exposure variables on ACR in multivariable linear regression models. In total, 1153 eligible adults were left for analyses. Of them, 591 (51.3%) and 562 (48.7%) were men and women, respectively, with a median age of 49 years old. By WQS, a significant and positive association was found between ADI of melamine and phthalates and ACR (β = 0.14, p = 0.002). ADI levels of melamine had the highest weight (0.57), followed by DEHP (0.13). Next, examining the two most important exposures in association with ACR, we found that the higher the melamine and DEHP intakes, the higher the ACR levels were found. An interaction effect was also found between melamine and DEHP intakes on urine ACR (p = 0.015). This result was more prominent in men (p = 0.008) than in women (p = 0.651). Environmental co-exposure of melamine and DEHP can potentially affect ACR in the community-dwelling Taiwanese adult population.

Associations between endocrine disruptor contamination and thyroid hormone homeostasis in Belgian type 1 diabetic children

PURPOSE

Humans are daily exposed to many environmental pollutants, some of which being suspected to be thyroid disruptors. Some populations could be particularly susceptible to thyroid disruption, such like diabetics due to the well-known relation between the thyroid function and the control of carbohydrate homeostasis by pancreas. Therefore, the aim of this study was to investigate the associations between the exposure to several persistent and non-persistent chemicals and thyroid hormones levels in children with type 1 diabetes.

METHODS

Blood and urine sample were collected from 54 children diagnosed for type 1 diabetes mellitus. The concentrations of 7 phthalate metabolites, 4 parabens, 7 bisphenols, benzophenone 3 and triclosan were measured in urine, while 15 organochlorine pesticides, 4 polychlorinated biphenyls (PCBs) and 7 perfluoroalkyl substances were analyzed in serum samples. In the same time, the blood levels of free thyroxine (fT4), thyroid stimulating hormone (TSH) and glycated hemoglobin (Hb1Ac) were determined.

RESULTS

We highlighted positive associations between serum perfluorohexane sulfonate and urinary monoethylphthalate levels, and TSH level in blood. We also found that PCB 138 was positively associated to fT4 while urinary levels of bisphenol F were negatively correlated to this hormone. Finally, we observed positive associations between Hb1Ac levels and the contamination by PCB 153 and two urinary phthalate metabolites: mono-2-ethyl-5-hydroxyhexyl phthalate and mono-2-ethyl-5-oxoxyhexyl phthalate.

CONCLUSION

Our results showed that our small cohort of children with type 1 diabetes mellitus is potentially susceptible to thyroid disruptions by some pollutants. Moreover, for these children, both di-(2-ethylhexyl) phthalate metabolites would potentially hamper the glucose homeostasis. Nevertheless, additional studies are mandatory to further explore these findings.

Associations of phthalates with NAFLD and liver fibrosis: A nationally representative cross-sectional study from NHANES 2017 to 2018

OBJECTIVE

Although phthalates are common environmental pollutants, few studies have focused on the relationship of phthalates exposure with non-alcoholic fatty liver disease (NAFLD) or liver fibrosis, and especially, the alternative phthalates have been questioned in recent years about whether they are better choices. Thus, this study aimed to explore the associations of exposure to major phthalates or alternative phthalates with NAFLD and liver fibrosis.

METHODS

Data of 1450 adults from the National Health and Nutrition Examination Survey (NHANES) 2017-2018 were collected. The urinary metabolite concentrations of di-2-ethylhexyl phthalate (DEHP), diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP) were detected. Controlled attenuation parameter (CAP) and median liver stiffness measurement (LSM) were acquired for quantitative diagnosis of NAFLD and liver fibrosis by vibration-controlled transient elastography. Multivariate logistic regression analysis and linear regression analysis were performed to examine the associations between phthalates and NAFLD and liver fibrosis.

RESULTS

After adjustment of the potential factors, the prevalence of NAFLD was significantly elevated among those in the fourth quartile of mono-(2-ethyl-5-carboxypentyl) phthalate (OR, 95%CI = 2.719, 1.296, 5.700, P = 0.016), mono (2-ethyl-5-hydroxyhexyl) phthalate (OR, 95%CI = 2.073, 1.111, 3.867, P = 0.037). No significant association was found between the alternative phthalates and NAFLD. The similar result was gained by linear regression analysis that MECPP was still significantly associated with Ln CAP (Q4 vs. Q1: β, 95%CI = 0.067, 0.017, 0.118, P = 0.027). After adjustment for the same covariates, no significant association between phthalates and liver fibrosis was found in logistics regression analysis.

CONCLUSIONS

All in all, higher prevalence of NAFLD is correlated with DEHP but not DINP or DIDP in American adults. There is no significant relationship between phthalates and liver fibrosis defined as LSM ≥ 8 Kpa. Nevertheless, further research is needed to provide evidence of causality.

Mediation effects of thyroid function in the associations between phthalate exposure and lipid metabolism in adults

Phthalates are a group of industrial chemicals widely used in everyday products including cosmetics, food packaging and containers, plastics, and building materials. Previous studies have indicated that urinary phthalate metabolites are associated with metabolic effects including those on lipid metabolism, but the results are mixed. Furthermore, whether thyroid function mediates the association between phthalate exposure and lipid metabolism remains unclear. In the present study, we explored whether changes in thyroid function markers mediate the associations between phthalate exposure and lipid metabolism indicators in Taiwanese adults. The cross-sectional data were obtained from the Taiwan Environmental Survey for Toxicants conducted in 2013. Levels of 11 urinary phthalate metabolites, levels of 5 thyroid hormones, and 8 indicators of lipid metabolism were assessed in 222 Taiwanese adults. The relationships of urinary phthalate metabolite levels with serum thyroid hormone levels and lipid metabolism indicators were explored using multiple regression models. Mediation analysis was conducted to evaluate the role of thyroid function in the association between phthalate exposure and lipid metabolism. The metabolite of di(- 2-ethylhexyl) phthalate (∑DEHPm) exhibited a significant positive association with the lipid metabolite indicator of high-density lipoprotein cholesterol (HDL-C; β = 0.059, 95% confidence interval [CI] = 0.009, 0.109) in adults, and the thyroid function indicator thyroxine (T₄) had a significant negative association with the metabolite ∑DEHPm (β = - 0.059, 95% CI = - 0.101, - 0.016) and a significant negative association with HDL-C (β = - 0.284, 95% CI = - 0.440, - 0.128). The T₄ indirect effect was 0.015 (95% CI = - 0.0087, 0.05), and the mediation effect was 32.2%. Our results support the assumption that exposure to phthalates influences the homeostasis of lipid metabolism by interfering with thyroid function.

Plasticizers: negative impacts on the thyroid hormone system

This review aims to understand the impacts of plasticizers on the thyroid system of animals and humans. The thyroid gland is one of the earliest endocrine glands that appear during embryogenesis. The thyroid gland synthesizes thyroid hormones (TH), triiodothyronine (T3), and thyroxine (T4) that are important in the regulation of body homeostasis. TH plays critical roles in regulating different physiological functions, including metabolism, cell growth, circadian rhythm, and nervous system development. Alteration in thyroid function can lead to different medical problems. In recent years, thyroid-related medical problems have increased and this could be due to rising environmental pollutants. Plasticizers are one such group of a pollutant that impacts thyroid function. Plasticizers are man-made chemicals used in a wide range of products, such as children's toys, food packaging items, building materials, medical devices, cosmetics, and ink. The increased use of plasticizers has resulted in their detection in the environment, animals, and humans. Studies indicated that plasticizers could alter thyroid function in both animals and humans at different levels. Several studies demonstrated a positive and/or negative correlation between plasticizers and serum T4 and T3 levels. Plasticizers could also change the expression of various TH-related genes and proteins, including thyroid-stimulating hormone (TSH), thyrotropin-releasing hormone (TRH), and transporters. Histological analyses demonstrated thyroid follicular cell hypertrophy and hyperplasia in response to several plasticizers. In conclusion, plasticizers could disrupt TH homeostasis and the mechanisms of toxicity could be diverse.

Urinary levels of phthalate esters and heavy metals in adolescents with thyroid colloid cysts

We aimed to evaluate 14 urinary phthalate metabolites and 4 toxic metals in adolescents having thyroid colloid cyst (TCC) and compare with age and sex-matched others without TCC. Phthalate metabolites were analysed with UPLC-MS/MS and heavy metals with ICP-MS. TCC ratios in tertile subgroups of pollutants were compared with multiple logistic regression analysis after adjusting for age, sex, z-scores for body mass index and urinary creatinine values. Adolescents having the highest tertile of mono (2-ethylhexyl) phthalic acid and mercury had increased odds and those with the highest tertiles of monocarboxy-isononyl phthalate, mono (3-carboxypropyl) phthalate, monoisobutyl phthalate had lower odds for TCC than counterparts. The odds of TCC were lower for those in the second and the third tertiles. No differences in TCC ratios were detected with other pollutants. Given phthalate esters' and toxic metals' specific interactions on TCC, further studies were necessary to assess the influence of chemicals on TCC.

Longitudinal changes in oxidative stress and early renal injury in children exposed to DEHP and melamine in the 2011 Taiwan food scandal

In 2011, phthalates, mainly di-(2-ethylhexyl) phthalate (DEHP), were found to have been added to a variety of foods in Taiwan, increasing the risk of microalbuminuria in children. Exposure to melamine perhaps modifies that risk. This prospective cohort study investigates whether renal injury resulting from exposure to DEHP-tainted foods from the 2011 Taiwan Food Scandal is reversed over time. The temporal and interactive effects of past daily DEHP intake, current daily DEHP intake, and urinary melamine levels on oxidative stress and renal injury were also examined. Two hundred possibly DEHP-affected children (aged < 18 years) were enrolled in the first survey wave (August 2012-January 2013), with 170 and 159 children in the second (July 2014-February 2015) and third waves (May 2016-October 2016), respectively. The first wave comprised questionnaires that were used to collect information about possible past daily DEHP intake from DEHP-tainted foods. One-spot first morning urine samples were collected to measure melamine levels, phthalate metabolites, and markers indicating oxidative stress (malondialdehyde and 8-oxo-2'-deoxyguanosine), and renal injury (albumin/creatinine ratio (ACR) and N-acetyl-beta-D-glucosaminidase) in all three waves. Generalized estimating equation (GEE) modeling revealed that both past daily DEHP intake and time might affect urinary ACR. However, most interactions were negative and significant correlation was observed only during the second wave (P for interaction = 0.014) in the group with the highest past daily DEHP intake (>50 μg/kg/day). Urinary melamine levels were found to correlate significantly with both urinary ACR and oxidative stress markers. The highest impact associated with exposure to DEHP-tainted foods in increasing urinary ACR of children was observed during the first wave, and the effect may partially diminish over time. These results suggest that continuous monitoring of renal health and other long-term health consequences is required in individuals who were affected by the scandal in 2011.

Intrauterine exposure to di(2-ethylhexyl) phthalate (DEHP) disrupts the function of the hypothalamus-pituitary-thyroid axis of the F1 rats during adult life

INTRODUCTION

DEHP is an endocrine disruptor widely used in the production of malleable plastics. DEHP exposure was associated with altered hypothalamic-pituitary-thyroid (HPT) axis function. Although previous studies reported deleterious effects of DEHP exposure during the intrauterine period, few studies have evaluated the direct effects triggered by this endocrine disruptor on the offspring animals' thyroid function. This study aimed to investigate the impact of intrauterine exposure to DEHP on the HPT axis function programming of the offspring animals during adulthood.

METHODS

Pregnant Wistar rats were orally treated with corn oil or corn oil supplemented with DEHP (0.48 or 4.8 mg/kg/day) throughout the gestational period. The offspring rats were euthanized on the 90th postnatal day. Hypothalamus, pituitary, thyroid, and liver were collected to analyze gene expression and protein content through qPCR and Western Blot. Blood was collected to determine TSH and thyroid hormone levels through fluorometric or chemiluminescence immunoassays.

RESULTS

In the adult F1 female rats, the highest dose of DEHP decreased TSH serum levels. In the thyroid, DEHP reduced the gene expression and/or protein content of NIS, TSHR, TG, TPO, MCT8, NKX2.1, PAX8, and FOXE1. These data are consistent with the reduction in T4 serum levels of the F1 DEHP-exposed female rats. In the liver, DEHP exposure increased the mRNA expression of Dio1 and Ttr, while the highest dose of DEHP reduced the mRNA expression of Ugt1a1 and Ugt1a6. Conversely, in the F1 male adult rats, TSHB expression and TSH serum levels were increased in DEHP-exposed animals. In the thyroid, except for the reduced protein content of TSHR, none of the evaluated genes/proteins were altered by DEHP. TH serum levels were not changed in the DEHP-exposed F1 male rats compared to the control group. Additionally, there were no significant alterations in the expression of hepatic enzymes in these animals.

DISCUSSION/CONCLUSIONS

Our results demonstrated, for the first time, that intrauterine exposure to DEHP disrupts the HPT axis function in male and female offspring rats and strongly suggest that DEHP exposure increases the susceptibility of the offspring animals to develop thyroid dysfunctions during adulthood.

Urinary Concentrations of Major Phthalate and Alternative Plasticizer Metabolites in Children of Thailand, Indonesia, and Saudi Arabia, and Associated Risks

Phthalates are widely used in consumer products and are well-known for adverse endocrine outcomes. Di-(2-ethylhexyl) phthalate (DEHP), one of the most extensively used phthalates, has been rapidly substituted with alternative plasticizers in many consumer products. The aim of this study was to assess urinary phthalate and alternative plasticizer exposure and associated risks in children of three Asian countries with different geographical, climate, and cultural characteristics. Children were recruited from elementary schools of Saudi Arabia (n = 109), Thailand (n = 104), and Indonesia (n = 89) in 2017-2018, and their urine samples were collected. Metabolites of major phthalates and alternative plasticizers were measured in the urine samples by HPLC-MS/MS. Urinary metabolite levels differed substantially between the three countries. Metabolite levels of diisononyl phthalate (DiNP), diisodecyl phthalate (DiDP), di(2-ethylhexyl) terephthalate (DEHTP), and 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH) were the highest in Saudi children: Median urinary concentrations of oxo-MiNP, OH-MiDP, 5cx-MEPTP, and OH-MINCH were 8.3, 8.4, 128.0, and 2.9 ng/mL, respectively. Urinary DEHP metabolite concentrations were the highest in the Indonesian children. The hazard index (HI) derived for the plasticizers with antiandrogenicity based reference doses (RfD_AA) was >1 in 86%, 80%, and 49% of the Saudi, Indonesian, and Thai children, respectively. DEHP was identified as a common major risk driver for the children of all three countries, followed by DnBP and DiBP depending on the country. Among alternative plasticizers, urinary DEHTP metabolites were detected at levels comparable to those of DEHP metabolites or higher among the Saudi children, and about 4% of the Saudi children exceeded the health based human biomonitoring (HBM)-I value. Priority plasticizers that were identified among the children of three countries warrant refined exposure assessment for source identification and relevant exposure reduction measures.

Dietary Intake of Endocrine Disrupting Substances Presents in Environment and Their Impact on Thyroid Function

According to the available data, environmental pollution is a serious problem all over the world. Between 2015 and 2016, pollution was responsible for approximately nine million deaths worldwide. They also include endocrine disrupting chemicals (EDCs) that can interfere with the functioning of the thyroid gland. They are characterized by high persistence in the environment. These substances can enter the body through the gastrointestinal tract, respiratory system, as well as contact with the skin and overcome the placental barrier. EDC can be found in food, water, and personal care products. They can get into food from the environment and as a result of their migration to food products and cosmetics from packaging. EDCs can disrupt the functioning of the thyroid gland through a number of mechanisms, including disrupting the activation of thyroid receptors and the expression of genes that are related to the metabolism, synthesis, and transport of thyroid hormones (HT). There is a need to strengthen the food safety policy that aimed at the use of appropriate materials in direct contact with food. At the same time, an important action is to reduce the production of all waste and, when possible, use biodegradable packaging, which may contribute to the improvement of the quality of the entire ecosystem and the health of food, thus reducing the risk of developing thyroid diseases.

Environmental Pollution and Chronic Kidney Disease

Chronic kidney disease (CKD) is a global public health problem associated with high rates of morbidity and mortality due to end-stage renal disease and cardiovascular disease. Safe and effective medications to reverse or stabilize renal function in patients with CKD are lacking, and hence it is important to identify modifiable risk factors associated with worsening kidney function. Environmental pollutants, including metals, air pollutant, phthalate and melamine can potentially increase the risk of CKD or accelerate its progression. In this review, we discuss the epidemiological evidence for the association between environmental pollution and kidney disease, including heavy metals, air pollution and other environmental nephrotoxicants in the general population.

Characterization of phthalate exposure in relation to serum thyroid and growth hormones, and estimated daily intake levels in children exposed to phthalate-tainted products: A longitudinal cohort study

BACKGROUND

No information is available on the long-term effects on thyroid and growth hormones of children exposed to phthalate-tainted products, despite the infamous 2011 Taiwan phthalate episode. We investigated estimated daily intake levels and their long-term effects on serum thyroid and growth hormone levels in children.

METHODS

We recruited 166 children (2-18 years old) in three visits who provided specimens and filled out a questionnaire from the Risk Assessment of Phthalate Incident in Taiwan (RAPIT) project study from 2012 to 2016. Morning spot urine samples were analyzed for nine phthalate metabolites. Serum thyroid (triiodothyronine [T₃], thyroxine [T₄], and free T₄) and growth hormone (insulin-like growth factor-1 [IGF-1] and its binding protein 3 [IGF-BP3]) levels were measured. A generalized estimating equation model was used to evaluate associations between phthalate metabolite levels and children's thyroid and growth hormone levels.

RESULTS

The median metabolite levels of monomethyl phthalate (MMP), Σdibutyl phthalate (DBP), and Σdi-(2-ethylhexyl) phthalate (DEHP) at visits 1, 2, and 3 were 6.59, 10.5, and 21.0 ng/mL, 0.15, 0.24, and 0.20 nmol/mL, and 0.15, 0.17, and 0.12 nmol/mL, respectively. After adjusting for potential confounding factors, we found that levels of urinary MMP were negatively associated with T₃ (β = -0.013, p = 0.047), T₄ (β = -0.016, p = 0.006), free T₄ (β = -0.012, p = 0.002), and IGF-BP3 (β = -0.025, p = 0.003). Urinary mono-ethyl phthalate (MEP) was negatively associated with IGF-1 (β = -0.027, p = 0.029) and IGF-BP3 (β = -0.016, p = 0.018). In addition, serum free T₄ was positively associated with urinary mono-2-ethyl-5-hydroxy hexyl phthalate (MEHHP) (β = 0.016, p = 0.043), mono-2-ethyl-5-oxohexyl phthalate (MEOHP) (β = 0.015, p = 0.024), and ΣDEHPm (β = 0.019, p = 0.020).

CONCLUSIONS

Our findings support the hypothesis that specific phthalates disturb the hemostasis of thyroid and growth hormone levels in children exposed to phthalate-tainted products.

Urinary biomarkers of phthalates exposure and risks of thyroid cancer and benign nodule

Phthalates have been reported to affect the function and growth of thyroid. However, there is little data on the effect of phthalates on thyroid oncogenesis. Here we explored the associations between phthalates exposure and the risks of thyroid cancer and benign nodule. We sex-matched 144 thyroid cancer, 138 benign nodule patients and 144 healthy adults from Wuhan, China. Eight phthalate metabolites in spot urine samples were quantified using high-performance liquid chromatography and tandem mass spectrometry. The associations of creatinine-corrected urinary phthalate metabolites with the risks of thyroid cancer and benign nodule were assessed using multivariable logistic regression models. We found that urinary monomethyl phthalate (MMP), mono(2-ethyl-5hydroxyhexyl) phthalate (MEHHP) and mono(2-ethylhexyl) phthalate (MEHP) associated with increased risks of thyroid cancer and nodule, with adjusted odds ratios (ORs) ranging from 1.74 to 4.78 comparing the extreme tertiles, and urinary monobutyl phthalate (MBP) was associated with decreased risks of thyroid cancer and benign nodule (all P for trends < 0.05). Male-specific positive associations of urinary monoethyl phthalate (MEP) with thyroid cancer and nodule as well as urinary mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) with thyroid cancer were also observed. Our results suggest that exposure to certain phthalates may contribute to increased risks of thyroid cancer and benign nodule.

Fast degradation of phthalate acid esters by polyoxometalate nanocatalysts through adsorption, esterolysis and oxidation

A novel route was created to facilitate the degradation of diethyl phthalate (DEP) upon micellar polyoxometalate (POM) catalysts and H₂O₂. The best catalytic activity was obtained using [C₁₆H₃₃N(CH₃)₃]H₄PMo₁₀V₂O₄₀ (N-hexadecyl-N,N,N-trimethylammonium tetrahydrogen decamolybdo-divanadophosphate, abbreviated as (CTA)H₄PMoV) with 90.2% degradation efficiency within 30 min, while the chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiency were about 77.7% and 74.3% within 40 min. The highest efficiency was attributed to the concentration of DEP by amphiphilic POM catalyst, coupling with its strong Brønsted acidity and higher redox potential to catalyze esterolysis and oxidation of DEP. This allowed the phthalate acid esters (PAEs) with long carbon chains in super low concentration of 0.03 μM to be efficiently decomposed. The above synergistic effects explored DEP being degraded into ethanol, lactic acid and CO₂, which were non-toxic to the water surroundings. And the reaction activation energy (Ea) of 12.49 kJ/mol was obtained upon the degradation of DEP with (CTA)H₄PMoV followed first-order kinetics. Meanwhile, (CTA)H₄PMoV acted as a heterogeneous catalyst, which showed long duration and higher stability with only 3.7% loss amount during ten recycles.

Association Between Diethylhexyl Phthalate Exposure and Thyroid Function: A Meta-Analysis

BACKGROUND

Diethylhexyl phthalate (DEHP) is widely used in industrial products, particularly as plasticizers and softeners. Because it is used extensively, DEHP has been detected in humans worldwide. Although epidemiological studies suggest that DEHP can disrupt the function of the hypothalamic-pituitary-thyroid (HPT) axis, evidence on the association between DEHP exposure and thyroid function remains inconclusive. Therefore, a comprehensive meta-analysis was performed to investigate the association between DEHP exposure and the HPT axis in humans.

METHODS

A literature search of the MEDLINE, EMBASE, and Web of Science databases was conducted to search for studies in which the correlation coefficient values or regression coefficient values between three major DEHP metabolites (i.e., monoethylhexyl phthalate [MEHP], mono [2-ethyl-5-hydroxyhexyl] phthalate [MEHHP], and mono [2-ethyl-5-oxohexyl] phthalate) and thyrotropin, free thyroxine (T4), or total T4 were determined. The association between DEHPs and thyroid hormone levels were evaluated using Pearson's correlation coefficients.

RESULTS

Thirteen eligible articles were included. Urinary MEHP and MEHHP concentration was negatively correlated with total T4. Pooled correlation coefficients between MEHP/MEHHP and total T4 were -0.02 [confidence interval (CI) -0.05 to 0.00] and -0.03 [CI -0.05 to -0.01], respectively. Urinary mono (2-ethyl-5-oxohexyl) phthalate concentration was positively correlated with thyrotropin, and the pooled correlation coefficient was 0.02 [CI 0.00-0.04].

CONCLUSIONS

The findings of this meta-analysis suggest a significant association between the exposure of DEHP metabolites and the function of the HPT axis.

Dibutyl-phthalate exposure from mesalamine medications and serum thyroid hormones in men

BACKGROUND

Dibutyl phthalate (DBP) is an endocrine disruptor and used in some medication coatings, such as mesalamine for treatment inflammatory bowel disease (IBD).

OBJECTIVES

To determine whether high-DBP from some mesalamine medications alters thyroid function.

METHODS

Seventy men with IBD, without thyroid disease or any radiation history participated in a crossover-crossback prospective study and provided up to 6 serum samples (2:baseline, 2:crossover, 2:crossback). Men on non-DBP mesalamine (background exposure) at baseline crossed-over to DBP-mesalamine (high exposure) then crossed-back to non-DBP mesalamine (B₁HB₂-arm) and vice versa for men on DBP-mesalamine at baseline (H₁BH₂-arm). Serum concentrations of total triiodothyronine (T3), total thyroxine (T4), free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH) and thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb).

RESULTS

After crossover in B₁HB₂-arm (26 men, 134 samples), T3 decreased 10% (95% confidence interval (CI): 14%,-5%), T3/T4 ratio decreased 8% (CI: 12%,-3%), TPOAb, and TgAb concentrations decreased, 11% (-20%, -2%) and 15% (-23%, -5%), respectively; after crossback, they increased. When men in the H₁BH₂-arm (44 men, 193 samples) crossed-over, T3 decreased 7% (CI: -11%, -2%) and T3/T4 ratio decreased 6% (CI: -9%, -2%). After crossback, only TgAb increased and FT4 decreased.

CONCLUSIONS

High-DBP novel exposure or removal from chronic high-DBP exposure could alter elements of the thyroid system, and most probably alters the peripheral T4 conversion to T3 and thyroid autoimmunity, consistent with thyroid disruption. After exposure removal, these trends were mostly reversed.

Thyroid Function Disruptors: from nature to chemicals

The modern concept of thyroid disruptors includes man-made chemicals and bioactive compounds from food that interfere with any aspect of the hypothalamus-pituitary-thyroid axis, thyroid hormone biosynthesis and secretion, blood and transmembrane transport, metabolism and local action of thyroid hormones. This review highlights relevant disruptors that effect populations through their diet: directly from food itself (fish oil and polyunsaturated fatty acids, pepper, coffee, cinnamon and resveratrol/grapes), through vegetable cultivation (pesticides) and from containers for food storage and cooking (bisphenol A, phthalates and polybrominated diphenyl ethers). Due to the vital role of thyroid hormones during every stage of life, we review effects from the gestational period through to adulthood, including evidence from in vitro studies, rodent models, human trials and epidemiological studies.

Interaction of melamine and di-(2-ethylhexyl) phthalate exposure on markers of early renal damage in children: The 2011 Taiwan food scandal

Melamine and phthalate, mainly di-(2-ethylhexyl) phthalate (DEHP), are ubiquitously present in the general environment. We investigated whether urine melamine levels can modify the relationship between DEHP exposure and markers of early renal damage in children. A nationwide health survey for Children aged ≤12 years possibly exposed to phthalates were enrolled between August 2012 and January 2013. They were administered questionnaires to collect details regarding past DEHP exposure to phthalate-tainted foodstuffs. Urine samples were measured melamine levels, phthalate metabolites and biomarkers of renal damage, including urine microalbumin/creatinine ratio (ACR), N-acetyl-beta-d-glucosaminidase (NAG), and β2-microglobulin. The study included 224 children who had a median urine melamine level (μg/mmol creatinine) of 1.61 ranging 0.18-47.42. Positive correlations were found between urine melamine levels and urine ACR as well as urine NAG levels (both Spearman correlation coefficients r = 0.24, n = 224, p < .001). The higher the past DEHP exposure or urine melamine levels, the higher the prevalence of microalbuminuria. An interaction effect was also found between urine melamine levels and past DEHP exposure on urine ACR. Melamine levels may further modify the effect of past DEHP exposure on urine ACR in children.

Lipid and Creatinine Adjustment to Evaluate Health Effects of Environmental Exposures

PURPOSE OF REVIEW

Urine- and serum-based biomarkers are useful for assessing individuals' exposure to environmental factors. However, variations in urinary creatinine (a measure of dilution) or serum lipid levels, if not adequately corrected for, can directly impact biomarker concentrations and bias exposure-disease association measures.

RECENT FINDINGS

Recent methodological literature has considered the complex relationships between creatinine or serum lipid levels, exposure biomarkers, outcomes, and other potentially relevant factors using directed acyclic graphs and simulation studies. The optimal measures of urinary dilution and serum lipids have also been investigated. Existing evidence supports the use of covariate-adjusted standardization plus creatinine adjustment for urinary biomarkers and standardization plus serum lipid adjustment for lipophilic, serum-based biomarkers. It is unclear which urinary dilution measure is best, but all serum lipid measures performed similarly. Future research should assess methods for pooled biomarkers and for studying diseases and exposures that affect creatinine or serum lipids directly.

Urinary melamine excretion and increased markers of renal tubular injury in patients with calcium urolithiasis: A cross-sectional study

Environmental low-dose melamine exposure has been associated with urolithiasis risk in adults, but it is unclear if this exposure can cause early renal damage. This cross-sectional study investigated the association of this exposure and early renal damage in patients with calcium urolithiasis. We recruited patients diagnosed with upper urinary tract calcium urolithiasis from three hospitals in southwestern Taiwan between November 2010 and January 2015. All patients completed a structured questionnaire and provided one-spot urine samples for the measurement of melamine level and markers of early renal injury, including N-acetyl b-d-glucosaminidase (NAG), β2-microglobulin (β2-MG), and microalbumin. We used urinary melamine levels as an indicator of environmental melamine exposure. A total of 309 patients (mean age of 54.7 ± 12.8 years) were studied. Median urinary melamine level (μg/mmol Cr) was 1.26 (interquartile range 0.48-3.29). A significant and positive correlation was found between urinary melamine concentration and urinary NAG levels (Spearman correlation coefficient, r = 0.157, p = 0.006, n = 309). With urinary melamine levels categorized into quartiles, multivariate regression results showed the same relationship, particularly in those with first stone episode. In this group, patients with the highest quartile of urinary melamine concentration had a 3.95-fold risk (95% confidence interval = 1.43-10.94) of high NAG levels (dichotomized by median), compared to the lowest quartile after adjustment. No association was found between urinary melamine concentration and urinary microalbumin levels. In conclusion, urinary melamine is significantly associated with urinary marker of early renal tubular injury, NAG, in urolithiasis patients, especially ones with first stone episode.

Associations of phthalates exposure with attention deficits hyperactivity disorder: A case-control study among Chinese children

Researches on associations between phthalates exposure and child attention deficit hyperactivity disorder (ADHD) are inconsistent. This study aimed to evaluate the associations of urinary phthalates with ADHD, co-occurring oppositional defiant disorder (ODD), related symptoms and behavior problems among Chinese children. We enrolled 225 ADHD cases and 225 healthy controls aged 6-13 years old in Liuzhou, China. Each child provided repeated urine samples at 4 visits. Eight phthalate metabolites were measured by high-performance liquid chromatography and tandem mass spectrometry. Child ADHD symptoms and related behaviors were assessed using Swanson, Nolan, and Pelham Version IV scale and child behavior checklist. Higher urinary concentrations of mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-(2-ethyl)-hexyl phthalate (MEHP) were dose-dependently associated with ADHD [odds ratios (ORs) ranged from 2.35 to 3.04 for the highest vs. the lowest tertile] and co-occurring ODD (ORs ranged from 3.27 to 4.44 for the highest vs. the lowest tertile) in the multivariable logistic regression models (all p for trend ≤ 0.01), which were consistent with positive trends of increased scores of inattention domain, hyperactive domain and ODD symptoms (all p for trend ≤ 0.01). Besides, the monomethyl phthalate (MMP) concentration was associated with higher scores of inattention domain and ODD symptoms (both p < 0.05). Additionally, the MEHHP, MEOHP and MEHP concentrations were related to child attention problems, aggressive behaviors and externalizing behaviors (all p < 0.05). We also observed positive associations of the MEHP concentration with depressed behaviors and internalizing behaviors (all p < 0.05). Our results indicate that child exposure to phthalates may contribute to ADHD, ODD and externalizing and internalizing behavior problems.

Intellectual evaluation of children exposed to phthalate-tainted products after the 2011 Taiwan phthalate episode

INTRODUCTION

Phthalate exposure may reduce intellectual development in young children. In 2011, numerous Taiwanese children had been reported to have consumed phthalate-tainted products. We investigated the effects of phthalate exposure on the intellectual development of these children after the 2011 Taiwan di-2-ethylhexyl phthalate (DEHP) episode.

METHODS

We recruited 204 children, aged 3-12 y, from 3 hospitals in Taiwan between 2012 and 2013. First-morning urine samples were collected for analyzing 5 phthalate metabolites. We applied a Bayesian model to estimate the past DEHP exposure (_estDEHP_ADD) of each participant before the 2011 DEHP episode. Demographic information, consumption of phthalate-tainted products, and maternal education, of each participant were obtained using a questionnaire. We used the Wechsler intelligence evaluation tools for assessing the children's and maternal intelligence quotient.

RESULTS AND DISCUSSION

The median levels of mono-2-ethylhexyl phthalate, mono(2-ethyl-5-hydroxyhexyl) phthalate, mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-n-butyl phthalate, and mono-iso-butyl phthalate in the children were 9.97, 45.8, 32.2, 46.2, and 24.3μg/g creatinine, respectively. Using the aforementioned urinary phthalate metabolites, we found that the children's verbal comprehension index (N =98) was significantly negatively associated with urinary log₁₀ MEOHP (β, -11.92; SE, 5.33; 95%CI, -22.52~ -1.33; P=0.028) and log₁₀ ΣDBP metabolites (β, -10.95; SE, 4.93; 95%CI, -20.74~ -1.16; P=0.029) after adjustment for age, gender, maternal IQ and education, passive smoking, _estDEHP_ADD, active and passive smoking during pregnancy. Through a tolerable daily intake-based approach, we only found a significant negative association between past estimate DEHP_ADD and VIQ_≥3-<6 in preschool children whereas no correlation was observed between current DEHP exposure and IQ_≥3-<6 score with/ without estimate DEHP_ADD adjustment. It revealed that the effect of past high-DEHP exposure on verbal-related neurodevelopment of younger child are more sensitive.

CONCLUSION

Our results are consistent with the hypothesis that exposure to DEHP and DnBP affects intellectual development in preschool and school-aged children, particularly their language learning or expression ability.

A comparative study of anaerobic fixed film baffled reactor and up-flow anaerobic fixed film fixed bed reactor for biological removal of diethyl phthalate from wastewater: a performance, kinetic, biogas, and metabolic pathway study

BACKGROUND

Phthalic acid esters, including diethyl phthalate (DEP), which are considered as top-priority and hazardous pollutants, have received significant attention over the last decades. It is vital for industries to select the best treatment technology, especially when the DEP concentration in wastewater is high. Meanwhile, anaerobic biofilm-based reactors are considered as a promising option. Therefore, in the present study, for the biological removal of DEP from synthetic wastewater, two different anaerobic biofilm-based reactors, including anaerobic fixed film baffled reactor (AnFFBR) and up-flow anaerobic fixed film fixed bed reactor (UAnFFFBR), were compared from kinetic and performance standpoints. As in the previous studies, only the kinetic coefficients have been calculated and the relationship between kinetic coefficients and their interpretation has not been evaluated, the other aim of the present study was to fill this research gap.

RESULTS

In optimum conditions, 90.31 and 86.91% of COD as well as 91.11 and 88.72% of DEP removal were achieved for the AnFFBR and UAnFFFBR, respectively. According to kinetic coefficients (except biomass yield), the AnFFBR had better performance as it provided a more favorable condition for microbial growth. The Grau model was selected as the best mathematical model for designing and predicting the bioreactors' performance due to its high coefficients of determination (0.97 < R²). With regard to the insignificant variations of the calculated Grau kinetic coefficients (K_G) when the organic loading rate (with constant HRT) increased, it can be concluded that both of the bioreactors can tolerate high organic loading rate and their performance is not affected by the applied DEP concentrations.

CONCLUSIONS

Both the bioreactors were capable of treating low-to-high strength DEP wastewater; however, according to the experimental results and obtained kinetic coefficients, the AnFFBR indicated higher performance. Although the AnFFBR can be considered as a safer treatment option than the UAnFFFBR due to its lower DEP concentrations in sludge, the UAnFFFBR had lower VSS/TSS ratio and sludge yield, which could make it more practical for digestion. Finally, both the bioreactors showed considerable methane yield; however, compared to the UAnFFFBR, the AnFFBR had more potential for bioenergy production. Although both the selected bioreactors achieved nearly 90% of DEP removal, they can only be considered as pre-treatment methods according to the standard regulations and should be coupled with further technology.

Performance, kinetic, and biodegradation pathway evaluation of anaerobic fixed film fixed bed reactor in removing phthalic acid esters from wastewater

Emerging and hazardous environmental pollutants like phthalic acid esters (PAEs) are one of the recent concerns worldwide. PAEs are considered to have diverse endocrine disrupting effects on human health. Industrial wastewater has been reported as an important environment with high concentrations of PAEs. In the present study, four short-chain PAEs including diallyl phthalate (DAP), diethyl phthalate (DEP), dimethyl phthalate (DMP), and phthalic acid (PA) were selected as a substrate for anaerobic fixed film fixed bed reactor (AnFFFBR). The process performances of AnFFFBR, and also its kinetic behavior, were evaluated to find the best eco-friendly phthalate from the biodegradability point of view. According to the results and kinetic coefficients, removing and mineralizing of DMP occurred at a higher rate than other phthalates. In optimum conditions 92.5, 84.41, and 80.39% of DMP, COD, and TOC were removed. DAP was found as the most bio-refractory phthalate. The second-order (Grau) model was selected as the best model for describing phthalates removal.

Effects of Gender on the Association of Urinary Phthalate Metabolites with Thyroid Hormones in Children: A Prospective Cohort Study in Taiwan

Phthalates are considered endocrine disruptors. Our study assessed the gender-specific effects of phthalate exposure on thyroid function in children. In total, 189 Taiwanese children were enrolled in the study. One-spot urine and blood samples were collected for analyzing 12 phthalate metabolites in urine and thyroid hormones. The association between urinary phthalate metabolites and serum thyroid hormones was determined using a generalized linear model with a log link function; the children were categorized into groups for analysis according to the 33rd and 66th percentiles. The data were stratified according to gender and adjusted for a priori defined covariates. In girls, a positive association existed between urinary di-2-ethylhexyl phthalate (DEHP) metabolites (mono-(2-ethylhexyl) phthalate, mono-(2-ethyl-5-oxohexyl) phthalate, and mono-(2-ethyl-5-hydroxyhexyl) phthalate) and free thyroxine (T4). In boys, urinary dibutyl phthalate (DBP) metabolites (mono-i-butyl phthalate and mono-n-butyl phthalate) were positively associated with free triiodothyronine (T3). After categorizing each exposure into three groups, urinary DEHP metabolites were positively associated with free T3 levels in boys. Our results suggested that DEHP is associated with free T4 in girls and that DBP is associated with free T3 in boys. Higher DEHP metabolite concentrations exerted larger effects on free T3 in boys. These results reveal the gender-specific relationships between phthalate metabolites and thyroid hormones.