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

Hair-Derived Exposome Exploration of Cardiometabolic Health: Piloting a Bayesian Multitrait Variable Selection Approach

Cardiometabolic health is complex and characterized by an ensemble of correlated and/or co-occurring conditions including obesity, dyslipidemia, hypertension, and diabetes mellitus. It is affected by social, lifestyle, and environmental factors, which in-turn exhibit complex correlation patterns. To account for the complexity of (i) exposure profiles and (ii) health outcomes, we propose to use a multitrait Bayesian variable selection approach and identify a sparse set of exposures jointly explanatory of the complex cardiometabolic health status. Using data from a subset (N = 941 participants) of the nutrition, environment, and cardiovascular health (NESCAV) study, we evaluated the link between measurements of the cumulative exposure to (N = 33) pollutants derived from hair and cardiometabolic health as proxied by up to nine measured traits. Our multitrait analysis showed increased statistical power, compared to single-trait analyses, to detect subtle contributions of exposures to a set of clinical phenotypes, while providing parsimonious results with improved interpretability. We identified six exposures that were jointly explanatory of cardiometabolic health as modeled by six complementary traits, of which, we identified strong associations between hexachlorobenzene and trifluralin exposure and adverse cardiometabolic health, including traits of obesity, dyslipidemia, and hypertension. This supports the use of this type of approach for the joint modeling, in an exposome context, of correlated exposures in relation to complex and multifaceted outcomes.

Association between Environmental Exposure to Multiclass Organic Pollutants and Sex Steroid Hormone Levels in Women of Reproductive Age

Organic pollutant exposure may alter sex steroid hormone levels in both animals and humans, but studies on mixture effects have been lacking and mainly limited to persistent organic pollutants, with few hormones being investigated. Moreover, measurements from a single blood or urine sample may not be able to reflect long-term status. Using hair analysis, here, we evaluated the relationship between multiclass organic pollutants and sex steroid hormones in 196 healthy Chinese women aged 25-45 years. Associations with nine sex steroid hormones, including progesterone, androstenedione (AD), testosterone (T), estrone (E1), and 17β-estradiol (E2), and eight related hormone ratios were explored on 54 pollutants from polychlorinated biphenyl (PCB), pesticide, and bisphenol families using stability-based Lasso regression analysis. Our results showed that each hormone was associated with a mixture of at least 10 examined pollutants. In particular, hair E2 concentration was associated with 19 pollutants, including γ-hexachlorocyclohexane, propoxur, permethrin, fipronil, mecoprop, prochloraz, and carbendazim. There were also associations between pollutants and hormone ratios, with pentachlorophenol, dimethylthiophosphate, 3-phenoxybenzoic acid, and flusilazole being related to both E1/AD and E2/T ratios. Our results suggest that exposure to background levels of pesticides PCB180 and bisphenol S may affect sex steroid hormone homeostasis among women of reproductive age.

Association of exposure to polycyclic aromatic hydrocarbons with thyroid hormones in adolescents and adults, and the influence of the iodine status

Some studies of endocrine-disrupting polycyclic aromatic hydrocarbon (PAH) exposure and thyroid hormones (THs) are inconclusive. To assess the associations between PAHs and THs, and the influence of the iodine status on PAHs-THs, we employed 648 adolescents (12-19 years old) and 2691 adults from the National Health and Nutrition Examination Survey 2007-2008 and 2011-2012. PAH metabolites [1-hydroxynaphthalene (1-NAP), 2-NAP, 1-hydroxyphenanthrene (1-PHE), 2-PHE, 3-PHE, 2-hydroxyfluorene (2-FLU), 3-FLU, 9-FLU, and 1-hydroxypyrene (1-PYR)], THs [total and free thyroxine (TT4 and FT4), total and free triiodothyronine (TT3 and FT3), thyroid stimulating hormone (TSH), and thyroglobulin (Tg)], peripheral deiodinase activity (GD) and thyroid's secretory capacity (GT) were involved. Multiple linear regression and weighted quantile sum (WQS) regression models were used to assess PAH-TH associations and the interaction between PAHs and the iodine status. Stratification analyses were conducted based on sex, smoking and iodine status. For adolescents, in a multivariable-adjusted regression model (β; 95% CI), 1-PHE (4.08%; 1.01%, and 7.25%), 2-PHE (3.98%; 0.70%, and 7.25%) and 9-FLU (3.77%; 1.10%, 7.47%) were positively correlated with TT3; 3-PHE and 1-PYR interacted with the iodine status (P-int < 0.05); 9-FLU was positively correlated with GD in both sexes. Combined exposure to PAHs was positively associated with Tg (0.137; 0.030, and 0.243), and negatively correlated with TSH (-0.087; -0.166, and -0.008). For adults, 2-NAP was positively correlated with FT3 (0.90%; 0.20%, and 1.61%), FT4 (1.82%; 0.70%, and 2.94%), TT3 (1.31%; 0.10%, and 2.63%), TT4 (2.12%; 0.90%, and 3.36%) and GT (2.22%; 1.01%, and 3.46%), but negatively correlated with TSH (-4.97%; -8.33%, and -1.49%); 1-NAP interacted with the iodine status (P-int < 0.05); 1-PHE was inversely correlated with TT3 in males; 2-PHE was positively correlated with TT3 in females. Combined exposure to PAHs was positively associated with FT3 (0.008; 0.001, and 0.014). Combined exposure to PAHs was positively associated with FT3, TT3 and GD, and negatively correlated with FT4, TT4 and GT in non-smoking adults; but positively associated with Tg (β = 0.140; 95% CI: 0.042, 0.237) in smoking adults. Our results indicated that combined and individual PAH exposure might be related to THs, and the iodine status had an influence on PAH-TH associations. These associations were not identical between adolescents and adults, and there were sex and smoking status differences.

Association of polycyclic aromatic hydrocarbon internal exposure and urinary iodine concentration with thyroid volume in children

Thyroid volume was proposed as a factor for malignancy in evaluating thyroid nodules. Previous studies have demonstrated the endocrine disrupting effect of polycyclic aromatic hydrocarbons (PAHs), but studies on the association between internal exposure of PAHs and thyroid volume are still scarce. In this work, we evaluated the association of polycyclic aromatic hydrocarbon internal exposure and urinary iodine concentration with thyroid volume in 590 school-age children without thyroid disease in Guangzhou, China. Urinary hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs), urinary iodine concentrations, and thyroid volumes were measured. The mean concentrations of urinary iodine and ΣOH-PAHs were 271.1 μg/L and 3.27 μg/L, respectively, and the mean thyroid volume was 2.4 mL. The associations of urinary iodine and OH-PAH concentrations with thyroid volume were investigated by multivariable linear regression and the Bayesian kernel machine regression models. Urinary ΣOH-PAHs were observed to be significantly positively associated with thyroid volume in multivariable linear regression models. The increase in each unit in the log-transformed concentration of ΣOH-PAHs caused 3.88% change in thyroid volume. The Bayesian kernel machine regression model demonstrated a positive joint effect of increased urinary ΣOH-PAHs on thyroid volume. Moreover, urinary ΣOH-PAHs were statistically significant linked to urinary iodine, and iodine mediated the relationship between urinary OH-PAHs and thyroid volume with the mediated proportions of 15.2.