Associations between pyrethroid exposure and serum sex steroid hormones in adults: Findings from a nationally representative sample

Associations between co-exposure to per- and polyfluoroalkyl substances and metabolic diseases: The mediating roles of inflammation and oxidative stress

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) pose potential risks to human health. In real-world settings, humans are exposed to various PFAS through numerous pathways.

OBJECTIVES

This study evaluated the associations between co-exposure to PFAS and obesity and its comorbidities, along with the mediating roles of inflammation and oxidative stress.

METHODS

We analyzed 11,090 participants from National Health and Nutrition Examination Survey (NHANES), 2003-2018. Linear regression, logistic regression, and generalized additive models were used to assess the individual effects of PFAS exposure on obesity and its comorbidities. The environmental risk score (ERS) was calculated using the adaptive elastic-net model to assess the co-exposure effects. Linear and logistic regression models explored the associations between ERS and obesity and its comorbidities. Mediation analyses explored the roles of inflammatory (neutrophils, lymphocytes, and alkaline phosphatase) and oxidative stress (gamma-glutamyl transferase, total bilirubin, and uric acid) markers in the associations between ERS and obesity and its comorbidities.

RESULTS

For each unit increase in ERS, the odds of obesity and type 2 diabetes mellitus (T2DM) increased 3.60-fold (95 % CI: 2.03, 6.38) and 1.91-fold (95 % CI: 1.28, 2.86), respectively. For each unit increase in ERS, BMI increased by 2.36 (95 % CI: 1.24, 3.48) kg/m2, waist circumference increased by 6.47 (95 % CI: 3.56, 9.37) cm, and waist-to-height ratio increased by 0.04 (95 % CI: 0.02, 0.06). Lymphocytes, alkaline phosphatase, and total bilirubin were significantly associated with both ERS and obesity, with mediation proportions of 4.17 %, 3.62 %, and 7.37 %, respectively. Lymphocytes, alkaline phosphatase, total bilirubin, and uric acid were significantly associated with both ERS and T2DM, with the mediation proportions of 8.90 %, 8.74 %, 29.73 %, and 38.19 %, respectively.

CONCLUSIONS

Co-exposure to PFAS was associated with obesity and T2DM, and these associations may be mediated by inflammation and oxidative stress. Further mechanistic and prospective studies are required to verify these associations.

Pyrethroids and reproductive function: some endocrine disrupting perspectives from molecular simulations

Pyrethroids are widely used insecticides with huge applications for household as well as agricultural purposes and contribute to improved product quality and higher yields. In recent decades, the demand for pyrethroids has increased significantly due to advantages such as broad-spectrum efficacy, high insecticidal potential, and lower pest resistance. However, several studies have suggested that human exposure to pyrethroids leads to reproductive problems. Sex hormone-binding globulin (SHBG) is an important hormone transport protein regulating the availability of steroids at their target site. The aim of our study was to investigate the structural interactions of commonly used pyrethroids, cypermethrin and deltamethrin, with ligand binding pocket of SHBG. Cypermethrin and deltamethrin were docked into the steroid binding pocket of SHBG using Schrodinger's induced fit docking (IFD) followed by molecular dynamics (MD) simulation studies. The resultant SHBG-pyrethroid complexes from IFD experiments were subjected to structural analysis including the molecular interactions followed by binding energy estimation. The analysis revealed that both the ligands were tightly bound in the SHBG pocket with high percentage of commonality among the SHBG residues between the indicated pyrethroid ligands and the SHBG native ligand, dihydrotestosterone (DHT). The estimated binding energy values for cypermethrin were less but close to the values calculated for the SHBG native ligand, DHT. However, the estimated binding energy values for deltamethrin were higher compared to the values calculated for SHBG native ligand, DHT. Furthermore, the MD simulation results also revealed the higher stability of SHBG-deltamethrin than SHBG-cypermethrin complex. To sum up, the results suggested that deltamethrin has a greater capability than cypermethrin to prevent sex steroid hormone from binding to SHBG, even though both pyrethroids have this ability. Consequently, this might hamper the circulatory transport of sex steroid hormones and their availability at the target site, subsequently interfering with reproductive function.

A multi-omics approach reveals that lotus root polysaccharide iron ameliorates iron deficiency-induced testicular damage by activating PPARγ to promote steroid hormone synthesis

Iron deficiency is a common nutritional issue that seriously affects male reproductive health. Lotus root polysaccharide iron (LRPF), a novel nutritional supplement, may ameliorate the damage caused by iron deficiency, however, the mechanism is unclear. In this study, we comprehensively determined the benefits of LRPF on reproduction in iron-deficient mice by integrating transcriptomics, microbiomics and serum metabolomics. Microbiomics showed that LRPF could restore changes to the intestinal microbiota caused by iron deficiency. Metabolomics results showed that LRPF stabilised steroid hormone and fatty acid metabolism in iron-deficient mice, reduced the content of ethyl chrysanthemumate (EC) and ameliorated the reproductive impairment. The transcriptomic analysis showed that LRPF regulated steroid hormone synthesis and the peroxisome proliferator-activated receptor (PPAR) signalling pathway in iron-deficient mice. In vitro experiments showed that LRPF could promote steroid hormone synthesis in Leydig cells by activating PPARγ. In conclusion, this study highlights the advantage of LRPF to improve testicular development.

Associations between DEET, Organophosphorus Insecticides, and Handgrip Strength in Diabetes: An NHANES Analysis

INTRODUCTION

Sarcopenia and diabetes mellitus (DM) have been shown to be related. It has been demonstrated that pesticides/insecticides are linked to various health issues, including DM. This study investigated the relationships between exposure to pesticides/insecticides and muscle strength among community-dwelling DM patients in a national sample of the United States (US).

METHODS

Data from the 2011-2012 and 2013-2014 U.S. National Health and Nutrition Examination Survey (NHANES) on people aged 20 years with diabetes were retrieved. A digital dynamometer was used to quantify handgrip strength, and urine pesticide concentrations were determined through laboratory testing. Regression models were used to investigate the relationship between pesticide/insecticide exposure and handgrip strength.

RESULTS

After weighting, the data from 412 NHANES participants represented 6,696,865 U.S. inhabitants. The mean age of the participants was 58.8 years. High para-nitrophenol levels (tertile 3 vs. tertile 1) were shown to be associated with lower handgrip strength in both males (aBeta = -7.25, 95% CI: -11.25, -3.25) and females (aBeta = -3.73, 95% CI: -6.89, -0.56). Further, females with elevated 2-isopropyl-4-methyl-pyrimidinol had decreased handgrip strength. Desethyl hydroxy N, N-diethyl-m-toluamide (DEET) was inversely related to handgrip strength in men aged ≥60 years. DEET acid and para-nitrophenol were inversely correlated to handgrip strength in women over 60 years.

CONCLUSIONS

This study has linked certain pesticides/insecticides to decreased muscle strength in people with diabetes. Para-nitrophenol, in particular, is negatively related to muscular strength in both males and females, and 2-isopropyl-4-methyl-pyrimidinol is inversely related to muscle strength in females.

Associations of pyrethroid exposure with bone mineral density and osteopenia in adults

INTRODUCTION

This study was to investigate the correlations between pyrethroid exposure and bone mineral density (BMD) and osteopenia.

MATERIALS AND METHODS

This cross-sectional study included 1389 participants over 50 years of age drawn from the 2007-2010 and 2013-2014 National Health and Nutrition Examination Survey (NHANES). Three pyrethroid metabolites, 3-phenoxybenzoic acid (3-PBA), trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropane-1-carboxylic acid (trans-DCCA), and 4-fluoro-3-phenoxybenzoic acid (4-F-3PBA) were used as indicators of pyrethroid exposure. Low BMD was defined as T-score < - 1.0, including osteopenia. Weighted multivariable linear regression analysis or logistic regression analysis was utilized to evaluate the correlation between pyrethroid exposure and BMD and low BMD. Bayesian kernel machine regression (BKMR) model was utilized to analyze the correlation between pyrethroids mixed exposure and low BMD.

RESULTS

There were 648 (48.41%) patients with low BMD. In individual pyrethroid metabolite analysis, both tertile 2 and tertile 3 of trans-DCCA were negatively related to total femur, femur neck, and total spine BMD [coefficient (β) = - 0.041 to - 0.028; all P < 0.05]. Both tertile 2 and tertile 3 of 4-F-3PBA were negatively related to total femur BMD (P < 0.05). Only tertile 2 [odds ratio (OR) = 1.63; 95% CI = 1.07, 2.48] and tertile 3 (OR = 1.65; 95% CI = 1.10, 2.50) of trans-DCCA was correlated with an increased risk of low BMD. The BKMR analysis indicated that there was a positive tendency between mixed pyrethroids exposure and low BMD.

CONCLUSION

In conclusion, pyrethroids exposure was negatively correlated with BMD levels, and the associations of pyrethroids with BMD and low BMD varied by specific pyrethroids, pyrethroid concentrations, and bone sites.

Pesticides exposure and compromised fitness in wild birds: Focusing on the reproductive endocrine disruption

Exposure of pesticides to wildlife species, especially on the aspect of endocrine disruption is of great concern. Wildlife species are more at risk to harmful exposures to the pesticides in their natural habitat through diet and several other means. Species at a higher tropic level in the food chain are more susceptible to the deleterious effects due to sequential biomagnifications of the pesticides/metabolites. Pesticides directly affect fitness of the species in the wild causing reproductive endocrine disruption impairing the hormones of the gonads and thyroid glands as reproduction is under the influence of cross regulations of these hormones. This review presents a comprehensive compilation of important literatures on the impact of the current use pesticides in disruption of both the hypothalamic-pituitary-gonadal and hypothalamic-pituitary-thyroid axes particularly in birds addressing impacts on the reproductive impairments and overall fitness. In addition to the epidemiological studies, laboratory investigations those provide supportive evidences of the probable mechanisms of disruption in the wild also have been incorporated in this review. To accurately predict the endocrine-disruption of the pesticides as well as to delineate the risk associated with potential cumulative effects, studies are to be more focused on the environmentally realistic exposure dose, mixture pesticide exposures and transgenerational effects. In addition, strategic screening/appropriate methodologies have to be developed to reveal the endocrine disruption potential of the contemporary use pesticides. Demand for adequate quantitative structure-activity relationships and insilico molecular docking studies for timely validation have been highlighted.

Effect of zinc intake on association between fluoride exposure and abnormal sex steroid hormones among US pubertal males: NHANES, 2013-2016

Excessive fluoride exposure can disturb the balance of sex hormones. Zinc is essential for sex hormone synthesis and spermatogenesis. But it is not clear how zinc affects the relationship of fluoride exposure with abnormal sex steroid hormones. Here, a total of 1008 pubertal males from the National Health and Nutrition Examination Survey (NHANES) in two cycles (2013-2014, 2015-2016) were enrolled. The concentrations of water fluoride and plasma fluoride and the levels of serum testosterone, estradiol, and sex hormone binding globulin (SHBG) were measured. Two 24-h dietary recall interviews were conducted to assess the dietary zinc intake. The relationships of fluoride exposure and zinc intake with sex hormones were examined using linear regression and logistic regression models, while the generalized additive model was used to evaluate their non-linear relationship. Our findings revealed that for every two-fold increase in plasma fluoride concentration, testosterone levels decreased by 7.27% (95% CI - 11.49%, - 2.86%) and estradiol levels decreased by 8.73% (95% CI - 13.61%, - 3.57%). There was also significant non-linear association observed between zinc intake and SHBG levels. Being in the first tertile of plasma fluoride had a 60% lower risk of high SHBG (OR = 0.40, 95% CI 0.18, 0.89) compared with being in the second tertile. When compared to the first tertile, being in the second tertile of zinc intake was associated with a 63% (OR = 0.37, 95% CI 0.14, 0.98) lower risk of high SHBG. Furthermore, we observed an interactive effect between the plasma fluoride and zinc intake on estradiol and SHBG, as well as the risk of high SHBG (P-interaction < 0.10). These findings suggest that fluoride exposure and zinc intake can affect sex steroid hormone levels and the risk of high SHBG. Notably, zinc intake may alleviate the increased risk of high SHBG and the abnormal changes of estradiol and SHBG caused by higher fluoride exposure.

Priority list of potential endocrine-disrupting chemicals in food chemical contaminants: a docking study and in vitro/epidemiological evidence integration

Diet is an important exposure route of endocrine-disrupting chemicals (EDCs), but many unfiltered potential EDCs remain in food. The in silico prediction of EDCs is a popular method for preliminary screening. Potential EDCs in food were screened using Endocrine Disruptome, an open-source platform for inverse docking, to predict the binding probabilities of 587 food chemical contaminants with 18 human nuclear hormone receptor (NHR) conformations. In total, 25 contaminants were bound to multiple NHRs such as oestrogen receptor α/β and androgen receptor. These 25 compounds mainly include pesticides and per- and polyfluoroalkyl substances (PFASs). The prediction results were validated with the in vitro data. The structural features and the crucial amino acid residues of the four NHRs were also validated based on previous literature. The findings indicate that the screening has good prediction efficiency. In addition, the epidemic evidence about endocrine interference of PFASs in food on children was further validated through this screening. This study provides preliminary screening results for EDCs in food and a priority list for in vitro and in vivo research.

Exploring the binding mechanism and adverse toxic effects of degradation metabolites of pyrethroid insecticides to human serum albumin: Multi-spectroscopy, calorimetric and molecular docking approaches

Pyrethroid insecticides (PIs), a class of structurally similar non-persistent organic pollutants, can be degraded and metabolized to more toxic, and longer half-life products. In this study, the binding interaction mechanisms between human serum albumin (HSA) and the main degradation metabolites of PIs, 3-phenoxybenzoic acid (3-PBA) and 4-fluoro-3-phenoxybenzoic acid (4-F-3-PBA), were studied by theoretical simulation and experimental verification. Steady state fluorescence spectra showed that the fluorescence quenching mechanism was static. According to the binding constant, 4-F-3-PBA (1.53 × 105 L mol-1) was bound more strongly to HSA than 3-PBA (1.42 × 105 L mol-1) in subdomain ⅡA (site I). It was found by isothermal titration calorimetry that the metabolites and HSA spontaneously combined mainly through hydrogen bond and van der Waals interaction. Ultraviolet absorption spectra and circular dichroism spectra showed that the metabolites caused slight changes in the microenvironment and conformation of HSA. The above results were proved by molecular docking. The toxicity properties of the metabolites were further analyzed by software, and 4-F-3-PBA was found to be more toxic than 3-PBA. Considering the high exposure level of these metabolites in food, the environment and human body, it is necessary to further explore the toxicity of PIs metabolites.

Association between pyrethroid exposure and osteoarthritis: a national population-based cross-sectional study in the US

BACKGROUND

With the restriction of organophosphorus and other insecticides, pyrethroids are currently the second most-used group of insecticides worldwide due to their advantages such as effectiveness and low toxicity for mammalian. Animal studies and clinical case reports have documented associations between adverse health outcomesand exposure to pyrethroids. At present, the association between chronic pyrethroid exposure and osteoarthritis (OA) remains elusive.

METHODS

Cross-sectional data from the National Health and Nutrition Examination Survey 1999-2002 and 2007-2014 were used to explore the associations of pyrethroid exposure and OA. Urinary level of 3-phenoxybenzoic acid (3-PBA) in urine samples was used to evaluate the exposure of pyrethroid, and OA was determined on the basis of self-reported physician diagnoses. Multivariable logistic regression models were used to investigate the association between pyrethroid exposure and OA.

RESULTS

Among the 6528 participants, 650 had OA. The weighted geometric mean of urinary volume-based 3-PBA concentration were 0.45 µg/L. With adjustments for major confounders, compared to participants in the lowest quartile of urinary volume-based 3-PBA, those in the highest quartilehad higher odds of OA (odds ratio, 1.39; 95% confidence interval: 1.01, 1.92). There was no nonlinear relationship between urinary volume-based 3-PBA and OA (P for non-linearity = 0.89).

CONCLUSION

High urinary 3-PBA concentration was associated with increased OA odds in the US adults. Pyrethroid exposure in the population should be monitored regularly.

Independent and Combined Associations of Blood Manganese, Cadmium and Lead Exposures with the Systemic Immune-Inflammation Index in Adults

Manganese (Mn), cadmium (Cd) and lead (Pb) have toxic effects on the immune system. However, their independent and combined effects on immune-inflammation responses are unclear. In recent years, the systemic immune-inflammation index (SII) has been developed as an integrated and novel inflammatory indicator. A retrospective cross-sectional study of 2174 adults ≥20 years old from the National Health and Nutrition Examination Survey (NHANES) 2015-2016 was conducted. Generalized linear models were used to evaluate the independent and combined associations of SII with blood Mn, Cd and Pb levels. As continuous variables, both blood Cd and Mn showed dose-dependent relationships with the SII before and after adjusting for all potential confounding factors. Metal concentrations were then converted into categorical variables. Compared with the adults in the lowest Cd or Mn tertile, those in the highest tertile had higher risks of elevated SII. Furthermore, co-exposure to Mn and Cd also showed a positive relationship with the SII after adjusting for all confounding factors. However, the single effect of Pb exposure and the joint effect of Pb and other metal exposures on the SII were not observed. This study provides important epidemiological evidence of the associations of SII with single and co-exposure effects of blood Mn, Cd, and Pb.

Association of urinary heavy metals co-exposure and adult depression: Modification of physical activity

OBJECTIVE

This study aimed to evaluate the association between urinary heavy metal mixture exposure and depression, and the modifying role of physical activity in the effects of heavy metal mixture on depression risk was also considered.

METHODS

Data of this study were derived from the National Health and Nutrition Examination Survey 2011-2016. Depression was measured by the Patient Health Questionnaire. We first selected 6 (cadmium, cobalt, tin, antimony, thallium, and mercury) from 14 heavy metals through elastic net regression for further analysis. Then binomial logistic regression, generalized additive model, environment risk score (ERS), and weighted quantile sum (WQS) regression were adopted to assess the effects of six metals individual and cumulative exposure on depression risk. Finally, we also examined whether physical activity could mitigate the effects of heavy metal co-exposure on depression risk.

RESULTS

Totally, 4212 participants were included and 7.40% of subjects were with depression. We found urinary tin and antimony were separately associated with increased odds of depression (Sb: OR = 1.285, 95% CI: 1.064-1.553; Sn: OR = 1.281, 95% CI: 1.097-1.495), and a linear dose-response relationship between tin and depression was also noticed (P < 0.05). Meanwhile, urinary heavy metals co-exposure was positively related to depression risk (ERS_Q4: OR = 2.691, 95% CI: 1.399-5.174; WQS_positive: OR = 1.465, 95% CI: 1.063-2.021), in which tin, antimony, and cadmium were identified with greater contributions to the overall mixture effect. In both ERS and WQS models, the significant positive association between the metal mixture and depression risk remained only in those who were inactive in physical activity.

CONCLUSION

Our study concluded the detrimental effect of heavy metals in combined exposure on the risk of depression, which might be attenuated by physical activity.

Association between pyrethroid exposure and risk of depressive symptoms in the general US adults

This study aimed to investigate the association between pyrethroid exposure and the risk of depressive symptoms in adults in the USA. Data of participants aged ≥20 years (n = 6455) from the National Health and Nutrition Examination Survey (NHANES, 2007-2014) were included. 3-Phenoxybenzoic acid (3-PBA), an adequately detected pyrethroid metabolite, was used as a biomarker to assess pyrethroid exposure. Depressive symptoms were defined as the Patient's Health Questionnaire (PHQ-9) total score ≥10 or use of antidepressant. Multivariable logistic regression analyses were performed to examine the association between urinary 3-PBA levels and the risk of depressive symptoms. In this study, 1150 participants (weighted frequency, 18.45%) developed depressive symptoms. Participants in the highest tertile have a higher risk of depressive symptoms than those in the lowest tertile of urinary 3-PBA and weighted OR of 1.28 (95% CI, 1.00-1.63, P=0.019). There was a nonlinear association between urinary 3-PBA and depressive symptoms (P for nonlinearity = 0.034). Mediation analysis showed the mediating effect of trouble sleeping on the association of urinary 3-PBA with depressive symptoms was 28.8% (P = 0.006). Our findings indicate that pyrethroid exposure is associated with the increased risk of depressive symptoms, and trouble sleeping may mediated this association. Further studies should be conducted to validate our findings and elucidate their underlying mechanisms.